DE102010027745A1 - high pressure pump - Google Patents

Abstract

A high-pressure pump (1), which is used in particular as a radial or in-line piston pump for fuel injection systems in air-compressing, self-igniting internal combustion engines, comprises a cylinder head (2) and a pump assembly (6). The cylinder head (2) has a cylinder bore (4) in which a pump piston (5) of the pump assembly (6) is guided. The pump piston (5) delimits a pump working space (12) in the cylinder bore (4). In addition, an inlet valve (20) integrated into the cylinder head (2) is provided, via which fuel can be fed into the pump work chamber (12). By controlling the inlet valve (20), a metering of the fuel led into the pump work space (12) is made possible. The pump work space (12) can be completely filled. However, partial filling of the pump work chamber (12) can also be achieved by suitable activation of the inlet valve (20).

Description

State of the art

The invention relates to a high-pressure pump, in particular a radial or linear piston pump. Specifically, the invention relates to the field of fuel pumps for fuel injection systems of air-compression, self-igniting internal combustion engines. The high pressure pump can also serve as a piston pump for conveying other suitable liquids.

From the DE 195 15 191 A1 is a high pressure fuel pump known. The high-pressure fuel pump has a cylinder whose upper part is exposed to the outside of the head cover, which is part of the engine housing. The remaining portion of the high-pressure fuel pump is accommodated in a housing hole of the head cover. A pump cam is mounted on a valve camshaft for driving an intake / exhaust valve and drives the high pressure fuel pump. Further, since the timing with which the pressurized fuel is discharged is controlled by the operation of a solenoid valve, the accuracy with which the fuel delivery is controlled is improved.

The from the DE 195 15 191 A1 known high-pressure fuel pump is a suction throttled pump in which there are several disadvantages. Disadvantages are high noise, poor controllability and the occurrence of mechanical vibrations due to cavitations occurring in the feed lines to the intake valves. Pressure waves between a metering unit and the suction valve have an unfavorable effect on the operation.

Disclosure of the invention

The high-pressure pump according to the invention with the features of claim 1 has the advantage that an improved embodiment realized in which in particular a metering of fuel and a compact design are possible. Specifically, a metering unit or the like can be saved, resulting in a significant cost reduction in the production.

The measures listed in the dependent claims advantageous refinements of the claim 1 high-pressure pump are possible.

In contrast to high-pressure pumps with a suction-side volume flow control by means of a Zumessmengeneinheit in combination with spring-loaded intake valves, which have the disadvantages that at high pump speed no DC funding is guaranteed and that pressure oscillations in the low pressure noise, can advantageously realized a cost reduction by omitting a Zumessmengeneinheit be made possible even at high pump speeds equal promotion and noise reduction by avoiding pressure oscillations and possible cavitation in the low pressure can be achieved.

In a conventional embodiment, the suction phases overlap especially in multi-punch pumps with three or more pistons. Pressure oscillations then lead to particularly large differences in the conveyed quantity. This can be avoided in an advantageous manner. It is possible that such differences in the upstream quantity are excluded.

Specifically, there is a great cost advantage in a high-pressure pump designed as a stamping pump. Also in the embodiment as a two-piston pump with a further actuator can be partially compensated by the saving of holes in the housing of the high-pressure pump additional costs. A major advantage of the direct control is the expansion of the pump speed and thus an improvement in the efficiency of the high-pressure pump.

In addition, a very small size can be realized by the integration of the intake valve in the cylinder head. This also applies to very high pressures, for example of 300 MPa (3000 bar), as is conceivable for applications in commercial vehicles.

Advantageously, the inlet valve is designed as a magnetically controllable inlet valve. Furthermore, it is advantageous that the inlet valve is fixed to the cylinder head by means of a screw plug screwed into the cylinder head, and that the closure screw is formed from a ferromagnetic material. As a result, the screw plug can serve as a magnetic conductor, which increases the efficiency of the magnetic circuit and allows a high magnetic force.

In addition, it is advantageous that a magnetic coil is provided that by energizing the solenoid coil, a control of the intake valve is made possible and that the solenoid coil can be cooled by the over the inlet valve in the pump working space feasible fuel. Thus, the cooling of the magnetic coil and the other elements of the magnetic circuit can be achieved by flushing with the fuel.

