Tandem axle for automobiles, especially for commercial vehicles, automobiles, and methods of driving such automobiles.

Abstract

The present invention relates to a tandem axle (10) for an automobile, the tandem axle (10) comprising a drivable first axle (12), the first axle (12) comprising a first differential gear (30), the first wheels (14, 16) of the first axle (10) being drivable via the first differential gear (30). The first axle (12) includes a first drive shaft (32), the first drive shaft (32) being drivable via the first differential gear (30), the first wheels (14, 16). A drivable second axle (20) is provided, the second axle (20) comprising a second differential gear (34), the second wheels (22, 24) of the second axle (20) being drivable via the second differential gear (34). The second axle (20) includes a drive gear (40) which drives a second differential gear (34), and via the second differential gear (34), drives the second wheels (22, 24). The second axle (20) also includes a second drive shaft (36), which drives the drive gear (40). A clutch (70) is also provided.

Description

Technical Field

[0001] The present invention relates to a tandem axle for motor vehicles, particularly for commercial vehicles, according to the first part of claim 1. The present invention further relates to a motor vehicle, particularly a commercial vehicle, equipped with such a tandem axle. The present invention also relates to a method of operating a motor vehicle equipped with such a tandem axle according to the first part of claim 10.

Background Art

[0002] From Patent Document 1 and Patent Document 2, a tandem axle having two drivable axles is known. Each axle includes a differential gear, and the differential gear includes a drive gear drivable via a shaft as an input to the differential gear. Further, the axle includes two drive half-shafts for driving the wheels of this axle via the wheels of the axle shaft. Further, Patent Document 3 discloses a control method for a drive axle system.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of the present invention is to provide a tandem axle for automobiles, particularly for commercial vehicles, an automobile equipped with such a tandem axle, and a method of driving an automobile equipped with such a tandem axle, enabling particularly advantageous driving. This object is solved by a tandem axle having the features of claim 1, an automobile having the features of claim 9, and a method having the features of claim 10. Advantageous embodiments with further developments suitable for the object of the present invention are shown in the remaining claims. [Means for solving the problem]

[0005] A first aspect of the present invention relates to a tandem axle for an automobile (also simply called a vehicle). This means that an automobile, preferably designed as a commercial vehicle, particularly a truck, is equipped with a tandem axle in its completed state. The tandem axle comprises a drivable first axle (also called a first vehicle axle). The first axle comprises a first differential gear (also called a first differential, first balance gear, or first axle gear). The first wheels of the first axle are drivable via the first differential gear. These first wheels are also called first wheels. Furthermore, the first axle comprises a first drive shaft, by which the first drive shaft is drivable a first differential gear, and by which the first wheels are drivable via the first differential gear, thereby enabling the entire automobile to be driven, for example. The feature that the first axle is a drivable first axle means that the first wheels are drivable by the first drive shaft via the first differential gear.

[0006] A tandem axle further comprises a drivable second axle (also called a second vehicle axle) in addition to the first axle. In particular, these axles are arranged consecutively, i.e., towards the rear, in the longitudinal direction of the vehicle, with the second axle being particularly behind the first axle in the longitudinal direction of the vehicle. In particular, it is conceivable that the vehicle, in its completed state, comprises at least or exactly three axles (also called vehicle axles), namely a first axle, a second axle, and a third axle (also called a third vehicle axle). In particular, it is conceivable that the third axle is positioned in front of the first axle and in front of the second axle in the longitudinal direction of the vehicle, for example, the third axle being the front axle. For example, if the first axle is positioned between the third axle and the second axle in the longitudinal direction of the vehicle, then the first axle is, for example, the first rear axle, and therein, for example, if the second axle is positioned behind the first and third axles in the longitudinal direction of the vehicle, then the second axle is the second rear axle. In particular, in this way the first axle is, for example, the front rear axle, and the second axle is, for example, the rear rear axle.

[0007] The second axle is equipped with a second differential gear (also called the second differential gear, second balance gear, or second axle gear) in addition to the first differential gear. The second wheel of the second axle is drivable via the second differential gear, and the second wheel is also called the second wheel or second wheel. Hereafter, when "wheel" is used, it means the first wheel and the second wheel unless otherwise specified. Hereafter, when "axle" or "vehicle axle" is used, it means the first axle and the second axle unless otherwise specified. The wheels of the axle are ground contact elements that can or do support the vehicle downward relative to the ground in the direction of the vehicle's height. When the vehicle is running along the ground while being supported downward relative to the ground in the direction of the vehicle's height via the wheels, the wheels roll along the ground, especially straight. The characteristic that the second axle is a drivable second axle means that the second wheel of the second axle is drivable, and thereby, for example, the entire vehicle can be driven.

[0008] There, the second axle is equipped with a drive gear, which is also called, for example, a pinion or drive pinion. The drive gear is, for example, a bevel gear, also called a bevel gear. The drive gear drives the second differential gear, and through this second differential gear, the second wheel is driven, thereby driving, for example, the entire automobile. This means that the second differential gear is driven by the drive gear, or the second wheel is driven through the second differential gear. Furthermore, the second axle is equipped with a second drive shaft, which is provided in addition to the first drive shaft, and by this second drive shaft, the drive gear is driven, and through this drive gear, the second differential gear is driven. In this way, for example, the second differential gear can be driven by driving the drive gear, and the second wheel can be driven by driving the second differential gear. There, the drive gear can be driven by the second drive shaft, in particular by driving the second drive shaft. In this way, the second drive shaft can drive the drive gear, and the second differential gear can be driven via the drive gear. In particular, the second drive shaft is connected to the drive gear, especially permanently, to transmit torque, and especially so that they do not rotate relative to each other.

[0009] Within the framework of this disclosure, the feature that two components, such as a second drive shaft or a drive gear, are connected so as not to rotate relative to each other means that the components, connected so as not to rotate relative to each other, are coaxially arranged with respect to each other and, in particular when the components are driven, rotate together or simultaneously at the same angular velocity about a common component rotation axis with respect to the housing of a tandem axle.

[0010] The characteristic that two components, such as a second drive shaft or drive gear, are connected or coupled to each other to transmit torque means that the components are connected or coupled to each other to transmit torque, and are connected or coupled to each other so as not to rotate relative to each other, and further connected or coupled to each other to transmit torque.

[0011] The feature that two components, such as a second drive shaft or drive gear, are permanently connected or coupled to each other to transmit torque means that there is no switch element that allows switching between a coupled state in which the components are connected or coupled to each other to transmit torque and a separated state in which torque cannot be transmitted between the components via a switch element; rather, the components are always, and therefore permanently, connected or coupled to each other to transmit torque, that is, to transmit torque between the components. In this way, for example, one component can be driven by the other component or vice versa.

[0012] In particular, the feature that two components, such as a second drive shaft and a drive gear, are permanently connected or coupled to each other so as not to rotate relative to each other means that there is no switch element that can switch between a coupled state in which the components are connected or coupled to each other so as not to rotate relative to each other and a separated state in which the components are separated and cannot rotate relative to each other and torque cannot be transmitted between the components, and instead the components are always, and therefore permanently, connected or coupled to each other so as not to rotate relative to each other.

