DE102007028960A1 - High-pressure pump for fuel system of internal combustion engine, has intake valve device, which is brought by actuation device to certain position or held in certain position - Google Patents

Abstract

The high-pressure pump (9) has an intake valve device (11), which is brought by an actuation device to a certain position or held in a certain position. The intake valve device has a valve needle and a valve body and the valve needle has a hydraulic driver. The hydraulic driver executes force acting in opening direction on the valve needle by fuel flowing from the intake valve device into the conveyor space. An independent claim is also included for a method for operating a high-pressure pump for a fuel system of an internal combustion engine.

Description

State of the art

The The invention relates to a high-pressure pump for a fuel system an internal combustion engine having an intake valve device which by means of an actuator forcibly in a certain position and / or in a certain position can be held. It further relates to a method of operation such a high-pressure pump.

From the EP 1 701 031 A1 a shaft driven high pressure pump is known having such inlet valve means. This inlet valve device has a coil for electrical actuation. A disadvantage of this high-pressure pump is that a component of relatively high mass is moved when the inlet valve device is actuated. This relatively high moving mass leads to a time-delayed opening and closing of the inlet valve device, so that in particular at high rotational speed of the shaft relatively high intake and Rückströmverluste occur that worsen the delivery of the high-pressure pump.

A method for controlling such a valve device is known from DE 10 2004 016 554 A1 known. In addition, further driving methods, for example, from the publications DE 10 2004 01 91 52 . DE 103 58 858 and DE 10 2004 03 2721 known.

Disclosure of the invention

task The invention is a high pressure pump with adjustable flow rate to provide for a fuel system of an internal combustion engine, in particular at a high operating frequency of the pump piston even more effective and reliable, and yet simple and inexpensive to produce.

These Task is achieved by a high pressure pump with the features of the claim 1 solved. The task is also performed by a procedure solved with the features of claim 9.

advantageous Further developments are mentioned in subclaims. For the invention important features also go from the following Description and the drawing, the features alone or in different combinations may be important without being explicitly mentioned again.

Because by the hydraulic driver the movement of the valve needle in the opening direction is supported (hydraulic Support), can be used by the operating device chosen force applied to the valve needle less become. This allows the actuator to be more compact, easier and run more cheaply. Thereby that the valve body and the valve needle as separate Components are executed, needs to open during the suction stroke the inlet valve only a relatively small mass to be moved since it is sufficient, at first only the valve body to move while the movement of the valve needle in the opening direction slower and / or done later can. As a result, a good delivery of the high-pressure pump is achieved. The hydraulic support has a particularly advantageous effect at high pump speeds, that is at high operating frequencies a pump piston and the inlet valve device, since there available operating time of the valve needle accordingly is short.

Because of The hydraulic support can be the magnetic circuit of the Coil and the magnet armature are designed to be relatively small, with a comparatively high-impedance coil can be used. This again has the advantage that electric currents and thus ohmic power losses both in the coil as well in a final stage to their control are relatively low, so the power amplifier is relatively inexpensive can be.

in this connection it is particularly preferred that the driver in from the delivery room into the inlet valve device effluent fuel - if this during a delivery stroke from an actuator forcibly kept open - one against the opening direction acting force exerted on the valve needle, the lower is as the fuel flowing in on the valve needle in the opening direction acting force. This ensures that a force exerted by the actuator force to keep open the already opened inlet valve device is relatively low. The actuating device or devices for driving the actuator therefore particularly simple and inexpensive become.

in this connection can be provided that a limited by the driver free Cross sectional area of a fuel flowed through Area by moving the valve needle in the opening direction enlargeable is. Then one of them is flowing through the valve device Fuel exerted on the driver of the valve needle Flowing force is lower, the more the valve needle moves in the opening direction becomes. Thus, it is easily achieved that by the Delivery chamber outflowing and into the valve device returning fuel against the opening direction acting force on the valve needle is relatively low.

