Patent Application
20140182550
The present disclosure generally relates to fuel injection systems with a common fuel rail and, in particular, to high pressure systems including a connector with an integrated flow limiter.
Many diesel engines utilize a common rail fuel system where a common rail supplies high-pressure fuel to associated fuel injectors via branch passages that typically extend through the engine head. These branch passages typically include a specialized pipe, which is often referred to as a quill. The quill may include a rounded end received by a conical seat of the high-pressure fuel inlet port of the fuel injector and another high-pressure fitting connection or seat at its opposite end to connect to the common rail. As such, each quill serves to deliver high-pressure fuel from the common rail into a corresponding fuel injector.
Known high pressure fuel injection systems frequently employ flow limiters configured to provide desired or predetermined amounts of fuel from the common rail, through the quill, and into a corresponding fuel injector for each injection cycle. Flow limiters also may serve to completely interrupt fuel flow from the common rail into an injector when a given injector fails so as to protect engines from overfueling. Typically, flow limiters interrupt flow when the injected quantity of fuel is determined to be in excess of a predetermined acceptable or normal amount. The injector itself generally controls the injected quantity of fuel.
A typical flow limiter only interrupts fuel flow if an error condition is sensed such as when an injector fails to stop injecting fuel. Commonly flow limiters are disposed between the common rail and the quills. Additionally, quills and flow limiters are usually distinct and separate components of a fuel injection system. Although widely used for larger engines because of associated increased costs with engine failures due to overfueling, it is less common for smaller engines to use flow limiters both because of lesser costs associated with overfueling as well as space constraints within a smaller engine.
Although high pressure injection systems using high pressure quills and separate flow limiters have generally worked as intended, there remains a continual need to reduce the number of fuel injector system components and to simplify component design and to make more efficient use of available space. There have been attempts in the past to include a flow limiter within a high-pressure connector or quill. U.S. Pat. No. 6,840,268 by Kennedy et al. describes a fuel injection system that uses a one-piece high-pressure connector having a fuel flow limiter disposed within the fuel passage. In the Kennedy reference, because the high-pressure connector is a one-piece elongated component that extends from the common rail into a corresponding injector, if there is a failure of any subcomponent of the connector it is unnecessarily cumbersome to access and replace a subcomponent connector part. As such, if one subcomponent part becomes inoperative, it would possibly necessitate a replacement of an entire connector and flow limiter combination.
Additionally, in the Kennedy reference, the end of the fuel flow limiter that is proximate to the common rail is a flush surface having sharp internal corners which have the capability of adding additional stress inside the high-pressure bore which in turn may lead to premature component failure. Also, in at least one embodiment of the Kennedy reference, the flow limiter is disposed downstream of the edge filter such that any debris generated by the flow limiter would not be screened out by the filter. The Kennedy device also utilizes a pressed-in retainer bushing to seal extremely high-pressure fluid using only the outward force exerted by the pressed-in bushing which would make it susceptible to displacement or movement.
In one aspect, a high-pressure connector or quill for a fuel injection system of an internal combustion engine includes a pair of elongated components linked together in fluid communication. The upstream elongated component includes a plenum chamber with an angled seat at its upstream end. The pair of elongated components is linked together by a linking component in a manner to permit fluid flow therethrough. A fuel flow limiter is slidably supported in the plenum chamber and includes a main body having a tapered end configured to be releasably received in the angled seat of the upstream end of the plenum chamber.
In another aspect, a fuel injection system for an internal combustion engine includes a high-pressure fuel source and fuel injectors operative in the engine to provide quantities of fuel into the combustion chambers. The fuel injection system also includes a number of high-pressure quills and corresponding fuel flow limiters as described above.
In a further aspect, an internal combustion engine includes an engine block with a number of cylinders with corresponding pistons. The pistons are each reciprocally supported in one of the cylinders. Each piston and cylinder combination defines a combustion chamber. The engine also includes a cylinder head mounted to the engine block. The engine also includes the fuel injection system, the high-pressure quills, and the fuel flow limiters as described above.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.
Many diesel engines may utilize a common rail fuel system where the common rail may supply high-pressure fuel to associated fuel injectors via branch passages that may extend through an engine head. These branch passages may include a specialized pipe, which is often referred to as a quill. A quill may be operative to deliver high-pressure fuel from the common rail into a corresponding fuel injector. With reference to
The second end 15 of the first elongated component, generally disposed downstream with respect to fluid flow, may include a fuel outlet 17 where the fuel may exit the first elongated component 12. A fuel passage 20 may extend through the first elongated component 12 from the fuel inlet 22 to the fuel outlet 17.
The fuel passage 20 may in part define a high-pressure bore or plenum chamber 28. The plenum chamber 28 may have an upstream end 19. The upstream end 19 of the plenum chamber 28 may include a seat 50 that may be configured to receive a fuel flow limiter 18 as will be described in greater detail herein. The seat 50 may be angled, curved, or otherwise configured as appropriate to receive the fuel flow limiter 18. For illustrative purposes, the seat 50 is shown and described in the present disclosure as an angled seat 50. The plenum chamber 28 may also include a downstream end 21 that may include the fuel outlet 17 of the first elongated component 12.