[0013] The tandem axle is further equipped with a clutch, which is designed, for example, as a multi-disc clutch. The clutch is switchable between a clutch-engaged and a clutch-disengaged state, in particular by controlling the clutch. For example, the clutch is electrically or electronically controlled by a computer or the like, thereby allowing the clutch to be switched, for example, intentionally and therefore actively, between a clutch-engaged and a clutch-disengaged state. In the engaged state, the second drive shaft is coupled to the drive shaft by the clutch, i.e., through the clutch, to transmit torque, thereby allowing the second drive shaft to be driven by the first drive shaft via the clutch. In this way, in the engaged state, the second wheel can be driven by the first drive gear via the second differential gear and the second drive shaft, and in particular, at the same time, the first wheel can be driven by the first drive shaft via the first differential gear, for example, allowing both the first and second wheels to be driven simultaneously.

[0014] In the separated state, the second drive shaft is separated from the first drive shaft, and the first drive shaft cannot drive the second drive shaft via the clutch; therefore, the driving of the second drive shaft by the first drive shaft via the clutch is stopped or prevented.

[0015] For example, an automobile, in its completed state, is equipped with at least one or just one drive motor, which can be designed as, for example, an internal combustion engine or an electric motor. For example, a first drive shaft can be driven by a drive motor, thereby driving a first wheel, and in particular a second wheel in a coupled state, by the drive motor.

[0016] For example, in the completed state of a vehicle equipped with a tandem axle, the first wheels are positioned on opposite sides of the vehicle in the lateral direction. Furthermore, it is preferable that the second wheels are also positioned on opposite sides of the vehicle in the lateral direction.

[0017] To achieve particularly advantageous driving of the automobile, according to the present invention, the second axle comprises an axle housing, within which a drive gear rotatable relative to the axle housing is housed at least partially, particularly at least largely, therefore at least half or completely. Since the drive gear is rotatable relative to the axle housing and housed, i.e., positioned within the axle housing, the drive gear is housed, i.e., positioned within the axle housing in such a rotatable manner. In particular, the housing space of the axle housing is particularly directly defined by the axle housing, particularly by the inner circumferential surface of the axle housing, and the drive gear is housed at least partially, particularly at least largely, therefore at least half or completely within the housing space in such a rotatable manner. In this way, the second drive shaft is also rotatable relative to the axle housing. The axle housing is also called a carrier or axle carrier. Furthermore, for example, the second wheel can rotate relative to the axle housing, particularly around its respective wheel axis of rotation.

[0018] According to the present invention, the tandem axle further comprises a rotational speed sensor capable of detecting, i.e., measuring, the rotational speed of the drive gear. The rotational speed sensor comprises a detection element mounted on the axle housing, which is mounted on the axle housing in particular to stop, and thus prevent, relative motion between the detection element and the axle housing. Furthermore, the rotational speed sensor comprises a sensor element that is permanently coupled to the drive gear so as not to rotate relative to each other, the rotational speed of this sensor element being detectable by a receiving element, and thereby the rotational speed of the drive gear being detectable by the rotational speed sensor. The sensor element can be coupled directly or indirectly to the drive gear such that the sensor element is permanently coupled to the drive gear so as not to rotate relative to each other. In this way, the sensor element can rotate with the drive gear relative to the axle housing and relative to the detection element. Since the sensor element is permanently coupled to the drive gear so as not to rotate relative to each other, the rotational speed of the sensor element matches the rotational speed of the drive gear, and vice versa, and the rotational speed of the drive gear can be detected or determined by detecting the rotational speed of the sensor element. In this way, the receiving element can detect or obtain the rotational speed of the sensor element, and thereby the rotational speed of the drive gear can be detected or obtained. In the present invention, the rotational speed of the drive gear can be detected particularly advantageously and particularly robustly, which, for example, enables particularly advantageous driving of the automobile according to the detected rotational speed of the drive gear. In the present invention, it has been confirmed that the detection of the rotational speed of the drive gear is not excessively affected, and moreover, in the present invention, the detection of the rotational speed of the drive gear is not excessively affected by liquids such as working fluid. Therein, the present invention is based particularly on the following findings and considerations: It is desirable that the measured quantity can be detected, that is, measured, and that, based on the measured quantity, it is possible to determine whether the clutch is currently engaged or disengaged. When the clutch is engaged, the clutch is closed. When the clutch is disengaged, the clutch is open.In principle, one could consider integrating a sensor into the clutch, for example, by placing it in a component such as the clutch assembly, so that the aforementioned measurement quantity can be detected by the sensor, and based on that, it could be determined whether the clutch is currently closed or open. However, especially during the operation of a tandem axle, a liquid is supplied to the clutch, specifically formed as a fluid, which is, for example, the aforementioned working fluid, and this liquid is, for example, oil. The clutch is actuated, and / or lubricated, and / or cooled, for example, by oil. By supplying oil to the clutch, the aforementioned sensor, such as a switch, may be exposed to an excessive amount of oil, thereby potentially reducing the sensor's ability or possibility to detect the measurement value to an undesirable degree. Alternatively or in addition, for example, exposure of the sensor to oil may also potentially reduce the sensor's ability or possibility to provide, for example, an electrical transmission signal that characterizes the measurement value. The aforementioned computer, sometimes called a control unit or designed as such, is fundamentally designed to receive sensor signals provided by a sensor, thereby enabling the computer to determine, based on the sensor signals characterizing the received measurements, whether the clutch is currently closed or open. For example, the aforementioned sensor could be designed as a position sensor to detect the position of the aforementioned clutch components, such that its position corresponds to the aforementioned measurement. In particular, integrating a sensor into the clutch in this way could lead to leakage, for example, allowing fluid to enter the sensor housing, especially the switch housing, potentially causing sensor failure.

[0019] The present invention can avoid the aforementioned problems and drawbacks. According to the present invention, the rotational speed of the drive gear can be used as the aforementioned measurement, and based on this measurement, it can be determined whether the clutch is currently closed or open. By mounting the detection element to the axle housing and connecting the sensor element to the drive gear so that it does not rotate relative to each other, undesirable excessive influence on the detection of the rotational speed of the drive gear can be avoided. For example, if the rotational speed sensor detects that the rotational speed of the drive gear is not zero, in particular greater than zero, and the drive gear is rotating relative to the axle housing, it can be determined that the clutch is closed. This is because, in that case, the drive gear is driven by the second drive shaft, and the second drive shaft is driven by the first drive shaft via the clutch, which is only possible in the coupled state, in terms of coupled and uncoupled states. However, if, for example, the rotational speed sensor detects that the rotational speed of the drive gear is zero, in particular the current rotation, and therefore the drive gear is not rotating, it can be estimated or determined that the clutch is currently open, in particular while the first drive shaft is rotating, in particular while the first drive shaft is driven and rotating by the drive motor. This is because, in that case, the drive gear is not driven by the second drive shaft, and the second drive shaft is not driven by the first drive shaft via the clutch, which is only possible, or rather, plausible, in the disengaged state, in terms of the coupled and disengaged states.

