DE3024883A1 - METHOD AND DEVICE FOR INJECTING FUEL IN INTERNAL COMBUSTION ENGINES, ESPECIALLY IN DIESEL ENGINES - Google Patents

Description

R. 6391
June 30, 1980

ROBERT BOSCH GMBH ₃ 7000 Stuttgart 1

Method and device for fuel injection in internal combustion engines, in particular in diesel engines

State of the art

The invention is based on a method for fuel injection in internal combustion engines according to the generic preamble of the main claim and one Fuel injection device for performing this method according to the preamble of claim 8. In one from Figure 1 of DE-OS 27 58 458 known fuel injection device, which is designed as a pump nozzle, the amount of fuel to be injected is constant Inlet cross-section and speed-dependent metering time by changing the controlled by a pressure control device Metered inlet pressure at the end of the suction stroke of the pump piston in the pump working space, and one as a function The start of delivery change controlled by operating parameters is controlled by a variable control pressure, the one Liquid buffer working in the manner of a hydraulic ram Changed, controlled in the drive. This pump nozzle works with one that is open during metering Nozzle, so that the pump working space does not have any negative pressure known from suction throttle pumps during the metering

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solution has, but as with these pumps at the end of the metering is only partially filled, so that one of the Filling-dependent change in the start of injection would occur if not the hydraulic buffer inserted into the drive would enable a change in the start of injection. Since both the quantity metering and the change in the start of delivery with working under controlled fluid pressure, a mutual adjustment is extremely complicated or difficult to carry out, because if there is a change in quantity, the start of delivery control must be updated immediately, e.g. because of an increase the upstream fuel quantity to be injected with the drive remaining the same, the start of delivery is brought forward causes.

Does this known pump nozzle not have the means for a pressure-controlled change in the start of delivery (see e.g. US-PS 3 831 846), the start of delivery or injection can only be Corrected via complex injection adjusters which are inserted into the camshaft drive and which transmit the entire torque or an injection quantity-dependent shift in the start of delivery must be accepted. goal of The invention is now a method for fuel injection and to create facilities for carrying out this process, with which an exact quantity metering the arbitrary or from engine operating parameters dependent change in the start of delivery while avoiding drive torque transferring Components and taking into account a quantity-dependent start of delivery correction can be achieved.

Advantages of the invention

The inventive method with the characterizing Features of the main claim, in addition to an exact

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th quantity metering depending on operating parameters Controlled shifting of the pumping start time through targeted use of the suction throttle pumps known, but undesirable there, quantity-dependent shift in the start of delivery. One if the one to be injected changes Fuel quantity unwanted shift of the start of delivery time is caused by a simultaneous Correction of the amount of backflow fuel avoided.

The measures listed in the dependent claims 2 to 7 are advantageous developments of the main claim specified procedure possible. Thus, in a method designed according to claim 4, the metering not influenced by pressure fluctuations, as the pump piston is much more uniform during the rest time Set pressure ratios than when metering takes place during the piston stroke movement.

As in the method specified in claims 1 to 4 the quantity metering by means of the variable inlet pressure in the pump piston during the suction stroke of at least one approximately the vacuum corresponding to the fuel vapor pressure pump working chamber takes place, can with a relative high inlet pressure range, e.g. around 50 bar, the vapor pressure of the fuel to be used as counterpressure is constant because of its very low negative pressure values Pressure value are accepted; especially when at high speeds there is a below vapor pressure sets a lying vacuum. But it can also according to the characterizing features of claims 5 or 6 of the Inlet pressure can be corrected depending on the temperature. These Correction is advantageous when the inlet pressure is not

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has such a high pressure level, e.g. around 5 bar, so that the pressure differences in the vapor pressure of diesel fuel of, for example, 20 ° C = O ₃ OOl bar compared to the vapor pressure value at 100 ° C of 0.05 bar absolute pressure can already noticeably influence the quantity metering .

