Spur gear for a transmission shaft, transmission shaft, transmission and motor vehicle

Abstract

The invention relates to a spur gear (1), a transmission shaft (2), a transmission, and a motor vehicle. Two gear ring bodies (7, 8), each with rotationally fixed helical gear rings (9a, 9b), are axially clamped together by means of a connecting device (10) of the spur gear (1), the helical gear rings (9a, 9b) forming a double helical gear (9) of the spur gear (1). Furthermore, the gear ring bodies (7, 8) define a coupling chamber (13) in which a frictionally engaging overload protection clutch (22) of the spur gear (1) is formed by two interlocking clutch disc assemblies (15, 19), by means of which the gear ring bodies (7, 8) and the hub connecting element (21) are rotationally coupled to one another for the transmission of a torque up to a predetermined torque limit.

Description

The present invention relates to a spur gear for a transmission shaft. Furthermore, the invention relates to a transmission shaft which has such a spur gear. The invention also relates to a transmission which has the spur gear or the transmission shaft, and to a motor vehicle which has the spur gear, the transmission shaft or the transmission.Transmissions, in particular for motor vehicles, are nowadays designed on the basis of sometimes very high overload factors which result from peak torques which occur only during special events. This means that the conventional transmissions are designed to be so strong or stable and consequently to be mass-rich that they do not suffer any damage even when said peak torques occur. The increased mass of such conventional transmissions due to the stability requirement, however, does not provide any advantage during a major part of the useful life of the transmission, since-as already explained-the special events occur only particularly rarely. Thus, these conventional transmissions are in the way of developing particularly light motor vehicles which can be operated particularly energy-efficient or fuel-efficient and / or low-emissions.U.S. Pat. No. 10,683,920 B2 proposes a transmission for an electrically drivable motor vehicle, which has a planetary transmission, the ring gear of which is mounted in the transmission housing by means of an overload clutch. Furthermore, DE 10 2020 101 349 A1 discloses a gear slip clutch with a gear which is rotatably mounted on a first drive flange and can be frictionally braced with the drive flange via a friction element arranged on a drive flange surface and via a pretensioning unit. However, these conventional solutions are particularly complicated and require a particularly large amount of installation space, which is nowadays limited by packaging requirements.It is an object of the present invention to develop a particularly compact and efficient protective device for a motor vehicle transmission.This object is achieved by the subject matters of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description and the figures. Features, advantages and possible configurations which are set forth in the context of the description for one of the subjects of the independent claims are to be regarded, at least analogously, across all categories and embodiments as features, advantages and possible configurations of the respective subject of the other independent claims and of each possible combination of the subjects of the independent claims, optionally in conjunction with one or more of the dependent claims.According to the invention, a spur gear for a transmission shaft, a transmission shaft having the spur gear, a transmission having the transmission shaft, and a motor vehicle having the transmission are proposed. In the intended installation position, a component of the transmission shaft is formed by the spur gear, the shaft main body of which is designed as a hollow shaft in a possible development. Furthermore, the transmission shaft forms a component of the transmission in its intended installation position. The transmission in turn forms a component of the motor vehicle in its intended installation position, so that the motor vehicle has the transmission shaft and consequently the spur gear. The motor vehicle is in particular a purely or hybrid-electrically drivable motor vehicle which has the transmission with the transmission shaft or the spur gear. In this respect, the spur gear is configured, for example, to transmit a torque in a drive train of the motor vehicle. In order to avoid torque-induced damage to the spur gear and / or to the transmission shaft and consequently to the transmission, the spur gear has a protection device in the form of an overload protection clutch, by means of which the torque transmission is interrupted if the torque is greater than a predefined torque limit value. However, the use of the spur gear, the transmission shaft and the transmission is not limited to the technical field of motor vehicles.The spur gear has a first toothed ring body and a second toothed ring body. A first helical gear is fixedly attached to the first gear ring body-that is to say both rotationally fixed and non-displaceably-and a second helical gear ring is fixedly attached to the second gear ring body. The two gear ring bodies are made separately from each other, and the two helical gears have opposite helical angles. Thus, if the first helical gear has a leftward-increasing skew angle, the