EP2888469A1

EP2888469A1 - Common rail system

Info

Publication number: EP2888469A1
Application number: EP13750553.3A
Authority: EP
Inventors: Florian Schulz; Gerd Strobel; Wolfgang Knöbel
Original assignee: Kendrion Villingen GmbH
Current assignee: Kendrion Villingen GmbH
Priority date: 2012-08-23
Filing date: 2013-08-14
Publication date: 2015-07-01
Anticipated expiration: 2033-08-14
Also published as: US9765741B2; US20150167611A1; WO2014029676A1; CN104583577A; ES2734990T3; CN104583577B; EP2888469B1; DE102012107764A1

Abstract

The invention relates to a common rail system (CRS) for an internal combustion engine of a vehicle, comprising a high-pressure pump (HP) which delivers highly pressurized fuel to a high-pressure accumulator (R), from which the fuel is fed to at least one injection valve (Inj) of the internal combustion engine, a low-pressure pump (NP) for conveying fuel from a fuel container (KB) via a conveying line (L2) to the high-pressure pump (HP), a flow control valve as an electromagnetic switching valve which is arranged in the conveying line (L2) for controlling the fuel quantity which is fed by the high-pressure pump (HP) to the high-pressure accumulator (R); it is provided according to the invention that the flow control valve is configured as a ball seat valve (VNO) with an inlet opening (1d) which is connected to the low-pressure pump (NP) and an outlet opening (1e) which is connected to the high-pressure pump (HP), which ball seat valve (VNO) is open in the de-energized state.

Description

Common Rail System

The invention relates to a common rail system for an internal combustion engine of a vehicle according to the preamble of patent claim 1.

Common rail systems as Kraftstoffeinsprit zsysteme are ^¬ known, which have a high-pressure pump for providing high-pressure fuel for a high-pressure accumulator (common rail) and a low-pressure pump as a prefeed pump, which promotes the fuel from a fuel tank via a feed line to the high-pressure pump wherein the power supplied by the high pressure pump to the high pressure storage power ^¬ molar flow control valve controlled by a valve disposed in the feed line through and the metered from the Durchflussregelven ^¬ til fuel quantity is acted upon by the high pressure pump with the corresponding high pressure.

Such a common rail system CRS is shown schematically in FIG. Thereafter, this common rail system CRS consists of a high-pressure accumulator R, from which injectors Inj an internal combustion engine (not shown), for example. A diesel engine are supplied with fuel. The high pressure accumulator R is connected via a high pressure line LI with a high pressure pump HP, which is driven by a Elektromo ^¬ tor Ml. From a fuel tank KB via a feed line L2 fuel for a flow control valve VNC is conveyed by means of a driven by an electric motor M2 low-pressure pump NP, which is formed as electromagnetic ^¬ table switching valve of the type slide valve and is closed in the currentless state ( "Normally Clo sed "). On the output side, this slide valve VNC is connected to the high-pressure pump HP.

Finally, a high-pressure control valve HPV connects the high-pressure accumulator R via a pressure relief line L3 to the outlet side of the low-pressure pump NP. This formed as electromagnetic ^¬ ULTRASONIC switching valve high-pressure control valve HPV is used for rapid pressure reduction in the high-pressure accumulator R. This high-pressure control valve HPV is necessary because in a disadvantageous manner, the spool valve VNC not 100% Le ^¬ ckagefreiheit has. This leakage has its cause in the required for the displacement of the slide element game between this slide element and the valve body. The result is that arrives in the shift operation, fuel in the high ^¬ pressure pump HP, and is compacted there, increases with the result that, in the high-pressure reservoir R of the pressure when the injectors Inj lie no fuel to the internal combustion engine ^¬ away, so a consumer with the high-pressure accumulator R is connected. With the HPV high-pressure control valve, the pressure is released in such operating states.

Both the flow control valve VNC, the high and low ^¬ pressure pump HP and NP, the high-pressure control valve HPV and the injection valves Inj are controlled by a control device (not shown) or regulated.

