Adjustment device for an exhaust gas turbocharger and exhaust gas turbocharger

Abstract

Control device for an exhaust gas turbocharger, with a flow-through exhaust gas guide section, which has a bypass channel for bypassing a turbine wheel rotatably arranged in the exhaust gas guide section, and with an adjusting arm (3) for receiving a valve element (2), which is provided for opening or closing a flow cross-section of the bypass channel, wherein the adjusting arm (3) is movably received in the exhaust gas guide section, and wherein a spring element (14) is provided on the adjusting arm (3) at least for securing the position of the valve element (2), wherein the spring element (14) is formed radially and axially held by the valve element (2), the valve element (2) has a first section (19) and a second section (20), and a groove (21) is formed between the first section (19) and the second section (20), characterized in that the groove (21) is arranged such thatthat a first bearing surface (15) of the spring element (14) is in contact with the second section (20).,

Description

The invention relates to an adjusting device for an exhaust gas turbocharger of the type specified in the preamble of patent claim 1.JP 2015-197 068 A and DE 10 2010 043 147 A1 each disclose an exhaust gas turbocharger according to the preamble of patent claim 1.The laid-open specification DE 10 2012 101 322 A1 discloses an adjusting device for an exhaust gas turbocharger having a turbine, wherein the turbine has an exhaust gas guide section through which flow can pass and a bypass duct which serves to bypass an exhaust gas flow of a turbine wheel arranged in the exhaust gas guide section. The adjusting device comprises a valve element for closing the bypass channel, and an adjusting arm which receives the valve element. This adjusting arm is rotatably mounted in the exhaust gas guide section. The valve element is secured in position on the adjusting arm with the aid of a spring element in order to avoid noises and to optimize wear or reduce wear during operation of the exhaust gas turbocharger.It is problematic that, due to the operation of the exhaust gas turbocharger, in particular in conjunction with the exhaust gas turbocharger with an internal combustion engine, the exhaust gas turbocharger is exposed to temperature fluctuations and body oscillations. The temperature fluctuations lead to a constant heating and cooling of the individual components of the exhaust gas turbocharger, wherein the greatest temperature fluctuations are present, in particular in the region of the turbine of the exhaust gas turbocharger, on account of the combustion product of the internal combustion engine flowing through the exhaust gas guide section. The closer a component of the exhaust gas turbocharger is thus arranged to a duct of the exhaust gas guide section having the combustion product flowing through, the higher is a probability of failure of this component. This is because the constantly repeated temperature changes lead to a constant change in the expansion of the components, as a result of which loosening, stresses or material fatigue can occur. Since the movable connection is formed by means of the securing element exerting compressive stress, thus comprising the adjusting members to be connected, an outer side of the securing element is positioned close to the channel having the combustion product and is consequently subject to the aforementioned temperature fluctuations.The spring element serves to secure the position of the valve element in any position. In a closed position, the flow cross section can be closed without leaks with the aid of the valve element, so that no losses in efficiency of the exhaust gas turbocharger occur. In an open position of the valve element, in which it partially or completely releases the flow cross section, the valve element can be excited to oscillations due to the exhaust gas flow in the bypass channel. This too is to be avoided since they can bring about rattling noises.The object of the present invention is to provide an improved control device for an exhaust gas turbocharger. A further object of the invention is to provide an improved exhaust gas turbocharger.This object is achieved by an adjusting device for an exhaust gas turbocharger having the features of patent claim 1. The further object is achieved with an exhaust gas turbocharger having the features of patent claim 7. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.The control device according to the invention for an exhaust gas turbocharger has a valve element which is accommodated on an adjusting arm of the control device. The valve element is arranged in a bypass channel of the exhaust gas guide section in an exhaust gas guide section of the exhaust gas turbocharger through which flow can pass and serves for opening or closing a flow cross section of the bypass channel. With the aid of the bypass duct, it is possible to bypass a turbine wheel which is rotatably arranged in the exhaust gas guide section and through which the entire exhaust gas quantity flowing through the exhaust gas guide section flows when the flow cross section is closed. The adjusting arm is movably accommodated in the exhaust gas guide portion. For securing the position of the valve element, a spring element is provided on the adjusting arm. According to the invention, the spring element is formed radially and axially held by the valve element, the valve element has a first section and a second section, a groove is formed between the first section and the second section, and the groove is arranged such that a first bearing surface of the spring element is in contact with the second section.Spring elements according to the prior art are usually movable in an axial direction along a valve longitudinal axis. In other words, they may be compressed to reduce their axial expansion or relaxed to increase their axial expansion. This takes place as a function of the forces acting on the valve element. To avoid rattling noises, the position securing of the valve element is effected by a force exerted by the spring element on the valve element. In order that the spring element can exert its force on the valve element, the spring element is positioned between the adjusting arm and a