THROTTLE VALVE DEVICE FOR AN EXHAUST OR AIR INTAKE SYSTEM OF AN INTERNAL COMBUSTION ENGINE

Description

[0001] The invention relates to a throttle valve device for an exhaust system or an intake air system of an internal combustion engine, comprising a throttle valve housing which has an inner housing element defining a flow channel and an outer housing element radially surrounding the inner housing element, wherein an air gap is provided between the outer housing element and the inner housing element, and a throttle valve which is arranged in the flow channel and is pivotably mounted on the throttle valve housing via a valve shaft projecting into the flow channel.

[0002] Throttle valve devices for internal combustion engines are known from the prior art and are provided in an intake air duct or in an exhaust air duct of the internal combustion engine. The throttle valve device arranged in the intake air duct serves, for example, to adjust the fuel-air ratio in the combustion process of the internal combustion engine or to adjust an exhaust gas recirculation rate into the internal combustion engine. In the exhaust air duct, the throttle valve device serves to influence noise emissions and to influence the back pressure in the exhaust air duct; such throttle valve devices are also referred to as acoustic valves.

[0003] Such a throttle valve device is disclosed in WO 2017 / 216241 A1. The throttle valve device has a multi-part throttle valve housing, which comprises an inner housing element and an outer housing element radially surrounding the inner housing element. The inner housing element defines a flow channel, through which, for example, the exhaust gases of the internal combustion engine flow. A throttle valve is arranged in the flow channel and is attached to a rotatable valve shaft. The rotatable valve shaft is non-rotatably connected to an actuator and projects into the flow channel through an opening provided in the throttle valve housing. By actuating the actuator, the throttle valve can be adjusted between an open position and a closed position. In its closed position, the throttle valve rests against a valve stop provided on the inner housing element and projecting into the flow channel.

[0004] The inner and outer housing elements are designed such that an air gap exists between the outer circumferential surface of the inner housing element and the inner circumferential surface of the outer housing element. This air gap acts as air gap insulation, thereby reducing heat transfer between the flow channel and the external environment. This air gap insulation protects the actuator from thermal overheating.

[0005] Another embodiment of a flap device with an inner housing element, an outer housing element, and an air gap radially limited by the inner and outer housing elements is known from US 2015 / 0226161 A1. A sleeve is arranged in the area of ​​a flap shaft projecting into a flow channel limited by the inner housing element. This sleeve, together with the outer housing element, forms a labyrinth seal for sealing in the longitudinal direction of the flap shaft. Further embodiments of a flap device with an inner housing element or inner wall, an outer housing element or outer wall, and an air gap located between the inner and outer housing elements or between the inner and outer walls are known from EP 1 243 774 A2 and WO 2021 / 037356 A1.

[0006] Insufficient sealing of the air gap against the flow channel leads to a reduction in air gap insulation and possibly to a complete loss of air gap insulation, whereby with a high leakage rate of the gas flowing through the flow channel into the air gap a temperature is established in the air gap which corresponds to the temperature of the gas flowing through the flow channel.

[0007] The task, therefore, is to provide a throttle valve device that reliably reduces heat transfer between the flow channel and the outside environment.

[0008] This problem is solved by a throttle valve device having the features of main claim 1.

[0009] By providing a sealing ring arranged coaxially to the throttle shaft between the inner housing element and the outer housing element, the thermal insulation of the flow channel from the external environment is ensured by significantly reducing the leakage flow of the gas flowing through the throttle valve housing into the air gap, thus ensuring the air gap insulation of the flow channel.

[0010] The flap shaft protrudes into the flow channel through overlapping openings provided in the inner and outer housing elements. These overlapping openings create a leakage path between the flow channel and the air gap. The sealing ring, positioned between the inner and outer housing elements and coaxially with the flap shaft, completely seals the air gap in the area of ​​the flap shaft against the flow channel, thus closing the leakage path caused by the openings for the flap shaft. The sealing ring rests against an outer circumferential surface of the inner housing element via a first contact surface and against an inner circumferential surface of the outer housing element via a second contact surface.

