FR2463272A1 - FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

A. PUMP 1 WITH FUEL INJECTION FOR INTERNAL COMBUSTION ENGINES WITH AN ADJUSTING PISTON 3 CAUSING THE OFFSET OF THE INJECTION INSTANT, MOVABLE PISTON, IN ITS POSITIVE STROKE, BY PRESSURE, PROPORTIONAL TO THE ROTATION SPEED OF THE ENGINE , REIGNING IN ITS WORKING CHAMBER 4 AGAINST A RETURN FORCE REIGNING IN ITS RETURN RUNNING CHAMBER 12 AND WHICH IS MODIFIABLE ACCORDING TO THE CHARACTERISTICS OF THE MOTOR RUNNING. B. PUMP 1 CHARACTERIZED IN THAT, AS A RETURN FORCE, A PRESSURE LIQUID IS USED IN ADDITION TO A RETURN SPRING 5, THE PRESSURE OF WHICH IS MODIFIED ACCORDING TO THESE CHARACTERISTICS. C. THE INVENTION APPLIES IN PARTICULAR TO AUTOMOBILE ENGINES.

Description

The invention relates to a fuel injection pump

  burner for internal combustion engines with a control piston causing the injection timing to shift, piston

  displaceable, in its positive stroke, by a proportional pressure

  the speed of rotation of the motor in its working chamber, against a restoring force prevailing in its

  return race room, which can be modified into large outbuildings

  the characteristics of the engine running.

  In a known fuel injection pump of this type, the return force in position is exerted by a spring which is supported by an adjustable position counterweight.

  which can be positioned in dependence on characteristic quantities

  motor ticks. Since the variable pressure for the adjustment has to move a counter-support piston before an injection point adjustment has taken place by changing the

  force of spring, this system is struck by a delay inertia

considerably.

  From a regulatory point of view this is a

  multiplier commitment in which a magnitude of

  to know the pressure loading the counter-bearing, modifies

  the second control quantity, namely the return spring.

  The opposite influence of the control quantities makes it

  the mastery of individual quantities for different states with all the disadvantages that result for

  adaptation to the conditions required by the engine manufacturer.

  The subject of the invention is a pump for injecting

  characterized in that as a

  reliable, using a pressure fluid whose pressure is modifiable.

  This has the advantage that the intervention force

  Regulation is obtained by addition and, as a result,

  is easy to master and adapt. Thus, in dependence

  In the case of the engine's characteristic variables, in particular the temperature, but also the load or the load pressure or other quantities, the injection time can be moved in advance or late. Another advantage of the invention is that, for its realization, it suffices simply to mount some elementary building parts on a series-produced fuel injection pump. Depending on the needs, this insertion of elements can be constituted

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more or less important.

  The following description refers to several

  embodiments of the invention shown schematically in the accompanying drawings in which: - Figures 1, 2 and 3 show examples and a diagram for a delay setting in the case of bass

rotational speeds of the engine.

  FIGS. 4, 5, 6, 7 are representations

  analogous for the advance setting of the injection point.

  In the cam mechanism of a fuel injection pump 1 is moved, via a pin 2, an adjusting piston 3 for adjusting the start time of injection. The adjusting piston 3 can be displaced, by a pressure medium in a working chamber 4, against the action of a return spring 5, such that

  so that, insofar as the piston is moved in direction

  spring, the injection moment is advanced relative to the top dead center of the engine piston. The arrow indicates "more" setting in advance, and direction "minus"

the late setting.

  A displacement pump 6 draws fuel from a tank 7 and transports it into a suction chamber 8 of the injection pump 1, from which,

  in a manner not shown, the particular injection pump

  is fueled, which is connected to the

  work 4 by means of a drilling 9 provided in

  the adjusting piston 3. This piercing 9 has a point of

  10. Through a pressure control valve 11, the delivery pressure of the fuel pump 6, and thus the pressure in the pressure chamber 8, is controlled in dependence on the rotational speed of the engine. , this pressure increasing proportionally to the increasing speed of rotation of the motor. This pressure, which depends on the speed of rotation, also reigns in the working chamber 4, such that during an increasing speed, and consequently increasing pressure, the adjusting piston of the

  injection point is moved in the direction of advance ("plus").

  FIG. 2 is a diagram showing on the ordinate the stroke of the adjusting piston in

  function of the number of revolutions n of the motor represented on the abscissa.

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  Line I is the characteristic curve of point adjustment

  injection, for which the race and consequently the displacement

  cement advance increasing linearly with the number of revolutions.

  For many engines, it is desirable and even necessary, for starting and especially to obtain a rapid acceleration, to set the injection start time with cold engine, or under certain operating conditions, on "delay", at least until a certain number of turns is reached,

  as represented by the dashed curve II in the diagram.

