Bypass valve of an exhaust gas treatment system

Abstract

Bypass valve of an exhaust gas treatment system of an internal combustion engine, comprising a valve housing (5) which has an inlet section (6) and two outlet sections (7, 8), namely a first, inlet-proximal section (7) and a second, inlet-distant section (8), wherein a slide (11) is arranged in the valve housing (5) which selectively releases one of the two outlet sections (7, 8), characterized in that an annularly circumferential shoulder (22) is formed in the valve housing (5) between the first outlet section (7) and the second outlet section (8), which in conjunction with a flange (34) formed by the slide (11) and bordering a base (24) of the slide (11) provides a sealing surface that shuts off the second outlet section (8) when the first outlet section (7) is open.

Description

[0001] The invention relates to a bypass valve used in an exhaust gas treatment system of an internal combustion engine according to the preamble of claim 1.

[0002] A bypass valve of this type is known, for example, from JP 2009-36 085 A. The known bypass valve is part of an exhaust system comprising a main catalyst and a bypass catalyst.

[0003] A device disclosed in DE 195 31 212 B4 for opening and closing an exhaust pipe also offers the possibility of selectively opening and closing a main flow channel and a bypass flow channel. A rotatably mounted main spindle, divided into several segments, is provided for actuating this device.

[0004] DE 22 50 155 A describes an exhaust gas bypass valve for internal combustion engines, comprising a closing element connected to a valve tappet. A control cable guided in a flexible sheath is provided for actuating the valve tappet.

[0005] From DE 11 2014 004 546 B4, a valve arrangement is known which is intended to enable the adaptation of an exhaust gas flow by means of an oxidation catalyst. To achieve this objective, the known valve arrangement comprises a bimetallic component that is in contact with the exhaust gases.

[0006] A fluid valve described in DE 197 12 618 A1 is also intended for use in vehicle internal combustion engines. The fluid valve has two valve closing elements for controlling the flow of a fluid, for example, exhaust gas. To prevent over-regulation, one component of the fluid valve is designed as a spring element. This is a spring plate, which, in the form of a shell ring, allows for chipless manufacturing.

[0007] The WO 2017 / 034456A1 reveals in the Fig. 4a, Fig. 4b A thermostatic valve of a coolant circuit of an internal combustion engine. The thermostatic valve, which comprises a cylindrical body and a cylindrical slide guided longitudinally within it, serves, depending on the temperature of the coolant and other parameters, to selectively activate the coolant circuit to the internal combustion engine, in which circuit a radiator is integrated.

[0008] Document DE 10 2012 218 137 A1 describes a bypass valve for boost pressure control in an exhaust gas turbocharger of an internal combustion engine. The valve housing comprises an inlet and an outlet opening, which can be selectively closed by a central slide running within the housing, with opposing plates. Each plate is assigned to one of the openings.

[0009] The invention is based on the objective of providing a bypass valve for an exhaust gas treatment system of an internal combustion engine that is further developed compared to the prior art and is characterized by a design that is easy to manufacture and by the greatest possible avoidance of leakage flows.

[0010] This problem is solved according to the invention by a bypass valve for use in an exhaust gas treatment system of an internal combustion engine, comprising the features of claim 1. The bypass valve, in a basic design known per se, comprises a valve housing having an inlet section and two outlet sections, namely a first section near the inlet and a second section further away from the inlet, wherein a slide is arranged in the valve housing which selectively opens one of the two outlet sections. According to the application, an annular shoulder is formed in the valve housing between the two outlet sections, which, in conjunction with a flange formed by the slide and bordering a base of the slide, provides a sealing surface that closes off the second outlet section when the first outlet section is open.

[0011] In addition to any other sealing points that may be present, this provides a highly effective yet simple seal that is always activated when the first, inflow-adjacent section is open and the second, outflow-distant section is deactivated. The annular shoulder acts as a stop in one axial direction against the slide, which is also commonly referred to as a sliding inner cup. In the opposite axial direction, for example, the base of the slide can abut the base of the valve body. Optionally, detection devices, particularly in the form of switches at end stops, are available to identify the slide's position. Such detection devices can be designed as a separate measuring system or integrated into an actuator that operates the slide.

[0012] According to various possible configurations, the first exhaust section is connected to a catalyst located close to the engine, while the second exhaust section is connected to a second catalyst located further away from the engine. It can be designed so that the exhaust gas flowing through the first catalyst, which occurs, for example, during a cold start or under partial load, is also always routed through the second catalyst.

[0013] Regarding the geometric design of the bypass valve, various configurations are possible. In particular, the central axis of the valve may coincide with the central axis of the inlet section. The outlet sections, for example, branch off at right angles from the inlet section. It is also possible to design the bypass valve as an integral part of the first, engine-adjacent catalyst. In such a case, the bypass channel—that is, the first outlet section or a connecting pipe section—can form an annular gap around the engine-adjacent catalyst.

