EP2647825A1 - High-pressure pump for a fuel injection system - Google Patents

Abstract

The pump (1) has a pump piston (20) reciprocating in a cylinder bore (18) of a pump cylinder (19) that is sealed by a pump cylinder head (23). A pumping workspace (13) is defined in the cylinder bore by the pump piston and the cylinder head. The pumping workspace is connected with a low pressure system (5) over an inlet valve (12). An electromagnetic coil (30) influences a magnetic component i.e. support body, of the inlet valve such that the opening movement and/or the closing movement of a valve element i.e. valve bolt (11), of the inlet valve are actively or passively controlled. The magnetic component acts as an armature.

Description

The present invention relates to a high-pressure pump for a fuel injection system of an internal combustion engine having a covered by a pump cylinder head and a cylinder bore having pump cylinder, wherein in the cylinder bore, a pump piston is translationally movable, of which a pump working space is formed in the cylinder bore together with the pump cylinder is connected via an inlet valve with a low pressure system, and wherein the opening movement and / or closing movement of a valve member of the inlet valve can be influenced by an actuator.

State of the art

Such a high-pressure pump for a fuel injection system is known from DE 10 2006 013 703 A1 known. This fuel injection system has an intake valve with which the amount of fuel to be metered to a pump working space of the high-pressure pump can be adjusted. This inlet valve is mechanically, hydraulically or electromagnetically adjusted and controls a flow connection between a low pressure system and pump working space of the high pressure pump. For example, in the case of an electromagnetic actuation of the inlet valve, the adjusting movement effected by an electromagnetic actuator is transmitted directly or indirectly via a spindle to the inlet valve. The adjusting device for the inlet valve designed in this way is structurally complex and accordingly prone to failure.

Alternatively, or in addition to the metering of the fuel by means of an electromagnetically actuated intake valve, it is known that the amount of fuel to be supplied to the pump working space by means of a metering unit adjust. Such a metering unit is to be installed as a separate component on the high-pressure pump of the fuel injection system.

The invention has for its object to provide a high-pressure pump for a fuel injection system, in which a reliable and accurate fuel metering is made possible in a pump working space of the high pressure pump with a simple structural design.

Disclosure of the invention Advantages of the invention

This object is achieved in that at least one electromagnetic coil is provided as an armature acting, magnetic component of the intake valve influencing. In this embodiment, only an electromagnetic coil is installed as an additional component in this general embodiment, which interacts directly without the interposition of, for example, a spindle with an existing magnetic component of the inlet valve. In this case, when the coil is energized, the movement of the component of the inlet valve acting as an armature is influenced. This influencing can be done so that an opening movement or closing movement of the intake valve is actively or passively controlled.

In a further embodiment of the invention, the component cooperates with the coil at least during a partial section of the opening movement and / or the closing movement of the inlet valve. The interaction is related to the subsection whose movement is to be influenced specifically. It is also provided in the context of the invention, several subsections, for example, during the opening movement and the closing movement by a corresponding arrangement of several coils to influence targeted.

In a further development of the invention, the component is a valve spring plate of the inlet valve. The valve spring retainer is attached to a valve member of the intake valve. On the valve spring plate, in turn, a valve spring is supported, which is connected to the valve member valve plate of the inlet valve in a Valve seat, which is incorporated in a valve housing or directly in the pump cylinder head moves. For this purpose, the valve spring is supported opposite to the valve spring plate on the valve housing or the pump cylinder head. The valve spring plate is made of a metallic, magnetically acting material and is therefore particularly suitable as cooperating with the electromagnetic coil armature. However, it is also conceivable within the scope of the invention for the component to be, for example, the valve member or the valve disk.

In a further embodiment of the invention, the coil is the component comprising embedded in a holding body as part of the inlet valve. However, the coil can also be used, for example, in an existing valve housing directly into a recessed into the valve housing recess. This configuration requires only a small additional construction costs. Finally, it is also conceivable to install the coil directly into the pump cylinder head.