[0020] Preferably, the rotational speed sensor is designed to provide a particularly electrical signal that characterizes the rotational speed of the drive gear detected by the sensor. The aforementioned computer receives this signal and can then determine, based on the detected rotational speed of the drive gear characterized by this signal, whether the clutch is currently closed or open. Subsequently, for example, the computer can operate the vehicle, particularly the clutch, in response to the signal, i.e., in response to the detected rotational speed of the drive gear. In particular, a control strategy can be implemented for operating the vehicle, particularly for operating the tandem axle, and particularly for operating the clutch, in response to the detected rotational speed of the drive gear. In particular, for example, to operate the clutch in response to the detected rotational speed of the drive gear, it is conceivable to switch the clutch between a engaged and disengaged state in response to the detected rotational speed of the drive gear.

[0021] In order to particularly advantageously detect the rotational speed of the drive gear and thereby realize particularly advantageous driving of the vehicle in accordance with the particularly detected rotational speed of the drive gear, in one embodiment of the present invention, a sensor element is designed separately from the drive gear and is permanently coupled to the drive gear so as not to rotate relative to each other.

[0022] A further embodiment is characterized in that the drive gear comprises a tooth portion (also referred to as the first tooth portion) and a shaft stub formed integrally with the tooth portion, and a sensor element is provided on the shaft stub, particularly formed or arranged. When the "tooth portion" is mentioned above or below, unless otherwise specified, it means the first tooth portion of the drive gear. The feature that the tooth portion and the shaft stub are integrally formed with each other means that the tooth portion and the shaft stub are made from a single part. In other words, the tooth portion and the shaft stub are preferably of an integral type, that is, integrally formed, and thus made from a single part, and this body is integrally formed, and thus made from a single part, and thus is a monoblock integrally manufactured. This means that preferably, the tooth portion and the shaft stub are not formed as parts separately formed and joined to each other, but preferably, the tooth portion and the shaft stub are made from a single part, that is, integrally formed with each other, and thus made as a monoblock or by a monoblock. For example, the tooth portion meshes with the second tooth portion of the second gear of the differential gear, and the second gear and thus the second differential gear can be driven by the drive gear. For example, the second gear is a ring gear. For example, the second gear is connected to the differential housing of the second differential gear, which is designed as a differential carrier or also called a differential carrier, in particular permanently, so as not to rotate relative to each other.

[0023] Preferably, the sensor element is provided on the shaft stub, the tooth portion is integrally formed with the shaft stub, and the tooth portion and the shaft stub rotate or can rotate at the same rotational speed as the drive gear with respect to the axle housing, so that the rotational speed of the drive gear can be detected particularly advantageously and robustly by the receiving element and the sensor element, and in particular, based on the detected rotational speed of the drive gear, the advantageous operation of the automobile can be guaranteed.

[0024] More preferably, the sensor element is formed separately from the shaft stub and thus separately from the toothing, and in particular is permanently connected to the shaft stub so as not to rotate relative to each other. Thereby, the rotational speed of the drive gear can be detected particularly robustly. This means that excessive influences that the detection of the rotational speed of the drive gear might have can be avoided, or that the rotational speed of the drive gear can be advantageously detected even if such influences exist.

[0025] A further embodiment is characterized in that the tandem axle has a spacer element formed separately from the drive gear, and this spacer element is connected to the drive gear, in particular permanently, so as not to rotate relative to each other. For example, the spacer element is a ring, i.e., annular, and for example, the spacer element runs completely around, i.e., completely closes, the circumferential direction of the drive gear (the axial direction of which is perpendicular to the radial direction of the drive gear). There, the circumferential direction of the drive gear runs around the axial direction of the drive gear. In particular, the drive gear can rotate around the gear rotation axis relative to the axle housing, and the axial direction of the drive gear coincides with the gear rotation axis. By means of the spacer element, two bearings for rotatably mounting the drive gear in the axle housing are held spaced apart from each other in the axial direction of the drive gear. For example, these bearings are formed as rolling bearings, in particular ball bearings, in order to achieve a low-friction mounting of the drive gear.

[0026] Furthermore, there, a sensor element formed separately from the drive gear and separately from the spacer element is connected to the spacer element, in particular permanently, so as not to rotate relative to each other, and in particular exclusively via the spacer element, to the drive gear, in particular permanently, so as not to rotate relative to each other. In that way, the spacer element, the sensor element and the drive gear rotate relative to the axle housing, in particular around the gear rotation axis, at an equal or the same rotational speed, so that the rotational speed of the drive gear can be detected particularly robustly and thus reliably and accurately.

[0027] It has been shown that it is particularly advantageous if the sensor element surrounds the spacer element at least partially, especially at least most, and therefore at least half or completely, in the circumferential direction of the drive gear as it runs around the drive gear in the axial direction. This allows for robust and accurate detection, i.e., measurement, of the rotational speed of the drive gear.

[0028] In a further particularly advantageous embodiment of the present invention, a spacer element formed separately from the drive gear, and thereby separately from the shaft stub, and thereby separately from the teeth, is coupled to the shaft stub, particularly permanently, so as not to rotate relative to each other, and completely surrounds the shaft stub, that is, completely encircles the shaft stub, in the axial direction of the drive gear, and therefore in the circumferential direction of the drive gear. In particular, the teeth of the drive gear are connected to the shaft stub in the axial direction of the drive gear, and for example, the teeth of the drive gear have a larger diameter than the shaft stub, and in particular, the maximum diameter of the teeth, particularly the outer diameter, is greater than the maximum diameter of the shaft stub, particularly the outer diameter. In this way, the sensor element is provided on the shaft stub so as to be coupled to the shaft stub, particularly permanently, so as not to rotate relative to each other, by a spacer element formed separately from the drive gear, and thereby separately from the shaft stub, and the sensor element is coupled to the spacer element and, through it, to the shaft stub, particularly permanently, so as not to rotate relative to each other. This allows for robust and accurate measurement of the drive gear's rotational speed, thereby enabling the vehicle to be driven with particular advantage based on the measured, i.e., detected, drive gear's rotational speed.

[0029] Finally, it has been shown to be particularly advantageous if the rotational speed sensor is equipped with a connection device that can or connect the rotational speed sensor to at least one wiring, particularly separately formed from the rotational speed sensor. There, the connection device is located outside the axle housing, particularly outside the housing space, and the connection device is located, for example, around the axle housing. In particular, the rotational speed sensor can provide the aforementioned preferred electrical signal via the connection device, and the rotational speed sensor can transmit its signal to the wiring via the connection device. In this way, the wiring receives the signal via the connection device and sends the signal particularly to a computer, and in this way the computer can receive the signal sent and provided or that may be provided by the wiring. By locating the connection device of the rotational speed sensor outside the axle housing, the connection device is prevented from being excessively exposed to the aforementioned working fluid, such as oil, and the signal can be transmitted reliably and robustly. As a result, the vehicle can be shown to be driven based on the signal characterizing the detected rotational speed of the drive gear. Since the connecting device (also called the coupling element, coupling device, or rotational speed sensor coupling element) is located outside the axle housing (also called the carrier), it is possible to prevent the connecting device from being exposed to excessive oil leakage. This also prevents failure due to lateral load vibration and allows for robust and accurate detection of the rotational speed of the drive gear.