A common rail system corresponding to FIG. 4 is known, for example, from DE 60 2005 003 427 T2, in which a slide valve which is closed in the non-energized state is used as the flow control valve. To the occurring when using conventional slide valves in addition to the lack of freedom from leaks, namely lack of centering of the Slider element in the valve chamber and the consequent man ^¬ ing slipperiness, which leads to a higher wear with high abrasion to counteract, an improved construction of a slide valve is proposed. This improved construction relates to the design of the slider element.

The disadvantage of the lack of freedom from leakage when using a slide valve in a common rail system is eliminated according to DE 198 46 157 AI in that the output side of the flow control valve is provided both a recirculated to the Kraftstoffbe ^¬ container return line and a differential pressure valve is connected, which is connected to the suction valves of a high pressure pump. This ensures that the high-pressure pump in the operating state "zero delivery" does not deliver fuel, since the differential pressure valve from the leakage flow of the flow control valve can not be overwinter ^¬ . Another disadvantage of the use of "Normally Closed" -

Slide valves in common rail systems is that in the event of a defect or failure of such a slide ^¬ valve no fuel in the rail, so in the high ^¬ pressure accumulator can be promoted and thus no further operation of the internal combustion engine no longer is possible.

The invention has the object of developing common rail system of the type mentioned in such a way that the known from the prior art disadvantages are avoided, in particular a simple structure with few components made ^¬ light. This object is achieved by a common rail system having the features of patent claim 1.

This common rail system for an internal combustion engine of a vehicle includes a high pressure pump which supplies high pressure be ^¬ aufschlagten fuel to a high pressure accumulator, is from which the fuel is supplied to at least one injection valve of the internal combustion engine further includes a ^low-¬ pressure pump for feeding fuel from a Fuel tank via a delivery line to the high-pressure pump and finally a flow control valve as an electromagnetic switching valve, which in the delivery line for controlling the supplied from the high-pressure pump to the high-pressure accumulator

Fuel quantity is arranged and is characterized according to the invention characterized in that the flow control valve is formed as a ball seat ^¬ valve with an inlet connected to the low-pressure pump inlet ^¬ opening and connected to the high-pressure pump outlet ^¬ opening, which is ge ^¬ opens in the de-energized state.

Such an inventive common rail system with a Ku ^¬ gelelsitzventil which is open in the de-energized state

("Normally Open"), during operation of the internal combustion engine ^{¬ at} least no malfunction of the internal combustion engine, if this ball seat valve is defective or fails.

A further advantage is that such ball ^¬ seat valve having an electromagnetic switching valve is no leakage, so that "zero-promoting" no fuel via the high pressure pump is fed into the high-pressure accumulator in the operating state. This means that to the at the most ^¬ 4 required high-pressure control valve HPV can be omitted For reasons, it is sufficient to provide only a mechanical pressure relief valve instead of this Hochdruckregelven ^¬ tils HPV. The ^¬ ses mechanical pressure relief valve opens only in the "worst case", eg. When the ball seat valve would bind.

This reduces the number of components required compared to known common rail systems according to the prior art, but at least a simpler structure is realized with the common rail system according to the invention, since a complex high-pressure control valve is eliminated.

Such ball seat valves as electromagnetic switching valves, which are open in the de-energized state, are known, for example, from DE 40 41 377 AI.

In a further development of the invention, the ball seat valve is formed with a valve seat and a valve ball, ^¬ art that in the energized state of the ball seat valve by pressurization by the low pressure pump, the Ventilku- gel rests on the valve seat under closure of the inlet opening.

Since the valve ball is located on the pressure side and is pressed exclusively by the fluid pressure of the low pressure pump in the energized state of the ball seat valve against the valve seat, eliminating spring elements on the pressure side and there is therefore no need

Spring tolerances are respected or adjusted. It is achieved a high degree of tightness and thus ensures a complete freedom Le ^¬ ckagefreiheit. In one embodiment of the invention, the ball seat valve is formed with a spring-biased valve tappet, such that in order to open the inlet opening of the valve tappet in the non-energized state of the ball seat valve, the valve core is opened. gel stands by the valve seat lifting operative connection. Preferably, the ball seat valve has a relative to a pole core displaceable armature, which receives the valve stem centrally. Thus, the armature, which receives the valve stem, working against a compression spring, which is located on the non-pressurized side.

