JP2000145593A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a durable high-quality fuel injection nozzle that includes a detector capable of generating concrete detection signals on nozzle needle lift motion without magnetizing a pressure pin. SOLUTION: A detector 21 for detecting valve opening timing from the lift motion of a nozzle needle 7 is positioned or installed immovably in the middle section of a spring receiving hole 2 in a nozzle holder 1. The detector 21 consists of a magnet 23 and a detecting coil wound about the magnet 23. Across both magnetic poles of the magnet 23, a pressure pin 11 of a magnetic substance interlocked with the needle 7 is passed in gap-forming relation to them. The magnitude of such magnetic resistance in the magnetic circuit or between the pin 11 and the magnet 23 as by the gap is changed as the pin 11 moves, to thus cause the detecting coil to induce electromagnetic voltage, which is in turn utilized as detection signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection nozzle provided in an internal combustion engine, for example, a diesel engine.
In particular, the present invention relates to a fuel injection nozzle in which a detection device for detecting, for example, a valve opening timing, a valve closing timing, and the like for the injection control is incorporated in a nozzle holder.

[0002]

2. Description of the Related Art In recent years, a detection device for detecting an injection start (opening) timing and an injection ending (closing) timing for the purpose of more precise injection control has been developed in order to respond to stricter exhaust gas regulations of diesel engines. Requested.

As an example satisfying such a demand, a fuel injection nozzle described in Japanese Patent Publication No. 3-9307 is known. In this publication, a detection device is incorporated in a deep portion of a spring accommodating hole of a nozzle holder accommodating a spring that presses down a pressure pin that comes into contact with a nozzle needle. This detection device includes a core (magnetic core) inserted into a center hole of the induction coil, and a pressure pin inserted into the center hole and capable of coming into contact with and separating from the tip of the core, and the core biases the pressure pin. It is urged in the direction of the pressure pin by a core urging spring different from the spring, and is provided so that when the nozzle needle lifts, it is pushed by the pressure pin to escape.

In this case, there is an air gap between the core and the pressure pin when the valve is closed, and this gap disappears when the tip of the nozzle needle contacts the core when the nozzle needle is lifted. Therefore, a change in voltage electromagnetically induced in the induction coil based on a change in magnetic flux due to such a change in the air gap can detect the on-off valve but cannot detect the lift amount of the nozzle needle (gap 0).
Thereafter, since the signal does not change, the lift amount cannot be detected.)

Another conventional example is disclosed in Japanese Patent Application Laid-Open No. 6-3073.
A fuel injection nozzle described in Japanese Patent Publication No. 13 is also known. In this device, a detecting device is arranged at a middle portion, not a depth portion of a spring accommodating hole accommodating a spring for biasing a nozzle needle, in particular, near a spring receiving portion of a pressure pin for receiving the spring and on a nozzle needle side. ing. This detector is
Since the coil close to the spring receiver is adapted to obtain a signal corresponding to a change in the gap between the coil and the spring receiver, it is possible to detect the lift of the nozzle needle as a change in the gap. it can.

[0006]

However, in the fuel injection nozzle disclosed in Japanese Patent Publication No. 3-9307, in which the detecting device is disposed at the back of the spring receiving hole, the movement of the nozzle needle is moved to the back of the spring receiving chamber. To communicate, a long pressure pin associated with this needle is required. Therefore, since the mass of the high-speed moving part including the nozzle needle and the pressure pin increases, there is a possibility that the responsiveness of the fuel injection nozzle that requires a high-speed response is deteriorated. Further, since the pressure pin penetrates the spring for biasing the spring in the axial direction, it becomes an obstacle in making the spring thinner, and the restriction on the spring design increases. In addition, since the detection device is disposed in the inner part of the spring accommodating chamber, the total length of the nozzle holder becomes longer in accordance with the axial dimension of the device, and there is a problem that the assembly to the engine involves modification.

[0007] In the fuel injection nozzle disclosed in Japanese Patent Application Laid-Open No. H6-307313, in which the detecting device is arranged at an intermediate portion of the spring receiving hole,
Although the above-mentioned problem of Japanese Patent Publication No. 3-9307 can be solved, since a detection device having a detection unit composed of a passive element using only a coil is used, the detection device itself detects a valve opening timing and the like. It is impossible to generate a detection signal of a predetermined level or more. Therefore, in this conventional example, since a special converter is required for detection,
There is a problem that the configuration must be complicated.

Replacing the detecting device disclosed in Japanese Patent Application Laid-Open No. Hei 6-307313 with the detecting device disclosed in Japanese Patent Publication No. Hei 3-9307 is indispensable because the latter detecting device requires a core which is biased toward the pressure pin by a spring. Due to the configuration, the pressure pin may be shortened, but a long core inserted into a spring for biasing the pin is required, and a correspondingly long induction coil is required. Therefore, the induction coil must be large in size to accommodate the spring for urging the pressure pin, so that the diameter of the entire nozzle is increased and the total length is equal to the length of the spring for urging the core. Since it becomes long, it is unsuitable for a fuel injection nozzle having a limited physical size, and such a large-sized one is considered to be impractical.

In each of the publications described above, since no magnet is used for the detection device, the strength of the detection signal taken out by the detection coil is small, and the reliability of detection is low. There is a problem of low.

Therefore, paying attention to this point, a magnet is provided at the end of the pressure pin opposite to the nozzle needle, and a detection coil for accommodating the magnet is disposed in the spring accommodating hole. A fuel injection nozzle with a detection device that induces a voltage in a detection coil by an electromagnetic induction effect accompanying movement in the coil and takes out the voltage as a detection signal is conceivable. However, it was found that this had the following problems.