[0014] Overall, the bypass valve, with its space-saving, robust pot-in-pot design, enables selective, on-demand switching of an exhaust gas flow from an internal combustion engine, particularly a reciprocating engine. This allows a catalyst located close to the engine (i.e., near the cylinder head) and connected to the first exhaust section to quickly reach its required conversion temperature and just as quickly be deactivated by switching to a second exhaust path containing a second catalyst. This prevents degradation of the catalyst located close to the engine, ensuring its continued operational readiness over a long period, despite a lower precious metal loading compared to older solutions.

[0015] In terms of manufacturing technology, the slide valve can, for example, be made of sheet metal. The same applies to the valve housing. In principle, machining of the slide valve and / or the valve housing is also possible.

[0016] Regardless of the manufacturing technology, the slide valve can be connected to an actuating rod, which is displaceable by an actuator and extends from the valve housing. The actuating rod is optionally surrounded by a bellows. Advantageously, the bellows can be designed as a hermetically sealing element. According to a further advantageous embodiment, the bellows is also designed as a spring element that exerts a restoring force on the slide valve. This restoring spring force can act in the direction of a preset or rest position of the bypass valve.

[0017] Adjoining the shoulder that separates the adjacent exhaust sections of the valve housing is an annular gap on the side of the exhaust section furthest from the engine. This gap surrounds the slide valve when it is in the position opening the exhaust section furthest from the engine. This means that the exhaust gas flowing from the slide valve can flow around its entire circumference. This allows the two exhaust sections, or the exhaust lines connected to them, to be arranged with any angular offset from each other, assuming a longitudinal view along the inlet section.

[0018] The exhaust gas, flowing out of the second exhaust section in any direction, first passes through a section of the valve, which is inserted into the first exhaust section, forming a narrow annular gap that allows only minimal leakage. Any leakage that does occur is directed through the first, engine-adjacent catalytic converter, which is not detrimental in terms of emissions or the stress placed on this converter.

[0019] An anti-rotation device can be incorporated between the bypass valve's spool and the valve body. For example, a guide contour acting as an anti-rotation device may include a longitudinal groove formed in the spool and a counter contour engaging in the longitudinal groove, in the form of a stud or ridge integrated into the valve body. It is also possible to integrate an anti-rotation mechanism into the actuator used to operate the spool.

[0020] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1. Schematic representation of an exhaust gas treatment system including a bypass valve, Fig. 2 and Fig. 3. The bypass valve in different settings.

[0021] The Fig. Figures 1 to 3 show, in varying degrees of detail, at least components of a bypass valve 1, which is part of an exhaust aftertreatment system 2 of an internal combustion engine 3, in this case a four-cylinder in-line engine. A valve housing 5 of the bypass valve 1 is connected to an exhaust manifold 4 of the internal combustion engine 3. From the exhaust manifold 4, the exhaust gas from the internal combustion engine 3 enters an inlet section 6 of the bypass valve 1. From the inlet section 6, the exhaust gas can be directed either to a first outlet section 7, located close to the engine, or to a second outlet section 8, located further away from the engine. Outlet lines 9 and 10 are connected to outlet sections 7 and 8. The first outlet line 9 leads to a first catalyst 27, located close to the engine, from where the exhaust gas flows into a second catalyst 28, located further away from the engine. The second exhaust line 10, on the other hand, leads the exhaust gas directly to the second, engine-distant catalyst 28.On the output side, an exhaust pipe 29 is connected to the second catalyst 28.

[0022] A slide valve 11 is arranged in the valve housing 5 to selectively direct the exhaust gas through the first outlet 9 or through the second outlet 10. The common central axis of the slide valve 11 and the valve housing 5 is designated MA. VR denotes the adjustment direction of the slide valve 11, i.e., the axial direction of the valve housing 5. Exhaust gas flows indicated in the figures are designated AS.

[0023] The slide valve 11 has a straight tube shape with a cylindrical section 12 extending over almost its entire length. A lateral opening 13 is located in the cylindrical section 12, through which exhaust gas can be selectively discharged into either the first outlet 9 or the second outlet 10. One end of the slide valve 11 is designated 14. An actuating rod 15 is connected to the end 14 and extends from the valve housing 5. For this purpose, an opening 17 is provided in the end of the valve housing 5, designated 16, through which the actuating rod 15 passes.

[0024] The valve housing 5 has a sleeve-shaped section 18 in which the slide 11 is mounted for longitudinal displacement. A first, inlet-side open section 19 of the sleeve-shaped section 18 has a cylindrical shape, as does a second section 20 with a comparatively large diameter. The first section 19 contains a first outlet-side opening 23, to which the first outlet line 9 is connected. Similarly, the second outlet line 10 connects to a second outlet-side opening 24, which is located in the second, enlarged section 20. The cylindrical section 12 of the slide 11 almost completely fills the free cross-section of the first section 19. In contrast, an annular space 21 is formed between the cylindrical section 12 and the wall of the valve housing 5 in the second section 20.The annular space 21 extends in the axial direction of the bypass valve 1 from a ring-shaped circumferential shoulder 22, which separates the sections 19, 20 from each other, to the bottom 16 of the valve housing 5. Due to this annular space 21, the second outflow-side opening 24 can be located at any point on the circumference of the second section 20.