It can be provided that the driver with the valve needle in one piece connected is. A one-piece, the driver and the Valve needle comprehensive component can be produced particularly easily become.

It It is particularly preferred that the actuating device is electromagnetically actuated. An electrical control Namely, the intake valve device allows operating the high pressure pump with commonly used electronic control or regulating devices, and in an electromagnetic Actuator are the above advantages particularly succinct.

It can be provided that the high-pressure pump is a return spring has, which acts on the valve needle, that on the valve needle a Force counter to the opening direction acts. In this way the closing of the valve device is accelerated, so that the delivery rate of the high pressure pump further increases becomes.

Of Furthermore, it can be provided that the high-pressure pump has a first the valve body facing stop which is connected to a first of the Valve body opposite counter-stop of the valve needle cooperates, and / or a second from the valve body facing away from the stop, with a second valve body facing counter-stop of the valve needle cooperates, has. On This way, the stroke of the valve needle is limited, so that the times for opening and closing the valve device be further shortened and a wear-resistant Operation of the high-pressure pump is ensured.

in this connection is particularly preferred that the first stop and the second Stop as a respective orthogonal to a longitudinal axis the valve needle arranged stop surface of a first and a second guide member are formed and the valve needle arranged between the two guide elements Stopper portion has, at which the first and the second Counter stop as each orthogonal to the longitudinal axis of the Valve needle arranged counter stop surface are formed. The stops for limiting the stroke of the valve needle can be realized in a particularly simple manner. Furthermore can be between the stopper section and the stopper that is between the stopper portion and the valve body is arranged, be easily attached a return spring.

By the energization of an electromagnetic actuator with a reduced average current after the expiration a suit duration, according to the method of the invention, is achieved that a mean driving power relatively is low. This also reduces the power loss and Thus, the heat on the coil, so that only simple means for heat dissipation must be provided. Likewise, a cooling device for a drive circuit the coil smaller and thus easier and cheaper will be realized.

in this connection can be provided that the energization of the actuator with the reduced average current through applying the actuator with a pulse width modulated Signal and / or performed using a current control becomes. By using a pulse width modulated signal can realized a particularly low-loss control of the coil while using a current control the Strength of the current supply particularly precisely determined can be.

in this connection It is preferable that the holding period be made using a set value and an actual value of a pressure in a fuel rail is determined. Because this represents a particularly simple and reliable Method for stabilizing the pressure in the fuel manifold represents.

Brief description of the drawings

following will be exemplary embodiments of the present invention Invention with reference to the accompanying drawings closer explained. Like elements bear the same reference numerals and are usually described only once in detail. In the Drawing show in a schematic representation:

1 a fuel system of an internal combustion engine with a high-pressure pump and a quantity control valve;

2 the high-pressure pump according to the invention 1 in the suction phase with no-flow quantity control valve;

3 the high pressure pump off 1 in the funding phase with energized quantity control valve;

4 the high pressure pump off 1 in the delivery phase with no-current menue control valve;

5 the time course of the piston stroke, stroke of the solenoid valve, stroke of the valve needle and the associated current and voltage curves.

6 a sectional side view of an inlet valve device of a first detailed embodiment of a high according to the invention pressure pump;

7 a detail of the inlet valve device 6 with closed inlet valve;

8th a representation similar 7 with the inlet valve open;

9 a representation similar 7 a second embodiment of a high-pressure pump according to the invention;

10 a valve needle of an intake valve device according to the first embodiment; and

11 a valve needle of an intake device according to the second embodiment.

embodiments the invention

1 shows a fuel system 1 an internal combustion engine 19 , A prefeed pump 3 is on the one hand with a fuel tank 5 and on the other hand via a line 7 with a high pressure pump 9 connected. The high pressure pump 9 includes an inlet valve device 11 , which in the following also as quantity control valve 11 referred to as. The high pressure pump 9 is over a line 13 to a fuel manifold 15 connected to the injectors 17 an internal combustion engine 19 are connected. At the fuel manifold 15 there is a pressure sensor 21 for detecting a pressure p in the fuel rail 15 , The internal combustion engine 19 has a speed sensor 23 for detecting a rotational speed n of the internal combustion engine 19 on. In addition, the fuel system points 1 a control unit 25 on that with a temperature sensor 27 for detecting a temperature T is connected. At the control and regulating device 25 it is a programmable control and regulating device, which is a storage medium 29 on which a program for calculating a manipulated variable S for controlling the quantity control valve 11 is stored.

