DE102012216534A1 - Pressure control valve for a fuel injection system - Google Patents

Abstract

The invention relates to a pressure regulating valve for a fuel injection system of an internal combustion engine, in particular a common rail injection system, comprising a valve housing (1) with a bore (2) in which a one-part or multi-part, axially displaceable valve closing element (3) and a spring ( 4) are received, the spring force of the spring (4) acting on the valve closing element (3) in the direction of a valve seat (5). According to the invention, the spring (4) is supported on the one hand on the valve closing element (3) and on the other hand on a spring plate (6) which is received in the bore (2) and adjustable in terms of its axial position within the bore (2). Means (7) for adjusting the axial position of the spring plate (6) are also provided. The invention also relates to a method for regulating pressure in a fuel injection system of an internal combustion engine, in particular a common rail injection system, in which a pressure regulating valve is used with a valve closing element (3) loaded by the spring force of a spring (4) in the direction of a valve seat (5) . According to the invention, the spring force of the spring is variably adjustable, the setting being effected by adjusting the axial position of a spring plate (6) on which the spring (4) is supported in the axial direction.

Description

The invention relates to a pressure regulating valve for a fuel injection system of an internal combustion engine having the features of the preamble of claim 1. Furthermore, the invention relates to a method for pressure control in a fuel injection system of an internal combustion engine having the features of the preamble of claim.

State of the art

From the DE 10 2007 062 176 A1 is a pressure control valve for controlling the pressure in a high-pressure fuel accumulator out, which is connectable to the high pressure fuel accumulator and having a valve piston which is acted upon against the pressure in the high pressure fuel accumulator by a spring force of a spring in the closed position. Furthermore, a first controllable magnetic device is provided, whose force counteracts the spring force acting on the valve piston, and a second magnetic device whose force supports the spring force. In the known pressure control valve is therefore a "modified" normally closed pressure control valve, wherein the closing force via a spring and in addition a second magnetic device is effected. As with conventional normally closed pressure control valves, a safety function is to be realized by the spring force, which ensures an emergency operation functionality in the event of a fault. However, a weaker spring can be used by the use of a second magnetic device supporting the spring. The spring force of the spring is used to set the mechanical opening pressure of the valve, which is preferably in the middle pressure range of the system. By the force of the additional magnetic device, which adds to the spring force, the opening pressure can be controlled to a range between the mechanical opening pressure and a maximum allowable system pressure, so that when the maximum allowable system pressure in the high-pressure fuel storage tank is exceeded, the valve opens and a pressure limit is ensured. By an intelligent power control by means of a control device also a steady pressure increase / decrease should be realized. The weaker spring ensures that the system pressure remains within the operating range in the event of a power supply error.

In addition, normally open pressure control valves for pressure control in high-pressure reservoirs of an internal combustion engine are known, which have a closing element of the pressure control valve in the opening direction applied at standstill of the internal combustion engine, so that in the absence of energization, the connection is released from the high-pressure accumulator into a low pressure region. Such a normally open pressure control valve is for example from the DE 10 2004 002 964 A1 out. The closing of the valve closing element is effected here by means of a magnetic actuator which comprises a coil and an armature plate.

Such normally open pressure control valves regularly have the disadvantage that increases when opening the air gap between the armature plate and the coil, resulting in a reduced magnetic force result. This can mean that the valve can only be actively closed. Another disadvantage is seen in the relatively high moving masses and the associated relatively low natural frequency. In addition, such a pressure regulating valve has a sensitive behavior to low-pressure disturbances, since the actuator chamber and the valve chamber are usually not pressure-balanced.

Based on the above-mentioned prior art, the present invention has for its object to provide a pressure control valve having an increasing Aktorkraft- / valve lift characteristic. Further, a pressure control valve with reduced moving masses is to be provided, which is also less sensitive to low-pressure noise.

To solve the problem, the pressure regulating valve is proposed with the features of claim 1. Advantageous developments of the invention are specified in the dependent claims. Further, a method for pressure control in a fuel injection system of an internal combustion engine is proposed to achieve the object.

Disclosure of the invention

The proposed pressure control valve for a fuel injection system of an internal combustion engine, in particular a common rail injection system, comprises a valve housing having a bore in which a one or more parts trained, axially displaceable valve closure member and a spring are accommodated. The spring force of the spring acts on the valve closing element in the direction of a valve seat. According to the invention, the spring is supported on the one hand on the valve closing element and on the other hand on a spring plate, which is received in the bore and adjustable in terms of its axial position within the bore. Furthermore, according to the invention means for adjusting the axial position of the spring plate are provided.

The proposed pressure control valve is based on the principle of a passive pressure-holding valve, in which causes the closing force by means of a spring becomes. As long as the force acting on the valve closing element hydraulic force is smaller than the set spring force, the pressure-maintaining valve remains closed. The same applies to the proposed pressure control valve according to the invention. The opening force is adjusted by the spring force of the spring, which in this case is variable, in order to be able to further effect a pressure control. The adjustment of the spring force takes place via an adjustment of the axial position of a spring plate on which the spring is supported.

