Transmission for a forklift truck as well as forklift truck with the transmission

Abstract

Gearbox (8) for a forklift truck (1), with a gearbox housing (13) that can be pivoted about a vertical pivot axis (S) on a vehicle frame (12) of the industrial truck (1), with an input shaft (15) for the drive-related connection of a drive machine (7), with an output shaft (16) for the drive-related connection of a vehicle wheel (6), with an intermediate shaft (19) arranged between the input shaft (15) and the output shaft (16), wherein the intermediate shaft (19) is connected to the input shaft (15) via a first gear stage (G1) and to the output shaft (16) via a second gear stage (G2), wherein the intermediate shaft (19) has an input-side output gear section (22) of the first gear stage (G1) and an output-side drive gear section (25) of the second gear stage (G2), wherein at least the input-side output gear section (22) is designed as a separate output gear which is positively and / or frictionally connected to the intermediate shaft (19), with an input-side and an output-side intermediate shaft bearing (35a, 35b) for rotatably supporting the intermediate shaft (19), wherein the two intermediate shaft bearings (35a, 35b) each have an inner ring (37), an outer ring (38) and several rolling elements (39) arranged to roll between the inner ring (37) and the outer ring (38), wherein the input-side output gear section (22) is arranged axially with respect to an intermediate shaft rotation axis (A3) between the two intermediate shaft bearings (35a, 35b), wherein the input-side intermediate shaft bearing (35a) is supported in a radial direction (RR) on the input-side output gear section (22) and in a radial opposite direction (RG) on the gearbox housing (13), and wherein the output-side intermediate shaft bearing (35b) is supported in the radial direction (RR) on the gearbox housing (13) and in the radial opposite direction (RG) is supported on the intermediate shaft (19), characterized by the fact that the input-side output gear section (22) and the output-side drive gear section (25) are supported against each other in the axial direction with respect to the intermediate shaft rotation axis (A3) via the inner ring (37) of the output-side intermediate shaft bearing (35b).

Description

[0001] The invention relates to a transmission for a forklift truck with the features of the preamble of claim 1. The invention further relates to a forklift truck with the transmission.

[0002] Industrial trucks are often powered by steerable drives, which are rotatably connected to the truck via a slewing ring bearing and can execute steering movements of 360 degrees or more on a steerable wheel of the truck. Two-stage gear drives are typically used to translate the drive torque to the wheel, with the first stage usually being a spur gear and the second a bevel gear. These drives are characterized by a very compact design and high torque density.

[0003] German patent application DE 102014 225 139 A1 discloses a drive unit for a forklift truck, comprising at least one gearbox housing, wherein the gearbox housing encloses a first gearbox stage designed as a reduction stage and a second gearbox stage, wherein the first gearbox stage consists of a motor pinion and an internally toothed spur gear meshing with the motor pinion, and wherein the second gearbox stage consists of a ring gear and a bevel gear meshing with the ring gear. A bevel gear shaft is guided through a central opening of the spur gear and is rotationally fixed to the spur gear, wherein a first and a second support bearing of the bevel gear shaft are arranged on both sides of the spur gear along the bevel gear shaft.

[0004] The publication EP 1 285 803 A1 discloses a single-wheel drive, in particular for industrial trucks, comprising a gearbox housing with at least one gear stage, a flanged drive motor, and a driven wheel, wherein the wheel is directly and rotationally fixed to a gear wheel and the gear wheel is rotatably mounted on a coaxially located, internal, and stationary spacer element. The gearbox is designed as a two-stage unit, with a first gear stage featuring spur gear teeth being associated with the drive motor, while a second gear stage featuring bevel gear teeth is associated with the wheel. The two gear stages are connected by a drive shaft mounted in the housing.

[0005] The invention is based on the objective of proposing a gearbox of the type mentioned above, which is characterized by a compact design and a robust construction.

[0006] This problem is solved by a transmission with the features of claim 1 and a forklift truck with the features of claim 15. Further embodiments and advantages of the invention will become apparent from the corresponding dependent claims, the following description, and the accompanying figures.

[0007] The invention relates to a transmission designed and / or suitable for use in a forklift truck. The transmission's primary function is to transmit drive torque to a wheel of the forklift truck. For this purpose, an electric drive motor is connected to the wheel via the transmission. The drive motor is located on the input side (drive side), and the wheel is located on the output side (drive side) of the transmission. Specifically, the transmission has a gear ratio of i > 1. In other words, the transmission reduces the speed and increases the transmitted torque.

[0008] The electric drive unit is designed to transmit electric drive torque to the vehicle wheel in drive mode and electric braking torque in generator mode. In drive mode, the drive unit is primarily used as an electric motor, drawing electrical energy from an energy storage device and converting it into mechanical power to apply drive torque to the vehicle wheel. In generator mode, the drive unit is primarily used as a generator, converting mechanical energy into electrical energy via recuperation to apply electric braking torque to the vehicle wheel. In generator mode, the recovered electrical energy is fed back into the energy storage device.