The fuel injection device designed according to all of the features of claim 8 for performing the The method according to the invention enables simple, e.g. electromechanical, control of the start of delivery time. Through the adjustment device designed according to claim 9, and through the use of the to the electrical The transverse influences are the travel sensors connected to the control unit and connected to the adjustment device of delivery rate and delivery start time through precise mutual coordination of the inlet pressure that determines the inlet pressure Pressure control pulse and the control pulse determining the start of delivery time can be compensated. With a fuel Injection device according to the preamble of claim 10 is the control used to change the start of delivery the amount of backflow fuel achieved by a bevel control known from DE-AS 1 1 ^ 3 674, however, the amount of fuel to be injected is determined exclusively by the regulated inlet pressure. At the off the DE-AS 1 143 674 known fuel injection pump is the amount of fuel to be injected at a constant Fuel inlet pressure due to the changeable inlet cross-section regulated by an inlet valve designed as a throttle element. The one with a sloping control edge to limit The pump piston provided with the effective delivery stroke is also not adjusted between idle and full load, but through the inclined control edge there is an in

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end of delivery which remains constant in this area and which is limited by the maximum possible filling of the pump working space Full load set. The inclined control edge can only be used to control a starting excess with respect to their rotational position can be adjusted. In this fuel injection pump, also referred to as a suction throttle pump, results a forcibly changing start of injection depending on the delivery rate, which only goes into the Camshaft drive inserted complex and the entire torque transmitting injection phasing are corrected can.

Due to the totality of the features defined in claim 11, the otherwise when the backflow fuel is sucked in again occurring throttle losses switched off; and by the in the characterizing features of the claims 13 and l4 defined, designed as a throttle bore inlet opening the end of the metering is very quickly due to the extremely short necessary stroke of the pump piston Completion of the inlet opening, so that throttle influences the inlet opening do not come into play.

The temperature-dependent correction of the inlet pressure specified in the method claim 6 by an on the pressure control device connectable · reference pressure can be activated by a in the characterizing features of claims 15 or 16 specified device can be carried out.

drawing

Two embodiments of the implementation of the invention Process designed fuel injection

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directions are shown in the drawing and are described in more detail below. They show: FIG. 1 a simplified representation of the first exemplary embodiment with one shown in cross section as a pump nozzle trained injection pump and Figure 2 the second embodiment with a shown in cross section, piston injection pump designed as an in-line pump

Description of the exemplary embodiments

In the fuel injection device shown in Figure 1 as a first embodiment, 10 is a Mechanically driven pump nozzle referred to, which essentially consists of a drive cam lla one Otherwise not shown drive device driven piston injection pump 12 and one with this Injector 14 assembled in a common housing 13. The housing 13 is to simplify the Representation only indicated by dash-dotted lines.

A pump piston denoted by 15 is guided axially and rotatably in a pump cylinder l6, limited by its end face 17 facing away from the drive device 11 has a pump working space 18 and has a first, a axial limitation of a control groove 19 forming horizontal Control edge 20 and two second inclined control edges designed as an axial delimitation of two control surfaces 21 22, by means of which two control bores 23 located in the wall of the pump cylinder 16 at the end of the effective Delivery stroke opened and after a first, a re-intake of the backflow fuel amount permitting part of the suction stroke can be closed again. The tax

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edging 22 and the control surfaces 21 and control bores 23 are double for reasons of side pressure compensation available and can, of course, only be provided once, especially with smaller pumps will.

To correct or adjust the effective delivery stroke of the pump piston 15, the piston injection pump 12 is included an adjusting device 24 equipped in a known manner from a longitudinally displaceable control rod 25 and a Pinion sleeve 26 consists. Both parts 25 and 26 of the adjusting device 24 are provided with teeth so that in the event of a longitudinal movement of the control rod 25 caused by an actuator 27, the pinion sleeve 26 and the pump piston 15 twisted and the relative position between the discharge openings 23 and these openings during the effective Conveying stroke closing and equipped with the inclined control edges 22 control surfaces 21 changes. At the drainage openings 23, a return line 28 is connected, which is fed into an inlet line fed by a feed pump 29 31 opens. The prevailing in the feed line 31 Fuel inlet pressure p "is controlled by a pressure control device, which is shown here in simplified form by a pressure control valve 32, to a variable for measuring the delivery rate Value of preferably regulated up to about 50 bar. This compared to the inlet pressure known injection pumps very high inlet pressure also prevails in the return line 28, whereby the when the Backflow fuel throttle losses that occur are negligible can be kept small. In addition, the shut-off openings 23 can be used to reduce the influence of the throttle when locking again by the control surfaces 21

