Fuel injection device

Abstract

Fuel injection device (32) comprising the following: a nozzle element (56) which has the following features: a top part (64); at least one measuring opening (80) which is arranged in the tip part (64); a basic part (78); and a conically tapered, internal receiving surface (76) arranged on the base part (78); and a needle valve element (58) which is slidably arranged within the nozzle element (56) and has the following features: a tip end (82) which is configured to selectively restrict a fuel flow through the at least one metering opening (80); a base end (100); and a conically tapered, external bearing surface (86) arranged between the tip end (82) and the base end (100), wherein the conically tapered, external bearing surface (86) is configured to engage with the conically tapered, internal receiving surface (76) to restrict the fuel flow through the at least one metering orifice (80), with an outer diameter larger than the outer diameter of the base end (100) of the needle valve element (58).

Description

Technical field

[0001] The present disclosure relates to a fuel injection device, and in particular to a fuel injection device with a reserve leak limiting device. background

[0002] Common-rail fuel systems (common rail = common pressure line) typically employ closed-loop multiple-nozzle fuel injectors to deliver high-pressure fuel into the combustion chambers of an engine. Each of these fuel injectors may have a nozzle assembly with a cylindrical bore, comprising a nozzle supply port and a nozzle outlet. A needle check valve may be movably positioned within the cylinder bore and biased to a closed position, where the nozzle outlet is blocked. Responding to any injection request, the needle check valve can be selectively moved to open the nozzle outlet, allowing high-pressure fuel to flow from the nozzle supply port into the combustion chamber.

[0003] During operation of the fuel injection system, it is possible for a tip portion of the nozzle to fail, leaving the nozzle continuously open. To ensure that high-pressure fuel is not continuously pumped into the combustion chamber, the common-rail fuel system can employ a leak-limiting device to restrict fuel leakage through the nozzle. Such a device is described in U.S. Patent 6,109,542 A (the '542 patent), issued to Morris et al. on August 29, 2000. The '542 patent describes a nozzle cavity that accommodates a nozzle valve element and a limiting valve located upstream of the nozzle cavity. The limiting valve is moved to an open position just before an intended injection to selectively connect the high-pressure fuel to the nozzle cavity.Between the desired fuel injections into an associated combustion chamber, the limiting valve element moves to a closed position to block the connection of the high-pressure fuel to the nozzle cavity. When the limiting valve element is in the closed position, only the fuel already in the nozzle cavity can leak into the combustion chamber in the event of nozzle tip failure.

[0004] Although the limiting valve of patent 542 can minimize the extent of fuel leakage from the nozzle cavity upon nozzle failure, it still allows all the fuel already in the nozzle cavity to drain into the associated combustion chamber following each intended injection. This amount of fuel that can drain into the combustion chamber could still significantly affect engine performance, fuel consumption, and emissions.

[0005] Additionally, the limiting valve does not restrict targeted injections. In particular, even if the injection device of patent 542 has suffered a nozzle failure, the limiting valve of patent 542 will still move to the open position in response to an injection request. Under conditions of nozzle failure, targeted injection could also result in rough engine operation, poor fuel economy, and increased emissions.

[0006] Furthermore, the limiting valve of patent 542 can be complex and expensive, and can increase the unreliability of the common rail system that uses it. In particular, because the limiting valve is an additional component and performs no function other than limiting leakage, the overall cost of the common rail system must increase. The additional components of the limiting valve also contribute to the overall complexity and number of possible failure operating conditions of the common rail system.

[0007] Furthermore, US 5 463 996 A discloses a hydraulically actuated, electronically controlled fuel injection device.

