WO1978000007A1

WO1978000007A1 - Direct injection fuel system

Info

Publication number: WO1978000007A1
Application number: PCT/US1978/000009
Authority: WO
Inventors: W M Pfeiffer
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-06-03
Filing date: 1978-06-01
Publication date: 1978-12-07
Anticipated expiration: 1979-12-03
Also published as: EP0007330A1

Abstract

Injection pressure generated by a suitable flow source (16) and a pressure-flow regulator (28) is carried by a common rail or manifold (20) to each injector valve of an engine. The valves (22) are of the closed differential needle, hydraulic-operated type, opening and closing for the injection period by virtue of hydraulic pressure imbalance and balance exerted on the effective piston areas of the valve needle. Balance conditions are controlled by fuel flow through ports and orifices (72, 74, 78, 102) of electric solenoid-operated sliding spool valves (52) by an engine-driven timer device (38, 40) which controls the start and end of the injection period. Controlled by-pass flow from the spool valves (52) may be collected by a low pressure manifold for return to the reservoir along with the overflow from a high pressure manifold (20).

Description

DIRECT FUEL INJECTION SYSTEM Technical Field

This invention relates to control of fuel injection in internal combustion engines, especially diesel. More particularly, it relates to a common-rail, closed dif¬ ferential needle, hydraulically operated injection valve system for fuel flow control.

Background Art U.S.- Patent No. 3.537,547, which I will refer to hereinafter as the AMBAC system, employs a common rail for operation of a diesel engine. Two pumps are required, one a high pressure pump for operating a type of hydraul¬ ic ram which acts on fuel supplied by the other, a low- pressure pump. Fluid from the high pressure pump is not injected into the engine. In the AMBAC system, the fuel is delivered to the injection valves at an injection pres¬ sure equal to the pressure in the common rail. The fuel delivery from the low pressure pump to the ram is init¬ ially mechanically timed from the engine, and initially metered by adjustment of the low pressure pump. Final metering of fuel into the engine is determined by con¬ trolling the length of the injection period, this being accomplished by the high pressure as it varies the en¬ gine speed. As speed and pressure increase; injection duration decreases the so-called torque control. These timing and metering adjustments are critical and high¬ ly complicated. They require use of an expensive pump test stand which can be handled only by special tech¬ nicians.

The prior art AMBAC solenoid is single wound and acts electrically in only one direction, return action being by spring. It can be used only on signal to be¬ gin an injection period, apparently playing no part in the duration. The single-wound solenoid operates through a diaphragm and push rod to open or unseat a ball-type check valve.

The prior art AMBAC system also employs an hydraul¬ ic imbalance-operated valve, the imbalance being created by the solenoid-operated check on the valves. It is used to control high pressure from a high pressure common rail system to operate a hydraulic ram which forces fuel from the fuel source system into the injection valve for injection into the engine. This valve in itself Is non-adjustable, and in itself cannot control final me¬ tering or duration, this function being performed by the pressure variations in the high pressure system.

Therefore, in view of the Inadequacies of the prior art AMBAC system as set out in aforesaid U.S. Patent No. 3,587,547, development of a simple, uncomplicated sys¬ tem for injecting diesel fuel to an engine at the right time and In the right quantity to obtain peak power without an undue amount of pollution represents a high¬ ly desirable result. Furthermore, there is a need for such an improved fuel injection system which does not require the expensive percussion-built injection pumps now in use and one which will permit manufacture and use of economic diesel passenger cars at substantial saving of fuel and improved pollution control.

Disclosure of the Invention After extended investigation I have developed just such an improved fuel injection system, particular¬ ly useful for diesel engines.

In its broader aspects my invention involves a single-pump fuel injection system In which the pump is of the positive displacement type capable of pro¬ viding sufficient cooling flow against the required rel¬ atively high pressure suitable for proper Injection. The pump of my system may be driven by an associated engine or by other means.

According to my invention, a common rail manifold connected to the pump discharge is also joined to a plurality of injection valve assemblies and pressur¬ ized to injection pressure by a pressure-regulating relief valve located at the manifold end opposite the inlet. Overflow from this valve may be piped back to a reservoir. Equal pressure is employed at each valve inlet, with minimum injection lag resulting.

The injection valves of the system of the invention are of the closed, differential needle, hydraulic-op¬ erated type, modified according to the invention so that they may be both opened and closed by hydraulic pres¬ sure. This modification makes the spring chamber func¬ tion as a pressure chamber. The injection valve spring helps close the valve at the end of injection. Adjust¬ ments may be made to obtain the proper rate of inject¬ ion and valve balance for best efficiency.