In a further development of the invention, the holding body (or the valve housing or the pump cylinder head) is designed as a soft magnetic component. Such a soft magnetic component or material amplifies a magnetic field around the material permeability, which also determines the material conductivity of the corresponding material. Such a holding body is preferably embedded as an additional component in the pump cylinder head or a valve housing for the inlet valve.

In a further embodiment, the coil is separated fuel-tight relative to a fuel-filled valve spring plate space. This fuel-tight configuration makes it possible to arrange the coil directly adjacent to the armature and the holding body. In the context of the invention, it is also possible to arrange the coil in a sealed relative to the valve spring plate space space.

In a further development of the invention, the valve spring plate on a Stellausprägung. The Stellausprägung causes cooperating with the coil (or the coils) the ability to adjust the valve lift more accurate. It is possible in this embodiment and also in the embodiments described above to divide the coil into a plurality of separately activatable portions or to use more than one coil, which can be energized separately. This configuration allows, in particular together with the Stellausprägung the armature a differentiated control of the valve lift of the intake valve. Here are different Bestromungsmuster with divisions on the different sections of the coil or on the different coils conceivable. Likewise, different Stellausprägungsmuster, for example, by design of air gaps, introduction of soft magnetic material and the like are conceivable. This refinement further increases the control possibility of the fuel quantity to be supplied to the pump working chamber and thus the delivery quantity set by the high-pressure pump.

In a further embodiment of the invention, the coil is arranged in relation to the valve spring plate, that when the coil is energized, the opening movement of the inlet valve can be influenced. Alternatively, or for example by an additional coil, the closing movement of the intake valve can be reversely influenced in an energized coil. These embodiments further increase the adjustment possibilities of the intake valve.

In a further development of the invention, the actuator comprises the electromagnetic coil. In this case, it is the case in particular that the actuator, which is arranged externally in a conventional design, and the inlet valve is actuated by means of a spindle, is the sole coil. In the context of the invention, it is in principle also possible to install the coil as a supplement to an actuator controlling the inlet valve.

Further advantageous embodiments of the invention are described in the drawings, are described in more detail in the embodiments illustrated in the figures of the invention.

Brief description of the drawings

Figur 1

den prinzipiellen Aufbau eines Kraftstoffeinspritzsystems,

Figur 2

in einer Schnittdarstellung eine Detailansicht eines Einlassventils einer Hochdruckpumpe in einer ersten Ausführungsform,

Figur 3

in einer Schnittdarstellung eine Detailansicht eines Einlassventils einer Hochdruckpumpe in einer zweiten Ausführungsform, und

Figur 4a, 4b

jeweils in Diagrammform das Funktionsprinzip der Hochdruckpumpe bei unterschiedlicher Anordnung einer Spule in Bezug zu einem Anker.

Show it:

FIG. 1

the basic structure of a fuel injection system,

FIG. 2

in a sectional view a detail view of an inlet valve of a high-pressure pump in a first embodiment,

FIG. 3

in a sectional view of a detailed view of an inlet valve of a high-pressure pump in a second embodiment, and

Figure 4a, 4b

in each case in diagram form, the operating principle of the high pressure pump with different arrangement of a coil with respect to an anchor.

Embodiments of the invention

This in FIG. 1 illustrated fuel injection system for a particular diesel fuel-operated auto-ignition internal combustion engine is designed as a common-rail injection system and has a high-pressure pump 1. The high-pressure pump 1 delivers fuel supplied from a low-pressure system into a high-pressure accumulator 2, from which the fuel is injected by injectors 3 for injection into an internal combustion chamber of an internal combustion engine assigned to an injector 3 for combustion with simultaneously supplied combustion air.

The low-pressure system has a fuel tank 4, is taken from the fuel from a low-pressure pump 5 while passing through a filter 6, and is conveyed through a low pressure line 7 in a feed chamber 8 of the high-pressure pump 1. Downstream of the low-pressure pump 5, a return line 9 is connected to the low-pressure line 7, wherein in the return line 9, a pressure regulating valve 10 is turned on. The pressure control valve 10 limits the fuel pressure in the low pressure line 7 to a predetermined maximum pressure and directs regulated fuel back into the fuel tank 4.

