WO2014206607A1

WO2014206607A1 - Pump

Info

Publication number: WO2014206607A1
Application number: PCT/EP2014/058921
Authority: WO
Inventors: Achim Koehler
Original assignee: Robert Bosch Gmbh
Priority date: 2013-06-25
Filing date: 2014-04-30
Publication date: 2014-12-31
Also published as: EP3014119B1; DE102013212145A1; CN105339659B; JP6356230B2; KR102139713B1; EP3014119A1; CN105339659A; JP2016524675A; KR20160022831A

Abstract

The invention relates to a high-pressure pump (1) which serves in particular for fuel injection systems of internal combustion engines, comprising a low pressure chamber (4) configured as a power unit chamber (4) and a drive (5) which is disposed at least partially in the low pressure chamber (4). In operation pressure pulses are generated in the low pressure chamber (4) by the drive unit (5). A damping device (30) is provided which on the one hand is coupled to the low pressure chamber (4) and on the other hand is connected to a low pressure level (25) which in operation is located below a pressure (p₁) in the low pressure chamber (4). The damping device (30) has a piston which is displaceable in a piston bore (33) and which not only is acted upon by the pressure ₁ in the low pressure chamber (4) against a spring force of a spring element (36) but also delimits a vapour chamber (34) in the piston bore (33). Furthermore the damping device (30) has a pressure relief means (37) which connects the vapour chamber at least intermittently to the low pressure level (25).

Description

description

title

Pump prior 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 DE 10 2009 003 054 A1 a high-pressure pump for fuel injection systems of air-compressing, self-igniting internal combustion engines is 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 known from DE 10 2009 003 054 A1 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 conveying characteristic or additionally by

Engine part movements volume waves are generated, which in the further

Low-pressure system or another low-pressure region are emitted and there lead to increased pressure loads. This is especially true for

High-pressure pumps with only one pump assembly or with only one high-pressure cylinder with pump piston guided therein. As a result, it may too

Noise or even reduce the 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 are advantageous

Further developments of the pump specified in claim 1 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. In this case, a low-pressure circuit may be formed, which over the

Low pressure chamber of the pump is running. The low-pressure space may in this case be designed as an engine room of the pump, wherein the drive is at least partially in the as

Engine room trained low pressure space is arranged. Thus, lubrication of the drive can be achieved via the low-pressure circuit at the same time.

Pressure pulsations formed by the drive in the engine room

Low pressure space of the pump are generated, are then preferably already damped within the housing of the pump by the at least one damping device. As a result, the effects of such pressure pulsations on other parts of the

Low pressure circuit reduced. Other damping devices used in the

Low-pressure circuit can be provided, thereby can 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 advantageously via the

Low-pressure space at least indirectly to a pump working space one

Pump assembly are performed. The low-pressure space may in particular be the engine room. Possible are also here

Embodiments in which the pump has a plurality of pump assemblies and correspondingly a plurality of pump working spaces to which the fluid, in particular the fuel, is guided via the low-pressure space. It is advantageous that the relief device, a throttle, which connects the vapor space at least indirectly with the low pressure level, and / or a for

Low-pressure level-opening check valve, on the one hand at least indirectly with the vapor space and on the other hand, at least indirectly with the low pressure level is connected has. 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 in an advantageous manner depending on a pulsation frequency and a Pulsationsamplitude and the low pressure level after the throttle tuned so that when expanding the

Steam room the largest possible volume of steam is generated, the

Re-immersion of the piston is available until the complete condensation of the steam as a damping volume, 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, via the check valve and a

Piston leakage dissipated and enforced a volume of vapor that as

Damping volume is available.

These possibilities of damping are inexpensive and maintenance-free, as the

Operability due to 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 whole

Lifespan can be ensured.

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. Of 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

Relief device is integrated in 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 in the

Closing element is integrated. 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

Piston guide 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. 1 shows a high-pressure pump of a fuel injection system in a schematic illustration according to a first exemplary embodiment of the invention;

Fig. 2 is a partial, schematic sectional view of the high-pressure pump shown in Figure 1 according to a second embodiment of the invention.

Fig. 3 is a partial, schematic sectional view of the high-pressure pump shown in Figure 1 according to a third embodiment of the invention.