An important feature of my invention comprises electrically operated sliding spool valves which cause the mechanical motion of the injection valve needle by controlling the hydraulic pressure balance conditions exerted on the valve needle. Each of the spool valves of the invention consists of two sections, the spool having three lands and two undercut sections. One sec¬ tion controls a by-pass flow from the spring chamber of the injection valve by opening or closing a port leading to a by-pass manifold. The other section re¬ ceives injection pressure from the high pressure system and passes it through a combination port-orifice into the injection valve spring chamber. In the non-inject position, the by-pass port of the first section remains open, permitting flow from the spring chamber, and the port-orifice is in the orifice condition by means of the spool land forming a restriction. Flow through this orifice causes a pressure drop in the spring chamber and allows injection pressure on the valve needle to open the valve for injection.

One advantage of my invention is the possibility of using a common low pressure by-pass manifold to re¬ ceive fuel by-passed by the spool valve and connect with the overflow return line from the high-pressure mani¬ fold. Double-wound solenoids may be employed to actuate the spool valve spools in both directions. Solenoid plungers may be used as extensions of the valve spools and equipped so as to hold the spools In their shifted positions. Also, by means of a travel adjustment, spool travel may be set, acting as an orifice size adjustment and rate of injection adjustment. The two oppositely wound solenoid coils may be terminated at three exter¬ ior connectors in such a way as to provide positive bi¬ directional valve spool motions as each coil may be commonly connected to one of three terminals, and this terminal connected by wiring to a suitable electric power source through an on-off control switch. The other two ends of the two coils may be separately connected to the other two terminals, and these terminals connect¬ ed by wiring to proper respective terminals on a timer.

According to my invention the preferred timer de¬ vice is mechanically driven by and timed to the engine of my injection system and includes two sets of contacts mounted on suitable bases, with one set to control start of injection and the other to control the end of injection. Each set contains a separate contact for each Injection valve of the engine, and these contacts are connected by wiring to corresponding terminals on the aforesaid solenoids. Included may be a rotating con¬ tact or brush for use in energizing the solenoids in se¬ quence.

One set of contacts amy be made variable in relation to the other set so that the length of the injection period may be varied, thereby achieving control of me¬ tering and engine speed.

Normal shutdown may be accomplished by an on/off switch.

Emergency shutdown may be accomplished by a manual control on a pressure relief valve to dump off the in¬ jection pressure in the high pressure manifold.

According to my invention I prefer to use a var¬ iable speed type governor to throttle the engine. This governor employs a fulcrum lever to articulate a mov¬ able contact disc in a timer. The governor is thus en¬ abled to read the engine speed and automatically set the fuel delivery for the particular engine speed read. This, especially when combined with my system of meter¬ ing, which is accomplished by electrical control of duration of injection, permits the air-fuel ratio to be strictly and easily adjusted on the engine inframe at any and all engine RPM points by matching the fuel delivery curve to a volumetric efficiency curve, there¬ by insuring peak torque with a minimum of pollutants and substantially no smoke. signal source 118 Includes as basic components there¬ of a rotatable contact plate 120, for injection dura¬ tion control, a grounding bush rotor 122 and a stat¬ ionery contact plate 124 timed to the engine.

In the timer-governor of Fig 5 the setting of throttle 108 controls the operation of the governor. The brushes complete the circuit to open the coil in the solenoids such as the one depicted in Figs 2 and 3. One set of double windings (64 of Figs 2 and 3) is to pull the valve into position. The stationary contact plate 124, which is timed to the engine via the cam¬ shaft gives a constant beginning of injection by pull¬ ing the valve to open the port or a constant ending by pushing the valve to close the port. The other plate 120, rotatable, lags behind. When the amount of fuel needed by the engine is injected as dictated by the gov¬ ernor throttle, a second brush contacts the other plate and de-energizes the opposing set of windings, causing the solenoid to go in the other direction. Contact plates 120 and 124 are adjustable at the initial timing.

It can be readily seen from the foregoing descrip¬ tion that my fuel injection system, by providing control of pressure by a spool valve-solenoid arrangement, elim¬ inates a leak-off chamber and permits improved fuel in¬ jection or delivery and obtains optimum efficiency by better control of fuel-air ratio. Constant high pressure rail and manifold system such as depicted in Fig 1 which employs a single high pressure pump for both pressure and fuel delivery. The spool valve-solenoid arrangement such as shown in Fig 4 controls the pressure so that the high pressure source is tapped off, with the spool valve, which is electrically controlled by the solenoid, going down as pressure comes in via lower lines 98 and 78 and then back through by-pass inlet port 76 and line 96 into chamber 86 as by-pass outlet port 74 connected to by¬ pass manifold 32 of Fig 1 is closed. By-pass outlet port 74 is opened when the orifice formed near 80 becomes o- pen as the spool valves turn and go up, thus providing an exit for pressure in the injection valve, as In Fig 4, thereby dropping the pressure therein so that the constant high pressure opens the valve and injects fuel to the engine exactly as needed in a controlled manner as the needle valve 94 moves.

