CA1049845A - Fuel pumping apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A fuel pumping apparatus for supplying fuel to an internal combustion engine includes a plunger reciprocable within a bore, pump means for supplying fuel to the bore to urge the plun-ger in an outward direction, a cam for impating inward movement to the plunger to displace fuel form the bore through an outlet and stop means for determining the maximum outward movement of the plunger. The stop means includes a stop member which can be positioned by first and second devices one of which determines whether excess fuel will be supplied for starting purposes and the other of which determines the normal maximum amount of fuel for operation of the engine once it has started. The engine is super-charged and the device includes a pressure responsive diaphragm which is subject to the outlet pressure of the supercharger. The diaphragm effects movement of a member from a first position to a second position and the member is operatively connected to a further member which determines the setting of said stop means. In the second position of the member an increased quantity of fuel is supplied to the bore for subsequent delivery to the engine when the supercharger of the engine is in operation.

Description

This invention relates to fuel pumping apparatus for supplying fuel to a supercharged internal combustion engine and of the kind comprising a plunger reciprocable with a bore, pump means for supplying fuel under pressure to said bore to urge the plunger in an outward direction, control means for determining the quantity of fuel supp-lied to said bore by said pump means, a cam for imparting . . ~ .
inward movement to the plunger to displace fuel from said bore through an outlet and stop means for determining the ~; 10 maximum outward movement of the plunger irrespective of the setting of said control means.

When such apparatus is utili~ed to supply fuel to a supercharged engine it is necessary to provide at least two levels of maximum fuel to ensure that under all condi-tions of operation the level of smoke in the exhaust of the engine is no more than is allowed by the various regulations , in force. With a supercharged engine and particularly when '~ the supercharger is of the type which includes a turbine driven by the exhaust of the engine, the degree of super-charging at low engine speeds is such that the engine can for all practical purposes be regarded as a "naturally asp-- irated" engine. -.
As the engine speed increases the supercharger bec- ~;
omes effective and a greater mass of air is delivered to the engine combustion spaces. The level of maximum fue~l can there-fore be increased as the supercharger becomes more effective.

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104~845 It is however necessary to ensure that the apparatus can provide an excess of fuel for starting purposes the level of excess fuel usually being greater than the level when the supercharger is providing the maximum pressure.

The object of the invention is to provide an apparatus of the kind specified which is capable of providing two levels of maximum fuel in addition to excess fuel for starting purposes.

According to the invention in an apparatus of the kind specified said stop means comprises a stop member movable in a direction at right angles to the axis of movement of the plunger, first and second members, each of said first and second members being independantly adjustable to determine the position of said stop member, means coupled to one of said members for positioning said one member so that an excess of fuel will be supplied by the apparatus for starting purposes, and air pressure responsive means coupled to the other of said members, said air pressure responsive means in use, being subjected to the pressure of air developed by `~
the supercharger of the engine whereby the other of said members will be positioned to provide at least two levels of maximum fuel.

According to a further feature of the invention said other member is movable in said direction and its movement is impar~ed through said one member to said stop member.
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In the accompanying drawings:-104~845 Figure 1 is a sectional side elevation of one example of an apparatus in accordance with the invention, Figure 2 is a section at one axial position of the apparatus, Figure 3 is a side view showing two co-operating parts of the apparatus, : Figure 4 is a perspective of two further parts of the apparatus, Figure 5 is a view similar to Figure 2 with the section : 10 taken at another axial position and, .~ .
Figure 6 is a view showing to an enlarged scale, a modiication of part of the apparatus of Figure 2.

Referring to the drawings the apparatus comprises a housing 110 in which is located a rotary cylindrical distributor :.
member 111 which is coupled to a drive shaft 112 which extends : from the body part and is adapted to be driven in time relationship with a supercharged engine with which the apparatus is associated.

Formed in the distributor member is a transversely extending bore 113 in which is mounted a pair of reciprocable pumping plunger 114. Communicating with the bore 113 and extending longitudinally within the distributor member is a passage 115 which at one point communicates with a radially disposed delivery passage ~not shown) which is adapted to ' ' ~

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register in turn as the distributor member rotates, with a plurality of outlet ports 116 formed in the housing. ~he outlet ports in use are connected to fuel injection nozzles disposed to direct fuel into the combustion spaces of the associated engine.

