JPH0370866A - Fuel injection nozzle for internal-combustion engine - Google Patents

Abstract

PURPOSE: To set pressure applied on a valve needle high even at a position in a partial load range by supporting at least two compression springs by a stopper moving with the valve needle and a shoulder part fixed on a casing. CONSTITUTION: As fuel pressure is increased to a release pressure P0 , a valve needle 16 starts releasing motion, and it compresses a compression spring 34 to which a weak pre-load is applied during a first half stroke hv1 to get to pressure P1 , when a shoulder part 42 of the valve needle 16 is applied to a stopper ring 44 to which a strong pre-load is applied by a compression spring 36. During the while, fuel of idle quantity is injected. Next, when pressure becomes P2 or over, a stopper sleeve 44 is moved up with the valve needle 16, the compression spring 36 is compressed while it is released for the first half storke hv2 , a push pin 48 is applied to a stopper pin 54, and as pressure rises up to P4 , it gets into a releasing stroke (h) against the compression springs 36, 34. Favorable injection characteristics can thus be obtained even in a low rotation number range.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a fuel injection nozzle for an internal combustion engine, in which a valve seat is formed in the valve body, and a valve needle is slidably supported. , a nozzle holder is provided, on which the nozzle body is fixedly clamped, the nozzle holder having two compression springs, the two compression springs displacing a stop and a valve needle, which are moved together with the valve needle. It is supported on a fixed shoulder of the housing and is of the type in which the resultant pressing force acting on the valve needle increases dramatically at the stroke position of the valve needle corresponding to the beginning of the partial load range.

[Conventional technology]

Known injection nozzles of this type (Swiss patent no.
29505), after the spring force has increased dramatically in the stroke position of the valve needle corresponding to the beginning of the partial load range, another spring force jump no longer takes place; It only increases linearly in response to the compression of the second compression spring acting alone.

Injection nozzles of this type operate satisfactorily in the idle link range, which is located under a unique spring force flow, and in this range a small injection cross section in the housing reaches a certain fuel quantity and therefore a certain fuel pressure. Only surfaces occur. In the part load range and in the full load range, the valve needle stroke increases proportionally to the fuel pressure and/or the speed; at high engine speeds it reaches a maximum value already in the part load range, which corresponds to the full valve needle travel. I'll reach it. However, taking into account the desire for as little noise generation as possible and other operational requirements, it is desirable that the valve needle only performs a full stroke over the entire load range and at high rotational speeds.

[Problems to be Solved by the Invention] An object of the present invention is to reduce noise generation at high rotational speeds in a fuel injection nozzle of the type mentioned at the beginning without deteriorating engine characteristic values at low rotational speeds.

[Means to solve the problem]

To solve this problem, the invention provides an arrangement in which at least two compression springs are supported on a stop that is moved together with the valve needle and on a shoulder fixed to the housing.
The pressing force acting on the valve needle is also significantly increased in the second stroke position located within the partial load range.

〔Effect of the invention〕

When configured as in the present invention, the following advantages can be obtained. This means that, especially at high speeds in the part load range, the stroke of the valve needle is limited, thereby extending the injection time, which has a particularly advantageous effect on the noise characteristics. By suitably matching the prestroke of the valve needle, the spring stiffness, and the spring brake load, it is possible to improve the behavior in the high speed range only at the expense of the properties at low speeds. A more advantageous injection characteristic profile than with known fuel injection nozzles of the type described is possible over the entire speed and load range.

The measures specified in claim 2 and below allow advantageous refinements of the arrangement specified in claim 1.

In order to implement a further pressure jump in the partial load range, for example, three compression springs are arranged concentrically, the two outer compression springs of these three springs being applied to the pressure piece. These pressure pieces are supported by stops fixed to the housing, and the valve needles rest one after the other on these pressure pieces. Such an arrangement has the advantage that the overall length of the target fuel injection nozzle is not enlarged, or only slightly enlarged. However, such an arrangement requires a significant increase in the diameter of the fuel injection nozzle, which is often not possible due to limited installation space.

If three closing springs are arranged and supported by the measures described in claim 2-51, a more elongated fuel injection nozzle configuration is obtained.

