WO2012102635A1

WO2012102635A1 - Electromagnetic valve for a hydraulically controllable fuel injector

Info

Publication number: WO2012102635A1
Application number: PCT/RU2011/000037
Authority: WO
Inventors: Борис Константинович ЗУЕВ
Original assignee: Zuev Boris Konstantinovich
Priority date: 2011-01-26
Filing date: 2011-01-26
Publication date: 2012-08-02
Also published as: RU2013134929A; RU2541483C1

Abstract

The electromagnetic valve for a hydraulically controllable fuel injector is intended for use in the fuel injection apparatus of internal combustion engines. The electromagnetic valve comprises an electromagnet, a tappet (5) which is spring-loaded in the opening direction of a magnetic circuit and is connected to a closing element (10), and an armature (4) of the electromagnet, said armature being mounted on the tappet (5) so as to be axially displaceable relative to the tappet (5) in the opening direction of the magnetic circuit and having a stop in the closing direction, wherein displacement of the armature (4) in the opening direction of the magnetic circuit is limited by an elastic element. According to the invention, the elastic element is in the form of an elastic disc (13) which is joined to the tappet (5) and the peripheral part of which disc is rigidly connected to the armature (4) with the formation of a damping cavity (14) between the end face of the elastic disc (13) and the armature (4), and the stop comprises an elastically deformable ring (6) which is fixed along the periphery in the armature (4) on the other side of the damping cavity relative to the elastic disc (13). The electromagnetic valve according to the invention has a simple, reliable design with reduced axial dimensions and permits control of increased fuel pressure without an increase in the power of the electromagnet.

Description

ELECTROMAGNETIC VALVE FOR HYDRAULIC CONTROL

FUEL INJECTOR

Technical field

The invention relates to engine building, in particular to fuel-spraying equipment for internal combustion engines.

State of the art

High pressure hydraulically controlled fuel nozzles typically comprise a control chamber with an outlet channel closed by a shut-off element by means of a pre-loaded main spring and opened by exciting an electromagnet to move the armature to overcome the force exerted by the spring. In known valves, for example in the electromagnetic valve of a fuel injector according to EP 0 604 914 A1, the armature is rigidly connected to a rod sliding inside a fixed guide.

When the outlet channel is closed, the kinetic energy of the armature and the rod is dissipated when the locking element hits the valve seat, and when the outlet channel is opened, the kinetic energy of the armature and rod backstroke is dissipated when the fuel is displaced from the gap between the armature and the magnetic circuit.

The impact of the locking element on the valve seat creates a significant force proportional to the mass and speed of movement of the armature and the rod and inversely proportional to the duration of the impact, which is very small, and, given the hardness of the rod, ball and valve seat, leads to a significant impact when closing the channel, so moving the armature does not ensure stable operation of the nozzle.

One suggestion for reducing the recoil of the mass that is stopped during the closing stroke is to disconnect the anchor from the rod and use a second spring, which is weaker than the main spring and is designed to press the anchor against the stop on the rod. This solution is implemented in the solenoid valve of the fuel injector according to patent EP 0753658 A1. Also, in said valve, the stem is provided with a flange enclosed inside a chamber in which fuel circulates and in which movement of the flange creates some turbulence to further reduce recoil when opening the exhaust channel. However, this design also has a certain drawback, namely, that the anchor after pressing the locking element to its seat subsequently begins to make transient vibrations. As a result of such oscillations, the armature after the preliminary injection takes an indefinite position, which during the subsequent main injection with the same duration of control actions can lead to different durations of the solenoid valve in the open state. Also, these vibrations can lead to re-opening of the valve.

To eliminate these drawbacks, a damping device is introduced into the design of the electromagnetic valve. For example, in the electromagnetic valve according to the patent RU 2209337, there is a damping device interacting with the anchor and the fixed element, which works with the displacement of the fuel, which damps the transient vibrations of the armature during its dynamic movement. The disadvantage of this design is the difficulty of ensuring a calibrated gap between the armature and the fixed element.