When the magnet is a separate part from the pressure pin and is connected to the pressure pin which reciprocates at high speed (high-speed vibration) together with the nozzle needle by joining or assembling, the magnet falls off due to the high-speed vibration of the pressure pin. There is a possibility that it may be dropped or chipped. In order to make a pressure pin without using a separate magnet, it is necessary to magnetize this pin.At this time, if the entire pressure pin is magnetized, the nozzle needle that this pin contacts will be magnetized during use. As a result, there is a possibility that iron powder accumulates on the valve and adversely affects fuel injection. further,
It is difficult to partially magnetize the pressure pin, and the pressure pin, which requires wear resistance, is usually made of high carbon steel. You can't even get a strong magnet. Therefore, in order to obtain a required level of induced electromotive force, it is necessary to increase the number of turns of the detection coil.However, since the size of this coil is limited by the size determined for the entire nozzle, the coil A thin wire must be used for the element wire, which may cause problems such as easy disconnection and an increase in coil resistance.

Accordingly, a first problem to be solved by the present invention is to provide a detection device capable of generating a clear detection signal about the lift of a nozzle needle without magnetizing a pressure pin, and to provide a high durability device having excellent durability. It is to obtain a high quality fuel injection nozzle.

A second object of the present invention is to provide a fuel injection nozzle which can secure a high-speed response and does not increase the size in solving the first object. .

[0014]

SUMMARY OF THE INVENTION The present invention is based on a fuel injection nozzle in which a detection device for detecting a lift of a nozzle needle is incorporated in a nozzle holder. In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that the detection device includes a magnet built in a stationary state in the nozzle holder, and a detection coil wound around the magnet, A pressure pin made of a magnetic material interlocking with the nozzle needle is passed between both magnetic poles of the magnet, and a gap whose size changes in accordance with the movement of the pressure pin is provided in a magnetic circuit extending between the pressure pin and the magnet. It is characterized by the following.

According to the first aspect of the present invention, since the pressure pin passed between the magnetic poles of the magnet included in the detection device is made of a magnetic material, the magnetic circuit formed by the magnetic force of the magnet passes through the pressure pin. The gap provided in the magnetic circuit functions as a magnetic resistance part, and its size changes according to the movement of the pressure pin.

Accordingly, the reluctance is changed along with the size of the gap which changes in accordance with the axial movement of the pressure pin linked to the nozzle needle, and the magnetic flux passing through the detection coil wound on the magnet changes accordingly. A voltage proportional to the change is generated in the detection coil by electromagnetic induction. In this manner, the detection device detects the lift of the nozzle needle as a change in the magnetic resistance in the magnetic circuit using the pressure pin as a part of the magnetic path by the detection coil.

In this case, a magnet is used as described above in comparison with the case where the detection is performed only by the coil, and the detection coil wound therearound generates a voltage corresponding to the magnetic flux passing therethrough. Therefore, the detection device can generate a clear detection signal of a predetermined level or more, and does not require a special converter for detection.

Since the detection device having a magnet, which is a separate component from the pressure pin, is built in the nozzle holder in a stationary state instead of the pressure pin, the force accompanying the high-speed movement of the pressure pin acts on the magnet. Gone
There is no danger of magnets falling off or missing. In addition, the use of the above-described detection device eliminates the need to provide a magnet integrally with the pressure pin, and can solve various problems associated with magnetizing the pressure pin.

In carrying out the first aspect of the present invention, the gap may be provided in the radial direction of the pressure pin as in the second aspect of the invention.
In this case, the magnet is U-shaped and the detection coil is wound between both magnetic poles of the magnet to form the detection device, as in the invention of claim 3 which is dependent on the invention of claim 2. It is preferable that a step is provided in the pressure pin passed between the magnetic poles of the detecting device, and the size of the gap is changed by the step.

Similarly, in carrying out the invention of claim 1, the gap can be provided in the thrust direction of the pressure pin as in the invention of claim 4 which depends on the invention. Claim 5 dependent on the invention
The magnet has a pair of magnetic poles protruding in the thrust direction of the pressure pin, and a magnetic pole facing portion facing the tips of both magnetic poles is provided on the pressure pin, and the two magnetic poles and the magnetic pole facing portion are provided. And a gap in the thrust direction of the pressure pin.

Further, in carrying out the invention of claim 5, it is preferable that the magnetic pole opposing portion is formed by the spring receiving portion as in the invention of claim 6 dependent thereon. According to the present invention, since it is not necessary to form a magnetic pole facing portion in addition to the spring receiving portion, the inertial mass of the pressure pin, which is a part of the high-speed moving portion, can be prevented from increasing.

In order to solve the second problem, the invention according to claim 7 is dependent on any one of claims 1 to 6, wherein the detecting device includes the nozzle needle attached to the nozzle needle. The pressure pin is disposed closer to the nozzle needle than a spring receiving portion of the pressure pin that receives a spring that presses the pressure pin.

According to the seventh aspect of the present invention, since the detecting device is located not at the end of the pressure pin but at the intermediate portion in the axial direction and performs the detecting operation at the position at the position, the pressure is increased. It is not necessary to extend the end of the pin opposite to the nozzle needle to the inside of the spring accommodating hole accommodating the spring. For this reason, the detection device does not cause the nozzle holder to increase the overall length, and the shortening of the pressure pin can reduce the inertial mass of the moving portion that moves at high speed, and furthermore, the pressure pin has a spring for biasing it. It is less likely to be an obstacle when making it thinner.

