Vehicle transmission with a feed wheel for lubricating oil supply

Abstract

Vehicle transmission (1) with a conveyor wheel (8) for supplying lubricating oil, wherein the conveyor wheel (8) is arranged on an output shaft (3) of the vehicle transmission (1) and is driven by the output shaft (3), wherein the conveyor wheel (8) is mounted in the vehicle transmission (1) in such a way that it is decoupled from tilting movements of the output shaft (3), characterized in that the conveyor wheel (8) has recesses (12) for receiving lubricating oil, and that the recesses (12) each have at least one vent hole (28).

Description

[0001] The present invention relates to a vehicle transmission with a conveyor wheel for supplying lubricating oil.

[0002] DE 10 2016 212 369 A1 discloses a vehicle transmission with a drive shaft, an output shaft, and a feed wheel for supplying lubricating oil. The feed wheel is mounted on the output shaft of the vehicle transmission. The feed wheel supplies lubricating oil to an output shaft bearing, particularly when a primary lubrication device driven by the drive shaft is not driven. In practice, it has been shown that the lubricating oil supply from the feed wheel is insufficient during certain operating phases.

[0003] DE 10 2010 061 896 A1 discloses a transmission with an oil pump, wherein the oil pump can be arranged on an output shaft. The oil pump has a drive element, for example, a pump impeller, which is connected to the output shaft via drive elements. The drive elements establish a positive rotary connection between the transmission shaft and the drive element of the pump, and center the drive element on the transmission shaft.

[0004] Furthermore, DE 39 24 071 A1 discloses a rotary pump for gears in which a vane-type rotor is driven by a gear shaft via drive pins. The vane-type rotor is mounted on a shaft end in a largely free-floating manner, both radially and axially.

[0005] Finally, DE 102 24 875 A1 discloses a shaft-hub connection for transmitting a torque between a shaft and a hub by means of at least one driver element, whereby this shaft-hub connection can also be used in pumps.

[0006] It is the object of the present invention to provide a vehicle transmission with an improved lubricating oil supply.

[0007] This object is achieved by a vehicle transmission having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0008] A vehicle transmission with a feed wheel for supplying lubricating oil is proposed, wherein the feed wheel is arranged on an output shaft of the vehicle transmission and is driven by the output shaft. Arranged on the output shaft means that the feed wheel is arranged at least substantially concentrically to the output shaft. The output shaft can be passed through a central opening in the feed wheel. The feed wheel, which is driven in rotation by the output shaft, dips into an oil sump in the vehicle transmission at least in the region of its outer circumference and feeds oil from the oil sump to at least one bearing point in the vehicle transmission. This ensures a supply of lubricating oil to the bearing point when the output shaft rotates, regardless of the speed of a drive shaft of the vehicle transmission.The impeller thus pumps oil from an oil inlet located at the bottom of the oil sump to an oil outlet located at the top of the impeller, from where the oil flows to at least one bearing. The impeller can therefore also be referred to as a pump impeller. This bearing is preferably an output shaft bearing, which supports the output shaft in a transmission housing of the vehicle's transmission.

[0009] During certain operating phases, the input shaft of the vehicle's transmission is stationary and decoupled from the output shaft, even though the vehicle is moving. For example, when the vehicle is being towed. When the input shaft is stationary, a lubrication device in the vehicle's transmission driven by the input shaft is also deactivated. The output shaft, which is decoupled from the input shaft, is driven from the output side when the vehicle is towed. To prevent damage to an output shaft bearing, it must therefore also be supplied with lubricating oil during towing.

[0010] According to the present invention, the conveyor wheel is mounted in the vehicle transmission in such a way that it is decoupled from tilting movements of the output shaft. This means that although the conveyor wheel is driven by the rotating output shaft, the aforementioned tilting movements of the output shaft are not transmitted to the conveyor wheel. The output shaft is mounted in a transmission housing by means of at least one output shaft bearing, for example by means of a rolling bearing. A certain amount of play is present and necessary in the output shaft bearing, which causes tilting movements of the output shaft relative to the bearing and the transmission housing. The tilting movements are caused during operation by forces and load moments on the output shaft. A conveyor wheel rigidly connected to the output shaft inevitably undergoes the described tilting movements.Even minimal tilting movements in the area of ​​the output shaft's rotational axis cause significant movements on the outer circumference of the conveyor wheel as the radial distance from the rotational axis increases. Consequently, relatively large axial and radial clearances are required between the conveyor wheel, which is rigidly mounted on the output shaft, and adjacent components of the vehicle transmission to prevent collisions between the conveyor wheel and adjacent components.