  According to the invention, the intervention in the adjustment of the injection moment is carried out by modifying the fuel pressure in the return chamber for the return spring 5. This chamber 12 comprises a link 13 towards the chamber 8, this junction presenting a

choke point 14.

  In the first exemplary embodiment shown in FIG. 1, this constriction, as a bore 14, is provided in the wall of the injection adjusting piston 3, which, during its displacement stroke, after having traveled a determined course, separates the piercing 14 of the junction 13, and thus separates the return chamber in position 12 of the suction chamber 8. In the position shown, which however corresponds to a low speed of rotation of the engine, the adjusting piston of injection 3 is moved to the right by the pressure developed in the return chamber in position 12,

  that is, in the "delay" direction of the injection point.

  This is made possible by the fact that, in an evaluation

  cuation 15 of the return chamber 12, is disposed a pressure control valve 16 thermostatically actuated. As long as this valve is closed, the pressure prevailing in the suction chamber 8 and in the working chamber is established in the return chamber 12, so that the injection adjusting piston 3 is moved towards the right by the force of the spring 5 (in the injection delay position). The thermostat 17 of the pressure control valve 16 may be heated, either by an electrical resistance or directly by the cooling water of the engine to allow passage

  around the valve plug 18.

  Depending on the degree of opening of the valve, fuel can then flow out of the return chamber into position, the next fuel flow out of the suction chamber 8 being determined by the passage section of the

  throttling 14. Regardless of the fact that the heater

  electric fog of the thermostat 17 can be carried out in dependence on any characteristic magnitude of the motor, it is possible to

  naturally use, instead of a thermally controlled

  static 16, a valve controlled by any other means. When the valve 16 is fully open, the return chamber in position 12 is completely relieved of pressure and it is simply the return spring 21 which

  acts in the direction of the delay of the injection point. In order to obtain

  denote a determined control effect when the valve 16 is not fully open, for example a delay offset for higher rotational speeds, and to further avoid flow losses through the constriction 14 when

  high rotation speeds and open valve 16 -

  it is separated from the junction 13 by displacement of the piston

  setting tone 3, above the engine idling speed. From a sufficient pressure in the return chamber 12, the valve opens in the manner of a valve of

pressure limitation.

  In the second embodiment shown

  in FIG. 3, the injection adjusting piston 3 is

  felt on a larger scale in order to show more clearly

  a liquid flow command controlled by him. fundamental

  mentally, the operation in this example is identical to that of the first embodiment. The only difference, in addition to this first example, is that the junction 13 is controlled via an annular groove 19 provided in the injection adjusting piston 3. From this groove 19, the drilling the throttle 14 derives the current towards the return chamber 12. After the course of a predetermined portion of the race, in the direction of the advance, that is to say to the left, the annular groove 19 is separated of the

  junction 13, so that the flow of the vacuum chamber

  8 to the return chamber 12 is interrupted. Directly after this interruption, the annular groove 19 controls a

  pressure discharge bore 20, which then discharges the chamber

  Restore 12 through throttling hole 14.

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  Unlike the first example of reali-

  In this example, the return chamber 12p is relieved of the pressure, from a determined rotational speed of the motor, independently of the connection position of the pressure control valve 16. 5, here is mounted a softer spring 21, which, on start-up, causes the adjusting piston 3, after disconnection of the pressure control valve 16, to return rapidly to a position of advance of injection.

  starting point, the adjusting piston 3, which is in a position

  In this way, under the effect of the spring 21, the injection-delay device moves in the direction of advance until it abuts against the intermediate spring cup 22.

  return spring 5. The sequence of the beginning of the injection

  then corresponds again to characteristic curve I

  of Figure 2. The characteristic curve produced by the

  additional fate 21 is represented by the dashed curve

II in Figure 2.

  The characteristic curve - III shows the

  In the third exemplary embodiment shown in FIG. 4, the fuel flows continuously, through a junction conduit 13, from the chamber of the injection point setting with the valve 18 opened by the thermostat 17. 8 in the return chamber in position 12. In this junction conduit 13 is disposed a throttle 23, preferably adjustable. In normal operation, therefore the engine is hot and running at a speed higher than that of starting,

  the fuel flows out of the return chamber 12, through

  to an outlet pipe 24 in which a pressure-maintaining valve 25 is arranged. This valve 25 produces

  in the return chamber 12 a pressure acting on the piston

  your 3 in such a way that a force is produced that supports that of the spring 5. This force is superimposed on the spring force 5 and remains constant, because if it is a constant pressure and an additive connection , over the whole range of velocities., The forces acting on the piston 3 in the direction

  of the spring force by the pressure and elasticity of

  are in the case of medium and higher speeds, lower than the hydraulic forces acting on the piston 3 in the working chamber 4, so that it can result

  a corresponding displacement in advance on the speed.