second helical gear has a rightward-increasing skew angle and vice versa. The respective toothed ring body and the corresponding associated helical toothed ring can be connected to one another in a force-fitting, form-fitting and / or materially integral manner. One or both of the toothed rim bodies and the correspondingly associated helical toothed rim can be connected to one another in a force-fitting and / or form-fitting manner, are in any case fixedly fastened to one another. For this purpose, it is conceivable for the toothed rim body and the associated helical toothed rim to be produced separately from one another and then to be fastened to one another or connected or joined to one another. In a possible refinement of the spur gear, the toothed ring body and the associated helical toothed ring are connected to one another in a materially integral manner, in particular formed or formed integrally with one another. This ensures a particularly stable and reliable connection between the toothed rim body and the helical toothed rim.By means of a connecting device of the spur gear, the toothed ring bodies are fastened to one another in a rotationally fixed manner and are axially clamped to one another. For example, the connecting device has a screw arrangement with one screw or more screws and correspondingly many internal threaded holes which are formed in one of the toothed rim bodies or are divided onto the toothed rim bodies. By the respective screw extending through one of the sprocket bodies, wherein a threaded connection is provided between an external thread of the screw and the internal thread of the corresponding internal threaded hole of the other of the sprocket bodies, the two sprocket bodies are axially-i.e. along a spur wheel longitudinal central axis of the spur wheel-clamped to one another. The toothed ring bodies which are clamped to one another delimit with one another or between one another a coupling chamber of the spur wheel. The clutch chamber is thus defined on the one hand by the first toothed ring body and on the other hand by the second toothed ring body. For example, for this purpose the respective helical gear ring has a greater axial extension length than a respective radial wall element of the corresponding gear ring body. Since the helical gear rings have the same root circle, pitch circle and tip circle diameter as well as the same tooth geometry and the same axial extension length and are arranged together along the spur gear longitudinal center axis, the helical gear rings together form a double helical toothing or arrow toothing of the spur gear. The double helical toothing of the spur gear permits a drive free of axial force, since the axial forces of the two helical gear rings cancel one another out due to the opposite pitch or due to the oppositely oriented helix angles. Thus, when the spur gear meshes rollingly with another appropriately toothed spur gear, axial forces occurring lift each other, whereby a bearing of the spur gear or of the transmission shaft is loaded particularly little, in particular is loaded only in the radial direction. This advantageously leads to particularly low losses of bearing friction. Due to the multi-part construction of the spur gear, its double bevel or arrow toothing can be produced particularly easily.In the clutch chamber, the spur gear further has a clutch disk carrier which is connected to one or both of the ring gear bodies in a rotationally fixed manner and to which a first clutch disk arrangement is fastened in a rotationally fixed manner. The clutch disk carrier is at any rate rotationally fixed with respect to the double helical toothing of the spur gear. In addition, the spur gear has in its clutch chamber a second clutch disk arrangement which has a hub connecting element which is configured to be connected to the transmission shaft in a rotationally fixed manner. The two clutch disk arrangements engage with one another, for example by a first clutch disk of the first clutch disk arrangement and a second clutch disk of the second clutch disk arrangement being arranged alternately in the axial direction. If three clutch plates are considered which are successive in the axial direction, two first clutch plates are spaced apart from one another via a second clutch plate and / or two second clutch plates are spaced apart from one another via a first clutch plate. In this case, two clutch disks which are directly successive in the axial direction bear directly against one another. The respective clutch disk is in particular designed as a respective clutch ring disk.The two clutch disk arrangements form in the clutch chamber an overload protection clutch acting in a frictional manner, by means of which the ring gear bodies or the double helical toothing and the hub connecting element are coupled to one another in a rotationally fixed manner for the transmission of a torque up to a predefined torque limit value. Thus, the overload protection clutch prevents rotation between the first and second clutch disk assemblies and, consequently, between the gear ring bodies or the double helical gearing and the hub connecting element, except in such an operating state of the spur gear, the transmission shaft or the transmission in which the torque to be transmitted is greater than a clutch torque prevailing between the clutch disks.The overload protection clutch located in the