US2860617A - Enrichment device for fuel injection system - Google Patents

Description

Nov. 18, 1958 H. E. J. PRINGHAM 2,559,617

ENRICHMENT DEVICE FOR FUEL. INJECTION SYSTEM Filed June 21, 1957 INVENTOR.

ATTOPNEX United States PatcntOfifiCc 2,860,617 Patented Nov. 18, 1958 ENRICHMENT DEVICE FoR FUEL INJECTION SYSTEM Henry E. J. Pringlram, Grosse Pointe, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation 'of Delaware Application June 21, 1957, Serial No. 667,153

'11 Claims. (Cl. 123-119) is particularly adapted for use with a fuel injection systern of the type utilizing an atmospheric type nozzle such as shown in copending application Serial No. 608,893, Dolza, filed September 10, 1956.

In the fuel metering system of the previously noted copending application, fuel enrichment for starting and cold running operation is achieved by the use of a solenoid controlled mechanismwhich operates directly on the fuel metering valve so as to insure an increased fuel flow through the valve when fuel enrichment isnecessary. While such a system works satisfactorily, it represents a relatively expensive type control mechanism.

In the present device means is provided -wliich is adapted to coact with the atmospheric nozzles to provide fuel enrichment during cold starting and running. It is the purpose of the present device to take advantage of the manifold vacuum which is available at the atmospheric nozzle to provide a force whereby fuel enrichment is achieved.

It is a further object of the present invention to utilize a control mechanism which is adapted to restrictthe flow of atmospheric reference air to the atmospheric nozzle whereby manifold vacuum is adapted to increase the fuel flow through said nozzle and further which device is adapted to coact with the idle air system insuch a way as to increase the manifold vacuum force available to achieve the fuel enrichment noted.

The present fuel enrichment device has resulted in a considerably simplified system in that it is able to more effectively utilize components and conditions already existent in the system to achieve enrichment which was previously obtainable only with the addition of relatively costly components.

The details of the present invention as well as other objects and advantages are set forth in the description which follows.

In the drawing:

Figure 1 is a partially sectioned elevational view of a fuel system embodying the subject invention; and

Figure 2 is a fragmentary enlargement of Figure 1.

The fuel injection system functions in substantially the same manner as in the aforenoted copending application except as will be specifically described herein. In general, the fuel injection system comprises an air intake casing having air induction passage 12 formed therein. A venturi 14 is formed in said induction passage which also includes a throttle valve 16 disposed posteriorly of said venturi. A fuel metering mechanism is shown generally at 13 and is adapted to supply metered quantities of fuel to the individual cylinder fuel supply conduits 21). The quantity of fuel supplied to the fuel conduits is proportional to the mass of air flow through induction passage 12 as described in detail in the afore'noted co pending application.

Each fuel conduit 20 terminates in a nozzle 22 supported upon and partially projecting within the individual cylinder intake passages 24. Each fuel nozzle 22 includes a fuel inlet passage 26 which terminates in a fuel metering orifice 28. The fuel from metering orifice28 is projected in a stream across the enlarged chamber 30 where it is targeted through a larger orifice 32. The chamber 30 is adapted to communicate with a conduit 34 which communicates at its other end with the airintake casing 10 to provide reference air to the nozzle 22. The orifice 32 in the nozzle 22 has no metering effect on the fuel flow through the nozzle but does meter the quantity of air which is mixed with the fuel stream prior to its injection into the intake passage 24. As already noted, under normal operating conditions: the reference air in chamber 30 neutralizes the manifold vacuum force acting on the end of the nozzle 22 and thereby stabilizes the metered fuel flow.

It is to be noted that air conduit 34 communicates through passage 36 with the air induction passage 12 intermediate the throttle valve 16 and the venturi 14. In this way all air flowing to the cylinders of the engine passes through the venturi 14 and insures a maximum metering signal for the fuel metering control device 18.

To provide idle air bypass flow around throttle 16 a branch passage 40 leads from anterior throttle passage 36 and communicates withchamber 42 and posterior throttle opening 46. In this way a flow network is provided which is adapted to bypass air around a closed throttle 16 for idling operation.