  According to this third embodiment, the pressure reached in the return chamber 12 can be reduced by a second flow line 26 by means of

  a pressure control valve 27 mounted therein

  pick. The pressure control valve shown in this example of FIG. 4 functions as a thermostatic valve with a bimetal element 28 which can be heated by means of a heating resistor 29 and which is supported by a spring on a valve plug member 31 In the cold state of the heating resistor 29, the spring 30 does not press on the bi-metal element, so that the fuel flows out of the return chamber 12 through the outlet pipe

  26, before the pressure holding valve 25 opens.

  The pressure in the return chamber 12 is therefore lower than that prevailing during the normal engine speed;

  which results in a displacement of the control piston

  Instead of a bi-metal valve 27, it is possible to use a magnet-actuated or expansion-actuated valve.

or mechanically.

  In the diagram shown in Figure 5, whose coordinates correspond to those of the diagram of the

  Figure 2, curve I represents again the characteristic line

  normal tick for setting the injection point, namely

  with a hot engine, without the influence of a characteristic

  motor curve, curve IV corresponds to an advance setting of the injection point, with the operation described

  of the pressure control valve 27.

  In the fourth embodiment shown in FIG. 6, the pressure control valve 27 'is a valve controlled by an expandable member. In addition, the passage section 32 of the flow line 26 is controlled by the injection adjusting piston 3. and is closed from a determined rotational speed of the motor, i.e. that, from this speed, the forward adjustment of the type represented by the curve IV in dash of the

Figure 5 is deleted.

  A provision in principle analogous with super-

  return force position is the basis of the fifth example shown in Figure 7. The pressure control valve

  27 "here is constituted by a slide valve, whose slide

  Bucket 33 controls the flow line 26 through an annular groove 34. As soon as the slider 33 is moved, the flow line 26 is closed. This sliding is produced by a control element, such as for example an expandable material member 35, by means of the pressurized liquid which is fed from the working chamber 4 of the injection control piston 3, by driving under

  pressure 36, to a chamber 37 in which the slide

  bucket 33 with one of its front faces. On the opposite side, away from this chamber 37, the control slider 33 is loaded by a spring 38. Thus, in the manner of a safety assembly, from a determined rotational speed, the driving flow 26 is closed, so that the pressure in the return chamber 12 increases and that, accordingly, the injection start time is set to the delay.

  If one wishes to avoid a decommissioning

  As a result of the flow, a bypass line 39 of the flow line 26, which is controlled to be opened by the slider 33 and the annular groove 34, is provided, as indicated by the dashed line. this bypass pipe 39. This gives the pressure

  in the booster chamber 12 actually believes under the pres-

  sion exerted by the pipe 36, but remains lower than the pressure that would be produced by the holding valve of

pressure 25.

Claims (5)

R E V E N D I C A T IO N S   1) Fuel injection pump for internal combustion engines with a control piston causing the shift of the injection instant, displaceable piston, in its positive stroke, by a pressure proportional to the speed of rotation of the motor prevailing in its working chamber, against a return force prevailing in its return race chamber, changeable in dependencies of engine operating characteristic variables, pump characterized in that, as a restoring force, using a pressure liquid, the pressure of which is   modified according to these characteristics.   Pump according to Claim 1, characterized in that the restoring force is additionally return spring (5, 21).   3) Pump according to one of claims 1 or 2   characterized in that, for effecting the pressure change in the return chamber (12), a liquid of   pressure whose flow out of the chamber is controlled.   Pump according to Claim 3, characterized   in that the pressure liquid is directed through a foreign ment (14, 23).   Pump according to any one of the claims   1 to 4, characterized in that the maximum pressure in the return chamber (12) is limited by means of a valve pressure limiting device (16, 25).   6) Pump according to any one of the claims   1 to 5, characterized in that the inlet, and / or the outlet (13, 20, 32) in or out of the return chamber   (12) are controlled by the injection adjusting piston (3).   70) Pump according to any one of the claims   1 to 6, characterized in that in the flow management   outlet (15, 26) is provided a pressure control valve (16, 27) acting in dependence on quantities engine characteristics.   8) Pump according to Claim 7, characterized in that the pressure control valve (16, 27) operates with electric means (29).   Pump according to one of claims 7 or 8,   characterized in that the valve (16, 27) operates with temperature-dependent means, such as a regulator 9 2463272   expandable material (17) or a bi-metal element (28).   Pump according to any one of the claims   1 to 9e characterized in that the pressure liquid in the return chamber (12) is taken from a source (8) which also feeds the working chamber (4> of the piston (3).   Pump according to any one of the claims   1 to 10, characterized in that the outlet flow line (26) of the return chamber (12) is closed from a determined rotational speed of the motors by a valve (27 ") acting in dependence. of this speed,