Valve device for an internal combustion engine

Description

[0001] The invention relates to a flap device for an internal combustion engine, comprising a flow housing which defines at least one flow channel, a flap shaft which is radially and axially mounted on the flow housing, and at least one flap body which is mounted on the flap shaft and is arranged in the flow channel, wherein the flap body together with the flap shaft is rotatable about a longitudinal axis of the flap shaft between different positions.

[0002] Such flap devices are used, for example, as exhaust gas recirculation flaps or exhaust gas return valves in low-pressure or high-pressure exhaust circuits. It is also known to provide such flap devices in an air intake duct of an internal combustion engine, in particular as a throttle valve.

[0003] Such a flap device is disclosed, for example, in WO 2017 / 182233 A1, which does not disclose a redundant, wear-compensating second axial bearing that is only switched on in the event of wear of the first axial bearing.

[0004] The flap device comprises an exhaust gas flow housing that defines an exhaust gas flow channel. A flap body is arranged within the exhaust gas flow channel and is attached to a flap shaft that is rotatably mounted on the exhaust gas flow housing and projects into the exhaust gas flow channel. Two radial bearings are provided for the rotatable mounting; these are aligned with each other and located on opposite sides of the flap body. The flap shaft is also axially supported on the exhaust gas flow housing via a thrust bearing. A counter bearing element of the thrust bearing is attached to the flap shaft, and a bearing element of the thrust bearing is attached to the flow housing. The flap shaft is axially loaded by a spring element, which presses the counter bearing element with an axial bearing surface against an axial bearing surface of the thrust bearing element.

[0005] A disadvantage of this type of flap design is that the bearing surfaces of the bearing element and the counter-bearing element wear down with increasing operation. Due to the wear of the bearing element and / or the counter-bearing element, i.e., the material removal from the bearing surfaces of the bearing element and / or the counter-bearing element, the flap shaft, and consequently the flap body attached to the flap shaft, shifts axially in such a way that the flap body is no longer centrally located in the flow channel. This can lead to increased leakage when the flap body is closed and to the flap body jamming during adjustment.

[0006] The task is therefore to provide a flap device for an internal combustion engine of a motor vehicle in which the wear-related axial displacement of the flap shaft and the flap body can be reduced, thereby ensuring a reliable seal in the closed position of the flap body over the entire service life and preventing the flap body from jamming during adjustment.

[0007] This problem is solved by a flap device for an internal combustion engine of a motor vehicle with the features of claim 1.

[0008] For the axial support of the flap shaft, the flap device has a first axial bearing and a second axial bearing. Both axial bearings each have a bearing element and a counter-bearing element, wherein the bearing element is provided on the flow housing, in particular is attached to the flow housing or is manufactured integrally with the flow housing, and the counter-bearing element is provided on the flap shaft, i.e., attached to the flap shaft or manufactured integrally with the flap shaft.

[0009] In its new state, the counter bearing element of the first axial bearing rests axially against the corresponding bearing element, while the counter bearing element of the second axial bearing is spaced apart from the corresponding bearing element. This means that a relatively small gap exists between the counter bearing element and the bearing element of the second axial bearing. Thus, in its new state, the axial support of the flap shaft is provided exclusively by the first axial bearing. During operation, the bearing elements that move and slide relative to each other—that is, the bearing element and / or the counter bearing element of the first axial bearing—wear. This causes the flap shaft to shift axially by the amount of wear. Consequently, the flap shaft and the counter bearing element of the second axial bearing, which is located on the flap shaft, also shift.As soon as the wear amount of the first axial bearing exceeds the gap width of the gap between the bearing element and the counter bearing element of the second axial bearing, contact occurs between the counter bearing element of the second axial bearing and the bearing element of the second axial bearing, whereby the flap shaft is additionally axially supported by the second axial bearing.

[0010] In this way, the displacement of the valve shaft due to wear of the first axial bearing can be reduced, thereby preventing undesirably high leakage when the valve body is closed and jamming of the valve body during adjustment. This can increase the service life of the valve assembly and / or prevent premature failure of the valve assembly.

[0011] Preferably, a radial bearing is provided for the radial support of the flap shaft, which forms the bearing element of the second axial bearing, wherein an end face of the radial bearing interacts with an axial contact surface of the counter bearing element of the second axial bearing. This eliminates the need for a separate component forming the bearing element, thereby simplifying assembly and reducing assembly and manufacturing costs.

[0012] In a preferred embodiment, the radial bearing is designed as a plain bearing and comprises a bearing sleeve, wherein the bearing sleeve is fixedly arranged on the flow housing, in particular in the axial and radial directions. The annular end face of the bearing sleeve serves for the axial support of the flap shaft. In this way, the axial support can be implemented in a simple and cost-effective manner.