[0011] The outer housing element has at least one bearing bushing for receiving a throttle valve bearing, wherein the bearing bushing has an annular groove on a surface facing the inner housing element, in which the sealing ring is arranged, the sealing ring bearing against a surface of the inner housing element facing the annular groove. In this way, the sealing ring can be easily and reliably arranged on the outer housing element, and unwanted displacement of the sealing ring during assembly or operation of the throttle valve device is prevented by the arrangement of the sealing ring in the annular groove.

[0012] Preferably, the sealing ring is designed as a high-temperature seal, and the sealing ring can preferably withstand thermal stresses up to a temperature of 1200 °C of the gas flowing through the flow channel. This ensures air gap insulation even at high gas temperatures. With such a seal, the throttle valve device can be used as an exhaust valve device.

[0013] In a preferred embodiment, the sealing ring has low thermal conductivity, thereby reducing heat transfer between the inner and outer housing elements and thus between the flow channel and the external environment. The sealing ring, which rests against both the inner and outer housing elements, transfers virtually no heat between them.

[0014] Preferably, the sealing ring is made of ceramic fibers, wherein the sealing ring made of the ceramic fibers can be used up to a temperature of 1200 °C of the gas flowing through the flow channel and at the same time has low thermal conductivity.

[0015] In a preferred embodiment, the sealing ring is a stuffing box, which is used as a static seal to seal a gap between components that are not moving relative to each other. Stuffing boxes are made, for example, from aramid, graphite, PTFE, or ceramic fibers. When installed, the stuffing box is compressed between the two components, thereby creating the seal. By designing the sealing ring as a stuffing box, the manufacturing costs of the throttle valve assembly can be reduced because the stuffing box can be produced simply and cost-effectively.

[0016] Preferably, the throttle shaft is supported on both sides of the throttle body, the throttle shaft extending through two overlapping first openings in the inner and outer housing elements and through two overlapping second openings in the inner and outer housing elements, with a first sealing ring arranged between the inner and outer housing elements in the region of the first openings and a second sealing ring arranged between the inner and outer housing elements in the region of the second openings. In a preferred embodiment, a first bearing bushing is arranged at the first opening and a second bearing bushing is arranged at the second opening. The double-sided support of the throttle shaft reliably prevents bending of the throttle shaft and ensures proper operation of the throttle device.The two sealing rings ensure that the air gap is reliably sealed against the flow channel, even when the flap shaft is supported on both sides.

[0017] Preferably, the bearing bushing has a stepped outer surface, wherein the bearing bushing rests against the outer housing element via a first step of the stepped outer surface and against the inner housing element via a second step of the stepped outer surface. The first step has a larger diameter than the second step. The sealing ring is preferably arranged in the radially extending region between the first and second steps of the stepped outer surface, the sealing ring being pre-tensioned against the radially extending region and against an outer circumferential surface of the inner housing element. The sealing ring is pre-tensioned in the direction of the flap shaft's axis of rotation and thus axially.

[0018] Preferably, the air gap is a cavity bounded on all sides by the inner housing element and the outer housing element, thereby reliably preventing the inflow of hot and thermally conductive substances and ensuring air gap insulation.

[0019] Preferably, the inner housing element and the outer housing element are joined together by a material bond, preferably via a welded connection, thereby creating a reliable and fluid-tight connection between the inner and outer housing elements. This material bond reliably prevents leakage of the gas flowing through the flow channel into the air gap, thus ensuring thermal insulation.

[0020] Preferably, the inner housing element is welded to the outer housing element exclusively at an axial end located upstream of the throttle valve in the flow direction. This reliably prevents leakage of the gas flowing through the flow channel into the air gap, while simultaneously preventing gas from entering the air gap at the axial end located downstream of the throttle valve. Welding the inner housing element to the outer housing element only at one axial end reduces the manufacturing costs of the throttle valve housing. Furthermore, this prevents unexpected weld failure between the inner and outer housing elements due to differing thermal expansion rates.

