US2236553A - Fuel injection apparatus for internal combustion engines - Google Patents

Description

April 1, 1941. w. VOI.T Ema.

FUEL INJECTIOK APPARATUS FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet '1 Filed Dec. 16, 1936 W. VOIT EI'AL April 1, 1941 FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Dec. 16, 1936 2 Sheets-Sheet 2 tinder the influence of a spring Patented Apr. 1, 1941 FUEL INJECTION APPARATUS FOR IN TERNAL COMBUSTION ENGINES Willy Voit, .Stuttgart-Bad Cannstatt, and Johannes Weber, Stuttgart -Feuerbach, Germany, assignors to Robert Bosch Gesellschaft mit beschriinkter Haftung, Stuttgart, Germany Application December 16, 1936, Serial No. 116,226 In Germany December 23, 19.35

9 Claims.

This invention relates to fuel injection apparatus for internal combustion engines, comprising a fuel injection pump, control means in said and the other with the induction pipe of the engine. The two chambers are separated from one another by a movable governor member, e. g. 9; piston or a membrane, and said member is means which tends to move said member in the direction ofincreasing fuel delivery wherea the negative pressure or vacuum in the inducton pipe causes the member to move, in opp sition to said pump for adjusting the fuel delivery of the pump, I

spring means, in the direction of'decreasing fuel delivery.

" When employing this kind, the different loads on the engine are adjusted for by a movable throttle which is arranged in the induction pipe of the engine.

By closingorpartially closing the, throttle, the

airflow in the pipe can. be restricted so that the vacuum in the governor chamber connected therewith increases. With the increase of this vacuum the movable governor member is moved in such a way as to decrease the fuel delivery. In this case the movement of the governor member takes place in opposition to the spring means. By fully opening the throttle the vacuum will decrease and adjust the control means so that the injection pump delivers large amounts of fuel and the engine runs with full power.

J With the throttle in its open or full power 3 position; many different engine speeds occur, especially in vehicle engines, and it depends on fuel injection apparatus of the maximum engine speed has'been' exceeded.

This type of governor can also be used for ad justing the fuel supply at loads less than full engine load byclosing the throttle sufficiently to decrease the supply of fuel accordingly.

In internal combustion engines in which full load'occurs over a great range of speeds, as principally in vehicle engines, it is important to take steps to enable the greatest possible torque to be obtained from the engine at any speed. A very important preliminary'condition for this is that, at each speed, the maximum amount of fuel which the engine can burn'without producing smoke, should be supplied to it. This amount varies with the speed in most types of engines. It may increase as the speed increases, in some cases however it remains the same over the whole range of speeds but usually the amount of fuel for running under 'full load that can be burnt withoutsmoke will decrease as the speed rises.

. For any engine the maximum amount of fuel that can be consumed without smoke when running under full load can be experimentally determinedfor each speed. If the ascertained values are inserted in a system of co-ordinates, a curve is obtained, which may be termed the consumption curve. According to whether this curve rises, remains the -same, or falls, as

the engine load whether the engine speed is high or low. A high load reduces and conversely a small load increases the engine speed.

It is well known to those skilled in the art theta pneumatic governor of the type described Y can be used to avoid an undesired increase of the engine speed beyond an admissible maximum. When the engine has exceeded the maximum speed at which it gives its full output, the vacuum in the governor chamber connected with the induction pipe will increase to such,a degree that it displaces the movable governor member, against the opposing spring means, and with it the control means, into its no delivery position, thus fully cutting off the fuel delivery to the engine. With the throttle in its fully open position, the fuel supply can be cut off only when the speed increases, the engine can be spoken of as having a .rising, uniform or falling consumption curve.

The course of the. consumption curve of an engine depends on various circumstances. The falling consumption curve will be frequently met with,.more especially in the case of engines hav ing a high maximum speed, because the air .charge in the engine cylinders decreases considerably for known reasons in the higher speed range, so that the maximum amount of fuel which can be consumed without producing smoke also correspondingly decreases.

In injection internal combustion engines, the

injection pump measures the amount offuel.

Every injection pump has a definite delivery amount curve which is produced on a definite, unvarying adjustment of the delivery amount adjusting member depending on the different speeds. Pumps having inlets controlled by sliding valves have for example a delivery curve that rises withthe speed; Other pumps, for instance those having the usual suction valve, have a delivery-curve which remains fairly uniform over the range of speeds that occur.