[0011] Recesses or pockets are arranged around the outer circumference of the impeller to hold the oil to be pumped. In practice, it has been found that the required large spacing results in insufficient pumping performance of the impeller because oil escapes from the recesses through the relatively large gaps on the outer circumference of the impeller before it has been pumped to the designated oil outlet point. Particularly at high speeds, high pressure in the recesses for holding the oil causes a significant portion of the oil entrained from the oil sump to flow out of the recesses of the impeller and escape through the gaps with the aforementioned large spacing.

[0012] The decoupling of the impeller according to the invention now makes it possible to reduce the aforementioned distances between the impeller and the adjacent components without causing collisions. This significantly increases the pumping performance of the impeller because the gap leaks described above are significantly reduced. The bearings can thus be adequately supplied with oil across the entire speed range.

[0013] The aforementioned decoupling of the conveyor wheel from the output shaft can be achieved by connecting the conveyor wheel to the output shaft via a positive connection with a certain amount of play. In other words, this can be described as a floating bearing of the conveyor wheel on the output shaft. The connection between the output shaft and the conveyor wheel provides sufficient axial and radial play to allow the rotating conveyor wheel to center itself during operation, independent of tilting movements of the output shaft. The radial and axial play are dimensioned such that the conveyor wheel has sufficient freedom of movement to be decoupled from the tilting movements of the output shaft.

[0014] In one embodiment of the invention, a drive element is rigidly attached to the output shaft, and the conveyor wheel is connected to the drive element via a positive connection with play. The drive element can be designed, in particular, in annular or disc-shaped form and, for example, referred to as an intermediate ring. The drive element drives the conveyor wheel as the output shaft rotates. In this way, the conveyor wheel is reliably driven as soon as the output shaft rotates. The drive element can be manufactured separately from the output shaft and then firmly connected to the output shaft, for example, by screwing. The separately manufactured drive element enables simpler design and manufacture of the output shaft and easier assembly of the vehicle transmission.

[0015] According to one embodiment, the driving element can have at least one bore, with at least one pin rigidly connected to the conveyor wheel extending into the bore. Sufficient play exists between the at least one pin and the associated bore to decouple the conveyor wheel from the tilting movements of the output shaft. Preferably, several bores are arranged in the driving element and a corresponding number of pins are distributed around the circumference of the conveyor wheel. Due to the positive engagement between the pins and the bores, the conveyor wheel is reliably driven by the rotating output shaft.

[0016] According to the invention, the conveyor wheel has recesses for receiving lubricating oil, each of which has at least one vent hole. The vent holes can minimize an increase in air pressure in the recesses, allowing the oil to more easily reach the recesses rotating with the conveyor wheel. An increase in air pressure in the recesses is noticeable due to rotation, especially at high speeds. This measure can further increase the pumping performance of the conveyor wheel.

[0017] With a view to a compact design and a simple construction of the vehicle transmission, it can be provided that the feed wheel is arranged in a recess in an output cover of the vehicle transmission. The shape of the recess can be adapted to the outer contour of the feed wheel. For example, the recess has a geometrically similar shape to the outer contour of the feed wheel, on which the recesses for receiving the oil are arranged. In particular, the output cover can have a cylindrical recess in which the feed wheel is arranged with a likewise cylindrical outer contour. The recess thus forms an annular wall within which the feed wheel moves. During operation, a hydrostatic lubricating film forms in the gap between the outer contour of the feed wheel and the annular wall, which prevents wear and seizure of the components.

[0018] An output cover is the part of a vehicle transmission that closes off the output side of the transmission housing and houses the output shaft. The arrangement of the drive gear directly in the output cover enables a simple and compact design.

[0019] In the following, the invention and its advantages are explained in more detail with reference to the embodiment shown in the attached figures.

[0020] Showing: Fig. 1 is a schematic representation of a drive train equipped with a vehicle transmission according to the invention; Fig. 2 shows a section of a vehicle transmission according to the invention in a sectional view in a first sectional plane in the radial viewing direction; Fig. 3 shows a further section of the vehicle transmission according to the invention in a sectional view in a second sectional plane in the radial direction of view and Fig. 4 shows a further section of the vehicle transmission according to the invention in a sectional plane in the axial direction.