However, in this case, as in the state of the art, two closing springs are arranged axially one after the other, so that the overall length of the fuel injection nozzle is expanded accordingly.

A particularly advantageous configuration is obtained by the measures specified in claims 6 to 81. With these measures, the desired multi-step characteristic curve of the opening stroke of the valve needle can be obtained using only two compression springs, and in this case with considerable constructional over-expenses and less than the state of the art. No large space requirements are necessary.

A configuration according to the invention provides, inter alia, a quantity-controlled or flow-cross-section controlled fuel flow system with a valve needle opening inwardly against the fuel flow and an injection hole extending from the valve seat surface. The injection characteristic curve of the injection nozzle can be advantageously influenced.

〔Example〕

Six embodiments of the invention will now be explained in detail with reference to the drawings.

The fuel injection nozzle according to the first embodiment shown in FIG. 1 has a nozzle body 10 which is fixedly fastened to a nozzle holder 14 by a cap nut 12.

A valve seat (not shown) is formed in the nozzle body 10, in which a valve needle 16 is slidably supported. This valve needle has a complete pressure-receiving surface 18 in the area of a pressure chamber 20, which comprises a nozzle body 10 and a nozzle holder 1.
It is connected via holes 22, 24 and 26 provided in the nozzle holder with a connecting piece 28 for the fuel supply conduit provided in this nozzle holder. A chamber 30 is formed in the nozzle holder 14 and is open towards the nozzle body 10 , in which a compression spring device (
(described in detail below) are stored. The chamber 30 is connected to a leakage oil connection 32 for channeling off the fuel leaking through the guide hole of the valve needle 16 in the nozzle body 10 .

The compression spring device accommodated in the nozzle holder 14 consists of a first compression spring 34 and a second compression spring 36, which are arranged one after the other in the axial direction. The first compression spring 34 acts via a pressure piece 38 on a journal 40 of the valve needle 16 , which transitions into the guide section of the valve needle 16 at a shoulder 42 . The journal 40 passes through a stopper sleeve 44 with a bottom clearance, which is slidably guided within the chamber 30 of the nozzle holder 14 and surrounds the first compression spring 34. The upper end of the first compression spring 34 rests on a pressure pin 48 with a barb 46, the free end of which presses against the pressure piece 38 in the closed position of the valve needle 16. The distance a corresponds to the total stroke hg.

The pressing pin 48 itself is supported by a disc-shaped annular body 50, which is pressed against the upper end surface of the stopper sleeve 44 by the second compression spring 36. In this case, the second compression spring 36 is connected to the annular collar 5 of the stopper pin 54.
2 at the bottom of a chamber 30 provided in the nozzle holder 14. The second compression spring 36 presses the stopper sleeve 44 against the upper end surface 56 of the nozzle body 10 via the annular body 50 . The stopper sleeve 44 is provided with an external recess 58 at its bottom, on the bottom of which the shoulder 42 of the valve needle 16 abuts when the valve needle advances through its forward stroke hvxk. The free end of the barbed pin 54 is located at the closed position of the valve needle 16 and the push pin 48
In contrast, it has a distance corresponding to a predetermined second pre-stroke 11v2.

Next, the operation type of the fuel injection nozzle according to the first embodiment will be explained with reference to the curve diagram in FIG. This curve diagram shows the relationship between the opening stroke of the valve needle 16 and the fuel pressure P in the pressure chamber 20.

The fuel pressure reaches the predetermined opening pressure P5! When raised at , the valve needle 16 begins its opening movement. The next first pre-stroke h
During '/1, only the first compression spring 34 with a weak preload acts on the valve needle 16. When the fuel pressure reaches the value Pl, the valve needle 16 rests with its shoulder 42 on a stop sleeve 44, which is then strongly preloaded by the second compression spring 36.
is loaded by The compression spring 34, which is determined together with the prestroke hvl_k, and the opening course depending on the stroke of the valve flow cross section are coordinated with each other in such a way that a predetermined idling amount of fuel is injected until the average rotational speed is reached.

