DE102012201413A1 - Magnetic valve i.e. fast-switching magnetic valve, for common-rail injector for injecting fuel into combustion chamber of internal combustion engine, has damping chamber engaged with locating surface for creating excess stroke impact - Google Patents

Abstract

The valve has a magnet component (1) including an electromagnet (2) and a multi-part anchor (3) that cooperates with the electromagnet. The anchor comprises an anchor plate (6) that is axially pre-stressed in a direction of a valve seat (5) by force of a spring (4). A damper (7) attenuates stroke movement of the plate toward the seat and comprises a stroke-movable sleeve (9) that is indirectly supported at the plate by another spring (8) for limiting a fluid-filled damping chamber (10). The chamber is brought in engagement with a locating surface (11) for creating excess stroke impact.

Description

The invention relates to a solenoid valve for a fuel injector, in particular a common rail injector, for injecting fuel into the combustion chamber of an internal combustion engine with the features of the preamble of claim 1.

State of the art

The use of solenoid valves in fuel injectors to control the injection process is known. About the switching position of the solenoid valve, the control pressure in a control chamber can be influenced, which acts on a nozzle needle of the fuel injector in the direction of a nozzle needle seat. If the control pressure is lowered by opening the solenoid valve, the nozzle needle can perform a lifting movement, via which at least one injection opening is released. To end the injection process, the control pressure in the control chamber is increased by closing the solenoid valve and simultaneously refilling the control chamber with fuel, so that the nozzle needle is placed back into the nozzle needle seat.

For the realization of multiple injections fast switching valves are usually preferred. However, fast-switching valves often have the disadvantage that the moving components strike at high speed on stop-forming further components. It comes to so-called bouncers, especially closing bouncers, which should be avoided. Because on the one hand, the wear on the respective components is increased, on the other hand, the function of the injector can be impaired in a significant way.

In the DE 10 2007 060 396 A1 Therefore, a device for preventing bouncing bouncers for a solenoid valve is proposed, which comprises a formed between an armature and a stopper nip, the task of which is to decelerate the movement of the armature in the direction of the stop. The stop is preferably formed on a valve needle, which forms a two-mass oscillator with the anchor. This means that the valve needle form a first and the armature a second mass, which are displaceable relative to each other and thus can oscillate against each other. This has the consequence that after resetting the valve needle in the valve seat, the armature can continue its movement in the direction of the valve seat until it is braked over the nip.

In the DE 10 2009 045 623 A1 Furthermore, a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine with a solenoid valve of the aforementioned type is proposed, which have a minimized closing bounce and beyond should be simple and easy to assemble. The nip is for this purpose formed directly between the armature and valve needle. When closing the solenoid valve acts on the valve seat only the pulse of the valve needle, while the armature swings in the direction of an overstroke. Thus, the impact momentum and the maximum force are reduced. In order to be able to implement short injection processes, it is further proposed that the overstroke stop is formed directly by the valve needle and limits the swinging of the armature, so that the armature can be returned to its starting position within the shortest possible time.

Based on the above-mentioned prior art, the present invention has for its object to provide a fast-switching solenoid valve with a damping device to prevent bouncing bouncers, which allows a reduction of the spray intervals between two injections and thus favors multiple injections. At the same time, the solenoid valve should be easy to install.

To solve the problem, a solenoid valve for a fuel injector with the features of claim 1 is proposed. Advantageous embodiments of the invention are specified in the subclaims.

Disclosure of the invention

The proposed solenoid valve comprises a magnet assembly having an electromagnet and a cooperating with the electromagnet, multi-part armature assembly, wherein the armature assembly a hubbewegliche and by the spring force of a spring in the direction of a valve seat axially biased anchor plate and a damping device for damping the lifting movement of the armature plate in the direction of the valve seat includes. According to the invention, the damping device has a liftable sleeve indirectly supported by a spring on the armature plate for limiting a fluid-filled damper space, which can be brought into contact with a stop surface to form an overstroke stop. This means that the lifting movement of the sleeve is limited by the stop surface, but the spring, by means of which the sleeve is supported on the anchor plate, initially allows a continuation of the armature plate movement in the direction of the valve seat. Due to the relative movement of the armature plate relative to the sleeve, a pressure builds up in the intermediate fluid-filled damper chamber, which on the one hand slows down the armature plate in its movement, on the other holds the sleeve in abutment with the stop surface. In plant of the sleeve with the stop surface is in the Damper space included existing fluid and forms an overstroke stop, which limits the overstroke of the anchor plate relative to the sleeve. Depending on the design of the damper chamber short reset times or return paths of the armature plate and thus minimal distances between two injections can be realized in this way. Furthermore, the assembly costs can be reduced, since complex adjustment processes for adjusting the overtravel omitted.

