JPS6098162A - Fuel injection nozzle - Google Patents

Abstract

PURPOSE:To prevent an engine from the occurence of noises in the running region of low speed and load by providing piezo-electric elements in series with a coil spring for closing a needle valve in a fuel injection nozzle to control the valve opening pressure and lift of the needle valve with high accuracy. CONSTITUTION:When high pressure fuel is forcibly sent from a fuel injection pump 15 to a fuel injection nozzle 1 and fuel pressure reaches the valve opening pressure of a needle valve 7, the lift of the needle valve 7 is started so that a coil spring 10 is compressed through a press pin 8 to increase pressure acting on a piezo-electric element 11 and produce compressive strain and electric charge corresponding to the size of the compressive stains is generated. That charge is sent to a control circuit 20 as a voltage signal, and in the control circuit 20 the control signal voltage applied to the piezo-electric element 11 is gradually reduced. Thus, the piezo-electric element 11 gradually returns tensile strain to the initial one and the needle valve 7 is pushed up by the fuel presssure to open a nozzle hole 5 and inject fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an F&I engine in a diesel engine, etc. 3
Regarding the fuel injection q.1 nozzle used in 1st grade.

Line type or distributed type combustion 1! The fuel nozzle that injects the fuel supplied from the S sword pump into the combustion chamber of the engine generally uses the supply pressure of fuel to lift the needle valve against the coil splash, thereby opening the nozzle hole. It is configured to have a frontage and inject fuel 1. by the way,
The fuel nozzle of this scale has a constant value between the needle valve pressure and its 71~, so in the low speed and low load operating range of the engine, the fuel 111! A relatively large amount of fuel leaks into the combustion chamber before the injection pressure reaches the valve opening pressure, and as a result, fuel injection occurs at low pressure, resulting in atomization of fuel 1'31. As a result, engine vibration and noise increased during idling, resulting in poor drivability and white smoke from 111 gas, which became a problem.

゛ For this reason, a laminated piezoelectric element is incorporated inside the coil spring that biases the needle valve, and by applying a controlled voltage to this piezoelectric element, the fuel 1 is expanded and the closing horn of the needle valve is controlled. The l'l sword nozzle was developed in 1977.
It is proposed by Publication No. 160967@.

However, the above-mentioned injection nozzle directly presses the 21 dolb r due to the elongation strain of the vJ layer piezoelectric element, and its rifts 1 to 1
Since the elasticity of the spring cannot be effectively used to control the opening pressure of the needle valve, there is a problem that the opening pressure of the needle valve cannot be controlled smoothly and with high precision.

In view of the point described in 1., the present invention enables smooth and highly accurate control of the opening pressure and lift of the needle valve, and particularly in the low speed and low load operating range of the engine, vibration and noise generation. The purpose of this invention is to provide a fuel injection nozzle that can prevent this and ensure good drivability.

To this end, the present invention includes a needle valve that opens and closes a nozzle hole, and a coil spring that biases the needle valve in the closing direction, and the needle valve is injected by the fuel supply pressure. +11'llll] At the J nozzle,
The present invention is characterized in that a piezoelectric element (II) is arranged in series with the coil spring to control the opening pressure of the needle valve by changing the compression cart of the coil spring.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 mainly shows a cross-sectional view of a fuel injection nozzle used in a fuel injection system of a Deville engine. The fuel injection nozzle 1 is constructed by integrally connecting a holder body 2, a spacer 2a, and a nozzle body 3 with a tightening nut 4, and a center hole is bored in the axial direction inside the spacer 2a in the nozzle body 3. When the nozzle hole 5 is formed at the tip of the
(An oil reservoir 6 is formed directly above the nozzle hole 5 in communication with it.)