[0030] A second aspect of the present invention relates to an automobile (also simply called a vehicle) equipped with a tandem axle according to a first aspect of the present invention. Advantages and favorable embodiments of the first aspect of the present invention are deemed to be advantages and favorable embodiments of the second aspect of the present invention, and vice versa.

[0031] A third aspect of the present invention relates in particular to a method for driving an automobile (also simply called a vehicle) equipped with a tandem axle according to the first aspect of the present invention. In this method, the tandem axle comprises a drivable first axle, the first axle comprising a first differential gear, the first wheel of the first axle being drivable via the first differential gear. In this method, the first axle comprises a first drive shaft, the first drive shaft being drivable to a first differential gear, the first wheel being drivable via the first differential gear. In this method, the tandem axle comprises a drivable second axle, the second axle comprising a second differential gear, the second wheel of the second axle being drivable via the second differential gear. The second axle comprises a drive gear, the drive gear being drivable to a second differential gear, the first wheel being drivable via the second differential gear. The second axle further comprises a second drive shaft, the drive shaft being drivable to a drive gear. In this method, the tandem axle is equipped with a particularly switchable clutch that can be switched between a coupled state and a disengaged state. In the coupled state, the second drive shaft is coupled to the first drive shaft by the clutch, i.e., via the clutch, to transmit torque, thereby the second drive shaft is driveable, and specifically driven, by the first drive shaft via the clutch. In the disengaged state, the second drive shaft is disengaged from the first drive shaft.

[0032] In order to enable the automobile to be driven particularly advantageously, in a third aspect of the present invention, the second axle has an axle housing, and a drive gear rotatable relative to the axle housing is housed, i.e., positioned within the axle housing. A rotational speed sensor is also provided to detect the rotational speed of the drive gear. For this purpose, the rotational speed sensor comprises a detection element mounted on the axle housing and a sensor element that is particularly permanently coupled to the drive gear so as not to rotate relative to each other, the sensor element being directly or indirectly coupled to the drive gear and coupled so as not to rotate relative to each other. The rotational speed of the sensor element is detected by the receiving element, and thereby the rotational speed sensor detects the rotational speed of the drive gear, in particular because the rotational speed of the sensor element includes the rotational speed of the drive gear. This is particularly because the sensor element is particularly permanently coupled to the drive gear so as not to rotate relative to each other. Furthermore, in a method according to the third aspect of the present invention, the automobile is driven according to the rotational speed of the drive gear detected, i.e., measured by the rotational speed sensor. There, for example, the clutch is switched between a engaged state and a disengaged state according to the rotational speed of the drive gear detected by a rotational speed sensor. The advantages and advantageous embodiments of the first and second embodiments of the present invention can be seen from the advantages and advantageous embodiments of the third embodiment of the present invention, and vice versa.

[0033] In particular, it is conceivable to operate the tandem axle in accordance with the detected rotational speed of the drive gear. Preferably, the clutch is designed as a multi-plate clutch, which preferably comprises a plurality of multi-plate discs that are continuous in the axial direction of the clutch, particularly as the aforementioned plates.

[0034] In particular, in the control strategy, it is conceivable that the clutch may be switched between a engaged and disengaged state, especially depending on the current speed of the vehicle (also called the driving speed). Alternatively, or in addition to that, in particular, in the control strategy, the clutch may be switched between a engaged and disengaged state, for example, depending on the slip of at least one wheel. In particular, in the control strategy, it is conceivable that the second axle may be selectively coupled to or disengaged from the first axle, especially depending on the current driving conditions. To couple the second axle to the first axle, that is, to couple the second axle to the first axle, the clutch is closed, that is, the clutch is put into the engaged state. To disengage the second axle from the first axle, the clutch is opened, that is, put into the disengaged state. In this way, in particular, in the aforementioned control strategy, it is conceivable that the clutch may be switched between a engaged and disengaged state, especially depending on the current driving conditions of the vehicle.

[0035] For example, the sensor element is designed as an annular, and therefore measuring ring, which is particularly closed, and therefore completely encircles, the drive gear, for example, in the circumferential direction, around the drive gear, which runs axially. For example, the sensor element is connected to the drive gear by press-fit so as not to rotate relative to each other. There, it is particularly conceivable that the sensor element is pressed against the drive gear, especially the shaft stub. The sensor element is connected to a spacer element by press-fit so as not to rotate relative to each other, for example, it is particularly conceivable that the sensor element is pressed against the spacer element. The spacer element is connected to the drive gear, especially the shaft stub, by press-fit so as not to rotate relative to each other. There, for example, the spacer element is pressed against the drive gear, especially the shaft stub. The sensor element provides information to a receiving element, which can detect the rotational speed of the sensor element, and thus the rotational speed of the drive gear, based on that information. For this purpose, the sensor element has, for example, a recess, which can be formed, for example, as a blind hole or a through hole. Furthermore, the sensor element has, for example, a sub-region in addition to the recess, which is formed, for example, as a projection (also called a convex portion). These aforementioned sub-regions of the sensor element are raised outward relative to the recess, particularly in the radial direction of the drive gear and therefore in the radial direction of the sensor element, while the recess is recessed inward relative to these sub-regions, for example, in the radial direction of the drive gear. In particular, the recess and sub-region of the sensor element are arranged alternately and continuously in the circumferential direction of the drive gear and therefore in the circumferential direction of the sensor element as it moves around the axial direction of the drive gear. The receiving element is formed to detect the rotational speed of the sensor element, and therefore the rotational speed of the drive gear, based on the recess and sub-region of the sensor element, particularly when the drive gear and therefore the sensor element are rotating. In this way, the recess and sub-region form a kind of sawtooth, which allows the receiving element to detect the rotational speed of the sensor element and therefore the rotational speed of the drive gear. This ensures robust and accurate detection, i.e., measurement, of the rotational speed of the drive gear.

[0036] For example, an axle housing is designed as a cast part and manufactured by casting. However, the axle housing also includes mounting elements for attaching, for example, a receiving element to the axle housing. In particular, the mounting elements may be manufactured by the same casting method as the axle housing. For example, the sensor element is made from sheet metal.

[0037] The present invention makes it possible to robustly and accurately detect the current state of the clutch. This means that the present invention makes it possible to robustly and accurately determine whether the clutch is currently engaged or disengaged. In particular, the present invention makes it possible to identify the following errors or their causes.