A plunger valve mechanism 50 is adapted to be slidably mounted in the-intakecasing 10 so as to respectively control the air flow through nozzle reference air passage 36 as well as through the idle air bypass network. Plunger 50 includes a stern 52'having a pair of axially spaced lands 54 and 56 adapted to slidably support the plunger within an intake casing bore 58. Bore 58 intercepts atmospheric air passage 36 aswell as the idle air bypass chamber 42 and communicates with opening 46. The lower end 60 of land 54 is-adapted to coact with the atmospheric reference air passage 36 so as to variably restrictthe quantity of air flow therethrough in accordance with the axial position of said land relative to bore 58. Similarly land 56 is adapted to variably control the quantity of idle air flow bypassed around throttle 16' though passages 36, 40, chamber 42 and opening 46.

Stem 52 of plunger 50 projects through an openingin casing wall 62 and extends within a housing 64 projecting from the casing. A hollow piston member 66 is slidably disposed within housing 64 and loosely mounted about the enlarged end 68 of stem 52 so as to be capable of limited axial movement relative to said stem. A spring member 70 is disposed within the hollow piston 66 and biases against the enlarged end 68 of stem 52 urging the latter in a downwardly direction so as to seat against the closed end 72 of said piston. Another-spring 74 is disposed in housing 64 and seats against casing wall 62 so as to biasthe piston 66 and plunger 52 ina" downwardly or air flow restricting direction.

In order to control the movement of plunger50=in accordance with engine temperature, a temperature responsive means is provided and inthe present device consists of a bellows 76 disposed within housing"64 and adapted to engage the bottom of piston 66. Bellows 76 communicates through a capillary tube 78 with a temperature responsive bulb 80 suitably disposed within a portion of the engine, such as the cooling or exhaust system, which will accurately reflect the temperature of the engine. The bellows 76, tube 78 and bulb80 are filled with a suitable material which will expand on being heated to actuate the plunger 50 as will be discussed subsequently.

To achieve fuel enrichment when the engine is cold the plunger 50 is adapted to block the flow of air to nozzle 22 and also to block the flow of bypass air around throt tle 16, the latter at least when the engine is being cranked. In this way the manifold vacuum force in the cylinder intake passage 12 posteriorly of throttle 16 is maintained at a very high value since all passages which can bleed atmospheric air to the intake passage posteriorly of throttle 16 are blocked. Further, inasmuch as the atmospheric air cannot reach the atmospheric nozzle 22 through passage 36 manifold vacuum increases the pressure differential acting on the nozzle fuel thereby in creasing the flow of fuel through the nozzle and providing fuel enrichment.

With the engine cold the material within the temperature responsive mechanism 76, 78 and 80 will be unexpanded and spring ,74 will move piston 66 and through spring 70, plunger 50 so that the latter is in its lowermost position causing lands 54 and 56 respectively to block flow through passage 34 and idle air chamber 42. This will be the condition of the plunger when the engine is being cranked. Upon the engine starting, assuming the throttle 16 to be closed, the manifold vacuum in passage 12 posteriorly of the throttle will increase and act on the upper end of plunger land 56 moving the plunger upwardly against the force of spring 70, which is actually of a lesser rate than spring 74, the latter which retains the piston 66 in its original position. Manifold vacuum during the initial running of the engine in shifting the plunger upwardly will cause land 56 to open the idle air network permitting idle air to flow around the closed throttle 16. At the same time land 54 will be moved upwardly to permit a limited amount of air to flow through passage 34 to nozzle 22 reducing manifold vacuum at the nozzle and thereby leaning out the cold cranking mixture.

With the device as thus far described, it is apparent that upon sudden opening of the throttle 16 for acceleration purposes, the manifold vacuum adjacent land 56 will decrease and spring 74 will once again cause lands 54 and 56 to block the idle air passages 36, 40, 42 and 46 as well as the atmospheric reference air passage 34 to again increase the fuel air mixture for increased power.

As the engine temperature warms the temperature responsive bulb 80 will cause bellows 76 to expand and move the piston 66 upwardly against the force of spring 74 and at the same time causing the enlarged end 68 of plunger stem 52 to be abutted by the piston. Piston 66 thereafter will move plunger 50 upwardly until such time as the bottom end 60 of land 54 permits completely unrestricted fiow of air through passage 34 to atmospheric nozzle 22. At the same time the upper end 82 of land 54 is adapted to approach the shoulder 84 formed by bore 58 and chamber 42 and to thereby restrict the idle air flow around throttle 16. This latter restriction .of-

idle air flow is consistent with the reduced engine idling speed which is maintainable with a warm as opposed to a cold engine.