If now it is desired to introduce the maximum amount of fuel consumable without smoke into an injection engine in the whole speed range, in order to enable the highest possible torque to be obtained from the engine at all speeds, attention must be given primarily to making the delivery curve of the injection pump apparatus assimilate or conform as far as possible to the course of the consumption curve of the engine. The best conditions result, of course, when the two curves coincide.

This invention provides a new way in which in a simple manner, in spite of the comparatively great pressure or high pretension and small stiffness of the return spring necessary for cutting off of the fuel supply when maximum speed is exceeded in injection apparatus having pneumatic governing, the amount of fuel delivered to the engine can be regulated in such a way that the delivery curve of the injection apparatus can be adapted or coordinated to the consumption curve of engines having a strongly falling consumption curve so that at each speed at full load the engine operates with maximum power and with smokeless combustion.

According to the present invention, in a fuel injection apparatus for internal combustion engines comprising an injection pump having a full loaddelivery curve which rises relatively to the consumption curve of the engine as the speed increases, and a pneumatic governor which controls the fuel amount delivered by the injection pump to the nozzles and adjusts the delivery amount controlling member of the injection pump in dependence on a return force and on a pneumatic drop in pressure acting in opposition to said return force, which drop in pressure varies with the engine speed as well as with the position of a voluntarily operable throttle, a novel return force is provided wh eby under full load conditions, that is to say, i' a range between full load at low speed and full load at maximum speed, the effective resultant value of the said return force is such that the difference in depression occurring within this full load range due to differences in speed of the engine can cause by a corresponding displacement of the control member, an assimilation of the fuel delivery curve of the pump to that consumption curve of the engine which gives smokeless combustion at each speed at full load to enable the engine to operate at maximum efiiciency, said return force also coacting, however, with the pposing depression or increase, to regulate the fuel amounts when maximum speed is exceeded and at all speeds less than maximum under partial load.

The return force acting on the governor meniber of the pneumatic governor comprises a 2- stage spring means, one stage of which has a high pretension corresponding to the vacuum existing at maximum speed in the governor chamber but of such weakness that it is overcome by a further increase of vacuum when the maximum speed is exceeded, the other stage of said spring means having a low pretension, if any, corresponding to the slight vacuum existing below maximum speed with wide open throttle, but of such a strength that below maximum speed and with wide open throttle it adjusts the control means to the slight vacuum and small variations of vacuum in the induction pipe of the engine so that the control means causes the pump to deliver the maximumquantity of fuel which can be burned smokelessly.

Various examples of construction of the invention are shown in the accompanying drawings in which: V

Figure 1 shows, partly in longitudinal section a fuel injection pump provided with a vacuum or pneumatic governor embodying this invention. Figure 2 is a diagram of the curve of the spring forces of the injection pump governor.

Figure 3 is a diagram of the delivery curve 01 the pump and the consumption curve of the engine.

Figures 4, 7, 10 and 13 are enlarged sections of different examples of construction of spring stops for the delivery amount adjusting member of the pump, while the curves of the spring forces and the maximum delivery amount of the pump appertaining to each example are indicated in the diagrams (Figs. 5, 6, 8, 9, 11, 12, 14, 15) adjoining said figures.

- l indicates the injection pump, the cam-shaft 2 of which drives the pistons 3 of several separate pumps. On this injection pump a pneumatic governor 4 is built, in which a diaphragm 5 moves a toothed controlling rod 8 of the injectionpump. By the movement of the controlling rod all the pump pistons are uniformly angularly turned or r0tated,'whereby an oblique helix controlling edge arranged on the end of each piston is adjusted in relation to a return flow opening, so that a variable amount of the fuel forced by the pistons can flow back. An externally closed governor chamber 1 of the pneumatic governor 4 is connected by a pipe 9 to the induction pipe 8 of the engine, the other governor chamber ll being open to the atmosphere. A throttle member ID is rotatably mounted in the induction pipe 8 of the engine and by closing or partially closing the throttle ID, a vacuum is producedin the chamber 1. The vacuum will displace the diaphragm 5 and this in turn displaces the control rod 6 in the direction which decreases the amount of fuel injected. The opposite movement of the control rod 6 takes place when the vacuum in the chamber I decreases, e. g. by adjusting the throttle into the open position as seen in Fig. 1. With the throttle in its open position, a smaller vacuum arises than when it is in its closed or partially closed position. The. opening and closing movement of the throttle and the speed of the engine are made use of to adjust both large or small injection amounts at full or part engine loads. The throttle in the present case is used primarily to control the vacuum in the governor chamber and for this reason it is only necessary to partially close the throttle to obtain sufllcient vacuum to adjust the fuel delivery for part load and idling speeds. Within the chamber '1, there is arranged a spring I! which presses the diaphragm 5 and the control rod 6 towards the left hand side in Fig. 1. The force of the return spring l2 tends to adjust the diaphragm and the controlling rod in the direction which increases the amount of fuel injected.