[0013] Preferably, the flap body forms the counter bearing element of the second axial bearing, wherein the flap body has the contact surface axially facing the bearing element of the second axial bearing. This eliminates the need for a separate component to provide the counter bearing element, thereby reducing assembly and manufacturing effort. For this purpose, the flap body comprises an annular contact surface which has a diameter at least slightly smaller than that of the bearing element, ensuring that the flap body's contact surface rests exclusively against the bearing element.

[0014] In a preferred embodiment, the counter bearing element has a ceramic element on a side facing the bearing element, which reduces the sliding friction of the first axial bearing and reduces leakage flow from the flow channel through the first axial bearing. Alternatively, the ceramic element can also be provided on the bearing element and slide on the counter bearing element.

[0015] In a preferred embodiment, the ceramic element has a conical contact surface which rests against a conical counter-contact surface provided on the bearing element. This allows the contact area between the ceramic element and the bearing element or the counter-bearing element to be increased, thereby further improving the seal and thus reducing the leakage flow from the flow channel.

[0016] Preferably, a first flap body and a second flap body are attached to the flap shaft, wherein the first flap body is arranged in a first flow channel limited by the flow housing and the second flap body is arranged in a second flow channel limited by the flow housing, wherein a third axial bearing is provided, which is designed such that the counter bearing element and the bearing element of the third axial bearing are initially spaced apart from each other and only come into contact with each other when there is advanced wear of the bearing elements and / or the counter bearing elements of the first axial bearing and the second axial bearing and an axial displacement of the flap shaft and the counter bearing element of the third axial bearing caused by the wear.In its new state, a gap exists between the counter bearing element and the bearing element of the third axial bearing. This gap is wider than the gap between the bearing element and the counter bearing element of the second axial bearing. The counter bearing element of the third axial bearing only serves as additional axial support for the flap shaft when the bearing elements and / or counter bearing elements of the first and second axial bearings are so worn, and the flap shaft is displaced due to wear, that the gap between the counter bearing element and the bearing element of the third axial bearing no longer exists. This further extends the service life of the flap device.

[0017] Preferably, a second radial bearing is provided, wherein the second radial bearing forms the bearing element of the third axial bearing and the second flap body forms the counter bearing element of the third axial bearing, with an axial contact surface of the flap body interacting with an axial contact surface of the radial bearing facing the flap body. This eliminates the need for additional components to provide the third axial bearing, thereby reducing assembly and manufacturing effort.

[0018] In a preferred embodiment, a third radial bearing is provided, wherein the first flap body is arranged axially between the first radial bearing and the second radial bearing, and the second flap body is arranged axially between the second radial bearing and the third radial bearing. This allows the relatively long flap shaft with two flap bodies to be reliably radially supported.

[0019] In a preferred embodiment, a spring retaining element is attached to an end projecting from the flow housing, wherein a spring element is pre-tensioned between the spring retaining element and the flow housing such that the counter bearing elements are axially loaded in the direction of the bearing elements of the axial bearings. This ensures reliable axial support of the flap shaft.

[0020] Preferably, the flow channel is an exhaust gas flow channel, wherein the exhaust gas flowing through the exhaust gas flow channel has a relatively high temperature of several hundred degrees Celsius. The gaps present in the new condition of the flap device between the bearing elements and the counter-bearing elements of the second axial bearing and the third axial bearing are also present at high exhaust gas temperatures and the resulting thermal expansion, so that in the new condition of the flap device, the flap shaft is axially supported exclusively by the first axial bearing, and only when the first axial bearing is worn do the other axial bearings serve to axially support the flap shaft.

[0021] This provides a flap device for an internal combustion engine, in which wear-related axial displacement of the flap shaft is reduced, thereby preventing undesirable, high leakage when the flap body is closed and jamming of the flap body during adjustment. This can increase the service life of the flap device and / or prevent premature failure of the flap device.

[0022] An embodiment of a flap device according to the invention for an internal combustion engine is shown in the figure and is described below.

[0023] The figure shows a sectional view of a flap device according to the invention.

[0024] The figure shows a flap device 10 for an internal combustion engine of a motor vehicle, wherein the flap device 10 is designed as an exhaust flap device and serves, for example, as an exhaust gas flap or as an exhaust gas recirculation valve.

[0025] The flap device 10 comprises a flow housing 12, which defines a first flow channel 14 and a second flow channel 16. The flow housing 12 is also made of a metallic material.