Following are several features or advantages of the fuel injection system of the invention.

1. A single high pressure pump or fuel to be in¬ jected and an injection pressure which is set and con¬ trolled by a compound pressure-regulating valve where¬ by excess may be spilled back to a tank. No adjustment of the pump is necessary, the injection pressure being adjustable by the regulatory valves.

2. An impulse source to begin and end injections, the duration being variable by a movable set of contacts. Beginning and ending of injection may be either constant- variable or vice-versa.

3. Hail pressure is dictated by setting a compound pressure relief valve. 4. A double wound solenoid enables positive elec¬ trical action in either of both directions upon sig¬ nals for a definite beginning and ending of the injec¬ tion period. It is mechanically connected to and op¬ erates an associated spool valve.

5. An electrically operated solenoid valve with two sections or chambers. One section starts or stops fuel flow into a by-pass manifold, and the second sec¬ tion restricts or opens an orifice, creating a pressure drop or pressure balance on an Injection valve needle, thereby opening and closing it for injection. Because the valve spool travel is adjustable, it regulates the size of the orifice, the rate of pressure drop, the valve opening and the rate of injection.

6. Capability of obtaining an optimum fuel air ratio (20:1 running) for a maximum 90% volume efficiency. Since conventional intake manifolds have no butterfly controls, the amount of air in the engine cuts back as the RPM increases. Since the fuel curve increases as the air curve increases, on accelerating, the engine fuel delivery must be cut back to between the torque peak and the hp peak. This can be done according to my invention by use of the nozzle valve being operated di¬ rectly hydraulically.

While the invention has been described in terms of preferred embodiments, the claims appended hereto are intended to encompass all embodiments which fall with¬ in the spirit of the invention.

Claims

Having thus described my invention and certain pre¬ ferred embodiments thereof, I claim:

1. In a fuel injection system an electrically operated spool valve device comprising in cooperative association a spool valve, a double-wound solenoid adapted to oper¬ ate said valve, an orifice adapted to be opened when the spool valve turns and moves upward, a by-pass port a- dapted to be opened when the spool valve turns and moves up, and entering and exiting channels adapted to be con¬ nected to an injection valve.

2. The spool valve device of Claim 1 in cooperative as¬ sociation with at least one additional spool valve de¬ vice of the same structure in common manifold alignment.

3. The spool valve device of Claim 2 in cooperative as¬ sociation with a governor, timer, pressure pump and in¬ jection valve.

4. In a fuel injection system an Injection valve com¬ prising a high pressure inlet, a high-low pressure cham¬ ber, a nozzle body, a wall, an injection pressure cham¬ ber, a needle valve positioned at the end of said in¬ jection valve opposite said high pressure inlet, and lines adapted for releasing pressure from said inject¬ ion valve and returning pressure thereto.

5. The injection valve of Claim 4 in cooperative as¬ sociation with a solenoid-operated spool valve where¬ by the pressure In said injection valve may be controlled.

6. The injection valve of Claim 5 wherein the solenoid- operated spool valve comprises the spool valve device of Claim 1.

7. The injection valve of Claim 4 in cooperative assoc¬ iation with a governor, timer, pressure pump, common rail manifold and solenoid-operated spool valves and fuel source.

8. A direct injection fuel system comprising in cooper¬ ative association a governor-timer, a single high pres¬ sure pump adapted to supply and distribute fuel at a controlled pressure and amount to an engine, and a com¬ mon rail manifold in association with a plurality of injection valves connected to corresponding solenoid- operated spool valves adapted to regulate the pressure in said injection valves.

9. The system of Claim 8 wherein the governor-timer comprises a governor comprising a throttle, fulcrum lever, peak fuel adjuster, air-fuel ratio adjuster, an RPM reader, and, in association with said governor, a timer comprising a rotatable contact plate for injection duration control, a grounding brush rotor and a sta¬ tionary contact plate adapted to be timed to an engine.

10. A process for controlling fuel-air ratio and pressure injection of fuel into an internal combustion engine which comprises generating injection pressure by a high pressure pump and a pressure-flow regulator valve, carry¬ ing same along with fuel by a common rail manifold to a plurality of needle valves in hydraulically operated in¬ jection valves, controlling fuel flow in said valves through pressure ports and orifices to and from a corres¬ ponding plurality of solenoid-operated sliding spool valves and employing a governor-timer to control, a- long with said spool valves, the starting and ending of the injection of fuel into said internal combustion en¬ gine.