[0021] In a preferred embodiment, the outer housing element is made from two outer housing half-shells, and the inner housing element is made from two inner housing half-shells. This allows the sealing ring to be mounted in a simple and cost-effective manner, wherein, during the assembly process, the inner housing half-shells are joined to form an inner housing element with an annular cross-section, and then the formed outer housing half-shells are placed over the joined inner housing element, with the sealing ring being inserted into the air gap after the inner housing element has been joined and before the outer housing element has been assembled.

[0022] The design of the inner and outer housing elements as half-shells simplifies the manufacturing and assembly of the throttle body. Manufacturing costs can be reduced by producing the inner and outer housing half-shells from inexpensive sheet metal blanks, such as rectangular blanks or directly from a coil, and by forming these blanks using a cost-effective process, particularly deep drawing.

[0023] Preferably, the inner housing half-shells and / or the outer housing half-shells are joined together by a material bond, in particular by a welded connection, thereby creating a reliable and fluid-tight connection between the half-shells.

[0024] This creates a throttle valve device for an exhaust system or an intake air system of an internal combustion engine, in which the thermal insulation of the flow channel from the outside environment is ensured, with the simple and cost-effective sealing ring sealing the air gap in the area of ​​the flap shaft projecting into the flow channel between the outer housing element and the inner housing.

[0025] An embodiment of a throttle valve device according to the invention for an exhaust system or an intake air system of an internal combustion engine is shown in the figures and described below. Figure 1 shows a perspective view of a throttle valve device according to the invention, and Figure 2 shows a cross-sectional view of a throttle body of the throttle valve assembly. Figure 1 .

[0026] The Figure 1Figure 1 shows a throttle valve assembly 10 for an exhaust system of an internal combustion engine, wherein the throttle valve assembly 10 comprises an actuator housing 20 and a throttle valve housing 30. The actuator housing 20 is multi-part and has a housing base 22 and a cover 24 screwed to the housing base 22, wherein the housing base 22 is made of a metallic material and the cover 24 is made of a plastic. A drive device (not shown in the figures) with associated electronics is arranged in the actuator housing 20, wherein the drive device drives an actuator shaft 26 projecting from the actuator housing 20.

[0027] The throttle valve housing 30 is attached to the housing base 22 of the actuator housing 20 via a retaining device 50, the retaining device 50 having several retaining arms 52, 54, 56 which are fixedly arranged on the throttle valve housing 30, for example, welded on. The retaining arms 52, 54, 56 provided on the throttle valve housing 30 are each fastened to the housing base 22 by a screw.

[0028] A throttle valve 40 is arranged in the throttle body 30 and is attached to a throttle shaft 42 rotatably mounted about a pivot axis 41. The end of the throttle shaft 42 protruding from the throttle body 30 is connected via a coupling 28 to the end of the actuator shaft 26 protruding from the actuator housing 20 in a rotationally fixed manner.

[0029] The clutch 28 is radially surrounded by a spring 29, in particular a torsion spring, wherein the spring 29 is rigidly connected with a first leg to the throttle body 30 and with an opposing, second leg to the throttle shaft 42. The connection of the spring 29 to the throttle shaft 42 is effected via a plate-like transmission element 27 which is rotationally fixed to the throttle shaft 42.

[0030] In the installed state, the spring 29 loads the flap shaft 42 in the circumferential direction such that the throttle valve 40 is rotated into a fail-safe position when the drive device is inactive, with the transmission element 27 bearing against a stop 31 provided on the retaining leg 56 and thus on the throttle valve housing 30 in the fail-safe position.

[0031] Furthermore, the spring 29 is axially compressed during the assembly process, which causes the spring 29 to exert an axial load on the flap shaft 42. The spring force acts in the direction of the throttle valve housing 30.

[0032] The Figure 2 The throttle body 30 is shown. The throttle body 30 is double-walled and comprises an outer housing element 32 and an inner housing element 34.

[0033] The inner housing element 34 radially delimits a flow channel 36 and has a Figure 1 The throttle valve 40, located in the flow channel 36, is closed by the flap stop 38 shown, and thus rests against the flap stop 38 in its closed position, closing the flow channel 36. With the actuator inactive, the throttle valve 40 is moved to its open position by the circumferentially acting load on the spring 29.