The use of a spring for generating a force acting in the closing direction of the valve pressure force has the advantage that the moving masses can be kept low. The preferred use of a stiff spring also leads to a high natural frequency. Furthermore, it is already ensured by the spring force of the spring alone that the valve closing element is placed back in the valve seat when the target pressure is reached. Because with increasing opening stroke of the valve closing element and the spring force of the spring increases.

According to a preferred embodiment of the invention, electrical, electromagnetic and / or mechanical means for adjusting the axial position of the spring plate are provided. By means of such means, a defined change in position of the spring plate and thus a precise adjustment of the spring force can be made. Preferably, the means for adjusting the axial position of the spring plate comprise an electromagnet and / or a threaded spindle. For example, a magnetic actuator can be provided, which causes an axial adjustment of the spring plate within the bore directly or indirectly. Alternatively or additionally, a rotary drive can be provided, which cooperates with a threaded spindle as a mechanical adjusting means. In this case, the spring plate may be formed as a spindle nut, so that the rotation of the threaded spindle is directly effected an axial displacement of the spring plate. In addition, a variety of other adjustment means for axial adjustment of the spring plate can be used, which can not be exhaustively listed here.

Furthermore, it is proposed that the valve closing element has a cooperating with the valve seat, spherically shaped sealing surface. In particular, in combination with a conical valve seat, a good sealing effect is achieved in this way, since an annular contact area is formed. Furthermore, a self-centering of the valve closing element can be effected via the spherically shaped sealing surface.

As a further development measure, it is proposed that the valve closing element is designed in several parts and comprises a spherical sealing body and a valve piston. The spring is preferably supported in this case on the valve piston, which thus serves as a force transmission member. The spring force transmitted indirectly via the valve piston to the sealing body causes the sealing body to be returned to the valve seat or held in sealing contact with the valve seat. To guide the spherical sealing body preferably has the valve piston in the region of the sealing body facing end face a spherical recess. The spherically shaped recess preferably has a diameter which corresponds to the diameter of the spherical sealing body or is chosen larger. A larger diameter promotes self-centering of the spherical sealing body with respect to the valve seat.

About the stroke of the valve closing element and / or the adjustment of the axial position of the spring plate, the axial distance between the valve closing element and the spring plate is variable, which has an influence on the spring force of the spring supported thereon. While the opening stroke of the valve closing element causes a passive increase in the spring force, so that a sufficient closing force is ensured, by means of an active adjustment of the axial position of the spring plate, a pressure control can be realized.

Advantageously, the valve housing has at least one radial bore for connecting the bore to a low-pressure region. The low-pressure region is advantageously connected via a return line to a fuel reservoir, in order to supply in particular an amount of fuel which has been diverted via the pressure regulating valve to the fuel reservoir.

Furthermore, a high-pressure fuel accumulator of a fuel injection system is claimed with a pressure control valve according to the invention for pressure control and / or pressure limiting in high-pressure fuel storage. The use of a pressure control valve according to the invention in a high-pressure fuel storage is therefore to be regarded as a preferred application. On the one hand, a defined opening pressure is adjustable via the spring of the pressure regulating valve, so that the pressure regulating valve opens when a maximum permissible pressure is exceeded and causes a pressure limitation. On the other hand, the valve allows pressure control, since the spring force of the spring is variably adjustable via an axial positional adjustment of the spring plate.

The pressure regulating valve according to the invention, which is particularly suitable for use in a high-pressure fuel accumulator, is further distinguished by the fact that expensive setting operations during assembly can be dispensed with. Because the fine adjustment can already be effected after installation via the means for adjusting the axial position of the spring plate on which the spring is supported. This means that the calibration can only be carried out after the pressure regulating valve has been installed in the internal combustion engine.

To achieve the object mentioned above, a method for pressure control in a fuel injection system, in particular a common rail injection system, further specified in which a pressure control valve is acted upon by the spring force of a spring in the direction of a valve seat valve closing element. According to the invention, the spring force of the spring is variably adjustable, wherein the adjustment is effected by adjusting the axial position of a spring plate, on which the spring is supported in the axial direction. The setting of the opening force is therefore effected via the adjustment of the spring force, which is therefore also variable. The proposed method thus allows both a pressure limit, as well as a pressure control in the fuel injection system.

Preferably, the adjustment of the axial position of the spring plate is effected by electrical, electromagnetic and / or mechanical means for adjustment. For example, the adjusting means may comprise an electromagnet and / or a threaded spindle. The electromagnet is furthermore preferably part of a magnetic actuator, by means of which the spring plate can be acted upon directly or indirectly. Alternatively, a piezoelectric actuator can also be used as adjusting means. Alternatively or additionally, the use of mechanical adjustment is possible. The abovementioned adjusting means are given by way of example only. A variety of other adjustment can be used, which can not be exhaustively listed here.

A preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings. This shows a schematic longitudinal section through an inventive pressure control valve.