The feed chamber 8 of the high-pressure pump 1 surrounds a valve member 11 formed as a valve member of an intake valve 12, which in a Pump working space 13 of the high-pressure pump 1 introduced amount of fuel determined. For this purpose, the inlet valve 12 is basically designed as a suction valve and has a preferably integrally formed with the valve pin 11 valve plate 14, which cooperates with a, for example, in a valve housing 15 incorporated valve seat 16. When in the FIG. 1 illustrated, open position of the intake valve 12, the feed chamber 8 is connected via a valve pin 11 surrounding the annular space 17 with the valve seat 16 and it flows from the low-pressure pump 5 funded fuel into the pump working space thirteenth

If the inlet valve 12 is closed and the valve disk 14 moves to rest in the valve seat 16, is simultaneously moved by a in a cylinder bore 18 of a pump cylinder 19 of a camshaft of the high-pressure pump 1 translationally moving pump piston 20 and promotes the located in the pump working chamber 13 fuel via a high-pressure line 21 with inserted check valve 22 into the high pressure accumulator 2, from which the stored there, for example, under a pressure of about 1,600 bar stored fuel for injection into the combustion chambers.

The pump cylinder 19 is covered by a pump cylinder head 23, which may also be formed integrally with the pump cylinder 19. In the pump cylinder head 23, a recess 24 is incorporated, in which the inlet valve 12 is installed with the valve body 15. The valve body 15 has a guide bore 25 in which the valve pin 11 is sealingly guided. Above the valve body 15, a valve spring plate space 26 is formed, in which a valve spring 27 is arranged. The valve spring 27 is supported on the valve body 15 and opposite to a connected to the valve pin 11 valve spring plate 28 from. Above the valve spring plate 28, the recess 24 is closed by a screw 29 to the environment.

The valve spring 27 is designed so that upon a downward movement of the pump piston 20 by the negative pressure generated in the pump working space cooperating with the funded by the low-pressure pump 5 in the feed chamber 8 fuel opens the inlet valve 12 and Accordingly, the valve pin 11 is moved together with the valve plate 14 and the valve spring plate 28 in the position shown.

This opening movement and the subsequent closing movement of the inlet valve 12 can be influenced by an electromagnetic coil 30 which is in the in FIG. 1 embodiment is embedded in a recessed into the pump cylinder head 23 coil space 31. A connecting space 32 connecting the coil space 31 - for mounting the coil 30 - with the recess 24 can be closed by means of a plug, so that the coil space 31 is shielded from the recess 24 in a fuel-tight manner. The coil 30 is connected via a drive line 33 to an electronic control unit 34, which controls the flow of current to the coil 30 in response to desired operating conditions.

FIG. 2 shows a section of the in FIG. 1 illustrated high-pressure pump 1, wherein in the illustrated embodiment, in the pump cylinder head 23, a holding body 35 is inserted, which limits the recess 24. In the holding body 35 of the coil space 31 is inserted, in which the coil 30 is inserted. In the illustrated embodiment, the coil space 31 via the connecting space 32, which is closed by a seal acting as a stopper 36 relative to the recess 24 and the valve spring plate space 26. The connection space 32 may also extend over the entire height of the coil space 31 or omitted altogether. The holding body 35 is preferably made of a soft magnetic material, while the sealing ring 36 - if it is provided for closing an existing connection space 32 - can be made of an amagnetic (or even of a magnetic) material. The valve spring plate 28 is made of a magnetic material, such as steel, and acts as an armature in cooperation with the energized coil 30. In the illustrated embodiment, the valve spring plate 28 (in the closed state of the inlet valve) above the coil 30 and consequently the valve spring plate 28 in particular in the open state of the inlet valve 12 is influenced in energizing the coil 30 of the valve spring plate 28 with respect to its movement. Preferably, the coil 30 acts together with the valve spring plate 28 as a "magnetic brake" and thus brakes the opening movement of the valve pin 11 together with the valve spring plate 28 from. Of course, it is also possible, for example in another arrangement of the coil 30, to support the opening movement of the inlet valve 12 at least over a partial section of its movement.