[0034] The outer housing element 32 is made from two outer housing half-shells 90, 92 and the inner housing element 34 is made from two inner housing half-shells 94, 96.

[0035] The outer housing half-shells 90, 92 are manufactured from a rectangular sheet metal cutout and formed into their respective predefined shapes by a deep-drawing process, so that, in the assembled state, the outer housing half-shells 90, 92 form, among other things, an outer housing element with a ring-shaped cross-section. The inner housing half-shells 94, 96 are manufactured in the same way.

[0036] In the assembly process of the throttle valve housing 30, the inner housing halves 94, 96 are first welded together in a connection plane 100 aligned longitudinally to the axis of rotation 41 of the throttle shaft 42 and longitudinally to a longitudinal axis of the flow channel 36. In the next step, the outer housing halves 90, 92 are placed over the already welded inner housing element 34 and welded together in a connection plane 102 aligned transversely to the axis of rotation of the throttle shaft 42. Subsequently, the inner housing element 34 is welded to the outer housing element 32 with an axial end arranged in the flow direction upstream of the throttle valve 40, thus preventing exhaust gas from flowing into the air gap 80.

[0037] In its fully assembled state, the outer housing element 32 rests with its inner circumferential surface 33 against the outer circumferential surface 35 of the inner housing element 34, with the inner circumferential surface 33 and the outer circumferential surface 35 having a mean diameter Dm in the contact area. In the axially central region of the throttle valve housing 30, the inner circumferential surface 33 of the outer housing element 32 has a diameter Ds larger than the mean diameter Dm. The increased diameter Ds creates a circumferential air gap 80, which is bounded on all sides by the outer housing element 32 and the inner housing element 34. The air gap 80 serves as thermal insulation between the flow channel 36 and the external environment, and thus between the flow channel 36 and the actuator housing 20.

[0038] The inner housing element 34 and the outer housing element 32 each have two opposing openings 60, 62, 64, 66, wherein the openings 60, 62 on the inner housing element 34 and the openings 64, 66 on the outer housing element 32 overlap, and the flap shaft 42 extends through the openings 60, 62, 64, 66. A bearing receiving bushing 70, 72 is provided in each of the openings 64, 66 of the outer housing element 32, wherein each bearing receiving bushing 70, 72 contains a flap shaft bearing (not shown in the figures) and a sealing surface. The axial preload of the flap shaft 42 by the spring 29 presses the sealing surface against a counter-sealing surface. The flap shaft bearing is designed as a plain bearing, for example, as a plain bearing sleeve. Alternatively, the flap shaft bearing can be designed as a rolling bearing.

[0039] In this case, the axial preload of the flap shaft can be used for the axial preload of the rolling bearings.

[0040] The bearing bushings 70, 72 have a stepped outer surface 86, 88 at their end facing the flow channel 36. The bearing bushing 70, 72 bears radially against the outer housing element 32 via a first step with a larger diameter and against the inner housing element 34 via a second step with a smaller diameter relative to the first step. Radially between the two steps of the stepped outer surface 86, 88, the bearing bushings 70, 72 each have an axially extending, annular groove 74, 76. A sealing ring 82, 84 is arranged in each of the annular grooves 74, 76, with the surfaces of the sealing rings 82, 84 facing away from the annular groove 74, 76 bearing against the outer circumferential surface 35 of the inner housing element 34.

[0041] The annular grooves 74, 76 and the sealing rings 82, 84 are coaxial to the flap shaft 42 and thus arranged in an area directly adjacent to the openings 60, 62, 64, 66, whereby the air gap 80 is sealed by the sealing rings 82, 84 directly at the openings 60, 62, 64, 66 against the flow channel 36.

[0042] The sealing rings 82 and 84 are designed as high-temperature seals for use with the throttle valve assembly 10 in an exhaust system. Furthermore, the sealing rings 82 and 84 have low thermal conductivity to minimize heat transfer between the inner housing element 34 and the outer housing element 32. Consequently, the sealing rings 82 and 84 are fitted with a ceramic fiber stuffing box, such as a ceramic fiber stuffing box that can be used at high temperatures, up to 1200 °C, and exhibits low thermal conductivity.