According to a preferred embodiment of the invention, the stop surface is formed on a liftable anchor bolt, which passes through the anchor plate. The anchor plate is displaceable relative to the anchor bolt and is guided over the anchor bolt at least over part of its path, in particular in the damping phase. Due to the design of the stop surface on the anchor bolt, the arrangement of a separate stop element is unnecessary. Furthermore, a movable stop is formed in this way, since the anchor bolt - at least temporarily - follows the movement of the anchor plate.

Furthermore, the anchor bolt can be used as a force transmission member which acts on a valve closing element in such a manner that the valve closing element is held in the closed position of the solenoid valve in contact with the valve seat.

In order to include the fluid in the damping chamber, it is further proposed that a cooperating with the stop surface sealing edge is formed on the sleeve. About the sealing edge of the damping chamber is sealed against a surrounding the sleeve pressure chamber. To increase the sealing effect may also be provided that the sealing edge is formed in the form of a biting edge. This means that the preferably radially extending abutment surface is opposite a sealing surface of the sleeve extending obliquely thereto and the sealing edge of the sleeve is formed by surfaces lying at an acute angle to one another.

According to one embodiment of the invention, the fluid-filled damper chamber is relieved via a damper throttle. The degree of damping can be adjusted via the flow cross section of the damper throttle. If the degree of damping is too high, so that possibly the armature plate rebounds on the fluid enclosed in the damper chamber, the throttle cross-section can be increased, whereby the degree of damping decreases. With decreasing degree of damping, however, the return path of the anchor plate becomes longer, which in turn has a negative effect on the spray intervals. The damper throttle is preferably formed in the sleeve, which limits the damper space at least in the radial direction. For this purpose, a radially or obliquely extending bore may be provided in the sleeve, which connects the damper chamber with the pressure chamber surrounding the sleeve.

Further preferably, it is provided that the fluid-filled damper space is limited in the axial direction on the one hand by the anchor plate and on the other hand by the sleeve. The respectively provided on the anchor plate and on the sleeve surfaces for axially limiting the damper chamber serve as hydraulic active surfaces, which at least temporarily cause a hydraulic coupling of the sleeve with the anchor plate at a movement of the armature plate in the direction of the electromagnet, so that the sleeve movement the anchor plate follows. In this case, the sleeve lifts off from the preferably formed on the anchor bolt stop surface and opens the damper chamber. Thereafter, the anchor plate stops its lifting motion without braking, so that a rapid opening of the solenoid valve is ensured.

According to a preferred embodiment, the sleeve has a radially inner annular surface for axially limiting the fluid-filled damper space. The radially inner annular surface may be formed by a collar of the sleeve, which extends radially inward. As the annular surface axially delimits the damper space, during the damping phase, i. with increasing pressure in the damper chamber, via the annular surface causes a higher sealing force against the abutment surface formed on the anchor bolt.

Alternatively or additionally, it may be provided that the sleeve has a radially outer annular surface for supporting the spring also supported on the anchor plate. The radially outer annular surface is preferably also formed on a collar of the sleeve, which extends in this case, however, radially outward.

Advantageously, the armature plate is acted upon in the direction of the electromagnet by the spring force of a further spring. The other spring serves to return the anchor plate. The higher the spring force of the other spring, the faster the anchor plate is returned to its original position. The spring force of the other spring must be added to the spring force of the opposing acting and the armature plate acting in the closing direction spring so that it is interpreted accordingly stronger. Preferably, the spring force of the further spring, which serves to restore the anchor plate, greater than the spring force of the likewise supported on the anchor plate spring selected, which serves primarily the provision of the sleeve against the preferably formed on the anchor bolt stop surface. This is possible because the mass of the sleeve is significantly lower.

