JPH03182681A - Fuel injection nozzle - Google Patents

Abstract

PURPOSE:To reduce the generation of machine noise by disposing a damping steel sheet on a contact surface between a holder in a needle slide direction and an intermediate plate or a contact surface between the intermediate plate and a nozzle body or a contact surface between the outer peripheral surface of a nozzle and the mounting hole of a cylinder head. CONSTITUTION:A fuel injection nozzle 1 is inserted in a mounting hole 5a of a cylinder head 5 in a state that a retaining nut 8 being a large part and the outer peripheral part of a holder 6 are covered, except the small part on the tip side of a nozzle body 3, with a cylindrical sleeve 18 made of a damping steel sheet. By covering the outer periphery of the fuel injection nozzle 1 with the sleeve 18 made of a damping steel sheet, propagation of impact noise to the outside is suppressed, and the generation of machine noise during operation of the fuel injection nozzle 1 can be reduced. Further, a shim 19 made of a vibration absorbing alloy and a vibration absorbing alloy sheet 20 are disposed between a needle 4 and an intermediate plate 7 and between the tip surface of the needle 4 and the valve seat of the nozzle body 3, and the generation of impact noise during lift of a valve or during seating of the needle 4 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection nozzle for injecting fuel into an internal combustion engine.

[Prior art 1] A fuel injection nozzle injects high-pressure fuel sent from a fuel injection pump into the combustion chamber of an internal combustion engine (diesel engine), and consists of a nozzle body, a needle, and a holder for mounting on the cylinder head. Be prepared.

The needle is slidably housed within the nozzle body, and is biased toward the valve seat by a sliding ring housed in the holder. The tip surface of the needle contacts and separates from the valve seat of the nozzle body, thereby controlling the outflow of fuel injected from the nozzle hole opened at the tip of the nozzle body.

In addition, the sliding stroke of the needle (fi large lift amount) is determined by the intermediate plate installed between the nozzle body and the holder.
It is regulated by the abutment of the rear end surface of the needle.

[Problems to be Solved by the Invention] In recent years, the fuel consumption of engines has been reduced, and as a result, there has been an increasing demand for reductions in mechanical noise generated by functional parts installed in engines.

However, in conventional fuel injection nozzles, a large impact noise is generated when the tip end of the needle contacts (seats) the valve seat, or when the rear end surface of the needle collides with the intermediate plate. However, despite the above-mentioned requirement for reducing mechanical noise, there were problems as a noise source.

The present invention was made based on the above circumstances, and an object thereof is to provide a fuel injection nozzle with reduced mechanical noise.

[Means for Solving the Problems] In order to achieve the above object, a first invention provides a nozzle body including a nozzle hole for injecting fuel and a valve seat connected to the nozzle hole, and the nozzle body. a holder that accommodates a needle that is movable inside and closes the nozzle hole when its tip surface contacts the valve seat, and a biasing means that urges the tip surface of the needle toward the valve seat; an intermediate plate that is disposed between the nozzle body and the holder and that restricts the maximum stroke amount of the needle by abutting the rear end surface of the needle; and a cylindrical intermediate plate that fixes the nozzle body to the holder. Equipped with a retaining oak I,
In a fuel injection nozzle that is installed in a mounting hole formed in a cylinder head of an internal combustion engine through the holder, the contact surface between the holder and the intermediate plate in the sliding direction of the needle, or the contact surface between the intermediate plate and the intermediate plate in the sliding direction of the needle. The contact surface with the nozzle body, or between the outer circumferential surface of the fuel injection nozzle and the inner circumferential surface of the mounting hole of the cylinder head, or between the outer circumferential surface of the nozzle body and the inner circumferential surface of the retaining nut. The technical means is that a damping steel plate is provided to damp vibration energy generated due to the operation of the needle.

Further, the second invention includes a nozzle body including a nozzle hole for injecting fuel and a valve seat connected to the nozzle hole; a needle that closes the nozzle hole by contacting a seat; a holder that accommodates a biasing means for biasing a tip end surface of the needle toward the valve seat; and a holder disposed between the nozzle body and the holder. In the fuel injection nozzle, the fuel injection nozzle includes an intermediate plate that restricts the maximum stroke amount of the needle by contacting with the rear end surface of the needle, and between the tip surface of the needle and the valve seat of the nozzle body, or The technical means is that a vibration-absorbing alloy is disposed between the intermediate plate and the rear end surface of the needle to attenuate the collision noise caused by the operation of the needle.

[Function] The fuel injection nozzle according to the first invention uses a damping steel plate, so that when the tip end surface of the needle comes into contact with the valve seat,
Alternatively, the vibration energy generated when the rear end surface of the needle collides with the intermediate plate can be converted into thermal energy and attenuated.