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as shaped holes with parallel to the inclined control edges 22 Boundary edges are formed. If necessary, further shut-off openings 23 can also be attached. The re-aspiration of the backflow fuel quantity can also by a dash-dotted line to be attached in the vicinity of the discharge opening 23 memory 33 and through an annular space 30 connecting the discharge openings 23 be improved. If such a memory 33 is available, then, as indicated by a dividing line 3 ^, the connection of the return line 28 to the supply line 31 can be interrupted and by a direct return 28a can be replaced to a tank 35. The pressure in the return line 28 is then reduced by a pressure holding valve 36 to a return pressure that may differ from the inlet pressure p " limited. This means that the pressures in the inlet and the return can be optimized independently of one another of the injection process can be adjusted to the most favorable values in each case.

The from the feed pump 29 with the pressure control valve 32 on the feed pressure p "regulated fuel feed line 31 opens into the pump cylinder with an inlet opening 38 16. In the drawn position of the pump piston 15, this inlet opening 38 is, however, from the one to the control groove 19 on the drive side adjoining jacket surface of the pump piston 15 is covered and only then is there with the pump working space 18 in connection when the pump piston 15 has completed its full suction stroke and in its inner or bottom dead center (BDC). The respective inner and outer or upper dead center position (TDC) of the pump piston 15 are indicated by dash-dotted lines at the distance of the piston stroke h in Figure 1 and with UT and Called OT.

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The inlet opening 38 is designed as a _{throttle bore which has a constant inlet cross section A 7} and opens into the pump cylinder 16. The inlet opening 38 is opened by the first control edge 20 of the pump piston 15 only in its inner dead center position UT and is then connected to the pump working chamber 18. In the present example, in which this inlet opening 38 is designed as a throttle bore having the inlet cross section A ₇ , it is closed again after a short part of the delivery stroke, preferably approximately the diameter of the inlet opening 38, so that no backflow influencing the metering and thus also no speed-dependent throttling can occur.

The inlet pressure p "set by the pressure regulating valve 32 for the pressure-time control used with a constant inlet cross-section A ₇ is controlled by an electrical control device 39 by means of an electromechanical intervention in the pressure regulating valve 32. The electrical control device 39, which contains an electronic control circuit, is connected to a setpoint input 41, a travel sensor 42 of the adjusting device 24 and a speed sensor 43 which emits a speed signal η. In addition, the electrical control unit 39 receives signals that are dependent on operating parameters of the engine, such as a temperature signal T (operating or fuel temperature) taken from a suitable point and other signals marked with S and e.g. the charge air pressure in the intake line of the engine, the exhaust gas temperature or mark the exhaust back pressure.

The control rod 25 actuating actuator 27 is an electromechanical actuator depending on the required

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Actuating force formed by an electromagnet, an electric servomotor or an electrohydraulic actuator and receives its control pulse I _{pB, which is} dependent on at least one operating parameter, such as the load Q or the speed η, or a correction pulse I "from the electrical control unit 39, which is described in more detail below The change in the rotational position of the inclined control edge 22 and thus the end of delivery that can be achieved by the adjustment device 24 does not determine the fuel injection quantity Q _{F here,} but rather serves to change the delivery start time according to the invention.

The supply pressure p ″ required for regulating the feed pressure p ″ which is variable for the metering of the quantity and regulated by the pressure regulating valve 32 Means are simplified by one controlled by the electrical control unit 39 by means of the pressure control pulse I ″ Actuator 44 shown, through which the biasing force of a pressure control spring 45 of the pressure control valve is changed.