Detailed description of the drawing

The schematic longitudinal section of the single figure is a valve housing 1 with an axially extending bore 2 to take in which a multi-part valve closing element 3 comprising a spherical sealing body 9 and a valve piston 10 , is received axially displaceable. The valve piston 10 is the spring force of a spring 4 charged, which also in the hole 2 is included, so this part of the hole 2 as a spring chamber 14 serves. The spring force of the spring 4 acts in the direction of a valve seat 5 which is substantially conical in shape and at one end of the bore 2 is trained. The valve piston 10 transfers the spring force to the spherical sealing body 9 , which thus via the valve piston 10 in contact with the valve seat 5 is held, as long as the at the spherical sealing body 9 applied system pressure is below the opening pressure of the pressure control valve. For optimum guidance of the spherical sealing body 9 to effect, the valve piston has 10 a spherical shaped recess 12 in the region of the sealing body 9 facing stand surface 11 on, wherein the diameter of the spherically shaped recess 12 essentially the diameter of the spherical sealing body 9 equivalent.

Due to the spherical shape of the sealing body 9 has the valve closing element 3 a spherical or spherically shaped sealing surface 8th on which sealing with the valve seat 5 interacts. Due to the spherical or spherically shaped sealing surface 8th of the sealing body 9 a seal over an annular contact surface is ensured.

If it rises on the sealing body 9 applied system pressure on the opening pressure of the pressure control valve, the sealing body lifts against the spring force of the spring 4 from the valve seat 5 off and the valve opens. About a radial bore 15 in the valve housing 1 is doing a connection of one in the hole 2 trained valve chamber 13 with a low pressure area 16 produced. This ensures that the system pressure does not exceed a given limit pressure. The specification of the limit pressure is set by adjusting the spring force of the spring 4 causes. For this purpose, the axial position of one in the bore 2 recorded spring plate 6 on which the spring 4 is supported, adjusted, so that the spring chamber 14 an enlargement or reduction learns. For adjusting the axial position of the spring plate 6 has the pressure regulating valve shown in the figure adjusting means 7 on that a threaded spindle 17 include the spring plate 6 interspersed. The spring plate 6 is provided with a counter-rotating thread and thus also serves as a spindle nut 18 , which upon rotation of the threaded spindle 17 undergoes an axial adjustment. To the rotation of the threaded spindle 17 To effect this is via a spindle bearing 19 rotatable in the valve body 1 stored. The rotation of the threaded spindle 17 can be effected via different drives or actuators (not shown), which are well known.

The invention is not limited to the illustrated pressure control valve, but also includes modifications, in particular the specific configuration of the means for adjusting the axial position of the spring plate 6 may concern and / or the combined embodiment of the valve closing element 3 , Furthermore, instead of the coil spring shown any other spring element can be used, which acts on the valve closing element in the direction of the valve seat with a compressive force.

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 102007062176 A1 [0002]
• DE 102004002964 A1 [0003]

Claims (8)

Pressure control valve for a fuel injection system of an internal combustion engine, in particular a common rail injection system, comprising a valve housing ( 1 ) with a bore ( 2 ), in which a one- or multi-part trained, axially displaceable valve closing element ( 3 ) and a spring ( 4 ), wherein the spring force of the spring ( 4 ) the valve closing element ( 3 ) in the direction of a valve seat ( 5 ), characterized in that the spring ( 4 ) on the one hand on the valve closing element ( 3 ) and on the other hand on a spring plate ( 6 ) supported in the bore ( 2 ) and in terms of its axial position within the bore ( 2 ) and that means ( 7 ) for adjusting the axial position of the spring plate ( 6 ) are provided. Pressure control valve according to claim 1, characterized in that electrical, electromagnetic and / or mechanical means ( 7 ) for adjusting the axial position of the spring plate ( 6 ) are provided, which preferably an electromagnet and / or a threaded spindle ( 17 ). Pressure control valve according to claim 1 or 2, characterized in that the valve closing element ( 3 ) one with the valve seat ( 5 ) cooperating, spherically shaped sealing surface ( 8th ) owns. Pressure control valve according to one of the preceding claims, characterized in that the valve closing element ( 3 ) is formed in several parts and a spherical sealing body ( 9 ) and a valve piston ( 10 ), wherein preferably the valve piston ( 10 ) in the region of the sealing body ( 9 ) facing end face ( 11 ) a spherical shaped recess ( 12 ) for guiding the spherical sealing body ( 9 ) owns. Pressure control valve according to one of the preceding claims, characterized in that the valve housing ( 1 ) at least one radial bore ( 15 ) for connecting the bore ( 2 ) with a low pressure area ( 16 ) owns. High-pressure fuel accumulator of a fuel injection system with a pressure control valve according to one of the preceding claims for pressure control and / or pressure limitation in the high-pressure fuel storage. Method for regulating pressure in a fuel injection system of an internal combustion engine, in particular a common-rail injection system, in which a pressure regulating valve with a spring force of a spring ( 4 ) in the direction of a valve seat ( 5 ) acted upon valve closing element ( 3 ) is used, characterized in that the spring force of the spring is variably adjustable and the adjustment by adjusting the axial position of a spring plate ( 6 ) is effected, on which the spring ( 4 ) is supported in the axial direction. A method according to claim 7, characterized in that the adjustment of the axial position of the spring plate ( 6 ) of electrical, electromagnetic and / or mechanical means ( 7 ) is effected for adjustment.

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