DE19752025B4 - Method and device for regulating the fuel pressure in a fuel storage - Google Patents

Abstract

Method for regulating the fuel pressure in a fuel accumulator (7) of an injection system for an internal combustion engine (16),
wherein fuel is supplied to the fuel reservoir (7) via a feed device (2, 4, 5),
wherein via a pressure control valve (6) fuel is discharged from the fuel storage,
wherein the pressure in the fuel accumulator (7) is determined, wherein an injection quantity (MR) for the internal combustion engine is determined depending on the driver's request and on the rotational speed of the internal combustion engine (16),
wherein, depending on the injection quantity (MR), a first control signal (VCB) is determined for the feed device (2, 4, 5) with which the feed device is controlled,
wherein a second control signal (LS) for the pressure regulating valve (6) is determined as a function of the pressure in the fuel accumulator (7) and depending on a desired pressure (FUPS),
characterized,
in that, depending on the rotational speed of the internal combustion engine (16), the second control signal (LS) is corrected, with which the pressure regulating valve (6) is controlled.

Description

The The invention relates to a method for controlling the fuel pressure in a fuel storage according to the preamble of claim 1 and a controller for controlling the fuel pressure in a fuel tank according to claim 11

at Fuel injection systems having a fuel storage, is the regulation of the fuel pressure of particular importance on the one hand the fuel pressure corresponding to the dynamics of the internal combustion engine changed must and must on the other hand too high fuel pressure to energy losses and, for example for warming of the fuel tank.

Out DE 195 48 278 A1 a method for controlling a high-pressure injection engine is known in which fuel is fed from a prefeed pump to a high-pressure pump, which highly compresses the fuel and passes it on to the fuel reservoir. For controlling the fuel pressure in the fuel accumulator, the rotational speed of the prefeed pump is regulated on the one hand as a function of a precontrol value and, on the other hand, as a function of the difference between a desired value for the fuel pressure and a measured fuel pressure. In addition, a pressure control valve is provided on the fuel reservoir, which is opened at high pressure for rapid lowering of the fuel pressure.

In DE 44 46 277 A1 an injection system is described in which a demand-oriented fuel delivery is performed for a fuel storage.

Out DE 195 48 280 A1 a high-pressure accumulator injection system for internal combustion engines is known in which fuel is supplied to the fuel storage via a feed device. Fuel is removed from the fuel reservoir via a pressure control valve. The pressure in the fuel storage is determined. In this device, an injection quantity for the internal combustion engine is determined depending on the driver's request and the speed of the internal combustion engine. A control unit detects various operational output signals from various sensors and controls the injectors, the feed pump, the high pressure feed pump and the pressure control valve. In this case, in a first step, a desired value for the pressure in the rail is determined as a function of the rotational speed and the fuel quantity injected. If necessary, other variables can also be used to determine the setpoint.

The The object of the invention is based on a more accurate method for To provide regulation of the fuel pressure.

The The object of the invention is solved by the features of independent claims 1. One An essential advantage of the invention is that in the determination the first control signal for the feeder first the for the injection needed Injection amount is calculated and then from the injection quantity dependent on parameters of the feeder a control signal for the feeder is determined so that the feeder the needed Injection quantity feeds the fuel storage. This becomes the provision the needed Injection amount and the determination of the control signal for the feeder separated, creating a precise Control of the fuel pressure is enabled.

According to the invention depends on Pressure in the fuel tank and depending on a target pressure on second control signal for the pressure regulating valve determines, depending on the speed of the internal combustion engine the second control signal is corrected, with which the pressure regulating valve is controlled.

Further advantageous embodiments of the invention are specified in the dependent claims.

The The invention will be explained in more detail below with reference to the figures; show it:

1 a common rail injection system,

2 a pressure control valve,

3 the control behavior of the pressure regulating valve,

4 a schematic structure of the regulatory procedure,

5 a representation of the individual control components,

6 a dynamic control signal,

7 the fuel pressure and other control signals for an injection process.

1 schematically shows a common rail injection system in which the fuel from a fuel tank 1 via a pre-feed pump 2 , a fuel filter 3 and a throttle valve 4 to a high pressure pump 5 to be led. The high pressure pump 5 is to a fuel storage 7 connected to which a pressure control valve 6 is provided, that via a return line 12 with the fuel tank 1 communicates. The fuel storage 7 stands with injection valves 9 in conjunction, that of an internal combustion engine 16 assigned. At the fuel storage 7 is a pressure sensor 8th provided, via a signal line with a control unit 10 communicates. The control unit 10 is via a first control line 13 with the throttle valve 4 , via a second control line 14 with the pressure control valve 6 and via third control lines 15 with the injectors 9 connected.