clutch chamber, i.e. integrated into the spur gear, prevents torque-induced damage to the spur gear which has the first and the second ring gear body and / or to a further spur gear which meshes with the double bevel or arrow toothing of the spur gear. The torque transmission is advantageously limited to a maximum permissible value, namely the predefined torque limit value, so that a transmission having the spur gear does not have to be specifically designed to be able to absorb torque peaks without damage. Instead, a new transmission can be designed or designed on the basis of the maximum transmittable torque, i.e. on the basis of the predefined torque limit value, which overall leads to a particularly light transmission and consequently to a particularly light motor vehicle. By arranging the overload protection coupling within the coupling chamber, which can be sealed off from the environment of the spur gear in the intended installation position of the spur gear, the overload protection coupling can be protected from contact with undesired material, for example chips or other foreign bodies or dirt. Thus, a particularly reliable operation of the overload protection clutch is possible.The transmission shaft, the shaft main body of which is optionally designed as a hollow shaft, has on its outer circumferential surface a shaft connecting element which corresponds to the hub connecting element for establishing a rotationally fixed connection. In the intended installation position of the spur gear on / on the transmission shaft, the hub connecting element and the shaft connecting element provide a connection that is fixed against relative rotation, so that the transmission shaft and the second clutch disk arrangement of the spur gear are connected to one another in a fixed against relative rotation.If the shaft main body of the transmission shaft is designed as a hollow shaft, a possible refinement of the transmission shaft provides that it has a shaft through-opening or more shaft through-openings, wherein the respective shaft through-opening opens, on the one hand, into a hollow shaft interior of the transmission shaft and, on the other hand, on or in the shaft connecting element of the transmission shaft and, as a result, into the clutch chamber. The respective shaft through-opening functions as a lubricant supply channel for the overload protection clutch. During operation of the transmission shaft or of the transmission having the transmission shaft, a lubricant, for example an oil, is introduced into the hollow shaft interior of the transmission shaft, which lubricant flows through the shaft passage opening(s) and into the clutch chamber as a result of centrifugal force. This ensures that a coefficient of friction prevailing between the clutch disks lying directly against one another remains constant during operation of the transmission shaft.According to a further possible embodiment of the spur gear, one or both of the ring gear bodies has / have an axial ring gear body through-opening which opens on the one hand into the clutch chamber and on the other hand on an outer wall of the corresponding ring gear body. Two or more such sprocket body through openings are conceivable. The respective sprocket body through-opening functions as a lubricant outlet channel for the overload protection clutch. Lubricant introduced into the clutch chamber during operation of the transmission shaft may flow through the sprocket body passage opening(s) and out of the clutch chamber. As a result, the spur gear or its overload protection clutch can be integrated particularly efficiently into a lubricant circuit.According to a further possible embodiment, the spur gear has a clutch spring unit which is supported on a first clutch chamber inner wall of the clutch chamber, wherein the overload protection clutch is clamped between the clutch spring unit and a second clutch chamber inner wall of the clutch chamber which is axially opposite the first clutch chamber inner wall. By means of the clutch spring unit, the clutch plates of the clutch plate arrangements are thus axially clamped to one another. The clutch spring unit has in particular a disk spring or more disk springs and / or a coil spring or more coil springs. Due to the clutch spring unit, the clutch plates of the clutch plate arrangements are particularly reliably clamped to one another, wherein a clamping force of the clutch spring unit substantially determines the predefined torque limit value. This means that the torque limit value, which is to be transmitted to the maximum by means of the spur gear having the double helical toothing, can be realized by a corresponding design of the clutch spring unit.According to a further possible embodiment, the spur gear has a tolerance compensation disc which is arranged between the first toothed ring body and the second toothed ring body, wherein an axial thickness or thickness of the tolerance compensation disc is formed such that the clutch discs are clamped to one another with a predetermined clamping force when the toothed ring bodies are axially clamped to one another by means of the connecting device. Two or more partial disks of different or identical thickness can be stacked to form the tolerance compensation disk. By using the tolerance compensation disk, manufacturing tolerances of the sprocket bodies can be compensated, so that the sprocket bodies