It is also advantageous that the inlet valve has a valve body and one with the Valve body to a sealing seat cooperating valve tappet, wherein the valve stem rests against the cylinder head, wherein a magnetically actuated plunger armature is provided and wherein the plunger armature for opening the seal formed between the valve body and the valve stem during magnetic actuation entrains the valve lifter. As a result, the magnetic force for actuating the inlet valve can be generated via the plunger armature, wherein the closure screw advantageously serves as a magnetic conductor. The inlet valve is preferably closed when the solenoid is switched off. If the magnet coil of the magnet is energized and the pump piston is at top dead center, for example, then the inlet valve opens. When fully filled, the inlet valve is preferably open until bottom dead center of the pump piston. Here, it is also advantageous that a shim is provided, which serves to specify a working air gap and a residual air gap for the plunger armature. As a result, a modular design is possible, with an adaptation to the particular application of the high pressure pump is possible by installing a suitable shim. As a result, the scope of the high pressure pump is increased, with a simple adjustment and a largely identical design of the high-pressure pump is possible.

It is also advantageous that a controller is provided which controls the inlet valve in response to a movement of the pump piston of the pump assembly. On the one hand, it is advantageous that the controller for reducing a filling of the pump chamber of the pump assembly shortens the drive time at its end so that the inlet valve is closed before reaching a bottom dead center of the pump piston or the drive time at its end extended so that the inlet valve after reaching a bottom dead center of the pump piston is closed. Thus, the driving time can be reduced so that the inlet valve is closed again before reaching the bottom dead center of the pump piston, which reduces the amount of fuel flowing into the pump working space. On the other hand, this can also be achieved in that the injection valve is closed only after reaching the bottom dead center, whereby the guided into the pump working chamber fuel is partially conveyed back via the inlet valve in the opposite direction via the movement of the pump piston. In the first case, the pressure oscillations on the low pressure side. reduced. In the second case, preferably no cavities arise in the working cylinder. Depending on the application, the advantageous variant can be specially selected. Another possibility is that the activation time is shortened at its beginning so that the inlet valve is opened only after reaching a top dead center of the pump piston. Thus, the intake valve is not opened immediately after top dead center, so that the amount of fuel flowing into the pump working space is also reduced. In this case, a suitable combination of the drive types can be carried out by the controller. For example, the driving time can be shortened both at the beginning and at the end. Thus, partial fillings of the pump working space can be realized in an advantageous manner. Furthermore, pressure fluctuations with respect to the amplitude and frequency can be positively influenced by one or more throttles arranged upstream of the inlet valve. In addition, the volume control can be positively influenced. As a result, the noise behavior, which can be adversely affected by pressure oscillations in the low pressure, can be improved.

The inlet valve is preferably equipped with a closing spring which has a high spring bias in order to achieve a high closing dynamics.

Short description of the drawing

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings. It shows:

1 a high-pressure pump in a partial, schematic, axial sectional view according to an embodiment of the invention.

Embodiments of the invention

1 shows a high pressure pump 1 in an excerpt, schematic, axial sectional view according to an embodiment of the invention. The high pressure pump 1 can be configured in particular as a radial or inline piston pump. Specifically, the high pressure pump is suitable 1 as a fuel pump for fuel injection systems of air-compressing, self-igniting internal combustion engines.

A preferred use of the high-pressure pump 1 consists of a fuel injection system with a fuel rail that stores diesel fuel under high pressure. The high-pressure pump according to the invention 1 However, it is also suitable for other applications. In particular, the high-pressure pump can also be configured as a piston pump for conveying suitable liquids, that is to say also other liquids as fuel.

The high pressure pump 1 has a pump housing to which a cylinder head 2 is mounted. Of the cylinder head 2 has an approach 3 on, which projects into a bore of the pump housing. Here is in the approach 3 a cylinder bore 4 designed in which a pump piston 5 a pump assembly 6 along an axis 7 is guided.