Further, in order to solve the first problem, a structure in which a detecting device is incorporated at a position distant from the pressure pin,
The invention according to claim 8 is characterized in that the detection device includes a magnet which is statically incorporated in the nozzle holder at an end side of the spring chamber opposite to the side where the pressure pin end is arranged, a core which is combined with the magnet,
A detection coil wound around the core, and the core is
A projection protrudes into the interior of the spring chamber until the nozzle needle end is closely opposed via a predetermined gap.The projection forms a magnetic circuit across the magnet, the core, the pressure pin and the nozzle holder, and A detection signal is output from the coil according to a change in the gap due to the movement, and a clear detection signal is generated for the lift of the nozzle needle without magnetizing the pressure pin, as described in the preceding claims. In addition, a high-quality fuel injection nozzle with high-speed response and excellent durability has been realized. In addition, since the magnet has a magnetic pole disposed at a position away from the combustion chamber of the engine, the magnet is less likely to be demagnetized due to a high temperature.

According to a ninth aspect of the present invention, the detection coil is moved with respect to the core portion arranged on the end side of the spring chamber so as to avoid not only the influence of the magnet due to the high temperature but also the influence of the detection coil. The detection coil was configured to be wound in the circumferential direction, and a magnet was mounted immediately above the detection coil so that both the detection coil and the magnet were incorporated at the point of the nozzle holder farthest from the combustion chamber of the engine.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a longitudinal sectional view showing the entire structure of the fuel injection nozzle A according to the first embodiment. The nozzle holder indicated by reference numeral 1 in the figure has first and second nozzle holders located on the same axis. It has two ends 1a and 1b and a third end 1c branched from the axis. A spring accommodation hole 2 having a first step 2a and a second step 2b is formed in the nozzle holder 1 so as to penetrate in the axial direction.
The signal extraction hole 3 connected to the nozzle b extends through the inside and outside of the nozzle holder 1. One end of the spring housing hole 2 opened to the second end 1b is used as a return port 2c for surplus fuel, and communicates with the fuel tank via a return pipe (not shown).

A holder cap 4 is provided on the outer periphery of the first end 1a.
The cap 4 accommodates a part of a nozzle body 5 made of a high-hardness metal material and a metal packing 6 respectively. The packing 6 is sandwiched between the first end 1a and the nozzle body 5 by screwing the holder cap 4 into the first end 1a.

The small-diameter portion of the stepped cylindrical nozzle body 5 penetrates the holder cap 4 and protrudes to the outside, and the tip portion forms a nozzle portion 5a. A nozzle needle 7 is accommodated in a needle sliding hole 5b provided at the center of the nozzle body 5 with high accuracy so that the nozzle needle 7 can slide only in the axial direction. The needle 7 serves as a valve element of the fuel injection nozzle A, and its tip (not shown) is brought into contact with and separated from the valve seat surface of the nozzle portion 5a, thereby injecting fuel as the valve is opened and closing. The stop of the fuel injection is performed with the valve.

As shown in FIG. 3, the small-diameter portion 7a forming the other end of the nozzle needle 7 penetrates the packing 6 into a stepped hole 6a communicating with the first end 1a side of the spring receiving hole 2. Has been inserted. A ring-shaped relay member 9 shorter than the height of the hole is accommodated in the large-diameter hole of the stepped hole 6a on the nozzle body 5 side so as to be movable in the axial direction. The small-diameter tube portion of the tubular spring receiver 10 is inserted into the small-diameter hole portion of the nozzle holder 1 through the hole portion. The distal end of the small-diameter tubular portion of the tubular spring receiver 10 is opposed to the relay member 9 with a slight gap so that the nozzle spring 7 is pressed and moved via the relay member 9 when the nozzle needle 7 is lifted. The small diameter portion 7a penetrates the relay member 9 and is inserted into the cylindrical spring receiver 10. The clearance between the small-diameter portion 7a and the relay member 9 and the small-diameter cylindrical portion, and the clearance between a pressure pin described later and the small-diameter cylindrical portion are used as a return path for the surplus fuel.

A fuel passage 8 is formed in the nozzle holder 1, the packing 6, and the nozzle body 5 so as to sequentially pass therethrough. The third end 1c serving as an inlet of the fuel passage 8 has a structure shown in FIG.
A fuel injection pump P for supplying high-pressure fuel as shown in FIG.
Are connected via a fuel injection pipe S. In FIG. 1, C denotes a controller C such as an ECU (electronic control unit) to which a detection signal of a later-described detection device 21 provided in the fuel injection nozzle A is supplied. The controller C controls the operation of the fuel injection pump P. It has become so.

A pressure pin 11 is accommodated in the spring accommodating hole 2 so as to be movable in the axial direction. The tip of the pin 11 passes through the center of the stepped hole 6a and the nozzle needle 7
Is in contact with the end face of the small diameter portion 7a. The pressure pin 11 and the nozzle needle 7 are provided continuously on the same axis. The nozzle needle 7 sliding on the nozzle body 5 and the pressure pin 11 reciprocating at high speed together with the needle 7 are all made of high carbon steel.

The pressure pin 11 is connected to the nozzle needle 7
A spring receiving portion 11a is integrally provided at an end opposite to the above, and a large-diameter portion 11b is integrally provided near the spring receiving portion 11a. Therefore, as shown in FIG. 4 and FIG. 5, the neck-shaped shaft portion 1 extending from the spring receiving portion 11a to the large-diameter portion 11b.
1c and the large diameter portion 11b are connected via an annular step 11d. Further, as shown in FIG. 4, the spring receiving portion 11a has, for example, a circular flange shape continuous over the entire circumferential direction.