This leads to a mechanical decoupling of armature or valve tappet and valve ball, whereby the loads of the armature and of the valve tappet are reduced under vibrations.

According to a further embodiment of the invention, the pole core has a central bore for receiving a pressure spring, wherein at one end the compression spring is supported against the armature and at the other end is supported against a closure part of the pole core closing the bore on the armature-facing side of the pole core.

With such a closing part which is inserted either by means of a press fit or a threaded connection in the bore of the pole core, can be adjusted the spring force acting on the valve stem compression spring of the closing part in the pole core in dependence on the penetration depth ^¬ A. Finally, it is provided according to a last embodiment of the invention that the armature is formed with a decentralized bore which connects the bore of the pole core with egg ^¬ nem valve ball-side valve chamber. This pressure equalization of the two rooms is achieved via this decentralized bore of the armature and thereby prevents pressure pulsations and allows uniform filling of the working spaces of the high-pressure ^¬ pump. The invention will now be described in detail with reference to an Ausführungsbei ^¬ game with reference to the accompanying figures. 1 shows a schematic representation of a common rail

System with a ball seat valve as Durchflußre ^¬ gelventil according to an embodiment of the invention,

Figure 2 is an axial longitudinal section of the ball seat valve of

Common rail system according to FIG. 1,

Figure 3 is a characteristic of the ball seat valve of Figure 2, and

Figure 4 is a schematic representation of a common rail system with a slide valve as a flow control ^¬ valve according to the prior art.

The common rail system CRS according to FIG. 1 consists of a high-pressure accumulator R with high-pressure fuel, which is supplied by means of injectors Inj to an internal combustion engine (not shown).

The high pressure accumulator R is connected via a high pressure line LI with a high pressure pump HP, which is driven by an electric motor Ml.

A driven by an electric motor M2 low-pressure pump NP delivers fuel from a fuel tank KB, which is supplied via a delivery line L2 of the high-pressure pump HP, wherein in this delivery line L2 a ball seat valve VNO is arranged as a flow control valve, which as electro ^¬ magnetic switching valve in the de-energized state is open. With this ball seat valve VNO the amount of fuel is ge ^¬ controls that leads the high-pressure pump HP the high-pressure accumulator R ^¬ . Finally, the high-pressure accumulator R is connected via a mechanical overpressure valve VÜ and a pressure relief line L3 to the delivery line L2 between the low-pressure pump NP and the ball poppet valve VNO. This pressure relief valve VÜ is le ^¬ diglich required for safety reasons, in order to be able to discharge an overpressure in the high-pressure accumulator R in the case of a "worst case".

Finally, this common rail system CRS according to FIG. 1 also includes a control unit (not shown), which includes the low-pressure pump NP, the high-pressure pump HP, the ball seat valve VNO and the injectors Inj via control lines (not shown) as a function of the sensor signals and the operating state the internal combustion engine controls. This invention common rail system CRS is characterized by the use of a ball seat valve VNO as a flow control valve through ^¬ of which is open in the currentless state, and controls the high pressure pump HP supplied fuel volume flow.

As a result of such a ball seat valve VNO being leak-free, no fuel is supplied from the ball seat valve VNO to the high-pressure pump HP in the operating state "zero delivery." Therefore, a high-pressure control valve HPV as required in the prior art according to FIG 1, for safety reasons, only one mechanical overpressure valve VÜ is provided, which has a connection tion between the high-pressure accumulator R and the delivery line L2 between the low-pressure pump NP and the ball seat valve VNO can produce. In the idle state, ie in the de-energized state, the ball ^¬ seat valve VNO is open, so that in case of failure or failure of this ball seat valve VNO still funded by the Never ^¬ derdruckpumpe NP fuel can be delivered to the high-pressure pump, so that at least malfunction aptly the internal combustion engine are excluded.

