WO2015090961A1

WO2015090961A1 - Fuel supply device of a fuel injection system of an internal combustion engine, and overflow valve for the same

Info

Publication number: WO2015090961A1
Application number: PCT/EP2014/076374
Authority: WO
Inventors: Florian MAGER
Original assignee: Robert Bosch Gmbh
Priority date: 2013-12-19
Filing date: 2014-12-03
Publication date: 2015-06-25
Also published as: EP3084200A1; EP3084200B1; CN105829695A; DE102013226649A1; CN105829695B

Abstract

The invention proposes a fuel supply device of a fuel injection system of an internal combustion engine, and an embodiment of the overflow valve (30) for the same. The fuel supply device has a high-pressure pump (18) in addition to the overflow valve (30). The overflow valve (30) conducts a nonrequired fuel quantity from the high-pressure pump (18) into a spill line (28). The overflow valve (30) has a spring chamber (32) which is hydraulically connected to the spill line (28). For the hydraulic connection of the spring chamber (32) to the spill line (28), a discharge line (29) is provided which is hydraulically connected to a suction side (41) of a Venturi nozzle (40).

Description

description

title

Fuel supply device of a Kraftstoffeinspritzsvstems a

Internal combustion engine and overflow valve to

State of the art

From DE 102010043439 A1 a fuel supply device is a

Fuel injection system of an internal combustion engine with an overflow valve for a metering unit of a high pressure pump known. The overflow valve has a valve housing with a valve control chamber and a spring chamber, wherein the spring chamber is designed as a back space to the valve control chamber. Of the

Valve control chamber is hydraulically connected upstream of the metering unit with a delivery line, through the fuel from a feed pump to

High-pressure pump is promoted. The valve control chamber further has an output which leads into a Absteuerleitung, which with a non-pressurized

Return line is connected. In the valve housing a against the spring force of a compression spring slidably mounted valve piston is housed in

Dependence on a pressure built up by the metering unit in the valve control chamber opens or closes the outlet to the discharge line. When open

Output, the fuel is discharged into the Absteuerleitung and from there back into a tank of the fuel supply device. The spring chamber is connected via a respective hydraulic connection line to the suction side of the high-pressure pump and to the discharge line. The hydraulic connection lines to the suction side of the high-pressure pump and the discharge line each have a throttle.

In novel high-pressure pump concepts, a strong displacement effect occurs in the low-pressure circuit. This creates disturbing pressure pulsations in the

Line system of the fuel supply device. The object of the present invention is to minimize disturbing pressure pulsations in the line system of the fuel supply device.

Disclosure of the invention

The fuel supply device according to the invention and the overflow valve according to the invention with the characterizing features of the independent claims have the advantage that the dynamic behavior of the valve piston of the

Overflow valve is improved in a pulsating environment. This is achieved by the overflow valve over small pressure changes to the

Incoming side performs a synchronous to the stroke frequency of the high-pressure pump movement and thus intake side takes volume and releases. To the

Not to impair the ability to vibrate the valve piston, just here the spill valve should not be hydraulically damped. In addition, the backflow of the spring chamber via the throttle connection is prevented or reduced by the continuous extraction by means of the Venturi nozzle. At the same time prevents transfer of the pulsation from the spring chamber takes place on the return. By connecting the spring chamber to the suction side of the Venturi nozzle, a medium negative pressure is specifically generated within the spring chamber.

This is expected in diesel fuel, an increased air content up to the steam. Since the Kraftstoffpo Ister is reduced in the spring chamber, the pulsation of the fuel tends to decrease in the Absteuerleitung. This effect is particularly advantageous in the case of the one or two-piston high-pressure pumps used, in which particularly strong pulsations occur in the low-pressure circuit. By deriving the fuel leakage from the spring chamber loses that

manufacturing-related clearance between valve piston and cylinder guide to influence.

The essence of the invention is to achieve a discharge of fuel leakage from the spring chamber by the spring chamber is connected to the suction side of a Venturi nozzle to suck the fuel leakage from the spring chamber. In a first embodiment of the fuel supply device, the flow tube of the Venturi nozzle is arranged in a bypass line, wherein the bypass line between a feed line leading to the overflow valve and the discharge line is arranged and wherein an inlet portion of the Flow tube with the supply line and an outlet portion of the flow tube is hydraulically connected to the diversion line.

