WO2012171757A1

WO2012171757A1 - Conveyor assembly for operating/auxiliary materials for internal combustion engines

Info

Publication number: WO2012171757A1
Application number: PCT/EP2012/059489
Authority: WO
Inventors: Rainer Haeberer
Original assignee: Robert Bosch Gmbh
Priority date: 2011-06-16
Filing date: 2012-05-22
Publication date: 2012-12-20
Also published as: DE102011077617A1

Abstract

The invention relates to a conveyor assembly (10) for conveying an operating/auxiliary material, in particular a reducing agent, for penetrating an exhaust gas tank of an internal combustion engine, comprising a magnet unit (12), which comprises a solenoid (18) and a pump housing (24), which has channels (26, 28, 30) and conveyor elements (34, 36, 38) for the operating/auxiliary material. The components (4, 16, 18, 20 and 22) of the magnet unit (12) are arranged separately in the conveyor assembly (10) in relation to the components (24, 26, 30, 32, 34), which are in contact with the operating/auxiliary material.

Description

Description title

State of the art In the case of internal combustion engines for motor vehicles or hybrid vehicles, due to the stricter exhaust gas legislation (Euro 6) pending in the next few years, the pollutant NO _x contained in the exhaust gas of self-igniting internal combustion engines is to be reduced. A suitable method is the SCR method (SCR = selective catalytic reduction) with which the pollutant NO _x with the aid of a liquid operating or operating / auxiliary substance, in particular a reducing agent such as urea or a urea-water solution, to N ₂ and H ₂ 0 is reduced. The operating / auxiliary substance is usually from a arranged close to a tank for storing the operating / auxiliary feed pump in a line from this storage tank to a

Dosing module promoted. The metering module has an active, electric valve via which the amount of reducing agent is introduced into the exhaust tract of the self-igniting internal combustion engine when actuated.

EP 1 555 433 A2 relates to a metering pump system and a method for

Operating a dosing pump. The metering pump system comprises a metering pump with at least one metering pump element movable between two movement end positions and one associated with the at least one metering pump element

Dosing pump element drive. The metering pump element drive comprises a

Coil arrangement and a drive device. This serves to move the at least one metering pump element in at least one direction of movement. The

Coil arrangement generates a magnetic force interaction, wherein the drive device is designed to operate the coil assembly at least in phases pulsed during a, corresponding to a Dosierpumpenelementen- movement process drive interval. EP 1 878 129 A1 likewise shows a metering pump. This serves to convey a liquid, wherein the pump has an input and an output and a pumping chamber. In the pumping chamber the medium is taken up from the inlet. By means of an actuating arrangement which can be actuated between a first and a second position, the fluid is conveyed from the pumping chamber in the direction of the outlet. The inlet of the pumping chamber is in fluid communication with a supply channel when the

Actuator assembly is located in the first position. The supply channel extends around the actuator assembly so that heat can be absorbed by the actuator assembly through the medium to be conveyed, and thus cooled.

US 5,509,792 relates to an electromagnetically driven conveyor with piston. The piston is operated by means of alternatively energizable coils.

In a cooling of the actuator assembly by the medium to be delivered in the case of promotion of a reducing agent, such as AdBlue parts of

Actuating arrangement with the reducing agent, for example via a flooded anchor space, directly in contact. The reducing agent, in particular AdBlue, has the negative property of developing very aggressive properties with regard to plastic and metals at high temperatures as a result of the formation of free ammonia. One

Spool carrier, which is sealed to a housing via elastomer rings, is in direct contact with the aggressive properties AdBlue. This in turn means that heated reducing agent will damage the winding support, which is generally made of plastic, and eventually the Cu coil by ammonia diffusion. In the past occurred damage, such. As damage by NH ₃ diffusion, injected in elastomer Cu wires by NH ₃ , are due to this effect. Furthermore, the previously desired, generally inexpensive and manufacturing technology very easy to assemble, used elastomeric rings in a reducing agent environment at elevated temperature level brittle and therefore be leaking. To avoid these disadvantages and to prevent corrosion, therefore, the armature, yoke and housing of an electrically actuated valve made of a high-quality stainless steel to manufacture. However, the use of a high quality stainless steel has the disadvantage that it has poor magnetic properties and thus the magnet and the coil by corresponding larger current and larger Must compensate for number of turns. This in turn is accompanied by an increased thermal load.

