WO2012065777A1

WO2012065777A1 - Valve having a housing made of plastics material

Info

Publication number: WO2012065777A1
Application number: PCT/EP2011/066438
Authority: WO
Inventors: Markus Ulrich; Christoph Waletzek
Original assignee: Robert Bosch Gmbh
Priority date: 2010-11-18
Filing date: 2011-09-21
Publication date: 2012-05-24
Also published as: DE102010044090A1

Abstract

The invention relates to a valve (48) of a delivery system of a motor vehicle, wherein an actuator (68) is movable between a first valve position and a second valve position. By virtue of a bonded connection, the plastics housing (74, 72) of the valve (48) is fluid-tight and able to withstand high mechanical stress.

Description

description

title

Valve with a housing made of plastic The invention relates to a valve according to the preamble of claim 1.

State of the art

Such a valve is used for example as a 4/2 way valve in a conveyor system for a liquid reducing agent. The conveyor system serves to

It is necessary to inject liquid reducing agent into the exhaust gas line of an internal combustion engine of the motor vehicle in order to stimulate a catalytic reduction of nitrogen oxides in an SCR catalytic converter (SCR = SCR). The liquid reducing agent may be, for example, a urea-water solution.

From DE 20 2007 018 318 U1 a 4/2-way valve is known in which an actuator actuates an actuator of the valve. The actuator can reciprocate the actuator between two switch positions. The actuator has approximately longitudinally in the longitudinal direction on a bearing about which the actuator is rotatable or tiltable. In each of the two valve positions is a

Line released for transporting a liquid. The closing of the respective other line is arranged by a arranged on the actuator

Realized sealing element, which cooperates with a valve seat. The pressing force is transmitted from the actuator via the actuator to the sealing element.

From WO 2005/108840 A1, a further directional control valve is known, which comprises two housing parts bolted together. Between the housing parts, an actuator is sealingly clamped. This actuator has a metallic core, which is encapsulated with an elastic plastic. In this case, a circular sealing ring is formed. In addition, on the actuator Formed sealing surfaces which cooperate with the arranged in the housing parts sealing seats.

Since the housing parts are bolted together, is an additional

Sealing between the housing parts required. Furthermore, the

Space requirement of this valve is relatively high, which when used in the

Automotive technology is disadvantageous.

Disclosure of the invention

The valve according to the invention has a bottom plate and a valve cover made of plastic, which are connected to one another in the region of a joining surface cohesively. Through the use of plastic, preferably one

thermoplastic material, it is possible to realize the functions "connect" and "seal" by a material-locking connection.This reduces the manufacturing costs and simplifies assembly, malfunctions, for example, by inlaid seals and the like more can be safely ruled out Production of the cohesive connection between the valve cover and base plate according to the invention can be automated very well, so that a fully automatic assembly of the valve according to the invention is possible.

In an advantageous embodiment of the invention, the first joining surface is formed by a circumferential rib and a complementary to the rib-shaped counter surface, wherein the rib and the counter surface before they are materially connected to each other by a non-positive interference fit with each other. As a result, the components to be joined are positioned and fixed relative to one another without additional aids. It is then possible, for example, through the valve cover and the bottom plate

Laser welding, electron beam welding or ultrasonic welding to join together materially. Due in the field of

Joining surface prevailing press fit ensures an intimate connection of the two joining partners and it is also ensured that after joining a mechanically highly resilient and liquid-tight connection between the base plate and the valve cover is present. The production of this Connection is very easy to automate, which is beneficial to the

Production costs affects.

The valve according to the invention can also be materially connected to one another in the region of a second joining surface with the housing part of an actuator which actuates the valve. In this case, in a similar manner, in the region of a second joining surface, a press fit is produced before the

cohesive connection is made. As a result, the advantages mentioned above in connection with the first joining surface are also realized for the connection between the housing part and the valve.