In a second embodiment of the fuel supply device, the flow tube of the Venturi nozzle is arranged directly in the Absteuerleitung, wherein the formation of the differential pressure in the Venturi nozzle, the flow of

Absteuermenge is exploited in the diversion line. That's it

Flow tube having an inlet portion with an outlet-side connection of the diversion line and with an outlet portion with a return side

Connection of the diversion line hydraulically connected.

In the overflow valve according to the invention, the spring chamber is connected via a formed in the valve housing hydraulic connection line to a suction side of the Venturi nozzle. In an expedient embodiment of the

Overflow valve is the Venturi nozzle with a flow tube and with a

Suction tube disposed within the valve housing. Furthermore, it is conceivable, the Venturi nozzle by means of bore channels directly into the housing of

To integrate high pressure pumps. According to a first embodiment, a passage channel is arranged in the valve housing, in which the flow tube with an inlet portion, a

Constriction and an outlet section is formed.

According to a second embodiment, a Absteuerkanal is arranged in the valve housing, in which the flow tube of the Venturi nozzle with a

Inlet portion, a constriction and an outlet portion is formed. The diversion channel is hydraulically connected to the diversion line.

In both embodiments, the introduced into the valve housing hydraulic connecting line expediently forms the suction tube of the

Venturi nozzle.

Exemplary embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. Show it:

1 shows a fuel supply device with an overflow valve according to a first embodiment,

2 shows a fuel supply device with an overflow valve according to a second embodiment,

3 is a schematic representation of a Venturi nozzle,

4 shows an inventive overflow valve according to FIG. 1 and FIG

5 shows an inventive overflow valve according to FIG. 2.

Figures 1 and 2 show a schematic representation of the

Interaction of the essential components of a

Fuel supply device for a fuel injection system of

Internal combustion engine. The fuel supply device has a

Low pressure circuit 10 with a suction line 11, a delivery line 12 and a Zumessleitung 13 and a high-pressure circuit 14 with a high pressure line 15 and a fuel tank 19. The low pressure circuit 10 further comprises a feed pump 16, which conveys fuel from a tank 17 to a high pressure pump 18. The high pressure pump 18 delivers fuel through the high pressure line 15 to the fuel tank 19, also called rail. The fuel accumulator 19 is optionally connected to a pressure relief valve 21 in connection. To the

Fuel tank 19 are not shown fuel injectors

connected. By means of the fuel injectors fuel is injected under high pressure into a combustion chamber, not shown, of the internal combustion engine. from

Pressure limiting valve 21 and the fuel injectors, not shown, leads a return line 22 back to the pressureless tank 17th

The feed pump 16 operates as a pre-feed pump and sucks fuel through the suction line 11 from the tank 17 and promotes the fuel via a in the

Delivery line 12 arranged fuel filter 23 to an inlet side of

High-pressure pump 18. In the exemplary embodiments illustrated in FIGS. 1 and 2, the fuel supply device cooperates with a controllable metering unit 25. From the metering unit 25, a required amount of fuel is set, which via the Zumessleitung 13 to a suction side of the high-pressure pump 18 is headed. The high-pressure pump 18 pumps the fuel at high pressure via the high-pressure line 15 into the fuel accumulator 19.

By means of the metering line 13, the high pressure pump 18 is required

Amount of fuel provided, which in turn is necessary to in the

Fuel tank 19 amount of fuel delivered to the needs of

Adapt internal combustion engine. In addition, others are

High-pressure pump concepts in use that make do without metering unit 25 and work, for example, with an electrically controllable suction valve.

In the delivery line 12, an overflow valve 30 is arranged upstream of the metering unit 25. The overflow valve 30 has a valve control chamber 31 and a

Spring chamber 32, wherein the spring chamber 32 is formed as a back space to the valve control chamber 31. Further details of the overflow valve 30 will be described later in connection with FIGS. 4 and 5. The valve control chamber 31 is on the inlet side via a supply line 27 to the delivery line 12 and the outlet side via a discharge line 28 to the return line 22 and the tank 17 hydraulically in communication. The

Overflow valve 30 serves to those not required by the high-pressure pump 18

Amount of fuel via the diversion line 28 in the return line 22 and the tank 17 abzusteuern or deduce.