The high pressure quill 10 may include a second elongated component 14 that may include a first end 23 that may include a fuel inlet 25 that may be in fluid communication with the fuel passage 20 and the plenum chamber 28 of the first elongated component 12. The second elongated component 12 may include a second end 27 that may include a fuel outlet 24. The second elongated component 12 may also include an outlet fuel passage 26 extending through the second elongated component 14 from the fuel inlet 25 to the fuel outlet 24.
In order to link the first and second elongated components 12, 14 together, the first end 23 of the second elongated component 14 may be at least partially received within the second end 15 of the first elongated component 12 such that the fuel passage 20 of the first elongated component 12 and the outlet fuel passage 26 of the second elongated component 14 may be in fluid communication. A washer 46 may be disposed between the first end 23 of the second elongated component 14 and the second end 15 of the first elongated component 12 so as to form a seat for the spring 40. External seals 52, 54 may be disposed in corresponding annular grooves formed about the outer periphery of the high-pressure quill 10 to effect an air-tight seal between the quill 10 and a cylinder head 66 mounted on an engine block of an internal combustion engine.
A seal may be formed between the first and second components 12, 14 where they abut. The first end 23 of the second component 14 may be partially curved where it abuts the second end 15 of the first component 12. This arrangement may allow the second component 14 to slightly move or rotate relative to the first component 12 during assembly which may allow for easier fitting and aligning of the components. In other words, during assembly the components 12, 14 may slightly “bend” where they abut without losing the seal therebetween.
The high-pressure quill 10 may include a linking component 16 that may be at least partially disposed about the second end 15 of the first elongated component 12 and the first end 23 of the second elongated component 14 such that the first and second elongated components 12,14 may be fixedly connected in a manner to permit fluid communication between them. Alternatively, corresponding threads may be machined into components 12, 14.
As mentioned previously, a fuel flow limiter 18 may be slidably supported in the plenum chamber 28 of the fuel passage 20 of the first elongated component 12. The fuel flow limiter 18 may include a main body 30. The main body 30 may have a tapered end portion 48 configured to be releasably received in the angled seat 50 of the upstream end 19 of the plenum chamber 28.
The fuel flow limiter 18 may further include a high-pressure flow path 36 that may further form a part of the fuel passage 20. The high-pressure flow path 36 may include at least one fuel opening 34 that may disperse fuel into the plenum chamber 18. The fuel flow limiter 18 may further include an end portion 32 that may extend downstream from the main body 30. The end portion 32 may be of a smaller diameter than the main body 30. The end portion 32 may further include a stop valve 38 that may be substantially planar. The first end 23 of the second elongated component 14 may include a stop valve seat 42 that may also be substantially planar and may be configured to selectively receive the stop valve 38 of the fuel flow limiter 18 as shown in
The tapered end portion 48 of the main body 30 of the fuel flow limiter 18 may be substantially frustoconically shaped. The angled seat 50 of the plenum chamber 28 may also be substantially frustoconically shaped so that the tapered end portion 48 of the main body 30 of the fuel flow limiter 18 may be received within the angled seat 50 of the plenum chamber when the fuel flow limiter 18 is in a starting position as shown in
A biasing member 40, which may be a spring as shown in the Figures, may be supported within the plenum chamber 28. The biasing member 40 is operable to bias the main body 30 of the fuel flow limiter 18 into the starting position as shown in
As shown in
As further shown in
The high pressure quill 10 of the present disclosure has wide application in a variety of engine types including, for example, diesel engines, gasoline engines, and gaseous fuel-powered engines. The disclosed high pressure quill 10 may be implemented into the fuel system of any engine that utilizes a high pressure fuel supply and closed orifice-type fuel injectors where fabrication time and cost are concerns, and flow limiting is desired.
The operation of the high pressure quill 10 of the present disclosure will be described in greater detail with reference to
During an injection event, fuel is drawn from the plenum chamber 28 and the pressure in the chamber is thereby reduced. The high pressure on the fuel delivery side of the quill 10 causes a force imbalance on the body 30 of the fuel flow limiter. The flow limiter body 30 then moves into an operative position as shown in
After the completion of each injection event, the pressure in the plenum chamber 28 equalizes with the fuel supply pressure. As such, the force of the biasing member 40 moves the flow limiter body 30 back toward the angled seat 50 to its first position shown in
If an injector were to fail, pressure on the fuel output side of the flow limiter main body 30 exceeds the pressure in the plenum chamber 28 which causes the flow limiter body 30 to move down the entire length of the chamber 28 such that the stop valve seat 42 receives the stop valve 38 of the fuel flow limiter 18 as shown in
