Title of Invention

FUEL-INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE

Abstract

The fuel-injection device exhibits a high-pressure region that comprises of at least one high-pressure accumulator (16) in which fuel is stored at injection pressure and at least one injector (20) connected to the high-pressure accumulator (16) for fuel injection at a cylinder of the internal combustion engine. Apart from this the fuel-injection device exhibits a low-pressure region that is at least indirectly connected to a fuel storage tank (12). The high-pressure region exhibits a connection (40) to the low-pressure region, controlled subject to the fuel temperature in the high-pressure region, the connection being at least essentially closed at high fuel temperature so that the high-pressure region is separated from the low-pressure region and which is opened at lower fuel temperatures.

Full Text

FUEL-INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE Prior Art The invention emanates from a fuel-injection device for an internal combustion engine in accordance with the genre of Claim 1. This type of fuel-injection device is established in, for example, Diesel Motor Management, published by Vieweg, second edition 1998, pages 280 to 284. This fuel-injection device has a high-pressure region that comprises of a high-pressure accumulator and injectors that are connected to the same for fuel injection at a cylinder of the internal combustion engine. Apart from this, the high-pressure region comprises of a high-pressure pump through which fuel is conveyed to the high-pressure accumulator. The fuel-injection device, in addition, exhibits a low-pressure region that is at least indirectly connected to a fuel storage tank. The low-pressure region can, thereby, be a fuel storage tank or a runback to the fuel storage tank or a supply connection through which the intake side of the high-pressure pump is supplied with fuel from the fuel storage tank. A low-pressure pump can, thereby, be located in the supply connection through which fuel from the fuel storage tank is conveyed to the intake side of the high-pressure pump. The high-pressure region is separated from the low-pressure region in order to avoid fuel leakage. Fuel heats up when the internal combustion engine is in operation, particularly in the high-pressure region of the fuel-injection device. When the internal combustion engine is switched off after a long period of operation, the fuel cools in the high-pressure region, whereby the volume reduces, which could result in formation of vapour bubbles in the high-pressure region. This renders a later re-start of the interna! combustion engine difficult since the vapour bubbles in the high-pressure region have first to be disposed off before a fuel injection and, therewith, combustion can begin in the internal combustion engine. Advantages of the Invention The fuel-injection device, in accordance with the invention, with features according to Claim 1 has the comparative advantage that the formation of vapour bubbles during cooling down of fuel in the high-pressure region is avoided since fuel from the low-pressure region can flow into the high-pressure region to equalise the volume reduction and thus enables reliable starting of the internal combustion engine. Almost no or at least only very low leakage is thus present at high fuel temperatures so that no essentially increased fuel supply quantities are required in the high-pressure region. Beneficial designs and further development of the fuel-injection device in accordance with the invention are specified in the dependent Claims. The design according to Claim 2 enables a simple temperature-dependent control of the connection of the high-pressure region to the low-pressure region. The design according to Claim 3 enables a simple design of the valve mechanism. A long leak-proof gap is present in the design according to Claim 6 so that the connection to the low-pressure region can be securely closed at high fuel temperatures and no or only low leakage is present. The design according to Claim 7 or 8 enables a configuration of the valve mechanism that saves on installation space without any great additional constructive output. Drawing An exemplary embodiment of the invention is presented in the drawing and is described in greater detail in the subsequent description. Figure 1 is a schematic illustration of a fuel-injection device for an internal combustion engine and Figure 2 presents a magnified illustration of a section of the valve mechanism of the fuel-injection device according to Figure 1. Description of the Exemplary Embodiment A fuel-injection device for an internal combustion engine of a motor vehicle is presented in Figure 1. The internal combustion engine is preferably a self-igniting internal combustion engine and has at least one or several cylinders 6, of which only one is illustrated in Figure 1. The fuel-injection device exhibits one feed pump 10 through which fuel is conveyed from a storage tank 12 to a high-pressure pump 14. Fuel is conveyed through at least one hydraulic pipeline 15 under high pressure by the high-pressure pump 14 to a high-pressure accumulator 16. Injectors 20, located at the cylinders 6 of the internal combustion engine, are connected to the high-pressure accumulator by hydraulic pipelines 18. A control valve 22 is located at each injector 20 respectively, using which the injector 20 can be opened for a fuel injection and closed to end a fuel injection respectively. The control valves 22 of