In alternative solutions, anchor yoke and housing are used to protect against

Reductant galvanically chromium plated. Thus, according to this embodiment possibility also a magnetically active substance can be used. The winding support is sealed by a stainless steel sleeve, which is welded to the yoke and the housing. Since welding of chrome-plated parts is not possible, the chrome would have to be removed beforehand at the weld, whereby the material would be attacked by the reducing agent at such a prepared weld again. Therefore, this path does not seem feasible.

DESCRIPTION OF THE INVENTION According to the invention, a delivery unit is proposed whose individual components, such as, for example, its actuating magnet, its pumping element and its armature, including the cover, have a modular construction. This makes it possible to interpret each of the components of the delivery unit proposed according to the invention independently of each other and to tune in an optimal manner to the respective operating requirements. Thus, advantageously, the parts in contact with the operating / auxiliary material are not involved in the formation of the magnetic forces. These parts, which come into contact with the operating / auxiliary substance, in particular reducing agents such as, for example, urea or a urea-water solution, can therefore be designed with regard to their requirements for the corrosion of optimal materials and do not inevitably need to

To meet compromises leading requirements, as required for example in the magnetic circuit.

In a further advantageous embodiment of the idea underlying the invention, these materials have a coefficient of conduction which is better by a factor of 3, which thus better dissipates the heat arising during operation of the delivery unit proposed according to the invention from the actuating coil into the pump housing. The

Pump housing, which comes into contact with the operating / auxiliary material, in particular the reducing agent, is made of a corrosion-resistant material, which is inferior in terms of its heat conduction. In this case, however, a poorer heat conduction of the material of the pump housing can be accepted as the Pump housing is only a heat sink and main focus is placed on the cooling of the actuator coil.

The delivery unit proposed according to the invention comprises a pump housing which is essentially cylindrical and has a very large areal connection to a yoke of the magnetic circuit. As a result, the waste heat generated during operation of the coil can be released very well to the pump housing cooled by the reducing agent, in particular by the operating / auxiliary substance. The cylindrically shaped pump housing comprises a supply line for the operating / auxiliary material and a pressure-side outlet, which leads to the injection valve for the operating / auxiliary material in the exhaust gas tract of the internal combustion engine.

In the pump housing is located in the upper part of a pump element, for example designed as a piston, which is fitted into a cylinder with a slight play of a few μηη. By means of the piston, a suction valve, for example, designed as

Slit valve opened or closed. If the movable piston exceeds a suction opening coming from bottom dead center, pressure builds up. Despite tight guidance between piston and cylinder, a small amount of leakage can occur during pressure build-up, but this is sealed off by an elastomeric seal. Between the elastomeric seal and the cylinder creates a space, which via a hydraulic connection with a

Supply line for the reducing agent is in communication. Due to the adjusting piston stroke of the operating / auxiliary substance contained in this space, in particular the reducing agent, always renewed and thus can not age and develop harmful properties. To accommodate the stroke, the elastomeric seal used is formed in a deformation enabling ripple.

The elastomeric seal of the room faces away from the magnetic coil representing the heat source and is cooled by the operating / auxiliary material as it is being conveyed. Furthermore, it is ensured due to the proposed solution according to the invention that the critical components in terms of their durability anchor and return spring not with the corrosive aggressiveness developing on operating / auxiliary material in

Get in touch. In an advantageous manner and for the reduction of the actuating forces, the armature may be provided with at least one recess in the region not of magnetic interest for weight saving. To ensure the Eisdruckfestigkeit is a cover element of the delivery unit with elasticity, such as by Shaft design provided so that an optionally building ice pressure can be absorbed in the axial direction. Furthermore, the elasticity of the lid is advantageous in terms of reducing end stop noise. However, these are low per se, since the spring, which serves the provision of the anchor, in the end stop has only a small force of about 10 Newton and the piston is damped in his leadership. Furthermore, when the piston is stopped in the cylinder bottom, ie the top dead center, the noise is hydraulically damped by the cylinder filled with fluid.

