JP4166796B2 - Electromagnetic fuel injection device - Google Patents

Description

  The present invention relates to an electromagnetic fuel injection device.

In order to widen the range of combustion control in an internal combustion engine, an improvement in the flow rate controllability of the fuel injection valve is required, and a small flow rate range expansion of the controllable flow rate is required. The flow rate of the fuel can be controlled by the length of the pulse signal (valve opening time signal) sent to the fuel injection valve. However, when the length of the pulse signal becomes shorter, the valve movement becomes unstable and the flow rate becomes unstable. Therefore, an improvement in valve responsiveness is required so that a small flow rate can be injected with the same pulse length.
In the fuel injection valve that opens and closes using the electromagnetic force of the magnetic circuit and injects fuel into the internal combustion engine, the valve closing operation is performed by cutting off the excitation of the coil, but when the excitation of the coil is cut off, For the magnetic member forming the magnetic circuit, an eddy current is generated in a plane perpendicular to the flow of the magnetic flux, so that a residual magnetic flux is generated in the magnetic circuit. For this reason, even after the excitation of the coil is cut off, a problem arises that the attractive force is generated by the residual magnetic flux and the valve closing operation is delayed. Due to this valve closing delay, the minimum flow rate characteristic of the fuel injection valve is deteriorated.
Conventionally, as a measure for improving the responsiveness of the valve, it has been proposed to increase the electric resistance by suppressing the generation of eddy current by forming a groove on the inflow surface of the magnetic flux.
For example, in Patent Document 1 (see Utility Model Registration No. 2599460), a groove is formed along the central axis direction on at least one of the outer surface and the inner surface of the fixed core through which the coil is inserted, The valve responsiveness is improved by reducing eddy currents generated in the fixed iron core and the outer iron core when power feeding is interrupted.
Further, in Patent Document 2 (see Japanese Patent Application Laid-Open No. 2000-18124), a plurality of grooves are formed on the outer periphery of the armature, and ferrite is embedded in the grooves so that the reduction in the attractive force is suppressed and the eddy current is suppressed. Countermeasures for valve delay are taken to improve valve response.

Utility Model Registration No. 2599460 JP 2000-18124 A

The conventional electromagnetic fuel injection device has the following problems.
That is, in Patent Document 1, since the magnetic member that forms the groove is in the fuel passage and is located at the location facing the fuel passage, the flow of the fuel is disturbed when the fuel passes through the inside of the groove. It becomes unstable and deteriorates the flow rate characteristic of the fuel injection valve. In addition, when the groove edge falls off due to the flow of fuel, there is a problem that it becomes a foreign matter and bites into the valve. Further, since the groove is formed on the attraction surface, the groove portion has a minimum magnetic path area than the attraction surface, resulting in a lack of attraction force. Therefore, there is a problem that it is necessary to increase the diameter to secure the attraction area. is there.
Further, in Patent Document 2, although a plurality of grooves are formed on the outer periphery of the armature and ferrite is embedded in the grooves, a decrease in suction force is suppressed. However, since the armature is a movable iron core, it operates in addition to burrs during processing. There is always a shock, and there is a risk of the ferrite missing due to the shock, and there is a risk of falling off. If this falls, the fuel injection valve is broken because it is in the fuel passage. Even if it does not fall off, there is a risk of chipping or the like and biting into the valve. In the worst case, the fuel injection valve may be damaged.
The present invention has been made to solve the above-described problems. In a fuel injection valve having a fuel passage inside, the fuel injection valve does not face the fuel passage and the suction force is reduced. It is an object of the present invention to provide an electromagnetic fuel injection valve in which an eddy current is reduced without interruption and a valve closing operation is quickly started when the excitation of a coil is interrupted.

An electromagnetic fuel injection device according to the present invention includes a housing that forms a yoke portion, a core that forms a fixed core portion, an armature that is disposed opposite to the core via an air gap and forms a movable core portion, and is coupled to the housing. A magnetic circuit of a solenoid coil wound around the outer periphery of the core is constituted by a holder that forms a yoke portion, and the core and the holder are coupled by a ring formed of a nonmagnetic member. The core, the holder, and the valve body supported by the holder constitute a fuel passage, and the valve body that is integrally formed with the armature and is built in the valve body is connected to the solenoid coil in the valve body. In an electromagnetic fuel injection device that reciprocates by electromagnetic force to open and close the fuel injection port,
An annular step portion for fitting the ring is provided on the outer peripheral edge of the core facing the inner peripheral edge of the annular end surface of the holder, and the outer peripheral surface of the core is shallower than the step of the annular step portion of the core. The generation of eddy current is suppressed by providing a plurality of grooves.

