WO2017063860A1

WO2017063860A1 - Metering device

Info

Publication number: WO2017063860A1
Application number: PCT/EP2016/072891
Authority: WO
Inventors: Charlotte Summerer; Holger Dietzhausen; Gellert Elsoe; Thilo Kreher
Original assignee: Robert Bosch Gmbh
Priority date: 2015-10-14
Filing date: 2016-09-27
Publication date: 2017-04-20
Also published as: DE102015219894A1

Abstract

The invention relates to a metering device (10) for introducing a reduction means into an exhaust gas pipe of an internal combustion engine, comprising a valve unit (80) and a receiving device (50) for receiving the valve unit (80), wherein the receiving device (50) and the valve unit (80) extend along an axis (X) in the axial direction, and wherein, at a resting temperature, a length of the receiving device (50) in the axial direction is at least approximately equal to a length of the valve unit (80) in the axial direction. The receiving device (50) and the valve unit (80) are designed in such a way that the difference between a length change of the valve unit (80) in the axial direction, as a result of thermal expansion at a valve temperature, and a length change of the receiving device (50) in the axial direction, as a result of thermal expansion at a receiving temperature, reaches at most a maximum ratio value relative to the length of the valve unit (80) at a resting temperature.

Description

Dosiervorrichtunci

The invention relates to a metering device for introducing a

Reducing agent in an exhaust pipe of an internal combustion engine, wherein the metering device comprises a valve unit and a receiving device for

Inclusion of the valve unit comprises.

State of the art

For exhaust aftertreatment in internal combustion engines of motor vehicles, especially in diesel engines, it is known in an exhaust pipe of the

Internal combustion engine, a liquid medium, in particular a urea solution, which is also referred to as AdBlue® to bring. These are

Dosing devices are known, which are attached to the exhaust pipe and inject the medium into the exhaust pipe.

A generic metering device is known from DE 10 2013 224 739 A1. The metering device comprises an injection valve and a

Receiving device for receiving the injection valve. The injection valve and the receiving device are attached to an exhaust pipe and extend in the radial direction away from the exhaust pipe. Between the injection valve and the receiving device, a strain compensation element is provided, which different length changes of the receiving device and the injection valve due to thermal expansion at elevated

Working temperature compensated. The expansion compensation element is configured, for example, as a plate spring or as a bellows.

From DE 10 2008 041 486 a metering device is known, which contains a metering valve for injecting a reducing agent into the exhaust gas region and is received by a holding device or an adapter, by means of which a connection to the exhaust gas line takes place. To that To be able to introduce reducing agent optimally into the exhaust gas, the

Dosing be positioned as close to the hot exhaust line, wherein maximum temperatures of 700 ° C can be achieved in the exhaust system of internal combustion engines. Due to this inevitably high heat input into the dosing, there is a risk of overheating of the materials, such as those for insulation and seals, which the

Functioning of the dosing unit permanently impaired. For reasons of component strength and material protection against overheating cooling devices are known which a not to be exceeded limit temperature of

Should ensure dosing of about 150 ° C.

From DE 10 2009 047 375 AI a metering module for dosing a reducing agent in the exhaust system of an internal combustion engine is apparent, which is associated with a cooling device. In addition to passive cooling by cooling ribs on the dosing module, a cooling body filled with a fluid is used. For example, a cooling housing comprises a metal sleeve and plastic parts, wherein it may be designed in several parts and is sealed by means of O-rings and is mounted on a receiving sleeve of the dosing.

From WO 2012/049175 a holder for an injector is known, for example for introducing a liquid substance into an exhaust gas of an internal combustion engine, wherein the injector is completely received in a base body and a cap. The main body is formed from interconnected sheets, for example by a soldering or

Welded joint, which together form an annular chamber, wherein the injector received therein is radially enclosed by this and so on

Represents a heat barrier. The annular chamber, which is partially bounded by the housing of the injector, is acted upon by a cooling medium. Of the

Body and the housing of the injector are glued together in the contact areas or positively connected by crimping. The

Tightness of the system is achieved by at least one additional adhesive bonding gasket. The use of elastomers for

Sealing, storage and / or insulation limits the maximum permissible

Temperature of the dosing modules. Disclosure of the invention

It is a metering device for introducing a reducing agent into an exhaust pipe of an internal combustion engine, proposed, which comprises a valve unit and a receiving device for receiving the valve unit. In this case, the receiving device and the valve unit extend along an axis in the axial direction, wherein at a rest temperature, a length of the receiving device in the axial direction is at least approximately equal to a length of the valve unit in the axial direction. The quiescent temperature corresponds, for example, the usual room temperature of 20 ° C.