Such ball seat valve VNO is shown in FIG 2, which has a centrally mounted pole core 8 receives in egg ^¬ nem valve housing 20 which is partially enclosed by an annular coil, comprising a disposed on a bobbin 15 coil winding sixteenth

Connected to the pole core 8 via a connecting ring 13 is a valve body 1 with a central bore la, which forms a central receiving space 1b for an armature 5 on the pole core side. The armature 5 carries centrally a valve stem 6, the pole core side, the end face of the armature 5 projects beyond and projects into a central bore 8 a of the pole core 8. This bore 8a is closed at the end by a closure 11, wherein a compression spring 9 arranged in the bore 8a of the pole core 8 is supported on the one hand against this closure 11 and on the other hand against the adjacent end face of the armature 5 via a spring plate 7 resting thereon. The bore 8a of the pole core 8 goes on the anchor side in a abge ^¬ set cylindrical bore 8b, the diameter of which corresponds to the diameter of the armature 5, so that the armature 5 in energizing the coil winding 16 in this bore 8b of Polkerns 8 is pulled against the spring force of the prestressed compression spring 9 to the pole face of the pole core 8. The surrounding this zy ^¬- cylindrical bore ring 8c is formed as a control cone with an outer cone which serves to set the magnetic force-stroke characteristic when the armature 5 from its rest position corresponding to the position shown in Figure 2 by energizing the coil winding 16 in the direction the pole face of the pole core 8 is pulled. The armature 5 is received by a sleeve 10 which extends over the region of the bore 1b and the connecting ^ring 13 he ^¬ stretches.

On the pole core side facing away from the armature 5, the bore la of the valve body 1 extends into a valve chamber lc and ends up in an inlet opening ld, which is connected to the low-pressure pump NP.

The adjoining this inlet opening ld valve space lc takes a ball cage 3 for receiving a valve ball 4 and an adjoining valve seat 2 for the valve ball 4.

In an lc of the valve chamber adjoining region of the cen- eral bore la of the valve body 1, two dia ^¬ diametrically opposed radial bores le as Auslassöff ^¬ voltage le at least are provided, which led to the high pressure pump HP ^¬ the. The valve stem 6, starting from the pole core facing away from the end face of the armature 5 has such a length that in the rest position of the ball seat valve VNO shown in Figure 2, ie in the de-energized state, the compression spring 9, the anchor fifth completely pushes into the bore lb of the valve body 1 in the direction of the inlet opening ld, while the valve stem 6 with a needle tip 6a lifts the valve ball 4 from the valve seat 2, so that the passage between the inlet opening ld and the outlet opening le is released.

The armature 5 has a non-centric, parallel to ^{Längsach ¬} se extending bore 5a, which connects the two end faces. Thus, the valve chamber lc and the outlet openings le are connected to the bore 8a of the pole core 8, so that a pressure equalization between these spaces can take place during operation of the ball seat valve VNO, or builds up no pressure difference between these spaces. For mounting the ball seat valve VNO, for example, on the high-pressure pump ^¬ HP, a flange 12 is provided. In a corresponding connection O-rings 14 and 21 of the valve body 1 are provided as sealing rings. The bobbin 16 is overmolded to form a connector 17 receiving plastic body 17, wherein a sealing washer 19, the tightness against ^¬ over the environment produces.

If, starting the rest position the ball seat valve VCO according Fi ^¬ gur 2, the coil winding is energized 16, the armature 5 is pulled together with the valve stem 6 in the direction of the pole core 8 against the spring force of the compression spring 9, so that due to the intake-side pressure, the valve ball 4 pressed into the valve seat 2 and thereby the ball seat valve VNO is closed. When mounting the ball seat valve VNO, a spring force ^¬ adjustment of the compression spring 9, with which the armature 5 is biased, are performed. For this purpose, the closure 11a closing the bore 8a of the pole core 8 can be closed at the end. be introduced deep into the hole 8a different or formed with different lengths, so that in this way different installation lengths for the compression spring 9 arise. For introducing the closure 11 in the bore 8a, a press fit or a threaded connection can be provided.