that are clamped to one another are not subject to bending stress in an undesired manner. A desired axial distance between the toothed ring bodies can be set during the assembly of the toothed ring bodies by means of the correspondingly dimensioned tolerance compensation disc.According to a further possible embodiment, the second clutch chamber inner wall has a support collar which projects axially into the clutch chamber and is arranged radially centrally between the clutch disk carrier and the hub connecting element. The overload protection coupling is then axially supported on the support collar. In addition, the clutch spring unit bears radially centrally between the clutch disk carrier and the hub connecting element on the overload protection clutch. Thus, the overload protection clutch is advantageously clamped at its effective diameter between the first and the second ring gear body.In another possible embodiment, the spur gear comprises a straight alignment pin. This is seated on the one hand in a form-fitting manner in a first axial alignment pin receptacle of the first toothed ring body and on the other hand in a form-fitting manner in a second axial alignment pin receptacle of the second toothed ring body. By means of the alignment pin, the toothed rim bodies and consequently the helical toothed rims are rotationally aligned with one another. In particular, the alignment pin receptacles and the alignment pin are arranged radially on the outside, preferably between the helical gears and the clutch disk carrier, so that the rotational alignment of the gear ring bodies with respect to one another takes place close to the helical gears. Optionally, it can be provided that the spur gear has two or more such alignment pins and consequently correspondingly many alignment pin receptacles. The alignment pin does not participate in the axial clamping together of the toothed ring bodies, but merely blocks a rotation of the toothed ring bodies relative to one another with respect to the spur wheel longitudinal central axis. Alternatively, the connecting means may comprise the alignment pin or pins, in particular one or more of the screws may / may function as the alignment pin and / or comprise an alignment means, such as an alignment cone portion. In such a case, the corresponding sprocket body then has a matching alignment means seat. When the toothed ring bodies are axially clamped together, they are then aligned rotationally with one another. Due to the alignment pin, the toothed ring bodies can be aligned particularly efficiently on one another, as a result of which the helical toothed rings can be combined particularly efficiently to form double helical gearing.A further possible embodiment of the spur gear provides that the hub connecting element has a hub spline which is configured to be connected in a rotationally fixed manner to a corresponding hub spline of the shaft connecting element of the transmission shaft. Thus, for the transmission shaft according to the invention, the case applies in which the second clutch disk arrangement and the shaft main body are connected to one another in a rotationally fixed manner in that the hub splines engage one another. Thus, a torque transmission between the transmission shaft and the double helical toothing of the spur gear is ensured. In addition, such a splined connection between the shaft main body and the second clutch disk arrangement is appropriate in order to be able to mount the overload protection clutch and consequently the spur gear particularly easily on the transmission shaft. Alternatively or additionally to this spline connection, it can be provided that the hub connecting element and the shaft connecting element are connected to one another in a force-fit and / or firmly bonded manner.In a further possible embodiment of the spur gear, it is provided that the clutch disk carrier has a carrier spline toothing, and the first clutch disk arrangement has a corresponding clutch spline toothing, wherein the clutch disk carrier and the first clutch disk arrangement are fixed to one another in a rotationally fixed manner by the carrier spline toothing and the clutch spline toothing engaging one another. In this way, the overload protection clutch can be installed in the clutch chamber in a particularly simple manner. Alternatively or additionally to this splined connection between the first clutch disk arrangement and the corresponding ring gear body, it can be provided that the hub connecting element and the shaft connecting element are connected to one another in a force-fit and / or firmly bonded manner.In a further possible embodiment of the spur gear, it is provided that a radial wall element of the respective ring gear body is designed as a radial support element, by means of which the spur gear can be radially supported on the transmission shaft. One of the clutch chamber inner walls is formed by the respective radial wall element. In particular, the radial support elements, i.e. the radial wall elements or the toothed rim bodies, are designed such that, in the intended installation position of the spur gear, a clearance or transition fit results between the latter and the shaft main body. This means that, without the overload protection clutch, the spur gear would be rotatable with respect to the shaft main body already at a particularly low torque, at the latest before the predetermined