In order to be able to realize a particularly compact design, liquid channels are formed in the housing part through which - depending on the switching position of the valve - urea-water solution or another liquid medium flows.

In order that no liquid from the inside of the valve or the housing part can escape to the outside, is in the region of a third joining surface between the

Valve cover and the housing part a seal, preferably made of a thermosetting two-component sealant provided. This thermosetting two-component sealant may be prior to joining the valve to the

Housing part are introduced into a correspondingly prepared groove of the valve cover. Subsequently, as long as the hardening sealant is still malleable, the valve and the housing part are positively connected to each other and then welded. In this position then cures the sealant and the desired seal is made. Alternatively, it is also possible to weld the components together liquid-tight.

In a further advantageous embodiment of the invention, the actuator

partially covered with plastic, wherein a valve cover and a bottom plate of the valve surround the plastic jacket in the interior of the valve and fix, that the actuator between the first and the second valve position is movable.

The plastic sheath of the actuator forms the bearing for the actuator and seals the valve to the outside. The plastic casing according to the invention is clamped between the valve cover and the bottom plate and leaves by their deformability, the necessary adjusting movement of the actuator between the first and second switching position. The plastic sheath is designed so that it out of the

Switching movements of the actuator resulting deformation over the life of the valve withstands. It is according to the invention also possible to exert a spring force on the actuator by the elastic plastic, wherein the movement of the actuator is realized substantially by a movable between two switching positions armature of the actuator.

The anchor is arranged in an actuating part, wherein the

Actuator is coupled to the valve. The armature movement can also be supported by spring elements.

In the valve according to the invention, the actuator is designed as a fork-shaped lever, wherein the free ends of the fork two substantially

Having oppositely disposed sealing surfaces. Close the sealing surfaces, or open the associated channels of the valve.

The main body of the fork-shaped actuator is a metal part to which, for example, an elastomer such as ethylene-propylene-diene rubber (EPDM) is vulcanized. Previously, a bonding agent can be applied to create a permanent connection. Elastomers are, for example, for use in an SCR system, urea resistant and also sufficiently dimensionally stable, but still elastically deformable. In addition, elastomers can deform elastically under tensile and compressive load and then return to their original, undeformed shape. They also have good sealing properties.

In an advantageous embodiment of the invention, the sealing surfaces are arranged conically at the ends of the actuator according to the adjustment angle of the actuator. This allows the valve seats in the bottom plate and the

Valve cover of the valve without consideration of the adjustment angle of the valve

Are made actuator and still given a uniform support of the sealing surfaces on the valve seats. The valve seats at the located in the interior of the valve ends of the channels are preferably rounded and have a small contact surface, so that a high surface pressure is generated despite a small actuating force of the actuator by this shaping. This will be a high

Achieved sealing effect. The sealing effect can be further improved in this area of the valve by insertable O-rings. An internal leakage is thereby advantageously avoided.

Further, the bottom plate on its side facing away from the actuator on a recess which serves to receive a flat gasket with channel guides. The flat gasket can be inserted precisely into the recess. This prevents the flat gasket from slipping out of its intended position. The flat gasket is arranged between the bottom plate and a housing part of the actuator.

At the surfaces of the bottom plate and the housing part, which are in contact with the flat gasket, at least one bead is formed, which is the

Flat gasket elastically deformed. This elastic deformation significantly improves the sealing when the bead or beads run as closed rings or curves, for example around a channel guide in the flat gasket. For then several hydraulic connections can be passed through the gasket and a hydraulic short circuit between these compounds can be effectively prevented.

The beads have the function of a biting edge. When the valve according to the invention and the housing part are connected to each other, then the circumferential bead presses both the sealing plate and the housing part in each case from opposite sides in the flat gasket and deform them elastically. This also means that in the field of

Contact surface between the beads and the flat gasket an increased surface pressure occurs, which has a positive effect on the tightness.