cover element provided for securing the valve element.In order to reduce component costs of the control device, the spring element is held radially and axially by the valve element according to the invention. This eliminates the cover element and the component costs are reduced. A further advantage is the avoidance of rattle noises occurring when the bypass channel is closed.Advantageously, the spring element is formed on a pin of the valve element in a form-fitting manner therewith. Thus, a simple accommodation possibility of the spring element is provided, since the pin serves for a connection of the valve element to the adjusting arm.Advantageously, the spring element is arranged in a form-fitting manner between the first section of the valve element and the second section of the valve element. This makes it possible to clamp the spring element in the valve element. This is particularly preferably brought about with the aid of a riveting method, wherein the spring element is held in a form-fitting manner between the first section and the second section.In a further embodiment, the spring element is arranged on the valve element with the aid of a hold-down device. The hold-down device serves for simplified assembly in that the spring element can be held down before the riveting process. The outer diameter of the spring element does not abut on the cover element compared to the prior art, whereby the outer diameter of the spring element itself is not limited by the outer diameter of the cover element and can be designed in an optimized manner. Further advantages of the hold-down device are an avoidance of folding over of the spring element, the absorption of loads occurring during the riveting process and thus relief of the spring element, which is thereby less deformed. It is likewise advantageous to use the hold-down device if a weld is used instead of riveting, since the heat input into the spring element is lower when a hold-down device is used.In a further embodiment, the holding-down device has a further outer diameter which is smaller than an outer diameter of the spring element. As a result, the movability of the valve element is not limited by the hold-down device.In a further embodiment, a second bearing surface of the spring element, which bearing surface has a smaller diameter than an outer edge of the spring element, has a contact with the adjustment arm, wherein a distance is formed between the outer edge and the adjustment arm. This provides the possibility of a radial sliding of the spring element on the adjusting arm, so that tilting movements caused by the decentralized load can be compensated within the system consisting of the valve element and the adjusting arm without causing additional wear due to the relative movements at the contact positions of the sliding partners. This leads to a further increased service life of the control device.The second aspect of the invention relates to an exhaust gas turbocharger which has an exhaust gas guide section through which a flow can pass, with a bypass duct for bypassing a turbine wheel which is rotatably arranged in the exhaust gas guide section, and with a regulating device for opening and closing a flow cross section of the bypass duct, wherein the regulating device is designed according to one of Claims 1 to 6. An exhaust gas turbocharger is thus provided which, in addition to an increased service life, also has a rapid response behavior of the control device.Further advantages, features and details of the invention are evident from the following description of preferred exemplary embodiments and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or alone.The drawing shows in: FIG. 1 shows a perspective view of a control device of an exhaust gas turbocharger according to the prior art, FIG. 2 is a perspective sectional view of the control device according to the invention. FIG. 1, FIG. 3 is a detail of a longitudinal section of the control device according to the invention. FIG. 1, FIG. 4 shows a perspective view of a control device according to the invention in a first exemplary embodiment of an exhaust gas turbocharger according to the invention, and FIG. 5 shows a perspective sectional view of the control device according to the invention. FIG. 4, and FIG. 6 shows a detail of a longitudinal section of the control device according to. FIG. 4, FIG. 7 shows a perspective view of the regulating device according to the invention in a second exemplary embodiment, FIG. 8 is a perspective sectional view of the control device according to the invention. FIG. 7, and FIG. 9 is a detail of a longitudinal section of the control device according to the invention. FIG. 8 shows a schematic view of the embodiment of the invention.A control device 1 of an exhaust gas turbocharger according to the prior art, not shown in more detail, is designed as shown in FIG. 1. The exhaust gas turbocharger has an exhaust gas guide section, which can be flown through, not shown in detail, and through which a fluid, as a rule exhaust gas, flows during operation of the exhaust gas turbocharger. The exhaust gas is generally a combustion product of an internal combustion engine, not shown in detail. Such control devices are also known by the term wastegate device.The exhaust gas turbocharger is assigned an air guide section, not shown in more detail, through which flow can pass, and a bearing section, not shown in more detail, positioned between the exhaust gas guide section and the air guide section, wherein a rotor, not shown in more detail, is rotatably accommodated in the bearing section. The rotor has a compressor wheel, not shown in detail, and a turbine wheel, not shown in detail, which are connected to one another in a rotationally fixed manner by means of a shaft, not shown in detail. The compressor wheel is accommodated in a first wheel chamber, not shown in detail, of the air guide section for intake of generally fresh air, and the turbine wheel is accommodated rotatably in a second wheel chamber, not shown in detail, of the exhaust gas guide section. During operation of the exhaust gas turbocharger, the turbine wheel is acted upon and driven by the exhaust gas flowing through the exhaust gas guide section, wherein it can execute a rotational movement. This rotational movement