In addition, there is the control unit 10 with a data store 17 in connection. The injectors 9 have leakage lines 11 on that to the fuel tank 1 are guided. The control unit 10 is also a pedal encoder 18 connected, which determines the driver's request. Furthermore, there is the control unit 10 with a speed sensor 19 in connection, that of the internal combustion engine 16 assigned.

The control unit 10 is still with a voltmeter 35 the supply voltage 34 connected to the supply voltage to the control unit 10 reports. There is also a condition sensor 37 the internal combustion engine 16 assigned, which determines the operating condition of the internal combustion engine such as start, idle or full load, and to the control unit 10 passes. Furthermore, a cooling system 33 for the internal combustion engine 16 provided that a temperature sensor 36 has, which measures the cooling water temperature TCO and to the control unit 10 passes.

The arrangement after 1 works as follows: The controller 10 detects the driver's request via the pedal encoder 18 and the speed of the internal combustion engine 16 via the speed sensor 19 , Depending on the driver's request and the speed of the internal combustion engine, the controller provides 10 a corresponding fuel pressure in the fuel tank 7 and controls the injection valves accordingly 9 at. In this way, the internal combustion engine 16 in response to the driver's request and the speed of the internal combustion engine, a specified amount of fuel supplied over a determined injection period.

For controlling the fuel pressure in the fuel tank 7 measures the controller 10 over the pressure sensor 8th the fuel pressure in the fuel tank and controls according to predetermined procedures that in the data memory 17 are stored, the pressure control valve 6 and the throttle valve 4 at. The amount of fuel that the fuel tank 7 is supplied in this embodiment by the opening degree of the throttle valve 4 established.

Is the high pressure pump 5 For example, in the speed controlled, so can also control the speed of the high-pressure pump 5 the amount of fuel to be controlled, the fuel storage 7 is supplied.

For example, is the prefeed pump 2 Run adjustable in the speed, it can also control the speed of the feed pump 2 the amount of fuel to be controlled, the fuel storage 7 is supplied. There are thus various control options for the fuel supply to the fuel storage 7 possible.

The invention is not limited to those in 1 illustrated arrangement of a feeder limited, which is a prefeed pump with a constant speed, a throttle valve 4 and a high pressure pump 5 includes, whose speed is proportional to the speed of the internal combustion engine, but applicable to any feeding device which supplies the fuel storage fuel.

The pressure in the fuel tank 7 is directly by an appropriate control of the pressure control valve 6 set, which depends on a first control signal from a predetermined fuel pressure in the fuel tank 7 opens and fuel over the return line 12 from the fuel tank 7 to the fuel tank 1 returns.

2 shows schematically the construction of the pressure regulating valve 6 that is a case 21 comprising a control chamber 23 limited. The pressure control valve 6 is via a supply line 20 to the fuel storage 7 connected. The supply line 20 opens via a valve opening 28 in the control chamber 23 , The control chamber 23 has a drain 24 on, over the return line 12 to the fuel tank 1 connected. The valve opening 28 is a closing element 29 assigned to that in the control chamber 23 is arranged and over a closing spring 25 against a corresponding sealing seat 22 is pressed. In addition, the closing member 29 with an anchor 26 connected to an electromagnet. The anchor 26 is a magnetic coil 27 assigned to the second control line 14 connected.

The pressure control valve 6 of the 2 works as follows: By the spring force of the closing spring 25 and by a corresponding energization of the magnetic coil 27 becomes the closing element 29 with a corresponding force against the associated sealing seat 22 pressed. Thus, a holding pressure is given, up to which the closing member 29 the supply line 20 closes. Exceeds the fuel pressure in the fuel tank 7 , ie the rail pressure the predetermined holding pressure, then the closing member 29 from the seal seat 22 lifted off and fuel flows out of the fuel tank 7 over the drain 24 and the return 12 to the fuel tank 1 back.

3 shows the rail pressure P as a function of the pulse width modulated second control signal S2, with which the controller 10 the pressure control valve 6 controls. For example, with a duty cycle of 40%, a holding pressure of 800 bar is set. This means that the pressure control valve 6 is closed to a fuel pressure of 800 bar and only opens when the fuel pressure in the fuel tank 7 exceeds the holding pressure of 800 bar.