The controlled fuel metering thus takes place with a constant inlet cross section A "by means of the variable inlet pressure p" determined by the pressure control pulse I "and regulated by the pressure regulating valve 32. The constant inlet cross-section A ₇ is formed by the inlet opening 38, and the fuel inlet pressure p "works against a vapor pressure of the fuel in the pump working chamber 18 at the end of the suction stroke, which at a high inlet pressure of, for example, up to 50 bar with its extremely low absolute pressure values of 0.001 bar at 20 ° C and 0.05 bar at 100 ° C need not be measured exactly, but as an absolute vacuum with zero bar when determining the pressure control pulse

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I _{7 is} taken into account. If, for example, the operating or fuel temperature needs to be taken into account at a lower inlet pressure, then this is taken into account by means of the temperature signal T in the electrical control device 39 when determining the pressure control pulse I ". In this way, the inlet pressure p ₇ can be corrected, for example by changing the pretensioning force of the pressure regulating spring 45 of the pressure regulating valve 32 via the actuator 44 activated by the electrical control unit 39.

Another possibility of adapting the inlet pressure p ₇ is that a chamber 46 of the pressure control valve 32, which contains the pressure regulating _{spring 45 and is sealed off from the outside, is subjected to a reference negative pressure p R} via a line 47, which is generated by a negative pressure source 49 detailed in FIG will.

The pump working chamber 18, which is closed in the direction of the injection nozzle 14 by a pressure valve 52, is to avoid To keep harmful dead space as small as possible, but it must be so large that both the fuel injection quantity as well as the amount of fuel serving to shift the start of injection can be stored upstream.

The second embodiment shown in Figure 2 is different differs from the first embodiment shown in Figure 1 essentially only with respect to the design the injection pump used. Identical parts are therefore labeled identically and parts that differ from each other with an index line Mistake.

In the second embodiment it is used as a piston injection pump

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an in-line injection pump 12 'is used, shown in FIG. 2 in a cross section passing through a pump element is shown. The pump element shown is oil via a pressure line to the injection nozzle attached to the engine cylinder 14 'connected, the other pump elements, not shown, supply corresponding injection nozzles of the other engine cylinder. Since all pump pistons 15 'via a common control rod 25' of the adjustment device 24 ' are coupled to each other, only one control unit 39 is necessary for the entire fuel injection device, which supplies the electromechanical actuator 27, which actuates the control rod 25 ', with the control pulse I ™, from the travel sensor 42 of the actuator 27 receives a travel signal, is connected to the setpoint input 4l and also the pressure control pulse I "for the actuator 44 of the pressure control valve p / i

32 generated.

The drive cam 11a of the drive device 11 is attached to a camshaft 62 which is coupled to the feed pump 29 as well as to an auxiliary piston pump 49 serving as a vacuum source via a drive shaft 63 indicated by dash-dotted lines and which carries the speed sensor 43. This auxiliary piston pump 49, driven together with the injection pump 12 ', generates the reference pressure p _R in the chamber 46 of the pressure control valve 32, which, in the same way as the vapor pressure of the fuel in the pump working chamber 18 of the injection pump 12', changes depending on the operating temperature or fuel temperature T. and thus the pressure control is corrected depending on the temperature. This arrangement can be implemented most effectively when the pressure regulating valve 32 is designed as a diaphragm pressure regulator.

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_{To generate the reference pressure p R} which serves to correct the inlet pressure p R, the chamber 46 of the pressure regulating valve 32 containing the pressure regulating spring 45 is via the suction line 47 with a working chamber 48 which is driven parallel to the injection pump 12 'or at the same time with the feed pump 29 and is driven by the feed pump 29 supplied with fuel, serving as a vacuum source auxiliary pump 49 connected. The suction line 47 contains a check valve 51 that opens in the direction of the working chamber 48 and can be adjusted to a corresponding partial filling of its working _{chamber 48 in order to generate the reference negative pressure p R corresponding to the fuel vapor pressure occurring during each suction stroke of the injection pump 12.} This setting is carried out by turning the pump piston 50, which is provided with an inclined end face 53. The use of such an auxiliary pump, formed here by the piston pump 49, is relatively expensive in terms of effort and is intended for extremely precise metering and, as can be seen from the dashed lines, only shown as an alternative solution.

