DE102013212145A1 - pump - Google Patents

Abstract

A high-pressure pump (1), which is used in particular for fuel injection systems of internal combustion engines, comprises a low-pressure chamber (4) designed as an engine compartment (4) and a drive (5) which is arranged at least partially in the low-pressure chamber (4). By the drive (5) pressure pulsations in the low-pressure space (4) are generated during operation. Here, a damping device (30) is provided which is connected on the one hand to the low pressure chamber (4) and on the other hand connected to a low pressure level (25), which is in operation in the low pressure space (4) under a pressure (p1). The damping device (30) has a piston (32) displaceable in a piston bore (33), which on the one hand is acted on by the pressure (p1) in the low-pressure space (4) against a spring force of a spring element (36) and, on the other hand, a vapor space (34 ) in the piston bore (33) limited. Furthermore, the damping device (30) on a discharge device (37), which connects the vapor space (34) at least temporarily with the low pressure level (25).

Description

State of the art

The invention relates to a pump, in particular a high-pressure pump for fuel injection systems or hydraulic applications. Specifically, the invention relates to the field of diesel pumps, gasoline pumps and hydraulic pumps.

From the DE 10 2009 003 054 A1 is a high-pressure pump for fuel injection systems of air-compressing, self-igniting internal combustion engines known. The known high-pressure pump has a pump assembly and a drive shaft, wherein the drive shaft comprises a cam associated with the pump assembly. The pump assembly includes a roller that rolls on a tread of the cam. The drive shaft is mounted at bearings in housing parts of the high-pressure pump. During operation of the high-pressure pump, a reciprocating movement of a piston is achieved, so that the delivery of high-pressure fuel to a common rail takes place. During operation of the high-pressure pump, the drive shaft rotates about an axis.

The from the DE 10 2009 003 054 A1 known high-pressure pump has the disadvantage that in operation by the volume displacement of the piston in the engine room, in which the drive shaft is provided by the delivery characteristic or additionally by engine part movements volume waves are generated, which are emitted to the further low-pressure system or another low pressure area and increased there Lead to pressure loads. This applies in particular to high-pressure pumps with only one pump assembly or with only one high-pressure cylinder with pump piston guided therein. As a result, there may be noises or a reduction in the service life of the high-pressure pump.

Disclosure of the invention

The pump according to the invention with the features of claim 1 has the advantage that an improved structure and improved operation are possible. Specifically, during operation, pressure pulsations generated in the low pressure space can be effectively damped to reduce adverse effects.

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

The pump can in particular be configured as a high-pressure pump, which serves for conveying a fluid, in particular fuel, with high pressure. For example, the high pressure pump may be integrated with a fuel injection system or other hydraulic system. Here, a low-pressure circuit can be formed, which runs over the low-pressure chamber of the pump. The low-pressure space can in this case be designed as an engine room of the pump, the drive being arranged at least partially in the low-pressure space designed as an engine compartment. Thus, lubrication of the drive can be achieved via the low-pressure circuit at the same time. Pressure pulsations, which are generated by the drive in the engine room designed as the low-pressure space of the pump, are then preferably already damped within the housing of the pump by the at least one damping device. This reduces the effects of such pressure pulsations on other parts of the low pressure circuit. Other damping devices that may be provided in the low-pressure circuit can thereby be simplified in their design and optionally also omitted. Thus, the design of the low pressure circuit and thus the fuel injection system or the like is simplified.

The fluid, in particular the fuel, can be guided in an advantageous manner via the low-pressure space at least indirectly to a pump working space of a pump assembly. The low-pressure space may in particular be the engine room. Also possible here are embodiments in which the pump has a plurality of pump assemblies and correspondingly a plurality of pump working chambers, to which the fluid, in particular the fuel, is led via the low-pressure chamber.

It is advantageous that the relief device has a throttle which connects the vapor space at least indirectly with the low pressure level, and / or a check valve opening to the low pressure level, which is at least indirectly connected at least indirectly to the vapor space and at least indirectly to the low pressure level. The damping of the pressure pulsations can thus be realized by the piston, which is mounted against the spring force.

In one possible embodiment, the vapor space is connected via the throttle to the lower low pressure level. The throttle is in this case advantageously adjusted depending on a pulsation frequency and a Pulsationsamplitude and the low pressure level after the throttle so that when expanding the steam chamber as large a vapor volume is generated, the re-immersion of the piston until the complete condensation of the vapor as Damping volume is available without a renewed volume displacement takes place.