A suppression bottle 8 and a needle valve 7 are fitted into the center holes of the nozzle body 3 and the spacer 2a so as to be able to slide up and down, and the needle valve 7 is pushed downward by the pressure bottle 8 into the C nozzle hole 5. Sit on the stepped valve seat and close the valve. On the other hand, a shear spring chamber 9 is formed inside the holder body 2 and communicates with the center hole.
When the coil spring 10 that biases the needle valve 7 in the closing direction is inserted into the spring chamber 9 via the suppression pin 8,
A piezoelectric element 11 is located between the end of the coil spring 10 and the inner wall.
is interposed, the piezoelectric element 11 is connected in series to the coil spring 10, and the cart of the coil spring 10 is directly applied to the piezoelectric element 11. This piezoelectric element 11 uses a piezoelectric element that produces both the piezoelectric effect that generates an electric charge when it is subjected to a load and generates a strain, and the piezoelectric reverse effect that causes a strain and expands in response to the application of an electric current I. It is connected to the input/output side of the control 11x820, which will be described later, via a lead wire. 12 is F at the top of the fuel 1"11g 1 injection nozzle 1,
ah) The fuel is pumped into the oil sump 6 through the fuel passage 13 provided in the holder body 2, the spacer 2a, and the nozzle body 3 using the fuel introduction boat provided. On the other hand, introduction boards 1 to 12
A morning type or distribution type fuel injection pump 15 is installed externally.
The M size pipe 14 connected to is connected. A leak boat 16 is provided in the middle of the fuel injection nozzle 1 and communicates with the spring chamber 9. When the fuel in the oil sump 6 leaks into the spring chamber 9 through the gap around the needle valve 7, Return the leaked fuel to the fuel tank through a leak pipe (not shown). Incidentally, the space v2a regulates the maximum riff 1~ of the twenty-one dollar t7.

The control 1 circuit 20 includes a rotation sensor 21 provided in the engine or the fuel injection pump 15, 4i Indicating the engine condition from center point 22 J detection (ii) IH is manually operated, and based on this detection signal, a control signal is output to the FF electric element 11, and the opening/closing state of the needle valve 7 of the fuel injection nozzle 1 is determined. In particular, an engine electronic control system using a known microcomputer is configured to control the valve opening pressure at low speeds and low loads, and for example, comprehensively controls the fuel injection point and injection timing of the engine. Can be configured as part.

Next, the 28 operations of this fuel injection nozzle 1 will be explained.

First, to briefly explain the operation of the piezoelectric element 11, the piezoelectric element 11 is operated by the control circuit 20 under the control signal IJ11.
Depending on the signal voltage, iJ' J, sea urchin distortion lυ shown in Figure 2
The initial load of the coil spring 10, that is, the fishing wheel that closes the needle valve 7, increases as the voltage increases.

Note that in a normal state, a predetermined control signal is sent from the control circuit 20 to the piezoelectric element 11, and the 1.1E electric element 11 receives a predetermined f.
fi 1. :t) The spring horn of the coil spring 10 is expanded, and the opening pressure of the needle valve 7 is maintained at a high level. High-pressure fuel is pumped from the fuel injection valve 15 to the fuel injection nozzle 1 at a predetermined timing, passes through the fuel passage 13, reaches the oil sump 6, and acts on the needle valve 7. At this time, if the engine is in a low rotation and low load operating range, a signal is sent to the piezoelectric element 11 to increase the opening pressure of the needle valve 7 and promote atomization during fuel injection. Fuel injection control is performed as follows.

High-pressure fuel is sent from the fuel pump 15 to the fuel nozzle at a predetermined timing, this pressure is applied to the oil reservoir 6, and the fuel pressure is equal to the lift pressure of the needle valve 7. When the valve pressure is reached, the rift 1- of the needle valve 7 is started, which compresses the coil spring 10 via the pressure pin 8, so that the pressure acting on the piezoelectric element 11 increases and the pressure is increased. The electric element 11 generates compressive strain and generates an electric charge corresponding to the magnitude of this compressive strain.Piezoelectric element 1
The charge generated by the photon 1 is sent as a voltage signal to the control circuit 20, and the control circuit 20 gradually lowers the Qi pressure applied to the piezoelectric element 11 in response to the J signal voltage of this person. In addition, the pressure electrons gradually widen the strain at the center, the spring force of the coil spring 10 becomes weaker, the needle valve 7 is pushed up by the fuel pressure, and the nozzle hole 5 is spaced. Fuel injection takes place.