4 shows schematically in the form of a block diagram the structure of the control method. A first regulatory block 30 controls the high-pressure side actuator, which in this embodiment, the pressure control valve 6 equivalent. A second regulatory block 31 controls the low-pressure side actuator, which in this embodiment, the throttle valve 4 equivalent.

In a further development of the invention, in addition to the throttle valve 4 the delivery rate of the pre-feed pump 2 and / or the pressure between the pre-supply pump 2 and the high pressure pump 5 for example, by a further pressure control valve and / or the delivery capacity of the high-pressure pump 5 to be controlled.

The first regulatory block 30 The engine speed N, the calculated injection quantity MF, the rail pressure FUP, the engine coolant temperature TCO, the supply voltage VB, and a state signal ES are supplied to the engine operating state. The first control block determines from these quantities 30 a third control signal HP for the high-pressure side actuator, the injection system 32 is supplied. In addition, the first control block determines 30 a pressure setpoint FUPS, preferably the second control block 31 is supplied.

The second regulatory block 31 the engine speed N, the calculated injection quantity MF, the rail pressure FUP and the supply voltage VB are supplied. The second regulatory block 31 determined from the supplied data, a fourth drive signal VC, the injection system 32 is supplied. In the injection system 32 becomes the rail pressure FUP of the fuel accumulator 7 measured and to the first and the second control block 30 . 31 guided.

5 shows the exact operation of the first and the second control block 30 . 31 , which preferably gets in the control 10 are realized. In the first regulatory block 30 From the rotational speed N, the coolant temperature TCO and the calculated injection quantity MF, a pressure setpoint FUPS is calculated in a fifth calculation unit 56 calculated.

The calculated injection amount represents the amount of fuel that is supplied to the internal combustion engine in the next injection process. The amount of fuel MF to be injected is from the control unit 10 depending on the speed and the driver's request and in dependence on a motor map that in the data memory 17 is stored, calculated. The calculation of the pressure setpoint FUPS takes place as a function of engine maps and control methods stored in the data memory 17 are stored.

The pressure setpoint FUPS becomes a seventh adding unit 57 fed. In addition, the pressure setpoint FUPS is sent to a fourth calculation unit 53 guided.

The seventh adding unit 57 In addition, the rail pressure FUP is supplied, the seventh adding unit 57 forms a pressure difference FUPD according to the following formula:
FUPD = FUPS - FBD. The seventh adding unit 57 gives the pressure difference FUPD to a linearizer unit 58 further. The linearizer unit 58 determined by known methods from the rotational speed N, the rail pressure FUP and the pressure difference FUPD a linearized control signal LS, which represents a current control intervention. The linearizer unit 58 includes a linearized PI controller whose calculation rule for the linearized control signal LS is as follows: LS (i) = LS (i-1) + K * (FUPD (i) - (1 - (TA / TN)) * FUPD (i-1)), where LS (i) is the current control intervention at time i, LS (i-1) is the previous control intervention at time (i-1), FUPD (i) is the current control difference, and FUPD (i-1) is the previous control difference is designated, wherein the control difference corresponds to the pressure difference value FUPD (i). With K is an amplification factor of, for example, 0.1% per megapascal, denoted by TN an adjustment time of, for example, 80 ms and TA a sampling time of, for example, 20 ms. The sampling time TA sets the time that lies between the time i and the time i + 1 at which the values are sampled.

The gain K equals the non-linear behavior of the pressure control valve 6 via the rail pressure FUP. In this case, the gain factor K is calculated according to the following formula: K = K0 · LF, where K0 denotes a basic gain factor with a value of, for example, 0.1% per megapascal and LF a linearization factor of 1.5, for example. The linearization factor LF is taken from a characteristic and depends on the rail pressure FUP.

The one in the linearization unit 58 calculated control intervention LS (i) then becomes a second limitation unit 59 fed. The second limitation unit 59 prevents overloading of ECU components at a high operating voltage. In addition, by the second limiting unit 59 to improve the control quality of the working range of the pressure regulator 6 to the temperature-dependent setting range of the pressure regulator 6 customized.

The limitation of the effective control intervention LS therefore preferably takes place as a function of the engine operating state ES, the battery voltage VB and the coolant temperature TCO. The setting range limits are in maps in the data memory 17 stored, which are spanned by the battery voltage VB and / or the coolant temperature TCO, with a separate map is stored for each engine operating state. The engine operating conditions are, for example, the start of the internal combustion engine, the idling or the full load operation.