Preferably, a cooperating with the valve seat separate valve closing element is provided, which is further preferably formed spherical and / or durable on the armature assembly in contact with the valve seat. For example, the anchor bolt of the armature assembly may hold the valve closure member in abutment with the valve seat. If the valve closing element is spherical, the valve seat preferably has a conical shape, so that an optimum sealing seat is achieved. For this purpose, a dome-shaped bearing surface can be formed on the anchor bolt or a dome-shaped receiving element can be arranged, which or which is adapted to the spherical shape of the valve closing element.

The valve closing element is furthermore preferably accommodated in a valve space, which is delimited by a sleeve-shaped component which partially encloses the armature arrangement. The sleeve-shaped component serves to guide the anchor assembly, in particular the leadership of the anchor bolt of the armature assembly.

Since the advantages of a solenoid valve according to the invention come into play, in particular when used in a fuel injector, a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine with such a solenoid valve is also claimed.

Preferred embodiments of the invention are explained below with reference to the drawings. These show:

1 a schematic longitudinal section through a first inventive solenoid valve,

2 a section from 1 in the region of the damping device of the solenoid valve according to the invention,

3 a schematic longitudinal section through a second inventive solenoid valve and

4a E each a schematic longitudinal section, which the solenoid valve of 3 in a certain functional position shows.

Detailed description of the drawings

A first preferred embodiment of a solenoid valve according to the invention is in the 1 and 2 shown. It includes a magnet assembly 1 with an electromagnet 2 and one with the electromagnet 2 cooperating armature arrangement 3 , The anchor assembly is formed in several parts and includes an anchor plate 6 , one through the anchor plate 6 guided anchor bolts 12 and a spring 4 whose spring force is the anchor plate 6 and the anchor bolt 12 in the direction of a valve seat 5 applied. The feather 4 can therefore also be referred to as anchor return spring. The anchor bolt 12 has at its valve seat near the end of a dome-shaped receiving element 21 in the form of a spherical valve closing element 18 is adjusted. About the anchor bolt 12 or the dome-shaped receiving element arranged thereon 21 can the spherical valve closing element 18 in contact with the valve seat 5 be brought or held to close the solenoid valve. The closing force is from the spring 4 provided which directly or indirectly the anchor assembly 3 in the direction of the valve seat 5 applied. For adjusting the spring force of the spring 4 is present between the anchor plate 6 and the spring 4 a dial 22 arranged.

The spherical valve closing element 18 is in a valve room 20 taken, which of a sleeve-shaped component 19 is enclosed. The volume of the valve chamber 20 is reduced in this way. The sleeve-shaped component 19 is from the anchor bolt 12 the anchor arrangement 3 permeated, so that the dome-shaped receiving element arranged thereon 21 in contact with the valve closing element 18 arrives. The sleeve-shaped component 19 has at least one hole 23 for pressure relief and / or pressurization of the valve chamber 20 on. Furthermore, the valve chamber 20 in the open position of the valve via a drainage channel 24 and a drain throttle formed therein 25 with a control room (not shown) connectable. In the closed position of the valve, this connection is made via the valve seat 5 fitting spherical valve closing element 18 separated.

The anchor arrangement 3 in the 1 and 2 shown solenoid valve further comprises a damping device 7 in the form of a sleeve 9 which a hollow cylindrical approach of the anchor plate 6 surrounds and over a spring 8th indirectly on the anchor plate 6 is supported. The sleeve 9 has a radially inwardly extending collar 27 with a first ring surface 15 on which together with the anchor plate 6 a damper room 10 encloses. The damper room 10 at the same time serves as a hydraulic coupler volume, which when driving the valve entrainment of the sleeve 9 by the movement of the anchor bolt 12 causes. Because in the starting position, in which the sleeve 9 about the spring force of the spring 8th is held, lies the sleeve 9 with a sealing edge designed as a biting edge 13 at one on the anchor bolt 12 provided stop surface 11 at. Thus, the fluid filled damper space 10 opposite one the sleeve 9 surrounding pressure chamber 26 sealed. About that in the damper room 10 trapped fluid is an attenuation of the movement of the anchor plate 6 effected. The feather 8th over which the sleeve 9 indirectly on the anchor plate 6 supported is located on a radially outer annular surface 16 a radially outwardly extending collar 27 at.