By different disc springs 7 can also be easily a stroke adjustment of the armature 5 are made.

A schematic curve of the ball seat valve according VNO Fi gur ^¬ 2 shows Figure 3, which indicates the volumetric flow Q as a function of the current strength I. In the de-energized state or at low currents, a high flow or volumetric flow of fluid, that is to say fuel, is achieved which decreases with increasing current flow, that is to say with increasing current intensity up to the value zero, ie until the ball seat valve VNO is closed. Because of the hysteresis properties of the electromagnet, the characteristic doubles in the middle range.

Reference sign list

1 valve body

la centric bore of the valve body 1 lb receiving space of the valve body 1 lc valve chamber

ld inlet opening

le outlet opening

2 valve seat

3 ball cage

4 valve ball

5 anchors

5a decentralized bore of the armature 5

6 valve tappets

7 spring plate

8 polkernels

8a bore of the pole core 8

8b bore of the pole core 8

8c control cone of the pole core 8

9 compression spring

10 sleeve

11 Closure of the pole core 8

12 flange

13 connecting ring

14 O-ring

15 bobbin

16 coil winding

17 plastic body

18 connector

19 sealing washer

20 valve housing

21 O-ring CRS common rail system

HP high pressure pump

HPV high pressure control valve

In ector

KB fuel ehälter

Ml electric motor of HP high pressure pump

M2 Electric motor of low pressure pump NP

NP low pressure pump

LI high pressure line

L2 support line

L3 pressure tap line

R high pressure spreader

VNC gate valve

VNO ball seat valve

VÜ mechanical overpressure valve

Claims

Common-rail system (CRS) for an internal combustion engine ei ^¬ nes vehicle, comprising:

- a high pressure pump (HP), which provides beauf ^¬ estimated fuel to a high-pressure reservoir (R) with high pressure, of which the at least one fuel injection valve ^¬ A (Inj) of the internal combustion engine is supplied,

a low-pressure pump (NP) for conveying fuel from a fuel tank (KB) via a delivery line (L2) to the high-pressure pump (HP),

- A flow control valve as electromagnetic

Switching valve, which in the delivery line (L2) for STEU ^¬ tion of the high pressure pump (HP) the Hochdruckspei ^¬ cher (R) supplied fuel quantity is arranged, characterized in that

is formed, the flow control valve as a ball seat valve (VNO) associated with the low-pressure pump (NP) inlet ^¬ opening (ld) and one with the high pressure pump (HP) ver ^¬-bound outlet opening (le), which is open in the currentless state.

Common rail system (CRS) according to claim 1,

d a d u r c h e c e n c i n e s that

the ball seat valve (VNO) with a valve seat (2) and a valve ball (4) is formed, such that in the energized state of the ball seat valve (VNO) by

Pressurized by the low pressure pump (NP), the valve ball ($) on the valve seat (2) under closure of the inlet opening (ld) is applied. Common rail system (CRS) according to claim 2, characterized in that the ball seat valve (VNO) with a spring-biased valve tappet (6) is formed such that for opening the inlet opening (ld) of the valve stem (6) in the de-energized state of Ball seat valve (VNO) in a valve ball (4) of the valve seat (2) contrasting operative connection.

Common rail system (CRS) according to claim 3,

characterized in that the ball valve (VNO) has a relative to a pole core (8) displaceable armature (5), which receives the Ventilstö ^¬ ßel (6) centrally.

Common rail system (CRS) according to claims 4,

characterized in that the pole core (8) has a central bore (8a) for receiving a compression spring (9), wherein at one end the pressure ^¬ spring (9) is supported against the armature (5) and andernends against a bore (8a ) on the non-armature side of the pole core (8) closing the closure part (11) of the pole core (8) is supported.

Common rail system (CRS) according to claim 3,

That is, the armature (5) is formed with a decentralized bore (5a) which connects the bore (8a) of the pole core (8) with a valve ball-side valve space (lc).