[0038] - Specifying a clutch that is inappropriate for the intended use - The algorithm causes the clutch to go through more cycles than expected. - Errors during laser welding - Failure of the air valve in the car - Too high starting torque

[0039] Further advantages, features, and details of the present invention will become apparent from the following description of preferred embodiments and the drawings. The features and combinations of features described herein, as well as the features and combinations of features described in the following description of the drawings and / or shown only in the drawings, can be used not only in the combinations described herein, but also in other combinations or individually, without departing from the scope of the present invention. [Brief explanation of the drawing]

[0040] [Figure 1] A schematic diagram of a tandem axle for automobiles. [Figure 2] A schematic perspective view of the axle housing of a tandem axle. [Figure 3] Another schematic perspective view of the axle housing. [Figure 4] A schematic perspective view of another part of the axle housing. [Figure 5] A schematic perspective view of another part of the axle housing. [Figure 6] A schematic perspective view of the receiving element of the tandem axle. [Figure 7] A schematic perspective cross-sectional view of the axle housing and drive gear of a tandem axle. [Figure 8] A schematic perspective view of a sensor element designed as a measuring ring for a tandem axle. [Figure 9] A schematic perspective view of the tandem axle structural unit including the sensor element. [Figure 10] A block diagram illustrating how to drive a car. [Modes for carrying out the invention]

[0041] In the diagram, identical or functionally equivalent elements are given the same reference number.

[0042] Figure 1 schematically shows a tandem axle 10 for an automobile (also simply called a vehicle, preferably designed as a commercial vehicle, particularly a truck). The tandem axle 10 comprises a drivable first axle 12, the first axle 12 comprising first wheels 14 and 16. The wheels 14 and 16 are positioned on opposite sides of the automobile in the lateral direction, which is indicated by a double arrow 18. The tandem axle 10 further comprises a second axle 20, the second axle 20 comprising second wheels 22 and 24. The wheels 22 and 24 are positioned on opposite sides of the automobile in the lateral direction; for example, wheels 14 and 22 are positioned on the first side of the automobile, and wheels 16 and 24 are positioned on the second side of the automobile, with the first and second sides being opposite each other in the lateral direction of the automobile. It can be seen that the wheels 14, 16, 22 and 24 are twin wheels and therefore each has twin tires. Wheels 14, 16, 22, and 24 are ground contact elements through which the vehicle can or does support the vehicle downward relative to the ground in the vehicle's height direction. The vehicle's height direction is perpendicular to the image plane of Figure 1 and therefore also perpendicular to the vehicle's lateral direction, indicated by double arrow 26. Axles 12 and 20 are positioned longitudinally in the vehicle's longitudinal direction, with axle 20 following axle 12 behind in the vehicle's longitudinal direction. The vehicle's longitudinal direction is perpendicular to the vehicle's lateral direction and perpendicular to the vehicle's height direction, indicated by double arrow 28. Each axle 12, 20 is also referred to as the respective vehicle axle.

[0043] The characteristic that axle 12 is a drivable axle means that not only the entire vehicle but also the wheels 14 and 16 are drivable. For this purpose, the first axle 12 is equipped with a first differential gear 30, and the wheels 14 and 16 of the axle 12 are drivable via the first differential gear 30. Furthermore, the first axle 12 is equipped with a drive shaft 32, which is drivable by, for example, the vehicle's drive motor (not shown). By driving the first drive shaft 32, the differential gear 30 is drivable by the first drive shaft 32, and by driving the first differential gear 30, the wheels 14 and 16 are drivable. In this way, the first differential gear 30 is drivable by the first drive shaft 32, and the wheels 14 and 16 are drivable via the first differential gear 30.

[0044] The feature that the second axle 20 is drivable, and therefore a drivable axle, means that the wheels 22 and 24 of the axle 20, and thus the entire vehicle, are drivable. For this purpose, the second axle 20 is provided with a second differential gear 34, in particular in addition to the first differential gear 30. Furthermore, the second axle 20 is provided with a second drive shaft 36, and by driving the second drive shaft 36, the second differential gear 34 is drivable by the second drive shaft 36. By driving the differential gear 34, the wheels 22 and 24 are drivable. In this way, the second differential gear 34 is drivable by the second drive shaft 36, and the wheels 22 and 24 are drivable via the second differential gear 34.

[0045] The first axle 12 includes a first drive gear 38, which is formed, for example, as a first bevel gear. The first drive gear 38 is drivable by a first drive shaft 32, for example, by the drive gear 38 being coupled to the drive shaft 32 in particular so as not to rotate permanently relative to each other. The second axle 20 includes a second drive gear 40 provided in addition to the drive gear 38. The drive gear 38 is drivable by a first differential gear 30, which drives the first wheels 14 and 16; the drive shaft 32 is drivable by a drive gear 38, which drives the differential gear 30, which drives the wheels 14 and 16; the second drive gear 40 is drivable by a second differential gear 34, which drives the second wheels 22 and 24. In this way, by driving the drive shaft 36, the drive gear 40 becomes drivable, by driving the drive gear 40, the differential gear 34 becomes drivable, and by driving the differential gear 34, the wheels 22 and 24 become drivable. In this way, the wheels 22 and 24 are drivable by the drive gear 40 via the differential gear 34, and the wheels 14 and 16 are drivable by the first drive gear 38 via the differential gear 30. For example, the first drive gear 38 is formed as a bevel gear. For example, the second drive gear 40 is formed as a bevel gear.

[0046] Figure 1 shows that each differential gear 30 and 34 is equipped with its respective input gears 42 and 44. Each input gear 42 and 44 is a gear. For example, each input gear 42 and 44 is a ring gear. There, the drive gear 38 meshes with the input gear 42, and the drive gear 40 meshes with the input gear 44. For this purpose, for example, the drive gear 38 is equipped with a first tooth section, and the input gear 42 is equipped with a second tooth section, and the first tooth section meshes with the second tooth section, thereby allowing the drive gear 38 to mesh with the input gear 42. The drive gear 40 is equipped with, for example, a third tooth section, and the input gear 44 is equipped with, for example, a fourth tooth section, and the third tooth section meshes with the fourth tooth section, thereby allowing the drive gear 40 to mesh with the input gear 44. For example, each differential gear 30 and 34 is equipped with its respective differential housing 46 and 48, and each differential housing 46 and 48 is formed, for example, as its respective differential carrier. Furthermore, each differential gear 30, 34 is equipped with balance gears 50, 52, and each differential gear 30, 34 is equipped with output gears 54, 56. Balance gear 50 and output gear 54 are gears, and balance gear 50 meshes with output gear 54. Balance gears 52, 56 are gears, and balance gear 52 meshes with output gear 56. Each balance gear 50, 52 is mounted at least indirectly to each differential housing 46, 48 so as to be able to rotate around a first axis of rotation relative to each differential housing 46, 48. Each output gear 54, 56 can rotate around a second axis of rotation relative to each differential housing 46, 48, and each second axis of rotation is perpendicular to each first axis of rotation. By driving each differential housing 46, 48, which is drivable by driving each differential gear 30, 34, the balance gears 50, 52 are drivable, and by driving the balance gears 50, 52, the output gears 54, 56 are drivable. By driving the output gear 54, wheels 14 and 16 can be driven, and by driving the output gear 56, wheels 22 and 24 can be driven. In the embodiment shown in Figure 1, the differential gears 30 and 34 are designed as bevel differential gears.