torque limit value is reached. In this respect, the toothed ring bodies are designed with regard to their stability in such a way that they mainly transmit a radial force and are at most used for the transmission of the torque between the shaft main body and the spur gear or the double-bevel toothing thereof. By omitting a rotationally fixed connection between the toothed ring body and the shaft main body, the spur gear can be mounted on the shaft main body in a particularly simple manner.In a possible development, the spur gear is designed as an externally toothed spur gear or as an internally toothed spur gear (ring gear). In other words, the double helical toothing is formed as an external toothing or as an internal toothing. Thus, different types of gear can be produced, including epicyclic gears which are protected against damage due to excessive torque input due to the spur gear.Further features of the invention can be derived from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description and the features and combinations of features shown below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The drawing shows in the single FIGURE (FIG. 1 ) a schematic and sectional view of a spur gear which is mounted on a transmission shaft and has a double helical toothing and an overload protection clutch. The following description relates to the spur gear 1, the transmission shaft 2 having the spur gear 1, a transmission having the transmission shaft 2, and a motor vehicle having the transmission. In the figure, identical and functionally identical elements are provided with the same reference numerals. The transmission and motor vehicle are not shown.The spur gear 1 is seated on a shaft main body 3 of the transmission shaft 2, wherein the shaft main body 3 is embodied here as a hollow shaft. Accordingly, the shaft main body 3 has a hollow or material-free hollow shaft interior 4 which extends along a transmission shaft longitudinal central axis 5 of the transmission shaft 2. The transmission shaft longitudinal center axis 5 and a spur gear longitudinal center axis 6 of the spur gear 1 coincide. In the intended installation position, a component of the transmission shaft 2 is thus formed by the spur gear 1. The transmission shaft 2 is a component of the transmission, which is designed in particular as a motor vehicle transmission and which can be, for example, a gear change transmission or a motor vehicle main transmission with invariable transmission ratio or a longitudinal or transverse differential. The motor vehicle which has the transmission with the spur gear 1 or the transmission shaft 2 is in particular a purely or hybrid-electrically drivable motor vehicle.The spur gear 1 has a first toothed ring body 7 and a second toothed ring body 8 produced separately therefrom, wherein the first toothed ring body 7 and a first helical toothed ring 9 aare firmly connected to one another. Further, the second sprocket body 8 and a second helical sprocket 9b are fixedly connected to each other. The helical gear rings 9 a, 9 bhave the same root circle, pitch circle and tip circle diameter and the same tooth geometry and the same axial extension length and are arranged together along the spur gear longitudinal central axis 6. Due to their inclination angles which are identical in terms of amount but opposite in terms of the inclination direction, the helical gear rings 9 a, 9 bform with one another a double helical toothing 9 or arrow toothing of the spur gear 1. Here, in the described example, the connecting device 10 has a screw arrangement with one screw 11 or more screws 11 and correspondingly many internal threaded holes 12 in the second sprocket body 8. The respective screw 11 extends through the first sprocket body 7, a threaded connection being provided between an external thread of the screw 11 and the internal thread of the internal threaded hole 12 of the second sprocket body 8. As a result, the two toothed ring bodies 7, 8 are axially clamped to one another-i.e. along the spur wheel longitudinal central axis 6. The toothed rim bodies 7, 8 which are clamped to one another delimit with one another or between one another a coupling chamber 13 of the spur gear 1.In the interior of the clutch chamber 13, the spur gear 1 has a clutch disk carrier 14, which is connected in a rotationally fixed manner to one or to both of the ring gear bodies 7, 8, in the present case only to the second ring gear body 8. In the present example, the clutch plate carrier 14 and the second ring gear body 8 are formed integrally with one another. A first clutch disk arrangement 15 is fixed in a rotationally fixed manner to the clutch disk carrier 14, which clutch disk arrangement has a multiplicity of first clutch disks 16. The respective first clutch disk 16 is embodied here as a respective clutch ring disk. In the present example, the clutch disk carrier 14 has a carrier spline 17 which corresponds to an outer-circumferential-side clutch spline 18 of the first clutch disk arrangement 15, that is to say to a respective outer-circumferential-side spline of the first clutch disks 16, with the result that a rotationally fixed connection is created between the clutch disk carrier 14 and the first clutch disk arrangement 15 by means of the intermeshing splines 17, 18.In addition, the spur gear 1 has in the clutch chamber 13 a second clutch disk arrangement 19 which