With regard to the ice crushing strength of the delivery unit proposed according to the invention this promotion is taken into account that small volumes, eg. B. that of

Operating / auxiliary receiving space are provided; on the other hand appropriate compensation options such. As an outwardly opening injection valve, a lid with an upper portion and a resilient properties elastomeric seal, which may also be performed wavy, are used. Furthermore, the sealing points on the pump housing are limited to two sealing points. A first sealing takes place via said elastomeric seal during cooling in a lower temperature suction region and via a high-pressure seal via a proven seal outside the magnetic coils. This seal is in the outer area. Short description of the drawing

With reference to the drawing, the invention will be described below in more detail.

The single FIGURE shows a section through the inventively proposed

Delivery unit for the promotion of an operating / auxiliary material for internal combustion engines, in particular a reducing agent.

Embodiments The illustration of Figure 1 is an embodiment of the present invention proposed delivery unit for promoting an operating / auxiliary material, in particular a reducing agent for exhaust aftertreatment, such. As urea or a urea-water solution. A delivery unit 10 comprises a magnet assembly 12, which comprises a magnet yoke 14, a magnet coil 18 and an armature 20. The components of the magnet assembly 12 are also located in a housing 16 as the components that are in direct contact with the by the delivery unit 10 to be conveyed operating / auxiliary materials, in particular a reducing agent. These components are also included in the above

Substantially enumerated components of the magnetic group 12 are arranged separately. This means that the components of the magnet assembly 12 do not come into direct contact with the operating / auxiliary substance to be delivered, in particular a reducing agent. From the illustration according to FIG. 1, it can be seen that the housing 16 is closed by a cover 22. The cover 22 substantially encloses the armature 20 of the above-mentioned magnet assembly 12. In the housing 16, a pump housing 24 is embedded. This is surrounded by the magnetic yoke 14 of the magnet assembly 12 substantially over a large area, so that a good heat-conducting connection of the magnetic yoke 14 is given to the pump housing 24. The surface connection of the pump housing 24 to the magnetic yoke 14 can be realized either via the formation of a slight press fit or the representation of a long threaded portion. The large-area connection of the pump housing 24 to the magnetic yoke 14 causes the heat generated in the magnetic coil 18 of the magnetic assembly 12 can be very well delivered to the pump housing 24 cooled by the to be funded operating / auxiliary material, or the reducing agent. In the pump housing 24 there are a supply line 26 for the operating / auxiliary material, in particular a reducing agent, and a pressure-side outlet 28, which extends to a valve 86, which is indicated here only schematically. The pump housing 24, the surface of the magnetic yoke 14 of the magnet assembly 12th

is further connected, further comprises a radially arranged connection 30, which is a

Ball or a cube may include. These components can be over

Clamping element 32 are clamped in the radial direction. In the upper area of the

Pump housing 24 is a pump element 34, which may be in particular a piston, which is pressed in a cylinder 36 with a slight clearance of a few μηη and immersed into the cylinder 36 until it stops. An upper dead center of the piston-shaped pump element 34 is defined by the stop on the cylinder bottom 76 of the cylinder 36. As Figure 1 further shows, in the pump housing 24, a suction valve in the form of a slit valve 38 is executed. The piston-shaped pump element 34 coming from its bottom dead center, opens a bore of the slit valve 38, a pressure build-up begins. The bottom dead center of the Pump element 34, which uses a pressure build-up is, by a

Locking screw 70 is set. In this case, a residual air gap 60 is set according to the specifications. FIG. 1 further shows that on the pressure side of the cylinder 36 a valve,

in particular designed as a check valve 80, is arranged. The check valve 80 comprises a formed with a biasing element valve closure member 84, which opens at queuing a corresponding back pressure in a pressure chamber 82, so that the operating / auxiliary material via the pressure-side outlet 28 in the lower part of the

Representation according to Figure 1 disposed valve 86 can flow. That as

Check valve 80 formed valve is preferably pressed into the pump housing 24. Despite a tight guide between the piston-shaped

Pump element 34 in the cylinder 36, occurs at pressure build-up leakage, which has a

Elastomerabdichtung 40, which may be formed vulcanized, for example, to a coupling piece 42 is sealed. This is a transfer of the higher