At another point the passage 115 communicates with radially disposed inlet passages 117 which are able to register in turn as the distributor member rotates, with an inlet port 118 formed in the housing. The inlet port 118 communicates with a supply passage 119 by way of an angularly adjustable throttle member 120 ., .
and when the inlet port communicates with the passage 117 fuel will flow from the supply passage 119 to the bore 113. The amount of fuel which can flow when such communication is established, depends on the setting of the throttle member 120. In known manner the setting of the throttle member 120 is controlled by a governor mechanism which includes a plurality of weights 121 movable outwardly to decrease the amount of fuel supplied, the weights moving in opposition to a governor spring (not shown) the force exerted by which can be adjusted by means of an operator adjustable member tnot shown).
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The supply passage 119 communicates with the outlet of a feed pump (not shown) which draws fuel from an inlet 122 and the outlet pressure of the feed pump is controlled in known manner, by means of a valve (not shown).

At their outer ends the plungers 114 contact shoes 123 which support rollers 724 respectively. The rollers 124 engage with the internal peripheral surface of a cam ring 125 which is angularly adjustable within the housing. The cam ring has on its internal peripheral surface, a plurality of pairs of cam lobes. The rollers 124 and the shoes 123 rotate with the distributor member 111 and as the rollers engage the cam lobes inward movement will be imparted to the plungers 114. During this movement fuel is displaced from the bore 113 and flows by way of the passage 115, to one of the outlet ports 116. When the rollers 124 move over the cam lobes the plungers 114 can move outwardly under the action of fuel which is supplied by way of the inlet port 118, the fuel flowing to the passage 115 by way of one of the inlet passages 117.

The angular setting of the cam ring 125 is adjustable in known manner, by means of a fluid pressure operable piston 126 which is contained within a housing 127, the piston being connected by means of a peg 128 to the cam ring. Fuel under pressure is applied to the piston 126 by way of a passage 129 which communicates with the passage 119.

' In order to control the quantity of smoke in the exhaust system of the engine it is necessary to limit the maximum amount of fuel which can be supplied by the apparatus under normal operation but it is also necessary to aIlow the apparatus to provide an additional or excess quantity of fuel to enable the associated engine to be started particularly when it is cold.
Moreover, since the engine is a supercharged engine the amount of fuel which can be supplied to the engine depends upon the pressure of air delivered to the engine by the supercharger. S4p means is therefore provided to control the permitted outward movement of the rollers lZ4 and thereby the shoes 123 and the plungers 114.

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The end portions of the rollers 124 ars tapered and ~.ount~d on opposite sides of the rollers ar~ a pair of stop rings 130.
The stop rings are positioned outwardly of the rollcrs and arc shaped for en~a~ement with tho end portions of the rollers. As seen in ~igure l of thc drawings, the ri~ht-hand stop rlng is fixed within the housing however7 thc left-hand stop ring is set into an annular member 131. The annular member 131 is angularly adjustable as will be described.

The face of the annular member 131 remote from the rollers is engaged by the end face of a ring member 133 and this is secured against angular movement within the housing by means of a stop 132 engageable within a slot defined within the ring member The peripheral surface of the ring member 133 is provided ~ith a screw thread which is in engagement with a complimentary screw thread formed on the internal periphery of a further ring member 134 and the outer peripheral surface of the ~urther ring member is prov;ded with gear teeth engaged by a worm adjustor 135. The angular setting of the adjustor 135 may be determined from exterior of the body part in a manner to be described, ~s the adjustor 135 is rotated the further ring member ].34 will partake Or angular movement and by virtue of the screw threaded connection between the ring members 133 and 134, the ring member 133 will move axially. Such axial movement will be imparted to the annular member 131 and by this arrangement the amount by which the ~ollers 124 can move outwardly can be determined. ~or practical purposes the an~ular setting of the adjustor 135 will be preset when the pump is assembled but it may be reset as and when required.

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~049~345 m e adjustor 135 is also axially movable and such morement also has the effect of causing angular movement of the ring member 134 and therefore axial movement of the ring member 133. As shown in Figure 5 the adjustor 135 has connected thereto a cylindrical rod 150 which is guided for axial movement in a bore formed in an angularly adjustable body 151 mounted in a recess in the housing 110. The end of the rod remote from the adjustor extends into a cavity defined in the body 151 and is also screw threaded.

Slidable within the cavity is a plug member 152 which is in adjustable screw thread engagement with the rod 150 and the plug member is biased in the direction out of the cavity by means of a coiled compression spring 153. The extent of movement of the plug member against the action of the spring 153 is limited by a flange formed on the plug member and which engages with the end face of the body 151. The plug member is engaged by a flexible diaphragm 154 which forms an end wall of a chamber 155 to which air under pressure can be admitted through an inlet 156 from the inlet manifold of the engine. m e diaphragm in fact forms a division wall between a pair of cup shaped parts 157 and 158, the part 158 being secured to the body and the part 157 carrying the inlet.