According to the invention, the receiving device and the valve unit are designed such that the difference of a change in length of the valve unit in the axial direction due to thermal expansion at a valve temperature and a change in length of the receiving device in the axial direction due to thermal expansion at a receiving temperature at most a maximum ratio relative to the length of the valve unit

Standby temperature reached. This means that the receiving device and the valve unit expand in the case of operating temperatures expected during operation of the metering device approximately equally in the axial direction or shrink approximately identically. By expansion is meant herein an expansion with increasing temperature as well as a shrinking with decreasing temperature.

In the corresponding embodiment of the recording device and the

Valve unit is preferably assumed that the valve temperature is in a range of 60 K below and 200 K above the rest temperature, and that the recording temperature is in a range of 60 K below and 200 K above the rest temperature, and that a

Temperature difference between the valve temperature and the

Maximum recording temperature is 100 K.

In the training or interpretation of the recording device and the

Valve unit can also be based on discrete working temperatures. For example, in the formation of the receiving device and the Valve unit can be assumed that the valve temperature is 100 ° C and thus by 80 K greater than the assumed rest temperature of 20 ° C, and that the intake temperature is 80 ° C and is thus 60 K greater than the assumed rest temperature of 20 ° C is.

For example, in the embodiment of the receiving device and the valve unit, it can also be assumed that the valve temperature and the intake temperature are at most or exactly 100 ° C. and are thus 80 K greater than the assumed rest temperature of 20 ° C.

Preferably, in the design of the receiving device and the valve unit, it is assumed that the receiving temperature of the

Receiving device is less than or equal to the valve temperature of the valve unit. This relationship arises in particular when the

Cradle is structurally more effective cooled than the

Valve unit. Under certain circumstances, however, the

Recording temperature to be greater than the valve temperature.

In the corresponding embodiment of the recording device and the

Valve unit is preferably assumed that the maximum

Ratio, which the difference of the change in length of the valve unit and the change in length of the receiving device relative to the length of the

Valve unit at rest temperature in the axial direction due to thermal

Expansion reached at most, less than 2% o. Said numerical value for the maximum ratio value depends on expected voltages in the

Materials of the valve unit and the receiving device and is therefore particularly dependent on their material properties and their geometric properties. Depending on the materials used, the maximum ratio can also be, for example, 1.5% o or 1.2% o or l% o.

Preferably, the valve unit is at least approximately rotationally symmetrical to the axis along which the valve unit extends in the axial direction. Is the metering device to an exhaust pipe a

Attached combustion engine, this axis is preferably perpendicular to a central axis of the exhaust pipe. Preferably, the receiving device is at least approximately rotationally symmetrical to the axis along which the valve unit extends in the axial direction. If the metering device is attached to an exhaust pipe of an internal combustion engine, this axis preferably extends at right angles to a central axis of the exhaust pipe.

Advantageously, the receiving device encloses the valve unit in

Radial direction with respect to the axis along which the valve unit and the receiving device extend in the axial direction. By such a structure, an effective liquid cooling of the metering device and in particular the valve unit is possible.

According to an advantageous embodiment of the invention, the

Receiving device and the valve unit on both in the axial direction

opposite end regions connected to one another cohesively, in particular by means of welds. The length of the valve unit and the length of the receiving device in the axial direction thus correspond to the distance between the two said welds in the opposite end regions.

Preferably, the valve unit has at least two components, which are arranged adjacent to each other in the axial direction. Said at least two components are in particular an injection valve and a connecting pipe connected thereto for supplying the reducing agent to the injection valve. The connecting pipe is preferably connected in a material-locking manner to the injection valve, in particular welded.