In the electromagnetic fuel injection device described in Patent Document 1, since the magnetic member forming the groove is in the fuel passage and is located at the location facing the fuel passage, the fuel flow is disturbed and the flow becomes unstable. When the flow rate characteristics of the fuel injection valve are deteriorated and the groove edge falls off due to the flow of fuel, there is a problem that it becomes a foreign matter and bites into the valve. According to the present invention, all these problems are solved. it can.
Furthermore, since no groove is formed on the suction surface, there is an effect that a suction force does not become insufficient and an increase in diameter for securing a suction area is not necessary.
Further, in Patent Document 2, although a plurality of grooves are formed on the outer periphery of the armature and ferrite is embedded in the grooves, a decrease in suction force is suppressed. However, since the armature is a movable iron core, it operates in addition to burrs during processing. There is a risk that the impact is always applied, and there is a risk that the ferrite will fall out due to the impact, and in this case, the fuel injection valve may be damaged in the worst case because it is in the fuel passage. According to this, all these problems can be solved.
Thus, according to the electromagnetic fuel injection system of the present invention, because it forms a groove in a position not facing the fuel passage, without disturbance of the fuel by the grooves occur, worsening the flow properties and the spray shape Since the foreign matter does not fall out as described above in the fuel passage, the reliability is not impaired.
Further, the groove can be provided without reducing the minimum magnetic passage area, and the flow rate characteristics can be improved by reducing the valve closing delay by suppressing the generation of eddy currents (expansion of the minimum flow range and expansion of the dynamic range).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the drawings, the same reference numerals indicate the same or corresponding parts.
Embodiment 1 FIG.
FIG. 1 shows an electromagnetic fuel injection apparatus according to Embodiment 1 of the present invention, which is implemented in the configuration of the conventional apparatus shown in FIG. 1A is a side sectional view showing the entire electromagnetic fuel injection device, FIG. 1B is an enlarged sectional view of a portion H in FIG. 1, and FIG. 1C is a sectional view of FIG. It is sectional drawing of the core part which looked at the AA line in the arrow direction.
First, the configuration and operation of the conventional apparatus will be described with reference to FIG.
In FIG. 8, the fuel injection valve 1 is composed of a solenoid device 2 and a valve device 9.
The solenoid device 2 includes a housing 3 that is also a yoke portion of a magnetic circuit, a core 5 that is a fixed core portion of the magnetic circuit, and an armature 8 that is disposed to face the core via an air gap S to form a movable core portion. A holder 4 which is coupled to the housing 3 to form a yoke portion and supports a valve body 13 of a valve device 9 which will be described later, a coil housing 6a housed in the housing 3, a coil housing 6a and a core 5 A solenoid coil 6 wound around the outer peripheral side to excite a magnetic circuit, a terminal 7, a cross-sectional L-shaped ring 17 formed of a nonmagnetic member, and a compression that biases the armature 8 toward the valve device 9. A spring 15 and a rod 16 for adjusting the spring force of the compression spring 15 are provided.
Therefore, the magnetic circuit of the solenoid device 2 includes a housing 3, a holder 4, a core 5, a solenoid coil 6, a terminal 7, and an armature 8 that is a movable iron core.
The core 5 and the holder 4 have annular stepped portions 4a and 5a for positioning concentrically on the outer peripheral edge of the annular end surface of the core 5 and the inner peripheral edge of the annular end surface of the holder 4, respectively. Positioning is performed by fitting the horizontal portion and the vertical portion of the L-shaped ring 17 to the portions 4a and 5a, respectively, and the core 5 and the holder 4 are coupled together while fuel sealing is performed at the weld portions 17a and 17b. .
Thus, the magnetic leakage from the core 5 to the holder 4 is prevented by interposing the L-shaped cross-section 17 of the nonmagnetic member between the core 5 and the holder 4. A fuel passage is formed by the core 5, the holder 4, the inner surface of the L-shaped cross-section ring 17 and the valve body 13 described later.