As shown in FIG. 3, a first spring chamber 2d formed in a space above the spring receiving hole 2 with the second step 2b as a boundary.
Accommodates a first spring 12 that constantly urges the pressure pin 11 toward the nozzle needle 7. In a second spring chamber 2e formed in a space below the spring housing hole 2 with the second step 2b as a boundary, a second spring 13 that constantly urges the cylindrical spring receiver 10 toward the relay member 9 is provided. Is housed. The first spring 12 made of a coil spring is assembled in a compressed state while being supported at one end by a spring receiving portion 11a of the pressure pin 11 and supported by a spring receiving ring 14 fixed to the first step 2a. The end of the pressure pin 11 slightly projecting from the spring receiving portion 11a is only slightly inserted into the inside of the first spring 12, and the pressure pin 11 is provided without penetrating the first spring 12 in the axial direction. I have. The second spring 13 made of a coil spring has one end supported by the cylindrical spring receiver 10 on the nozzle needle 7 side and the other end supported by a detection device 21 described below fixed to the second step 2b, and compressed. Built into the state. In this embodiment, the spring force of the first spring 12 is smaller than the spring force of the second spring 13, but the spring force of the first spring 12 and the second spring 13 may be larger in the second spring 13. The pressure pin 11 passes through the second spring 13.

A detection device 21 for detecting the lift of the nozzle needle 7 for detecting the valve opening timing and the valve closing timing of the nozzle A is incorporated in the nozzle holder 1. As shown in FIGS. 4 and 5, the detection device 21 includes a magnet 23, a detection coil 24, and a case 22 made of an electric insulator.

More specifically, the magnet 23 made of a hard magnetic material is shown in FIG.
As shown in FIG. 5A, the magnetic poles 23a and 23b formed at both ends thereof have different polarities (N-pole and S-pole). The distance between the magnetic poles 23a and 23b is slightly larger than the diameter of the large diameter portion 11b of the pressure pin 11. Furthermore,
An arc-shaped relief groove 23c is formed on the inner surface of the magnet 24 between the magnetic poles 23a and 23b. Through this groove 23c, the detection coil 24 is connected to both magnetic poles 23 of the magnet 23.
a and 23b. Escape groove 23
The provision of the pressure pin 11 and the detection coil 24
It is excellent in that it can eliminate interference with the camera. As shown in FIG. 5, the case 22 has a circular shape in plan view, has a concave cross section, and has a pin through hole 22 in the center of the bottom wall.
a in which the detection coil 2
The magnet 23 with 4 is accommodated and fixed. Also, lead wires 25 (see FIG. 3) are connected to both ends of the accommodated detection coil 24, which penetrate the peripheral wall of the case 22 and are drawn out to the outside.

Detection unit 2 unitized as described above
1 is accommodated in the spring accommodating hole 2 with the open end face of the case 22 abutted against a second step 2b in the middle of the spring accommodating hole 2. In this stored state, the second spring 13 is in contact with the outer surface of the bottom wall of the case 22. for that reason,
The detection device 21 is located at a middle portion, not a depth portion, of the spring receiving hole 2 of the nozzle holder 1 as a stationary member, and is positioned in a stationary state by the spring force of the second spring 13.
It is arranged between the second two springs 12, 13. As shown in FIG. 3, the lead wire 25 led out of the detection device 21 is pulled out of the nozzle holder 1 through a plug 26 press-fitted into the signal extraction hole 3 in a blind plug shape, and is drawn out of the nozzle holder 1. It is connected to C.

The pressure pin 11 passes through the detecting device 21 in the spring receiving hole 2. By this penetration, the pressure pin 11 is passed between the magnetic poles 23a and 23b as shown in FIGS. 4 and 5, and these pressure poles 13a and 13b
, An air gap g in the radial direction of the pressure pin 11 is formed. When the nozzle A is in the valve closed state, the pressure pin 11 is set so that the step 11d slightly covers the lower end surface (in the drawing) of the magnet 22 as shown in FIG. The pressure pin 11 is axially moved (lifted) in conjunction with the nozzle needle 7 with this position as a lower limit position. The spring receiving portion 11a of the pressure pin 11 is located near the second step 2b and on the opposite side (upper side in FIG. 3) of the detecting device 21 with the step 2b as a boundary.

The arc-shaped space between the magnetic poles 23a and 23b of the magnet 23 (indicated by a two-dot chain line in FIG. 4) and the clearance between the magnet 23 and the case 22 and the pressure pin 11 correspond to the excess fuel return path. Used as Similarly, the clearance between the spring receiving portion 11a of the pressure pin 11 and the inner peripheral surface of the spring receiving hole 2 is also used as a return path for surplus fuel.

In the two-stage valve-opening fuel injection nozzle A having the above construction, as high-pressure fuel is fed from the fuel injection pump P to the fuel passage 8, the internal pressure of the passage 8 is reduced by the first spring 12.
When a valve opening force greater than the pressing load of the nozzle needle 7 is applied to the nozzle needle 7, the nozzle needle 7 moves toward the second end 1 b with the pressure pin 11 against the urging force of the first spring 12. Move (lift). The upward movement at this time is performed until the nozzle needle 7 pushes up the relay member 9 and the member 9 hits the small-diameter tubular portion of the tubular spring receiver 10 urged by the second spring 13. Thereby, the nozzle needle 7 is pre-lifted. The fuel is injected into the combustion chamber of the diesel engine from an injection hole (not shown) of the nozzle portion 5a by opening the valve due to the rise, and the fuel injection starts combustion corresponding to a so-called pilot flame in the combustion chamber.

Since the pumping of the fuel is continued, the internal pressure of the fuel passage 8 rises, and this is caused by the first and second springs 12,
When the maximum valve opening pressure which is larger than the total load by the first spring 13 is reached, the nozzle needle 7 pushes the cylindrical spring receiver 10 against the urging force of the second spring 13 and further moves the first spring 1.
2. Lift the pressure pin 11 against the urging force of 2,
Thus, the nozzle needle 7 is lifted to the maximum. According to the maximum lift, the fuel in the fuel passage 8 is mainly injected into the combustion chamber where a pilot flame has been formed, so that the fuel can be appropriately burned.