The body 151 is retained in the housing 110 by means of a hinged plate 159 which locates within a circumferential recess in the body and interposed between a step on the body and a washer bearing on the plate is a coiled compression spring which acts to resist angular movement of the body within the housing. When adjustment is completed as will be described, the body is secured ... .
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against rotation by means of a security wire. The end of the body 151 is provided with a pair of diametrically disposed slots the walls of which engage flats formed on the adjustor 135 and in this manner angular movement of the body will impart angular movement to the adjustor 135. When the engine is at rest the spring 153 will urge the plug 152 together with the rod 150 and adjustor 135 upwardly to the position in which the adjustor engages the body. The body is then moved angulaxly to obtain a maximum fuel setting which is appropriate for the operating range of the engine in which the output pressure of the supercharger is such that the engine can be regarded as being "naturally aspirated."

In use when air under pressure is supplied to the chamber 155 the extent of movement of the adjustor will be determined by the abutment of the flange on the plug with the body. The range of movement and therefore the increase in the maximum amount of fuel, is adjusted by altering the amount by which the rod 150 is screwed into the plug. once this setting has been made the threads can be locked together with a proprietory locking compound.
The pressure of air required to effect movement of the adjustor is determined by the pre-load of the spring 153.

In order to provide an excess of fuel for staring purposes it is clearly necessary to allow further separation of the stop rings 130. For this purpose the ring member 133 is provided'with ,, a plurality of concave recesses 136, in its face presented to the annular member 131. One such recess is seen in Figure 3.
Moreover, the annular member 131 is provided with complimentary :~ ~,. ' ~ . ' . ' -~ ~ o 104~8~S
projecti~n~ 137 ~d during norm~l operation of the apparatus the projections 137 engage the end face of the ring memb~r 133 ~s is shown ln ~igure 3. When an excess of fuel i5 required for startin8 purposes the annu].~r me!nber 131 is moved angularly so as to bring the projections 137 into register with the recesses 136. Wh.en this occurs the main body portions of ths annular member and the ring ' member can move closer together thereby allowing ~ncre2sed separation of-tho stop rings 130 so that the plungers 124 can move an additional amount in the outward direction.

Movement of the annular member 131 is ~cilieved by means Or a second adjustment means generally indicated at 136a in E`igure Z. The second adjustment means comprise-s a piston 137 which is ,slidable within a cylinder 138. The piston is connected by mean~
of a pin 139A to the annular member and is biased by means of a ' ,spring 139 contained in one end of the cylinder 138. At the oth~r end of the cylinder 138 is an angularly adjustable membor 140 wllich contains a fuel supply passage 141 and which is connected to the fuel supply passage 119. A valve 142 is provided to control the ~low of fuel into the cylinder 13~. Moreover, the angularly movable member 140 and the piston 137 are provided with inter-engageable members whereby movement of the piston 137 under the :
action of its spring 13g is prevented until the member 140 is moved angularly. In the particular example the member 140 is provided with a tongue 143 engageable with a recess 144 formèd in the piqton and the member 140 is biased by means of a spring 145 to a position in which the tongue 143 is out of alig~nent with .
the reces~ 144. . :
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, When an ~xcess of fuel is required for ~arting purposes the melnber 140 is moved angularly against the action of the spring 1~5 to bring the tongue 143 into register with the recess 144 and when ~his occurs the piston 137 moves ~der the action of the spring 139 thereby moving the annular mem ber 131 angularly and bringing the projections 137 into reg-ister with the recesses 136, l~'hen this occurs the annular member 131 will be forced in an axi.al direction by the force actirg on the rollers 124 and deve~p~d by the fuel pressure acting on the plungers 114. In this manner an excess of fuel is supplied for starting purposes.