This damping steel plate has a sandwich structure in which polyolefin resin, soft metal, etc. are sandwiched between hard metals such as steel plates, and the vibration damping steel plate undergoes shear deformation in response to vibrations, thereby attenuating the vibration energy and producing sound. This is to suppress the

Further, in the fuel injection nozzle according to the second invention, a vibration-absorbing alloy is directly disposed on the contact surface between the tip end surface of the needle and the valve seat, or the contact surface between the rear end surface of the needle and the intermediate plate. Therefore, the vibration-absorbing ability of the vibration-absorbing alloy suppresses the occurrence of collision noise.

Note that, as the vibration-absorbing alloy, for example, there is a steel material having an iron-based 13Cr-3Aj precept that has a vibration-proofing coefficient of 70% or more.

[Effects of the Invention] According to the first invention having the above-mentioned effects, by using the IIA steel plate, it is possible to suppress the harsh collision sound from being emitted to the outside due to the operation of the needle. Therefore, mechanical noise generated during operation of the fuel injection nozzle can be reduced.

Further, according to the second invention, by using the vibration-absorbing alloy, it is possible to suppress the collision a itself that occurs during the operation of the needle. It is possible to reduce noise.

[Example 2] Next, a fuel injection nozzle of the present invention will be explained based on an example shown in the drawings.

FIG. 1 is a sectional view of a fuel injection nozzle.

The fuel injection nozzle 1 injects high-pressure fuel sent from a fuel injection bonder (not shown) into the combustion chamber of a diesel engine. Figure 1 shows a hole nozzle used in a direct injection engine. .

The configuration of the fuel injection nozzle 1 of this embodiment will be explained below.

The fuel injection nozzle 1 includes a nozzle body 3 in which a nozzle hole 2 is formed at the tip (lower side in FIG. 1), a needle 4 housed in the nozzle body 3 to open and close the nozzle hole 2, and a cylinder head 5. and a holder 6 for attachment to the nozzle body 3.
However, the retaining nut 8 is inserted between the intermediate plate 7, which will be described later.
A suck hole 9 that communicates with the nozzle hole 2 and a fuel passage 10 that guides fuel to the suck hole 9 are formed inside the tip of the nozzle body 3. The tip of 10 is
It is formed as a conical valve seat 11 connected to the suck hole 9.

Furthermore, a fuel supply passage 12 , 13 is formed in the holder 6 and the intermediate plate 7 , which guides the fuel supplied from the fuel injection bong 1 to the fuel passage 10 of the nozzle body 3 .

The needle 4 is housed so as to be slidable in the axial direction (in the vertical direction in FIG. 1) with respect to the nozzle body 3, and is provided with a journal portion 14 and a brake pin 15 provided through the intermediate plate 7.
is urged toward the valve seat 11 by a spring (biasing means of the present invention) 16 housed in the holder 6. The biasing force of the sedge ring 16 is adjusted by a shim 17 provided at the rear end of the spring 16.

The needle 4 has a conical end surface and forms a seat portion between the needle 4 and the valve 811 of the nozzle body 3 . Therefore, since the tip end surface of the needle 4 is separated from the valve seat 11 of the nozzle body 3, the fuel led from the fuel passage 10 to the suck hole 9 is injected from the nozzle hole 2. Also,
When the tip surface of the needle 4 contacts (seats) the valve seat 11 of the nozzle body 3, communication between the fuel passage 10 and the suck hole 9 is cut off, and fuel injection from the nozzle hole 2 is stopped.

In addition, when the needle 4 is opened (when it is separated from the valve seat 11)
The sliding stroke amount (maximum lift, 1) in the intermediate plate 7 fixed between the nozzle body 3 and the holder 6,
This is regulated by the abutment of the rear end surface of the needle 4.

The retaining nut 8, which has a cylindrical shape, is provided with a shoulder portion 8a projecting toward the inner circumference at the tip end (bottom of Fig. 1 (!!lI)), and has a female thread 8b formed on the inner circumference of the rear end portion. .

Using the retaining nuts Nos. 1 to 8, while holding down the step 11 formed in the middle of the nozzle body 3 with the shoulder 8a, connect the male and female screws 68 formed on the outer periphery of the tip of the holder 6. 8h, the holder 6 and nozzle body 3 are fixed with the intermediate plate 7 in between.

Well, on the outer peripheral corner of the shoulder 8a of the retaining nut 8, there is a sawtooth step for fixing the collar 18a of the sleeve 18, which will be described later, between the cylinder and the mounting hole 5a of the rad 5. A notched portion 8C is formed with -) over the entire circumference.