The high pressure pump 1 also has a drive shaft 8th on, on which a cam 9 is provided. The cam 9 can also be used as a multiple cam or as an eccentric step of the drive shaft 8th be designed. During operation, the drive shaft rotates 8th with the cam 9 around a rotation axis 10 , Between the pump piston 5 the pump assembly 6 and the cam 9 there is an active connection 11 by the double arrow 11 is illustrated. For example, via a roller shoe and a roller mounted in the roller shoe, an actuating force from the cam 9 on the pump piston 5 be transmitted. A return of the pump piston 5 can be done via a suitable plunger spring.

Thus, the pump assembly 6 from the cam 9 the drive shaft 8th drivable. Depending on the design of the high-pressure pump 1 can also other pump assemblies of the cam 9 are driven. Also, on the drive shaft 8th Also further cams may be provided which serve to drive other pump assemblies. Depending on the configuration, this can be a designed as a radial or piston pump series high-pressure pump 1 will be realized.

The pump piston 5 limited in the cylinder bore 4 a pump workroom 12 , For supplying fuel serves an inlet channel 13 in which fuel is conveyed by a prefeed pump. In the inlet channel 13 are a first throttle 14 and a second throttle 15 intended. The inlet channel 13 leads into a low-pressure room 16 passing through a recess 17 in the cylinder head 2 is formed.

The high pressure pump 1 has an inlet valve 20 on. The low pressure room 16 is part of the inlet valve 20 , The inlet valve 20 is in the cylinder head 2 integrated. Here is the inlet valve 20 in the recess 17 of the cylinder head 2 arranged. The recess 17 is here by a screw plug 21 locked. Thus, also the low pressure space 16 completed towards the environment. The screw plug 21 acts via a valve part 22 on a valve body 23 one. The screw plug 21 is in the cylinder head 2 screwed in and thereby presses the valve body 23 against one on the cylinder head 2 trained contact surface 24 , The screw plug 21 , the valve part 22 and the valve body 23 of the inlet valve 20 are thereby fixed in place. In addition, the screw plug 21 and the valve part 22 preferably formed from a ferromagnetic material.

In the valve body 23 is a valve lifter 25 guided. The valve tappet acts here 25 with one on the valve body 23 formed valve seat surface 26 to a sealing seat together. A valve spring 27 acts on the valve tappet 25 in this case against the valve seat surface 26 , The valve spring 27 acts via a valve element 28 and a dial 29 on an anchor 30 one. The anchor 30 is as a plunger anchor 30 designed. The plunger anchor 30 is with the valve lifter 25 connected. Thus, the valve tappet 25 from the bias of the valve spring 27 applied. The valve lifter 25 , the valve element 28 , the dial 29 and the plunger anchor 30 of the inlet valve 20 are movable elements that control the intake valve 20 for opening the inlet valve 20 to be moved.

The inlet valve 20 also has a magnet 31 with a magnetic coil 32 on. The magnetic coil 32 is via electrically conductive pins 33 . 34 with pins 35 . 36 a plug 37 electrically connected. The plug 37 allows the connection to a control unit 38 , The control unit 38 serves as a controller in this embodiment 38 , The control 38 can also be integrated in a central control unit. The control unit 38 is with a rotation angle sensor 39 connected, the current rotational angle of the drive shaft 8th recorded and sent to the control unit 38 outputs. About the detected rotation angle is a direct relationship with the current position of the pump piston 5 , Specifically, it can thus be detected whether the pump piston 5 located at a top dead center, where the pump piston experiences a maximum stroke and the pump working space 12 having a minimal volume. Accordingly, it can be detected whether the pump piston 5 located at a bottom dead center, at which the pump piston 5 having a minimum stroke and the volume of the pump working space 12 is maximum.