engages into the first clutch disk arrangement 15 and has a multiplicity of second clutch disks 20, wherein in the present case the respective second clutch disk 20 is designed as a respective second clutch ring disk. A hub connection member 21 of the second clutch disk assembly 19 is configured to be non-rotatably connected to the shaft main body 3 of the transmission shaft 2. The two clutch disk arrangements 15, 19 which engage one another form an overload protection clutch 22 which acts in a frictional manner in the clutch chamber 13 and by means of which the toothed ring bodies 7, 8 or the double helical toothing 9 and the hub connecting element 21 are coupled to one another in a rotationally fixed manner in order to transmit a torque up to a predefined torque limit value. The clutch disks 16, 20 form a clutch disk stack or a multiplate clutch along the spur gear longitudinal central axis 6, wherein a first clutch disk 16 and a second clutch disk 20 are alternately stacked. During operation of the spur gear 1 or of the transmission shaft 2, the overload protection clutch 22 prevents or blocks a rotation between the first clutch disk arrangement 15 and the second clutch disk arrangement 19 and consequently between the ring gear bodies 7, 8 and the hub connecting element 21, except in such an operating state of the spur gear 1 or of the transmission shaft 2 in which the torque to be transmitted is greater than a clutch torque prevailing between the clutch disks 16, 20.According to the present example, the hub connection member 21 has a spur gear side hub spline 23 configured to be rotationally fixedly connected to a corresponding shaft main body side hub spline 24 of a shaft connection member 25 of the transmission shaft 2. The shaft connecting member 25, which here includes the shaft main body side boss spline 24 in the example, is disposed on an outer circumferential surface 26 of the transmission shaft 2 and the shaft main body 3 thereof, respectively. By the splines 23, 24 being engaged with each other, a non-rotational connection is provided between the second clutch plate assembly 19 and the shaft main body 3. The spur-gear-side hub spline 23 is formed by respective inner-circumferential splines of the second clutch plates 20.In the present case, the spur gear 1 has a clutch spring unit 27 with two or more disk springs 27 a, 27 b. The clutch spring unit 27 is supported on a first clutch chamber inner wall 28 of the clutch chamber 13, wherein the overload protection clutch 22 is clamped between the clutch spring unit 27 and a second clutch chamber inner wall 29 of the clutch chamber 13 axially opposite the first clutch chamber inner wall 28. A clamping force of the clutch spring unit 27 or of the disk springs 27 a, 27 bpredictably determines the predefined torque limit value of the overload protection clutch 22.In addition, a tolerance compensation disk 30 is provided here, which is arranged between the first toothed ring body 7 and the second toothed ring body 8, wherein an axial thickness of the tolerance compensation disk 30 is designed such that the clutch disks 16, 20 are clamped to one another with a predefined clamping force. The tolerance compensation disk 30 can be formed by two or more partial disks of different or the same thickness. It can be seen in FIG. 1 that the screw 11 extends through the tolerance compensation disc 30, for which purpose the tolerance compensation disc 30 has a corresponding opening.It can furthermore be seen from FIG. 1 that the second clutch chamber inner wall 29 has a support collar 31 which projects axially into the clutch chamber 13 and is arranged radially centrally between the clutch disk carrier 14 and the hub connecting element 21. The overload protection clutch 22 is then axially supported on the support collar 31, wherein the clutch spring unit 27 bears radially centrally between the clutch disk carrier 14 and the hub connecting element 21 on the overload protection clutch 22. Accordingly, the support collar 31 and the clutch spring unit 27 bear against the overload protection clutch 22 at the height of half the effective diameter 32.According to the present example, the spur gear 1 also has a straight alignment pin 33, which is seated in a positive-locking manner in a first axial alignment pin receptacle 34 of the first ring gear body 7 on the one hand and in a second axial alignment pin receptacle 35 of the second ring gear body 8 on the other hand. By means of the alignment pin 33, the toothed rim bodies 7, 8 and consequently the helical toothed rims 9 a, 9 bare rotationally aligned with one another. As FIG. 1 shows, the alignment pin receptacles 34, 35 and the alignment pin 33 are arranged radially on the outside, here in the example between the helical gears 9 a, 9 band the clutch disk carrier 14, so that the rotational alignment of the ring gear bodies 7, 8 with respect to one another takes place close to the helical gears 9 a, 9 b. Optionally, it can be provided that the spur gear 1 has two or more such alignment pins 33 and consequently correspondingly many alignment pin receptacles 34, 35. The alignment pin is not involved in the axial clamping together of the toothed ring bodies 7, 8, but merely blocks a rotation of the toothed ring bodies 7, 8 relative to one another in relation to the spur wheel longitudinal central axis 6. It can be seen in FIG. 1 that the alignment pin 33 extends