In the spring chamber 32 of the spill valve 30 performs a hydraulic connection, which is hereinafter referred to as discharge line 29. The discharge line 29 is connected to a suction side 41 of a Venturi nozzle 40. By means of the Venturi nozzle 40 29 fuel leakage from the spring chamber 32 is sucked through the discharge line and into the

Absteuerleitung 28 derived.

According to FIG. 3, the venturi nozzle 40 comprises on the suction side 41 a suction pipe 42 and a flow pipe 43 with an inlet section 44, a constriction 45 and a

In the constriction 45, the suction pipe 42 opens. This creates due to the principle of action of the Venturi nozzle 40, a negative pressure in the suction pipe 42, which is transmitted via the discharge line 29 to the spring chamber 32, which in turn the accumulating in the spring chamber 32 fuel leakage the same sucked and discharged into the diversion line 28. In the embodiment in Figure 1, the Venturi nozzle 40 is connected to the flow tube 43 to a bypass line 38 which extends between supply line 27 and Absteuerleitung 28. The bypass line 38 has a leading to the inlet portion 44

inlet-side section 38.1 and an outlet section 46 leading away outlet-side section 38.2. The inlet-side section 38.1 is hydraulically connected to the supply line 27 and the outlet-side section 38.2 is connected to the discharge line 28. Due to the principle of action of the venturi nozzle 40, a suction effect is created in the suction pipe 42, so that the fuel is sucked out of the spring chamber 32 via the suction pipe 42 and the discharge line 29, discharged into the outlet-side section 38.2 of the bypass line 38 and further discharged into the discharge line 28.

In the embodiment in Figure 2, the Venturi nozzle 40 is arranged with the flow tube 43 in the Absteuerleitung 28 by the inlet portion 44 with a

Valve control chamber side section 28.1 to a Absteuerausgang the spill valve 30 and the outlet portion 46 to a return-side section 28.2 of

Absteuerleitung 28 is connected. The function of the Absteuerausgangs will be explained later in connection with the description of Figure 4 and 5 in more detail. Again, the discharge line 29 is connected to the suction pipe 42 of the Venturi nozzle 40. In this case, the required negative pressure is generated by utilizing the flow of Absteuermenge in the diversion line 28, so that here too the fuel leakage over the

Suction pipe 42 is sucked out of the spring chamber 32 and discharged via the discharge line 29. The fuel leakage passes through the outlet section 46 of the

Flow tube 43 in the return-side section 28.2 of the diversion line 28th

Figures 4 and 5 show the spill valve 30 with a valve housing 33, in which, for example, the Venturi nozzle 40 is integrated. In the valve housing 33, the valve control chamber 31 is formed, in which an input 34 and at least one output 35 open, wherein the output 35 forms the already mentioned Absteuerausgang. At the input 34, the supply line 27 and the output 35, the discharge line 28 is connected. The valve control chamber 31 is a against the spring force of a compression spring 37 slidably disposed valve piston 36 exposed, depending on the pressure built up in the valve control chamber 31, the output 35 opens or closes by means of a control edge to the discharge line 28. The valve piston 36 is against the Spring force of the compression spring 37 axially displaced, with increasing fuel pressure in the valve control chamber 31, the control edge of the valve piston 36, the output 35, as shown in Figure 4 and 5, releases. As a result, a quantity of fuel which is not required by the high-pressure pump 18 is discharged as a discharge quantity from the delivery line 12 via the discharge line 28 into the return line 22 and the tank 17.

The compression spring 37 is disposed within the valve housing 33 in the spring chamber 32, which is formed as a back space to the valve control chamber 31. About guiding column of

Valve piston 36 flows fuel leakage from the valve control chamber 31 in the spring chamber 32, wherein the accumulating in the spring chamber 32 fuel leakage as already described by means of the Venturi nozzle 40 is sucked off and discharged into the discharge line 28.