Furthermore, the receiving device has at least two components, which are arranged adjacent to each other in the axial direction. The said at least two components are preferably connected to one another in a material-locking manner, in particular welded. A metering device according to the invention is advantageously used in a motor vehicle which has an internal combustion engine, in particular a diesel engine, with an exhaust pipe.

Advantages of the invention

Due to the fact that the receiving device and the valve unit expand almost equally in the axial direction at the expected operating temperatures due to thermal expansion, no or only slight mechanical stresses occur within the metering device. Due to different and changing operating temperatures slightly different dimensions of the receiving device and the valve unit can not be completely ruled out. The relatively low mechanical

Tensions that result from the slightly different dimensions of the receiving device and the valve unit can be compensated by elastic deformation of the receiving device and the valve unit.

The inventive design of the metering device in particular no additional compensation element for compensating different expansions of the receiving device and the valve unit is required. As a result, the production of the metering device according to the invention compared to a known from the prior art metering device is simplified and cheaper.

Brief description of the drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below.

Show it:

Figure 1 shows a cross section through a metering device and FIG. 2 shows a simplified substitute representation of that shown in FIG

Dosing.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is dispensed with in individual cases. The figures illustrate the subject matter of the invention only schematically.

FIG. 1 shows a cross section through a metering device 10 for introducing a reducing agent into an exhaust pipe 12 of an internal combustion engine. The metering device 10 is attached to the exhaust pipe 12 and includes a valve unit 80 and a receiving device 50 for receiving the

Valve unit 80.

The valve unit 80 and the receiver 50 extend along the axis X, which is approximately perpendicular to a central axis of the exhaust pipe 12. The valve unit 80 and the receiving device 50 are formed approximately rotationally symmetrical to the axis X, wherein the

Receiving device 50, the valve unit 80 in the radial direction approximately concentric encloses. The receiving device 50 comprises a first plate 16, a second plate 17 and a lid member 48. The lid member 48 is defined by a first

Weld seam 49 sealingly connected to the first sheet 16. The first plate 16 is sealingly connected by a second weld 56 with the second plate 17. The second plate 17 is fixed to the exhaust pipe 12.

The valve unit 80 comprises an injection valve 22 via which the

Reducing agent is introduced into the exhaust pipe 12. Furthermore, the valve unit 80 comprises a connecting tube 82, which is connected by means of a third weld 84 to the injection valve 22, and which serves to supply the reducing agent to the injection valve 22. In a first end region, which is located at a distance from the exhaust pipe 12, the cover element 48 is sealingly connected to the connecting pipe 82 by means of a first welded connection 61. In a second end region, which is located opposite the exhaust pipe 12 and opposite the first end region, the second metal sheet 17 is sealingly connected to the injection valve 22 by means of a second welded joint 62.

For radial positioning of the injection valve 22 in the receiving device 50, a holding element 66 is provided, which in a between the

Injector 22 and the receiving device 50 formed radial sleeve space 68 is provided.

Exhaust gas flowing through the exhaust pipe 12 may be relatively high

Reach temperatures. Accordingly, the exhaust pipe 12 is heated, whereby the valve unit 80 and the receiving device 50 are heated. Accordingly, a cooling device is provided which a

Damage to the metering device 10 prevented. The cooling device is integrated in the receiving device 50.

The interconnected plates 16, 17, define an annular chamber 20, which can be acted upon via a cooling medium inlet 34 and a cooling medium drain 36 with a cooling medium. As a cooling medium, a liquid, such as water, cooling water, fuel or the

Reducing agents are used. Furthermore, separating elements 58 are provided, which further divide the annular chamber 20, the individual regions of the annular chamber 20 formed thereby being in fluidic contact with one another via openings 60 provided on the separating elements 58. In this way, the cooling medium is given a flow path, which allows optimized cooling.

On the cover member 48, a passage 72 is provided for a control cable 74. The control cable 74 penetrates the passage 72 and is connected to the injection valve 22. FIG. 2 shows a simplified substitute representation of the dosing device 10 shown in FIG. 1. In the following, the cover element 48 is referred to as the first component B1. The first sheet 16 is referred to as the second component B2, and the second sheet 17 is referred to as the third component B3. The connecting pipe 82 is referred to as the fourth component B4, and the injection valve 22 is referred to as the fifth component B5.