The embodiment according to FIG. 3 is basically similar to that of FIG. 2 constructed, here in the holding body 35 three coil spaces 31 a, 31 b, 31 c are recessed, in each of which a coil 30 a, 30 b, 30 c is inserted. Furthermore, in this embodiment, the valve spring plate 28 on a Stellausprägung, which is formed by a total of three annular grooves 37 a, 37 b, 37 c. This Stellausprägung allows in conjunction with the individually energizable coils 30a, 30b, 30c a more accurate and sensitive influence on the movement of the intake valve 12th

In general, to carry out the function of the inlet valve 12 is that a magnetic field is formed by a continuous energization of the coil (s) 30, 30a, 30b, 30c in the (soft magnetic) material around the coil (s) 30, 30a, 30b, 30c Magnetic field lines act in the axial direction. The inlet valve 12 experiences a force in the opening direction via the inlet pressure originating from the low-pressure pump 5. The closing force of the valve spring 27 acts counter to this. The inlet valve 12 does not open until the pressure in the supply chamber 8 has dropped to such an extent that the hydraulic force produced by the fuel (possibly interacting with the pump piston 20 in the pump working chamber 13 when the pump piston 20 moves downwards Suction force) is greater than the closing force of the valve spring 27.

When the inlet valve 12 is opened, as soon as the valve spring plate 28 dips into the magnetic field of the coil (s) 30, 30a, 30b, 30c, the valve pin 11 experiences a force in a closing direction (counteracting the magnetic field). Thereby, the opening movement of the valve pin 11 is braked with the valve plate 14 and consequently also in this embodiment, a magnetic brake is realized. The inlet valve 12 makes due to the magnetic forces acting as a magnetic brake not full stroke, which is given about the mechanical stops, but only a partial stroke.

The height and the course of the partial stroke depend on the strength of the magnetic field. About the applied electric current can be accurately and sensitively control in this way the released with the inlet valve 12 flow cross-section.

In summary, the following variants can be implemented within the scope of the invention:

1. Amagnetic sealing ring variant

An amagnetic sealing ring 36 is used to seal the coil (s) 30, 30a, 30b, 30c from the fuel. The sealing ring 36 increases the effective magnetic field, resulting in lower energy consumption, and increases the robustness of the inlet valve 12 adjustment device consisting essentially of the spool (s) 30, 30a, 30b, 30c due to sealing against that in the recess 24 prevailing fuel pressure and compared to the fuel temperature. This embodiment causes an increase in the reliability of the intake valve 12 thus formed.

2. Inverse variant

In an inverse variant, a magnetic field is generated in the region of the lift of the intake valve 12, wherein the stroke is traversed when closing the intake valve 12. If the magnetic field is active when the coil (s) 30, 30a, 30b, 30c are energized, magnetic forces in the opening direction act on the inlet valve 12 and the closing of the inlet valve 12 is delayed. In combination with other embodiments, the inverse variant provides additional control of the intake valve 12. The lift of the intake valve 12 may be additionally affected, and thus the delivery rate of the high pressure pump 1 can be more accurately adjusted by more accurately metering fuel into the pump working space 13. As a result, a functional advantage of the high-pressure pump 1 is achieved. Furthermore, by the slowed valve closing pressure peaks by so-called "water hammer effects" (which are of course caused by the fuel as a fluid) can be effectively avoided.

3. Multi-coil variant with control characteristic on the valve spring plate 28

By using a plurality of coils 30a, 30b, 30c and a Stellausprägung on the valve spring plate 28, the achieved stroke of the intake valve 12 can be set more accurately. Various energization patterns with divisions on the various coils 30a, 30b, 30c can be implemented within the scope of the invention. Likewise, different Stellausprägungsmuster, for example by design of air gaps or introduction of soft magnetic material are provided. The accuracy of the flow control is thereby increased to achieve a further functional advantage.

FIG. 4a shows in the upper schematic diagram a arranged below the valve spring plate 28 coil 30 (see also FIG. 2 ) and in the two diagrams below the adjustable effect on the opening behavior of the intake valve 12.