In both of the described exemplary embodiments, the inlet opening 38, which is designed as a throttle bore, is separated from the first Controlled control edge 20, which is opposite to the inclined control edges 22 as an axial delimitation of the control groove 19 is trained. The inlet opening 38 can also, if the pump design allows this, based on the position of the discharge openings 23 are arranged closer to the pump working space 18 and from a horizontal, from the end face 17 of the pump piston 15 or 15 'formed control edge in the bottom dead center position UT of the pump piston 15 or 15 'opened and again after the start of the pressure stroke be completed. So that in this case the inlet and

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The second control edges 22 towards the drive device 11 can not be too close to one another be offset in the axial direction.

Another variant of the invention, only indicated in FIG. 1 Fuel injection device is to be switched off which may occur due to the throttling losses when the backflow fuel flows out and is sucked in again Quantity scatter at the discharge openings 23 with each a check valve 64 is provided, and via the inlet opening 38 is then in the pump working chamber 18 both the to be injected as well as an amount of fuel replacing the return flow amount of fuel upstream. In Figure 1 is only one of the check valves 64 in phantom in front of one of the Shut-off openings 23 are shown.

The following is the mode of action of the invention Fuel injection device based on that shown in FIG first embodiment described:

If the pump piston 15 continues its delivery stroke from the position shown in FIG. The end of delivery takes place relatively late in the drawn rotational position of the pump piston 15 because only a small amount of return flow Qp is diverted. The return flow ends in UT and the return flow _{quantity Q R} is sucked back into the pump working chamber 18 via the shut-off openings 23 at the beginning of the suction stroke until the inclined control edges 22 close the shut-off openings 23. With further suction

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stroke up to the BDC position of the pump piston 15, the pump working chamber 18 is placed under negative pressure, which corresponds approximately to the vapor pressure of the fuel, and is within the rest time controlled by the drive cam 11a when the inlet opening 38 is fully open and the pump piston 15 is at BDC , metered the amount to be injected controlled by the regulated inlet pressure p ". After the rest time, the pressure stroke of the pump piston 15 begins by first compressing the cavity in the pump working chamber 18, which is under vapor pressure and its volume is dependent on the upstream fuel injection quantity and the re-sucked back flow fuel quantity, until the start of delivery and the fuel placed under injection pressure the Pressure valve 52 opens and fuel arrives at injection nozzle 14 and from there into the working cylinder of the engine. The injection is ended when shortly after the position of the piston 15 ₃ shown in FIG. The control of the end of delivery by changing the rotational position of the inclined control edges 22 or by the actuating movement of the control rod 25 caused by the electromechanical actuator 27 does not serve to regulate the delivery rate, as is the case with known pumps, but rather determines the delivery start time through the reverse flow fuel quantity Q _R which is diverted and sucked in again. If the pressure control pulse I "

of the control unit 39 controlled inlet pressure p _z in the inlet line 31 to control a different fuel injection z amount changed, then the control _{rod 25 is tracked by the correction pulse I K} via the actuator 27 with a correspondingly adjusted control speed and corrected the return fuel amount so that the delivery rate

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starting time remains constant. However, if the delivery start time is to be changed as a function of the speed η or as a function of other operating parameters S while the injection quantity remains the same, then a different rotational position of the pump piston 15 is set by the adjustment device 24. For precise control of this rotational position, the adjustment device 24 provided with the electromechanical actuator 27 is provided with the travel sensor 42 which supplies a travel signal to the electrical control unit 39, which is only indicated in FIG or otherwise acting known displacement encoder is formed. With a constant feed cross section A ″, the upstream fuel quantity is dependent on the _{feed pressure p 7, which is regulated taking into account the speed.} For this purpose, the inlet pressure p "is regulated to the required value by the pressure regulating valve, which if necessary still depends on the fuel temperature T or on the temperature-dependent change in the vapor pressure in the pump working chamber l8 by a corresponding correction of the pressure control signal I" or by corrective action on the pressure regulating valve 32, for example by means of the auxiliary piston pump 49 (see FIG. 2).