When the fuel pumping from the fuel injection pump P ends, the pressure in the fuel passage 8 decreases. When the pressure reaches the set valve closing pressure, the first and second springs 1
Due to the urging forces 2 and 13, the nozzle needle 7, the pressure pin 11, the cylindrical spring receiver 10, and the relay member 9 are respectively pressed and moved toward the nozzle tip side against the fuel pressure, and return to the original state. Therefore, the tip of the nozzle needle 7 is seated, the injection hole is closed, and the combustion injection ends.

In the fuel injection, the excess high-pressure fuel is removed by the clearance between the needle sliding hole 5b and the nozzle needle 7, the clearance between the small diameter portion 7a of the nozzle needle 7 and the relay member 9, the small diameter portion 7a and the small diameter portion 7a. Through the clearance between the pressure pin 11 and the cylindrical spring receiver 10, it flows into the lower part of the spring housing hole 2 housing the second spring 13,
Further, a spring accommodation hole 2 accommodating the first spring 12 through a clearance between the pressure pin 11 and the detection device 21.
After flowing into the upper portion of the return port 2 through the clearance between the hole 2 and the spring receiving portion 11a of the pressure pin 11,
c, from which it flows out and returns to the fuel tank.

By the way, the magnetic flux flowing from the N pole (magnetic pole 23a) to the S pole (magnetic pole 23b) of the magnet 23 of the detecting device 21 built in the spring receiving hole 2
A magnetic circuit is formed that flows radially through a pressure pin 11 made of a magnetic material that is passed between a and 23b. On the other hand, since the pressure pin 11 is reciprocated at high speed in the axial direction in conjunction with the nozzle needle 7 as described above, the correlation between the pressure pin 11 and the detection device 21 is shown in FIG. Compared to the state when the fuel injection nozzle A is closed (at the time of no lift), when the fuel injection nozzle A is opened (at the time of lift), the state changes to the state shown in FIG. That is, the large diameter portion 11b of the pressure pin 11 is
3 hardly enter the inside of the large diameter portion 11 when the pressure pin 11 is lifted during the lift.
b penetrates so as to mostly fill the inside of the magnet 23. As a result, the air gap g formed between the magnetic poles 23a and 23b of the magnet 23 and the pressure pin 11 passing therebetween is smaller when the valve is opened than when the valve is closed.

This gap g is in the magnetic circuit.
Therefore, the magnetic resistance with respect to the magnetic circuit is smaller when the valve is opened (during a lift) than when the valve is closed (during a non-lift).
Since the magnetic flux passing through the magnet 23, in other words, the magnetic flux passing through the detection coil 24 is changed in accordance with such a change in the magnetic resistance, a voltage proportional to the change in the magnetic flux is generated in the detection coil 24 by the electromagnetic induction. . The voltage thus generated is supplied to the controller C via the lead wire 25 as a lift speed detection signal.

The time chart of FIG. 2 shows the relationship between the change in the lift amount of the nozzle needle 7, the change in the detection signal output from the detection device 21, and the valve opening signal T. As is clear from this, the controller C issues a valve opening signal T when the detection signal first exceeds the valve opening threshold value U set in the valve opening detection section (the time when the pre-lift is performed), and closes the controller C. When the detection signal first exceeds the valve closing threshold value V set in the valve detection section, the valve opening signal T is cut off, and fuel injection is controlled by the valve opening signal T. In FIG. 2, O is a valve opening time and W is a valve closing time.
The first peak waveform Q1 on the + side of the detection signal is a start signal component of the pre-lift, the second peak waveform Q2 on the plus side is a start signal component of the maximum lift, and the negative peak waveform Q3 is a lift signal component corresponding to the end signal of the maximum lift. It is a speed signal.

As described above, the fuel injection nozzle 1 having the above structure
In the above, the size of the gap g in the magnetic circuit formed by the magnet 23 through the pressure pin 11 interlocking with the nozzle needle 7 is changed according to the axial movement of the pressure pin 11 and wound around the magnet 23. The detection coil 24 generates a voltage proportional to a change in magnetic flux passing through the detection coil 24, and the lift of the nozzle needle 7 is used as a change in the magnetic resistance in the magnetic circuit using the pressure pin 11 as a part of the magnetic path. 24.

By using the magnet 23 to generate a voltage corresponding to the change in the magnetic flux in the detection coil 24 wound therearound, the detection is performed at a predetermined level compared to the case where the detection is performed only by the coil. The above clear detection signal can be generated by the detection device 21 alone. Therefore, the reliability of detection can be improved, and a special converter is not required for detection, so that the configuration of the detection system does not become complicated.

Moreover, the detection device 21 is provided not with the pressure pin 11 but with the second step 2 b and the second spring 13 in a stationary state by providing the magnet 23 which is a separate component from the pressure pin 11. Since the pressure pin 11 is held and incorporated in the nozzle holder 4, the force accompanying the high-speed movement of the pressure pin 11 does not act on the magnet 23 of the detection device 21.
Therefore, unlike the case where the magnet 23 is attached to the end of the pressure pin 11, there is no danger that the magnet 23 may fall off or break, and the magnet 23 is excellent in durability and can be maintained in a stationary state. The possibility that the wound detection coil 24 can fall off can be eliminated.