through the tolerance compensation disc 30, for which purpose the tolerance compensation disc 30 has a corresponding opening.The radial wall elements 7 a, 8 aof the respective sprocket body 7, 8 are each designed as a respective radial support element, by means of which the spur gear 1 is radially supported on the shaft main body 3 of the transmission shaft 2. One of the clutch chamber inner walls is formed by the respective radial wall element. Between the shaft main body 3 and the sprocket bodies 7, 8, a respective clearance fit 36 is formed. The toothed ring bodies 7, 8 or their radial wall elements 7 a, 8 aare designed with regard to their stability in such a way that they mainly transmit a radial force and are at most used for the transmission of the torque between the shaft main body 3 and the spur gear 1 or its double helical toothing 9.In order to keep a coefficient of friction prevailing between the clutch disks 16, 20 lying directly against one another constant during operation of the transmission shaft 2, it is furthermore provided according to the example that the transmission shaft 2 has shaft through-openings 37, which each open on the one hand into the hollow shaft interior 4 and on the other hand on or in the shaft connecting element 25, consequently into the clutch chamber. The respective shaft through-opening 37 functions as a lubricant feed channel for the overload protection clutch 22, During operation of the transmission shaft 2 or of the transmission having the transmission shaft 2, a lubricant, for example an oil, is introduced into the hollow shaft interior 4 of the transmission shaft 2, which lubricant flows through the shaft through-openings 37 and into the clutch chamber 13 as a result of centrifugal force. In addition, the present example provides that one or both of the toothed ring bodies 7, 8 has / have axial toothed ring body through openings 38 which each open on the one hand into the clutch chamber 13 and on the other hand on an outer wall of the corresponding toothed ring body 7, 8. The respective sprocket body through-opening 38 functions as a lubricant outlet channel for the overload protection clutch 22, lubricant which was introduced into the clutch chamber 13 during operation of the transmission shaft 2 can flow through the sprocket body through-openings 38 and out of the clutch chamber 13.Although the spur gear 1 is illustrated as an externally toothed spur gear up to now and in FIG. 1 only in its embodiment, it is to be understood that the spur gear 1 can also be an internally toothed spur gear, that is to say a ring gear. This means that the double bevel toothing 9 can be designed as an external toothing or as an internal toothing.The spur gear 1, the transmission shaft 2, the transmission and the motor vehicle each offer a possibility of how a particularly compact and powerful protection device for a motor vehicle transmission can be developed in order to avoid torque-induced damage. In this case, it is the basic principle of the concept of using an overload element-here the overload protection clutch 22. This allows a reduction of the required overload torque to components involved in torque transmission and thus a downsizing of these components, which in turn brings with it ecological (material saving) and economic advantages.List of reference characters1 Spur gear 2 Transmission shaft 3 Shaft main body 4 Hollow shaft interior 5 Transmission shaft longitudinal center axis 6 Spur gear longitudinal center axis 7 First ring gear body 7 aFirst radial wall element 8 Second ring gear body 8 aSecond radial wall element 9 Double helical gearing 9 aFirst helical gearing 9 bSecond helical gearing 10 Connecting device 11 Screw 12 Internal threaded hole 13 Clutch chamber 14 Clutch disk carrier 15 First clutch disk arrangement 16 First clutch disk 17 Carrier helical gearing 18 Clutch helical gearing 19 Second clutch disk arrangement 20 Second clutch disk 21 Hub connecting element 22 Overload protection clutch 23 Spur-gear-side hub helical gearing 24 Shaft main body-side hub helical gearing 25 Shaft connecting element 26 Outer circumferential surface 27 Clutch spring unit 27 a Cup spring 27 b Cup spring 28 First clutch chamber inner wall 29 Second clutch chamber inner wall 30 Tolerance compensation disk 31 Support collar 32 Effective diameter 33 Alignment pin 34 First alignment pin receptacle 35 Second alignment pin receptacle 36 Clearance fit 37 Shaft through hole 38 Sprocket body through holeReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 10,683,920 B2

[0003] DE 10 2020 101 349 A1

[0003]

Claims

Spur gear (1) for a transmission shaft (2), wherein the spur gear (1) has: - a first toothed ring body (7) with a first helical gear ring (9a) fixedly attached thereto, - a second toothed ring body (8) produced separately from the first toothed ring body (7) with a second helical gear ring (9b) fixedly attached thereto, wherein the helical gear rings (9a, 9b) have opposite skew angles, - a connecting device (10), by means of which the toothed ring bodies (7, 8) are fixed to one another in a rotationally fixed manner and are axially clamped to one another, wherein the toothed ring bodies (7, 8) delimit a clutch chamber (13) with one another, and wherein the helical gear rings (9a, 9b) together form a double helical gear (9) of the spur gear (1), - in the clutch chamber (13), one with one or both of the toothed