Pump apparatus for hydraulically powered fuel injection systems

Abstract

A pumping system for supplying high pressure actuation fluid to individual fuel injectors of an engine equipped with a hydraulically-actuated fuel injection system wherein the three major elements of the system, namely, the pump, the rail pressure control valve and the bleed-off sump or reservoir are physically separated and spaced from one another. The pump is annular, having a central opening through which the engine crankshaft passes. The crankshaft and pump wobble plate are rotationally coupled by opposing flats on each. The pump, rail pressure control valve and reservoir are mounted directly to the engine, receiving and discharging fluid through internal engine passageways, thereby eliminating the usual tubing, and fittings. The pump itself is compact and relatively short in the axial direction, leaving space for mounting such things as a cylindrical housing having belt grooves in its outer surface and a viscous damper on the crankshaft between the pump and the terminal crankshaft end.

Description

TECHNICAL FIELD

The present invention relates to engines having hydraulically-actuated fuel injection systems and, more specifically, to pumping systems for such engines.

BACKGROUND ART

Internal combustion engines equipped with a hydraulically-actuated fuel injection system (HEUI fuel system) employ an actuating pump to provide actuating fluid at elevated pressures to injectors, thus elevating the pressure of the fuel being injected into the engine. Control of the fuel injection pressure is achieved by controlling the pressure of the actuating fluid, hereinafter referred to for convenience simply as “oil.” Typically, control of the oil pressure is achieved by employing a fixed displacement pump to elevate the fluid pressure and regulating that pressure to lower levels by bleeding off unneeded flow volume through a rail pressure control valve (RPCV), past which the unneeded oil returns to a sump or reservoir.

In conventional HEUI systems, the pump, RPCV and reservoir are physically associated so as to form, in effect, a single unit which is mounted to the engine. Oil at low pressure is supplied from the engine to the pump through hydraulic tubing connected by suitable fitting to the engine and to the low pressure inlet of the pump. After elevation of pressure by the pump, the oil passes through the RPCV, and thence back to the reservoir or, through additional hydraulic tubing, to the high pressure manifold (rail).

Examples of hydraulically-actuated fuel injection systems are shown in U.S. Pat. No. 5,191,867 issued to Glassey, et al on Mar. 9, 1993, and U.S. Pat. No. 5,213,083 issued to Glassey on May 25, 1993; a variable-displacement pump for an HEUI fuel system is shown in U.S. Pat. No. 5,515,829 issued to Wear, et al on May 14, 1996, all of which are assigned to the assignee of the present invention. Pumps for HEUI fuel systems, as well as other rotary, engine-operated pumps, e.g., power steering pumps, typically have a pump shaft which is coupled to the engine crankshaft by appropriate connecting mechanism. Such a pump, mounted to a bracket and spaced forwardly of the engine and terminal end of the crankshaft, is shown in U.S. Pat. No. 3,927,954 issued to Walker on Dec. 23, 1975. This patent also shows a cylindrical housing with external belt grooves mounted upon the crankshaft between the engine and the pump and partially enclosing the pump.

The present invention is directed to solving various packaging and placement problems that occur when placing an HEUI system on a relatively small engine. Additionally, the invention is directed to providing a more cost effective and aesthetically improved design, and to overcoming one or more of the problems or concerns set forth above.

DISCLOSURE OF THE INVENTION

The present invention physically separates the three main components, namely the pump, the RPCV and the reservoir, of the HEUI system. The pump is mounted in encircling relation to the engine crankshaft for direct drive of the movable pump components which are keyed to the crankshaft. The low pressure inlet and high pressure outlet of the pump communicate directly with internal passages in the engine block, thus eliminating the need for hydraulic tubing between the pump and engine. Also, the inlet and outlet of the RPCV communicate directly with the engine block passages. Cold start oil volume in the rail is provided by mounting the reservoir at a slightly higher elevation than the rail instead of by a diaphragm mechanism in the pump. Further features are the provision of a hydrostatic thrust bearing to carry the thrust load of both sides of the wobble plate, and the mounting of other components, including a cylindrical housing with pulley grooves on its outer surface substantially enclosing the pump housing, on the crankshaft end extending through the pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of the components of the invention.

FIGS. 2 and 3 are perspective views of the pump unit of the invention, taken from opposites sides, and a portion of, the engine crankshaft.

FIG. 4 is a side elevational view in section on the line 4 — 4 of FIG. 2 .

BEST MODE FOR CARRYING OUT THE INVENTION

In the diagrammatic illustration of FIG. 1 , a fragment of an internal combustion engine is indicated generally by the dotted line 10 . Engine 10 includes the usual crankshaft 12 , having a portion rotatably driven by action of the pistons and connecting rods (not shown). Crankshaft 12 extends completely through pump 14 to a terminal end, indicated by reference numeral 12 ′, spaced outwardly from the pump. Pump 14 is secured to engine 10 by bolts 15 passing through openings 16 in flange 18 of pump housing 20 and into tapped openings in the engine block. Pump 14 receives low pressure oil from engine 10 through inlet port 22 and discharges high pressure oil through outlet port 24 . The engine block is so configured that inlet and outlet ports 22 and 24 , respectively, are in direct communication with corresponding ports on the block, thereby eliminating the need for the hydraulic tubing which normally provides such communication.