The first component Bl, the second component B2 and the third component B3 extend along the axis X in the axial direction and form the receiving device 50. The first component Bl, the second component B2 and the third component B3 are arranged adjacent to each other in the axial direction. In this case, the first component Bl and the second component B2 are connected to one another by means of the first weld seam 49, and the second component B2 and the third component B3 are connected to one another by means of the second weld seam 56.

The fourth component B4 and the fifth component B5 extend along the axis X in the axial direction and form the valve unit 80. The fourth component B4 and the fifth component B5 are arranged adjacent to each other in the axial direction. In this case, the fourth component B4 and the fifth component B5 are connected to one another by means of the third weld seam 84.

The first component Bl is connected to the fourth component B4 by means of the first welded connection 61, and the third component B3 is connected by means of the second component

Welded joint 62 connected to the fifth component B5. Thus, the valve unit 80 and the receiver 50 are in the axial direction

connected to each other opposite end portions.

At a rest temperature TR of the present 20 ° C, the first component Bl has a first length LI, the second component B2 has a second length L2, the third component B3 has a third length L3, the fourth component B4 has a fourth length L4, and the fifth component B5 has a fifth length L5. At the rest temperature TR, the length of the receiving device 50 is equal to the length of the valve unit 80. Thus, it applies:

LI + L2 + L3 = L4 + L5 When the valve unit 80 is heated to a valve temperature T80 that is greater than the quiescent temperature TR, the components B4, B5 expand in the axial direction. When the pickup device 50 is heated to a pickup temperature T50, which is greater than the rest temperature TR, the components B1, B2, B3 expand in the axial direction. This will stretch the

Receiving device 50 and the valve unit 80 due to thermal expansion in the axial direction.

Here, the first component Bl undergoes a first change in length AL1, which depends on a first thermal expansion coefficient AI of the first component Bl and a first temperature difference ΔΤ1, the second component B2 undergoes a second change in length AL2, which of a second

Thermal expansion coefficient A2 of the second component B2 and a second temperature difference ΔΤ2 depends, the third component B3 undergoes a third

Length change AL3, which depends on a third thermal expansion coefficient A3 of the third component B3 and a third temperature difference ΔΤ3, the fourth component B4 undergoes a fourth change in length AL4, which depends on a fourth coefficient of thermal expansion A4 of the fourth component B4 and a fourth temperature difference ΔΤ4, and the fifth Component B5 undergoes a fifth change in length AL5, which of a fifth

Thermal expansion coefficient A5 of the fifth component B5 and a fifth temperature difference ΔΤ5 depends. The temperature differences ΔΤ1, ΔΤ2, ΔΤ3 correspond to the differences of the recording temperature T50 of the components B1, B2, B3 and the quiescent temperature TR. The temperature differences ΔΤ4, ΔΤ5 correspond to the differences of the valve temperature T80 of the components B4, B5 and the quiescent temperature TR. It applies here:

AL1 = A1 * L1 * ΔΤ1

AL2 = A2 * L2 * ΔΤ2

AL3 = A3 * L3 * ΔΤ3

AL4 = A4 * L4 * ΔΤ4

AL5 = A5 * L5 * ΔΤ5

For the difference D of the change in length of the valve unit 80 in the axial direction and the change in length of the receiving device 50 in the axial direction due to thermal expansion at the valve temperature T80 and the Receiving temperature T50, which are greater than the rest temperature TR, then applies:

D = I (AL4 + AL5) - (AL1 + AL2 + AL3) |

The quotient of the difference D of the change in length of the valve unit 80 and the change in length of the receiving device 50 in the axial direction due to thermal expansion at the valve temperature T80 and the

Receiving temperature T50 and the length of the valve unit 80 at

Quiescent temperature TR is called the ratio value V. The following applies:

V = D / (L4 + L5)

By a suitable choice of the materials of the components B1, B2, B3, B4, B5, which in each case have a thermal expansion coefficient AI, A2, A3, A4, A5, and lengths LI, L2, L3, L4, L5 in the axial direction, the said difference D as well as said ratio value V at expected valve temperature T80 and expected intake temperature T50 are minimized. In particular, given a suitable choice of materials and lengths LI, L2, L3, L4, L5 of the components B1, B2, B3, B4, B5, the ratio value V reaches at most a predefinable maximum ratio value (Vmax).