ring bodies (7, 7, 8 Clutch disk carrier (14) which is connected in a rotationally fixed manner and to which a first clutch disk arrangement (15) is fastened in a rotationally fixed manner, - a second clutch disk arrangement (19) which engages into the first clutch disk arrangement (15) and has a hub connecting element (21) which is designed to be connected in a rotationally fixed manner to a shaft main body (3) of the transmission shaft (2), so that the two clutch disk arrangements (15, 19) in the clutch chamber (13) form an overload protection clutch (22) which acts in a frictionally locking manner and by means of which the ring gear bodies (7, 8) and the hub connecting element (21) are coupled in a rotationally fixed manner to one another in order to transmit a torque up to a predefined torque limit value.Spur gear (1) according to Claim 1, characterized bya clutch spring unit (27) which is supported on a first clutch chamber inner wall (28), wherein the overload protection clutch (22) is clamped between the clutch spring unit (27) and a second clutch chamber inner wall (29) which is axially opposite the first clutch chamber inner wall (28), as a result of which clutch plates (16, 20) of the clutch plate arrangements (15, 19) are axially clamped to one another by means of the clutch spring unit (27).Spur gear (1) according to Claim 2, characterized bya tolerance compensation disc (30) which is arranged between the first toothed ring body (7) and the second toothed ring body (8), wherein an axial thickness of the tolerance compensation disc (30) is designed such that the clutch discs (16, 20) are clamped to one another with a predefined clamping force when the toothed ring bodies (7, 8) are axially clamped to one another by means of the connecting device (10).Spur gear (1) according to Claim 2 or 3, characterized in that the second clutch chamber inner wall (29) has a supporting collar (31) which projects axially into the clutch chamber (13) and is arranged radially centrally between the clutch disc carrier (14) and the hub connecting element (21), wherein the overload protection clutch (22) is supported axially on the supporting collar (31), and the clutch spring unit (27) bears radially centrally between the clutch disc carrier (14) and the hub connecting element (21) on the overload protection clutch (22).Spur gear (1) according to one of the preceding claims, characterized bya straight alignment pin (33) which is seated on the one hand positively in a first axial alignment pin receptacle (34) of the first toothed ring body (7) and on the other hand positively in a second axial alignment pin receptacle (35) of the second toothed ring body (8), with the result that the toothed ring bodies (7, 8) and consequently the helical toothed rings (9a, 9b) are rotationally aligned with one another.Spur gear (1) according to one of the preceding claims, characterized in that the hub connecting element (21) has a hub spline toothing (23) which is configured to be connected in a rotationally fixed manner to a corresponding hub spline toothing (24) of a shaft connecting element (25) of the transmission shaft (2).Spur gear (1) according to one of the preceding claims, characterized in that the clutch disc carrier (14) has a carrier spline toothing (17), and the first clutch disc arrangement (15) has a corresponding clutch spline toothing (18), wherein the clutch disc carrier (14) and the first clutch disc arrangement (15) are fixed to one another in a rotationally fixed manner by the carrier spline toothing (17) and the clutch spline toothing (18) engaging one another.Spur gear (1) according to one of the preceding claims, characterized in that a radial wall element (7a, 8a) of the respective ring gear body (7, 8) is designed as a radial support element, by means of which the spur gear (1) can be radially supported on the shaft main body (3) of the transmission shaft (2).Spur gear (1) according to one of the preceding claims, characterized in that the double helical toothing (9) is formed as an external toothing or as an internal toothing.Spur gear (1) according to one of the preceding claims, characterized in that one or both of the toothed ring bodies (7, 8) has / have an axial toothed ring body through-opening (38), which opens on the one hand into the clutch chamber (13) and on the other hand on an outer wall of the corresponding toothed ring body (7, 8).Transmission shaft (2) which has a spur gear (1) designed according to one of the preceding claims, wherein the hub connecting element (23) of the second clutch disc arrangement (19) and a shaft connecting element (25) arranged on an outer circumferential surface (26) of the transmission shaft (2) are connected to one another in a rotationally fixed manner.Transmission shaft (2) according to Claim 11, characterized in that its shaft main body (3) is designed as a hollow shaft.Transmission shaft (2) according to Claim 12, characterized bya shaft through-opening (37) which opens on the one hand into a hollow shaft interior (4) of the transmission shaft (2) and on the other hand on or in the shaft connecting element (25) of the transmission shaft (2) and consequently into the clutch chamber (13).Transmission having a transmission shaft (2) designed according to one of Claims 11 to 13.Motor vehicle having a transmission designed according to Claim 14.

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