The control device of the high-pressure nozzle according to the patent US 6305355 is also known, in which the function of the damping device is performed by a massive body located coaxially with the armature and in contact with it from the side opposite to the electromagnet. In the reverse course, the anchor, after pressing the locking element against the saddle, collides with the massive body, transmitting its momentum to it and, accordingly, preventing its possible oscillations. The disadvantages of this design include the need to introduce additional elements into the design, which leads to its cost increase.

A common feature of all the mentioned structures with a movable armature is the presence of two guide surfaces on the rod. The first is the direction of the rod itself in a fixed sleeve fixed in the housing, the second is the direction of the movable armature along the rod. The presence of these two surfaces limits the minimum axial dimensions of the control valve.

The objective of the present invention is to eliminate the above disadvantages and create a simple, reliable solenoid valve for a hydraulic nozzle with reduced axial dimensions. Disclosure of invention

This problem is solved in an electromagnetic valve for a hydraulic fuel injector containing an electromagnet, a pusher spring-loaded in the direction of opening the magnetic circuit and connected to the locking element, an electromagnet armature mounted on the pusher with the possibility of axial movement relative to the pusher in the direction of opening of the magnetic circuit and having an emphasis in the side closure, and the movement of the armature in the direction of the opening of the magnetic circuit is limited by the elastic element. According to the invention, the elastic element is made in the form of an elastic disk combined with a pusher and rigidly connected with its peripheral part to the anchor with the formation of a damping cavity between the end of the elastic disk and the anchor, and the emphasis is an elastically deformable ring fixed along the periphery in the anchor on the other side of the damping cavity relative to the elastic disk.

The damping cavity may be in the form of a ring, an annular gap on the inner diameter of which forms the outlet section of the damping cavity.

Preferably, the axial dimension of the slit of the exit section of the damping cavity is 0.5 to 1.5 times the stroke of the pusher. A decrease in the axial size of the output section leads to an increase in the outflow velocity and, accordingly, to an increase in damping, however, the magnitude of the force transmitted from the armature to the rod increases. The specified range is a compromise between the amount of damping and the pressing force of the locking element to the seat.

Moreover, the ratio of the outer diameter of the damping cavity to the inner diameter is 1.8 - 3. Since the diameter of the outlet cross section is determined constructively, this ratio determines the area of the damping cavity. At a ratio of 1.8, it is minimal and fluid displacement requires less effort. When this ratio is increased to 3, the area of the damping cavity increases, and more force is required to displace the liquid from it, which increases the damping of the kinetic energy of the armature. Also, an increase in the diameter of the damping cavity leads to an increase in the deformation of the elastic disk of the pusher, which makes it possible to perform an elastic disk of greater thickness at the same strain value, increasing the manufacturability of its manufacture.

Preferably, the stiffness of the thrust ring is 2 to 5 times greater than the stiffness of the elastic disk. The specified range is selected from the conditions of collateral the necessary rigidity of fixing the anchor, moving under the action of the return spring, while the minimum value of the range determines the maximum lag of the armature from the pusher, and the maximum value of stiffness - the minimum lag.

The outer diameter of the thrust ring is equal to the diameter of the elastic disk, and the inner diameter is 1, 3 - 2 of the diameter of the pusher. The specified range is selected from the condition for ensuring the necessary rigidity of the anchor moving under the action of the return spring, as well as from the condition for ensuring the necessary size of the additional damping cavity between the elastic disk and the thrust ring, and the minimum diameter determines the minimum lag of the armature from the pusher and the maximum cavity size, and maximum diameter — maximum lag and minimum cavity size.

Features and advantages of the invention will be better understood from the further description of the preferred embodiment with reference to the attached drawings.