The valve device 9 is integrally formed by welding with the valve body 13 fixed to the inner diameter portion of the holder 4 by press-fitting and welding, and is inserted into the valve body 13 and penetrates the central cylindrical portion (needle). ) 10, a stopper 14 that is sandwiched between the holder 4 and the valve body 13 and restricts the distance of the air gap S formed between the armature 8 and the core 5 (the lift amount of the valve body 10 is restricted), and the valve body 10 is provided with a bearing 11 penetrating through 10 and provided at the tip of the valve main body 13, a bubble sheet 12 which opens and closes the fuel flow path while being in contact with the tip of the valve body 10.
The valve body 10 is pressed against the valve seat 12 by the compression spring 15 together with the armature 8, and is guided to the inner diameter portion 13 a of the valve body 13 by the sliding portion 10 b of the valve body toward the core 5 by the electromagnetic force of the solenoid coil 6. The fuel injection port 21 is opened and closed by being attached to the valve body 13 so as to be reciprocally movable (slidable). In addition, 18 is a spacer, 19 is a rubber ring, and 20 is a filtration net.

Next, the operation will be described.
A solenoid coil 6 of the fuel injection valve 1 is excited by a valve opening operation signal of a control controller (not shown), and a magnetic flux is generated in the magnetic circuit of the solenoid device 2. At that time, a suction force is generated between the opposing surfaces of the core 5 and the armature 8, and the core 5 sucks the armature 8 when the suction force becomes equal to or greater than the spring force of the compression spring 15.
The suction operation is performed until the valve body 10 comes into contact with the stopper 14. At that time, the valve body 10 and the valve seat 12 are opened, and fuel is injected.
Next, the magnetic flux generated in the magnetic circuit of the solenoid device 2 disappears by the valve closing operation signal of the controller. At the same time, the suction force generated in the armature 8 disappears and the spring force of the compression spring 15 closes the valve body 10 and the valve seat 12 (fuel injection stops). The amount of movement of the valve body 10 is regulated by the stopper 14 when the valve is opened and by the valve seat 12 when the valve is closed.

Next, Embodiment 1 of the present invention will be described with reference to FIGS. Note that a description of the same or corresponding parts as those of the conventional apparatus in FIG. 8 is omitted.
In the first embodiment of the present invention, in order to suppress the generation of eddy currents on the outer peripheral surface of the core 105 corresponding to the core 5 of FIG. 8 (the opposite surface on the opposite side of the fuel passage), that is, the peripheral surface facing the solenoid coil 6. The plurality of grooves 105a are provided in parallel.
The groove 105 a has a groove depth L set shallower than the core step T of the annular step portion 5 a of the core 105 as will be described later.
The groove 105a is provided to suppress eddy currents as in the conventional devices described in Patent Document 1 and Patent Document 2, but in order to secure the minimum magnetic path area, the depth L of the groove is Are set as described below.
That is, as shown in FIG. 1B, when the depth L of the groove and the core step of the annular step portion 5a on the core side are T,
T> L
By setting so that the fuel passage is the same structure as the conventional device, it is possible to suppress the eddy current in a state in which the spray characteristics and the reliability are ensured, and as a result, the flow characteristic (particularly, the valve closing delay is suppressed). (Expansion of the minimum flow rate range) can be improved.

Next, the influence of the response delay generated when the groove is formed in the amateur and the effect of the first embodiment will be described with reference to FIGS.
2A is a partial cross-sectional view of the core 105 of FIG. 1, FIG. 2B is a partial cross-sectional view of a conventional apparatus core for comparison with the core 105 of FIG. 1, and FIG. It is a graph which shows the relationship of time-eddy current path (ratio).
In FIG. 2, when the outer diameter D of the core 105 and the number of grooves are N, the eddy current path length of the conventional device core 5 and the eddy current path length of the core 105 of the first embodiment are

Eddy current path length of conventional device = πD
Eddy current path length in the first embodiment = πD + 2L * N

Therefore, from the graph of FIG. 3, when the path length of the conventional example is 1, this length is equal to or greater than 1.5 (eddy current path ratio is equal to or greater than 1.5), which is equivalent to the case where grooves are formed in the amateur. It can be seen that a level of eddy current suppression effect can be obtained. From this,

If the eddy current path length of the conventional device * 1.5 <the eddy current path length of the first embodiment,
πD * 1.5 <(πD + 2L * N)
L> π * D / 4 * N
The relationship is obtained.