can be transmitted by means of the shaft to the compressor wheel, which can thus execute a rotational movement simultaneously with the rotational movement of the turbine wheel. With the aid of the compressor wheel and its rotational movement, fresh air is drawn in, which is compressed in the air guidance section.The exhaust gas turbocharger is designed as a so-called wastegate supercharger, that is to say it has the regulating device 1 for completely or partially bypassing the turbine wheel with the aid of a bypass duct which is formed in the exhaust gas guide section and is not illustrated in any more detail. This control device 1, which serves for controlling a flow cross section of the bypass channel, which is not shown in detail, has a valve element 2 which is designed such that it can be closed and opened, preferably in the form of a flap, generally referred to as a waste gate flap or waste gate valve, and an adjusting device, which is not shown in detail, for actuating this valve element 2.The valve element 2, having a valve element longitudinal axis 25, is arranged on an adjustment arm 3 of the adjustment device. The adjusting arm 3 has, at its end 5 which is embodied remote from an adjusting shaft 4 of the adjusting arm 3, a fork-shaped receiving opening 6 for receiving a securing pin 7.The securing pin 7 serves to prevent rotation of the valve element 2, which is accommodated in a further receiving opening 8 of the adjusting arm 3 by means of a pin- or bolt-shaped pin 9. The pin 9 and the securing pin 7 are configured on a first valve surface 10 configured facing the adjusting arm 3. A second valve surface 11 of the valve element 2 formed facing away from the first valve surface 10 is positioned facing the flow cross section to be regulated.The valve element 2 is fixed to the adjusting arm 3 with the aid of a cover plate 12. The pin 9 projects through the further receiving opening 8 and into the cover disk 12. At its journal end 13 facing away from the second valve surface 11, it is connected rivet-like to the adjusting arm 3 with the aid of the cover disk 12. It can also be welded or welded and riveted or soldered, pressed or bonded.A spring element 14 for clamping the valve element 2 is arranged between the adjusting arm 3 and the cover plate 12, whereby rattle noises during a movement of the valve element 2 are reduced. Furthermore, this spring element 14 serves for compensating play, in particular also for compensating play on account of a high temperature change during operation of the exhaust gas turbocharger. In particular, the wear between the adjustment arm 3, the valve element 2 and the spring element 14 is reduced or avoided. The wear of the valve element 2 is dependent on its installation position and the force of gravity and is eliminated with the aid of the spring element 14.The spring element 14 is designed in the form of a disk spring and has an inner diameter DI and an outer diameter DA. In the region of the inner diameter DI, a first support surface 15 is formed, which is configured to be planar with the adjusting arm 3. In other words, the first bearing surface 15 lies flat on the adjusting arm 3. In the region of the outer diameter DA, a second bearing surface 16 is formed, which is likewise configured to be planar with the cover disk 12. In other words, the second bearing surface 16 is supported flat on the cover pane 12.FIGS. 4 to 6 show a control device 1 according to the invention in a first exemplary embodiment. The control device 1 according to the invention has the spring element 14, which is designed such that it is held radially and axially by the valve element 2.As is shown in particular in FIG. 6, the spring element 14 is received in a form-fitting manner between a first section 19 and a second section 20 of the valve element 2. The first section 19 and the second section 20 have different diameters before the spring element 14 is assembled, so that the spring element 14 can be received by the first section 19 surrounding the latter. The spring element 14 is riveted to the valve element 2 with the aid of a riveting process, wherein the pin 9 is designed as a rivet. Due to the riveting process, the spring element 14 is clamped between the first section 19 and the second section 20, wherein a form-fit receptacle is formed between the two sections 19, 20. After the riveting process, the spring element 14 is firmly connected to the valve element 2. Between the first section 19 and the second section 20 a groove 21 is formed after the riveting process, in which the spring element 14 is positioned.The spring element 14 has the first bearing surface 15 in the region of its inner diameter DI. In the region of its outer periphery 22 with its outer diameter DA, the spring element 14 is formed in a curved manner, wherein a spring element radius RF is formed on the outer diameter DA. The spring element radius RF could likewise be so small that the spring element 14 is configured to be bent in the region of the second bearing surface 16.With the aid of the spring element radius RF, the second contact surface 16 is formed quasi linearly, since an outer edge 23 of the spring element 14 does not contact the adjustment arm 3 and a distance A is formed between the outer edge 23 and the adjustment arm 3. In other words, this means that it is designed to be very small in comparison with the second bearing surface 16 of the prior art, so that a high contact pressure force can be realized for stabilizing the valve element 2. Furthermore, due to the small second bearing surface 16, a low static friction is applied, so that a tilting movement of the valve element 2 about a tilting point 18 is quickly compensated for and only low actuating forces are to be applied by the actuator.FIGS. 7 to 9 show the regulating device according to the invention in a second exemplary embodiment. For simplified assembly, a disk-shaped holding-down device 24 is accommodated in the groove 21 in the region of the first bearing surface 15. The holding-down device 24 has a further outer diameter DA 2, which is smaller than the outer diameter DA of the spring element 14, as a result of which the second bearing surface 16 does not lie opposite a movement-preventing stop during a positioning process of the valve element 2.