Brief Description of the Drawings

In FIG. 1 is a sectional view of a fuel injector comprising an electromagnetic valve according to the invention;

in FIG. 2 - remote element A in FIG. 1 on an enlarged scale;

in FIG. 3 - remote element B in FIG. 1 on an enlarged scale;

in FIG. 4 - remote element C in FIG. 1 on an enlarged scale;

in FIG. 5 is a section along D-D in FIG. 1 on an enlarged scale;

in FIG. 6 is a section along EE in FIG. 1 on an enlarged scale. The best embodiment of the invention

As shown in FIG. 1 and 2, the electromagnetic valve is located in the nozzle housing 1 and contains a magnetic circuit 2 with a winding 3 and an armature 4 mounted on the pusher 5. The magnetic circuit 2 is pressed through the insulator 17 in the sleeve 18, pressed by the nut 19 through the adjusting washer 15 to the housing 1. In the magnetic circuit 2, a cap 16 of non-magnetic material is mounted on its axis, protruding from this magnetic circuit 2 to a distance N (Fig. 2). The voltage on the winding 3 is supplied through the contacts 20 passing through the holes in the insulator 17 (not shown) and filled with plastic in the manufacture of the pads 21.

The pusher 5 is installed in the hole 7 of the housing 1 with the possibility of axial movement and under the action of the spring 8 with the adjusting washer 9 presses the locking element 10 through the spacer 11 to its seat, blocking the hole 12.

As shown in more detail in FIG. 3, the anchor 4 is mounted on the pusher 5 by means of an elastic disk 13, made integral with the pusher 5, and a deformable ring 6. The outer diameter of the thrust ring 6 is equal to the diameter of the elastic disk 13, and the inner diameter is 1, 3 - 2 diameters of the pusher 5. The stiffness of the thrust ring 6 is 2 to 5 times higher than the stiffness of the elastic disk 13. The elastic disk 13 and the deformable ring 6 are pressed against each other and fastened to the armature 4 on the periphery, in particular, crimped. A bore is made in the armature 4, so that a damping cavity 14 is formed between the elastic disk 13 and the armature 4, and the deformable ring 6, which acts as a stop, is located on the other side of the damping cavity 14 with respect to the elastic disk 13 and limits the deformation of the elastic disk 13 towards the closed side magnetic circuit. In this case, the damping cavity 14 has the shape of a ring, the annular gap S on the inner diameter d of which forms the output section of the damping cavity. The ratio of the outer diameter D of the cavity 14 to the specified inner diameter d lies in the range from 1, 8 to 3, and the axial size of the slit S of the output section of the damping cavity 14 is 0.5 to 1.5 of the working stroke M of the pusher 5.

The stroke M of the pusher 5 is defined as the distance from the surface of the armature 4 facing the magnetic core 2 to the cap 16 in the pressed position of the locking element 10 to its seat. This stroke M can be controlled by selecting the thickness of the adjusting washer 15 (Fig. 2), which determines the position of the magnetic circuit 2 relative to the housing 1. The minimum clearance between the armature 4 and the magnetic circuit 2 is determined by the protrusion N of the specified cap 16.

As shown in FIG. 2, the pusher 5 has an axial hole 22 and grooves 23 for the passage of fuel consumed for controlling the nozzle to the magnetic circuit 2 for cooling it, and then into the cavity 24 of the electromagnet. The hole 25 and the grooves 26 (Fig. 1) connect the specified cavity 24 with the drain fitting 27. The sealing ring 28 prevents the passage of fuel flowing from the hole 12 immediately to the drain fitting 27, if the pressure drop does not exceed the permissible. Sealing of the cavity 24 is carried out by a rubber sealing ring 29.