An injection pump of the type shown has per se a rising delivery curve according to the line A and the curve of the maximum fuel amount consumable by the engine, without producing smoke, may have a course indicated by the broken line C in Fig. 3. In order to assimilate the delivery curve of the injection pump fitted with a pneumatic governor to this consumption curve, which falls as the speed increases, an opposing spring I3 is so arranged on the left hand end of the pump casing I as shown in Fig. 1, that it bears with one of its ends against an adjustable bottom or stop member I in a sleeve I4, while the other end of the spring I3 bears on a movable stop IG for the left end of the controlling rod 6. The springs I2 and I3 prevent the pump from delivering amounts of fuel over and above those shown by curve C, provided the throttle is fully open.

When the engine is not running there is no vacuum either in the induction pipe 8 or in the governor chalinber I. The springs I2 and I3 are now the only forces which have influence on the control rod "'8 and keep it in a certain position of equilibrium.

When the engine is in operation, a vacuum will arise in both the induction pipe 8 and the chamber I, which vacuum will have the tendency to draw the diaphragm 5 towards the right for decreasing the fuel delivery amount, which movement is opposed by the resultant force of the springs.

The left end of the controlling rod stands, when the engine is stopped or not running, in the position Ia, as in this case no drop in pressure acts on the diaphragm, so that the pressure of the return spring I2 and that of the opposing spring I3 are equal. If now the engine is running under full load (i. e. the throttle valve fully open) at a slow speed, for example when the car is traveling uphill, the left end of the controlling rod is in the position denoted by I.

At a high full load speed the current in the air induction pipe is stronger, so that the vacuum in the governor chamber increases somewhat and pulls the diaphragm more to the right, until the left end of the controlling rod in the region of maximum speed reaches the position II. In this position of the governor parts the force exerted by the opposing spring I3 on the controlling rod has been expended, and upon a further increase in speed and in vacuum, the control rod is moved further to the right so that the left end of the controlling rod comes out of the range of action of the opposing spring. In position III of the end of the controlling rod, only the amount of fuel necessary to maintaining idle running is still delivered. The controlling rod moves into this position III when the throttle valve is fully open when maximum speed is exceeded. With the throttle valve partially closed (idle running adjustment), the vacuum then existing in the induction pipe 8 and in the governor chamber 1 is also able to pull the controlling rod into position III. The stop position of the controlling rod is indicated at IV.

The spring I2 has the characteristic indicated by I2 in Fig. 2, a diagram in which the ordinates show the force exerted by the springs and the abscissas the stroke of the movable end of each of the springs. The positions of the left end of the controlling'rod in Fig. 1 correspond to the spring path IaIV in Fig, 2. The spring I3 has the characteristic indicated by numeral I3 in Fig. 2 and shown by a dotted line below the axis of abscissas to illustrate that spring I3 works in the opposite direction to spring I2. In position Ia both springs have the same tension in opposite directions and are in equilibrium. From Ia to II the tension of spring I3 decreases until at II the spring I3 has fully expanded. Between Ia and II the springs l2 and I3 work together like a spring with the resultant characteristic X in Fig. 2 and as if such a resultant spring were opposed I to the vacuum in the chamber 1.

chamber 1 increases with increasing engine speed because with increase in speed the velocity of the air-flow also increases. With the throttle in its open position the vacuum in the pipe 9 leading into the induction pipe and in the chamber I is relatively small as long as the engine is running at slow speed under full engine load because the velocity of the air-flow in the induction pipe is also small. The vacuum increases with increasing engine speed and becomes at the maximum speed so great that it overcomes the relatively high pretension of spring I2.