That is, according to this result, if the length of the eddy current path is L> π * D / 4 * N with respect to the conventional device, the effect of suppressing the eddy current is almost the same level as when the groove is formed in the amateur. As well as the problem of fuel flow disturbance and reliability.
In addition, from the above, even if the core step T is small and the groove depth L is shallow, the effect of suppressing eddy current can be obtained by increasing the number N of grooves.
FIG. 4 is a graph showing the opening / closing transient change of the valve body, showing which part of the lift is improved by reducing the eddy current, and showing the improvement of the valve closing delay due to the residual magnetism.

Next, in the first embodiment, the upper end portion 105p of the axial groove 105a provided on the outer peripheral surface of the core 105 is extended longer than the upper end portion 6p of the solenoid coil 6 by P.
As a result, when the magnetic flux from the solenoid coil 6 flows into the core side surface, the magnetic flux surely passes through the groove 105a, so that a more effective eddy current suppressing effect can be obtained.

Embodiment 2. FIG.
FIG. 5 shows an electromagnetic fuel injection apparatus according to Embodiment 2 of the present invention, which is implemented in the configuration of the conventional apparatus shown in FIG. 5A is a side sectional view showing the entire electromagnetic fuel injection device, FIG. 5B is an enlarged sectional view of the L portion in FIG. 5, and FIG. 5C is a cross-sectional view taken along line BB in FIG. It is the top view of the holder 106 which looked at the line | wire in the arrow direction. Note that a description of the same or corresponding parts as those of the conventional apparatus in FIG. 8 is omitted.
In the second embodiment of the present invention, a plurality of grooves 104a are provided radially on the annular end surface of the holder 104 corresponding to 4 in FIG. 1 with respect to the center of the holder.
In the groove 104a, the depth G of the groove is set to be shallower than the width F of the holder step of the annular step portion 4a.
In this manner, by the setting of the F> G, the groove does not decrease magnetic path area since it is not possible according to the magnetic path portion, can be prevented a reduction in the minimum magnetic path area, also face the fuel passage Therefore, the eddy current can be suppressed without disturbing the fuel flow.

Next, in the second embodiment, the outer end 104q of the groove 104a is extended longer than the end 6q of the solenoid coil 6 by Q.
As a result, when the magnetic flux from the solenoid coil 6 flows into the end face of the holder, the magnetic flux surely passes through the groove 104a, so that a more effective eddy current suppressing effect can be obtained.

Embodiment 3 FIG.
FIG. 6 shows an electromagnetic fuel injection apparatus according to Embodiment 3 of the present invention, which is implemented in the configuration of the conventional apparatus shown in FIG. FIG. 6A is a side sectional view showing the entire electromagnetic fuel injection device, and FIG. 6B is an enlarged sectional view of a portion K in FIG. Note that a description of the same or corresponding parts as those of the conventional apparatus in FIG. 8 is omitted.
The electromagnetic fuel injection device according to the third embodiment shown in FIG. 6 includes a plurality of grooves 205a on both the core 205 and the holder 204, that is, the outer peripheral surface of the core 205 facing the solenoid coil 6 and the annular end surface of the holder 204. By providing each 204a, generation of eddy current is suppressed.
That is, in FIG. 6, an annular stepped portion 5 a for fitting the ring 17 is provided on the outer peripheral edge of the core 205 facing the inner peripheral edge of the annular end surface of the holder 204, and the annular stepped portion of the core is provided on the outer peripheral surface of the core 205. A plurality of grooves 205a shallower than the step 5a are provided.
Further, an annular stepped portion 4a for fitting the ring 17 is provided on the inner peripheral edge of the annular end surface of the holder 204 facing the outer peripheral edge of the annular end surface of the core 205, and the annular shape of the holder is formed on the annular end surface of the holder 204 facing the solenoid coil 6. A plurality of grooves 204 a shallower than the step of the stepped portion 4 a are provided radially with respect to the center of the holder 204.
As described above, when the groove depth cannot be sufficiently secured in each of the core and the holder, grooves may be formed in both of them.

