The invention concerns a lever device for a fuel injection valve, with a housing, at least one lever element, a drive element and an output element. The invention furthermore concerns a fuel injection valve for an internal combustion engine of a motor vehicle, comprising the lever device and a valve needle which is coupled to the output element or which forms the output element.
Fuel injection valves for an internal combustion engine of a motor vehicle can comprise actuators which are in particular formed as piezo-actuators. Such actuators comprise a piezo-ceramic material. Such actuators can change their linear extension depending on an electric field which acts in the piezo-ceramic material. The piezo-electric actuators used as servo components, in particular in fuel injection valves for internal combustion engines in motor vehicles, are arranged in a housing so that they can execute a stroke movement in the axial direction. The actuator can in particular be coupled to a lever device, by means of which the stroke of the actuator can be translated.
One embodiment provides a lever device for a fuel injection valve with a housing which has a housing recess, at least one lever element which is arranged in the housing recess and has a coupling portion which is coupled to a portion of the housing, a drive element which is arranged in the housing recess and is coupled to the at least one lever element to act on the at least one lever element in the direction of the force-action axis, and an output element arranged in the housing recess which is coupled to the at least one lever element such that the output element can be moved in the direction of the force-action axis by means of the at least one lever element, wherein the coupling portion of the lever element has at least one recess, by means of which at least two contact faces of the coupling portion are formed which are spaced apart from each other and lie on the portion of the housing.
In a further embodiment, the at least two contact faces of the coupling portion are formed as convex curved faces.
Another embodiment provides a fuel injection valve which comprises a lever device disclosed above, and a valve needle which is coupled to the output element or which forms the output element, wherein the drive element and the valve needle are coupled together via the lever device such that the valve needle in a closed position prevents a fluid flow through the fuel injection valve, and otherwise allows a fluid flow through the fuel injection valve.
Example embodiments of the invention are explained in more detail below with reference to the drawings, in which:
a show cross-sections through a lever device in various embodiments,
Embodiments of the invention provide a lever device for a fuel injection valve which is persistently reliable, and a fuel injection valve which has a long service life.
According to a first aspect, a lever device for a fuel injection valve includes a housing which has a housing recess, at least one lever element which is arranged in the housing recess and has a coupling portion which is coupled to a portion of the housing, a drive element which is arranged in the housing recess and is coupled to the at least one lever element to act on the at least one lever element in the direction of a force-action axis, and an output element arranged in the housing recess which is coupled to the at least one lever element such that the output element can be moved in the direction of the force-action axis by means of the at least one lever element. The coupling portion of the lever element has at least one recess, by means of which at least two contact faces of the coupling portion are formed which are spaced apart from each other and lie on the portion of the housing.
This has the advantage that the lever element can achieve a low stiffness in a region between the contact faces of the coupling portion. As a result, any mechanical irregularities on the at least one lever element and/or on the housing portion can only exert a slight influence on the movement of the lever element, and hence changes in the injection quantities can be kept small or avoided altogether. In this way a persistently reliable operation of the lever device and hence of the fuel injection valve is possible.
In one embodiment, the at least two contact faces of the coupling portion are formed as convex curved faces. This has the advantage that the friction and wear of the lever element can be very low. For example a rolling action of the lever element in relation to the housing portion allows the load on the contact faces to be kept small. Thus the at least one lever element allows a persistently reliable operation of the lever device.
According to a second aspect, a fuel injection valve comprises the lever device and a valve needle. The valve needle is coupled to the output element or forms the output element. The drive element and the valve needle are coupled together via the lever device such that the valve needle in a closed position prevents a fluid flow through the fuel injection valve, and otherwise allows this. Because of the distance between the at least two contact faces of the coupling portion, such a valve can be operated persistently reliably.
The fuel injection valve 10 has a housing 12. The housing 12 has several portions 12a, 12b. The housing 12 in particular has a disk-like portion 12a which is arranged between two tubular portions 12b of the housing 12. The disk-like portion 12a and the two tubular portions 12b are fixedly coupled together, and together form the housing 12. A housing recess 14 is formed in the housing 12, with a fluid inlet 16 and a fluid outlet 18. The injection valve 10 can be supplied with fuel in the region of the fluid inlet 16 via a connection (not shown), which is coupled hydraulically to the housing recess 14.
A valve needle 20 is arranged axially movably in the housing recess 14 and in a closed position closes an injection nozzle 22 and otherwise allows a fuel flow through the injection nozzle 22.
The injection valve 10 comprises a piezoelectric actuator 24. Instead of the piezoelectric actuator 24, another actuator can also be provided e.g. a magnetostrictive actuator or an electromagnetic actuator.
The fuel injection valve 10 furthermore comprises a drive element 26 coupled to the actuator 24. The drive element 26 preferably has a pin or a rod which respectively transmits the stroke or a drive force of the actuator 24. The actuator 24 and the drive element 26 are coupled together in the axial direction. A stroke of the drive element 26 is dependent on an axial expansion of the piezoelectric actuator 24, which in turn is dependent on a control signal which can be supplied to the piezoelectric actuator 24. The drive element 26 furthermore comprises a preferably bell-shaped component 27.
Furthermore a lever device 28 is arranged in the housing recess 14 of the fuel injection valve 10. The lever device 28 comprises the drive element 26 and a lever element 30 or several lever elements 30. In the embodiment shown, the lever device 28 had two lever elements 30 (see also
A force-action axis A of a drive force of the drive element 26 passes through the drive element 26 and continues through the output element 32 as a force-action axis of an output force.
In further embodiments, the force-action axis through the drive element 26 is offset to the force-action axis through the output element 32.
The lever elements 30 each have a coupling region 134. In the embodiment shown in
In the embodiment of the lever device 28 shown in
The lever element 30 has a coupling portion 34. The coupling portion 34 is coupled to the disk-like portion 12a of the housing (see also
In the embodiment of the lever element 30 shown in
The function method of the lever element 30 with the recess 36 of the coupling portion 34 will now be explained below with reference to
In
In
The lever element 30 has further coupling portions 42a, 42b (
As a result of the configuration of the lever elements 30 with the recess 36 of the coupling portion 34, the lever elements 30 can cooperate with the disk-like portion 12a of the housing 12 over a plurality of injection processes, without the transmission behavior between the lever elements 30 and disk-like portion 12a of the housing 12 changing decisively. Thus stable injection conditions of the fuel injection valve 10 can be maintained over a plurality of injection processes of the fuel injection valve 10. As a result, component tolerances—in particular of the lever element 30 and/or the disk-like portion 12a of the housing 12, and due for example to the protrusions 44, 44a—have only a very slight or no effect at all on the injection quantities of the fuel injection valve 10.
Number | Date | Country | Kind |
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10 2011 090 200.7 | Dec 2011 | DE | national |
This application is a U.S. National Stage Application of International Application No. PCT/EP2012/076158 filed Dec. 19, 2012, which designates the United States of America, and claims priority to DE Application No. 10 2011 090 200.7 filed Dec. 30, 2011, the contents of which are hereby incorporated by reference in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2012/076158 | 12/19/2012 | WO | 00 |