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The action of the valve 142 is to delay the application of fuel pressure to the piston 137 until the speed of the associated engine has built up. ~nce the valve 142 is lifted ~rom its seating then fuel pressure acts on the piston and the latter is moved to the position shown in Figure 2. In this ,~ ~
position the normal rnaximum amount of fuel is supplied to the . , .
engine. The valve 142 comprises a ball which is urged into :.
contact with a seating defined on the angularly adjustable member 140, The ball is loaded by means of a coiled compression ~:~
spring positioned between the ball and the piston 137. By this :~
arrangement the initial pressure required to open the valve is higher than the pressure at which it will close because once the piston has moved then the force exerted by the spring which loads the ball is reduced. The practical effect of this arrange-ment is that excess fuel will be supplied by the apparatus until the engine attains a speed greater than its normal idling speed but even ir the tongue and groo~ are maintained in alignment ..... -- r-:~
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excess fuel will not be obtained until the engine spe~d - has dropped well below its normal idling speed.

It wil7 be noted that when the piston 137 is iIl the normal maximum fllel position then it is impossible to obtain excess fuel by rotating the angularly adjustab1e member 140.
/To enable angular adjustment of the member 140 to be effected, it is provided with a plate 146 which carries an offset pin 147 which can be connected to a driver operable linkage (not shown), .
In some instances it is desirable to ensure that the timing of delivery of fùel to the engine is retarded during the delivery of the excess of fuel. This effect can be obtained by causing the piston 137 to act as a valve, As sho~m in ~igure 2 a passage 149 is provided which comml~icates with the outlet 119 of the feed pump. In addition a further passage 148 is provi~ed which when it is desired to retard the injection of fuel~ acts to convey fuel under pressure to the passage 129~ the direct connection o~ the passage 129 with the outlet 119 of the feed pump being broken, The passage 148 communicates wi~h the cylinder 138 at a position such that it will be covered by the piston 137 when the piston is in the position Ruch that excess fuel is supplied~ the passage being uneovered when the piston moves to its normal fuel position.
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With the arrangements described the maximum amount of fuel which can be supplied by the apparatus has at least two levels for normal operation of the engine and in addition excess ~-fuel can be obtained for startingr purposesO

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104~i845 It will be noted that the ball forming the valve 142 isloaded by a spring into contact with its seatln~. A~ a reRult the movement of the pis'on 137 when exces~ fuel '~ selected, will be 810w ~ince the fuel displaced by the piston can only escape by leakage. This can in praetical terms be a nuisance becauss if for example, the engine is started ~rom cold and runs up to a speed at which the ~upply of exces~ fuel cea~es and then stalls, there is a delay before exceos fuel is again obtained.

; This difficulty can be o~ercome by the modified cons-truction shown in Figure 6. In Figure 6 the piston 1~0 replaces the piston 137 and the member 161 and the member 140. The member 161 is -~ provided with a ton~ue not shown which can locate in a groove in the pi~ton, the tongue and groove being engaged in the position Or the parts shown in Figure 6. The valve however i8 different and it is a normally open val~e with a ball 162 biased away ~rom its seating ~-by a light spring, the extent of movement being limited by a stop plate ha~ing a non-circular aperture. Moreover, the piston 160 i~ provided with an abutment 163 which engagee w~th the ball when the piston i~ in the posltion corre3ponding to excess ~uel, to hold the ball in contact with the seating.
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In use~ with the ball in thè cto~ed po~ition the fuel pres~ure acts only upon the ball and therefore the pre~sure must rise to a considerable value before the force exerted on the ball is ~u~ficient to li~t the ball from the seating against the action o~
the spring biasing the piPton. ~nce the ballhae lifted then the ~uel preesure ac~s upon the pieton and the lat~er 1B mo~ed its maximum extent and w~ll remain in thi~ position even if the engine ~peed ~all~ to ~ling speed.

' 1049~145 When the engine stops tlle piston can return quickly to the position shown providing the tongue is aligned with the groove~
because the ball is held away from its seati.ng, Thus excess fuel can be obtained quickly. As the valve is moved into the sea~in~
the movement of the piston could be restricted however, this is overcome by arranging for t.he piston to open a le~kage path ~rom the space between the piston and the member 161. As shown in Figure 6 the leakage path comprises a groove 164 extending towards the head of the piston and which communicates with a port 165 in the wall of the cylinder containing the piston as the ball is moved onto its seating. The port 165 communicates with the aforesaid space, ., ~ ' ' ,., :
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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A fuel pumping apparatus for supplying fuel to a supercharged internal combustion engine and comprising a plunger reciprocable with a bore, pump means for supplying fuel under pressure to said bore to urge the plunger in an outward direction, control means for determining the quantity of fuel supplied to said bore by said pump means, a cam for imparting inward movement to the plunger to displace fuel from said bore through an outlet and stop means for determining the maximum outward movement of the plunger irrespective of the setting of said control means, said stop means comprising a stop member movable in a direction at right angles to the axis of movement of the plunger, first and second members, each of said first and second members being independently adjustable to deter-mine the position of said stop member, means coupled to one of said members for positioning said one member so that an excess of fuel will be supplied by the apparatus for starting purposes, and air pressure responsive means coupled to the other of said members, said air pressure responsive means in use, being subjected to the pressure of air developed by the supercharger of the engine whereby the other of said members will be positioned to provide at least two levels of maximum fuel.