Referring now to FIG. 4 , low pressure oil fills the pump cavity surrounding plungers 25 , only one of which is seen, but a plurality of which are arranged about the central axis of pump 14 in conventional fashion. Oil is drawn into plungers 26 during the suction stroke through a groove in wobble plate 28 . The timing in degrees (e.g., 180) of the filling cycle is determined by a groove in wear plate 30 . Wobble plate 28 is rotated by crankshaft 12 by being keyed thereto or by means of mating flats 33 on the crankshaft and wobble plate, the latter being held in place by hydrostatic bearing 32 . For the remainder of each complete revolution, pump 14 is displacing high pressure oil into the high pressure annulus located in barrel 34 . Check valve 36 prevents leakage of high pressure oil back into the plungers during the suction stroke. Outlet port 24 is in direct communication with the high pressure annulus, thus allowing exit of the high pressure oil to engine 10 .

Referring again to FIG. 1 , high pressure oil travels through an internal passageway in the engine block to RPCV 38 . Internal passageways in the engine block are indicated by dash-dot lines denoted by reference numeral 40 . From RPCV 38 , oil passes to high pressure manifold or rail 42 with oil in excess of that required to maintain pressure in rail 42 at the desired level being bled off to reservoir 44 , the latter being mounted to engine 10 at a slightly higher level than rail 42 . Oil from rail 42 is applied to hydraulically powered fuel injectors 46 in the usual manner. Conventional pressure relief valve 48 is also connected to rail 42 . As also seen in FIG. 1 , between pump 14 and terminal end 12 ′, crankshaft 12 carries viscous damper 50 and cylindrical housing 52 , the latter having grooves in its outer surface for drive belts connected to the engine fan, alternator, air conditioning compressor, and/or other accessories. A major portion of pump 14 is surrounded by housing 52 and thus concealed from view.

INDUSTRIAL APPLICABILITY

The pump apparatus of the invention and its physical relation to the engine with which it is associated contribute to elimination of various packaging and placement problems common to mounting of HEIU pumps on small engines. The separation of the three major components of the pump system, i.e., the rail pressure control valve (RPCV), the pump reservoir, and the pump proper, allows for a short, compact pump mounted directly to the engine and driven directly by the crankshaft. All components are engine-mounted, with fluid inlets and outlets in direct communication with passageways in the engine block, thereby eliminating the need for any hydraulic tubing and associated connectors, fittings, etc. The axially short pump design permits the crankshaft to extend entirely through the pump housing and permit mounting thereon of additional driven components.

The RPCV is mounted on the engine near, and in fluid communication with the high pressure rail. The reservoir is mounted at a slightly higher level than the high pressure rail. The pump package is reduced by this separation since the need for cold start oil volume in the rail is held by elevation of the reservoir instead of a diaphragm mechanism in the pump.

This invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, the structure of which has been disclosed herein. However, it will also be understood by those skilled in the art to which this invention pertains that various changes or modifications may be made and equivalents may be substituted for elements of the invention without departing from the scope of the claims. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed in the specification and shown in the drawings as the best mode presently known by the inventors for carrying out this invention, nor confined to the details set forth in the preferred embodiment, but that the invention shall include all embodiments, modifications and changes as may come within the scope of the following claims:

Claims

1. A pump comprising:a housing that includes an attachment face with a plurality of fastener bores distributed to surround a drive shaft opening, an inlet opening and an outlet opening, wherein said drive shaft, said inlet opening and said outlet opening all open through said attachment face; a wobble plate rotatably mounted in said housing; and a plurality of parallelly disposed pistons positioned to reciprocate in said housing.

2. The pump of claim 1 wherein said plurality of fastener bores are distributed on a circle.

3. The pump of claim 1 wherein said attachment face lies in a plane.

4. A pump comprising:a housing that includes an attachment face with a plurality of fastener bores distributed to surround a drive shaft opening, an inlet opening and an outlet opening; a wobble plate rotatably mounted in said housing; a plurality of parallelly disposed pistons positioned to reciprocate in said housing; and said housing includes an annular flange that defines said fastener bores.

5. The pump of claim 1 wherein said wobble plate is separated from said housing by a fluid bearing.

6. An engine comprising:an engine housing defining an inlet internal passage and an outlet internal passage that open adjacent a crank shaft opening; a rotatable crank shaft partially positioned in said engine housing and including an end protruding through said crank shaft opening; and a pump surrounding a portion of said crank shaft and being attached to said engine housing and covering said inlet internal passage and said outlet internal passage.

7. The engine of claim 6 including a viscous damper attached to said crank shaft; andsaid pump being positioned between said viscous damper and said engine housing.

8. The engine of claim 6 including a drive belt support housing attached to said crank shaft;said pump being positioned between said drive belt support housing and said engine housing such that a majority of said pump is concealed; and said drive belt support housing being attached to said drive shaft between said damper and said pump.

9. The engine of claim 6 wherein said inlet internal passage is fluidly connected to a source of oil.

10. The engine of claim 6 including a wobble plate separated from a pump housing by a fluid bearing.

11. The engine of claim 10 including a plurality of pistons oriented parallel to said crank shaft.