The solenoid valve described above controls the operation of an electro-hydraulic nozzle, for example, a diesel internal combustion engine, comprising a spray gun 30 connected to a hollow body 1, in which three needles 31 are installed, covering the spray holes 32. The upper ends of the needles 31 in the closed state coincide with the end of the spray gun 30. The needles 31 are kept from turning either by those needles 31 that are pressed against the saddle, or due to friction between the needle 31 and the pusher 33 interacting with it. A bore 34 is made in the housing 1 (Fig. 4), which determines the maximum value h of raising the needles 31. To maintain stability in a compressed state, thickeners 35 are made on the needles 31, each of which has flat platforms 36 (Fig. 5) for mutual support of the needles 31 against each other and a cylindrical support 37 on the inner diameter of the spray gun 30. Corresponding to the number of needles 31 (Fig. 1) in the housing 1, there are 3 relatively thin pushers 33 made of a spring wire with about 2500 MPa, which interact with the needles 31. The direction of the said thin pushers 33 in the body e 1 to maintain their stability in the compressed state is carried out on most of their surface in the openings 38 (FIG. 6) housing 1.

Each pusher 33 (Fig. 1) is affected by a locking multiplier 39, the upper part of which is under the influence of the fuel pressure in the hydraulic control chamber 40 (Fig. 2). The multiplier 39 in the lower part has a thrust shoulder 41, which provides preliminary compression of the pusher 33, because the distance between the upper end of the needle 31 in its closed position and the lower end of the multiplier 39, pressed by the shoulder 41 to the end of the multiplier sleeve 42 (i.e. in the upper position), is less than the length of the pusher 33 in the free state, which ensures that the needle 31 is pressed against the saddle when lack of pressure in the system. The magnitude of this compression is about 0.2 mm, which eliminates the influence of the difference in the coefficients of thermal expansion of the parts and reduces the requirements for the accuracy of their manufacture. The holes 38 (Fig. 1) for supporting the pusher along the axis of action of the forces of the needle 31 and the multiplier 39 are made inclined with great accuracy on a wire EDM machine.

Fuel into the hydraulic control chamber 40 (Fig. 2) enters through the inlet fitting 43 (Fig. 1), the holes in the housing 1, the tubular pin 44 and the throttle hole 45 (Fig. 2) and can be ejected from it through the hole 12, by opening which is controlled by a solenoid valve.

The solenoid valve in the hydraulic fuel injector operates as follows.

When the electromagnet is turned on, the armature 4 (Fig. 2) is attracted to the magnetic circuit 2, compressing the spring 8 through the thrust ring 6 and releasing the locking element 10. In this case, the force of impact of the armature 4 on the end face of the cap 16 is damped by displacing the liquid from the gap between the armature 4 and the magnetic circuit 2, reducing the magnitude of the rebound during the collision of the armature 4 with the end face of the cap 16, and a significant area of the colliding surfaces provides the necessary life of the nozzle.

The release of the locking element 10 leads to a drop in pressure in the hydraulic control chamber 40, and the multiplier 39 under the action of the elastic forces of the pusher 33 (Fig. 1) and the pressure of the fuel acting on the differential platform of the needle 31 rises to the contact of the shoulder 41 with the multiplier sleeve 42. In this case the needle 31, rising by the value of h (Fig. 4), determined by the depth of the bore 34, all the way to its bottom, opens the spray holes 32 (Fig. 1) for fuel injection through the inlet fitting 43 and the channel in the housing 1 into the spray cavity thirty.

When the electromagnet is turned off, the anchor 4 (Fig. 2), under the action of the spring 8, breaks away from the magnetic circuit 2 through the thrust ring 6 and, moving together with the pusher 5 and the spacer 11, puts the locking element 10 into the valve seat. In this case, due to the elastic connection of the armature 4 and the thrust ring 6 with the pusher 5, the impact force of the locking element 10 on the saddle decreases approximately by a factor of many times, how many times the mass of the pusher 5 is less than the total mass moving from the mass of the pusher 5, the armature 4 and the thrust ring 6. At the same time, the stress decreases by the collision of the locking element 10 and its seat, reducing their wear, and the energy of the rebound of the locking element 10 is reduced by the same amount.