In a second possible embodiment of the vapor space is connected via the check valve to an at least calmed and / or lower low pressure level in an advantageous manner. Advantageously, a piston leakage can be removed via the check valve and a vapor volume can be forced, which is available as a damping volume.

These possibilities of damping are cost-effective and maintenance-free, since the functionality can be ensured by the absence of permanent sealing points between on the one hand the gas and / or vapor phase and on the other hand the liquid over the entire life.

Further, there is a significant advantage over a gas spring or the like in that an operating point, in particular the required mean pressure by which the pressure amplitudes fluctuate, via a spring element that applies the spring force, can be adjusted. On the other hand, in the case of a gas pressure damper, this must be ensured either by precompressing the gas or by high elasticity, since it is possible only to a limited extent without losing a large part of the damping effect. The operating point is thus easier to apply.

It is advantageous that the throttle of the relief device opens radially into the piston bore. The piston bore can be closed by a suitable closure element. In this embodiment, a low low pressure level can be kept in a particularly simple manner, with which the vapor space is connected via the throttle.

In a modified embodiment, it is advantageous that in the piston bore a closure element is arranged, that the vapor space between the piston and the closure element is formed in the piston bore and that the throttle of the relief device is integrated into the closure element. In this way, the access required for the piston bore can be used at the same time to maintain the low pressure level.

In a further possible embodiment, it is advantageous that the piston bore is arranged in a housing, that a low-pressure channel is formed in the housing, which opens into the vapor space of the piston bore, and that the check valve is arranged in the low-pressure passage. As a result, integration of the check valve in the housing of the pump is possible. Thus, a compact design can be realized.

However, it is also advantageous that in the piston bore a closure element is arranged, that the vapor space between the piston and the closure element is formed in the piston bore and that the check valve is integrated into the closure element. Thus, the essential functions can be realized in the field of piston bore. The space required within the housing, which is needed for this realization, this is minimized.

Advantageously, a spring element is arranged in the vapor space, which acts on the piston with the spring force. The steam space can thus serve as a spring chamber at the same time. The spring element can be pressurized by the piston in this case. However, the piston may also be suitably connected to the spring element to urge the piston both on pressure and on train.

Furthermore, it is advantageous that the piston is guided in the piston bore such that a leakage flow from the low-pressure space into the vapor space is made possible between the piston and the piston bore. As a result, on the one hand a lubrication of the piston guide is realized in the piston bore. At the same time thereby a Nachfluss of fluid, in particular fuel, is realized in the vapor space. As a result, the required volume of steam can always be generated and at the same time an advantageous damping behavior can be achieved. The leakage is then removed via the throttle or the check valve to the low pressure level. Thus, a maintenance-free operation is possible.

Brief description of the drawings

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. Show it:

1 a high pressure pump of a fuel injection system in a schematic representation according to a first embodiment of the invention;

2 an excerpts, schematic sectional view of in 1 illustrated high-pressure pump according to a second embodiment of the invention;

3 an excerpts, schematic sectional view of in 1 shown High pressure pump according to a third embodiment of the invention;

4 an excerpts, schematic sectional view of in 1 illustrated high pressure pump according to a fourth embodiment of the invention;

5 an excerpts, schematic sectional view of in 1 illustrated high pressure pump according to a fifth embodiment and

6 a diagram for explaining the operation of a high-pressure pump according to a possible embodiment of the invention.

Embodiments of the invention

1 shows a high pressure pump 1 a fuel injection system 2 with a low pressure circuit 3 in a schematic representation according to a first embodiment. The high pressure pump 1 can be used in particular for air-compressing, self-igniting internal combustion engines or mixture-compressing, spark-ignited internal combustion engines. Furthermore, the high pressure pump 1 be designed as a hydraulic pump for other hydraulic applications.

The high pressure pump 1 has a low pressure space 4 and a drive 5 on. During operation, this is done by the drive 5 Pressure pulsations in the low pressure space 4 generated. In this embodiment, the low pressure space 4 formed by an engine room, in which an axis 6 with a multiple cam 7 at least partially arranged. The multiple cam 7 the axis 6 serves to drive a pump piston 8th a pump assembly 9 the high pressure pump 1 , Here is a schematic part of a cylinder head 10 shown in which a cylinder bore 11 is designed. The pump piston 8th is in the cylinder bore 11 guided. The actuation of the pump piston 8th through the multiple cam 7 is by a double arrow 12 illustrated.