To carry out the method according to the invention, not only the pump nozzles 10 or the injection pump described are required 12 can also be used, but the process can also be used with slide valve-controlled injection pumps or used in distributor injection pumps. Common to all possible applications is the inventive concept that for metering the parts evacuated in the suction stroke Upstream fuel

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amount of the inlet cross-section kept constant and only the inlet pressure is controlled electrically, that also a shift in the delivery start time controlled as a function of operating parameters through a change the amount of backflow fuel is reached and that finally when the amount of fuel to be injected changes an unwanted shift in the start of delivery time due to a simultaneous occurrence of the Fuel metering dependent correction of the return fuel amount is avoided. Determine the speed-dependent amount when the backflow fuel is sucked in again Opening time of the inlet opening and the regulated inlet pressure the amount of fuel to be injected. When the spill opening is blocked by a valve, re-suction the amount of backflow fuel is prevented by regulating the inlet pressure as well as the amount to be injected and an amount of fuel that replaces the amount of fuel flowing back is metered.

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Claims (1)

R. 6391
June 30, 1980 Ks / Wl ROBERT BOSCH GMBH, 7000 Stuttgart 1 Expectations / l. ! "Method for fuel injection in internal combustion engines, especially in diesel engines, in which at least one of a cam-driven piston injection pump Fuel injection quantity delivered to an injector with constant inlet cross-section and speed-dependent metering time by changing the pressure control device regulated inlet pressure at the end of the suction stroke of the pump piston into the pump working space, the pump working space at the end of delivery by shutting off a return flow fuel quantity is relieved of pressure in a return line and the start of delivery changes depending on operating parameters is, characterized in that the shift of the delivery start time controlled as a function of operating parameters by changing the amount of return fuel that is achieved on at least one part of the suction stroke of the pump working chamber is placed under negative pressure, and that when the fuel injection quantity changes to avoid an unintentional shift in the delivery start time, the return flow fuel quantity is the same. 130066/0029 ORIGINAMNSPECTED - 2 - R. 6391 timely depending on the amount of fuel metered is corrected. 2. The method according to claim 1, characterized in that on a first, the Absteuerhub corresponding part of the Suction stroke, the amount of backflow fuel is sucked in again and on the remaining part of the suction stroke under negative pressure is set, and that only the fuel injection quantity is metered by changing the inlet pressure will. 3. The method according to claim 1, characterized in that prevents the return flow of fuel from being sucked in again and that by changing the inlet pressure, both the amount of fuel to be injected and the amount of fuel flowing back replacing fuel is metered. 4. The method according to any one of claims 1 to 3j, characterized in that that the fuel metering at the end of the suction stroke, predominantly takes place within a rest time keeping the pump piston in its inner dead center position. 5. The method according to any one of claims 1 to 4, characterized in that that the inlet pressure as a function of a 130066/0029 - 3 - R. 6391 Operating temperature j preferably the fuel temperature, is corrected. 6. The method according to any one of claims 1 to Ί, characterized in that that 'the regulated inlet pressure to take into account the temperature dependence of the back pressure in the Effective vapor pressure in the pump working space is corrected by a reference pressure which can be switched to the pressure control device will. 7. "Method according to one of claims 1 to 6, characterized in that that both the change in the inlet pressure and the change and / or correction of the return fuel quantity be controlled or regulated electrically. 8. Fuel injection device for carrying out the Method according to Claim 1 or 2, with an inlet pressure which generates the inlet pressure regulated by the pressure regulating device Feed pump, with one which can be closed during the feed stroke of the pump piston and has the constant feed cross section Inlet opening to the pump work space and with a pump work space opened at the end of delivery the return line connecting the spill opening, thereby characterized in that the piston injection pump (12, 12 ') for -H- 130066/0029 ORIGINAL INSPECTED - 4 - R. 6391 Correction of the delivery end of the pump piston (15 ₃ 15 '), which determines the amount of backflow fuel, is provided with an adjusting device (24j 24') by means of which the relative position between the control opening (23) and a control surface (21) closing this opening during the delivery stroke can be changed . 