It is also possible that in a sense alternately that the beads of sealing plate and housing part offset from one another, so seen in cross section, the flat gasket is mutually elastically deformed from both sides and thereby a further improved sealing effect is achieved. To ensure that despite this elastic deformation of the gasket, the distance between the housing part and valve can be kept within close tolerances, projections are formed either on the sealing plate or on the housing part, which protrude through corresponding shaped recesses of the gasket and a direct contact between the bottom plate and valve and housing part allow. As a result, an exact positioning is achieved and on the other hand, the contact pressure between the beads and the

Flat gasket limited to a specified value. This also leads to an improved sealing effect and an increased service life.

It is also advantageous that the bottom plate, the actuator and the

Valve cover when mounted in the manner of a sandwich assembly

are composable. That means on the bottom plate as

Basic body, successively the flat gasket, if necessary, O-rings, the actuator and finally the valve cover are placed on each other. There are no screw required, so the valve is very easy to

assemble is. The valve cover is designed to encapsulate the entire valve. In this way, a structural unit is created.

In addition, it is advantageous that the bottom plate in one of the

Valve cover substantially protruding and circumferential rib by a

Press fit can be used and then welded together.

According to the invention, the rib is dimensioned in such a way that a press fit is created when joining both components. This interference fit holds the components together and presses the parts against each other during melting, for example during laser welding. This creates a mechanically highly durable and liquid-tight connection. In the preferred embodiment, the actuator between a first and a second switching position in the axial direction by the armature is movable, wherein the armature is part of an actuator. The actuator is in the one coupled to the valve

Operating part arranged. The linear actuator in this case comprises an electromagnet which moves the armature designed as an armature axially. The electromagnet may comprise a profiled pin for stabilization and positioning, which in one

Receiving device of a housing of the actuating part can be locked. Further advantages will be apparent from the dependent claims, the description and the attached figures.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show, each in

schematic form:

Fig. 1 the environment of the invention;

FIG. 2 shows an illustration of a 4/2-way valve from FIG. 1 with an actuating part in a longitudinal section;

Fig. 3 is a detailed illustration of the 4/2-way valve of Figure 2 in one

Longitudinal section;

4 shows a fork-shaped actuator of Figure 2 or 3 in a plan view.

Fig. 5 is a section A - A of Figure 4;

6 shows a bottom plate from FIG. 3 with a flat gasket in detail;

7 is an exploded view of the components of the valve of Figure 3; and

8 shows a further longitudinal section through the valve from FIG. 2.

FIG. 1 shows an SCR system 10 (SCR = Selective Catalytic Reduction) in a motor vehicle with a liquid reducing agent delivery system 12, for example a urea-water solution, which is injected into an exhaust pipe 14 of an internal combustion engine as needed in order to generate a fuel catalytically reducing nitrogen oxides in an SCR catalyst 16. A not completely shown in Figure 1 Exhaust gas aftertreatment device usually comprises, in addition to the SCR catalytic converter 16, essentially also an oxidation catalytic converter, a particle filter and an oxidation catalytic converter. The flow direction of the exhaust gas through the exhaust pipe 14 is indicated by an arrow 18.

In order to supply the SCR catalyst 16 with urea-water solution, upstream of the SCR catalyst 16 at the exhaust pipe 14, an inlet pipe 20 for the urea-water solution is provided, which introduces the urea-water solution into the exhaust pipe 14. A metering of the urea-water solution takes place via a preferably electrically operated metering module 22, which is influenced by signals of a NO _x sensor 23, which is arranged downstream of the SCR catalytic converter 16. Between a heat exchanger 24 and the dosing module 22, a first line (Reduktionsmittelzuführleitung) 26 is provided. In the other direction from the heat exchanger 24 outgoing a second line 28 is arranged, which is formed to an input of an electrically operated 4/2 way valve 48. Further information about the 4/2-way valve 48 follows further back. A pressure in the second conduit 28 is monitored by a pressure sensor 32.