Furthermore, a metering unit 13 provided, via the low-pressure operating fuel in a pump working space 14 to be led. The pump workroom 14 is in this case of the pump piston 8th in the cylinder bore 11 limited. Via an outlet valve 15 For example, in operation, the fuel under high pressure is led to a common rail.

By the drive 5 , in particular the reciprocating motion of the pump piston 8th , be in the low pressure room 4 Pressure pulsations generated. It should be noted that to simplify the illustration, the engine room (low pressure room) 4 separately from the drive 5 , in particular the axis 6 , which is at least partially in the engine room 4 is arranged.

The low pressure circuit 3 includes a tank 20 and a prefeed pump 21 , for example, as an electric fuel pump 21 can be designed. Through the pre-feed pump 21 the fuel gets out of the tank 20 via a filter device 22 in the low pressure room 4 promoted. The filter device 22 includes a filter and optionally also a water separator.

From the low pressure room 4 becomes part of the fuel via a housing bearing 23 and a flange bearing 24 to a low pressure level 25 guided. At the housing bearing 23 and the flange camp 24 is the axis 6 with the multiple cam 7 stored. The housing bearing 23 and the flange camp 24 are here by throttling 23 . 24 illustrates that they act as chokes.

In the low pressure room 4 For example, there is a pressure p ₁ . The low pressure level 25 has a pressure p ₂ which is smaller than the pressure p ₁ . At a certain, low pressure p ₂ at the low pressure level 25 may hold a facility if necessary 26 be provided. As a result, the pressure p _2, for example, something about the optionally pressure-relieved tank 20 being held. The device 26 may for example have a throttle or other low pressure limit. Depending on the design of the low-pressure circuit 3 can the decor 26 also omitted. Specifically, already by the length of a return line 27 that of the low pressure level 25 to the tank 20 leads, the desired low pressure p ₂ in the low pressure level 25 be achieved.

The high pressure pump 1 has a damping device 30 on. Depending on the design of the high-pressure pump 1 can also have several such damping devices 30 be provided. The damping device 30 is on the one hand by means of a line 31 with the low-pressure room 4 connected and on the other hand to the low pressure level 25 connected. In operation, the low pressure level 25 with its pressure p ₂ under the pressure p ₁ in the low-pressure space 4 , Thus, there is the damping device 30 a pressure gradient from the low pressure space 4 to the low pressure level 25 ,

When pressure pulsations occur, pressure oscillations occur in the low-pressure space 4 what a damping by the damping device 30 triggers. For this purpose, the damping device 30 in this embodiment, a piston 32 on, as a balance piston 32 serves. The piston 32 is in a piston bore 33 slidably guided. In this embodiment, the piston divides 32 the piston bore 33 in a steam room 34 and a room 35 , The steam room 34 at the same time serves as a spring chamber 34 in which a spring element 36 is arranged, for example, as a spiral spring 36 is designed.

From the room 35 Her is the piston 32 from the pressure p ₁ in the low pressure space 4 against the spring force of the spring element 36 applied. On the other hand, the piston limits 32 the steam room 34 in the piston bore 33 ,

The damping device 30 also has a discharge device 37 on top of the steam room 34 with the low pressure level 25 combines. In this embodiment, the discharge device comprises 37 a check valve 38 , The check valve 38 opens to the low pressure level 25 out.

The fuel flow in the low-pressure circuit 3 is illustrated by arrows. Here is between the low pressure space 4 and the room 35 the damping device 30 a fuel exchange and thus a fluid flow in both directions 39 . 40 possible. This fluid exchange occurs when pressure pulsations occur.

If it due to the pressure pulsations to a lowering of the pressure p ₁ in the low pressure space 4 comes, then fuel flows out of the room 35 in the low pressure room 4 , This will cause the piston 32 due to the spring force of the spring element 36 adjusted so that the volume of the steam room 34 increases. Because the check valve 38 an inflow of fuel into the steam room 34 Lock, arises according to adjustment of the piston 32 in the steam room 34 a certain volume of steam. The pressure pulsation then generates a pressure rise of the pressure p ₁ in the low-pressure space according to its time course 4 , This results in a provision of the piston 32 against the spring force of the spring element 36 , The previously formed vapor volume thus disappears according to the return movement of the piston 32 ,

The piston 32 is so in the piston bore 32 led that between the piston 32 and the piston bore 33 a leakage flow from the with the low pressure space 4 connected room 35 in the steam room 34 is possible. The leakage is in this case in operation via the check valve 38 to the low pressure level 25 dissipated.