After the valve needle 16 has abutted against the stop sleeve 44, the fuel pressure must rise above the value P2, and then the valve needle 16 continues its opening movement. In this case, the stopper sleeve 44 together with the annular body 50
is shifted upward against the force of the compression spring 36. During this movement, the pressure pin 48 remains in contact with the annular body 50 with its collar 46, i.e. the first compression spring 34 can no longer be compressed, so that the preload of this first compression spring is lower than the valve needle 16. will no longer work. When the fuel pressure increases by 1 to P3 and the stopper sleeve 44 advances through the stroke hvz in this case, the pressure piston 48 abuts with its collar 46 against the stopper pin 54. The open position of the valve needle 16 obtained in this case results in a valve flow cross section that results in engine characteristic values that are advantageous for this operating range.

After the pressure pin 48 abuts the stop pin 54, the fuel pressure must first rise to the value P4, which then subsequently moves the valve needle 16 into its fully open position. be able to. One! During the remaining stroke, both compression springs 36 and 34 compress the nozzle holder 1.
4 or on the casing-fixed shoulder of the stop pin 54, which acts on the valve needle 16 in the closing direction. When the pressure piece 38 that has been moved together with the valve needle 16 comes into contact with the pressure pin 48 and this pressure pin itself contacts the stopper pin 54, the complete opening stroke hg of the valve needle 16 has been carried out. . During the closing movement of the valve needle 16, the operating steps take place in the reverse order.

By providing the second pressure stage P 3 / P 4, the valve flow cross section is not completely opened at high speeds in the part load range, but instead a longer injection time is forced; This has an advantageous effect on the noise characteristics. This advantageous effect can be achieved without arranging a third compression spring and only during the first stroke h on the valve needle.
At v□, only the first compression spring 34 acts, and at the second stroke hV2, only the second compression spring 36 acts,
The remaining residual stroke is achieved by simply activating both compression springs 34 and 36.

In the fuel injection nozzle according to the second embodiment shown in FIG.
The first compression spring 34 , which acts on the valve needle 16 via the pressure piece 38 , is supported on a disc-shaped annular body 60 , which itself rests on the annular collar 62 of the pressure pin 64 . This annular collar 62 is pressed against the stopper sleeve 66 via the annular body 60 by the second compression spring 36a, and this stopper sleeve itself is attached to the nozzle body 1.
It is supported on the upper end surface of 0.

In this fuel injection pump, as in the case of the previous embodiment, the first compression spring 34 actuates during the pre-stroke 'nv1 of the valve needle 16, and during the next second pre-stroke hv2. Only the second compression spring 36a acts, and then in the residual stroke both compression springs 34 and 36a, so that in this embodiment also only two compression springs are used. is obtained.

In detail, the following operation process is performed.

The trench valve needle 16 is connected to the pressing pin 64 via the pressing piece 38.
, so that the first compression spring 34 is no longer compressed, and the valve needle 16 is actuated simply by lifting the pressure spring 36a against the second compression spring 36a. The annular body 60 is the chamber 30 of the nozzle holder.
21, both compression springs 34 and 36a are again fixedly supported by the casing.
They act on the valve needle 16 independently of each other.

After the press 2-in 64 has advanced a distance b'2, the stopper pin 54
, the complete opening stroke of the valve needle 16 has been completed.

In the fifth embodiment shown in FIG. 4, a first compression spring 70 constantly acts on the valve needle 74 via a central pressure pin 72. The valve needle is slidably mounted in a nozzle body 76 which is connected to an intermediate plate 78.
It is fixedly tightened to the nozzle holder 80 together with the nozzle holder 80. A pressing piece 82 and a flanged sleeve 84 are slidably supported on the pressing shaft 72 so as to overlap with each other. The pressing piece 82 is located within a stepped hole 86 provided in the intermediate plate 78 and has an annular shoulder 88 on its outer peripheral surface. This annular shoulder, together with a corresponding shoulder 90 provided in the stepped bore 86, limits the total travel hgf of the valve needle 74. Pressing piece 8
2 is provided with a turned part 91 on the lower surface, and the bottom surface of this turned part extends a predetermined forward stroke hvl with respect to the flat end surface 74a of the back side of the valve needle 4 in the closed position.
The sound is over the distance equivalent to .