By energizing the solenoid 32 a magnetic field is generated. This magnetic field comes from the magnet 31 out, wherein over the ferromagnetic locking screw 21 a gain is possible. The magnetic circuit also passes over the valve member 22 , the plunger anchor 30 and optionally via further ferromagnetic elements back to the screw plug 21 , Here is between the plunger anchor 30 and the valve part 22 A gap 40 intended. The gap 40 on the one hand enables the displaceability of the plunger anchor 30 and thus an adjustment of the valve stem 25 for actuating the inlet valve 20 , On the other hand remains as a gap 40 at least one residual air gap, in the actuated state, a so-called magnetic adhesive effect of the plunger anchor 30 on the valve part 22 to avoid. In particular, it can be during the currentless switching of the magnetic coil 32 the force of the valve spring 27 largely without delay closing the inlet valve 20 initiate. The maximum size of the gap 40 is given by the sum of a desired working air gap and the residual air gap. An adjustment of the residual air gap and the working air gap is by a suitable choice of the valve element 28 and the dial 29 allows. Specifically, through the thickness of the shim 29 the desired working air gap can be specified. The thickness of the shim 29 thus gives the stroke of the valve lifter 25 in front. With unchanged geometry in the area of the valve seat surface 26 can thereby the opening cross-section of the valve seat surface 26 changed and thus also the possible flow in the pump working space 12 be adjusted with the seal seat open. As a result, in relation to the respective application, an adaptation of the inlet valve 20 possible.

By actuating the inlet valve 20 can thus fuel from the low-pressure space 16 into the pump workroom 12 be guided. The operation of the inlet valve 20 takes place during a suction stroke of the pump piston 5 , During the delivery stroke of the pump piston 5 is the inlet valve 20 preferably closed. This will cause high pressure fuel through an exhaust valve 41 as a directional or check valve 41 can be configured in a high-pressure line 42 promoted. The high pressure line 42 For example, it is connected to a fuel rail.

When the inlet valve 20 at about top dead center of the pump piston 5 opened and at the bottom dead center of the pump piston 5 is closed, then a full filling of the pump work space 12 be achieved. However, the inlet valve can 20 from the controller 38 regardless of the stroke or the current position of the pump piston 5 be controlled during the suction phase. This can also be a partial filling of the pump working space 12 will be realized. There are several options for this, which can also be combined if necessary.

One possibility is that the activation time of the intake valve 20 is reduced so that the inlet valve 20 before reaching the bottom dead center of the pump piston 5 is closed again. Alternatively, the drive time may be extended beyond reaching bottom dead center. The inlet valve 20 will then only after reaching the bottom dead center of the pump piston 5 closed, leaving a portion of the fuel from the pump workspace 12 during the stroke of the pump piston 5 in the opposite direction through the inlet valve 20 is promoted back. The other part of the fuel is then via the high pressure line 42 promoted. The total over the high pressure line 42 Promoted amount of fuel per pump stroke is thereby reduced.

It should be noted that in this case there is no control of the fuel to a tank or the like. In addition, in this way, if appropriate, a noise behavior can be improved by damping pressure pulsations. A vote here is about the chokes 14 . 15 possible.

Another way to achieve a partial filling is that the inlet valve does not immediately after reaching the top dead center of the pump piston 5 is opened. As a result, a certain idle stroke of the pump piston 5 scored, so that the total in the pump work space 12 Fuel flowing in via the opening cross-section of the opened sealing seat is reduced.

This can advantageously by one or more upstream of the inlet valve throttles 14 . 15 or damping volumes, the pressure fluctuations in terms of amplitude and frequency and the amount of control can be reduced. The chokes allow this a large partial reflection and a low attenuation of pressure and dilution waves. Damping volumes allow a lower partial reflection and a stronger damping of the pressure and dilution waves. This depends on the geometric design of the respective damping volume. By opening and closing the inlet valve 20 or optionally more according to the inlet valve 20 designed inlet valves arise pressure and dilution waves, which run from the inlet valves to a feed pump, in particular an electric fuel pump and reflected there. The reflected waves can inter alia during an opening operation of the intake valve 20 arrive again and thus additionally influence the filled mass in the pump working space, which can lead to delivery fluctuations of the high-pressure pump. With the help of damping volumes and throttles 14 . 15 in the inlet channel 13 and their vote, these pressure waves can be reduced so far that a uniform promotion of the high-pressure pump 1 within a certain tolerance range. The design and dimensioning depends on the field of application of the high-pressure pump 1 and the connection to the pre-feed pump.