The fuel injection nozzle 1 of this embodiment has a large diameter part, except for the small diameter part on the tip side of the nozzle body 3.
8 and the outer periphery of the holder 6 are covered with a cylindrical sleeve 18 made of vibration-damping steel plate, and the first hole 5 of the cylinder head 5 is
It is inserted in a.

Therefore, the mounting hole 5a of the cylinder head 5 has a small diameter fitting part into which the small diameter part on the tip side of the nozzle body 3 is inserted and opens into the combustion chamber, and a small diameter fitting part that opens into the combustion chamber, and the fuel injection nozzle 1 covered with the sleeve 18.
and a large-diameter fitting part into which the large-diameter part of the main body is inserted.

Further, the fuel injection nozzle 1 is mounted and fixed in the mounting hole 5a of the cylinder head 5 by, for example, screwing a flange portion (not shown) formed on the holder 6 to the cylinder head 5.

The sleeve 18 is formed with a flange-shaped flange 18a toward the inner circumference at the lower end in FIG. When fixed, as described above, the flange portion 18a connects the stepped notch 8C of the retaining nut 8 and the end surface 5b of the Ft difference between the small diameter fitting portion and the large diameter fitting portion of the mounting hole 5a. It is held in place by being sandwiched in between.

The damping steel plate forming this sleeve 18 has a sandwich structure in which plastic or soft metal is sandwiched between hard metals.
For example, polyolefin resin is applied to steel plate C.
``There is something sandwiched between them, and the resin undergoes abrasion deformation (shearing deformation) in response to vibrations, which can convert vibrational energy into thermal energy and attenuate it.

In order to sandwich and fix the flange 18a, the sleeve 18 has the thickness of the flange +8a equal to the depth of the stepped portion of the mounting hole 5a (from the end surface 5b of the stepped portion of the mounting hole 5a to the retaining nut 1). Step 8 (・iL to the inner surface of the Y cutout 8C
Although it is set slightly larger than [), fuel injection nozzle 1
The force during installation can be received by the shoulder portion 8a of the retaining nut 8. This makes the sleeve 18 shaped +I;-
The Young's modulus of the damping steel plate is smaller than that of normal steel plate, about 1
/6) Therefore, even if the flange portion 18a is sandwiched and the tightening is fixed, most of the mounting load will be applied to the shoulder portion 8a of the retaining nut 8, which does not have a stepped portion. By the way, the Young's modulus of damping steel plates is usually 2. The Young's modulus of resin is approximately 1,750 or less than that of steel, whereas it is approximately 1X10' kgf/l1m2. Therefore, if this resin material is sandwiched with a thickness of 10% of the total plate thickness, it will not work as a damping steel plate. has a Young's modulus of about 176 in the thickness direction of a normal steel plate.

Next, the operation and effects of the use of the damping steel plate sleeve 18 as well as the operation of the fuel injection nozzle 1 will be explained.

First, when injecting fuel, high-pressure fuel sent from a fuel injection pump passes through the fuel supply passages 12 and 13 formed in the holder and the intermediate plate 7, and the fuel passage 10 formed in the nozzle body 3. is supplied to the seat section via. As a result, the needle 4 is moved by the spring 1 due to the pressure of the fuel.
As the tip surface of the needle 4 separates from the valve seat 11 of the nozzle body 3, the high-pressure fuel flowing into the suck hole 9 flows into the combustion chamber from the nozzle hole 2. is injected into.

Thereafter, in the latter half of the fuel injection, the fuel pressure decreases, so the needle 4, which had been raised toward the intermediate plate 7, is pushed back toward the valve seat 11 by the biasing force of the spring 16. (7) The tip end surface of the needle 4 contacts (seats) the valve seat 11 of the nozzle body 3, thereby stopping fuel injection.

In the above operation, the needle 4, which rose by overcoming the biasing force of the spring 16 during fuel injection,
The rear end surface collides with the intermediate plate γ, causing a sudden stop. Therefore, when the needle 4 and the intermediate plate 7 collide, a large impact 1 is generated.

Furthermore, when the tip end surface of the needle 4 seats on the valve seat 11 of the nozzle body 3 in the latter stage of fuel injection, a large impact a called seating noise is also generated.

Here, in this embodiment, the mounting hole 5a of the cylinder head 5 is
By covering the outer periphery of the fuel injection nozzle 1 inserted into the interior with a damping steel plate sleeve 18, the transmission of the above-mentioned impact noise to the outside is suppressed, and the mechanical noise generated when the fuel injection nozzle 1 is operated is reduced. can be reduced.