At the moment of the collision of the locking element 10 with the saddle, the armature 4 together with the thrust ring 6 continues to move by inertia towards the opening of the magnetic circuit, deforming the elastic disk 13. At the same time, fuel is displaced from the cavity 14 (Fig. 3), damping most of the kinetic energy of the armature 4 and the thrust ring 6 and reducing the amount of deformation of the elastic disk 13 and, as a consequence, the value of the stored strain energy. The deformation of the elastic disk 13 also leads to the formation of a cavity between the elastic disk 13 and the thrust ring 6, which under the influence of the resulting vacuum is filled with fuel, and when the elastic disk 13 is straightened to its original position, the fuel is displaced from this cavity, providing a smooth fit of the thrust ring 6. the force of their impact is less than the force of the spring 8, which eliminates the undesirable separation of the locking element 10 (Fig. 2) from the saddle.

When the locking element 10 is seated in the saddle, the fuel entering through the inlet fitting 43 (Fig. 1), the channel in the housing 1, the tubular pin 44 and the throttle bore 45 (Fig. 2) into the hydraulic control chamber 40 increases the pressure in it to the operating value. The multiplier 39 under pressure in the hydraulic control chamber 40 moves downward, acting on the plunger 33, which, in turn, moves the needle 31 (Fig. 1) before landing it in the seat made in the atomizer 30, blocking the fuel supply.

This design allows you to drastically reduce the axial dimensions of the structure, which is especially important when used in an injector with three independently controlled needles 31. In addition, the problem of the rebound of the locking element 10 when it collides with the seat is solved in a more technological way, since the locking element 10 is additionally pressed by the anchor 4 deforming the elastic disk 13 of the pusher 5, excluding the undesirable opening of the locking element 10 during the return movement of the armature 4 due to the presence of two damping cavities, about on of which is formed between the armature 13 and the resilient disk pusher 5, while the other is formed during deformation of the elastic disc 13 between it and the thrust ring 6.

A decrease in the collision force of the locking element 10 against the saddle will allow, without increasing the stresses arising at the same time, on the saddle and the locking element 10 to reduce the diameter of the locking element 10 and, as a result, using the same electromagnet, control a significantly higher fuel pressure.

Claims

CLAIM

1. An electromagnetic valve for a hydraulic fuel injector containing an electromagnet, a pusher (5), spring-loaded in the direction of opening the magnetic circuit and connected with the locking element (10), the armature of the electromagnet (4) mounted on the pusher (5) with the possibility of axial movement relative to the pusher (5) in the direction of opening of the magnetic circuit and having an emphasis in the direction of closure, and the movement of the armature (4) in the direction of opening of the magnetic circuit is limited by an elastic element, characterized in that the elastic element is made in the form of an elastic a disk (13) combined with a pusher (5) and rigidly connected by its peripheral part to an anchor (4) with the formation of a damping cavity (14) between the end face of the elastic disk (13) and the anchor (4), and the emphasis is an elastically deformable ring ( 6), fixed on the periphery in the anchor (4) on the other side of the damping cavity relative to the elastic disk (13).

2. An electromagnetic valve according to claim 1, characterized in that the damping cavity (14) has the shape of a ring, an annular gap (S) on the inner diameter (d) of which forms an outlet section of the damping cavity.

3. The electromagnetic valve according to claim 2, characterized in that the axial size of the slit (S) of the output section of the damping cavity (14) is 0.5 - 1.5 of the stroke (M) of the pusher (5), and the ratio of the outer diameter (D) ) of the damping cavity (14) to the inner diameter (d) is 1.8 - 3.

4. An electromagnetic valve according to claim 1, characterized in that the stiffness of the thrust ring (6) is 2 to 5 times greater than the stiffness of the elastic disk (13).

5. The electromagnetic valve according to any one of paragraphs 1 to 4, characterized in that the outer diameter of the thrust ring (6) is equal to the diameter of the elastic disk (13), and its inner diameter is 1.3 to 2 diameters of the pusher (5).