When operating the fuel system 1 pumps the prefeed pump 3 one in the fuel tank 5 existing fuel over the line 7 to the high pressure pump 9 and acts on the fuel with a prefeed pressure. The quantity control valve 11 serves to influence the flow rate of the high-pressure pump 9 , The high pressure pump 9 pressurizes the required delivery rate with a relatively high pressure p and delivers it via the line 13 into the fuel manifold 15 at which the fuel passes through the injectors 17 in combustion chambers an internal combustion engine 19 is injected. The quantity control valve 11 is from the control or regulating device 25 driven. The control or regulating device 25 determined using the pressure sensor 21 the pressure p, using the temperature sensor 27 the temperature T and using the speed sensor 23 the speed n and takes these values p, T, n in the control of the quantity control valve 11 In other words, in an embodiment not shown, the detection of the temperature T can be dispensed with and the temperature sensor can be dispensed with 27 be omitted.

In the 2 to 4 is a schematic representation of the high pressure pump 9 with quantity control valve 11 shown.

The high pressure pump 9 includes a piston 31 that of a cam 33 is driven so that it reciprocates and thereby the volume of a delivery chamber 37 alternately reduced and enlarged. The quantity control valve 11 has an inlet valve 35 with a valve body 39 and a sealing seat 43 on. An inlet valve spring 41 presses against an opening direction (arrow 51 ) of the inlet valve 35 against the valve body 39 , About the line 7 can be one upstream of the sealing seat 43 located area 49 Fuel can be supplied, and the fuel can be out of this range 49 over the opened inlet valve 35 in the pump room 37 the high pressure pump 9 reach. For actuating the valve body 39 of the inlet valve 35 is a valve needle 45 with a hydraulic driver 47 , a spring 53 on the valve needle 45 one against the opening direction 51 acting force exerts, and one with the valve needle 45 connected armature 55 that of a coil 57 is surrounded, provided. Downstream of the pump room 37 is located between the pump room 37 and the line 13 as a check valve 59 trained exhaust valve 59 for preventing backflow of the high-pressure fuel.

2 shows the high pressure pump 9 in a suction phase. The piston moves 31 for example, due to the force of a spring not shown down. Due to the pressure difference between the area 49 and the pump room 37 the valve body moves away 39 against a spring force of the inlet valve spring 41 from the seal seat 43 , The fuel flows through the pipe 7 over the open inlet valve 35 that is through the area 49 , in the pump room 37 , Because the hydraulic driver 47 in the area through which the fuel flows 49 is located, the hydraulic driver during the suction phase undergoes a hydraulic force in the opening direction 51 acts. Because the hydraulic driver 47 and the valve needle 45 connected to each other, the hydraulic force also acts on the valve needle 45 , At the same time the Ven tilnadel 45 a spring force of the spring 53 , which of the opening direction (arrow 51 ) is opposite. Depending on the design of the high-pressure pump 9 and depending on the speed of the cam 33 The hydraulic force may be greater or less than the spring force of the spring 53 be. Is the hydraulic force greater than this spring force - for example, at a high suction speed of the piston 31 - becomes the valve needle 45 together with the valve needle 45 connected magnet armature 55 to the right, ie in the opening direction 51 emotional.