I claim:

1 A charge forming device for an internal combustion engine comprising an air induction passage, a venturi formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communicating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle with said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder, second passage means formed in said casing for bypassing air around said throttle, and valve means for restricting air flow through said first and second passage engine comprising an air induction passage, a venturiv formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communicating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle with said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder to negative the effect of manifold vacuum on nozzle fuel flow, second passage means formed in said casing for bypassing air around said throttle, and valve means for controlling air flow through said first and second passage means, means normally biasing said valve means to block air flow through said first and second passage means, temperature responsive means acting on said valve means to increase air flow through the first passage means as engine temperature increases.

3. A charge forming device for an internal combustion engine comprising an air induction passage, a venturi formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communicating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle with said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder, second passage means formed in said casing for bypassing air around said throttle, and valve means for restricting air flow through said first and second passage means whereby manifold vacuum will act on said nozzle to increase the flow of fuel therethrough, and means responsive to engine temperature and manifold vacuum for actuating said valve means.

4. A charge forming device for an internal combustion engine comprising an air induction passage, a venturi formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communicating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle with said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder to negative the effect of manifold vacuum on nozzle fuel flow, second passage means formed in said casing for bypassing air around said throttle, and valve means for controlling air flow through said first and second passage means, means normally biasing said valve means to block air flow through said first and second passage means, temperature responsive means acting on said valve means to increase air flow through the first passage means as engine temperature increases, and means responsive to manifold-vacuum for actuating said valve means to increase air flow through said first and second passage means independently of said temperature responsive means.

5. A charge forming device for an internal combustion engine comprising an air induction passage, a venturi formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communicating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle With said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder to negative the effect of manifold vacuum on nozzle fuel flow, second passage means formed in said casing for bypassing air around said throttle, and valve means for controlling air flow through said first and second passage means, means normally biasing said valve means to block air flow through said first and second passage means, temperature responsive means acting on said valve means to increase air flow through the first passage means and decrease flow through said second passage means as engine temperature increases.

6. A charge forming device as set forth in claim 1 in which said valve means comprises a common bore intersecting said first and second passage means, and a valve element slidably disposed in said bore, said element being adapted to coact with said first and second passage means to variably restrict the flow of air therethrough.

7. A charge forming device as set forth in claim 6 in which said valve element includes a stem having a pair of axially spaced lands formed thereon, said lands respectively coacting with said first and second passage means to control air flow therethrough.

8. A charge forming device as set forth in claim 7 in which one of said lands is adapted to control the flow of air through both said first and second passage means.

9. A charge forming device for an internal combustion engine comprising an air intake casing, an air induction passage formed in said casing, a venturi formed in said induction passage, a throttle valve rotatably mounted in said induction passage posteriorly of said venturi, a source of fuel under pressure, and conduit means for communieating said fuel source with the individual cylinders of the engine, means for metering the quantity of fuel flow through said conduit means in accordance with the mass of air flow through said venturi, each of said fuel conduit means terminating in a nozzle for supplying fuel to each cylinder of the engine, first passage means communicating said nozzle with said induction passage anteriorly of said throttle for supplying air to said fuel stream prior to its injection into said cylinder, second passage means formed in said casing for bypassing air around said throttle, a common bore intersecting said first and second passage means, a valve element slidably disposed in said bore and comprising a stem, a pair of axially spaced lands formed on said stem and respectively coacting with first and second passage means to control air flow therethrough, a housing associated with said casing, said stem extending within said housing, a hollow piston slidably disposed within the housing, said piston being loosely connected to said stem to permit relative axial movement therebetween, a first member biasing said piston and stem into engagement, a second member biasing said piston and stem in a direction causing said lands to restrict air flow through said first and second passage means, and engine temperature responsive means adapted to urge said valve stem in a direction at least initially increasing air flow through said first and second passage means.

10. A charge forming device as set forth in claim 9 in which said valve element communicates with said induction passage posteriorly of the throttle permitting manifold vacuum to move said element independently of said temperature responsive means by compressing said first biasing member.

11. A charge forming device as set forth in claim 9 in which one of said lands communicates with said induction passage permitting manifold vacuum to move said one land to increase air flow through said second passage means, said temperature responsive means being adapted to move the other of said lands to increase flow through said first passage means and decrease flow through said second passage means as engine temperature increases.

No references cited.

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