[0008] The fuel injection device of the present disclosure solves one or more of the problems set out above. Summary of the invention

[0009] The object of the present invention is achieved by a fuel injection device according to claim 1, a method for operating a fuel injection device according to claim 6, and a fuel system according to claim 10. The dependent claims relate to preferred embodiments of the invention. One aspect of the present disclosure is directed to a fuel injection device. The fuel injection device comprises, among other things, a nozzle element with a tip portion, at least one metering opening arranged on the tip portion, a base portion, and a conically tapered, internal seating or receiving surface arranged on the base portion.The fuel injection device also includes a needle valve element, which is slidably arranged within the nozzle element and has a tip end configured to selectively restrict the fuel flow through the at least one metering orifice, a base end, and a conically tapered, outer seat or bearing surface located between the tip end and the base end. The conically tapered, outer bearing surface is configured to engage with the conically tapered, inner receiving surface to restrict the fuel flow through the at least one metering orifice and has a hydraulic surface area larger than the hydraulic surface area of ​​the base end of the needle valve element.

[0010] Another aspect of the present disclosure relates to a fuel injection device. The fuel injection device comprises a nozzle element with a tip section, at least one metering orifice arranged on the tip section, a base section, and a conically tapered, internal receiving surface arranged on the base section. The fuel injection device also comprises a needle valve element, which is slidably arranged within the nozzle element and has a tip end configured to selectively restrict the fuel flow through the at least one metering orifice, a base end, and a conically tapered, external bearing surface arranged between the tip end and the base end.The conically tapered outer contact surface is configured to engage with the conically tapered inner receiving surface in order to restrict the fuel flow through the at least one metering orifice, and has a cone angle that is greater than the cone angle of the conically tapered inner receiving surface.

[0011] A further aspect of the present disclosure relates to a method for operating a fuel injection device. The method comprises directing pressurized fuel to a nozzle element with at least one metering port at a tip end. The tip end has at least one conically tapered, internal receiving surface. The method further comprises selectively moving a needle valve element with at least one conically tapered, external bearing surface between a position in which fuel can flow through the at least one metering port and a second position in which the conically tapered, external bearing surface engages with the conically tapered, internal receiving surface, i.e., forms a seat, in order to restrict the fuel flow through the at least one metering port.The method also includes engaging a second conically tapered, outer bearing surface of the needle valve element with a second conically tapered, inner receiving surface of the nozzle element to restrict fuel flow when the first conically tapered, inner and outer receiving and bearing surfaces cannot engage. Brief description of the drawings Fig. Figure 1 is a schematic and diagram-like illustration of an exemplary disclosed fuel system; Fig. 2A is a cross-sectional view of an exemplary disclosed fuel injection device for the fuel system of the Fig. 1; and Fig. 2B is a cross-sectional view of a part of the in Fig. Fuel injection device shown in 2A. Detailed description

[0012] An exemplary embodiment of an engine 10 with a fuel system 12 is shown in Fig. Figure 1 illustrates this. For the purposes of this disclosure, the engine 10 is depicted and described as a four-stroke diesel engine. However, the person skilled in the art will recognize that the engine 10 can be any other type of internal combustion engine, such as an engine powered by gasoline or gaseous fuel. The engine 10 can have an engine block 14 defining a plurality of cylinders 16, a piston 18 slidably arranged in each cylinder 16, and a cylinder head 20 associated with each cylinder 16.

[0013] The cylinder 16, the piston 18, and the cylinder head 20 can form a combustion chamber 22. In the illustrated embodiment, the engine 10 has six combustion chambers 22. However, it is considered that the engine 10 may have a larger or smaller number of combustion chambers 22, and that the combustion chambers 22 may be arranged in an in-line configuration, a V-configuration, or any other suitable configuration.

[0014] As also in Fig. As shown in Figure 1, the engine 10 can have a crankshaft 24 which is rotatably arranged in the engine block 14. A connecting rod 26 can connect each piston 18 to the crankshaft 24, so that a sliding movement of the piston 18 within each respective cylinder 16 results in a rotation of the crankshaft 24. Similarly, a rotation of the crankshaft 24 can result in a sliding movement of the piston 18.

[0015] The fuel system 12 comprises components that work together to deliver injections of pressurized fuel into each combustion chamber 22. In particular, the fuel system 12 may include a tank 28 configured to contain a fuel supply and a fuel pump assembly 30 configured to pressurize the fuel and deliver the pressurized fuel to a plurality of fuel injection devices 32 through a common manifold 34.