The control intervention LSG limited in this way is subsequently connected to a first multiplication unit 60 guided. The first multiplier unit 60 multiplies the limited control intervention LSG with a second correction factor KB, which depends on the battery voltage VB. The second correction factor KB, which reaches a compensation of the actuating current to the corresponding actuator with respect to the supply voltage VB, either a corresponding characteristic in the data memory 17 taken, or as shown in the embodiment, in a first calculation unit 40 determined by the following approximation equation: KB = (VBR / VB), where VBR is a predetermined reference voltage and VB is the supply voltage of the actuator, wherein the supply voltage approximately in the motor vehicle corresponds to the battery voltage and the actuator in this case, the pressure control valve 6 is.

The first multiplier unit 60 determines according to the following formula a second control signal HP: HP = LSG · KB. The second control signal represents the corrected, current control intervention, via the second control line 14 to the pressure control valve 6 to be led. The second control signal is designed as a pulse-width-modulated control signal, characterized by its duty cycle, as in 3 shown, the pressure in the fuel tank 7 pretends.

The second regulatory block 31 determines a first control signal for the throttle valve 4 essentially as a function of the fuel mass flow, the at least the fuel storage to maintain the desired rail pressure and to provide the driver requested injection quantity 7 must be supplied.

This is done in a second calculation unit 42 calculated from the injection quantity MF requested and calculated by the driver and the engine speed N and the number of cylinders Z of the internal combustion engine according to the following equation the injection mass flow MFI: MFI = Z · N · MF · 0.5. The calculated injection mass MF is given in mg fuel mass per injection cycle, wherein per injection stroke only for half of the cylinder an injection is performed. The injection mass flow MFI is sent to a third multiplier unit 44 guided.

In addition, preferably a leakage mass flow MFL is dependent on the measured rail pressure FUP from a first characteristic map 41 determined and to a second multiplier unit 43 passed. The second multiplier unit 43 multiplies the leakage mass flow MFL by a first safety factor SL derived from a first data field 54 of the data memory is read out. The first safety factor SL was determined experimentally and has positive values greater than 1. The second multiplier unit 43 calculates a safety leakage mass flow ML: ML = MFL · SL according to the following formula. The value of the safety mass flow ML is sent to a first adding unit 45 guided.

The third multiplier unit 44 reads from a second data field 55 of the data memory 17 a second safety factor SI and multiplies the injection mass flow MFI with the second safety factor SI and thus receives a safety mass flow MI, the third multiplier 44 to the first adding unit 45 passes. The safety mass flow MI is calculated according to the following formula: MI = MFI · SI. The second safety factor SI is determined experimentally and has a positive value greater than 1.

The first and second safety factors ensure that more fuel is stored in the fuel tank 7 is supplied as the fuel storage 7 is removed. Preferably, the first and the second safety factor are stored in a map, which depends on the operating time of the internal combustion engine, whereby aging effects of the injection system are taken into account. Instead of the operating time and the mileage of the motor vehicle can be used.

The first adding unit 45 calculates a fuel mass flow MR according to the following formula: MR = ML + MI. The fuel mass flow MR is then a third calculation unit 47 fed. The third calculation unit 47 calculates from the fuel mass flow MR and the engine speed N a base control signal VCB. The third calculation unit determines this 47 from a delivery map, which depends on the fuel mass flow MR and the engine speed N, the Basisansteuersignal VCB. The delivery map depicts the low-pressure side delivery characteristic of the delivery device, which depends on the components used. The delivery map represents the ratio between the first control signal and the amount of fuel that is in the control of the feeder with the first control signal to the fuel storage 7 is supplied.

In the described embodiment, the low-pressure side delivery characteristic becomes substantially through the throttle valve 4 certainly, because the prefeed pump 2 at constant speed and the high pressure pump 5 at a speed proportional to the engine speed N is running. The delivery map is determined experimentally.

at Use of a speed-controlled feed pump or a speed-controlled High pressure pump is the delivery map adjust accordingly and / or in addition to the throttle valve also the prefeed pump or to regulate the high pressure pump. But also the Control signals for the prefeed pump and the high-pressure pump only after determination of the fuel mass flow from corresponding conveyor maps certainly.

