From for instance US A-4 512 307, GB A-2 045 349 and US A 4 449 500 are already known methods and regulation de- vices enabling regulation of the maximum supplyable fuel amount in dependence on a control pressure from the intake pressure of the engine. The suggestions disclosed in these pat- ent publications mean that the maximum fuel amount, the full load amount, can be adapted to the present charge pressure of a supercharged diesel engine. Thereby one can get an adequate adaptation of the fuel amount throughout the entire rotation speed range. If supercharging not takes place in the entire rota- tion speed range, something that for instance is the case with turbo-charged diesel engines, the maximum fuel amount, the full load amount, can be of a relatively low initial value when super- charging does not take place but by means of the adjusting de- vice can be achieved that at increasing supercharging resulting in increasing control pressure from the intake system of the en- gine the maximum fuel amount also is increased.

A disadvantage with the known embodiments according to these patent publications is however that they are relatively compli-

cated. More specifically, the degree of complexity is such that these regulation devices will have to be finished in intended condition already at the production. For instance the regulation devices according to US 4 449 500 and US 4 512 307 are based on regulation slides, which at axial motion influence pivoted lever tools, which in turn influence the adjustment members, de- signed as arms, for full load amount in the injection pumps. Ex- pressed in other words, these regulation devices require con- structive adaptations of the injection pump already in the con- struction stage. The same holds for the regulation device ac- cording to GB 2 045 349, where the function more specifically is such that the regulation slide at increasing fuel full load amount moves outwards from the pump housing while a knee lever tool allows increasing full load amount until finally a regulation rod for full load amount comes into abutment against a stopping member, placed in an opening in the pump housing, which con- sequently defines maximum full load amount.

It is desirable to be able to convert a non supercharged diesel engine to a supercharged design. The known regulation devices according to above discussed patent publications are not practi- cally usable here, since they in reality would require that com- pletely new injection pumps were applied to the engines referred to.

A further advantageous possibility would consist of being able to, as well initially in factory as later after selling a certain diesel engine together with injection pump, freely choose to what ex- tent supercharging is desired or not, and in connection with that easily be able to adapt a certain basic design of the injection pump to presence or absence of supercharging according to de- sire.

The object of the present invention is to provide conditions to with constructively simple means implement a method and a regulation device for an injection pump for a diesel engine

where supercharging is to be choosable without therefore the in- jection pump having to be specially manufactured for this pur- pose.

A further object with the invention is to propose a method, by means of which an injection pump for a diesel engine shall be able to be given regulatability with respect to maximum supply- able fuel amount in dependence on a control pressure from the intake system of the engine with constructively very simple mesures.

The object according to the invention is achieved by that the methods according to the invention and the accompanying regulation device are assigned the characteristics apparent from the characterising parts of following patent claims 1-2 and 4.

The defined characteristics of the object of the invention allow a certain basic type of injection pump, which initial not neces- sarily needs to be intended to master supercharging conditions, to easily be given such ability by applying, in an opening in a housing of the injection pump, the displaceable regulation bar of the adjusting device according to the invention so that it can in- fluence the adjustment member for full load amount in the injec- tion pump. In this opening normally in cases when supercharg- ing not is desired a regulation member is received, which in practice normally has the character of an adjusting screw, which is fixed in a determined position meaning limitation of the maxi- mum fuel full load amount to an initial value. This initial value is normally adjusted in a factory or by experts in a workshop so that not unwanted discharge of exhaust gas and soot particles arise. When however, the injection pump referred to shall be equipped for supercharging, the displaceable regulation bar of the adjusting device according to the invention takes over the function from this regulation member/adjusting screw so that a, during function changing, regulation of the maximum supplyable fuel amount is achieved in the dependence on the control pres-

sure derived from the intake pressure of the engine, the control pressure consequently depending on the utilised supercharging. By, for application of the adjusting device according to the in- vention, using the already by means of said opening obtained mounting possibility in practice no interference in the injection pump are required other than removing the existing regulation member/adjusting screw. As already implied, the present inven- tion is with advantage used for afterwards application of super- charging on existing engines/injection pumps but the invention just as suitable for the factory situation in that one and the same injection pump according to desire can be chosen for an engine installation without supercharging by in the said opening in the pump housing applying the regulation member/adjusting screw or for a design with supercharging, when instead the adjusting device according to the invention is applied at the pump housing so that its displaceable regulation bar extends into the pump housing through the opening.