[0016] The fuel pump assembly 30 can include one or more pump devices that increase the fuel pressure and direct one or more pressurized fuel streams to the common manifold 34. In one example, the fuel pump assembly 30 includes a low-pressure source 36 and a high-pressure source 38 arranged in series and fluidically connected by a fuel line 40. The low-pressure source 36 can be a transfer pump configured to provide a low-pressure feed to the high-pressure source 38. The high-pressure source 38 can be configured to receive the low-pressure feed and increase the fuel pressure to a range of approximately 40–190 MPa. The high-pressure source 38 can be connected to the common manifold 34 by a fuel line 42.A check valve 44 can be arranged in the fuel line 42 to provide a fuel flow in one direction from the fuel pump arrangement 30 to the common manifold 34.

[0017] One or both of the low-pressure and high-pressure sources 36, 38 can be operationally connected to the engine 10 and driven by the crankshaft 24. The low-pressure and / or high-pressure sources 36, 38 can be connected to the crankshaft 24 in any manner that is readily apparent to a person skilled in the art, whereby a rotation of the crankshaft 24 will result in a corresponding rotation of the pump drive shaft. For example, a pump drive shaft 46 of the high-pressure source 38 is connected in Fig. 1 shown such that it is connected to the crankshaft 24 by a gear or drive train 48. However, it is considered that the low-pressure and / or high-pressure sources 36, 38 may alternatively be driven electrically, hydraulically, pneumatically or in any other suitable manner.

[0018] The fuel injection devices 32 can be arranged in the cylinder heads 20 and connected to the common manifold 34 by a plurality of fuel lines 50. Each fuel injection device 32 can be operated to inject a quantity of pressurized fuel into an associated combustion chamber 22 at predetermined times with predetermined fuel pressures and fuel flow rates. The fuel injection devices 32 can be actuated hydraulically, mechanically, electrically, or pneumatically.

[0019] The timing of fuel injection into the combustion chamber 22 can be synchronized with the movement of the piston 18. For example, fuel can be injected as the piston 18 approaches top dead center in a compression stroke to allow compression-ignited combustion of the injected fuel. Alternatively, fuel can be injected as the piston 18 begins the compression stroke, on its way to top dead center for homogeneous compression-ignited charge (HCCI) operation. Fuel can also be injected as the piston 18 moves from top dead center to bottom dead center during an expansion stroke for late post-injection to create a reducing atmosphere for aftertreatment regeneration.

[0020] As in Fig. As illustrated in Figure 2A, each fuel injection device 32 can be a closed-nozzle fuel injection unit. In particular, each fuel injection device 32 can have a nozzle housing 52 which accommodates a guide 54, a nozzle element 56, and a needle valve element 58.

[0021] The nozzle housing 52 can be a cylindrical element configured for mounting in the cylinder head 20. The nozzle housing 52 can have a central chamber 60 to accommodate the guide 54 and the nozzle element 56, and an opening 62 through which a pointed end 64 of the nozzle element 56 can protrude. A sealing element, such as an O-ring 66, can be arranged between the guide 54 and the nozzle element 56 to limit fuel leakage from the fuel injection device 32.

[0022] The guide 54 can also be a cylindrical element with a central clearance 68 configured to accommodate the needle valve element 58. One or more fuel supply passages 70 can be provided in the guide 54 to allow a connection between the pressurized fuel from the fuel line 50 and the nozzle element 56.

[0023] The nozzle element 56 can also be a cylindrical element with a central clearance 72, configured to receive the needle valve element 58. In particular, the nozzle element 56 can have a first conically tapered, internal receiving surface 74 located at the tip end 54, and a second conically tapered, internal receiving surface 76 located at a base end 78. As in Fig. As illustrated in Figure 2B, the second conically tapered, inner receiving surface 76 can have a cone angle of θ1. One or more of the measuring openings 80, which are located in Fig. 2A can be seen, may be located at a tip end 64 to allow the injection of pressurized fuel from the central free space 72 into the combustion chamber 22.