A chamber 92 is formed in the nozzle holder 80 , which transitions at an annular shoulder 93 into a second chamber 94 of smaller diameter with a first compression spring 70 . l in room 92
A second annular shoulder 95 is formed on the stopper sleeve 96 which guides the flanged sleeve 84 at a distance of 100 m, which rests on the intermediate plate 78.

The outer annular edge of an annular plate 97 is axially movable between the laminar shoulders 93 and 95 and carries a second compression spring 98 acting on the flanged sleeve 84. . The annular plate 97 has a first compression spring 70 at its upper part.
A third compression spring 99 concentrically surrounds the second chamber 94 and is supported at the bottom of the second chamber 94, and this fifth compression spring is preloaded to a greater degree than the second compression spring 98. The annular plate 97 is pressed against the stopper sleeve 96. In the illustrated closed state of the valve needle 740, the upper end surface of the flanged sleeve 84 extends from the annular plate 97.
They are separated by a distance corresponding to a predetermined second pre-stroke hy2.

The fuel injection nozzle shown in FIG. 4 operates as follows.

When the fuel pressure increases, the valve needle 74 operates only against the first compression spring 70;
travels a distance hVl and comes into contact with the lower part of the pressing piece 82. Thereafter, the valve needle 74 or the fuel pressure acting on it must also overcome the reaction force of the second compression spring 98. The reason is that when the valve needle 74 moves upward, the pressing piece 82 and the flanged sleeve 84
is also moved upwards, but the annular plate 97 is -11 still in contact with the annular shoulder 95 under the influence of the strongly preloaded third pressure spring 99.

When the valve needle 74 has advanced through a second forward stroke hvzt, the flanged sleeve 84 rests on the underside against the annular plate 97, so that the influence of the second compression spring 98, which is no longer compressed in this case, is interrupted; Fuel pressure is applied to the first compression spring 7
0 and the fifth compression spring 99, and in this case the third compression spring
It exerts a higher closing force than the compression spring 98 of . At the end of the remaining stroke of the valve needle 4, the pressure piece 82 rests on a corresponding shoulder 90 of the intermediate plate 78, which limits the opening stroke of the valve needle.

[Brief explanation of drawings]

The drawings show three embodiments of the fuel injection nozzle according to the present invention, in which FIG. 1 is a longitudinal sectional view of the fuel injection nozzle according to the first embodiment, and FIG. 2 is a longitudinal sectional view of the fuel injection nozzle shown in FIG. 1. FIG. 3 is a longitudinal sectional view partially showing the fuel injection nozzle according to the second embodiment, and FIG. 4 is a characteristic curve diagram showing the relationship between the opening stroke of the valve needle and the fuel pressure P in the pressure chamber. FIG. 2 is a longitudinal sectional view partially showing a fuel injection nozzle according to an embodiment.

Claims (1)