Advantageously, thus an inlet valve 20 be realized, which is closed in the de-energized state. This inlet valve 20 is in the cylinder head 2 integrated. In this case, the principle Tauchanker be exploited, so that a quick opening and closing of the inlet valve 20 can be achieved. Furthermore, the suction throttling can be moved into the working cylinder, in which an air outgassing is deliberately used. The required dynamics can be ensured by one or more connection holes. About a correspondingly high spring preload of the valve spring 27 a sufficiently high closing dynamics can be achieved. The cooling of the magnet 31 with the magnetic coil 32 can be achieved by flushing the fuel.

The invention is not limited to the described embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19515191 A1 [0002, 0003]

Claims (10)

High pressure pump ( 1 ), in particular radial or inline piston pump for fuel injection systems of air-compressing, self-igniting internal combustion engines, with at least one cylinder head ( 2 ) and a pump assembly ( 6 ), wherein the cylinder head ( 2 ) a cylinder bore ( 4 ), in which a pump piston ( 5 ) of the pump assembly ( 6 ) is guided, wherein the pump piston ( 5 ) in the cylinder bore ( 4 ) a pump work space ( 12 ), wherein one in the cylinder head ( 2 ) integrated inlet valve ( 20 ) is provided via the fuel into the pump work space ( 12 ) is feasible, and wherein by driving the inlet valve ( 20 ) a metering of the into the pump work space ( 12 ) guided fuel is possible. High-pressure pump according to claim 1, characterized in that the inlet valve ( 20 ) as magnetically controllable inlet valve ( 20 ) is trained. High-pressure pump according to claim 1 or 2, characterized in that the inlet valve ( 20 ) by means of a in the cylinder head ( 2 ) screwed in screw plug ( 21 ) on the cylinder head ( 2 ) is fixed and that the screw plug ( 21 ) is formed of a ferromagnetic material. High-pressure pump according to one of claims 1 to 3, characterized in that a magnetic coil ( 32 ) is provided that by energizing the magnetic coil ( 32 ) a control of the inlet valve ( 20 ) and that the magnetic coil ( 32 ) through the inlet valve ( 20 ) into the pump work space ( 12 ) feasible fuel is coolable. High-pressure pump according to one of claims 1 to 4, characterized in that the inlet valve ( 20 ) a valve body ( 23 ) and one with the valve body ( 23 ) to a sealing seat cooperating valve tappets ( 25 ), wherein the valve tappet ( 25 ) on the cylinder head ( 2 ) is applied, wherein a magnetically actuable solenoid plunger ( 30 ) is provided and wherein the plunger ( 30 ) for opening the between the valve body ( 23 ) and the valve tappet ( 25 ) formed in the magnetic actuation the valve stem ( 25 ) takes along. High-pressure pump according to claim 5, characterized in that a shim ( 29 ) provided for setting a working air gap for the plunger anchor ( 30 ) serves. High-pressure pump according to one of claims 1 to 6, characterized in that a control ( 38 ) is provided, which the inlet valve ( 20 ) in response to a movement of the pump piston ( 5 ) of the pump assembly ( 6 ). High-pressure pump according to claim 7, characterized in that the controller ( 38 ) for reducing a filling of the pump working space ( 12 ) of the pump assembly ( 6 a) the actuation time at its end is shortened so that the inlet valve ( 20 ) before reaching a bottom dead center of the pump piston ( 5 ) is closed, or the activation time at its end extended so that the inlet valve ( 20 ) after reaching a bottom dead center of the pump piston ( 5 ) is closed, and / or b) the activation time at its beginning so shortened that the inlet valve ( 20 ) after reaching a top dead center of the pump piston ( 5 ) is open. High-pressure pump according to one of claims 1 to 8, characterized in that the inlet valve ( 20 ) a low-pressure space ( 16 ), which in a recess ( 17 ) of the cylinder head ( 2 ), in which the inlet valve ( 20 ) is formed, and by a screw plug ( 21 ) of the inlet valve ( 20 ) is closed, and / or that an inlet channel ( 13 ), which enters the low-pressure space ( 16 ), is provided, and that in the inlet channel ( 13 ) at least one throttle ( 14 . 15 ) and / or at least one damping volume is arranged. High-pressure pump according to one of claims 1 to 9, characterized in that the inlet valve ( 20 ) a closing spring ( 27 ) and that a high spring bias of the closing spring ( 27 ) is given.

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