[0021] The one in the Fig. The drive train shown in Figure 1 is driven by a drive motor 13, for example, an internal combustion engine. An engine output shaft 14 of the drive motor 13 is connected to a drive shaft 2 of the vehicle transmission 1. In some embodiments, a starting clutch can also be arranged between the engine output shaft 14 and the drive shaft 2 of the vehicle transmission 1.

[0022] In a transmission housing 5 of the vehicle transmission 1, cooperating transmission elements 4 are arranged to realize different transmission ratios between the input shaft 2 and the output shaft 3. For the sake of clarity, these transmission elements 4 are shown in Fig. 1 is shown only as a rectangle. The output shaft 3 is mounted in the gearbox housing 5 by means of an output shaft bearing 6.

[0023] The output shaft 3 drives a wheel axle 16 of the vehicle, in this case a rail vehicle, via an axle drive 15. Two rail wheels 17 and 18 are attached to the wheel axle 16, which drive and propel the rail vehicle along the rails.

[0024] The vehicle transmission 1 comprises a clutch 7, with which a drive connection between the transmission elements 4 and the output shaft 3 can be selectively established or separated. Fig. The clutch 7 symbolically represented in Figure 1 has three switching positions and is shown in a neutral, middle switching position. In this neutral switching position, the drive connection is interrupted, i.e., separated. In the other two switching positions, a drive connection is established between the transmission elements 4 and the output shaft 3.

[0025] A lubricating device 22 is arranged on the drive side of the vehicle transmission 1. The lubricating device 22 is designed as a pressure lubrication device and comprises an oil pump 19, which is driven via the drive shaft 2. The oil pump 19 can be driven either directly by the drive shaft 2 or via another shaft in the vehicle transmission 1. The oil pump 19 sucks lubricating oil from the oil sump 10 through a suction line 20 and delivers it via pressure lines 21 to various lubrication points in the vehicle transmission 1. There are operating phases in which the drive shaft 2 is stationary, the vehicle is moving, and the output shaft 3 is rotating. This is the case, for example, when the vehicle is towed. The drive connection between the drive shaft 2 and the output shaft 3 is disconnected during such an operating phase. When the drive shaft 2 is stationary, the lubricating device 22, which can be driven by the drive shaft 2, is out of operation. The rotating output shaft 3 orHowever, their output shaft bearings 6 must continue to be supplied with lubricating oil to avoid damage to the output shaft bearing 6. This lubricating oil supply is provided by a feed wheel 8.

[0026] The feed wheel 8 is arranged on the output shaft 3. The feed wheel 8 can supply the output shaft bearing 6, at least temporarily, with lubricating oil from an oil sump 10. The oil sump 10 forms an oil level 9 on its surface in the gearbox housing 5. The oil level 9 is set such that at least the outer circumference of the feed wheel 8 is immersed in the oil sump 10, so that when the feed wheel 8 rotates, lubricating oil is entrained, i.e., pumped, from the oil sump 10. When the output shaft 3 rotates, the feed wheel 8, which rotates with the output shaft 3, pumps lubricating oil upwards, from where it reaches the output shaft bearing 6.

[0027] In the Fig. 2 shows a section of the upper half of the vehicle transmission according to the invention. Fig. 3 and the Fig. 4 each show a different section of the same vehicle transmission in a different sectional plane, so that all elements of the invention described below are illustrated in at least one of the figures mentioned. The output shaft 3 is mounted in an output cover 34 of the transmission housing 5 by means of an output shaft bearing 6, rotatable about the rotation axis 30. The output cover 34 is part of the multi-part transmission housing 5. The output cover 34 closes off the transmission housing 5 on the output side. The output shaft bearing 6 is designed here as a double-row roller bearing. The output shaft bearing 6 is supported in the output cover 34 via a bearing bush 29. Outside the transmission housing 5, an output flange 24 is fastened to the output shaft 6. Within the transmission housing 5, an inner flange 23 of the output shaft 3 extends in the radial direction.The axial and radial directions in this document refer to the rotation axis 30 of the output shaft 3, unless expressly stated otherwise.