[0024] The needle valve element 58 can be an elongated cylindrical element, which is slidably arranged in the housing guide 54 and the nozzle element 56. The needle valve element 58 can be movable between a first position in which a pointed end 82 of the needle valve element 58 restricts fuel flow through the metering ports 80, and a second position in which the metering ports 80 are unrestricted to allow fuel flow into the combustion chamber 22. The needle valve element 58 can have a first conically tapered, external bearing surface 84 and a second conically tapered, external bearing surface 86.The first conically tapered, outer bearing surface 84 can be configured to rest on the first conically tapered, inner receiving surface 74 of the nozzle element 56, while the second conically tapered, outer bearing surface 86 can be configured to rest on the second conically tapered, inner receiving surface 76. As in . Fig. As illustrated in Figure 2B, the second conically tapered, outer bearing surface 86 can have a cone angle θ2 that is greater than θ1. When the first conically tapered, outer bearing surface 84 of the needle valve element 58 engages with the first conically tapered, inner receiving surface 74 of the nozzle element 56 (see Figure 2B), the following applies: Fig. 2A), i.e., forming a seat, the second conically tapered, inner and outer receiving and support surfaces 86, 76 are not engaged. The distance “d”, which in Fig. As illustrated in Figure 2B, the vertical distance between an outer circumference 88 of the second conically tapered, outer bearing surface 86 and the second conically tapered, inner receiving surface 76 can be represented when the first conically tapered, inner receiving and bearing surfaces 84, 74 are engaged and the needle valve element 58 is in the first position.

[0025] The needle valve element 58 can normally be biased towards the first position. In particular, as in Fig. As shown in Figure 2A, each fuel injection device 32 can have a spring 90 arranged between a stop 92 of the guide 54 and a seat 94 of the needle valve element 58 to axially bias the tip end 82 towards the metering ports 80. The difference between the uncompressed length of the spring 90 and the compressed length when the needle valve element 58 is in the first position can be greater than the distance “d”. Alternatively, it is considered that the difference between the uncompressed length of the spring 90 and the compressed length when the needle valve element 58 is in the first position need not be greater than the distance “d”. A first spacer 96 can be arranged between the spring 90 and the stop 92, and a second spacer 98 can be arranged between the spring 90 and the seat 94 to reduce wear on the components within the fuel injection device 32.

[0026] The needle valve element 58 can have multiple hydraulic actuation surfaces. In particular, the needle valve element 58 can have a base end which has a hydraulic surface 100 that tends to drive the needle valve element 58 to a first or closed position when pressurized fuel acts upon it, and a hydraulic surface 104 that tends to act against the preload of the spring 90 and drive the needle valve element 58 in the opposite direction to the second or open position. The size of the hydraulic surface 104 can be smaller than the size of a hydraulic surface defined by the outer circumference 88. For example, the area of ​​the hydraulic surface 104 can be less than half the area of ​​the hydraulic surface defined by the outer circumference 88.

[0027] An actuating device 106 can be arranged opposite the tip end 82 of the needle valve element 58 to initiate movement of the needle valve element 58. As already described, the Fig. 2A and Fig. 2B illustrates hydraulically driven fuel injection devices. In particular, the actuating device 106 can selectively connect the hydraulic surface 100 either to the fuel pressure from the fuel supply passages 70 or to a (not shown) drain line leading to the tank 28 (see Fig. 1) This selective connection can generate force imbalances that move the needle valve element 58 between the first or closed position and the second or open position. The operation of the actuating device 106 is described in more detail below. Industrial applicability

[0028] The fuel injection device of the present disclosure has widespread applications in a variety of engine types, including, for example, diesel engines, gasoline engines, and gaseous fuel-powered engines. The disclosed injection device can be provided in any engine that uses a pressurized fuel system, which has fuel injection devices with closed metering ports, where limiting fuel leakage into the associated combustion chambers after nozzle tip failure is desirable. The operation for limiting fuel leakage of the fuel injection device 32 is now explained.