[0047] The first axle 12 includes first side shafts 58 and 60, where side shaft 58 is drivable by a first output gear 54 and side shaft 60 is drivable by a second output gear 54. For example, side shaft 58 is permanently coupled to the first output gear 54 to transmit torque, and side shaft 60 is permanently coupled to the second output gear 54 to transmit torque. By driving side shaft 58, the side shaft 58 can drive the wheel 14, and by driving side shaft 60, the side shaft 60 can drive the wheel 16. Thereafter, by driving the first output gear 54, the first output gear 54 can drive side shaft 58, and the second output gear 54 can drive side shaft 60.

[0048] The second axle 20 includes a third side shaft 62 assigned to a wheel 22, which is assigned to a first output gear 56. The second axle 20 further includes a fourth side shaft 64 assigned to a wheel 24, which is assigned to a second output gear 56. By driving the side shaft 62, the wheel 22 can be driven by the side shaft 62, and by driving the side shaft 64, the wheel 24 can be driven by the side shaft 64. By driving the first output gear 56, the side shaft 62 can be driven by the first output gear 56, and the wheel 22 can be driven by the drive gear 56 via the side shaft 62. By driving the second output gear 56, the side shaft 64 can be driven by the second output gear 56, and the wheel 24 can be driven by the second output gear 56 via the side shaft 64. There, the axle 20 includes a first clutch device 66 assigned to a first output gear 56 and a side shaft 62, and a second clutch device 68 assigned to a second output gear 56 and a side shaft 64. Each clutch device 66, 68 can be switched between its respective engaged state and its respective disengaged state, in particular by electrical or electronic control of each clutch device 66, 68. In the respective engaged state of each clutch device 66, 68, the respective side shafts 62, 64 assigned to each clutch device 66, 68 are coupled to the assigned, and therefore associated, respective output gear 56 via the respective clutch devices 66, 68 to transmit torque, and in the engaged state of the clutch devices 66, 68, the output gear 56 can drive the side shafts 62 and 64, and therefore the wheels 22 and 24, via the clutch devices 66 and 68. In contrast, in the disengaged state of each clutch device 66, 68, the assigned and therefore associated side shafts 62, 64 are separated from the assigned and therefore associated output gear 56, and in the disengaged state of the clutch devices 66, 68, the output gear 56 cannot drive the side shafts 62 and 64, and therefore the wheels 22 and 24.

[0049] The tandem axle 10 further includes a clutch 70 provided in addition to the clutch devices 66 and 68, the clutch 70 preferably being formed as a multi-plate clutch. More preferably, the clutch 70 is formed as a multi-plate clutch, the multi-plate clutch including a plurality of thin-layer discs arranged continuously in the axial direction of the clutch 70 as the aforementioned discs. The clutch 70 is switchable between a coupled state and a disengaged state. In the coupled state, the second drive shaft 36 is coupled to the first drive shaft 32 by the clutch 70 to transmit torque, thereby the second drive shaft 36 is driveable by the first drive shaft 32 via the clutch 70. In the disengaged state, the second drive shaft 36 is disengaged from the first drive shaft 32, thereby the drive shaft 36 is not driveable by the drive shaft 32 via the clutch 70.

[0050] In the embodiment shown in Figure 1, a third drive gear 72 is coupled to the drive shaft 32 so as not to rotate relative to each other, in particular permanently. A fourth drive gear 74 is coupled to the input element 76 of the clutch 70 so as not to rotate relative to each other, in particular permanently. For example, the drive gears 72 and 74 are designed as spur gears. The drive gears 72 and 74 mesh with each other. For example, the input element 76 is or includes a first thin-layer carrier. By thin-layer discs, the input element 76 can be coupled to the output element 78 of the clutch 70 so as not to rotate relative to each other, in order to transmit torque, for example, the output element 78 is or includes a second thin-layer carrier. The drive shaft 36 is drivable by the output element 78 of the clutch 70, in particular, the drive shaft 36 is drivable by being coupled to the output element 78 so as not to rotate relative to each other, in order to transmit torque, in particular permanently. In the clutch 70 engaged state, the output element 78 is thus driveable by the drive shaft 32 via the input element 76 and drive gears 72 and 74, thereby allowing the drive shaft 32 to drive the drive shaft 36 via the clutch 70. In the disengaged state, the output element 78 is separated from the input element 76, and the input element 76, and therefore the drive shaft 32, cannot drive the output element 78, and therefore the drive shaft 36.

[0051] For example, each clutch device 66, 68 is formed as its own meshing clutch, and each clutch device 66, 68 can reliably connect each side shaft 62, 64 to its respective associated output gear 56.

[0052] Looking at Figure 2 in particular, it can be seen that the second axle 20 is equipped with an axle housing 80 (also called a carrier or axle carrier), and that each wheel 22, 24 is rotatable relative to the axle housing 80, particularly around its respective wheel axis of rotation. The axle housing 80 is also clearly visible in Figures 3 and 4. The axle housing 80 is also clearly visible in Figures 5 and 7. Figure 7 in particular shows that the housing space 84 is defined particularly directly by the axle housing 80, especially by the inner circumferential surface 82 of the axle housing 80. There, the second drive gear 40 is housed in the housing space 84, and therefore within the axle housing 80. The drive gear 40 is rotatable relative to the axle housing 80, around the gear axis 86, which runs in the axial direction of the drive gear 40, and its radial direction is perpendicular to the axial direction of the drive gear 40. Here, the axial direction of the drive gear 40 coincides with the gear axis 86. Furthermore, Figures 7-9 clearly show that the tandem axle 10 is equipped with a rotational speed sensor 88, which allows for the detection of the rotational speed of the drive gear 40. When the drive gear 40 is driven by the drive shaft 36, the drive gear 40 rotates around the gear rotation axis 86 relative to the axle housing 80 (for example, the housing of the tandem axle 10 mentioned above) at the rotational speed of the drive gear 40. Figures 7 and 5 show a coupling element 90 formed separately from the drive gear 40 and permanently coupled to the drive gear 40 so as not to rotate relative to each other. This coupling ensures that, for example, the drive gear 40 is permanently coupled to the drive shaft 36 so as not to rotate relative to each other, in order to transmit torque.

[0053] The rotational speed sensor 88 is formed separately from the axle housing 80 and comprises a receiving element 92 attached to the axle housing 80 and a sensor element 94, which is particularly clear from Figure 8. In the embodiment shown in the figure, the sensor element is formed as an annular, and therefore as a ring. The ring is also called a measuring ring. The sensor element 94 is coupled to the drive gear 40 in a particularly permanent manner so as not to rotate relative to each other, and the rotational speed of the sensor element 94 can be detected by the receiving element 92. By detecting the rotational speed of the sensor element 94, the rotational speed of the drive gear 40 can be detected because the sensor element 94 is coupled to the drive gear 40 so as not to rotate relative to each other, and the rotational speed of the sensor element 94 matches the rotational speed of the drive gear 40. From Figure 8, it can be seen that the sensor element 94 has a recess 96, which in this example is formed as a through hole. More precisely, each further sub-region 98 of the sensor element 94 is positioned between each pair of recesses 96 that run axially around the drive gear 40, and are therefore directly continuous in the circumferential direction of the sensor element 94, and thus adjacent to each other, and the recesses 96 and sub-regions 98 are arranged alternately and continuously in the circumferential direction of the drive gear 40, and thus the sensor element 94. The circumferential direction of the drive gear 40, and thus the sensor element 94, is indicated by the double arrow 100 in Figure 7. When the drive gear 40, and thus the sensor element 94, rotates around the gear rotation axis 86 relative to the axle housing 80, for example, the alternately continuous recesses 96 and sub-regions 98 cause changes in the measurement signal provided by, for example, the rotational speed sensor 88, and in response to these changes, the respective rotational speeds, i.e., the rotational speed of the drive gear 40, can be detected.

