Patent Application
20210156349
The field of the invention relates to opposed-piston engines equipped with fuel injectors. More specifically, the field of the invention concerns a fuel injector assembly uniquely constructed to mount a fuel injector to the cylinder block of an opposed-piston engine for direct side injection of fuel into a cylinder.
An opposed-piston engine is an internal-combustion engine characterized by an arrangement of two pistons disposed in the bore of a cylinder for reciprocating movement in opposing directions along a longitudinal axis of the cylinder. An opposed-piston, internal combustion engine differs in many respects from a conventional internal combustion engine, which has a single piston in a cylinder. In an opposed-piston engine, a combustion chamber is formed between the end surfaces of two opposed pistons in a zone of a cylinder, where combustion occurs; in a conventional engine, a combustion chamber is formed between a cylinder head and the end surface of the single piston moving in the cylinder. In an opposed-piston engine, air enters a cylinder through a piston-controlled intake port in the cylinder, near one of its two ends, and exhaust exits the cylinder through a piston-controlled exhaust port that opens through the cylinder, near the other of its two ends. In a conventional engine air and exhaust pass through one end of the cylinder via respective valve-controlled intake and exhaust ports in the cylinder head.
In a conventional engine with fuel injection, a fuel injector for a cylinder is mounted to the cylinder head, in close proximity to the cylinder's intake and exhaust ports. The fuel injector is positioned to inject a plume of fuel into the bore of the cylinder, through the end of the cylinder that seats against the cylinder head. In these cases the direction of fuel injection is toward the end surface of the piston, usually along the longitudinal axis of the cylinder. In an opposed-piston engine, the combustion chamber is defined in an intermediate portion of the cylinder, between the cylinder's intake and exhaust ends. A fuel injector is typically located adjacent to the sidewall in the intermediate portion of the cylinder, between respective top center (TC) locations of the piston end surfaces, with its nozzle oriented toward the cylinder's longitudinal bore axis. This results in a direct side injection configuration that is characteristic of opposed-piston engine design. That is to say, fuel is injected directly into the combustion chamber, through the sidewall of the cylinder, across (transverse to) the longitudinal bore axis.
In a conventional internal combustion engine equipped with a fuel injection system, a fuel injector is typically mounted to, and retained on, the cylinder head by means of a clamping arrangement that acts between the fuel injector and the cylinder head. Such a clamping arrangement exerts forces on the deck of the cylinder head, such that the deck face of the cylinder head may bulge or bow into the combustion chamber. These deformations occur in the cylinder head, and have little or no effect on the cylinder itself.
In an opposed-piston engine, there is no cylinder head where a fuel injector can be mounted. Instead, a fuel injector is typically mounted to a cylinder block, at a location containing a section of the cylinder wall where the combustion chamber is formed, that is to say, in the intermediate portion of the cylinder, far away from both the intake port and the exhaust port. Care must be taken to ensure that any means designed for mounting a fuel injector not deform the cylinder wall to such a degree that the bore distorts from some desired shape designed for an optimal sliding piston/bore interface. Such distortions can cause scuffing in the piston/cylinder bore interface, which can reduce the engine's durability and operational lifetime.
Accordingly, there is a need for a fuel injector assembly constructed to mount a fuel injector on the cylinder block of an opposed-piston engine and retain the fuel injector in operative communication with the bore of a cylinder, while causing little or no distortion of the cylinder bore.
A fuel injector mounting assembly for mounting a fuel injector on the cylinder block of an opposed-piston engine includes a sleeve, a clamp, threaded fasteners, and a spanner nut. The sleeve sheathes at least a nozzle portion of the fuel injector. The clamp has a first opening for the fuel injector and openings to accommodate the threaded fasteners. The threaded fasteners pass through the openings in the clamp to be secured in threaded openings in the cylinder block of the opposed-piston engine. The spanner nut is configured to be threadedly received on the sleeve and seated against the cylinder block in such a way as to resist or diminish an axial force applied to the fuel injector by the clamp which would otherwise be directed against a cylinder wall.
An opposed-piston engine includes the fuel injector mounting assembly described herein. Such an opposed-piston engine includes a cylinder block and the fuel injector mounting assembly with a sleeve, a clamp, threaded fasteners, and a spanner nut. The cylinder block has at least one cylinder, a recess for receiving the fuel injector with the sleeve, and threaded securing openings to receive the threaded fasteners. The spanner nut is configured to be threadedly received on the sleeve and seated against the cylinder block in such a way as to resist or diminish an axial force applied to the fuel injector by the clamp. An opposed-piston engine configuration with a fuel injector mounting assembly and cylinder block according to the invention reduces or eliminates cylinder bore deformation that is attributable to the presence of fuel injectors.