By in accordance with the invention being able to regulate the maximum injection amount of fuel which in the injection pump can inject into the combustion chamber of the engine at every moment in dependence on the current charged pressure an ad- aptation, as well at the maximum charging of air achieved by the supercharger, as in lower rotation speed ranges, is obtained of the amount of fuel so that the relation air/fuel in the combustion chamber can be contained within the scope valid for a correct combustion of the fuel, and so that a smokeless combustion can occur.

The invention will now described in the form of a non-limiting embodiment, illustrated on the sole drawing showing a sectional view through an adjusting device according to the invention with co-operating parts in the injection system.

An injection pump for a diesel engine is in the figure illustrated by a pump housing 1, and a number of parts arranged in the

pump housing and parts extending out through the pump hous- ing 1 for co-operation with the parts inside the pump housing.

There is a throttle arm 2, which outside the pump housing via suitable control is connected to a throttle pedal in a vehicle. The throttle arm 2 is via a regulation spring 3 connected to a tension arm 4 and a starting arm 5 which influenced by a regulator 6 counteracts the rotation of the tension arm 4 around a joint 7.

Connected to the tension arm 4 is further a regulation arm 8 in- fluencing a regulation slide 9 which in turn influences a control channel 10 which supplies the fuel to the injection nozzles (not shown). By displacement of the regulation slide 9 along the control channel 10 a regulation of the amount of fuel supplied through the control channel can be achieved, in that the side channel 10a on the control channel more or less is closed by the regulation slide 9. To regulate the maximum amount of fuel that the injection pump can deliver there is provided an adjustment member 11, here in the form of an arm, for full load amount.

This adjustment arm 11 is hinged at a joint 12, and also that in- fluences the regulation arm 8 and can thereby displace the regu- lation slide 9 somewhat. At a displacement to the right in the figure of the regulation slide 9 by means of the adjustment arm 11 for full load, an increase of the maximum amount of fuel that can be supplied to the combustion chamber is achieved. This maximum full load amount is however, at the type of injection pump here referred to, normally limited of an adjusting screw, which is fixed, to not allow the maximum fuel amount to be in- creased when an increase of the fuel amount leads to an in- crease of the discharge of soot particles. A displacement of the regulation slide by means of the adjusting screw leads not only to an increased fuel amount at full load, but also gets this effect throughout the entire rotation speed register for the engine, with increasing soot discharge as a result. The adjustment arm 11 is also loaded from the tension arm 4 by a spring 11 a loading the adjustment arm 11 against the said adjusting screw. The herein- before described parts of an injection pump are parts which

conventionally exist in the injection pumps, to which the inven- tion is intended to be applied.

According to the invention, instead of the above mentioned ad- justing screw, an adjusting device 13 having the character of additional equipment and having the same function as an ad- justing screw is provided, but being able of adapting the adjust- ment for full load amount in relation to the supercharging pro- duced by the supercharger, and thereby the fuel amount can be adapted to the amount of air supplied to the engine.

The adjusting device 13 comprises a housing 14, with a sleeve part 15 which is screwable into the pump housing 1 instead of the previously discussed adjusting screw. The sleeve part 15 in its maximum screwed in position has a length such that the end of the sleeve part abuts against the adjustment arm 11 for full load amount inside the injection pump and determines the basic position for the adjustment arm 11 and with that also the regula- tion slide 9. The sleeve part 15 surrounds a regulation bar 16 which is somewhat axially displaceable inside the sleeve part, so that the regulation bar in one of its end positions is drawn in inside the end of the sleeve part 15 or at maximum is aligned with this end. From this one end position, the regulation bar 16 can be displaced axially so that it extends out over the end on the sleeve part 15, and can influence the adjustment arm 11, so that it in its upper part is displaced to the left as viewed in the figure. The housing 14 of the adjusting device 13 houses also a chamber 17, in which there is a diaphragm 18 as well as a spring 19 with a spring cup 20.