2 shows a partial, schematic sectional view of the in 1 illustrated high-pressure pump 1 according to a second embodiment. Here is a housing part 45 represented, the part of a housing 46 the high pressure pump 1 is where the low pressure space 4 is designed. In the case part 45 it can also be the cylinder head 10 act.

In this embodiment is in the housing part 45 a tubular sleeve 47 used in the piston bore 33 is designed. This is in the sleeve 47 a closure element 48 used that the piston bore 33 to an outside 49 of the housing part 45 closes. The steam room 34 is between the piston 32 and the closure element 48 in the piston bore 33 educated.

Furthermore, in the housing part 45 a channel 50 formed, which is to the sleeve 47 extends. The low pressure level 25 with the pressure p ₂ is in this case in the channel 50 realized.

In this embodiment, the discharge device 37 a throttle 51 on, the radially into the piston bore 33 empties. The throttle 51 is in this embodiment in the sleeve 47 designed. Here, the throttle connects 51 the steam room 34 with the channel 50 ,

The throttle effect of the throttle 51 is so strong that at a pressure reduction in the low pressure space 4 , which is caused by a pressure pulsation and an adjustment of the piston 32 with the spring force of the spring element 36 allows, until a return of the piston 32 caused by the following pressure increase in the low-pressure space caused by the pressure pulsation 4 takes place, at times a vapor volume in the vapor space 34 is produced.

The damping device 30 can in particular by the spring element 36 and the throttle 51 be matched. Here, the throttle effect of the throttle 51 as a function of a pulsation frequency and a pulsation amplitude as well as the low pressure level 25 with the pressure p ₂ after the throttle 51 be tuned so that when expanding the spring element 36 the largest possible volume of steam in the steam room 34 is generated, the re-immersion of the piston 32 is available until the complete condensation of the steam as a damping volume, without a renewed volume displacement takes place.

3 shows a partial, schematic sectional view of the in 1 illustrated high-pressure pump 1 according to a third embodiment. In this embodiment, the closure element 48 a through hole 52 on. The through hole 52 may be formed at least in sections with a sufficiently small diameter to the throttle 51 to build. That way, the throttle can 51 in the closure element 48 to get integrated. At one page 53 the closure element 48 coming from the steam room 34 is turned away, a return to the return line is suitably 27 designed. Thus, on the side 53 the closure element 48 the low pressure level 25 be ensured with the pressure p ₂ .

4 shows a partial, schematic sectional view of the in 1 illustrated high-pressure pump 1 according to a fourth embodiment. In this embodiment, the damping device 30 a part 54 on, as a screw or plug-in part 54 is configured and in the housing part 45 screwed or inserted. The part 54 has a tubular section 55 on, in which the piston bore 33 is trained. The tubular section 55 of the part 54 is opposite the housing part 55 with a sealing ring 56 sealed.

In the piston bore 33 of the tubular portion 55 is the closure element 48 arranged. Furthermore, another closure element 57 provided that the piston bore 33 closes to the environment. Between the further closure element 57 and the closure element 48 is the low pressure level 25 in a gap 58 specified. The gap 58 is suitably connected to the return line 27 connected.

In this embodiment, the check valve 38 in the closure element 48 integrated. This allows the check valve 38 a fuel flow from the steam room 34 in the gap 58 , Due to this fuel flow, the leakage due to the leakage flow between the piston 32 and the piston bore 33 in the steam room 34 reaches, to the return line 37 be guided.

5 shows a partial, schematic sectional view of the in 1 illustrated high-pressure pump 1 according to a fifth embodiment. In this embodiment, the piston bore 33 of the part 54 through the closure element 48 closed to the environment. Further, the tubular portion 55 at least one radial connection bore 59 . 60 on, in this embodiment, a plurality of radial connection holes 59 . 60 are provided.

Furthermore, in this embodiment, in the housing part 45 the channel 50 designed. The channel 50 For example, by a housing bore 50 in the housing part 45 be designed. In the channel 50 is the check valve 38 arranged. Thus, the steam room 34 over the radial connection holes 59 . 60 and the check valve 38 to the low pressure level 25 connected.