Fig. 1 shows the control rod 6 with its left end in the position I, but it will stand in the position Ia when the engine is stationary and the pressure is the same on both sides of the diaphragm 5. From the Ia position in which equilibrium exists between the springs I2 and I 3, the control rod moves towards the right as soon as the vacuum in chamber 1 overcomes the resultant spring force X. In order to achieve this a small vacuum will be sufiicient as the strength of X near Ia in Fig. 2 is small. In fact, even the small vacuum will suifice which occurs in chamber 1 when, with the throttle in the open position and with high engine load (e. g. driving uphill) the engine speed has very much decreased, for instance down to the lowest speed at which the engine is still able to operate under full load. In the following, this lowest speed will be referred to as lowest full load speed. The position of the control rod 6 corresponding to the lowest full speed is that indicated by I in Fig. 1. Now, if with decreasing torque the engine speed and the vacuum increaseswhile the throttle remains in its open position-the increasing vacuum will further shift the control rod Ii towards the right against the resistance of the spring the strength of which increases corresponding to the rising course of X. Between I and II in Figs. 1 and 2 the shifting movement of the control rod 6 will terminate in those positions in which the vacuum and the strength of the resultant X are in equilibrium. The springs l2 and I3 are so dimensioned and the resultant X so chosen that with increasing speed-the throttle, be it remembered, always being open-the left hand end of the control rod 6 has reached the position II at the maximum en-.

gine speed. That is the highest possible engine speed which is admissible for the engine under full load. In this position II the spring I3 has fully expanded and the stop I6 touches only lightly the left hand end of the control rod 6. If because of further decreasing engine torque (for instance when driving downhill) the engine speed exceeds the maximum speed, the vacuum would further increase; but as the expanded spring [3 no longer operates at the right hand side of II-in which position only spring I2 Works-at II another range of governing will begin. Here, only the spring I2 will resist the increasing vacuum. As according to Fig. 2 the stiffness of the spring I2 is very small, only a small increase of vacuum, corresponding to a small increase of speed over maximum speed, is necessary to shift the control rod 6 towards IV and so fully cut-of the fuel delivery at a speed which is not very much higher than maximum speed. Thus by exceeding the maximum speed only slightly the fuel delivery is fully cut-off, while below maximum speed the stiffer characteristic X will cause an even alteration in the amount of fuel delivered in dependence on variations of engine speed as Fig. 3 is intended to show.

It will be seen from this diagram that the coaction of the spring I2 and I3 only takes place between stop position (Ia) and the maximum speed at full load position (II). When the speed exceeds the predetermined maximum speed at full load the final regulation or cutting off of the fuel supply starts, and the return spring I2 is increasingly compressed by the increasing vacuum until the idling amount adjustment (III) and finally the stop position (IV) of the controlling rod is reached.

In Fig. 3 the maximum speed is indicated by m and the lowest full load speed by m. It has already been mentioned that between these two limits of speeds one stage X of the spring means comes into operation, i. e. the stage in which both springs I2 and I3 operate, while above 11.2 in the other stage only spring I2 is opposed by the vacuum.

According to the present invention the strength of the resultant spring means X is such that the delivery curve A of the pump is assimilated as d which is practically the same as that of the commonly known maximum speed regulator cuttingoff fuel supply at maximum speed.

It will be seen, therefore, that according to this invention, the control of the fuel amount takes place in the full load speed range by the coaction of the forces in a different way than if only the fall in pressure and the main return spring I2 were operative.

Fig. 4 relates to another embodiment of the invention. If differs from Fig. l by the fact, that the stop I6 has a prolongation I! which extends through the bottom of the sleeve Ma and can at will be drawn manually further to the left, beyond the position Ia in which it would stand when the engine is not running, into a position ID in which the stop I6 bears on the bottom of the sleeve. When the engine is out of operation and the stop I6 has been drawn manually to the left, the control rod will follow the stop under the pressure of spring I2 until the end of the control rod 6 has reached the ID position. In this condition, the injection pump is so adjusted that the pump delivers an excess amount of fuel which in many cases is desirable for starting the engine.

During the excess fuel adjustment period the left, excess fuel amounts can be adjusted which according to the left hand part of curve C between 11.. and m in Fig. 6 are shown to be larger than the full load delivery amounts between m and n2, adjusted by the springs I2, I3 after the stop has been released so that the springs can cperate in the manner described in Fig. 1.

In Figure 5, as in Figure 2, the strength of the springs I2 and I3 are plotted as ordinates over the length of spring travel, the positions of the left hand end of the control rod in Fig. 4 corresponding to the spring travel 11) to IV of Fig. 5. The combined action of the springs I2 and I3 is shown by the line X (Fig. 5) disposed between the position 111 and the maximum speed position m Fig. 6). The left hand end of the control rod moves in this speed range from the position Ia to the position II (Fig. 5).