Further, since the magnet 23 is not provided on the pressure pin 11 as described above, it is not necessary to provide a magnetized part integrally with the pin 11. Therefore, there is no need to magnetize the pressure pin 11, so that various problems associated with magnetizing the pressure pin 11 can be solved, and the quality of the entire nozzle A can be improved. That is, as in the case of using a pressure pin magnetized as a whole, the nozzle needle 7
Is magnetized during use, and there is no fear that iron powder accumulates on the valve and adversely affects fuel injection. In addition, it is not necessary to perform a difficult partial magnetization on the pressure pin 11 made of high carbon steel, and a necessary level of induction is required to compensate for the fact that a strong magnet cannot be obtained even if magnetized. Since it is not necessary to increase the number of turns of the detection coil 24 in order to obtain electric power, a thin wire may be used as the coil wire based on the size restriction of the detection coil 24 due to the size determined for the entire nozzle. Therefore, there is no problem that the wire is easily disconnected or the resistance of the coil increases.

Further, the fuel injection nozzle A having the above-described structure is configured such that the detecting device 21 built in the spring receiving hole 2 in a stationary state is connected to the inner end of the spring receiving hole 2 (the second end 1b of the nozzle holder 1).
Side), rather than being disposed at a substantially central portion of the spring receiving hole 2 to detect the valve opening timing and the valve closing timing as described above, the end of the pressure pin 11 on the opposite side to the nozzle needle 7 should be positioned. It is not necessary to extend to the far end of the spring receiving hole 2, and the pressure pin 11 can be shortened. Therefore, the inertial mass of the moving part that moves at high speed is reduced, and the high-speed response of the fuel injection nozzle A can be improved. Moreover, since the pressure pin 11 does not penetrate the first spring 12 that urges the pressure pin 11,
When the spring 12 is made thinner, the pressure pin 11 is less likely to become an obstacle, so that the degree of freedom in spring design can be improved when the diameter of the nozzle A is reduced.

FIGS. 6 and 7 show a second embodiment of the present invention. This embodiment is basically similar to the first embodiment.
Since the configuration is the same as that of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description of the configuration and operation will be omitted, and only different points will be described below. The differences between the second embodiment and the first embodiment are the positions of the magnet and the mounting position of the detection coil on the magnet, and the configuration of the pressure pin and the gap serving as the magnetic resistance in the magnetic circuit.

That is, in the second embodiment, the magnet 23 has a ring shape, and one surface thereof (the surface on which the pressure pin 11 is lifted) has a pair of magnetic poles 23a,
23b is protruded. The two magnetic poles 23a and 23b have the same length and extend in the thrust direction of the pressure pin 11, and one of the magnetic poles 23a has an N pole and the other magnetic pole 2 has
The magnet 23 is magnetized so that 3b represents the south pole. The detection coil 24 has one of the magnetic poles, for example, the S pole 2
3b.

The pressure pin 11 made of a magnetic material omits the configuration corresponding to the large-diameter portion provided in the first embodiment, and penetrates the center hole of the magnet 23 to form a pair of magnetic poles 23a. 23b. The spring receiving portion 11a provided on the pressure pin 11 is opposed to the tip surfaces of the magnetic poles 23a and 23b as a magnetic pole facing portion, and a gap g is formed between them. Therefore, the gap g is provided in the thrust direction of the pressure pin 11. The configuration other than the points described above is the same as that of the first embodiment, including parts not shown in FIGS.

In the configuration of the second embodiment,
The magnetic flux emitted from the magnetic pole 23a on the N pole side of the magnet 23 flows through the gap g facing the magnetic pole 23a to the spring receiving portion (magnetic pole facing portion) 11a of the pressure pin 11 made of magnetic material. The magnetic flux flows into the magnetic pole 23b through the other gap g facing the magnetic pole 23b on the S-pole side from the receiving portion 11a and flows back. Therefore, a magnetic circuit of such a path is formed between the magnet 23 and the pressure pin 11.

The size of the gap g provided in the magnetic circuit in the thrust direction of the pressure pin 11 changes according to the axial movement of the pressure pin 11. That is, the gap g which is the magnetic resistance of the magnetic circuit
7B is small when the nozzle A is closed (when not lifted) as shown in FIG. 7B, and is large when the nozzle A is opened (when lifted) as shown in FIG. 7C.

Therefore, also in the second embodiment,
The magnetic flux passing through the detection coil 24 wound around the magnetic pole 23b of the magnet 23 changes according to the change in the magnetic resistance due to the gap g in the magnetic circuit that changes according to the axial movement of the pressure pin 11 linked to the nozzle needle, Since a voltage proportional to this magnetic flux change is generated in the detection coil 24 by electromagnetic induction, the lift of the nozzle needle is
The detection coil 24 can detect a change in the magnetic resistance in the magnetic circuit where 1 is a part of the magnetic path.

Therefore, also in the second embodiment, the lift of the nozzle needle 7 is detected by the detecting device 21 incorporated in the nozzle holder 1, and the same as in the first embodiment, the second embodiment of the present invention. The first and second problems can be solved respectively.

Moreover, in the second embodiment,
The spring receiving portion 11a and the magnetic pole facing portion may be provided separately, but since they also serve as these, there is no need to form a magnetic pole facing portion in addition to the spring receiving portion 11a. In combination with the omission of the large-diameter portion provided in the form, an increase in the inertial mass of the pressure pin 11 which is a part of the high-speed moving portion can be suppressed. Therefore, it is excellent in that high-speed response can be improved.

FIGS. 8 to 10 show a third embodiment of the present invention.

In the present embodiment, the detecting device 21 is not fixedly mounted on the intermediate portion of the pressure pin 11 such as the fuel injection nozzle shown in FIG. This is an example of a structure in which the detection device 21 is incorporated in a stationary state.