At the beginning of the suction phase is the coil 57 initially energized, but it is before the start of a delivery stroke of the piston 31 energized (see 3 ). During the delivery stroke of the piston 31 this moves upwards, which is in the conveyor room 37 sucked fuel is thus expelled again. Once the coil 57 energized, it builds up a magnetic field and pulls the magnet armature 55 in the opening direction 51 against the spring force of the spring 53 at. The valve needle 45 holds in this way the inlet valve 35 forcibly also during the delivery stroke of the piston 31 open for a desired period of time. During this period, fuel may leak through a gap 61 that is between the seal seat 43 and the valve body 39 is present, on the low pressure side, that is in the line 7 , flow back.

During the delivery stroke of the piston 31 becomes the coil 57 off. The magnetic force is reduced, so that due to the spring force of the spring 53 the magnet armature 55 together with the valve needle 45 to the left, that is opposite to the opening direction 51 moved (see 4 ). Due to the pressure difference between the delivery chamber 37 and area 49 and due to the force of the intake valve spring 41 closes the inlet valve 35 , and one in the pump room 37 contained fuel quantity is via the check valve 59 on the high pressure side, that is over the line 13 into the fuel manifold 15 , promoted.

In 5 are the piston stroke x _K , the stroke x _{N of} the valve needle 45 of the quantity control valve 11 , the stroke x _{EV of} the valve body 39 of the inlet valve and the courses one at the coil 57 applied voltage u and one through the coil 57 flowing current i shown. The piston stroke x _K has the value zero, if the delivery chamber 37 has a maximum volume. The stroke x _{N of} the valve needle 45 as well as the stroke x _{EV of} the valve body 39 then each have the value zero, if the valve needle 45 or the valve body as far as due to the structure of the quantity control valve 11 possible against the opening direction (arrow 51 ) are positioned (inlet valve 35 closed).

Out 5 It can be seen that at the beginning of the suction phase at time t _1, the inlet valve 35 opens. Although until the time t _2, the quantity control valve 11 is not energized, also moves the quantity control valve, that is, the valve needle 45 , due to the hydraulic support (stroke x _N ). With the onset of energization experienced the armature 55 and thus also the valve needle 45 an increasing magnetic force acting in the direction of the hydraulic force and against the spring force of the spring 53 , ie in the opening direction 51 , works. Even during the suction phase, the quantity control valve 11 have tightened, that is, the valve needle 45 must be in the opening direction 51 have moved so much that they are on the valve body 39 seated, so at the beginning of the delivery stroke of the piston 31 at time t _3, the inlet valve 35 can be kept open. The tension for quickly tightening the magnet armature 55 must have a relatively high rms value. Im in 5 shown exemplary course of the voltage u, a constant voltage pulse over the duration t _{A is} applied. Depending on how strong the hydraulic support acts, the tightening phase t _A can be selected shorter or a lower voltage u can be applied.

Is the magnet armature 55 attracted, the current i can be reduced to hold. This is done with the help of a PWM signal or a current control. During the duration t _H , the current i is reduced so much that the magnetic force for keeping open the inlet valve 35 sufficient. The magnetic force must be greater than the sum of the spring force of the spring 53 , the valve body 39 of the inlet valve 35 acting flow force and the spring force of the intake valve spring 41 , With reverse flow direction from the time t ₃ (start of the delivery stroke) acts on the hydraulic driver 47 a directed against the magnetic force hydraulic force. This hydraulic force points during the open state of the intake valve 35 a relatively small amount because of a gap 61 between drivers 47 and valve seat 43 in valve direction shifted in the opening direction 45 is relatively large.

To close the inlet valve 35 At time t _4, the current i is extinguished by applying a negative voltage u to the coil during an erase time t _L 57 is created. The magnetic force is thereby reduced, and the inlet valve 35 closes at time t ₅ , so that now the remaining amount of fuel in the delivery room 37 the high pressure pump 9 compacted into the pipe 13 is funded (funding phase). After the expiration of the deletion time t _L , ie at the time t ₆ , the voltage u is turned off.