If prior to starting the engine, the driver manually displaces the excess fuel stop IE to the left,-

then the tension of the spring I3 is overcome by him in the position Ia of the control rod so that spring I3 no longer acts in opposition to the spring I2, which latter spring is then free to expand so that the control rod moves until its left hand end comes into position Ib in which this control rod, when the engine throttle is wide open and the engine is revolving at low speed sets the pump to give an increased quantity of fuel, which is often desirable at starting of the engine. This condition is shown in Fig. 6 in which the quantity of fuel injected per stroke is plotted against revolutions per minute.

Should the excess fuel device he pulled back, the fuel delivery curve would rise throughout the range, above the curve A and parallel thereto but as the governor comes into operation at or about the point 121 this curve will take the form shown at C-where only the first part of the curve lies above the curve A but the latter part of the curve falls below it.

Further according to this invention, the strength of the opposing spring can be adjusted. An example of such an arrangement is shown in Fig. '7. One end of the opposing spring I3 bears on the adjustable bottom or stop I5 of the sleeve Ma, and the other end bears on the movable con-. trolling rod stop I6. At a low full load speed (position It.) the stop I6 impinges on the bottom I5 of the sleeve Ida, while the spring I3 is compressed. As the stop I6 impinges on the bottom I5 before the left end of the controlling rod has reached a position Id equivalent to the position Ia, of the above examples, in which it would stand on nonrunning of the engine, if the stop was not present, a condition of equilibrium of the springs I2 and I3 cannot occur as in the arrangements shown in Figs. 1 and 4. The adjust-able bottom is moved, furthermore, according to Fig. 7 beyond the non-running position Id (Ia as indicated in Figs. 1 to 4) somewhat further to the-right into osition Ic, so that the end of the controlling rod approaches still nearer the position 11 that corresponds to the maximum speed at full load. In this initial position the pressure of the return spring preponderates over the opposing spring in the region of low full load speeds (Fig. 8) so that thereby the controlling rod is pressed against the stop. With the throttle valve fully open and low full load speeds, no assimilatory action of the opposing spring takes place, because the controlling rod does not move, and the delivery amount of the pump increases as shown by the line A (Fig. 9). It is only when a higher full load speed is reached (as indicated at point no Fig. 9) that the drop in pressure can overcome the pressure of the return spring against the stop, and then the cpposing spring can act to cause assimilation by reducing the delivery amount of the pump. The resultant of the two spring forces increases owing to the increase in the drop in pneumatic pressure as shown in Fig. 8 only from a definite speed us which corresponds to the stop-position 10 of the left end or the controlling rod, until the maximum speei at full load n: is attained, when the cutting off of the fuel feed begins. The delivery amount of the pump, increasing at first with the curve A, is this assimilated to the consumption curve of the engine, as shown in Fig. 9, from the full load speed 12.: onward according to the curve C.

If now the bottom I5 of the sleeve I5 is moved to the left, the return spring can displace the left end of the controlling rod into the position Id against the opposing spring, while the return spring further expands. Accordingly at first, a.

123.1NTERNAL COMBUSTION ENGINES.

pended and cannot operate any longer.

somewhat larger injection amount is adjusted. As the speed increases, however, the vacuum can now put the diaphragm and controlling rod somewhat earlier into movement and pull them to the right, during which the opposing spring acts in an assimilatory manner. The opposing spring will now also be earlier expanded (IId), as its abutment (bottom l) has also been displaced. Its assimilatory action thus ceases even before the maximum speed at full load is reached. The curve C' will thus at first lie above the line A and parallel thereto, then fall, and finally again rise somewhat up to the full load maximum speed. The assimilation can thus be limited, according to the invention, to a portion of the full load speed region.

Figs. 3 and 6, previously discussed, are based on the fact that the engine would have a fuel consumption curve C, C' respectively with a. falling tendency for the whole full load speed range between 11.1 and 11.2. In Fig. 9, the consumption curve C" is that of a combustion engine which can combust without smoke increasing fuel amounts up to us, (this curve coincides from n. to 11 with the delivery curve A of the pump), but from m to n: the consumption curve C" falls. In this case, an alteration of the fuel delivery of the injection pump below no is not necessary, but only above m. In order to obtain an alteration between nc and n: the bottom l5 of the sleeve Ila is to be adjusted as previously described so that the stop l6 does not permit movements of the control rod to the left beyond IO. The control rod 6 will then remain in this position as long as the speeds remain below us, the throttle being in the open position. Thus, below m the injection pump delivers according to its delivery characteristic A, while from m up to 122 the resultant strength X (see Fig. 8) of the springs I2, I 3 is in operation and from n: to m'the strength of spring I! alone.