For adjusting the damping effect of the damping device 7 has the sleeve 9 an oblique bore having a damper throttle formed therein 14 on. In addition, the bore itself can also be the damper throttle 14 form. The adjustment of the degree of damping via the flow cross section of the damper throttle 14 , If the degree of damping should be increased, the flow cross-section should be reduced. As far as a reduction of the degree of damping is desired, the flow cross-section of the damper throttle 14 to enlarge.

An alternative embodiment of the solenoid valve according to the invention is in the 3 and 4a -E shown, using the 4a See below, for example, the operation of the damping device 7 a solenoid valve according to the invention will be explained.

Like from the 3 the alternative embodiment differs from that of FIG 1 and 2 primarily by having one more spring 17 is provided, which is the anchor plate 6 in the direction of the electromagnet 2 applied. The feather 17 accelerates the return of the anchor plate 6 in its starting position and thus leads to a faster completion of the injection process. The feather 17 this is on the one hand to the anchor plate 6 and on the other hand on the sleeve-shaped component 19 supported, which the valve space 20 surrounds.

Unless there is a spring 17 for returning the anchor plate 6 is provided (as in the embodiment of the 1 ), the return of the anchor plate takes place 6 via the magnetic force of the magnet assembly 1 with the beginning of the next injection process.

The operation will now be exemplified by the 4a -E explained.

At rest ( 4a ) becomes the anchor assembly 3 about the spring force of the spring 4 in contact with the valve seat 5 held. The spring force acting as the closing force of the spring 4 is doing over the anchor bolt 12 the anchor arrangement 3 and the dome-shaped receiving element 21 on the spherical valve closing element 18 transfer. The sleeve 9 the damping device 7 this is due to the valve pin 12 trained stop surface 11 so that the damping room 10 opposite the pressure chamber 26 is sealed.

Will the electromagnet 2 energized to open the valve (see 4b , Opening phase) becomes the armature arrangement 3 or the anchor plate 6 by the magnetic force F _M against the spring force F _{A of} the armature spring 4 in the direction of the electromagnet 2 emotional. The anchor bolt 12 is through the valve closing element 18 applied hydraulic pressure force also in the direction of the electromagnet 2 emotional. By the sleeve 9 at the stop surface 11 of the anchor bolt 12 is supported, the sleeve is 9 from the anchor bolt 12 carried. At this stage, there is no damping of the movement of the anchor plate 6 causes.

In the closing phase ( 4c ) is the energization of the electromagnet 2 stopped and the magnetic force degraded, leaving the spring force of the armature spring 4 the anchor arrangement 3 returns to the starting position. This will be the anchor plate 6 and the anchor bolt 12 initially moved together in the direction of the valve seat until the valve closing element 18 in contact with the valve seat 5 arrives. The movement of the anchor bolt 12 is over. Now the damping phase begins.

In the damping phase ( 4d ) is the movement of the anchor plate 6 in the direction of the valve seat 5 initially continued, causing a pressure increase in the fluid-filled damper space 10 entails. The pressure increase causes the sleeve 9 against the stop surface 11 is pressed, leaving the sleeve 9 the damper room 10 opposite the pressure chamber 26 seals. Furthermore, over the against the stop surface 11 pressing sleeve 9 a bouncing of the anchor bolt 12 prevented. That in the damper room 10 trapped fluid, only through the damper throttle 14 It also causes the movement of the anchor plate 6 is slowed down. That in the damper room 10 enclosed fluid thus forms an overstroke stop.