4 is a partial, schematic sectional view of the high-pressure pump shown in FIG. 1 in accordance with a fourth exemplary embodiment of the invention;

Fig. 5 is a partial, schematic sectional view of the high-pressure pump shown in Fig. 1 according to a fifth embodiment and Fig. 6 is a diagram for explaining the operation of a high-pressure pump according to a possible embodiment of the invention.

EMBODIMENTS OF THE INVENTION FIG. 1 shows a high-pressure pump 1 of 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 ones

Internal combustion engines serve. Furthermore, the high-pressure pump 1 also as

Hydraulic pump designed for other hydraulic applications.

The high-pressure pump 1 has a low-pressure chamber 4 and a drive 5. In this case 5 pressure pulsations in the low-pressure space 4 are generated in operation by the drive. In this embodiment, the low-pressure space 4 is formed by an engine room, in which an axis 6 is arranged with a multiple cam 7 at least partially. The multiple cam 7 of the axis 6 is used to drive a pump piston 8 of a pump assembly 9 of the high-pressure pump 1. Here, a part of a cylinder head 10 is shown schematically, in which a cylinder bore 1 1 is configured. Of the Pump piston 8 is guided in the cylinder bore 11. The actuation of the pump piston 8 by the multiple cam 7 is illustrated by a double arrow 12.

Furthermore, a metering unit 13 is provided, is guided over the operating at low pressure fuel in a pump working chamber 14. The pump working chamber 14 is in this case limited by the pump piston 8 in the cylinder bore 11. During operation, the high-pressure fuel is conducted via an outlet valve 15, for example, to a common rail. By the drive 5, in particular the reciprocating motion of the pump piston 8, 4 pressure pulsations are generated in the low-pressure space. It should be noted that to simplify the illustration of the engine room (low-pressure space) 4 is shown separately from the drive 5, in particular the axis 6, which is at least partially disposed in the engine room 4.

The low-pressure circuit 3 comprises a tank 20 and a prefeed pump 21, which may be configured, for example, as an electric fuel pump 21. By the

Pre-feed pump 21, the fuel is conveyed from the tank 20 via a filter device 22 in the low-pressure chamber 4. The filter device 22 comprises a filter and optionally also a water separator.

From the low-pressure space 4, part of the fuel is led via a housing bearing 23 and a flange bearing 24 to a low-pressure level 25. On the housing bearing 23 and the flange bearing 24, the axis 6 is mounted with the multiple cam 7. The

Housing bearing 23 and the flange bearing 24 are in this case by throttling 23, 24th

illustrates that they act as chokes.

In the low-pressure space 4, for example, a pressure prevails. The low-pressure level 25 has a pressure p ₂ which is less than the pressure. In order to maintain a certain, low pressure p ₂ at the low pressure level 25, a device 26 can optionally be provided. As a result, the pressure p _2, for example, be held slightly above the optionally pressure-relieved tank 20. The device 26 may for example have a throttle or other low pressure limit. Depending on the design of the low-pressure circuit 3, the device 26 may also be omitted. Specifically, already by the length of a return line 27, which leads from the low pressure level 25 to the tank 20, the desired low pressure p ₂ in the low pressure level 25 can be achieved. The high-pressure pump 1 has a damping device 30. Depending on the design of the high pressure pump 1, a plurality of such damping devices 30 may be provided. The damping device 30 is connected on the one hand by means of a line 31 to the low pressure chamber 4 and on the other hand connected to the low pressure level 25. In operation, the low pressure level 25 is at its pressure p ₂ below the pressure in the low pressure space 4. Thus, there is a pressure gradient across the damping device 30 from the low pressure chamber 4 to the low pressure level 25th

When pressure pulsations occur, pressure oscillations occur in the

Low pressure space 4, which triggers a damping by the damping device 30.

For this purpose, the damping device 30 in this embodiment, a piston 32, which serves as a compensating piston 32. The piston 32 is guided displaceably in a piston bore 33. In this embodiment, the piston 32 divides the piston bore 33 into a vapor space 34 and a space 35. The vapor space 34 serves at the same time as a spring space 34, in which a spring element 36 is arranged, which is designed, for example, as a spiral spring 36.

From the space 35 ago the piston 32 is acted upon by the pressure p in the low-pressure chamber 4 against the spring force of the spring element 36. On the other hand, the piston 32 limits the vapor space 34 in the piston bore 33.

The damping device 30 also has a relief device 37, which connects the vapor space 34 with the low pressure level 25. In this embodiment, the relief device 37 includes a check valve 38. The check valve 38 opens in this case to the low pressure level 25 back.