FIG. 4 shows the overflow valve 30 according to a first embodiment, which corresponds to the application in the fuel supply device according to FIG. In this overflow valve 30 are in the valve housing 33 a Absteuerkanal 51 and a

Passage channel 52 is arranged, which are preferably introduced in each case in the axial direction in the valve housing 33. The diversion channel 51 has a hydraulic connection to the outlet 35 and is connected to the diversion line 28. The passageway 52 includes the flow tube 43 of the venturi 40 having the inlet portion 44, the throat 45, and the outlet portion 46

Passage channel 52, the bypass line 38 is connected according to Figure 1, wherein the inlet-side portion 38.1 leads to the inlet portion 44 and the outlet-side portion 38.2 to the outlet portion 46. A hydraulic connecting line 53 leads from the spring chamber 32 to the suction side 41 of the Venturi nozzle 40 and communicates hydraulically with the suction pipe 42. The hydraulic connection line 53 in this case runs essentially transversely to the passage channel 52 through the valve housing 33 and simultaneously forms, for example, the suction tube 42 of the Venturi nozzle 40. The hydraulic connection line 53 or the suction tube 42 thus forms the discharge line hydraulically connected to the spring chamber 32 29 according to FIG. 1

FIG. 5 shows the overflow valve 30 according to a second exemplary embodiment which corresponds to the application in the fuel supply device according to FIG. In this overflow valve 30, the Absteuerkanal 51 is also arranged in the valve housing 33, which is hydraulically connected to the output 35 and connected to the spill line 28. In this case, the venturi nozzle 40 is arranged inside the diversion channel 51, wherein the flow tube 43 forms a section of the diversion channel 51 with the inlet section 44, the constriction 45 and the outlet section 46. A hydraulic connecting line 58 leads from the spring chamber 32 to the suction side 41 of the Venturi nozzle 40 and communicates hydraulically with the suction pipe 42. The hydraulic connecting line 58 extends substantially transversely to the

Absteuerkanal 51 through the valve housing 33 and forms, as in the embodiment in Figure 4 at the same time the suction pipe 42 of the Venturi nozzle 40. The hydraulic

Connecting line 58 and the suction pipe 42 thus forms the discharge line 29 hydraulically connected to the spring chamber 32 according to FIG. 2.

Claims

claims

1. Fuel supply device of a fuel injection system a

Internal combustion engine with an overflow valve (30), wherein the spill valve (30) discharges an amount of fuel into a Absteuerleitung (28), and wherein the

Overflow valve (30) has a spring chamber (32) which is hydraulically connected to the diversion line (28), characterized in that for the hydraulic connection of the spring chamber (32) with the Absteuerleitung (28) a discharge line (29) is provided hydraulically connected to a suction side (41) of a Venturi nozzle (40).

2. Fuel injection system according to claim 1, characterized in that the Venturi nozzle (40) with a flow tube (43) in a bypass line (38) is arranged, which between one of the overflow valve (30) leading

Supply line (27) and the Absteuerleitung (28) is arranged.

3. Fuel injection system according to claim 1, characterized in that the Venturi nozzle (40) with a flow tube (43) in the Absteuerleitung (28) is arranged.

4. Overflow valve with a valve housing (33), in which a valve control chamber (31) and a spring chamber (32) are arranged, wherein the valve control chamber (31) has an input (34) and at least one output (35), wherein the input ( 34) with a delivery line (12) and the output (35) with a discharge line (28) is hydraulically connected, characterized in that the spring chamber (32) in the valve housing (33) formed hydraulic connection line (53,

58) is connected to a suction side (41) of a Venturi nozzle (40).

5. overflow valve according to claim 4, characterized in that the Venturi nozzle (40) with a flow tube (43) and a suction pipe (42) within the valve housing (33) is arranged.

6. overflow valve according to claim 5, characterized in that in

Valve housing (33), a passage channel (52) is arranged, in which the flow tube (43) of the venturi nozzle (40) is formed, and in that the passage channel (52), a bypass line (38) is connected, which the flow tube (43 ) with a leading to the input (34) supply line (27) and with the discharge line (28) connects hydraulically.

7. overflow valve according to claim 5, characterized in that in

Valve housing (33) a Absteuerkanal (51) is arranged, in which the

Flow tube (43) of the Venturi nozzle (40) is formed, and that the

Absteuerkanal (51) with the diversion line (28) is hydraulically connected.

8. Overflow valve according to one of claims 4 to 7, characterized in that the hydraulic connecting line (53, 58) forms the suction pipe (42) of the venturi nozzle (40).