Embodiment 4 FIG.
7 (a) and 7 (b) show a fourth embodiment of the present invention, and are a sectional view corresponding to the sectional view of the core portion of FIG. 1 (c) and an enlarged view thereof.
In FIG. 7, a groove 305a provided in the core 305 corresponds to the groove 105a (FIG. 1) or the groove 104a (FIG. 5), and has a trapezoidal shape in order to improve the workability of the groove shape. Even in this case, the effect of reducing the eddy current can be obtained similarly.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the whole structure of the electromagnetic fuel injection apparatus which is Embodiment 1 of this invention, (a) is a sectional side view which shows the whole electromagnetic fuel injection apparatus, (b) is H in FIG. (C) is sectional drawing of the core part which looked at the AA line of FIG. 1 in the arrow direction. (A) is a partial cross-sectional view of the core 105 shown in FIG. 1, and (b) is a partial cross-sectional view of a conventional apparatus core for comparison with the core 105 shown in FIG. It is a graph which shows the relationship of valve closing time-eddy current path (ratio). It is a graph which shows the opening-and-closing transient change of a valve body. Embodiment 2 An electromagnetic fuel injection device according to Embodiment 2 of the present invention is shown, (a) is a side sectional view showing the whole electromagnetic fuel injection device, (b) is an enlarged sectional view of an L portion, and (c) is It is the top view of the holder 106 which looked at the BB line in the arrow direction. FIG. 3 shows an electromagnetic fuel injection device according to Embodiment 3 of the present invention, in which (a) is a side sectional view showing the whole electromagnetic fuel injection device, and (b) is an enlarged sectional view of a K portion. Embodiment 4 of this invention is shown, (a) is sectional drawing equivalent to sectional drawing of the core part of FIG.1 (c), (b) is the enlarged view. It is a sectional side view which shows the whole structure of the conventional electromagnetic fuel injection apparatus.

Explanation of symbols

1 Fuel Injection Valve 2 Solenoid Device
3 Housing 4 Holder 4a Annular Step 5a Annular Step 105 Core 105a Groove
6 Solenoid coil 6a Coil housing
7 Terminal 8 Amateur
9 Valve device 10 Valve body (needle)
10b Sliding part of valve body 11 Bearing 12 Bubble sheet 13 Valve body 13a Inner diameter part 14 Stopper 15 Compression spring 16 Rod 17 Cross-section L-shaped ring 17a Welding part 17b Welding part

Claims (3)

The housing that forms the yoke portion, the core that forms the fixed core portion, the armature that faces the core through the air gap and forms the movable core portion, and the holder that is combined with the housing to form the yoke portion. The magnetic circuit of the solenoid coil wound around the outer periphery of the core is configured, and the core and the holder are supported by the holder by connecting the core and the holder with a ring formed of a nonmagnetic member. A fuel passage is formed by the valve body, and a valve body that is integrated with the armature and is built in the valve body is reciprocated by the electromagnetic force of the solenoid coil in the valve body to open and close the fuel injection port. In the electromagnetic fuel injection device
An annular step portion for fitting the ring is provided on the outer peripheral edge of the core facing the inner peripheral edge of the annular end surface of the holder, and the outer peripheral surface of the core is shallower than the step of the annular step portion of the core. An electromagnetic fuel injection device characterized in that generation of eddy current is suppressed by providing a plurality of grooves. The housing that forms the yoke portion, the core that forms the fixed core portion, the armature that faces the core through the air gap and forms the movable core portion, and the holder that is combined with the housing to form the yoke portion. The magnetic circuit of the solenoid coil wound around the outer periphery of the core is configured, and the core and the holder are supported by the holder by connecting the core and the holder with a ring formed of a nonmagnetic member. A fuel passage is formed by the valve body, and a valve body that is integrated with the armature and is built in the valve body is reciprocated by the electromagnetic force of the solenoid coil in the valve body to open and close the fuel injection port. In the electromagnetic fuel injection device
An annular stepped portion for fitting the ring is provided on the inner peripheral edge of the holder facing the outer peripheral edge of the annular end surface of the core, and the annular stepped portion of the holder is provided on the annular end surface of the holder facing the solenoid coil. multiple providing it radially with respect to the center of the holder and from the shallow grooves stepped parts, magnet type fuel injection device electrostatic you characterized by inhibiting the generation of eddy currents. When the number of grooves provided on the outer peripheral surface of the core is N and the outer diameter of the core is D, the depth L of the groove is set as L> π * D / 4 * N electromagnetic fuel injection device according to claim 1 Symbol mounting features.

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