Note that, as described above, the damping steel plate used for the sleeve 18 is not used for the part that supports the force when installing the fuel injection nozzle 1, and can effectively block noise with a simple cylindrical shape. . Therefore, the increase in cost due to the use of the sleeve 18 made of damping steel plate can be suppressed.

Note that although the damping steel plates forming the sleeve 18 are shown as having polyolefin resin sandwiched between the steel plates,
The same effect can be obtained by using mild steel such as aluminum, which has a Young's modulus of 7.2 x 10'kgf/u'', which is about 1/3 that of steel, instead of resin as the material to be sandwiched between the steel plates.

Furthermore, in this embodiment, in order to fix the sleeve 18,
The retaining nut 8 is provided with a stepped notch 8C for sandwiching the flange 18a of the sleeve 18. As shown in FIG.
A stepped recess 5C may be formed to sandwich the portion 8a.

Next, FIG. 3 shows a second embodiment of the present invention.

In this embodiment, a damping steel plate sleeve 18 is arranged on the inner circumferential side of the retaining nut 8, as shown in FIG.
It is sandwiched between the retaining nut 8, the nozzle body 3, and the intermediate plate 7.

The sleeve 18 has a flange 18a formed at the tip.
Four portions 8d4 formed on the inner surface of the shoulder portion 8a of the retaining nut 8 (four surfaces of the rear end of the shoulder portion 8a): are fitted and fixed between them and the end surface of the stepped portion 3a of the nozzle body 3. J3, the sleeve 18 is formed so that the thickness of the flange 18a is slightly larger than the depth of the fourth part 8d, and when the flange 18a is sandwiched and fixed, the sleeve 18 is deformed in the axial direction of the flange 18a. Reliable, or -) Can be easily fixed.

Also, in the case of this embodiment, as in the first embodiment, the force at the time of mounting the fuel injection nozzle 1 is applied to the shoulder 8a of the retaining nut 8 (the end surface of the stepped portion 3a of the nozzle body 3 and the mounting hole 5).
It can be received at the part sandwiched between the step part end face 5b of the part a.

Further, in this embodiment, when the valve 971~ the needle 4 is
A shim 19 made of a vibration-absorbing alloy is disposed on the rear end surface of the needle 4, which is the collision surface with the intermediate plate 7 (moving upward in the figure).

The shim 19 has an annular shape having approximately the same diameter as the diameter of the sliding portion of the needle 4 with the nozzle body 3, and is fitted onto the outer periphery of the journal portion 14.

This shim 19 is available in several types with different plate knobs every about 0.02111 m, and by appropriately selecting the thickness of the shim 19 (for example, about IIm), the maximum lift amount of the needle 4 can be adjusted to the desired value. Can be set to a value.

Furthermore, as shown in Figure 4 (enlarged view of the seat part),
A vibration-absorbing alloy plate 20 having a conical shape is also disposed on the tip end surface of the needle 4 constituting the seat portion or on the contact surface of the valve seat 11 of the nozzle body 3.

An example of a vibration-absorbing alloy is iron-based 13Cr381.
There are steel materials that contain components and have a vibration damping coefficient of 70% or more.

In this way, by arranging the vibration-absorbing alloy shim 19 and the vibration-absorbing alloy plate 20 between the needle 4 and the intermediate plate 7 and between the tip surface of the needle 4 and the valve seat 11 of the nozzle body 3, It is possible to reduce the collision noise generated when the needle 4 collides with the intermediate plate 1 during valve retardation or when the tip end surface of the needle 4 seats on the valve seat 11 of the nozzle body 3 in the latter stage of injection.

In addition, the mechanical noise generated when the fuel injection nozzle 1 is operated is further reduced by the synergistic effect of the reduction of collision noise by the vibration-absorbing alloy shim 19 and the vibration-absorbing alloy plate 20 and the sound insulation effect by the vibration-damping steel plate sleeve 18. can do.

Note that, in general, vibration-absorbing alloys tend to have a reduced damping ability due to vibration, and thus the effect of suppressing sound against impact is reduced. Therefore, when disposing the needle 4 between the tip surface of the needle 4 and the valve rg:11 of the nozzle body 3, the processing degree of the vibration-absorbing alloy is different from that when the vibration-absorbing alloy is disposed on the rear end surface of the needle 4. If the structure is a little more complicated than that and a noise damping effect cannot be expected, a vibration-absorbing alloy may be provided only on the rear end surface of the needle 4.

In addition, in this embodiment, in order to fix the sleeve 18,
The retaining nut 8 has a shoulder portion 8 a l' (a surface thereof has a fourth portion 8 d into which the collar portion 18 a of the sleeve 18 is fitted; however, as shown in FIG. You may form the step part 3b into which it fits.