The conveyor system 12 also includes a storage tank 34 for the urea-water solution. The storage tank 34 has a heater 33 for heating the urea-water solution; the corresponding temperature of the urea-water solution is monitored by a temperature sensor 35. The urea-water solution is pumped by a pump 36 from the storage tank 34 via a suction line 37 and a filter 38 in a normal position of the 4/2-way valve 48 shown in Figure 1 in a third line 40. Behind the pump 36, a section 40 'of the third line opens again into another port of the 4/2-way valve 48, after which the urea-water solution of the second line 28, further the first line 26 and ultimately the metering module 22 is fed. The third conduit 40 'has a branch in a return line 42 for the urea-water solution. In the return line 42, a throttle 44 is additionally arranged.

In a second, not shown, the position of the 4/2-way valve 48, a reverse flow (sucked back) of the urea-water solution by the delivery system 12, for example, to prevent damage by freezing pressure at cryogenic temperatures and / or for venting the lines 26, Realized 28, 40 and 40 ' become. For this purpose, after a stoppage of the vehicle, the 4/2-way valve 48 is switched to the second switching position. In regular delivery mode (at normal position = first shift position), the 4/2-way valve 48 is held in the normal position by the spring force of a spring element.

Figure 2 shows an illustration of a 4/2-way valve 48 according to the invention with an actuator 46 in a longitudinal section. The actuator 46 serves to switch the two switching positions of the valve 48 and is coupled to the valve 48. The solenoid 52 is pressed by a profiled pin 54 in a frusto-conical receiving bore of the housing 56 of the actuating member 46 and is thereby fixed. An additional screw or the like is not required. This facilitates a fully automatic assembly.

The actuator 46 includes an axially movable armature 50 that is moved by a solenoid 52. The solenoid 52 can thus two positions

taking. The contacting of the lifting magnet 52 via two contacts 58 (in the longitudinal section of Figure 2, only one contact 58 is visible), which are inserted into the housing 56 and centered. The contacts 58 are injected into a magnet coil body of the solenoid 52 (see reference numeral 60). The respective switching position of the 4/2-way valve 48 is supported by the spring force of two spring elements 62 and 64 positioned around the magnet armature 50.

At the armature 50, a pivot receiver 66 is arranged for a preferably made of metal fork-shaped actuator 68. The pivot receiver 66 engages in the fork-shaped actuator 68. By moving the magnet armature 50, the fork-shaped actuator 68 can thus be pivoted (see arrow 70). The actuator 68 is used for switching the 4/2-way valve 48th

FIG. 3 shows the valve 48 in detail for a more detailed explanation. The valve 48 essentially comprises a bottom plate 72, a projecting into the valve 48 part of the

Actuator 68 and a valve cover 74. The valve cover 74 may form the largest part of a housing of the valve 48. The actuator 68 is arranged between the valve cover 74 and the bottom plate 72. Through a recess 75 between the bottom plate 72 and valve cover 74, the actuator 68 is given sufficient freedom to the tilting or rotational movement between the two Perform switching positions. The located in the valve 48 part of

fork-shaped actuator 68 is coated with an elastic plastic 76, preferably an elastomer, by the plastic was vulcanized onto the actuator 68. If necessary, an adhesion promoter can be applied before vulcanization.

During vulcanization, an annular bead 78 and at the free end (the "prongs" of the fork) two sealing surfaces 80, 81 are produced for sealing channels 84, 85 arranged in the valve 48. For this purpose, the channels 84, 85 respectively at their ends Specially designed valve seats 82, 83. Further details are given below: The annular bead 78 forms a sealing ring which prevents the medium inside the valve 48 from entering the environment, for example through the recess 75.

In addition, the valve cover 74 has a preferably formed from elastomer and circumferential around the circumference seal 87, which is also intended to prevent that located in the interior of the valve 48 medium, for example, urea-water solution, exits. Alternatively, instead of the seal 87 and a weld can be provided.