In the upper diagram, the valve pin stroke V _{h of} the valve pin 11 is plotted against the crank angle KW. Dashed is not energized coil 30, the full opening movement and closing movement of the intake valve 12 and thus in particular of the filling of the pump working chamber 13 determining valve spring plate 28 relative to the valve seat 16 is shown. The inlet valve 12 makes the largest possible full opening stroke Vö _h . In contrast, the solid curve shows the opening movement and closing movement of the intake valve 12 with a limited Teilöffnungshub Tö _h , which adjusts itself when energized coil 30. This then reached Teilöffnungshub Tö _h corresponds to about half of the maximum adjustable Vollöffnungshubs Vö _h . In the diagram below, the flow rate Q, is shown, which is gradually adjusted against a limit.

In the embodiment according to FIG. 4b is the coil 30 above the valve spring plate 28 (see also FIG. 3 ). In this case, this embodiment is set so that the closing movement of the intake valve 12 is braked. The coil 30 cooperates with the valve spring plate 28 as a magnetic brake.

In the upper diagram is shown that in this embodiment, a design is such that the closing movement of the intake valve 12 caused by the immersed in the magnetic field of action of the coil 30 valve spring plate 28, the closing movement of the valve disc 14 in an end region E _{b is} delayed. Accordingly, an adjustment of the delivery also results in a limit, this limit is reached after an overshoot of the flow rate.

In both embodiments, the coil is continuously energized with, for example, approximately 2 amperes, so that a constant magnetic field with one with a likewise at least almost constant flux density [Tesla] (or magnetic induction) builds up. The energization is constant over the rotation of the crankshaft, for example in the illustrated range, it takes place as no change on the rotation of the crankshaft, such as in a conventional metering unit. Of course, it is provided to increase the absolute value of the current supply, for example, from 2 amperes to 4 amperes during the entire energizing phase, for example to increase the braking effect exerted by the coil 30 on the inlet valve 12. The even current dispenses with a power-intensive power amplifier. As a result, a cost-effective conversion of the fuel injection system from a control of the amount of fuel to be supplied by means of a conventional metering unit to the device according to the invention is possible.

Claims (10)

High-pressure pump for a fuel injection system of an internal combustion engine having a pump cylinder (19) covered by a pump cylinder head (23) and a cylinder bore (18), wherein in the cylinder bore (18) a pump piston (20) is translationally movable, of which in the cylinder bore (18) together with the pump cylinder head (23) a pump working space (13) is formed, which is connected via an inlet valve (12) with a low pressure system (5), and wherein the opening movement and / or the closing movement of a valve member (11) of the inlet valve (12) can be influenced by an actuator,
characterized in that at least one electromagnetic coil (30, 30a, 30b, 30c) acting as an armature acting magnetic component of the inlet valve (12) is present. High-pressure pump according to claim 1,
characterized in that the component at least during a portion of the opening movement and / or the closing movement of the inlet valve (12) with the coil (30, 30a, 30b, 30c) cooperates. High-pressure pump according to claim 1 or 2,
characterized in that the component is a valve spring plate (28). High-pressure pump according to one of the preceding claims,
characterized in that the coil (30, 30a, 30b, 30c) is embedded in a holding body (35) as part of the inlet valve (12). High pressure pump according to claim 4,
characterized in that the material of the holding body (35) is a soft magnetic material. High-pressure pump according to one of the preceding claims,
characterized in that the coil (30, 30a, 30b, 30c) is separated fuel-tight with respect to a fuel-filled valve spring plate space (26) of the inlet valve (12). High-pressure pump according to one of claims 3 to 6,
characterized in that the valve spring plate (28) has a Stellausprägung. High-pressure pump according to one of the preceding claims,
characterized in that at least two coils (30a, 30b, 30c) are provided adjacent to each other. High-pressure pump according to one of claims 3 to 8,
characterized in that the coil (30, 30a, 30b, 30c) is arranged in relation to the valve spring plate (28) that when energized coil (30, 30a, 30b, 30c), the opening movement of the inlet valve (12) can be influenced. High-pressure pump according to one of claims 3 to 8,
characterized in that the coil (30, 30a, 30b, 30c) is arranged in relation to the valve spring plate (28) that when energized coil (30, 30a, 30b, 30c), the closing movement of the inlet valve (12) can be influenced.

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