The diaphragm/spring cup is provided to be able to press against the other end of the regulation bar 16, i. e. the end passing through the sleeve part 15 and extending into the cham- ber 17. The diaphragm/spring cup 18/20 is normally loaded by the spring 19 against the regulation bar 16, and it is normally (in the initial position) provided situated aligned with the end of the

sleeve part 15, against which the adjustment arm 11 is loaded by the spring 11 a. The force in the spring 19 is however adapted so that with normal pressure in the chamber 17, the spring 19 is not capable by means of the spring cup 20 of pressing out the regulation bar 16 past the end of the sleeve part 15, due to the counter force from the adjustment arm 11 and the spring 11a.

To the chamber 17 there is further a connection 21, for connec- tion of a control pressure from the intake system of the engine. Through this connection 21 can consequently the pressure in the intake system of the engine be supplied, the pressure being dependent on the supercharging of the engine. When the control pressure, which is supplied in such manner via the connection 21, is supplied into the chamber 17 and acts on the diaphragm 18, the pressure inside the chamber 17 together with the force from the spring 19 will overcome the counter force from the ad- justment arm 11 and the spring 11a and displace the spring cup 20 to the left in the figure, to the position drawn in the figure.

Then the diaphragm/spring cup 18/20 will press the regulation bar 16 to the left, and it then influences in turn the adjustment arm 11 which is rotated in counter clock-wise around the joint 12. Then also the regulation arm 8 is rotated in counter clock- wise, which leads to a displacement of the regulation slide 9 to the right, so that the side channel 10a of the control channel completely is shut, and that all fuel flow through the control channel, and further to the engine, which with that gets an in- creased fuel amount compared to when normally the side chan- nel 10a is at least partly open, and a part of the fuel amount can flow out through it.

When later the pressure in the chamber again drops below the level when the spring force from the spring 11a overcomes the total force on the diaphragm 18 and the spring 19, the regulation bar 16 will be displaced to the right in the figure, and be drawn into the sleeve part 15. Then the adjustment arm 11 thanks to the influence from the regulation spring 3 and the spring 11a

can be rotated in clock-wise direction until the adjustment arm hits the end of the sleeve part 15. In connection with that also the regulation arm 8 is rotated clock-wise, and then displaces the regulation slide 9 to the left in the figure, at which the side channel 10a opens, and the fuel amount supplied through the control channel decreases.

With the method and the regulation device consequently a pos- sibility to, in dependence on the charge pressure of the engine, change the maximum fuel supply amount is achieved, and in that manner a possibility to fully use the resources of the engine is obtained without this necessarily leading to an unwanted dis- charge of soot particles due to too large fuel amount in relation to the amount of air. At the transition from a less loaded condi- tion to full load condition, in addition a gradual increase of the turbo-charge occurs, and then there is a slight delay before the increase of the fuel amount caused by the displacement of the regulation slide has effect. All of this is achieved without con- structive modifications by simply putting the adjusting device according to the invention in the opening for the adjusting screw instead of the existing adjusting screw.

The adjusting device according the invention could be adapted to different engine sizes and types by suitable choice of dimen- sions, well judged spring forces and area of the diaphragm, without needing to interfere with the basic adjustments of the injection pump.

The method and the regulation device according to the invention can be used as well on new engine constructions as for after- wards mounting on existing diesel engines, especially in con- nection with converting of these to a supercharged design. It is pointed out that the initial value (minimum value) for the full load amount can be determined either by the regulation bar 16 in its withdrawn end position or by the sleeve part 15.