[0054] The second tooth of the aforementioned drive gear 40 is partially visible in Figure 7 and labeled 102. The drive gear 40 comprises the tooth 102 and a shaft stub 104, and it can be seen that the tooth 102 and the shaft stub 104 are integrally formed, that is, made from a single part. Through the shaft stub 104, the drive gear 40 is mounted to the axle housing 80 so that it can rotate around the gear rotation axis 86, and here the shaft stub 104, and therefore the drive gear 40, is mounted to the axle housing 80 so that it can rotate via two bearings 106 and 108. The bearings 106 and 108 are designed here as rolling bearings, in particular as ball bearings. The bearings 106 and 108 are arranged in axial order of the drive gear 40 and are particularly spaced apart from each other. There, a spacer element 110 is provided, formed separately from the drive gear 40, and therefore separately from the shaft stub 104, and separately from the teeth 102. The spacer element 110 is designed as a ring and surrounds the drive gear 40 so as to completely encircle at least the longitudinal range of the shaft stub 104 in the circumferential direction. The spacer element 110 is positioned in the axial direction of the drive gear 40 between the bearings 106 and 108, particularly between the inner rings of the bearings 106 and 108, and the spacer element 108 holds the bearings 106 and 108, particularly their inner rings, spaced apart from each other in the axial direction of the drive gear 40. The spacer element 110, formed separately from the drive gear 40, and therefore separately from the shaft stub 104, and separately from the teeth 102, is coupled to the shaft stub 104, and therefore to the drive gear 40, particularly permanently, so as not to rotate relative to each other, for example, by pressing the spacer element 110 against the shaft stub 104, and therefore to the drive gear 40.

[0055] Figure 9 shows a structural unit 112 including a sensor element 94 and a spacer element 110. The sensor element 94 is formed separately from the drive gear 40 and is coupled to the drive gear 40, in particular permanently, so as not to rotate relative to each other. The sensor element 94 is formed separately from the spacer element 110 and is positioned on the spacer element 110 and coupled to the spacer element 110, in particular permanently, so as not to rotate relative to each other. In the embodiment shown in the figure, the sensor element 94 is formed as a ring and surrounds the drive gear 40 so as to completely encircle at least the respective longitudinal ranges of the spacer element 110 and the shaft stub 104 in the circumferential direction. For example, the sensor element 94 formed separately from the drive gear 40 and the spacer element 110 is coupled to the spacer element 110 by press-fit, in particular permanently, so as not to rotate relative to each other. The sensor element 94 is coupled to the drive gear 40, in particular permanently, so as not to rotate relative to each other, via the spacer element 110. The axial direction of the drive gear 40 coincides with the gear rotation axis 86, as indicated by arrow 114.

[0056] As can be seen particularly clearly from Figure 6, the receiving element 92, and therefore the rotational speed sensor 88, is equipped with a connecting device 116, by which the rotational speed sensor 88 can be electrically connected to or connected to wiring (not shown) formed separately from the rotational speed sensor 88. The receiving element 92 can, for example, provide an electrical signal characterizing the rotational speed of the drive gear 40 detected by the rotational speed sensor 88. Preferably, the electrical signal can be electrically transmitted from the receiving element 92 to the wiring via the connecting device 116, and the wiring can, for example, send the signal to a computer (also called a control device) of the tandem axle 10. The wiring can provide the signal, and the computer can receive the signal provided by the wiring. Then, for example, the computer can operate the automobile, in particular the tandem axle 10, in response to the received signal, and in particular in response to the rotational speed of the drive gear 40 detected by the rotational speed sensor 88. As can be seen particularly clearly in Figure 7, the connecting device 116 is located outside the housing space 84, and therefore outside the axle housing 80, and therefore around the perimeter 118 of the axle housing 80. In particular, the connecting device 116 is located on the outer surface 122 of the axle housing 80, facing the perimeter 118 and away from the housing space 84 and the inner circumferential surface 82.

[0057] Figure 10 is a block diagram showing the operation method of the tandem axle 10. In particular, the tandem axle 10, for example in an automobile, is operated according to a control strategy. Blocks B1, B2, B3, and B4 in Figure 10 show different operating modes of the tandem axle 10. Furthermore, the arrows in Figure 10 indicate that the tandem axle 10 can be switched between different operating modes (simply called modes) B1, B2, B3, and B4, for example, an electronic computer switches modes according to the detected rotational speed of the drive gear 40. Operating mode B1 is the 6x4 traction mode, where the clutch 70 is engaged and the clutch devices 66 and 68 are coupled. For example, the clutch 70 is switched between engaged and unengaged states depending on the driving conditions, and each of the clutch devices 66 and 68 is switched between coupled and unengaged states depending on the driving conditions. Operating mode B1 is activated, for example, when particularly excessive slip is detected in the wheels 14 and 16 of the first axle 12. Operating mode B2 is, for example, a 6x2 ready mode, which is set in all driving situations where slip is dangerous. In the second operating mode B2, the clutch 70 is in a disengaged state, and the clutch devices 66 and 68 are in a engaged state. As shown by the arrows in Figure 10, it is possible to switch from operating mode B2 to operating mode B1 or operating mode B3. Operating mode B3 is a 6x2 mode, in which the clutch 70 is in a disengaged state, and the clutch devices 66 and 68 are in a released state. Operating mode B3 is switched in driving situations where the slip of each of the wheels 14 and 16 is not dangerous, for example, when the car is driving on a highway.

[0058] Operating mode B4 is a synchronous mode for switching to, for example, operating mode B1 or operating mode B2. In operating mode B4, clutch 70 is engaged, and clutch devices 66 and 68 are disengaged. For example, switching from operating mode B3 to operating mode B1 via operating mode B4. For example, switching from operating mode B1 to operating mode B2, or vice versa. For example, switching from operating mode B2 to operating mode B1 or operating mode B3. For example, switching from operating mode B1 to operating mode B3 or operating mode B2. For example, switching from operating mode B3 to operating mode B4, or from operating mode B4 to operating mode B3 or operating mode B1. For example, to switch from operating mode B3 to operating mode B2 or operating mode B1, for example, switch from operating mode B3 to operating mode B1 via operating mode B4, and for example, as needed, switch from operating mode B1 to operating mode B2.