Claims

Control device for an exhaust gas turbocharger, having an exhaust gas guide section through which flow can pass, which has a bypass duct for bypassing a turbine wheel which is arranged rotatably in the exhaust gas guide section, and having an adjusting arm (3) for receiving a valve element (2) which is provided for opening or closing a flow cross section of the bypass duct, wherein the adjusting arm (3) is received movably in the exhaust gas guide section, and wherein a spring element (14) is provided at least for securing the position of the valve element (2) on the adjusting arm (3), wherein the spring element (14) is formed so as to be held radially and axially by the valve element (2), the valve element (2) has a first section (19) and a second section (20), and a groove (21) is formed between the first section (19) and the second section (20), characterized in that the groove (21) is arranged in such a way, a first bearing surface (15) of the spring element (14) is in contact with the second section (20).Control device according to claim 1, characterised in that the spring element (14) is formed on a pin (9) of the valve element (2) in a form-fitting manner therewith.Control device according to claim 1 or 2, characterised in that the spring element (14) is arranged in a form-fitting manner between the first section (19) of the valve element (2) and the second section (20) of the valve element (2).Control device according to one of the preceding claims, characterized in that the spring element (14) is arranged on the valve element (2) with the aid of a hold-down device (24).Regulating device according to Claim 4, characterized in that the holding-down device (24) has a further outer diameter (DA2) which is smaller than an outer diameter (DA) of the spring element (14).Control device according to one of the preceding claims, characterized in that a second bearing surface (16) of the spring element (14), which bearing surface has a smaller diameter than an outer edge (23) of the spring element (14), has contact with the adjusting arm (3) and wherein a distance (A) is formed between the outer edge (23) and the adjusting arm (3).Exhaust gas turbocharger, having an exhaust gas guide section through which flow can pass, which has a bypass duct for bypassing a turbine wheel which is arranged rotatably in the exhaust gas guide section, and having a regulating device (1) for opening and closing a flow cross section of the bypass duct, characterized in that the regulating device (1) is designed according to one of Claims 1 to 6.

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