The fuel flow in the low-pressure circuit 3 is illustrated by arrows. Here, between the low pressure chamber 4 and the space 35 of 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 is due to the pressure pulsations to a reduction in the pressure p in

Low pressure chamber 4 comes, then fuel flows from the room 35 in the

Low pressure space 4. As a result, the piston 32 due to the spring force of

Adjusted spring element 36 so that the volume of the vapor space 34 increases. Since the check valve 38 blocks an inflow of fuel into the vapor space 34, a certain amount arises in accordance with the displacement of the piston 32 in the vapor space 34

Vapor volume. The pressure pulsation then generates according to their time course This results in a return 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 32nd

The piston 32 is guided in the piston bore 32 in such a way that a leakage flow from the space 35 connected to the low-pressure space 4 into the vapor space 34 is made possible between the piston 32 and the piston bore 33. The leakage is in this case discharged via the check valve 38 to the low pressure level 25 during operation.

Fig. 2 shows a partial, schematic sectional view of the illustrated in Fig. 1 high-pressure pump 1 according to a second embodiment. Here, a housing part 45 is shown, which is part of a housing 46 of the high pressure pump 1, in which the low-pressure chamber 4 is configured. The housing part 45 may also be the cylinder head 10.

In this embodiment, a tubular sleeve 47 is inserted into the housing part 45, in which the piston bore 33 is configured. Here, a closure element 48 is inserted into the sleeve 47, which closes the piston bore 33 to an outer side 49 of the housing part 45 through. The vapor space 34 is formed between the piston 32 and the closure member 48 in the piston bore 33.

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

In this exemplary embodiment, the relief device 37 has a throttle 51, which opens radially into the piston bore 33. The throttle 51 is configured in the sleeve 47 in this embodiment. In this case, the throttle 51 connects the vapor space 34 with the channel 50.

The throttle effect of the throttle 51 is set so strong that at a

Pressure reduction in the low pressure chamber 4, which is caused by a pressure pulsation and allows adjustment of the piston 32 with the spring force of the spring element 36, up to a provision of the piston 32, which is caused by the pressure increase caused by the following pressure increase in the low pressure chamber 4, temporarily a vapor volume is generated in the vapor space 34. The damping device 30 can be tuned in particular by the spring element 36 and the throttle 51. Here, the throttle effect of the throttle 51 in

Depending on a pulsation frequency and a pulsation amplitude and the low pressure level 25 with the pressure p ₂ after the throttle 51 are tuned so that when expanding the spring element 36 as large a vapor volume is generated in the vapor space 34, the re-immersion of the piston 32 to complete Condensation of the steam is available as a damping volume, without a renewed volume displacement takes place. Fig. 3 shows an excerpts, schematic sectional view of the high-pressure pump 1 shown in Fig. 1 according to a third embodiment. In this

Embodiment, the closure member 48 has a through hole 52. The through hole 52 may be formed at least in sections with a sufficiently small diameter to form the throttle 51. In this way, the throttle 51 can be integrated into the closure element 48. On one side 53 of the

Closure element 48, which faces away from the vapor space 34, a return in the return line 27 is suitably designed. Thus, on the side 53 of the closure element 48, the low pressure level 25 can be ensured with the pressure p ₂ . 4 shows a partial, schematic sectional view of the high-pressure pump 1 shown in FIG. 1 in accordance with a fourth exemplary embodiment. In this

Embodiment, the damping device 30 has a part 54 which is designed as a screw or plug-in part 54 and screwed into the housing part 45

or is inserted. The part 54 has a tubular portion 55 in which the piston bore 33 is formed. The tubular portion 55 of the part 54 is sealed with respect to the housing part 55 with a sealing ring 56.

In the piston bore 33 of the tubular portion 55, the closure element 48 is arranged. Furthermore, a further closure element 57 is provided, which is the

Closes piston bore 33 from the environment. Between the other

Closing element 57 and the closure element 48, the low pressure level 25 is predetermined in a gap 58. The gap 58 is suitably connected to the return line 27. In this embodiment, the check valve 38 is integrated into the closure element 48. In this case, the check valve 38 allows a fuel flow from the vapor space 34 into the gap 58. By this fuel flow, the leakage, which passes into the vapor space 34 due to the leakage flow between the piston 32 and the piston bore 33, are guided to the return line 37.