In the case where the engine has a consumption characteristic shown by the dash and dotted line C' in Fig. 9 with deviations at nd and mm, with the same means as shown by Fig. 7, it will be possible to influence the injection pump according to curve C'. In order to achieve this result it is only necessary to slacken the bottom I!) of the sleeve Ha so far that the control rod 6 would be stopped at Id, while in the first-mentioned adjustment the lefthand movement of the control rod was limited at 10. In the same manner as during the previous adjustment Ic the injection pump delivered below us. according to its delivery curve A-because the control rod does not move below no with the open throttle-the small vacuum below nsin the open position of the throttle-will not move the control rod. Therefore, below 114 the injection pump will deliver with the control rod in position Id (which corresponds to a larger fuel delivery amount) according to a deliver curve the course of which is similar to the curv A but higher because the position Id of the control rod corresponds to a larger delivery amount than 10. Above na the vacuum increases and the resultant force X in Fig. 8 determines the delivery amounts. While with the stop in the Ic position the control rod will be adjusted by the resultant force X between m and m from In to II; the adjustment of the stop l6 into position Is will cause X to operate between Ia and IId when the speed increases from na to mm, a speed lower than m. From the said speed ndz onwards the spring 13 has fully :11:-

Search Room the spring l2 will still remain in operation. But the strength of spring I 2 at IIa (Fig. 8) is not much different from the strength at II and can, therefore, not be contracted by a vacuum which is not essentially smaller than that at m. For this reason, the control rod 6 keeps its position IId until the speed 12.: has been approximately reached. In position 11d of the control rod the pump will deliver according to a curve which is parallel to A (between nan and m) Above 112 the vacuum in the induction pipe will contract spring l2 and cut-off the fuel delivery in order to prevent the maximum speed 112 being exceeded.

Fig. 10 represents another example of construction, in which the left hand end of the stop I 6 is adjustable by a screw 18, but the bottom of sleeve Ma, which forms an abutment for one end of the spring 13, is immovable. While the screw I5 in Fig. 7 was the abutment for both the stop 16 and the spring I3 and so shifted when displaced the whole operating range of X in Fig. 8, in the present case only the left hand range of the operation of the control rod 6 is adjustable and the range which operates when the control rod 6 and the stop l6 are out of contact with one another cannot be altered. This will be seen from the following explanation.

By adjusting the screw I8 in such a manner that the right hand end of the stop l6 and the left hand end of the control rod 6 are in position I: (see Figs. 10 and 11), the resultant force X of the springs l2, l3 can only be operable between 11: and n: (Fig. 12). Below n: the injection pump will operate, without the position of the control rod 6 being altered, according to the curve C which has the same course as the delivery curve A of the pump. Above 11.: the pump will deliver fuel amounts according to the dotted line in Fig. 12 between m and m. If by a different adjustment of screw l8 the control rod is permitted to reach position Ie, the control rod can follow the stop I6 until at m (beyond 11:) a higher fuel delivery amount is obtained. From I: to I. a further decrease of X occurs as can be seen from the dotted part of the line X in Fig. 11. At the same time the fuel delivery amount increases between 12: and m as can be seen from curve C" in Fig. 12 which rises from m to m while below us the fuel delivery curve C" is parallel to the injection pump delivery curve A as the vacuum in the open position of the throttle at the low engine speeds below m cannot displace the control rod. According to this arrangement, it is possible to adapt the delivery curve of the pump to the consumption curve of the engine to the fullest possible extent.

Fig. 13 shows another embodiment of the invention and Figs. 14 and 15 are diagrams for illustrating the operation thereof. 1 is the governor chamber, which is formed by the governor casing 4a and the membrane 5. It is connected by the pipe 9 with the induction pipe of the engine. Within the casing there is arranged a spring II, which at one end rests upon the bottom of the casing la and at the other end presses a disc I! against astop ring 22 fixed to the cas ing. Stop ring 22 limits movement to the left of disc 19, movement thereof to the right being limited by stop 23. Under the pressure of the spring l2, the disc 19 forms a support for one end of a second spring 2| which at its other end bears on the diaphragm 5. In the position shown in the drawings, the spring I! cannot direct its whole pretension on the membrane, but only with the smaller tension of the spring H. The characteristics of the springs l2 and 2| can be seen from Fig. 14. As the pretension of spring 2| is very small compared with the pretension with which the spring I2 is pressed against the disc l9, the spring 2| alone will be contracted as long as small vacuums arise in chamber 1. In this case the parts 5, 2| and 6 will move without contracting the spring l2. During such movements of the control rod 6 under the small vacuum at open throttle below maximum speed 122, the delivery amounts of the pump-according to curve A in Fig. l5-will be reduced to amounts C in Fig. 15 which can be burned in the engine cylinders Without smoke.