Temperatures aggressive properties exhibiting operating / auxiliary substance or a contact thereof with the components of the magnet assembly 12 prevented. In a storage space 48, this leakage is collected, wherein the discharge of the storage space 48 via a hydraulic connection 50 in the supply line 26 for the operating / auxiliary substance takes place. Due to the stroke of the piston-shaped pump element 34 collected in the storage space 48 operating / auxiliary material, in particular a reducing agent, always renewed, so that its aging and thus its harmful effects

are largely neutralized. The elastomeric seal 40 is formed in a ripple for receiving a stroke that is a few millimeters. At the outer edge there is a bead 52, which is embedded in a groove in cylinder 36 and is pressed over a pulley 54 in this. By means of a flange 56, for example, which is formed on the pump housing 24, in particular on its upper edge, the disk 54 can be held permanently in its position while maintaining the clamping action for the bead 52.

Since the storage space 48 is located on the suction side, this is relieved. This means that the storage space 48 is tight. The seal is located on the of the

Heat source, ie the magnet assembly 12, side facing away, with a cooling via the operating / auxiliary substance itself. As is further apparent from FIG. 1, the coupling piece 42 comprises on both sides respective pins 44, 46, which are both designed as threaded pins could be. On the lower side of the coupling piece 42, ie on the second threaded pin 46, the piston-shaped pump element 34 is clamped, on the upper side, ie on the first threaded pin 44, the attachment of the armature 20. The adjustment of a residual air gap 60 via an inserted disc 58th In the illustration according to FIG. 1, the residual air gap 60 is indicated by an arrow which extends between the upper planar surface of the magnet yoke 14 on the one hand and the underside of the armature 20 of the magnet assembly 12 on the other hand. The return spring 62 is supported on the underside of the armature 20 on the one hand and on the top of a flat surface of the magnetic yoke 14 on the other hand.

From the selected structure of the delivery unit 10, it follows that the critical components armature 20 and critical in terms of their durability return spring 62 does not come into contact with the conveying unit 10 to be conveyed operating / auxiliary material, in particular a aggressive at higher temperatures developing reducing agent , The armature 20 is as further apparent from the illustration of Figure 1, provided in the magnetically uninteresting region for weight saving with at least one recess 64. The cover 22 is part of the magnet assembly 12 and closes the magnetic circuit to the armature 20 via a radial air gap 66. To avoid excessive lateral forces is to strive to form the radial air gap 66 about 0.5 mm wide. The lateral force is proportional to 1 / r ² , so that with increasing radial air gap 66, the lateral force decreases. To ensure compensation, the axial height of the

Radial air gap 66 be as large as possible, so the anchor 20 is pulled up again flat on its outside, d. H. extends in its outer region parallel to the inside of the magnet assembly 12 occlusive cover 22. The lid 22, which closes the magnet assembly 12, has in its upper portion 72 a setting for the magnet hub in the form of a shim 68, and a screw plug 70. The lid 22 may have in its upper portion 72 further elastic properties, for example, by a wavy design of the upper portion 72 are given. As a result, z. B. be ensured in an advantageous manner that a building up ice pressure can be absorbed in the axial direction. Furthermore, elasticity in the mentioned range is advantageous for reducing

End stop sounds that may result upon actuation of the armature 20 of the magnet assembly 12. The end stop sounds, however, will remain low as the

Return spring 62, which acts on the movable armature 20 formed in the end stop only a spring force of a few Newtons and the movable, piston-shaped pump element 34, is damped in the cylinder 36 by guiding in this.

In the inventive proposed delivery unit 10, in which the components of the magnet assembly 12 do not come in contact with the aggressive at higher temperatures developing operating / auxiliary material, the problem of ice crushing strength advantageously by small volumes, such. B. a small volume of the storage space 48, and on the other hand by appropriate

Compensation options, such. B. an outwardly opening injection valve 86, and a lid 22 which has elastic properties in the upper region 72, as well as by elastic properties having elastomeric seal 40 to the storage space 48 solved. The sealing points on the pump housing 24 are limited to two, with a seal over the resilient elastomeric seal 40 is formed which is formed in the lower temperature level suction region and a high pressure seal on the radial connection 30 on the other hand, which represents a proven seal outside the Magnet assembly 12 is located. This sealing point is located in the outer region, so that in case of the occurrence of small leaks, the delivery unit 10 is not affected. In an advantageous manner, according to the invention, the proposed design of the delivery unit 10, the components of the magnet assembly 12, d. H. Anchor 20,

Magnetic yoke 14, housing 16 and cover 20, since they do not come into contact with the operating / auxiliary material, are made of magnetically high-grade steel, which favors their correspondingly smaller dimensions in an advantageous manner.