[0026] The flap device 10 further comprises a flap shaft 18 rotatably mounted on the flow housing 12, to which two flap bodies 20, 22 are attached, wherein a first flap body 20 is arranged in the first flow channel 14 and the second flap body 22 is arranged in the second flow channel 16. The flap shaft 18 is made in one piece and extends through the two flow channels 14, 16, wherein the flow housing 12 has a transverse bore 15 between the two flow channels 14, 16, a blind bore 17 on a side of the second flow channel 16 facing away from the first flow channel 14, and a through bore 19 on a side of the first flow channel 14 facing away from the second flow channel 16.The flap shaft 18 protrudes from the through-bore 19 in the flow housing 12, with an actuator (not shown in the figure) engaging the protruding section of the flap shaft 18. This actuator allows the flap shaft 18 and the flap bodies 20, 22 to be rotated between different positions. By adjusting the flap shaft 18 and the flap bodies 20, 22, the flow cross-section defined by the respective flap body 20, 22 and an inner circumferential surface of the flow channels 14, 16 can be changed. Since the flap bodies 20, 22 are attached to a single flap shaft 18, the adjustment of the flow cross-section in both flow channels 14, 16 necessarily occurs simultaneously.

[0027] The flap shaft 18 is rotatably, i.e. radially, mounted on the flow housing 12. For this purpose, a radial bearing 60, 70, 80 in the form of a bearing sleeve 64, 74, 84 is provided in each of the transverse bore 15, the blind bore 17 and the through bore 19, wherein the flap shaft 18 is supported on the flow housing 12 in the axial and radial directions via the bearing sleeves 64, 74, 84.

[0028] The flap shaft 18 is also axially supported on the flow housing 12. Three axial bearings 30, 40, 50 are provided for this purpose.

[0029] A first axial bearing 30 comprises a bearing element 32, a counter bearing element 34, and a ceramic element 36. The bearing element 32 is arranged within the through-opening 19 and attached to the flow housing 12. The bearing element 32 has an annular cross-section and is pressed into the flow housing 12 via an outer circumferential surface, so that the bearing element 32 is fixedly arranged on the flow housing 12, at least in the axial direction. The counter bearing element 34 is attached to the flap shaft 18, for example, by means of a press fit. The ceramic element 36 is arranged between the bearing element 32 and the counter bearing element 34 and is attached to a side of the counter bearing element 34 facing the bearing element 32. The ceramic element 36 has a conical contact surface 38 which, in the final assembly state, bears against a complementary conical counter contact surface 39 of the bearing element 32.The conical design of the contact surfaces 38, 39 allows the contacting area to be increased and thus improves the sealing.

[0030] The second axial bearing 40 and the third axial bearing 50 each also have a bearing element 42, 52 and a counter bearing element 44, 54. The bearing elements 42, 52 form the radial bearings 60, 70, which are designed as bearing sleeves 64, 74. The counter bearing elements 44, 54 form the two flap bodies 20, 22, wherein the flap bodies 20, 22 each have an axial contact surface 46, 56 and the bearing sleeves 64, 74 each have an end face 62, 72 corresponding to the respective contact surface 46, 56.

[0031] A spring retaining element 90 is attached to the protruding section of the flap shaft 18, and a spring element 92 is pre-tensioned between the spring retaining element 90 and the flow housing 12. The spring element 92 exerts such a load on the flap shaft 18 that the counter bearing elements of the axial bearings 30, 40, 50 are loaded in the direction of the bearing elements of the axial bearings 30, 40, 50.

[0032] In its new state, the flap device 10 supports the flap shaft 18 axially solely by the first axial bearing 30. During operation, the counter bearing element 34 rests permanently against the bearing element 32 and is pressed against it by the spring element 92. In the new state, the second axial bearing 40 and the third axial bearing 50 do not support the axial bearing of the flap shaft 18, as the counter bearing elements 44 and 54 are axially spaced from the bearing elements 42 and 53. A gap 45 with a width a1 exists between the bearing element 42 and the counter bearing element 44 of the second axial bearing 40, and a gap 55 with a width a2 exists between the bearing element 52 and the counter bearing element 54. The gap width a2 is greater than the gap width a1.

[0033] During operation of the flap device 10, the bearing element 32 and / or the counter bearing element 34 wear at their relative contact surfaces, causing the flap shaft 18 and thus the counter bearing elements 44, 54 to displace axially by the amount of wear. As soon as the amount of wear corresponds to the gap width a1, contact occurs between the bearing element 42 and the counter bearing element 44 of the second axial bearing 40, so that the flap shaft 18 is additionally axially supported by the second axial bearing 40. During the subsequent operation of the flap device 10, the bearing elements 32, 42 and / or the counter bearing elements 44, 54 of the first axial bearing 30 and the second axial bearing 40 wear down. As soon as the amount of wear corresponds to the gap width a2, the bearing element 52 and the counter bearing element 54 also come into contact, so that the flap shaft 18 is axially supported not only by the first and second axial bearings 30, 40, but also by the third axial bearing 50.