The spring 2| has been dimensioned so that by the small vacuum at maximum speed 112 it will be contracted so far that the membrane 5 abuts against a tubular part 20 connected with the disc Ill. The membrane will abut against the tubular member at II in Figs. 13 and 14. When the vacuum further increases upon an increase of speed above maximum speed m, the membrane 5 will be drawn so much towards the right that now the pretension of spring I2 will be overcome, taking with it the control rod 6 and cutting-off the fuel delivery. From the foregoing it will be seen that, as in the previous examples, the example of construction according to Figs. 13, 14, 15 also has two stages of operation, one low vacuum stage in which a relatively stiff spring 2| of small pretension is opposed to the small vacuum occurring at open throttle below maximum speed and adjusts the fuel delivery of the pump in such a manner that the engine produces at each full load speed the maximum possible power without smoke, and another high vacuum stage in which a spring l2 of high pretension but of relatively weak chaacteristic (small alteration of strength in the large stroke between II to III) is operable to cut-off the fuel delivery above maximum speed.

We declare that what we claim is:

1. In an internal combustion engine of the injection type having an air intake manifold and a throttle valve therein, the combination comprising adjustable fuel injection means, a displaceable control member connected to said fuel injection means for controlling the quantity of fuel supplied to said engine, means housing said control member and defining with the two sides thereof two chambers, one on each side of said tions in the intake manifold will function to displace said control member by differential pressure acting thereon in opposition to said resilient force to adjust the fuel injection means, and resilient means operative only when said control member reaches a position for adjustment of fuel supply within the full load range of said engine and at speeds below maximum and then automatically Operating o p y a r istin force to said control member in opposition'to the force appliedbisaid first-mentioned force-applying means, the resultant force exerted on said control member by said opposed force-applying means being so weak that said control member is sensitive to and movable by the small pressure differences which occur in said chambers when the engine runs with wide open throttle under full load at speeds lower than maximum speed.

2. In an internal combustion engine of the liquid fuel injection type having an air intake pipe and a throttle valve therein manually operable at will, a fuel supply system and control means therefor adapted to control the speed of the engine, said fuel supply system and control means therefor comprising a fuel injection pump driven by said engine, a displaceable fuel quantity control member, means mounting said control member for movement in opposite directions, said control member being movable in one of said directions by difference in fluid pressures on its opposite faces, means exposing one face of said control member to atmosphere and its opposite face to the pressure in said intake pipe on the engine side of said throttle valve, means operated by said control member to reduce the fuel delivery of said pump in accordance with the displacement of said control member in said one direction, resilient means operable to apply a resisting force to said control member in opposition to the efiect of said difierential pressure, and auxiliary resilient means inoperative until said control member reaches a position for adjustment of the fuel delivery of said pump within the full load range of said engine at speeds below maximum and with wide open throttle and then automatically operating to apply a resisting force to yieldingly resist movement of said control member in the fuel-increasing direction, the resultant force exerted on said control member by the two resilient means being so weak that said control member is sensitive to and movable by the small fluid pressure differences to which said control member is subjected when the engine runs with wide open throttle under full load at speeds lower than maximum speed.

3. Apparatus as set out in claim 2 including means for adjusting the tension of said auxiliary resilient means.

4. In an internal combustion engine of the liquid fuel injection type having an air intake pipe and a throttle valve therein manually operable at will, a fuel supply system and control means therefor adapted to control the speed of the engine, said fuel supply system and control means therefor comprising a fuel injection pump driven by said engine, a displaceable control member, means mounting said control member for movement in opposite directions, said control member being movable in one of said directions by difference in fluid pressures on its opposite faces, means exposing one face of said control member to atmosphere and its opposite face to the pressure in said intake pipe on the engine side of said throttle valve, means operated by said control member to reduce the fuel delivery of said pump in accordance with the displacement of said control member in said one direction, resilient means operable to apply a resisting force to said control member in opposition to the eflfect of said differential pressure, and a resilient device located in the path of movement of said control member so as to engage said control member as it reaches a position for fuel delivery control for full load running of the engine at speeds below maximum and thereby to yieldingly resist movement of said control member in the fuelincreasing direction, the resultant force exerted on said control member by said resilient means and said resilient device being so weak that said control member is sensitive to and movable by the small f'luid pressure difl'erencestowhich said control member is subjected when the engine runs with wide open throttle under full load at speeds lower than maximum speed.