The control of the flow rate via the pressure p in the fuel rail 15 , If less fuel is delivered than via the Einspritzven tile 17 is injected, the pressure p in the power manifold decreases 15 , By comparing the pressure p with one of the setpoint pressure p _s , the holding time t _{H is} recalculated. In the case of too low actual pressure, the holding time t _{H is} shortened, so that the delivery phase starts earlier and a larger amount of fuel in the fuel rail 15 is pumped.

6 shows the structure of the quantity control valve 11 , The inlet valve 35 has a pipe socket-shaped counterpart 65 with the sealing seat 43 , the valve body 39 , the inlet valve spring 41 and a penholder 71 on. The counterpart 65 has radial opening cross sections 73 and an axial flow channel 75 on. Through the opening cross sections 73 and the flow channel 75 can the fuel from the pipe 7 to the seal seat 43 and to the valve body 39 of the inlet valve 35 reach. Furthermore, the quantity control valve 11 a connector 77 on, with which the counterpart 65 firmly connected (for example, pressed or welded) is. At his from the inlet valve 35 opposite side has the connector 77 an area 79 on that with the connector 77 an antipole for the armature 55 forms. The magnet armature 55 is with the valve needle 45 firmly connected by a press connection. Likewise, the hydraulic driver sits 47 firmly on the valve needle 45 , It is located with the intake valve closed 35 in the flow channel 75 the counterpart 65 ,

The valve needle 45 is in a guide plate 81 and in a guide sleeve 83 slidably mounted. The guide plate 81 has a first in 6 right-pointing stop surface 85 on, and the guide sleeve 83 has a second in 6 left-facing stop surface 87 on. The valve needle has a stopper portion 89 in the form of a covenant 89 on, between the stop surfaces 85 and 87 is arranged. One at the guide plate 81 facing side of the covenant 89 existing first counter stop surface 91 acts to limit the stroke of the valve needle 45 against the opening direction 51 with the first stop surface 85 the guide plate 81 together. At his the guide sleeve 83 facing side, the federal government 89 a second counter-attack surface 93 to limit the stroke of the valve needle 45 in the opening direction 51 on. The feather 53 is in the guide sleeve 83 arranged and pushes against the opening direction 51 against the valve needle 45 ,

7 shows a section of the quantity control valve 11 with inlet valve 35 in a resting position. The feather 53 ensures that the valve needle 45 with the first counter stop surface 91 of the federal government 89 at the first stop surface 85 the guide plate 81 is applied. The inlet valve 35 is closed, and the valve body 39 lies on the seal seat 43 on. Between the valve body 39 and the valve needle 45 There is a minimal gap.

8th shows the in 7 shown section during the suction phase. The flow is as a dotted line (arrow 95 ). When sucking, the inlet valve opens 35 automatically. In addition, acts on the hydraulic driver 47 a flow force (arrow 97 ), characterized by the flow around the driver 47 in the flow channel 75 results. Since the direction of flow reverses during the backflow phase, as low a flow force as possible is desirable during this phase. This is achieved in the illustrated exemplary embodiment in that the gap 61 in the direction of opening moving valve needle 45 , in particular when forcedly held open inlet valve 35 , is greater than in opposite to the opening direction 51 moving valve needle 45 , especially when the inlet valve is closed 35 , Notwithstanding this, the driver in the open state of the quantity control valve 11 from the flow channel 75 also stand out in whole or in part. In addition, it can alternatively be provided that the driver 47 is shaped so that its flow coefficients are different depending on the flow direction.

9 shows an embodiment of the quantity control valve 11 in which the hydraulic driver 47 and the valve needle 45 are made in one piece. The hydraulic driver 47 is through another covenant 47 the valve needle 45 educated.