[Claims] 1. A fuel injection nozzle for an internal combustion engine, which is provided with a nozzle body, a valve seat is formed in the nozzle body, and a valve needle is slidably supported. , further provided with a nozzle holder to which the nozzle body is fixedly fastened, the nozzle holder having two
It has two compression springs, and these two compression springs are
A stop that is moved together with the valve needle is supported on a fixed shoulder of the casing, in which case the resultant pressing force acting on the valve needle jumps at the stroke position of the valve needle corresponding to the beginning of the partial load range. In the type with a high height, at least two compression springs (34, 36
; 70, 98) are moved together with the valve needle (16; 74);
64; 72, 84, 97) and a shoulder fixed to the casing (14, 56; 76, 80), the pressure force acting on the valve needle (16; 74) is located within the partial load range. A fuel injection nozzle for an internal combustion engine, characterized in that the height increases dramatically even at the second stroke position. 2. Valve needle (74) is always connected via pressing pin (72)
A first compression spring (70) is provided which acts on the
Moreover, after the first pre-stroke (h__v_1), a second compression spring (98) which acts on the valve needle (74) in addition to the first compression spring (70) surrounds the pressure pin (72). 2nd
The first compression spring (70
) acting additionally on the valve needle (74).
Fuel injection nozzle according to claim 1, characterized in that the compression spring (99) surrounds the first compression spring (70). 6. The second compression spring (98) is attached to the nozzle holder (80)
It acts on the flanged sleeve (84) which is guided inside and guides the pressing pin (72), and the flanged sleeve is guided in the first pre-stroke (h_v_1).
between the nozzle body (76) and the nozzle holder (80).
The flanged sleeve (84) or the further pressure piece (82) is supported in the closed position of the valve needle (74), either directly or via a further pressure piece (82), on the end face facing towards the
) and a shoulder (74a) of the valve needle (74) with a play corresponding to the first prestroke (h_v_1). 4. The flanged sleeve (84) is supported by the nozzle body (76) via a pressing piece (82), and the pressing piece is an intermediate portion tightened between the nozzle body (76) and the nozzle holder (80). supported on a plate (78), the intermediate plate (78)
4. A fuel injection nozzle as claimed in claim 3, characterized in that the opening stroke of the valve needle (74) is limited in cooperation with a shoulder (90) provided on the valve needle (74). 5. The second compression spring (98) is supported by the annular plate (97) surrounding the pressing pin (72),
The annular plate is pressed against a stopper (95) fixed to the casing by a third compression spring (99) to which a stronger preload is applied.
), and the valve needle (74) is pressed against the annular plate (97) on both front strokes (h_v_1, h_v
Claim 6, wherein the flanged sleeve (84) comes into contact with the flanged sleeve (84) when the flanged sleeve (84) advances through a partial stroke corresponding to the sum of _2).
or the fuel injection nozzle described in 4. 6. The first compression spring (34) acting on the valve needle (16) via the pressing piece (38) is connected to the first support member (48);
60), and the first support member receives the action of the first compression spring (34) to cause the second support member (50;
64), the second support member being preloaded with a higher preload than the first compression spring (34). The shoulder (42) or the pressure piece (38) of the valve needle (16) is pressed against the stopper shoulder (56; 66) of the valve needle (16) during the first pre-stroke (h_
v_1) indirectly or directly after the second support member (
50; 64), and the second compression spring (36; 36)
a) is adapted to lift the second support member from a first stopper shoulder (56; 66) fixed to the casing while compressing the second support member; is provided on the second stop shoulder with a second pre-stroke (h) of the valve needle (16).
_v_2) a first support member (48; 60) abuts, thereby causing both compression springs (34, 36; 34, 36
2. Fuel injection nozzle according to claim 1, wherein a) exerts a closing force on the valve needle (16). 7. The first support member (60) is a disc-shaped annular body,
The second support member (64) is a push pin that extends through the first support member (60) in contact with the first support member (60) with an annular collar (62); With the end in the closed position of the valve needle (16), the first prestroke (h_v
__1), and furthermore, both stopper shoulders (68, 66) fixed to the casing are located on the outer annular edge of the first support member. Corresponding stopper shoulders are formed in the hole step (68) provided in the nozzle holder (14a) and in the stopper sleeve (66) inserted in the nozzle holder (14a), In addition, the valve needle (
7. Fuel injection nozzle according to claim 6, characterized in that a stop pin (54) limiting the total stroke (h_v_1+b) of 16) is arranged in the second compression spring (36a). 8. The first support member (48) is a push pin with an annular collar (46) and extending inside the first compression spring (34), the free end of the push pin being connected to the valve needle ( 16), the pressing piece (38) is placed at a distance (a) corresponding to the full stroke (hg) of the valve needle (16).
), and the second support member (50) is a disc-shaped annular body, and the annular collar (46) of the first support member (48) is located opposite the second support member (50). 1 compression spring (34);
A second compression spring (36) with a stronger preload than the compression spring (34) of the second support member (50)
is pressed against the stopper sleeve (44), which in turn is pressed against the end face (56) of the nozzle body (10) facing towards the nozzle holder (14), and in addition a shoulder provided on the valve needle (16). portion (42) abuts against the stopper sleeve (44) after the first pre-stroke (h_v_1), after which the stopper sleeve is compressed by the second compression spring (
36) It is designed to shift against the force,
Furthermore, a stop pin (54) is arranged in the second compression spring (36), limiting the total stroke (hg) of the valve needle (16) and the stroke of the first support member (48); The fuel injection nozzle according to claim 6. 9. The fuel injection nozzle according to any one of claims 1 to 8, wherein the valve needle is configured to open inward against the fuel flow, and the injection hole extends from the valve seat surface. .