9. Device according to claim 8, characterized in that the "adjusting device (24, '24'") can be actuated by an electromechanical actuator (27) which is used to shift and / or correct the delivery start time by one of at least one operating parameter (Q ₅ n , S) dependent control pulse (I _pR3 I ") of an electrical control device (39) can be controlled that a setpoint input (41) and a travel sensor (42) of the adjusting device (24, 24 ') are connected to the control device (39), and that the control unit (39) sends a pressure control pulse (I ") which determines _{the inlet pressure (P z) to an electromechanical one} ρΛ Pressure regulating actuator (44) of the pressure regulating device (32) emits. 10. Device according to claim 9, in which the pump piston, guided in a pump cylinder of the injection pump, has a first, closing the inlet opening during the delivery stroke 130066/0025 ORIGINAL INSPECTED - 5 - R. 6391 Control edge and is provided with a second control edge designed as an axial delimitation of the control surface, by means of which the control opening in the wall of the pump cylinder can be opened at the end of the delivery stroke, characterized in that the second control edge is an inclined slope to the longitudinal axis of the pump piston (15) Control edge (22) is formed by means of which the control opening (23) after the first, corresponding to the control stroke and re-aspirating one of the backflow amounts of fuel corresponding fuel quantity permitting part of the Suction stroke is controllable again. 11. Device according to claim 9, in which the pump piston guided in a pump cylinder of the injection pump is provided with a first control edge that closes the inlet opening during the delivery stroke and with a second control edge designed as an axial delimitation of the control surface, by means of which the control edge in the wall of the pump cylinder The control opening located at the end of the delivery stroke can be opened, characterized in that the second control edge is designed as an inclined control edge (22) inclined to the longitudinal axis of the pump piston (15). 18) preventive valve (64) 130066/0029 - 6 - R. 6391 can be closed, and that the inlet pressure (p _z ) determining pressure control pulse (I ") both the fuel p /, injection quantity as well as a fuel quantity replacing the return flow fuel quantity can be determined (FIG. 1). 12. Device according to claim 10 or 11, in the case of the plague the amount of backflow fuel, the rotational position of the pump piston by the adjusting device having a control rod is changeable, characterized in that the electromechanical Actuator (27) engages the control rod (25, 25 ') and one of the moves when the rotational position is changed Parts with the travel sensor (42) is provided. 13. Device according to one of Claims 8 to 12, characterized in that the inlet opening is designed as a _{throttle bore (38) which has the constant inlet cross section (A 17} ) and opens into the pump cylinder (16). lh. Device according to one of Claims 10 to 13 , characterized in that the inlet opening (38) is opened from the first control edge (20) of the pump piston (15 ₃ 15 ') only in its inner dead center position (UT) and with the pump working space (l8) is related, and that they 13006B / 0029 - 7 - R- 6391 already after a short part of the delivery stroke, preferably about the diameter of the inlet opening (38) is completed again. 15. Device according to one of claims 8 to 14, for performing the method specified in claim 6, characterized in that the reference pressure (P _R ) from a parallel to the injection pump (12 ') driven and supplied by the feed pump (29) with fuel Auxiliary pump (49) is generated, the working chamber (48) of which is connected via a suction line (47) containing a check valve (51) to a chamber (46) of the pressure control device (32) which influences the pressure control (FIG. 2). 16. Device according to claim 15, characterized in that the auxiliary pump is designed as a piston auxiliary pump (49) which is used to generate the reference pressure (p _R ) proportional to the fuel vapor pressure in the pump working chamber (18) of the injection pump (12 ') to a partial filling of its working chamber ( 48) is adjustable. 130066/0029