The following are some examples:

This results in D = 0 and V = 0.

Example 2: Component Material HeatLength TemperatureLength expansion difference coefficient

A [10 7K] L [mm] ΔΤ [K] AL [μηη]

Bl Invar 1 20 100 2

B2 Austenitic steel 16 20 100 32

B3 Austenitic steel 16 20 100 32

B4 Ferritic Steel 11 30 100 33

B5 ferritic steel 11 30 100 33

Here, D = 0 and V = 0. Example 3:

Component Material HeatLength TemperatureLength expansion difference coefficient

A [10 7K] L [mm] ΔΤ [K] AL [μηη]

Bl Invar 11 9 80 0.72

B2 Austenitic steel 16 31 80 39.68

B3 Austenitic steel 16 20 80 25,6

B4 Ferritic Steel 11 30 100 33

B5 ferritic steel 11 30 100 33

This results in D = 0 and V = 0.

In the examples given here, a uniform heating of the components B4, B5 of the valve unit 80 is assumed to be based on the valve temperature T80, which is greater than the quiescent temperature TR. Similarly, in the examples listed here simplifying of a uniform heating of the components B1, B2, B3 of the receiving device 50 on the

Receiving temperature T50 is assumed, which is greater than the idle temperature TR.

During operation of the metering device 10, however, the components B4, B5 of the valve unit 80 can also assume different temperatures. Likewise, during operation of the metering device 10, the components B1, B2, B3 of the

Receiving device 50 different temperatures. Furthermore, it is conceivable that partial regions of the individual components B1, B2, B3, B4, B5 have different temperatures. Such inhomogeneous temperature distributions in the valve unit 80 and in the receiving device 50 should also be taken into account in the design of the metering device 10. Furthermore, valve temperatures T80 and recording temperatures T50, which are smaller than the assumed rest temperature TR, should be taken into account.

The invention is not limited to the described embodiments and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of professional practice.

Claims

claims

1. metering device (10) for introducing a reducing agent into an exhaust pipe (12) of an internal combustion engine, comprising a valve unit (80) and

a receiving device (50) for receiving the valve unit (80), wherein

the receiving device (50) and the valve unit (80) extend along an axis (X) in the axial direction, and wherein

at a quiescent temperature (TR)

a length of the receiving device (50) in the axial direction

at least approximately the same

is a length of the valve unit (80) in the axial direction,

characterized in that

the receiving device (50) and the valve unit (80) are designed in such a way that

the difference (D)

a change in length of the valve unit (80) in the axial direction due to thermal expansion at a valve temperature (T80) and

a change in length of the receiving device (50) in the axial direction due to thermal expansion at a receiving temperature (T50) reached at most a maximum ratio (Vmax) relative to the length of the valve unit (80) at rest temperature (TR).

2. dosing device (10) according to claim 1, characterized in that the valve temperature (T80) in a range of 60 K below and 200th

K is above the quiescent temperature (TR), and that

the recording temperature (T50) is in a range of 60 K below and 200 K above the quiescent temperature (TR), and that

a temperature difference between the valve temperature (T80) and the absorption temperature (T50) is a maximum of 100 K. Dosing device (10) according to one of the preceding claims, characterized in that

the maximum ratio value (Vmax) is less than 2% ₀ .

Dosing device (10) according to one of the preceding claims, characterized in that

the valve unit (80) is formed at least approximately rotationally symmetrical to the axis (X).

the receiving device (50) at least approximately

is formed rotationally symmetrical to the axis (X).

the receiving device (50) surrounds the valve unit (80) in the radial direction.

the receiving device (50) and the valve unit (80) are connected to one another in a material-locking manner at both end regions lying in the axial direction, in particular by means of

Welded joints (61, 62).

the valve unit (80) has at least two components (22, 82) which are arranged adjacent one another in the axial direction.

the receiving device (50) has at least two components (16, 17, 48),

which are arranged adjacent to each other in the axial direction. Use of a metering device (10) according to one of the preceding claims in a motor vehicle having an internal combustion engine.