The restraint phase is followed by the restoring phase ( 4e ), in which the armature assembly 3 is returned to its original position to allow a new injection process. This is the anchor plate 6 about the spring force of the spring 17 in the direction of the electromagnet 2 moved back. Due to the hydraulic coupling via the in the damper chamber 10 enclosed fluid follows the sleeve 9 the movement of the anchor plate 6 and lifts it from the anchor bolt 12 trained stop surface 11 from. The damper room 10 opens, so that the provision is unrestrained. Has the anchor plate reached its upper stroke stop causes the spring 8th the provision of the sleeve 9 against the stop surface 11 ,

Is an extra spring 17 to assist the return movement of the anchor plate 6 Not provided (embodiment of the 1 and 2 ), is the return time of the armature assembly 3 essentially by the set degree of damping and the spring force of the spring 8th influenced. The lifting and thus deactivating the damping device 7 takes place here delayed, namely with the initiation of a new opening phase instead. The switched magnetic force F _M causes the sleeve 9 from the stop surface 11 lifts and the damping device 7 is deactivated, causing a quick return of the anchor plate 6 entails. The return of the anchor plate 6 at the beginning of the opening phase has little effect on the function, since the return path due to the damping device 7 is very low. In addition, the rapid increase in magnetic force and the magnitude of the magnetic force cause a quick return of the anchor plate 6 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007060396 A1 [0004]
• DE 102009045623 A1 [0005]

Claims (10)

Solenoid valve for a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, comprising a magnet assembly ( 1 ) with an electromagnet ( 2 ) and one with the electromagnet ( 2 ) cooperating, multipart armature arrangement ( 3 ), wherein the armature arrangement ( 3 ) a liftable and by means of the spring force of a spring ( 4 ) in the direction of a valve seat ( 5 ) axially prestressed anchor plate ( 6 ) and a damping device ( 7 ) for damping the lifting movement of the anchor plate ( 6 ) in the direction of the valve seat ( 5 ), characterized in that the damping device ( 7 ) indirectly via a spring ( 8th ) on the anchor plate ( 6 ) supported, liftable sleeve ( 9 ) for limiting a fluid-filled damper space ( 10 ), which for forming an overstroke stop in contact with a stop surface ( 11 ) can be brought. Solenoid valve according to claim 1, characterized in that the stop surface ( 11 ) on a liftable anchor bolt ( 12 ) is formed, which the anchor plate ( 6 ) interspersed. Solenoid valve according to claim 1 or 2, characterized in that on the sleeve ( 9 ) one with the stop surface ( 11 ) cooperating sealing edge ( 13 ), preferably in the form of a biting edge. Solenoid valve according to one of the preceding claims, characterized in that the fluid-filled damper space ( 10 ) via a damper throttle ( 14 ) is relieved, wherein the damper throttle ( 14 ) preferably in the sleeve ( 9 ) is trained. Solenoid valve according to one of the preceding claims, characterized in that the fluid-filled damper space ( 10 ) in the axial direction on the one hand by the anchor plate ( 6 ) and on the other hand from the sleeve ( 9 ) is limited and upon movement of the anchor plate ( 6 ) in the direction of the electromagnet ( 2 ) at least temporarily a hydraulic coupling of the sleeve ( 9 ) with the anchor plate ( 6 ) causes. Solenoid valve according to one of the preceding claims, characterized in that the sleeve ( 9 ) a radially inner annular surface ( 15 ) for the axial limitation of the fluid-filled damper space ( 10 ) and / or a radially outer annular surface ( 16 ) to rest on the anchor plate ( 6 ) supported spring ( 8th ) having. Solenoid valve according to one of the preceding claims, characterized in that the armature plate ( 6 ) in the direction of the electromagnet ( 2 ) of the spring force of another spring ( 17 ) is applied, wherein preferably the spring force of the further spring ( 17 ) greater than the spring force of the anchor plate ( 6 ) supported spring ( 8th ) is selected. Solenoid valve according to one of the preceding claims, characterized in that one with the valve seat ( 5 ) cooperating separate valve closing element ( 18 ) is provided, which is preferably spherical and / or via the armature arrangement ( 3 ) in contact with the valve seat ( 5 ) is durable. Solenoid valve according to claim 8, characterized in that the valve closing element ( 18 ) in a valve chamber ( 20 ), which of a the armature arrangement ( 3 ) partially enclosing sleeve-shaped component ( 19 ) is limited. Fuel injector for injecting fuel into the combustion chamber of an internal combustion engine with a solenoid valve according to one of the preceding claims.

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