The 10 and 11 each show the variants of the valve needles provided in the first and second embodiments 45 with hydraulic drive 47 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1701031 A1 [0002]
• DE 102004016554 A1 [0003]
• - DE 102004019152 [0003]
• - DE 10358858 [0003]
• - DE 102004032721 [0003]

Claims (11)

High pressure pump ( 9 ) for a fuel system ( 1 ) an internal combustion engine ( 19 ) with an inlet valve device ( 11 ), which by means of an actuator ( 55 . 57 ) can be forcibly brought into a certain position and / or held in a certain position, characterized in that the inlet valve device ( 11 ) a valve needle ( 45 ) and a valve body ( 39 ) and the valve needle ( 45 ) a hydraulic driver ( 47 ) obtained from the inlet valve device ( 11 ) in a delivery room ( 37 ) inflowing fuel to the valve needle ( 45 ) one in the opening direction ( 51 ) exerts force. High pressure pump ( 9 ) according to claim 1, characterized in that the driver ( 47 ) at from the pumping room ( 37 ) into the inlet valve device ( 11 ) flowing out a fuel against the opening direction ( 51 ) acting force on the valve needle ( 45 ), which is lower than that with inflowing fuel to the valve needle ( 45 ) in the opening direction ( 51 ) Acting force. High pressure pump ( 9 ) according to claim 2, characterized in that one of the driver ( 47 ) limited free cross-sectional area of a fuel-flow area ( 49 ) by moving the valve needle ( 45 ) in the opening direction ( 51 ) is enlargeable. High pressure pump ( 9 ) according to one of the preceding claims, characterized in that the driver ( 47 ) with the valve needle ( 45 ) is integrally connected. High pressure pump ( 9 ) according to one of the preceding claims, characterized in that the actuating device ( 55 . 57 ) is electromagnetically actuated. High pressure pump ( 9 ) according to one of the preceding claims, characterized in that it comprises a return spring ( 53 ), which in such a way on the valve needle ( 45 ) attacks that on the valve needle ( 45 ) a force against the opening direction ( 51 ) acts. High pressure pump ( 9 ) according to one of the preceding claims, characterized in that it comprises a first valve body ( 39 ) facing stop ( 85 ), which is connected to a first of the valve body ( 39 ) facing away counter stop ( 91 ) of the valve needle ( 45 ) cooperates, and / or a second of the valve body ( 39 ) facing away from the stop ( 87 ) connected to a second valve body ( 39 ) facing counter-attack ( 93 ) of the valve needle ( 45 ) cooperates. High pressure pump ( 9 ) according to claim 7, characterized in that the first stop ( 85 ) and the second stop ( 87 ) as a respective orthogonal to a longitudinal axis of the valve needle arranged abutment surface ( 85 ) of a first ( 81 ) and a second ( 83 ) Guide element are formed and the valve needle ( 45 ) one between the two guide elements ( 81 . 83 ) arranged stop section ( 89 ), on which the first ( 91 ) and the second counter-attack ( 93 ) as in each case orthogonal to the longitudinal axis of the valve needle ( 45 ) arranged counter stop surface are formed. Method for operating a high-pressure pump ( 9 ) for a fuel system ( 1 ) an internal combustion engine ( 19 ) with an inlet valve device ( 11 ), which forcibly by an energization of an actuator ( 55 . 57 ) is brought into a certain position and / or held in a certain position, characterized in that from the inlet valve device ( 11 ) in a delivery room ( 37 ) inflowing fuel to the valve needle ( 45 ) one in the opening direction ( 51 ) acting force is exercised and that the actuating device ( 55 . 57 ) is applied after a suit duration (t _A ) after the beginning of the energization during a holding period (t _H ) with a reduced average current. Method according to claim 9, characterized in that the energization of the actuating device ( 55 . 57 ) with the reduced average current intensity by applying the actuating device ( 55 . 57 ) is performed with a pulse width modulated signal and / or using a current control. A method according to claim 9 or 10, characterized in that the holding period (t _H ) using a setpoint (p _s ) and an actual value (p) of a pressure in a fuel rail ( 15 ) is determined.