[0028] A driving element 11 in the form of an intermediate ring is screwed tightly to the inner flange 23. In the radially outer region of the driving element 11, bores 26 are arranged, into which pins 25 project in the axial direction. The pins 25 are firmly connected to the conveyor wheel 8. The conveyor wheel 8 is arranged in a recess 27 in the output cover 34. The conveyor wheel 8 is held in its position with a certain amount of play by the positive connection between the pins 25 and the bores 26. The play in the radial direction between the pins 25 and the bore wall in the bores 26 can be a few tenths of a millimeter, preferably between 0.1 and 0.3 millimeters. In the axial direction, the conveyor wheel 8 can also have a play of a few tenths of a millimeter. The axial play can preferably be between 0.2 and 0.5 millimeters.The axial play of the conveyor wheel 8 can be limited on one side by a surface in the recess 27 and on the opposite side by an end face of the driving element 11. The radial and axial play are dimensioned such that the conveyor wheel 8 has sufficient freedom of movement to be decoupled from the tilting movements of the output shaft 3.

[0029] During operation, an oil film forms in the gaps between the conveyor wheel 8 and the adjacent components, preventing wear and seizure of the components. During operation, the rotating conveyor wheel 8 essentially floats on the oil film within the specified radial and axial clearance, decoupling it from the output shaft 3.

[0030] Especially in Fig.Figure 4 shows how the recesses 12 for receiving the oil to be pumped are arranged on the outer circumference of the pumping wheel 8. Between each recess 12, a web 31 is arranged, which separates the individual recesses 12 from each other in the circumferential direction.

[0031] In the lower area of ​​the conveyor wheel 8, an inlet opening 32 is arranged, through which the lubricating oil in the oil sump 10 is fed to the recesses 12 on the conveyor wheel 8. In the upper area, there is a scraper 33 that extends close to the outer circumference of the conveyor wheel 8. The scraper 33 improves the pumping action of the rotating conveyor wheel 8 by directing the oil escaping from the recesses 12 to an oil drain. From there, the oil flows to the bearing(s).

[0032] A further improvement in the pumping effect is provided by vent holes 28 arranged at the recesses 12. In the present exemplary embodiment, a vent hole 28 is arranged at each recess 12. The vent holes 28 extend in the axial direction from the respective recess 12 and open into the interior of the vehicle transmission 1. The vent holes 12 ensure that the oil from the inlet opening 32 flows more easily into the rotating recesses 12 because an increase in air pressure in the recesses is minimized. The vent holes 28 therefore also contribute to an increase in pumping performance. Reference symbol 1 vehicle transmission 2 drive shaft 3 Output shaft 4 transmission elements 5 Gearbox housing 6 output shaft bearings 7 clutch 8 conveyor wheel 9 Oil level 10 Oil sump 11 Driving element 12 recesses 13 Drive motor 14 Engine output shaft 15 axle drives 16 Wheel axle 17 Rail wheel 18 rail wheel 19 Oil pump 20 suction line 21 Pressure line 22 Lubrication device 23 inner flange 24 Output flange 25 pens 26 Hole 27 Deepening 28 vent hole 29 Bearing bush 30 Rotation axis 31 jetty 32 Inlet opening 33 scrapers 34 Output cover

Claims

[1] Vehicle transmission (1) with a conveyor wheel (8) for supplying lubricating oil, wherein the conveyor wheel (8) is arranged on an output shaft (3) of the vehicle transmission (1) and is driven by the output shaft (3), wherein the conveyor wheel (8) is mounted in the vehicle transmission (1) in such a way that it is decoupled from tilting movements of the output shaft (3), characterized by that the conveyor wheel (8) has recesses (12) for receiving lubricating oil, and that the recesses (12) each have at least one vent hole (28). [2] Vehicle transmission (1) according to claim 1, characterized by that the conveyor wheel (8) is connected to the output shaft (3) via a positive connection with play. [3] Vehicle transmission (1) according to claim 2, characterized by that a driving element (11) is rigidly fastened to the output shaft (3), and that the conveyor wheel (8) is connected to the driving element (11) via the positive connection with play. [4] Vehicle transmission (1) according to claim 3, characterized by that the driving element (11) has at least one bore (26), and that at least one pin (25) rigidly connected to the conveyor wheel (8) projects into the bore (26). [5] Vehicle transmission (1) according to one of the preceding claims, characterized by that the conveyor wheel (8) is arranged in a recess (27) in an output cover (34) of the vehicle transmission (1). [6] Vehicle transmission (1) according to claim 5, characterized by that the recess (27) has a geometrically similar shape to the outer contour of the conveyor wheel (8).

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