The base control signal VCB becomes a fourth multiplying unit 49 fed. The fourth multiplier unit 49 multi implements the base control signal VCB with a pressure correction factor CP and determines a pressure-corrected control signal VCP according to the following formula: VCP = VCB * CP. The pressure correction factor CP is based on a second map 46 determined as a function of the measured rail pressure FUP.

The pressure correction factor CP is used because the delivery of the high pressure pump 5 depends on the rail pressure FUP and decreases with increasing rail pressure FUP. Therefore, at a higher rail pressure FUP, the throttle valve must 4 for promoting the same fuel flow into the fuel storage 7 be opened further than at a lower rail pressure FUP.

The corrected base signal VCP is applied to the fifth adder unit 50 guided. The fifth adding unit 50 sums the corrected base signal VCP and a zero point value AD and preferably a dynamic one grip VD to a first control signal VC. The zero point value AD becomes a third map 48 read out as a function of the coolant temperature TCO. The zero point value AD compensates for the change of the zero point of the throttle valve 4 depending on the temperature of the throttle valve 4 , At a higher temperature, the resistance of the throttle valve increases 4 and as a result, there is a higher actuating current for controlling the throttle valve 4 necessary than at a lower temperature. Approximately, instead of the temperature of the throttle valve 4 used the coolant temperature TCO of the internal combustion engine. In this way it is ensured that the throttle valve 4 regardless of its temperature precisely the desired degree of opening.

wobei mit VD(i) der aktuelle Wert des dynamischen Eingriffs zum Zeitpunkt i, mit VD (i – 1) der vorhergehende Wert des dynamischen Eingriffs zum Zeitpunkt (i – 1), mit FUPS(i) der aktuelle Drucksollwert, mit FUPS(i – 1) der vorhergehende Drucksollwert, mit KD ein Verstärkungsfaktor von beispielsweise 0,1%·sec/Megapascal, mit TA eine Abtastzeit von beispielsweise von 20 ms und mit T1 eine Zeitkonstante von beispielsweise 200 ms bezeichnet ist. Die Abtastzeit ist die Zeit, die zwischen dem Abtastzeitpunkt i und dem Abtastzeitpunkt i + 1 liegt.The dynamic intervention VD is performed using a fourth calculation unit 53 which represents a limited DT1 control element. The calculation rule of the fourth calculation unit 53 is set as follows:

where VD (i) is the current value of the dynamic engagement at time i, VD (i-1) is the previous value of the dynamic engagement at time (i-1), FUPS (i) is the current pressure setpoint, FUPS (i - 1) the previous pressure setpoint, with KD an amplification factor of, for example, 0.1% · sec / megapascal, with TA a sampling time of, for example, 20 ms and T1 a time constant of, for example, 200 ms. The sampling time is the time that lies between the sampling time i and the sampling time i + 1.

Preferably, the time constant T1 and the gain KD are set depending on the engine operating condition and the engine speed N. The task of the dynamic intervention is based on the fuel supply on the low pressure side to raise or lower disproportionately, especially at the transition between engine operating conditions, so as to increase the pressure or the pressure in the fuel tank 7 to accelerate.

In a fifth multiplier unit 51 the first control signal VC is preferably multiplied by the second correction factor KB, which is a compensation of the actuating current with respect to different supply voltages of the low-pressure side actuator, that is in this embodiment with respect to the supply voltage of the throttle valve 4 , causes.

The fifth multiplier unit 51 thus determines a control signal VCP according to the following formula: VCP = VC · KB. The actuating signal VCP is then a first limiting unit 52 supplied, which performs a control range limit of the control signal. The control range limit prevents overloading of the control unit components at a high battery voltage. In addition, the working range of the throttle valve is improved to improve the quality of control 4 to the temperature-dependent adjustment range of the throttle valve 4 customized.

The limitation of the effective control intervention takes place as a function of the supply voltage, which corresponds approximately to the battery voltage. The setting range limits are stored in a characteristic field, which is clamped over the supply voltage VB. The limited control signal V is from the first limiting unit 52 over the first control line 13 as the first control signal to the throttle valve 4 guided.

6 shows the pressure setpoint FUPS and the dynamic intervention VD as a function of the time t. It can be clearly seen that with the sudden increase in the pressure setpoint FUPS the dynamic engagement VD increases disproportionately and then goes back to the value zero.