For example, to a channel 84 extending downwardly in FIG. 3, the conduit 40 'and to an upwardly extending channel 85, the conduit 40 of the

Be connected delivery system 12. To a guided through the bottom plate 72 channel 86, for example, the suction line 37 is connected. The fact that the channels are guided according to the invention by the housing part 56, a very compact design of valve 48 and actuator 46 can be achieved.

3, only one free end of the actuator 68 is shown: however, the 4/2 way valve 48 has two "tines" formed in parallel, and the channels for transporting the liquid within the 4/2 way valve 48 are internal connected, that adjusts the desired conveying direction of the 4/2-way valve 48 depending on the switching position of the actuator 68. Detailed illustrations of the actuator 68 are shown in FIGS. 4 and 5, wherein FIG. 4 shows a top view of the actuator fork 68 and FIG. 5 shows a section A - A marked in FIG. , In normal operation of the 4/2-way valve 48, the actuator 68 through the

Spring elements 62, 64 held and pressed against the lower valve seat 82, for example. The inclination of the two sealing surfaces 80, 81 causes a uniform surface bearing in any position of the 4/2-way valve 48 is given. The illustrated in Figure 3 lower valve seat 82 has to have a survey 88, with a groove of the sealing surface 80 cooperates. The shape of the valve seats 82, 83 according to the invention, a high surface pressure is generated despite a relatively lower contact force. An internal leakage is thereby avoided. A dot-dash line 90 in Figure 5 shows the plastic mold with a specially designed for this application geometry. It can be seen that the bead 78 is compressed in the installed state, so that a good

Setting sealing effect and the urea-water solution is securely held inside the 4/2-way valve 48.

As described above, the actuator 68 has a bead 78 made of plastic. In the area of the implementation of the actuator 68, the bead 78 forms a pivot point for the actuator 68, wherein the actuator 68 is locked between the valve cover 74 and the bottom plate 72. The required for turning or tilting of the actuator 68 bearing is formed by the plastic sheath 76. For sealing to the outside in the bottom plate 72, a flat gasket 92, preferably made of an elastomer used. Figure 6 shows the bottom plate 72 and the

Flat gasket 92 in detail. The bottom plate 72 has in the interior a recess 93 into which the flat gasket 92 can be inserted accurately. The flat gasket 92 is formed as a labyrinth seal and therefore has slots and

Holes 94 to a channel guide, which according to the formation of the channels in the

Bottom plate 72 are executed. A bore 100 serves to receive a pin 101. This will be the

Flat seal 92 additionally locked and at the same time the distance between the valve 48 and the housing part 56 is adjusted by the pin 101.

In this case, 56 sealing ribs 96 are provided in the bottom plate 72 and / or the housing part, which achieve the actual sealing effect. A special geometry, wherein a sealing rib 96 is provided in the interior of the valve 48 and two sealing ribs 96 are provided on the flat gasket 92, ensures a permanent tightness at this

Interface. The flat gasket 92 thus prevents leakage of urea-water solution at the transition between the valve 48 and the housing part 56th

An assembly of the valve 48 will be explained with reference to FIG. During assembly, successively the flat gasket 92 (not shown in FIG. 7) on the bottom plate 72, O-rings 98 as additional sealing means, which place the actuator 68 and finally the valve cover 74 in the manner of a sandwich. There are no screw connections required. The valve cover 74 is formed to encapsulate the entire valve 48. In this way, a structural integral unit is created, which is welded.

On the basis of Figure 8, in particular, the location of the necessary welds are explained. FIG. 8 shows a further longitudinal section through the valve 48. The valve cover 74 encapsulates the valve 48 by being fitted onto the base plate 72. Between bottom plate 72 and valve cover 74 a specially designed for this case Schweißrippengeometrie is provided which generates a bias on this connection by between the bottom plate 72 and the valve cover 74, and between the bottom plate 72 and a separate housing part 56 is formed an oversize, the on the one hand compresses the assemblies and on the other hand during melting during welding, for example, a laser welding, the parts against each other. The bottom plate 72 is preferably made of a laser-transparent and the valve cover 74 made of a laser-absorbing material. The joining surfaces which are used to produce the welds are identified by reference numerals 102a and 102b.