[0029] The needle valve element 58 can be moved by an imbalance of the force generated by the fluid pressure. For example, when the needle valve element 58 is in the first or closed position, pressurized fuel from the fuel supply passages 70 can act on the hydraulic surface 100. The force of the spring 90, combined with the hydraulic force generated on the hydraulic surface 100, is greater than an opposing force generated on the hydraulic surface 104, causing the needle valve element 58 to remain in the first position, in which the first tapered, outer bearing surface 84 engages with the first tapered, inner receiving surface 74 to restrict the fuel flow through the metering ports 80.To open the metering ports 80 and inject the pressurized fuel into the combustion chamber 22, the actuating device 106 can selectively drain the pressurized fuel from the hydraulic surface 100. This reduction in pressure acting on the hydraulic surface 100 allows the opposing force acting on the hydraulic surface 104 to overcome the preload force of the spring 90, thereby moving the needle valve element 58 to the open position.In order to close and restrict the fuel flow through the metering orifices 80, the actuating device 106 can similarly selectively connect the pressurized fuel from the fuel supply passages 70 to the hydraulic surface 100 in order to overcome the force generated by the hydraulic surface 104 and to cause the needle valve element 58 to move to the first position with the preload of the spring 90.

[0030] Over time, the tip 64 of the nozzle element 56 can erode, wear down, and / or break off, leaving the tip 64 open. The wear and / or breakage can be severe enough that the needle valve element 58 is unable to adequately restrict the fuel flow through the metering ports 80 at the tip 64. Without intervention, pressurized fuel may be allowed to spray freely into the combustion chamber 22, causing rough engine running 10, poor fuel efficiency, and / or increased exhaust emissions.

[0031] Upon wear and / or breakage of the tip end 64, the needle valve element 58 can descend beyond the first position and further into the nozzle element 56 until the circumference 88 of the second conically tapered, outer bearing surface 86 engages with the second conically tapered, inner receiving surface 76. When the outer circumference 88 of the second conically tapered, outer bearing surface 86 engages with the second conically tapered, inner receiving surface 76, the tip end 64 and the nozzle element 56 can be substantially isolated from pressurized fuel. The uncompressed length of the spring 90 is selected to provide for the additional movement of the needle valve element over the distance "d".

[0032] The angle and outer circumference 88 of the second conically tapered, outer contact surface 86 provide leakage limitation functions even during targeted injections. In particular, because the cone angle θ2 is larger than the cone angle θ1, it is ensured that the outer circumference 88 of the second conically tapered, outer contact surface 86 engages with and seals against the second conically tapered, inner receiving surface 76.Because the outer circumference 88 defines an area of ​​the hydraulic surface that is larger than the area of ​​the hydraulic surface 104, the force generated on the surfaces of the second spacer 98 and the seat surface 94 when the outer circumference 88 is sealed against the second conically tapered, internal receiving surface 76, in conjunction with the force of the spring 90, is large enough to overcome the force generated on the hydraulic surface 104, even when the pressurized fuel is diverted from the hydraulic surface 100 through the actuating device 106.

[0033] Numerous advantages of the fuel injection device 32 can be realized compared to prior art fuel injection devices. In particular, because the leakage limitation function of the fuel injection device 32 is performed by existing components of the fuel injection device 32, namely the existing needle valve element 58 and the nozzle element 56, the overall cost, complexity, and potential failure of the fuel system 12, which the fuel injection device 32 employs, are kept low. Because the needle valve element 58 will continuously restrict the fuel flow through the nozzle element 56, even during targeted injections, the engine's performance 10, fuel efficiency, and exhaust emissions can also be improved.Because the needle valve element 58 restricts the fuel flow through the nozzle element 56 and not through an upstream component, the amount of fuel that can leak from the fuel injection device 32 into the combustion chamber 22 during a nozzle tip failure can be minimized.

[0034] It will be obvious to those skilled in the art that various modifications and variations can be made to the fuel injection device of the present disclosure without deviating from the scope of the following claims. Other embodiments will become apparent to those skilled in the art from a consideration of the description and from a practical implementation of the injection device disclosed herein.