7 shows the calculated injection quantity MF, the rail pressure FUP, the pressure setpoint FUPS, the second control signal S2 of the pressure regulating valve and the first control signal S1 for the throttle valve over the time t plotted. The high control quality and the rapid adaptation of the rail pressure to the pressure setpoint are clearly recognizable.

An essential advantage of the invention lies in the fact that first the fuel mass flow MR is determined and then, depending on the fuel mass flow MR, the first control signal for the low-pressure side actuator is calculated. Thus, the calculation of the fuel mass flow MR is decoupled from the calculation of the control signal. In this way, a more precise control is possible. In addition, application effort is saved because the fuel mass flow MR is calculated as a function of operating parameters and then in the third calculation unit 47 depending on a promotional map, that on the respective injection system is adapted, the corresponding first control signal is determined.

Be different feeders for supplying fuel in the fuel tank 7 used, the control unit by corresponding different delivery characteristics, in the third calculation unit 47 be taken into account, adapted to the various feeders. This allows a quick and easy adaptation of the control function to different injection systems.

Especially by the consideration the rail pressure in the pressure correction factor CP, by taking into account the zero offset by the zero point value AD and by the consideration the supply voltage VB is provided a very precise control method.

One Another significant advantage of the invention is that in the Low-pressure side regulation of the fuel supply of the rail pressure FUP not directly considered becomes. Even with the dynamic engagement VD is not the rail pressure FUP, but the pressure setpoint FUPS used to control the fuel supply to regulate. This is a rocking of the regulation of the rail pressure FUP safely avoided.

Claims (11)

Method for regulating the fuel pressure in a fuel storage ( 7 ) an injection system for an internal combustion engine ( 16 ), wherein the fuel storage ( 7 ) via a feeder ( 2 . 4 . 5 ) Fuel is supplied, via a pressure regulating valve ( 6 ) Fuel is discharged from the fuel storage, the pressure in the fuel storage ( 7 ) is determined, depending on the driver's request and the speed of the internal combustion engine ( 16 ) an injection quantity (MR) is determined for the internal combustion engine, wherein, depending on the injection quantity (MR), a first control signal (VCB) for the feed device ( 2 . 4 . 5 ) is determined, with which the feeder is controlled, wherein, depending on the pressure in the fuel storage ( 7 ) and, depending on a desired pressure (FUPS), a second control signal (LS) for the pressure regulating valve ( 6 ) is determined, characterized in that depending on the speed of the internal combustion engine ( 16 ) the second control signal (LS) is corrected, with which the pressure regulating valve ( 6 ) is controlled. Method according to claim 1, characterized in that that this first control signal dependent is corrected by the supply voltage (VB) of the feeder. Method according to Claim 1, characterized in that the second control signal is dependent on the supply voltage of the pressure regulating valve ( 6 ) is corrected. A method according to claim 1, characterized in that the first or the second control signal to a predetermined range of values ( 52 . 59 ). Method according to Claim 1, characterized in that the injection quantity for calculating the first control signal is corrected as a function of the pressure in the fuel accumulator ( 41 . 43 . 45 ) becomes. Method according to Claim 1, characterized in that the first control signal is dependent on the pressure in the fuel reservoir ( 7 ) is corrected ( 46 . 49 ). Method according to Claim 1, characterized in that the first control signal is corrected as a function of the temperature of the feed device ( 48 . 50 ). Method according to Claim 1, characterized in that a pressure setpoint (FUPS) for the fuel accumulator is determined at least from the rotational speed of the internal combustion engine, and in that the first control signal is corrected as a function of the pressure setpoint ( 50 ). Method according to Claim 8, characterized in that, depending on the change in the desired pressure value, the first control signal is corrected disproportionately (VD, 50 ). Method according to Claim 1, characterized in that the first control signal is determined from a characteristic map ( 47 ) is determined by the fuel mass flow (MR) and the speed (N) of the internal combustion engine ( 16 ) depends. Control unit ( 10 ) for controlling a fuel pressure in a fuel reservoir of an injection system, wherein the control device is designed to carry out the method according to claim 1, wherein the control device has a calculation unit ( 56 . 57 . 58 ), which depends on the pressure in the fuel storage ( 7 ) and dependent on a setpoint pressure (FUPS), the second control signal (LS) for the pressure regulating valve ( 6 ), the calculation unit ( 56 . 57 . 58 ) the second control signal (LS) depending on the speed of the internal combustion engine ( 16 ) and with the corrected second control signal the pressure regulating valve ( 6 ) controls.