the injectors 20 are connected to an electronic controller 24 and are controlled by the same, subject to operating parameters of the internal combustion engine. The control valves 22 can respectively exhibit an electro-magnetic or a piezo-electric actuator. The fuel-injection device has a high-pressure region that comprises of the pressure side of the high-pressure pump 14, the pipeline 15 between the high-pressure pump 14 and the high-pressure accumulator 16, the high-pressure accumulator 16, the pipeline 18 from the high-pressure accumulator 16 to the injectors 20 and the injectors 20. High-pressure, which can range, for example, between 1200 to 2000 bar, created by the high-pressure pump 14 thereby prevails in the high-pressure region. The high-pressure can, if necessary, be variably set by a fuel measuring device 26 located between the feed pump 10 and the intake side of the high-pressure pump 14 and/or by a pressure control valve 28 located in the high-pressure region, subject to operating parameters of the internal combustion engine. The fuel measuring device 26 is controlled by the controller 24. subject to pressure required in the high-pressure region. The pressure control valve 28 can thus be controlled by the controller 24 and a runback 30 leads from this to the storage tank 12 through which fuel from the high-pressure region can be terminated. Apart from this, the fuel injection device exhibits a low-pressure region that comprises of the storage tank 12, the connection between the storage tank 12 and the intake side of the high-pressure pump 14 together with the feed pump 10 located therein and the runback 30 from the pressure control valve 28 to the storage tank 12. At least approximate ambient pressure, thereby, prevails in the low-pressure region or pressure created by the feed pump 10 that can, for example, range from approximately 2 to 10 bar. it is provided, in accordance with the invention, that the high-pressure region has a connection 40, which is controlled subject to the fuel temperature in the high-pressure region, to the low-pressure region that is at least basically closed at high fuel temperatures, so that the high-pressure region is separated from the low-pressure region, and that is opened at lower fuel temperatures. The connection 40 is controlled by a valve mechanism 42 that is influenced by fuel temperature in the high-pressure region. The valve mechanism 42 is described subsequently in greater detail by means of Figure 2. The valve mechanism 42 has a bi-metal switching equipment that has two elements 44, 46 made from metal possessing varied, preferably highly different thermal expansion coefficients. The element 44 with the higher thermal expansion coefficient, thereby, changes form with changing fuel temperature to a greater extent than element 46 with the lower thermal coefficient, whereby connection 40 can be closed and opened. Element 44 with the higher thermal expansion coefficient can, for example, be manufactured from aluminium and element 46 with the lower thermal coefficient can, for example, be manufactured from steel. Elements 44, 46 respectively have, for example, a sleeve-shaped design, whereby element 44 with the higher thermal expansion coefficient is located within the other element 46 with the lower thermal coefficient. A cross-section of the stream in the form of an annular channel 48, which is at least approximately closed at high fuel temperatures due to the higher expansion of the inner element 44 when compared to the outer element 46, is present between both elements at lower fuel temperatures. The inner element 44 is thereby filled with fuel from the high-pressure region. The annular channel 48 is connected by at least one port 50, in the shape of a bore hole for example, in the inner element 44 to the high-pressure region. The connection between the annular channel 48 and the high-pressure region in the interior of the inner element 44 can also be formed by a groove or a gap between a front side of element 44 and a boundary lying opposite this. Apart from this, the annular channel 48 is connected to the low-pressure region by at least one transfer region 52 in the outer element 46. An annular groove 54 that is connected to the low-pressure region, for example, by at least one bore 56 that opens in the annular groove 54 in the outer element 46 or by a longitudinal groove that leads away from the annular groove 54 at which a pipeline is connected that forms a connection 40 to the low-pressure region, can thereby be inserted in the transfer region 52 in the inner shell of the outer element 46. The at least one port 50 as a connection of the annular channel 48 to the high-pressure region and the transfer region 52 as a connection of the annular channel 48 to the low-pressure region are preferably located at a distance from one another in the direction of the longitudinal axis 45 of elements 44, 46. Through this configuration, the annular channel 48 and therewith the leak-proof gap formed at high fuel temperatures by closing the annular channel 48 exhibits a large length through which good sealing and therewith low leakage is achieved at high fuel temperatures. The valve mechanism 42 described above can be located at any position in the high-pressure region of the fuel-injection device, for example, at the high-pressure accumulator 16, in the pipeline 15 between the high-pressure pump 14 and the high-pressure accumulator 16, in one of the pipelines 18 between the high-pressure accumulator 16 and an injector 20, at an