In this embodiment, the pressure pin 11
(A member in contact with the nozzle needle 7 and arranged in the axial direction) at the back of the first spring chamber 2d for accommodating the first spring 12 for urging the same.
That is, the detection device 21 is incorporated in the end opposite to the pressure pin 11 in a stationary state.

As shown in detail in FIG. 9, the detecting device 21 includes a cup-shaped case 30 made of a non-magnetic material.
A structure is used in which a plate-shaped magnet 31, a detection coil 34 formed by winding a coil wire 33 around a hollow bobbin 32, and a highly magnetically permeable core 35 are combined.

More specifically, the following structure is used for the detection device 21.

That is, the case 30 includes the first spring chamber 2d.
Has an opening on the upper side, and a core press-fitting hole 30a is drilled in the center of the bottom wall. The core 35 is formed of an umbrella-shaped stepped bar having a large diameter portion 36 and a small diameter portion 37 (corresponding to a protrusion) protruding from the center of the large diameter portion 36 and made of a highly magnetically permeable material. The detection coil 34 is inserted into the small diameter portion 37 of the core 35,
It is arranged on the base side of the small diameter portion 37. The small-diameter portion 37 into which the detection coil 34 has been inserted is pressed into the core press-fitting hole 30a from the opening side, and the detection coil 34 is sandwiched and fixed to the bottom wall of the case 30. With this fixation, the detection coil 34 is arranged in a direction in which the coil winding direction is aligned with the circumferential direction of the small diameter portion 37, and is built in the case 30. Magnets 31 each having a magnetic pole are arranged on the upper and lower surfaces so as to overlap the large diameter portion 36 of the core 35. This magnet 31
Are fixed by bolts 38 screwed into the large diameter portion 36 through the magnet 31. Thereby, the bolt 38, the magnet 31, the large diameter portion 36, the detection coil 3
4 fits into the detection device 21 having a structure in which the small-diameter portion 37 protrudes from the bottom of the case 30.

The case 30 accommodating these parts is inserted and mounted so as to fit into the inner end of the first spring chamber 12d (the end opposite to the side where the end of the pressure pin 11 is disposed). The small diameter portion 37 protruding from 30 is positioned so as to be coaxial with the nozzle needle 7. Case 3
0 on the outer surface of the bottom wall (the surface opposite to the detection coil 34)
A shim 39 for adjusting the valve opening pressure is arranged, and the case 30 is used as a spring seat. The case 30 is fixed by receiving the end of the first spring 12 with the shim 39. Thereby, the detecting device 21 is assembled in a stationary state at the end of the first spring chamber 2d. An O-ring 40 is interposed between the outer peripheral surface of the case 30 and the inner peripheral surface of the first spring chamber 2d, which oppose each other, and shields the fuel from excess fuel. The small diameter portion 37 protruding from the case 30 has a predetermined air gap g at its tip with respect to the end face of the pressure pin 11, here the end face of the small diameter shaft 11e protruding upward from the spring receiving portion 11a of the pressure pin 11. And the length dimension is set to be close to and opposed to each other.

Thus, similarly to the first and second embodiments described above, the change of the air gap g due to the movement of the pressure pin 11 can be determined by using the detector 21 mounted in a stationary state. The detection signal of valve opening / closing is output from the lead wire 25 connected to the detection coil 34.

That is, when the high pressure fuel injection from the fuel injection pump exceeds a certain setting, the nozzle needle 7 starts to rise due to the fuel pressure. Then, the pressure pin 11 in contact with the nozzle needle 7 also rises, and the air gap g becomes smaller than the initial state.

Here, since a magnetic circuit composed of the magnet 31, the core 35, the pressure pin 11, and the nozzle holder 1 is formed in the nozzle holder 1, the air gap g is reduced, so that the resistance of the magnetic circuit is reduced. The magnetic flux easily flows in the magnetic circuit, and the magnetic flux passing through the detection coil 34 increases.

At this time, a voltage is generated at both ends of the detection coil 34 so as to cancel the change in the magnetic flux passing therethrough according to Lenz's law. Of course, when the nozzle needle 7 descends, the opposite voltage is generated.

As a result, an output proportional to the speed of the nozzle needle 7 is generated. As in the case of the first embodiment, as shown in FIG. By comparing the valve threshold value V with the detection signal,
The injection timing of the fuel injection pump may be controlled by judging the valve opening.

In the structure in which the detecting device 21 is assembled at a position distant from the pressure pin 11, the first and second
The same effect as that of the embodiment can be obtained. The detection device 21
Since the magnet has a structure in which the magnetic poles are arranged at points away from the combustion chamber of the engine, there is an advantage that demagnetization of the magnet 31 due to high temperature can be reduced. In addition, the detecting device 21 includes the detecting coil 3 on the core portion disposed at the end of the first spring chamber 12.
4 and the magnet 31 is mounted immediately above the detection coil 34, so that not only the magnet 31 but also the detection coil 34 can be prevented from being affected by the high temperature. In addition, since the case 30 accommodating the detection coil 34 and the magnet 31 is used as the spring seat of the first spring 12 as it is, no additional member for forming the spring seat is required.

In FIGS. 8 and 9, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

[0074]

The present invention is embodied in the form described above and has the following effects.

According to the first to sixth and eighth aspects of the present invention, a voltage serving as a detection signal is generated by electromagnetic induction in a detection coil wound around the magnet in accordance with a change in magnetic flux of the magnet. The detection signal regarding the lift of the needle can be clearly generated to improve the reliability of the detection, and the configuration of the detection system is not complicated since a special converter is not required for the detection. In addition, since the detection device is built in the nozzle holder in a stationary state so that the force due to the high-speed movement of the pressure pin does not act on the magnet, there is no danger of the magnet falling off or being broken, and the pressure pin is magnetized. Since there is no need, various problems associated with magnetizing this pin can be eliminated, thereby improving the quality of the entire nozzle. Moreover, in the invention according to claim 8, since the magnetic poles of the magnet are arranged at points away from the combustion chamber of the engine, demagnetization of the magnet due to high temperature is small, and high reliability can be provided.