5. Apparatus as set out in claim 4 including manual means for temporarily rendering said resilient device inoperative during starting of the engine. l

6. Apparatus as set out in claim 4 including means for varying the end position of said resilient device in the direction of increasing the fuel amount.

7. A fuel supply system for internal combustion engines provided with an air intake pipe and a throttle valve therein, comprising a casing connected to said pipe at a point therein on the engine side of said throttle valve, a control member in said casing displaceable in opposite directions through a predetermined range of displacement and in one of said directions under the influence of reduced pressure, transmitted from said intake pipe to said casing, a fuel injection pump having a delivery curve which rises relative to the consumption curve of the engine as the speed increases, means connected to said control member and to said fuel pump operative to reduce the delivery of said pump in accordance with the extent of displacement of said control member in said one direction, resilient means operable to apply a resisting force to said control member in opposition to the effect of said reduced pressure, additional resilient means operable to apply a resisting force opposed to said first men tioned resilient means to said control member, said additional resilient means being ineflfective until said control member reaches a position of fuel delivery control for full load running of the engine at speeds below maximum and both resilient means cooperating to apply a resultant resisting force to said control member in opposition to the efiect of said reduced pressure which is weaker in the position of said control member for adjustment of the fuel delivery of said pump within the full load range of said engine at speeds below maximum and with wide open Cir throttle than at speeds higher than maximum,

the resultant force exerted on said control member by said resilient means being so weak that said control member is sensitive to and movable by the small fluid pressure diiferences to which said control member is subjected when the engine runs with Wide open throttle under full load at speeds lower than maximum speed.

8. A fuel supply system for internal combustion engines provided with an air intake pipe and a throttle valve therein, comprising a casing connected to said pipe at a point therein on the engine side of said throttle valve, a control member in said casing and displaceable in opposite directions through a predetermined range of displacement and in one of said directions under the influence of reduced pressure, transmitted from said intake pipe to said casing, a fuel injection pump having a delivery curve which rises relative to the consumption curve of the engine as the speed increases, means connected to said control member and to said fuel pump operative to reduce the delivery of Search Room said pump in accordance with the extent of displacement of said control member in said one direction, resilient means operable to apply a resisting force to said control member in opposition to the effect of said reduced pressure, said resilient means comprising a relatively weak spring and an opposing relatively strong spring, said Weak spring operating alone during a portion of the stroke of said control member and both springs cooperating to apply a resultant resisting force to said control member in opposition to the effect of said reduced pressure when the control member reaches a position for adjustment of fuel supply within the full load range of said engine at speeds below maximum, said resultant force being weaker than the force exerted by said weak spring alone and being so weak that said control member is sensitive to and movable by the small fluid pressure differences to which said control member is subjected when the engine runs with wide open throttle under full load at speeds lower than maximum speed.

9. A fuel supply system for internal combustion engines provided with an air intake pipe and a throttle valve therein, comprising a. casing connected to said pipe at a point therein on the engine side of said throttle valve, a control member in said casing and displaceable in opposite directions through a predetermined range of displacement and in one of said directions under the influence of reduced pressure, transmitted from said intake pipe to said casing, a fuel injection pump having a delivery curve which rises relative to the consumption curve of the engine as the speed increases, means connected to said control member and to said fuel pump operative to reduce the delivery of said pump in accordance with the extent of displacement of said control member in said one directionsa relatively strong spring of substantially no pretension and a pretensioned but relatively weak spring arranged in series to apply a reslsting force to said control member in opposition to the effect of said reduced pressure, and stop means between said springs to limit the exten sion of said weak spring and hold it under the desired pretension whereby essentially only the force exerted by said relatively strong spring is exerted on said control member when said control member reaches a position for adjustment of fuel supply within the full load range of said engine at speeds below maximum, the force exerted on said control member in opposition to the effect of said reduced pressure in the full load range of said engine being so weak that WILLY VOI'I. J OHANNES WEBER.

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