[0043] A throttle valve device 10 is thus created for an exhaust stream or an intake air stream of an internal combustion engine, in which the thermal insulation of the flow channel 36 from the outside environment is ensured, wherein the simple and cost-effective sealing ring 82, 84 reliably seals the air gap 80 in the area of ​​the flap shaft 42 projecting into the flow channel 36 between the outer housing element 32 and the inner housing element 34.

[0044] It should be clear that the scope of protection is not limited to the described embodiment, but that various modifications are conceivable. For example, the inner and outer housing elements 32, 34 or the throttle valve 40 can be designed differently.

Claims

1. A throttle valve device for an exhaust system or a supply air system of an internal combustion engine, with a throttle valve housing (30) which has an inner housing element (34), which delimits a flow duct (36), and an outer housing element (32), which radially surrounds the inner housing element (34), an air gap (80) being provided between the outer housing element (32) and the inner housing element (34), and a throttle valve (40), which is situated in the flow duct (36) and is mounted pivotably on the throttle valve housing (30) via a valve shaft (42) projecting into the flow duct (36), characterized in that a sealing ring (82, 84), which is arranged coaxially to the valve shaft (42), is provided between the inner housing element (34) and the outer housing element (32), wherein on the outer housing element (32) at least one bearing receiving bush (70, 72) is provided for receiving a valve bearing, wherein the bearing receiving bush (70, 72) has on a surface facing the inner housing element (34) an annular groove (74, 76), in which the sealing ring (82, 84) is arranged, wherein the sealing ring (82, 84) lies on a surface of the inner housing element (34) facing the annular groove (74, 76).

2. The throttle valve device according to Claim 1, characterized in that the sealing ring (82, 84) is embodied as a high temperature seal.

3. The throttle valve device according to Claim 1 or 2, characterized in that the sealing ring (82, 84) has a low thermal conductivity.

4. The throttle valve device according to Claim 2 and 3, characterized in that the sealing ring (82, 84) is produced from ceramic fibres.

5. The throttle valve device according to one of the preceding claims, characterized in that the sealing ring (82, 84) is a stuffing box.

6. The throttle valve device according to one of the preceding claims, characterized in that the valve shaft (42) is mounted on both sides on the throttle valve housing (30), wherein the valve shaft (42) extends through two first openings (60, 64), overlapping each other, on the inner housing element (34) and on the outer housing element (32), and by two second openings (62, 66), overlapping each other, on the inner housing element (34) and outer housing element (32), and wherein a first sealing ring (82) is arranged between the inner housing element (34) and the outer housing element (32) in the region of the first openings (60, 64), and a second sealing ring (84) is arranged between the inner housing element (34) and the outer housing element (32) in the region of the second openings (62, 66).

7. The throttle valve device according to one of the preceding claims, characterized in that a first bearing receiving bush (70) is arranged at the first opening (60), and a second bearing receiving bush (72) is arranged at the second opening (62).

8. The throttle valve device according to one of the preceding claims, characterized in that the bearing receiving bush (70, 72) has a steplike outer surface, wherein the bearing receiving bush (70, 72) lies via a first step of the steplike outer surface on the outer housing element (32), and lies via a second step of the steplike outer surface on the inner housing element (34).

9. The throttle valve device according to one of the preceding claims, characterized in that the air gap (80) is a cavity delimited on all sides by the inner housing element (34) and the outer housing element (32).

10. The throttle valve device according to one of the preceding claims, characterized in that the inner housing element (34) and the outer housing element (32) are connected to one another in a materially bonded manner.

11. The throttle valve device according to Claim 10, characterized in that the inner housing element (34) is welded with the outer housing element (32) exclusively with an axial end arranged in flow direction before the throttle valve (40).

12. The throttle valve device according to one of the preceding claims, characterized in that the outer housing element (32) is produced from two outer housing half shells (90, 92), and the inner housing element (34) is produced from two inner housing half-shells (94, 96).

13. The throttle valve device according to Claim 12, characterized in that the inner housing half-shells (94, 96) and / or the outer housing half-shells (90, 92) are connected to one another in a materially bonded manner.