injector 20 or at a connecting element 60 of one of the pipelines 15, 18 at one of the components. The valve mechanism 42 is preferably integrated in one of these components or, as illustrated in Figure 1, in a connecting element 60, whereby the outer element 46 is formed by the component, a casing 62 of the component or a connecting element 60. Thus, only the inner element 44 and the pipeline 40 are required as additional components for the valve mechanism 42. The connecting element 60 can, for example, be a socket or a coupling nut for connecting a pipeline 15 or 18 to one of the components of the high-pressure region. At low fuel temperatures when the annular channel 48 is open, the inner element 44 is loaded at its internal side and at its external side at least approximately by the same pressure, so that no essential distortion of the inner-'element 44 is caused by the pressure. If the size of the annular channel 48 is reduced as a consequence of expansion of the inner element 44 due to increasing fuel temperatures, this results additionally in an expansion of the 'inner.element 44 and therewith a support during closing of the annular channel 48 due to the pressure that is then reduced in the annular channel 48 by occurring restrictions, that acts upon the outer side of the inner element 44 through high pressure acting upon the inner side of element 44. In consequence of the valve mechanism 42, the high-pressure region exhibits a variable leakage that can, nevertheless, be counterbalanced by corresponding control of the fuel measuring device 26 and/or of the pressure control valve 28 through the controller 24. In the case of the layout design of the valve mechanism 42 and also subject to the installation location, other influences have to be taken into consideration, if necessary, for example heating up of the valve mechanism 42 caused by radiation of heat or heat transmission from the internal combustion engine. claims 1. Fuel-injection device for an internal combustion engine with a high-pressure region that is comprised of at least one high-pressure accumulator (16) in which fuel is stored under injection pressure and at least one injector (20) connected to the high-pressure accumulator (16) for fuel injection at a cylinder of the internal combustion engine and with a low-pressure region that is connected at least indirectly to a fuel storage tank (12), characterised in that, the high-pressure region exhibits a connection (40) to the low-pressure region that is controlled subject to the fuel temperature in the high-pressure region and that is at least essentially closed at high fuel temperatures so that the high-pressure region is separated from the low-pressure region and that is open at lower fuel temperatures. 2. Fuel-injection device according to Claim 1, characterised in that, the connection (40) of the high-pressure region to the low-pressure region is controlled by a valve mechanism (42) that is influenced by fuel temperature in the high-pressure region. 3. Fuel-injection device according to Claim 2, characterised in that, the valve mechanism (42) exhibits a bi-metal switching equipment with at least two elements (44, 46) that are made of metals possessing different thermal expansion coefficients. 4. Fuel-injection device according to Claim 3, characterised in that, a cross-section of the flow (48) is released between the two elements (44, 46) at lower fuel temperatures and that the cross-section of the flow (48) is at least essentially closed by the element (44) with the higher thermal expansion coefficient at higher fuel temperatures. 5. Fuel-injection device according to Claim 4, characterised in that, the elements (44, 46) have a sleeve-shaped design, that the element (44) with the higher thermal expansion coefficient is located within the other element (46), that the interior of inner element (44) is filled with fuel from the high-pressure region and that the releasable cross-section of the flow is designed as an annular channel (48) between the elements (44, 46). 6. Fuel-injection device according to Claim 5, characterised in that, a connection (50) to the high-pressure region and a connection (52) to the low-pressure region open out in the annular channel (48) and that the ports of these connections (50 ; 52) are located offset to one another in the direction of the longitudinal axis (45) of elements (44 ; 46). 7. Fuel-injection device according to one of Claims 2 to 6, characterised in that, the valve mechanism (42) is located in a component of the high-pressure region, preferably in a casing, in a pipeline (15 ; 18) or in a connecting element (60) of a pipeline (15 ; 18). 8. Fuel-injection device according to Claim 5 or 6 and Claim 7, characterised in that, the outer element (46) is formed by the casing, the pipeline (15 ; 18) or the connecting element (60).

Documents:

3393-CHENP-2006 AMENDED CLAIMS 06-11-2012.pdf

3393-CHENP-2006 AMENDED PAGES OF SPECIFICATION 06-11-2012.pdf

3393-CHENP-2006 CORRESPONDENCE OTHERS 31-05-2012.pdf

3393-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 06-11-2012.pdf

3393-CHENP-2006 FORM-3 06-11-2012.pdf

3393-CHENP-2006 POWER OF ATTORNEY 06-11-2012.pdf

3393-CHENP-2006 OTHER PATENT DOCUMENT 06-11-2012.pdf

3393-chenp-2006-abstract.pdf

3393-chenp-2006-claims.pdf

3393-chenp-2006-correspondnece-others.pdf

3393-chenp-2006-description(complete).pdf

3393-chenp-2006-drawings.pdf

3393-chenp-2006-form 1.pdf

3393-chenp-2006-form 26.pdf

3393-chenp-2006-form 3.pdf

3393-chenp-2006-form 5.pdf

3393-chenp-2006-pct.pdf