According to the seventh aspect of the present invention, a short pressure pin can be used and the inertial mass of the high-speed motion portion can be reduced.
High-speed response can be ensured, and furthermore, it is possible to prevent an increase in size.

According to the ninth aspect of the present invention, in addition to the above-described effects, the detection coil is disposed at a position away from the combustion chamber of the engine. Has the advantage that it can be avoided from the effects of high temperatures.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a control system for fuel injection according to the present invention.

FIG. 2 is a time chart for explaining detection of a valve opening timing and a valve closing timing of a fuel injection nozzle by a control system shown in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a configuration of a fuel injection nozzle according to the first embodiment.

FIG. 4 is a perspective view showing a relationship between a main part of a detection device provided in the fuel injection nozzle shown in FIG. 3 and a pressure pin.

FIG. 5A is a cross-sectional view taken along line ZZ in FIG. 5B. FIG. 5B is a cross-sectional view illustrating a relationship between a main part of the detection device illustrated in FIG. 4 and a pressure pin when a lift is not performed.
FIG. 5C is a cross-sectional view illustrating a relationship between a main part of the detection device illustrated in FIG. 4 and a pressure pin during a lift.

FIG. 6 is a perspective view showing a relationship between a main part of a detection device provided in a fuel injection nozzle and a pressure pin according to a second embodiment of the present invention.

FIG. 7A is a cross-sectional view taken along line YY in FIG. 7B. FIG. 7B is a cross-sectional view illustrating a relationship between a main part of the detection device illustrated in FIG.
FIG. 7C is a cross-sectional view illustrating a relationship between a main part of the detection device illustrated in FIG. 6 and a pressure pin during a lift.

FIG. 8 is a longitudinal sectional view showing a configuration of a fuel injection nozzle according to a third embodiment of the present invention.

FIG. 9 is an enlarged sectional view showing the periphery of the detection device shown in FIG. 8;

FIG. 10 is a time chart showing a detection signal output from a detection device according to a nozzle lift.

[Explanation of symbols]

 A: fuel injection nozzle, 1: nozzle holder, 2: spring receiving hole, 2d: first spring chamber (spring chamber) 7: nozzle needle, 11: pressure pin, 11a: spring receiving part (magnetic pole facing part), 11b ... Large diameter portion, 11c: Neck-shaped shaft portion, 11d: Step, 12: First spring, 13: Second spring, 21: Detection device, 22: Case, 23: Magnet, 23a, 23b: Magnetic pole, 24: Detection coil Reference numeral 30: case 31: magnet 34: detection coil 35: core 37: small-diameter portion (projection) 39: shim g: gap.

Claims (9)

[Claims] 1. A fuel injection nozzle in which a detection device for detecting a lift of a nozzle needle is incorporated in a nozzle holder, wherein the detection device is wound around the magnet built in the nozzle holder in a stationary state. And a pressure pin made of a magnetic material interlocking with the nozzle needle is passed between the two magnetic poles of the magnet, and the pressure pin is moved in a magnetic circuit extending over the magnet. Therefore, a fuel injection nozzle having a gap whose size changes. 2. The fuel injection nozzle according to claim 1, wherein the gap is provided in a radial direction of the pressure pin. 3. The apparatus according to claim 1, wherein said magnet is substantially U-shaped, and said detection coil is wound between both magnetic poles of said magnet to form said detection device. 3. The fuel injection nozzle according to claim 1, wherein a step is provided on the pin, and the size of the gap is changed by the step. 4. The fuel injection nozzle according to claim 1, wherein the gap is provided in a thrust direction of the pressure pin. 5. The pressure pin has a pair of magnetic poles protruding in the thrust direction of the pressure pin, and a magnetic pole facing portion facing the ends of the two magnetic poles is provided on the pressure pin. The fuel injection nozzle according to claim 1, wherein the gap is formed between the fuel injection nozzles. 6. The fuel injection nozzle according to claim 5, wherein the magnetic pole facing portion is formed by the spring receiving portion. 7. The apparatus according to claim 1, wherein said detecting device is disposed closer to said nozzle needle than a spring receiving portion of said pressure pin which receives a spring pressing said pressure pin against said nozzle needle. A fuel injection nozzle according to any one of the preceding claims. 8. An end of a pressure pin which is arranged in an axial direction with a nozzle needle in a spring chamber formed in a nozzle holder, and the end of the pressure pin is pressed by a spring housed in the spring chamber to press the nozzle needle. In a fuel injection nozzle incorporated in a detection device for detecting a lift of the nozzle needle in a nozzle structure for urging in a valve closing direction, the detection device is opposite to a side on which a pressure pin end of the spring chamber is disposed. A magnet incorporated in a stationary state at the end side of the nozzle, a core combined with the magnet, and a detection coil wound around the core, wherein the core is disposed inside the spring chamber with respect to the nozzle needle end. And a protruding portion protruding until the opposing member is opposed to the magnet, the core, the pressure pin, and the nozzle holder by the protruding portion. Ri forms a magnetic circuit, the fuel injection nozzle, characterized in that the change in the gap due to the movement of the pressure pin are configured to detect signals from the coil is output. 9. The detection coil has a wire wound around a core portion disposed on an end side of a spring chamber in a circumferential direction of the projection, and the magnet is located immediately above the detection coil. 9. The fuel injection nozzle according to claim 8, wherein the fuel injection nozzle is attached to a fuel injection nozzle.