In the pump housing 24, which directly in contact with the operating / auxiliary material, in particular a at higher temperature level aggressive properties

developing reducing agent is, there are the supply line 26, the slit valve 38, and a pressure-side outlet 28th

In a particularly advantageous manner, the operating / auxiliary material, in particular the

Reducing agent leading parts are not involved in the formation of magnetic forces. The structure of the magnetic forces takes place exclusively by components within the magnet assembly 12, which do not come into contact with the operating / auxiliary material, in particular a reducing agent having aggressive properties. This allows the components of the Magnetic circuit 12 are filled with magnetically suitable materials and optimized and passing with the operating / excipient in contact components of the

Conveyor units 10 are made of resistant and resistant materials because they are not part of the magnet assembly. The components installed in the magnet assembly 12 are made of materials having magnetically active properties and, moreover, have an approximately factor 3 better coefficient of thermal conduction, so that a better transfer of the heat, in particular from the magnet coil 18 to the magnet yoke 14, into the pump housing 24 , which in turn is cooled by the operating / excipient is ensured. The pump housing 24 itself is made of an operating / excipient-resistant material, but is inferior in terms of its heat conduction. Thus, the components of the magnet assembly 12, pump element 34, armature 20 and cover 22, can be designed independently of each other and each optimally adapted to the requirements, without having to compromise on other functional areas.

Claims

claims

1 . Delivery unit (10) for the promotion of an operating / auxiliary substance, in particular a

Reducing agent, for entering an exhaust tract of a

Internal combustion engine, comprising a magnet assembly (12) comprising a solenoid (18) and a pump housing (24) having channels (26, 28, 30) and

Includes conveying elements (34, 36, 38) for the operating / auxiliary substance, characterized

characterized in that components (14, 16, 18, 20 and 22) of the magnet assembly (12) are separated in the delivery assembly with respect to components (24, 26, 30, 32, 34) in contact with the operating / auxiliary material (10) are arranged.

2. delivery unit (10), according to claim 1, characterized in that the

Pump housing (24) the operating / excipient leading lines (26, 28, 30).

3. delivery unit (10) according to one of the preceding claims, characterized

characterized in that the pump housing (24) to one of the components,

in particular a magnetic yoke (14) of the magnet assembly (12) is connected flat.

4. delivery unit (10) according to the preceding claim, characterized in that the surface connection by a slight press fit or by a

Thread portion is shown.

5. delivery unit (10), according to one of the preceding claims, characterized

characterized in that the pump housing (24) comprises a pump element (24), which is designed piston-shaped and a storage space (48) which is sealed by an elastomeric seal (40).

6. delivery unit (10), according to the preceding claim, characterized in that the elastomeric seal (40) with a possible their deflection

Profiling, in particular in a waviness, is provided.

7. delivery unit (10) according to one of the preceding claims, characterized

characterized in that the components (14, 18, 20) of the magnet assembly (12) are made of a material having a coefficient of thermal conductivity greater than 3 Coefficient of thermal conductivity of the material which is in contact with the operating / auxiliary materials.

8. delivery unit (10), according to one of the preceding claims, characterized

in that at least the pump housing (24) is made of a material resistant to the operating / auxiliary material.

9. delivery unit (10) according to one of the preceding claims, characterized

in that the components (14, 18, 20) of the magnet assembly (12) are made of magnetically high-grade material, in particular a magnetically high-grade steel.

10. delivery unit (10) according to one of the preceding claims, characterized

characterized in that the particular of the magnetic yoke (14) of the

Magnetic assembly (12) enclosed pump housing (24) through which the channels (26, 28, 30) flowing through the reducing agent is cooled.