Mo II IIJI 111 from QJ pump 15! i
When the pressure feeding of ff3+ is finished, the pressure in the oil sump 6 decreases,
The needle valve 7 begins to descend due to the urging force of the coil spring 10. At this time, the coil spring 10 expands and the spring force decreases, causing the pressure applied to the piezoelectric element 11 to decrease, so that the J1 electric cord 11 is now subject to an opposite charge due to its return strain. , this charge is sent to the control circuit 20 as a voltage signal. In other words, the control circuit 20 sends a control signal that causes the piezoelectric element 11 to extend again to the ff wire 11.
The piezoelectric element 11 compresses the coil spring 10 which causes extensional strain, and the increased spring force moves the needle valve 7 in the closing direction, rapidly closing the nozzle hole 5 and preventing secondary injection. .

The elongation of the piezoelectric element 11 and the spring force of the coil spring 10 due to such a movement between the needle valves 70 and 111 change as shown in FIG. can be controlled independently.

Therefore, in low rotation and low load operating ranges such as when the engine is idling, the valve pressure of the needle valve 7 is increased as described above based on the detection signals sent from the rotation range 21 and the load range v22. Flil IJJ can be performed, and as a result, fuel 1'+1 can be injected with a sufficiently high pressure horn even at low rotation speeds and 11 (load).
The fuel is reliably atomized during injection, resulting in good combustion and smooth low-speed operation without noise or vibration.

In addition, in the above embodiment, the piezoelectric element 11 is
Although the piezoelectric element 11 is inserted between the end of the spring chamber 9 and the inner wall of the spring chamber 9, as shown in FIG. The action and effect of is 1q.

As explained below, in the fuel +1111 nozzle of the present invention, a low electric element is arranged in series with a coil spring for biasing the IJJ chain direction of the needle valve, and the compressive load of the IJJ chain is reduced. Directly changes the μ needle valve opening f, which controls the i horn. J: So, the engine's (L(
When the injection pressure angle decreases at high speed and low load, the opening force of the knee 1 hell valve is increased, and the lift 1 of Iζ is restricted to a small level to reduce fuel nr'J IJJ I from the nozzle hole.
: It increases the power and promotes the atomization of the fuel during use, resulting in better combustion. can be done.

[Brief explanation of the drawing]

The figure shows an embodiment of the present invention, and Figure 1 is a diagram showing the 4i structure of the fuel injection nozzle and its relationship with peripheral equipment.
Figure 2 is a graph showing the relationship between the applied electric current 1 and the amount of strain on the piezoelectric element, and Figure 3 shows the change in the strain of the 1-element element and the spring force of the 1-el spring when the knee and 1 nil valves are opened. Graph, Figure 4 (, l
FIG. 7 is a sectional view showing a side road according to another embodiment of the present invention. 1.1'...Fuel injection nozzle 5...Nozzle hole 7...Needle valve 8...Suppression bottle 9...Spring chamber 10...Il spring 11...J1 electric element allowance 111 ! Person Patent attorney Tsutomu Setatetsu and 1 other person Figure 1□2. Figure 3 Figure 1 (7 28

Claims (1)

[Claims] A fuel injection nozzle comprising a needle valve that opens a nozzle hole and a coil spring that urges the needle valve in a closing direction, and injects soot 11 by pressing the needle valve with fuel supply pressure, A fuel injection nozzle characterized in that a piezoelectric element is arranged in series with the coil spring to control the valve pressure of the needle valve by changing the compression load of the coil spring.