[0025] Is the first outlet line 9 open, as shown in Fig. As shown in Figure 2, a flange 34, which is formed at the transition between the cylindrical section 12 of the slide 11 and its bottom 14, seals against the shoulder 22, thus forming a static seal at this point which prevents any inflow of exhaust gas into the second outlet pipe 10.

[0026] To prevent rotation of the slide 11 in the valve housing 5, the slide 11 has a guide contour 25 designed as a longitudinal groove, into which a knob-like counter contour 26 of the valve housing 5 engages. The free flow cross-section in the cylindrical section 12 of the slide 11 is only minimally reduced by the guide contour 25. In the exemplary embodiment, the contours 25, 26 are located on the side of the sleeve-shaped area 18 diametrically opposite the openings 23, 24.

[0027] An actuator 30 is provided for actuating the bypass valve 1. This actuator is an electromechanical actuator connected to the actuating rod 15. Electrical lines for supplying power to the actuator 30 are designated 31. A ring disc 32 is gas-tightly attached to the actuating rod 15; it may also be integrally formed with the actuating rod 15. A bellows 33 is inserted between the base 16 of the valve housing 5 and the ring disc 32, ensuring gas tightness on both end faces, i.e., towards the base 16 and towards the ring disc 32. The interior of the valve housing 5 is thus hermetically sealed from the outside. Reference symbol list 1 bypass valve 2 Exhaust gas treatment system 3 Internal combustion engine 4 exhaust manifolds 5 Valve housings 6 Inlet section 7 first, engine-adjacent exhaust section 8 second, engine-remote exhaust section 9 first outlet line 10 second outflow line 11 sliders 12 cylindrical section of the slide 13 lateral openings in the cylindrical section of the slide 14 Bottom of the slide 15 Actuating rod 16 Bottom of the valve housing 17 Opening in the bottom of the valve housing 18 sleeve-shaped area of ​​the valve housing 19 first section of the sleeve-shaped area of ​​the valve housing 20 second, extended section of the sleeve-shaped area 21 Annular space between the valve and the extended section 22 ring-shaped shoulder 23 first outlet-side opening of the housing 24 second outlet-side opening of the housing 25 Guide contour of the slide 26 Counter contour of the housing 27 first, engine-mounted catalyst 28 second, remote catalytic converter 29 Exhaust pipe 30 actuator 31 electrical line 32 ring disc 33 Bellows 34 flange AS exhaust gas flow MA Central Axis VR adjustment direction

Claims

[1] Bypass valve of an exhaust gas treatment system of an internal combustion engine, comprising a valve housing (5) which has an inlet section (6) and two outlet sections (7, 8), namely a first inlet-proximal section (7) and a second inlet-distant section (8), wherein a slide (11) is arranged in the valve housing (5) which selectively releases one of the two outlet sections (7, 8), characterized by , that between the first outlet section (7) and the second outlet section (8) an annularly circumferential shoulder (22) is formed in the valve housing (5), which in conjunction with a flange (34) formed by the slide (11) and bordering a bottom (24) of the slide (11) provides a sealing surface that shuts off the second outlet section (8) when the first outlet section (7) is open. [2] Bypass valve according to claim 1, characterized by, that the first exhaust section (7) is connected to a catalyst close to the engine (27) and the second exhaust section (8) is connected directly to a catalyst far from the engine (28). [3] Bypass valve according to claim 1 or 2, characterized by , that the central axis (MA) of the slide (11) coincides with the central axis of the inlet section (6) and the outlet sections (7, 8) branch off at right angles from the inlet section (6). [4] Bypass valve according to any one of claims 1 to 3, characterized by , that the slide (11) is designed as a sheet metal part. [5] Bypass valve according to any one of claims 1 to 4, characterized by , that an actuating rod (15) connected to the slide (11) and led out of the valve housing (5) is surrounded by a bellows (33). [6] Bypass valve according to claim 5, characterized by , that the bellows (33) is designed as a hermetically sealing element. [7] Bypass valve according to claim 5 or 6, characterized by, that the bellows (33) is designed as a spring element which exerts a restoring force on the slide (11). [8] Bypass valve according to any one of claims 1 to 7, characterized by , that the two outflow sections (7, 8) - with a view in the longitudinal direction of the inflow section (6) - are angularly offset from each other. [9] Bypass valve according to any one of claims 1 to 8, characterized by , that the slide (11) forms a guide contour (25) which interacts with a housing-side counter contour (26) and serves to prevent rotation between the slide (11) and the valve housing (5).

Images