6 shows a diagram for explaining the operation of the high-pressure pump 1 according to a possible embodiment of the invention. In this case, the time t is plotted on the abscissa, while the pressure p is plotted on the ordinate. The pressure p results here from the pressure p ₁ in the low pressure space 4 plus the pressure fluctuations caused by pressure pulsations. The pressure pulsations are in this case by the drive 5 caused. One possible pressure pulsation is through the curve 61 illustrated. Thus, there is a pressure fluctuation around the considered as the mean pressure pressure p ₁ in the low pressure space 4 , The through the bend 61 However, pressure fluctuations are represented by the damping device 30 effectively damped. As a result, such pressure fluctuations do not affect the rest of the low-pressure circuit 3 out. In particular, the functionality of the metering unit 13 guaranteed.

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 102009003054 A1 [0002, 0003]

Claims (10)

Pump ( 1 ), in particular high-pressure pump ( 1 ) for fuel injection systems, with a low-pressure chamber ( 4 ) and a drive ( 5 ), during which pressure pulsations in the low-pressure space ( 4 ), characterized in that at least one damping device ( 30 ) is provided, on the one hand at least indirectly with the low-pressure space ( 4 ) and on the other hand to a low pressure level ( 25 ), which in operation under a pressure (p ₁ ) in the low pressure space ( 4 ) is that the damping device ( 30 ) one in a piston bore ( 33 ) displaceable piston ( 32 ), on the one hand by the pressure (p ₁ ) in the low pressure space ( 4 ) is acted upon by a spring force and on the other hand a vapor space ( 34 ) in the piston bore ( 33 ) and a discharge facility ( 37 ) having the vapor space ( 34 ) at least partially with the low pressure level ( 25 ) connects. Pump according to claim 1, characterized in that the relief device ( 37 ) a throttle ( 51 ), the steam room ( 34 ) at least indirectly with the low pressure level ( 25 ), and / or to the low pressure level ( 25 ) opening check valve ( 38 ), on the one hand at least indirectly with the vapor space ( 34 ) and on the other hand at least indirectly with the low pressure level ( 25 ) is connected. Pump according to claim 2, characterized in that the throttle ( 51 ) of the discharge device ( 37 ) radially into the piston bore ( 33 ) opens. Pump according to claim 2, characterized in that in the piston bore ( 33 ) a closure element ( 48 ) is arranged, that the steam space ( 34 ) between the piston ( 32 ) and the closure element ( 48 ) in the piston bore ( 33 ) is formed and that the throttle ( 51 ) of the discharge device ( 37 ) in the closure element ( 48 ) is integrated. Pump according to one of claims 2 to 4, characterized in that a throttle effect of the throttle ( 51 ) is so strongly specified that at a pressure reduction in the low-pressure space ( 4 ), which is caused by a pressure pulsation and an adjustment of the piston ( 32 ) with the spring force, until a return of the piston ( 32 ) caused by the pressure increase caused by the following pressure increase in the low pressure space ( 4 ), at times a volume of vapor in the vapor space ( 34 ) is producible. Pump according to one of claims 2 to 5, characterized in that the piston bore ( 33 ) in a housing ( 46 ) is arranged that a channel ( 50 ) in the housing ( 46 ) formed in the vapor space ( 34 ) of the piston bore ( 33 ) and that the check valve ( 38 ) in the channel ( 50 ) is arranged. Pump according to one of claims 2 to 5, characterized in that in the piston bore ( 33 ) a closure element ( 48 ) is arranged, that the steam space ( 34 ) between the piston ( 32 ) and the closure element ( 48 ) in the piston bore ( 33 ) is formed and that the check valve ( 38 ) in the closure element ( 48 ) is integrated. Pump according to one of claims 1 to 7, characterized in that in the vapor space ( 34 ) a spring element ( 36 ) is arranged, which the piston ( 32 ) acted upon by the spring force. Pump according to one of claims 1 to 8, characterized in that the low pressure space ( 4 ) as an engine room ( 4 ) and that the drive ( 5 ) at least partially in the engine room ( 4 ) formed low-pressure space ( 4 ) is arranged and / or that a fluid over the low pressure space ( 4 ) at least indirectly to a pump work space ( 14 ) is feasible. Pump according to one of claims 1 to 9, characterized in that the piston ( 32 ) so in the piston bore ( 33 ) is that between the piston ( 32 ) and the piston bore ( 33 ) a leakage flow from the low pressure space ( 4 ) in the steam room ( 34 ) is possible.

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