In an uniflow-scavenged, two-stroke opposed-piston engine, a fuel injector mounting assembly is used to mount and retain a fuel injector on a cylinder block, in operative fuel injecting communication with a cylinder of the engine. The fuel injector mounting assembly is configured to reduce, or prevent, cylinder bore distortion associated with, or caused by, damping forces acting against the fuel injector in the direction of the cylinder. Embodiments of the fuel injector mounting assembly and its components are described herein, as is a representative opposed-piston engine configuration that incorporates a fuel injector mounting assembly according to the invention.
The fuel injector is clamped to the cylinder block 110 by means of a clamping arrangement that secures the fuel injector 160, sheathed with the elongate tubular sleeve 151, to the cylinder block 110. In this regard, the yoke-type damp 152 is received on the fuel injector 160, and extends radially outwardly an either side of the injector 160. The clamp 152 abuts against a fitting 163 of the injector where fuel lines connect. The clamp 152 is held against the fitting 163 by a collar 153 which is retained in position by one or more snap ring retainers (not seen) acting between the collar 153 and the fuel injector 160. The threaded fasteners 154 extend through the clamp 152 to internally-threaded drillings 125 formed in in the cylinder block. Washers are clamped between the heads of the fasteners 154 and an adjacent surface of the clamp 152.
As per
Referring again to
As may be understood with reference to
The O-ring 157, which may comprise an elastomeric ring, is received in the exterior circumferential groove 416 on the outer surface of the substantially cylindrical midsection 413 to seal against leakage of fluid from the coolant passage 130. The first washer 158, which may comprise a copper ring, is received on the substantially cylindrical end portion 155 of the elongate tubular sleeve 151 and is seated in the recess 115, clamped between a floor of the coolant passage 130 and the first substantially cylindrical end portion 420 to prevent leakage of gas from the bore 114 to the coolant passage 130. The second washer 159, which may comprise a copper ring, is disposed within the elongate tubular sleeve 151, girding the nozzle 161 of the fuel injector 160, and clamped between the fuel injector 160 and an interior end wall of the substantially cylindrical midsection 413 of the elongate tubular sleeve 151 to prevent leakage of gas from the bore 114 to the atmosphere.
Reducing or eliminating deformation of the cylinder bore of an opposed-piston engine that is attributable to mounting a fuel injector is accomplished by the invention, as follows. With respect to
Additionally, the seating configuration of the elongate tubular sleeve 151 allows for attachment of the fuel injector 160 to the cylinder block 110 while reducing, if not eliminating, adverse effects such as vibration modes in the fuel injector and fretting, and/or damage to any parts that operate a valve in the nozzle 161. In this regard, the elongate tubular sleeve 151 is anchored at the first of its ends to the cylinder block 110 by action of the spanner nut 156, and at the second of its ends by the threaded attachment of end 155. This prevents lengthwise and radial movement of the elongate tubular sleeve 151, thereby circumferentially buttressing the nozzle end of the fuel injector 160.
The fuel injector mounting assembly 150 can be implemented or installed onto a cylinder block 110 as follows. With reference to
As is evident from
Opposed-piston engines may have a parent bore cylinder block construction. Alternatively, opposed-piston engine cylinders may comprise cylinder liners received in tunnels formed in the cylinder block. The fuel injector mounting assembly of the invention is applicable to either construction. A parent bore cylinder block of an opposed-piston engine includes cylinders cast in the block with features defining coolant paths that ensure effective thermal management of the cylinders when the engine operates. Parent bore cylinder block constructions do not comprise cylinder liners or cylinder sleeves. In opposed-piston engines with a cylinder liner construction, the cylinder liner sidewall is effectively at least a portion of the cylinder wall referred to hereinabove and the inner surface of the cylinder liner is the bore surface. In each cylinder of an opposed-piston engine with a cylinder liner construction, the pistons reciprocate in the liner. The fuel injector mounting assembly described herein may be used with opposed-piston engines of either parent bore or cylinder liner construction. In opposed-piston engines with a cylinder liner construction, the second threads 408 on the substantially cylindrical end portion 155 of the elongate tubular sleeve 151 may threadedly engage a threaded injection aperture in the liner, thereby serving to retain the liner in the cylinder block.
In the foregoing specification, embodiments have been described with reference to numerous specific details that can vary from implementation to implementation. Certain adaptations and modifications of the described embodiments can be made. Other embodiments can be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This Project Agreement Holder (PAH) invention was made with U.S. Government support under Agreement No. W15KQN-14-9-1002 awarded by the U.S. Army Contracting Command-New Jersey (ACC-NJ) Contracting Activity to the National Advanced Mobility Consortium. The Government has certain rights in the invention.