[0059] Figure 4 shows that the axle housing 80 is equipped with at least one mounting element 120, and the mounting element 120 mounts the receiving element 92 within the axle housing 80 in such a way that it can be removed in a particularly non-destructive manner. [Explanation of Symbols]

[0060] 10 Tandem Axle 12. First axle 14 wheels 16 wheels 18 Double arrow 20. Second axle 22 wheels 24 wheels 26 Double arrow 28 Double arrow 30 First differential gear 32 First drive shaft 34. Second differential gear 36. Second drive shaft 38 First drive gear 40 Second drive gear 42 Input Gears 44 Input Gear 46 Differential Housing 48 Differential Housing 50 Balance Gear 52 Balance Gear 54 Output Gear 56 output gears 58 Side Shaft 60 Side Shaft 62 Side Shaft 64 Side Shaft 66 Clutch device 68 Clutch device 70 Clutch 72 Third drive gear 74. Fourth drive gear 76 input elements 78 Output Elements 80 Axle Housing 82 Inner surface 84 Containment space 86 Gear rotation shaft 88 Rotation speed sensor 90 connecting elements 92 Receiving element 94 Sensor elements 96 recess 98 Partial area 100 Double-headed arrow 102 Teeth 104 Shaft Stub 106 bearings 108 Bearings 110 Spacer element 112 Structural Units 114 Double arrow 116 Connection device 118 Surroundings 120 mounting elements 122 Outside

Claims

1. A tandem axle (10) for an automobile, —The tandem axle (10) includes a drivable first axle (12), and the first axle (12) is ○Equipped with a first differential gear (30), the first wheels (14, 16) of the first axle (10) can be driven via the first differential gear (30), ○Equipped with a first drive shaft (32), the first differential gear (30) is driveable by the first drive shaft (32), and the first wheels (14, 16) are driveable via the first differential gear (30), —The tandem axle (10) is equipped with a drivable second axle (20), and the second axle (20) is ○A second differential gear (34) is provided, and the second wheels (22, 24) of the second axle (20) can be driven via the second differential gear (34), ○Equipped with a drive gear (40), the drive gear (40) is capable of driving the second differential gear (34), and the second wheels (22, 24) are capable of driving via the second differential gear (34), ○A second drive shaft (36) is provided, and the drive gear (40) can be driven by the second drive shaft (36), —The tandem axle (10) is equipped with a clutch (70), and the clutch (70) is ○The second drive shaft (36) is coupled to the first drive shaft (32) by the clutch (70) to transmit torque, thereby creating a coupled state in which the second drive shaft (36) can be driven by the first drive shaft (32) via the clutch (70). ○The second drive shaft (36) is switchable between a separated state and a state in which it is separated from the first drive shaft (32). In the tandem axle (10), —The second axle (20) comprises an axle housing (80), and the drive gear (40) rotatable relative to the axle housing (80) is housed within the axle housing (80), —A rotational speed sensor (88) is provided to detect the rotational speed of the drive gear (40), and the rotational speed sensor (88) ○The detection element (92) attached to the axle housing (80), ○The drive gear (40) and a sensor element (94) are connected so as not to rotate relative to each other, and the rotational speed of the sensor element (94) can be detected by a receiving element (92), thereby the rotational speed of the drive gear (40) can be detected by the rotational speed sensor (88). Tandem axle (10).

2. The sensor element (94) is formed separately from the drive gear (40) and is connected to the drive gear (40) so as not to rotate relative to each other. The tandem axle (10) according to claim 1.

3. The drive gear (40) comprises a toothed portion (102) and a shaft stub (104) integrally formed with the toothed portion (102), and the sensor element (94) is provided on the shaft stub (104). The tandem axle (10) according to claim 1 or 2.

4. The sensor element (94) is characterized in that it at least partially surrounds the shaft stub (104) in the circumferential direction (100) of the shaft stub (104), The tandem axle (10) according to claim 3.

5. —A spacer element (110), formed separately from the drive gear (40), is connected to the drive gear (40) so as not to rotate relative to it, and the spacer element (110) holds two bearings (106, 108) that rotatably mount the drive gear (40) to the axle housing (80) at a distance from each other in the axial direction (114) of the drive gear (40). —The sensor element (94), formed separately from the drive gear (40) and the spacer element (110), is connected to the spacer element (110) so as not to rotate relative to each other, and is connected to the drive gear (40) via the spacer element (110) so as not to rotate relative to each other. A tandem axle (10) according to any one of claims 1 to 4.

6. The sensor element (94) is characterized in that it at least partially surrounds the spacer element (110) in the circumferential direction (100) of the drive gear (40). The tandem axle (10) according to claim 5.

7. The spacer element (110), formed separately from the drive gear (40), the shaft stub (104), and the teeth (102), is connected to the shaft stub (104) so ​​as not to rotate relative to each other, and completely surrounds the shaft stub (104) in the circumferential direction (100) of the shaft stub (104), characterized in that A tandem axle (10) according to claim 5 or 6, dependent on claim 3 or 4.

8. The rotational speed sensor (88) is equipped with a connection device (116) that can electrically connect or connect the rotational speed sensor (88) to at least one wiring, and the connection device (116) is positioned outside the axle housing (80). A tandem axle (10) according to any one of claims 1 to 7.

9. An automobile equipped with a tandem axle (10) according to any one of claims 1 to 8.

10. A method of driving an automobile equipped with a tandem axle (10), —The tandem axle (10) includes a drivable first axle (12), and the first axle (12) is ○Equipped with a first differential gear (30), the first wheels (14, 16) of the first axle (12) can be driven via the first differential gear (30), ○Equipped with a first drive shaft (32), the first differential gear (30) is driveable by the first drive shaft (32), and the first wheels (14, 16) are driveable via the first differential gear (30), —The tandem axle (10) is equipped with a drivable second axle (20), and the second axle (20) is ○A second differential gear (34) is provided, and the second wheels (22, 24) of the second axle (20) can be driven via the second differential gear (34), ○Equipped with a drive gear (40), the drive gear (40) is capable of driving the second differential gear (34), and the second wheels (22, 24) are capable of driving via the second differential gear (34), ○A second drive shaft (36) is provided, and the drive gear (40) can be driven by the second drive shaft (36), —The tandem axle (10) is equipped with a clutch (70), and the clutch (70) is ○The second drive shaft (36) is coupled to the first drive shaft (32) by the clutch (70) to transmit torque, thereby creating a coupled state in which the second drive shaft (36) can be driven by the first drive shaft (32) via the clutch (70). ○The second drive shaft (36) is switchable between a separated state and a state in which it is separated from the first drive shaft (32). In terms of driving methods, —The second axle (20) comprises an axle housing (80), and the drive gear (40) rotatable relative to the axle housing (80) is housed within the axle housing (80), —A rotational speed sensor (88) is provided to detect the rotational speed of the drive gear (40), and the rotational speed sensor (88) ○The detection element (92) attached to the axle housing (80), ○The drive gear (40) and a sensor element (94) are connected so as not to rotate relative to each other, and the rotational speed of the sensor element (94) is detected by a receiving element (92), thereby the rotational speed of the drive gear (40) is detected by the rotational speed sensor (88). —The automobile is operated according to the rotational speed of the drive gear (40) detected by the rotational speed sensor (88), Driving method.

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