[0034] In this way, the wear-related displacement of the flap shaft 18 over its service life can be reduced, which reliably ensures that the flow cross-sections of the flow channels 14, 16 can be completely closed and that jamming of the flap bodies 20, 22 during adjustment can be reliably prevented.

[0035] It should be clear that the scope of protection of the main claim is not limited to the described embodiment, but that various modifications are possible.

Claims

1. A flap device for an internal combustion engine, having a flow housing (12), which delimits at least one flow duct (14, 16), a flap shaft (18), which is mounted radially and axially on the flow housing (12), and at least one flap body (20, 22) which is mounted on the flap shaft (18) and is arranged in the flow duct (14, 16), wherein the flap body (20, 22) is rotatable together with the flap shaft (18) about a longitudinal axis (24) of the flap shaft (18) between different positions, wherein the flap shaft (18) is mounted axially on the flow housing (12) via a first axial bearing (30) and a second axial bearing (40), wherein the two axial bearings (30, 40) each have a bearing element (32, 42), which is provided on the flow housing (12), and a counter-bearing (34, 44), which is provided on the flap shaft (18), and wherein the first axial bearing (30) and the second axial bearing (40) are designed in such a manner that the counter-bearing element (34) and the bearing element (32) of the first axial bearing (30) permanently lie axially against each other, and the counter-bearing element (44) and the bearing element (42) of the second axial bearing (40) are first of all spaced apart axially from each other and lie axially against each other only in the event of advanced wear of the bearing element (32) and / or of the counter-bearing element (34) of the first axial bearing (30) and an axial shifting of the flap shaft (18) and of the counter-bearing element (44) of the second axial bearing (40) caused by the wear of the first axial bearing (30).

2. The flap device according to Claim 1, characterized in that a radial bearing (60) is provided for the radial bearing of the flap shaft (18), which forms the bearing element (42) of the second axial bearing (40), wherein a face side (62) of the radial bearing (60) interacts with an axial contact surface (46) of the counter-bearing element (44) of the second axial bearing (40).

3. The flap device according to Claim 2, characterized in that the radial bearing (60) is designed as a sliding bearing and comprises a bearing sleeve (64), wherein the bearing sleeve (64) is securely arranged on the flow housing (12).

4. The flap device according to one of the preceding claims, characterized in that the flap body (20) forms the counter-bearing element (44) of the second axial bearing (40), wherein the flap body (20) has the contact surface (46) axially facing the bearing element (42) of the second axial bearing (40).

5. The flap device according to one of the preceding claims, characterized in that the counter-bearing element (34) has a ceramic element (36) on a side facing the bearing element (32).

6. The flap device according to Claim 5, characterized in that the ceramic element (36) has a conical contact surface (38), which lies against a conical counter-contact surface (39) provided on the bearing element (32).

7. The flap device according to one of the preceding claims, characterized in that a first flap body (20) and a second flap body (22) are fastened to the flap shaft (18), wherein the first flap body (20) is arranged in a first flow duct (14) delimited by the flow housing (12), and the second flap body (22) is arranged in a second flow duct (16) delimited by the flow housing (12), wherein a third axial bearing (50) is provided, which is designed in such a manner that a counter-bearing element (54) and a bearing element (52) of the third axial bearing (50) are first of all spaced apart from each other and lie axially against each other only in the event of advanced wear of the bearing elements (32, 42) and / or of the counter-bearing element (34, 44) of the first axial bearing (30) and of the second axial bearing (40) and an axial shifting of the flap shaft (18) and of the counter-bearing element (54) of the third axial bearing (50) caused by the wear.

8. The flap device according to Claim 7, characterized in that a second radial bearing (70) is provided, wherein the second radial bearing (70) forms the bearing element (52) of the third axial bearing (50), and the second flap body (22) forms the counter-bearing element (54) of the third axial bearing (50), wherein an axial contact surface (56) of the second flap body (22) interacts with an axial contact surface (72) of the second radial bearing (70) facing the second flap body (22).

9. The flap device according to Claim 8, characterized in that a third radial bearing (80) is provided, wherein the first flap body (20) is arranged axially between the first radial bearing (60) and the second radial bearing (70), and the second flap body (22) is arranged axially between the second radial bearing (70) and the third radial bearing (80).

10. The flap device according to one of the preceding claims, characterized in that a spring receiving element (90) is fastened at an end of the flap shaft (18) projecting out from the flow housing (12), wherein between the spring receiving element (90) and the flow housing (12) a spring element (92) is arranged in a pre-stressed manner in such a manner that the counter-bearing elements (34, 44, 54) are loaded axially in the direction of the bearing elements (32, 42, 52) of the axial bearings (30, 40, 50).

11. The flap device according to one of the preceding claims, characterized in that the flow duct (14, 16) is an exhaust gas flow duct.