Fig. 5 shows an excerpt, schematic sectional view of the high pressure pump 1 shown in FIG. 1 according to a fifth embodiment. In this

Embodiment, the piston bore 33 of the part 54 is closed by the closure member 48 from the environment. Further, the tubular portion 55 has at least one radial connection hole 59, 60, wherein in this

Embodiment a plurality of radial connection holes 59, 60 are provided.

Further, in this embodiment, in the housing part 45 of the channel 50 is configured. The channel 50 can be configured for example by a housing bore 50 in the housing part 45. In the channel 50, the check valve 38 is arranged. Thus, the vapor space 34 is connected to the low pressure level 25 via the radial communication bores 59, 60 and the check valve 38.

Fig. 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 in the low-pressure chamber 4 plus the pressure fluctuations caused by pressure pulsations. The pressure pulsations are caused by the drive 5. One possible pressure pulsation is illustrated by curve 61. Thus, a pressure fluctuation occurs around the pressure p in the low-pressure space 4 considered as the mean pressure

However, pressure fluctuations are effectively damped by the damping device 30. As a result, such pressure fluctuations do not affect the rest

Low pressure circuit 3 off. In particular, the functionality of the metering unit 13 is ensured. The invention is not limited to the described embodiments.

Claims

claims

1. pump (1), in particular high-pressure pump (1) for fuel injection systems, with a low-pressure chamber (4) and a drive (5), are generated by the operating pressure pulsations in the low-pressure chamber (4),

characterized,

in that at least one damping device (30) is provided which, on the one hand, is connected at least indirectly to the low-pressure chamber (4) and, on the other hand, to a

Low pressure level (25) is connected, which is in operation under a pressure (p ^ in the low pressure chamber (4) that the damping device (30) one in one

Piston bore (33) displaceable piston (32) which is acted upon on the one hand by the pressure (p ^ in the low pressure chamber (4) against a spring force and on the other hand, a vapor space (34) in the piston bore (33) limited, and a discharge device (37) has, which at least partially connects the vapor space (34) with the low pressure level (25).

2. Pump according to claim 1,

characterized,

in that the relief device (37) has a throttle (51) which connects the vapor space (34) at least indirectly to the low pressure level (25) and / or a check valve (38) which opens towards the low pressure level (25) and which at least indirectly communicates with the

Steam chamber (34) and on the other hand, at least indirectly connected to the low pressure level (25) has.

3. Pump according to claim 2,

characterized,

the throttle (51) of the relief device (37) opens radially into the piston bore (33).

4. Pump according to claim 2,

characterized,

in that a closure element (48) is arranged in the piston bore (33), that the vapor space (34) between the piston (32) and the closure element (48) in the Piston hole (33) is formed and that the throttle (51) of the relief device (37) in the closure element (48) is integrated.

5. Pump according to one of claims 2 to 4,

characterized,

that a throttle effect of the throttle (51) is set so strong that at a pressure reduction in the low-pressure chamber (4), which is caused by a pressure pulsation and an adjustment of the piston (32) with the spring force allows up to a

Resetting the piston (32), which is effected by the pressure increase caused by the following pressure increase in the low pressure chamber (4), temporarily a volume of vapor in the vapor space (34) can be generated.

6. Pump according to one of claims 2 to 5,

characterized,

in that the piston bore (33) is arranged in a housing (46), that a channel (50) is formed in the housing (46) which opens into the vapor space (34) of the piston bore (33), and in that the check valve (38 ) is disposed in the channel (50).

7. Pump according to one of claims 2 to 5,

characterized,

in that a closure element (48) is arranged in the piston bore (33), that the vapor space (34) is formed between the piston (32) and the closure element (48) in the piston bore (33), and that the check valve (38) engages in the

Closure element (48) is integrated.

8. Pump according to one of claims 1 to 7,

characterized,

in that a spring element (36), which acts on the piston (32) with the spring force, is arranged in the vapor space (34).

9. Pump according to one of claims 1 to 8,

characterized,

in that the low-pressure chamber (4) is designed as an engine compartment (4) and that the drive (5) is arranged at least partially in the low-pressure space (4) designed as engine compartment (4) and / or at least indirectly via the low-pressure chamber (4) to a pump working space (14) is feasible.

10. Pump according to one of claims 1 to 9, characterized,

in that the piston (32) is guided in the piston bore (33) such that a leakage flow from the low-pressure chamber (4) into the vapor space (34) is made possible between the piston (32) and the piston bore (33).