Claims

[1] Fuel injection device (32) comprising: a nozzle element (56) which has the following features: a top part (64); at least one measuring opening (80) which is arranged in the tip part (64); a basic part (78); and a conically tapered, internal receiving surface (76) arranged on the base part (78); and a needle valve element (58) which is slidably arranged within the nozzle element (56) and has the following features: a tip end (82) which is configured to selectively restrict a fuel flow through the at least one metering opening (80); a base end (100); and a conically tapered, external bearing surface (86) arranged between the tip end (82) and the base end (100), wherein the conically tapered, external bearing surface (86) is configured to engage with the conically tapered, internal receiving surface (76) to restrict the fuel flow through the at least one metering orifice (80), with an outer diameter larger than the outer diameter of the base end (100) of the needle valve element (58). [2] Fuel injection device (32) according to claim 1, wherein the outer diameter of the conically tapered, external support surface (86) is at least twice as large as the outer diameter of the base end (100) of the needle valve element (58). [3] Fuel injection device (32) according to claim 1, wherein the conically tapered, inner (76) and outer (86) receiving and support surfaces are each first conically tapered, inner and outer receiving and support surfaces (76, 86); wherein the nozzle member (56) further comprises a second conically tapered, inner receiving surface (74) arranged on the tip part (64); and wherein the needle valve member (58) further comprises a second conically tapered, outer support surface (84) configured to engage with the second conically tapered, inner receiving surface (74) in order to restrict the fuel flow through the at least one metering orifice (80). [4] Fuel injection device (32) according to claim 3, wherein the first conically tapered, inner and outer receiving and support surfaces (76, 86) are separated by a distance when the second conically tapered, inner and outer receiving and support surfaces (74, 84) are engaged. [5] Fuel injection device (32) according to claim 4, further comprising a spring (90) which is configured to bias the needle valve member (58) in engagement with the nozzle member (56), wherein an uncompressed length of the spring (90) is greater than a compressed length of the spring (90) when the second conically tapered, inner and outer receiving and support surfaces (74, 84) are engaged, at least by the distance that separates the first conically tapered, inner and outer receiving and support surfaces (76, 86). [6] Method for operating a fuel injection device (32) comprising the following: Conveying pressurized fuel to a nozzle chamber (56) with at least one metering opening (80) at a tip end (64), wherein the tip end (64) has at least one conically tapered, internal receiving surface (74); selective movement of a needle valve element (58) with at least one conically tapered, outer receiving and bearing surface (84) between a first position in which fuel may flow through the at least one metering orifice (80) and a second position in which the at least one conically tapered, outer bearing surface (84) engages with the at least one conically tapered, inner receiving surface (74) in order to restrict fuel flow through the at least one metering orifice (80); Engaging a second conically tapered, outer contact surface (86) of the needle valve element (58) with a second conically tapered, inner receiving surface (76) of the nozzle element (56), to restrict fuel flow when the first conically tapered, inner and outer receiving and bearing surfaces (74, 84) cannot engage. [7] Method according to claim 6, wherein the engagement comprises moving the needle valve member (58) from the first position beyond the second position. [8] Method according to claim 6, wherein an inner cone angle (θ2) of the second conically tapered, outer support surface (86) is larger than an inner cone angle (θ1) of the second conically tapered, inner receiving surface (76), and wherein the engagement comprises bringing an outer circumference (88) of the second conically tapered, outer support surface (86) into engagement with the second conically tapered, inner receiving surface (76). [9] Method according to claim 6, further comprising keeping the second conically tapered, inner and outer receiving and support surfaces (76, 86) engaged during a targeted actuation of the fuel injection device (32). [10] Fuel system (12) for an engine (10) comprising the following: a tank (26) which is designed to contain a supply of fuel; a fuel pump arrangement (30) configured to pressurize the fuel; a common collection line (34) designed to receive the pressurized fuel; and a plurality of fuel injection devices (32) according to any one of claims 1-5, wherein each of the plurality of fuel injection devices (32) is arranged in parallel flow media connection with the common manifold (34) and further comprises the following: an injection device body (52) with a central bore (60); a guide (54) which is arranged in the central bore (60) of the injection device body (52) and has a central guide bore (68); wherein the nozzle element (56) is arranged in the central guide bore (68); and wherein the conically tapered, external intake and The contact surface (86) also has an internal cone angle (θ2) that is larger than an internal cone angle (θ1) of the conically tapered, internal receiving surface (76).

Images