Having thus described my invention and certain preferred embodiments thereof, I claim:

1. In a fuel injection system an electrically operated spool valve device comprising in cooperative association a reciprocating action spool valve operated by a double-wound solenoid and an Injection valve having two matching passages therebetween, apressure differential orifice created when, in operation, the spool moves from a non-inject to an inject position, said orifice adapted to be created when the spool valve moves upward, a by-pass port adapted to be opened when the spool valve moves upward, and entering and exiting channels.

2. The spool valve device of Claim 1 in cooperative as¬ sociation with at least one additional spool valve device of the same structure in common manifold alignment.

3. The spool valve device of Claim 2 in in cooperative as¬ sociation with a governor, timer, pressure pump and injection valve.

4. In a fuel injection system an injection valve com¬ prising a high pressure inlet, a high-low pressure chamber, a nozzle body, a wall, an injection pressure chamber, a needle valve positioned at the end of said injection valve opposite said high pressure inlet, and interconnecting passages be¬ tween said injection valve and a reciprocating action spool valve operated by a double-wound solenoid, said passages adapted for releasing pressure from said injection valve and returning pressure thereto.

5. The injection valve of Clain 4 in cooperative as¬ sociation with a solenoid-operated spool valve whereby the pressure in said injection valve may be controlled. 6. The injection valve of Claim 5 wherein the solenoid- operated spool valve comprises the spool valve device of Claim 1.

7. The injection valve of Claim 4 in cooperative as¬ sociation with a governor, timer, pressure pump, common rail manifold and solenoid-operated spool valves and fuel .source.

8. A direct injection fuel system comprising in cooper¬ ative association a speed governor which comprises a throttle and a fuel adjuster, a timer-made up of a rotatable contact plate for injection duration control, a grounding brush rotor and a stationary contact plate adapted to be timed to an engine, a single high pressure pump, adapted to supply and distribute fuel at a controlled pressure and amount to an engine, and a common rail manifold in association with a plurality of in¬ jection valves connected to corresponding solenoid-operated spool valves adapted to regulate the pressure in said injection valves.

10. A process for controlling fuel-air ratio and pres¬ sure injection of fuel into an internal-combustion engine which comprises generating injection pressure by a high pres¬ sure pump and a pressure-flow regulator valve, carrying same along with a fuel by a common rail manifold to a plurality of needle valves in hydraulically operated injection valves, con¬ trolling fuel flow in said valves by means of a plurality of solenoid-operated sliding spool valves having pressure dif¬ ferential orifices created when the spools move from a non- inject to an inject position and employing a governor-timer to control, along with said spool valves, the starting and ending of the injection of fuel into said Internal combustion engine .

STATEMENT UNDER ARTICLE 19

STATEMENT EXPLAINING THE AMENDMENT AND DRAWING ATTENTION TO THE DIFFERENNCE BETWEEN THE REPLACED SHEETS AND THE REPLACEMENT SHEETS

Claim 1 of replacement sheet 12 has been amended to make clear that

(1) Applicant's spool valve is a reciprocating-action valve 24 operated by a double-wound solenoid 26, (2) The two principal parts (of which there may be a series) of Applicant's feed value system are the spool valve

24 and the injection valve 22, which have two matching pas¬ sages 76, 96 and 78, 98 between them, as depicted in Fig. 4 in detail, and

(3) The orifice near 80 Is a pressure-differential ori¬ fice created when the spool moves from a non-inject to an inject position (sheet 10, lines 1-15)

In Claim 4 of replacement sheet 12 it is now specified, as with respect to Claim 1, that Applicant's valve 24 is a double-wound solenoid 26 and that there are interconnecting passages 76, 96 and 78,98 between the spool valve 24 and the injection valve 22 (sheet 10, lines 1-15).

On replacement sheet 13 Claim 9 has been combined with Claim 8 to specify that Applicant's speed governor 106 (sheet 8, fourth to last line) is made up basically of a throttle 108 and a fuel adjuster 114 and that his timer 118 comprises a rotatable contact plate 120 for injection duration control (line 2, sheet 9), a grounding brush rotor 122 (line 3, sheet 9) and stationary contact plate 124 (line 4, sheet 9) adapted to be timed to an engine.

Claim 10 bridging sheets 13 and 14 has been amended on replacements sheets 13 and 14 to specify how Applicant's solenoid-operated sliding spool valves have a pressure dif¬ ferential orifice created, as. explained hereinabove and in Applicant's specification, when the spool moves from a non- inject to an inject position (lines 1-15 - sheet 10). Please note in this respect Applicant's remarks hereinabove in con¬ nection with the changes made in Claim 1 on replacement sheet 12.