As an alternative, it is also possible to connect the valve 48 with only a single weld 102c, by connecting the connection between the housing part 56 and the Valve cover 74 is executed. For this it is necessary that the housing part 56 is made of laser-transparent and the valve cover 74 made of laser-absorbent material. The advantage of this alternative to the above variant is that it can be dispensed with a weld.

All welds 102 are performed so that the operating pressure occurring in the interior of the valve 48 is maintained.

Claims

claims

1 . A valve (48) comprising an actuator (68) having a housing comprising a bottom plate (72) and a valve cover (74), characterized in that the valve cover (74) and bottom plate (72) are made of plastic, and the valve cover (74) and the bottom plate (72) in the region of a first joining surface (102b) are integrally connected to one another.

2. Valve (48) according to claim 1, characterized in that the joining surface (102b) by a circumferential rib (104) and a complementary to the rib (104) formed counter surface (106) is formed, and that the rib (104) and the mating surface (106) before they are materially connected to each other by a frictional interference fit with each other.

3. Valve (48) according to claim 1 or 2, characterized in that the valve (48) with a housing part (56) of an actuator (52) in the region of a second joining surface (102 a) are integrally connected to one another.

4. Valve (48) according to claim 3, characterized in that the bottom plate (72) of the valve (48) with the housing part (56) in the region of the second joining surface (102 a) before they are materially connected to each other by a non-positive interference fit together are.

5. Valve (48) according to one of the preceding claims, characterized

characterized in that the valve cover (74), the bottom plate (72) and / or the housing part (56) in the region of the joining surfaces (102b, 102a, 102c) by welding, preferably by laser welding or

Electron beam welding, are connected together.

6. Valve (48) according to any one of claims 3 to 5, characterized in that between the valve cover (74) with the housing part (56) in the area a third joining surface (102c) is provided a seal, preferably made of a hardening two-component sealing compound.

7. Valve (48) according to one of the preceding claims, characterized

characterized in that the actuator (68) is partially covered with plastic, and that the bottom plate (72) and the valve cover (74) enclose and fix the actuator (68) so that the actuator (68) between a first and a second switching position is movable.

8. Valve (48) according to one of the preceding claims, characterized

characterized in that the actuator (68) is formed as a fork-shaped lever, and that the free ends of the fork have two substantially oppositely disposed sealing surfaces (80, 81).

9. Valve (48) according to claim 8, characterized in that the two

Seal surfaces (80, 81) converge conically and with valve seats (82, 83) of the valve (48) cooperate.

10. Valve (48) according to one of claims 3 to 9, characterized in that between the bottom plate (72) and the housing part (56) has a

Flat gasket (92) is arranged and thereby chambered.

1 1. Valve (48) according to claim 10, characterized in that the

Flat seal (92) in a correspondingly formed recess (93) of the bottom plate (72) is inserted accurately.

12. Valve (48) according to claim 10 or 1 1, characterized in that in the sealing plate (72) and / or in the housing part (56) in each case at least one sealing rib (96) is formed, and that the sealing rib (96) the

Flat seal (92) elastically deformed.

13. Valve (48) according to one of the preceding claims, characterized

characterized in that the actuator (68) between a first and a second switching position by an actuator (52) is switchable.

14. Valve (48) according to claim 13, characterized in that the actuator (52) comprises an electromagnet which moves a magnet armature (50) axially in the axial direction.

15. Valve (48) according to claim 14, characterized in that the

Electromagnet (52) comprises a profiled pin (54) which is lockable in the housing part (56).