2. An apparatus according to claim 1 in which said other member is of annular form and is formed with a peripheral thread engaged by a further annular member, means being provided to prevent angular movement of said other member whilst allowing axial movement thereof, said further annular member being movable angularly by said air pressure responsive means to effect axial movement of said other member.

3. An apparatus according to claim 2 in which said further annular member is provided with teeth on its outer periphery the apparatus also including a worm wheel engageable with said teeth, said air pressure responsive means being operatively connected to said worm wheel whereby variation in the air pressure will result in axial movement of the worm wheel and angular movement of said further member, said air pressure responsive means being capable of moving said worm wheel between first and second positions corresponding to the maximum fuel setting for engine operation when the engine can be regarded as being naturally aspirated and the maximum fuel setting for engine operation when the supercharger is in operation respectively.

4. An apparatus according to claim 3 including resilient means in said pressure responsive means for biasing said worm wheel to said first position.

5. An apparatus according to claim 4 including a main housing in which are mounted said first and second members and said further member, and a body engageable within a recess in the housing, said body mounting said pressure responsive means.

6. An apparatus according to claim 5 in which said worm wheel is provided with an extension rod extending within a bore in said body, said body and worm wheel being shaped so that they can move in an axial direction relative to each other but are restrained against relative angular movement whereby angular adjustment of the body will effect angular adjustment of said worm wheel.

7. An apparatus according to claim 6 in which said first position of the worm wheel is determined by the abutment of the worm wheel with the body under the action of said resilient means.

8. An apparatus according to claim 7 including a plug member slidable within said body and forming part of said pressure responsive means, means connecting said plug member and said extension rod and means for limiting the movement of said worm wheel from said first to said second positions.

9. An apparatus according to claim 8 in which the means, connecting the extension rod and plug member comprises an adjustable screw thread connection, the means for limiting movement comprising a flange formed on said plug member engageable with said body, the distance moved by said worm wheel as it moves between said first and second positions being determined by the extent of engagement of said plug member and said extension rod.

10. An apparatus according to claim 9 in which said resilient means comprises a coiled compression spring acting intermediate said plug member and a step defined in the bore in the body.

11. An apparatus according to claim 10 including a diaphragm located within a housing secured to said body, said diaphragm engaging said plug member and an inlet in said housing whereby one side of the diaphragm can in use, be subjected to the pressure of air delivered by the supercharger, said diaphragm when subjected to said pressure imposing a force on said plug member acting in opposition to the force exerted by said resilient means.

12. An apparatus according to claim 11 including means for retaining said body against angular movement and axial movement within said recess.

13. An apparatus according to claim 3 in which said one member is of annular form and is angularly and axially movable, said means coupled to said one member comprising a fluid pressure responsive piston, which controls the angular setting of said one member, said piston being movable from a first position in which an excess of fuel is supplied by the apparatus for starting purposes to a second position corresponding to normal operation of the engine.

14. An apparatus according to claim 13 including resilient means biasing said piston to said first position and manually operable means for retaining said piston in said second position, said manually operable means being movable to allow the piston to move to said first position when an excess of fuel is required to be supplied by the apparatus.

15. An apparatus according to claim 14 including an inlet to the cylinder containing said piston, said inlet being connected to the outlet of said pump means, and a valve for controlling flow through said inlet, said valve including a valve which can co-operate with a seating.

16. An apparatus according to claim 15 in which said valve member is held in the seating by an abutment carried by the piston when the piston is in said first position, said valve member being subjected to said fluid pressure and thereby imparting to the piston a force acting to move the piston against the action of the resilient means.

17. An apparatus according to claim 16 in which said valve member is lightly biased away from said seating, whereby said piston can move quickly to said first position, the fluid displaced by said piston passing through said inlet.

18. An apparatus according to claim 17 including a leakage path controlled by said piston and which is opened by the piston as the latter moves towards said first position, said leakage path venting the space between the piston and the valve.

19. An apparatus according to claim 15 in which said valve mem-ber is urged into contact with the seating by further resilient means interposed between the valve member and the piston.