Next, FIG. 6 shows a third embodiment of the present invention.

In this embodiment, as shown in FIG. 6, an annular plate 21 made of a damping steel plate is provided between the nozzle body 3 and the intermediate plate 7, or between the intermediate plate 7 and the holder 6, or both. The noise is reduced by sandwiching it between the two.

The part of the nozzle body 3, intermediate plate 7, or holder 6 where the annular grate 21 is sandwiched has a stepped shape with a step slightly smaller than the thickness of the annular brake 21 in order to securely fix the annular plate 21. It is formed.

Note that, as in the first and second embodiments, the force applied when installing the fuel injection nozzle 1 is received by the nozzle body 3 and the holder 6, so the annular plate 2 made of a vibration-damping steel plate is
It doesn't take 1.

(Modified Example) In the second embodiment, an example was shown in which a damping steel plate and a vibration-absorbing alloy were used together, but instead of using a vibration-damping alloy, only the sleeve 18 made of a damping steel plate was used as in the first embodiment. may be used to reduce machine noise. Alternatively, only a vibration-absorbing alloy may be used without using the sleeve 18 made of vibration-damping steel plate.

Note that in the first and third embodiments as well, the damping rRfjA plate and the vibration absorbing alloy may be used together, as in the second embodiment.

In the above embodiment, the fuel injection nozzle 1 is a Hall nozzle used in a direct injection type engine, but it goes without saying that a bottle type nozzle used in a pre-combustion chamber type or swirl chamber type engine may also be used.

[Brief explanation of drawings]

Figures 11 and 2 show a first embodiment of the present invention, where Figure 1 is a sectional view of a fuel injection nozzle, and Figure 2 is a sectional view showing a modification of the sleeve fixing method. . 3 to 5 show a second embodiment of the present invention, in which FIG. 3 is a sectional view of the fuel injection nozzle, FIG. 4 is an enlarged view of the seat portion, and FIG. 5 is related to the method of fixing the sleeve. It is a sectional view showing a modification. FIG. 6 shows a third embodiment of the present invention, and is a sectional view of a fuel injection nozzle. In the diagram 1...Fuel injection nozzle 2...Nozzle hole 3...
・Nozzle body 4...Two needles 5...
・Cylinder head 5a...Mounting hole 6...
Holder 7... Intermediate plate 8... Retaining nut 11... Valve seat 16... Spring (biasing means) 18... Sleeve (vibration damping steel plate) 19... Shim (vibration absorbing alloy) 20 ...Conical vibration-absorbing alloy plate (vibration-absorbing alloy) 21...
Annular grate (vibration damping steel plate)

Claims (1)

[Scope of Claims] 1) A nozzle body including a nozzle hole for injecting fuel and a valve seat connected to the nozzle hole; a needle that closes the nozzle hole by contacting a seat; a holder that accommodates a biasing means for biasing a distal end surface of the needle toward the valve seat; and a holder disposed between the nozzle body and the holder. an intermediate plate that restricts the maximum stroke amount of the needle by contacting with a rear end surface of the needle; and a cylindrical retaining nut that fixes the nozzle body to the holder, , in a fuel injection nozzle installed in a mounting hole formed in a cylinder head of an internal combustion engine, a contact surface between the holder and the intermediate plate or a contact surface between the intermediate plate and the nozzle body in the sliding direction of the needle. The needle is disposed between a contact surface, or between the outer circumferential surface of the fuel injection nozzle and the inner circumferential surface of the mounting hole of the cylinder head, or between the outer circumferential surface of the nozzle body and the inner circumferential surface of the retaining nut. A fuel injection nozzle characterized in that a damping steel plate is provided to damp vibration energy generated in conjunction with the operation of the fuel injection nozzle. 2) A nozzle body is provided with a nozzle hole for injecting fuel and is formed with a valve seat connected to the nozzle hole, and the nozzle body is provided so as to be slidable within the nozzle body, and the tip surface is in contact with the valve seat. a needle that closes the nozzle hole; a holder that accommodates a biasing means that biases a tip end surface of the needle toward the valve seat; and a holder that is disposed between the nozzle body and the holder, and that A fuel injection nozzle including an intermediate plate whose end surfaces abut, thereby regulating the maximum stroke amount of the needle, between the tip surface of the needle and the valve seat of the nozzle body, or between the intermediate plate and the needle. A fuel injection nozzle, characterized in that a vibration-absorbing alloy is disposed between the rear end face and the rear end face to attenuate collision noise caused by the operation of the needle.