[0009] The gearbox comprises a gearbox housing that can be pivotally mounted to the vehicle frame of the industrial truck about a vertical pivot axis. In particular, the gearbox housing is pivotally mounted to the vehicle frame about the pivot axis via a slewing ring bearing. Specifically, the vehicle wheel is designed as a steerable wheel, which can be driven or braked by the drive unit depending on the driving situation and can be pivoted about the pivot axis by the gearbox housing to execute a steering movement. Preferably, the vehicle wheel has a steering angle of more than 180 degrees, preferably more than 360 degrees. In particular, "vertical" with respect to the pivot axis is to be understood as meaning that the pivot axis, in the installed state of the gearbox, is oriented vertically, preferably substantially perpendicular, to a floor plane.Preferably, the vehicle wheel defines a wheel axis of rotation around which the vehicle wheel rotates during operation. Particularly preferably, the wheel axis of rotation is horizontal, preferably aligned with the ground plane. The drive motor is arranged coaxially to the pivot axis. In particular, the drive motor comprises a stator and a rotor rotating around a machine axis of rotation, wherein the pivot axis is defined by the machine axis of rotation and / or the pivot axis and the machine axis of rotation are arranged coaxially. Preferably, the stator is rotationally fixed and / or stationary with respect to a vehicle frame. This allows the supply and signal lines for the electric motor to be permanently routed.

[0010] The gearbox has an input shaft on the input side, which is designed and / or suitable for connecting the drive motor. In particular, the input shaft is torque-transmitting, preferably rotationally fixed, and connected to a drive shaft, preferably a rotor shaft driven by the rotor, of the drive motor. Alternatively, however, the input shaft can also be formed by the drive shaft of the drive motor. Preferably, the input shaft is arranged coaxially with the pivot axis or the axis of rotation of the machine.

[0011] The transmission has an output shaft on the output side, which is designed and / or suitable for connecting the vehicle wheel to the drive system. In particular, the output shaft is connected to a drive shaft, preferably a wheel hub driving the vehicle wheel, in a torque-transmitting manner and preferably in a rotationally fixed manner. Alternatively, however, the output shaft can also be formed by the drive shaft, in particular the wheel hub. Preferably, the output shaft is arranged coaxially with the wheel's axis of rotation.

[0012] The transmission features an intermediate shaft located between the input and output shafts. Specifically, the intermediate shaft is aligned with the input shaft and / or perpendicular to the output shaft. The intermediate shaft is connected to the input shaft via a first gear stage, particularly on the input side, and to the output shaft via a second gear stage, particularly on the output side. The first gear stage serves primarily to create a center distance between the input shaft and the intermediate shaft. This center distance is necessary to position the intermediate shaft next to the vehicle wheel. The second gear stage serves primarily to redirect the drive torque from the intermediate shaft to the output shaft. The transmission can have exactly the first and second gear stages. Alternatively, however, the transmission can also have more than two gear stages.

[0013] The intermediate shaft has an input-side output gear section of the first gear stage and an output-side input gear section of the second gear stage. Specifically, the input-side output gear section is operatively connected to an input-side input gear section of the input shaft, transmitting torque. Similarly, the output-side input gear section is operatively connected to an output-side output gear section of the output shaft, transmitting torque. In principle, the input-side output gear section and / or the output-side input gear section of the intermediate shaft can be designed as separate components that are rotationally fixed to the intermediate shaft. For example, the input-side output gear section and / or the output-side input gear section can be rotationally fixed to the intermediate shaft via a positive connection, e.g., a splined connection, and / or a frictional connection, e.g., an interference fit.Alternatively, the input-side output gear section and / or the output-side drive gear section and the intermediate shaft can be manufactured in one piece, in particular from a common material section.

[0014] The transmission has an input-side and an output-side intermediate shaft bearing, which are designed and / or suitable for rotatably mounting the intermediate shaft in the transmission housing. In particular, the input-side intermediate shaft bearing is located on the input side of the transmission, preferably near the input-side output gear section. In particular, the output-side intermediate shaft bearing is located on the output side of the transmission, preferably near the output-side drive gear section.

[0015] Within the scope of the invention, it is proposed that the input-side output gear section is arranged axially between the two intermediate shaft bearings. In other words, the input-side output gear section is arranged within the intermediate shaft bearing, and the output-side drive gear section is arranged outside the intermediate shaft bearing. The input-side intermediate shaft bearing is supported radially on the input-side output gear section and radially against the gearbox housing. The output-side intermediate shaft bearing is supported radially on the gearbox housing and radially against the intermediate shaft. In particular, the radial direction and radially against are to be understood as referring to an intermediate shaft axis of rotation about which the intermediate shaft rotates during operation.

[0016] The invention is based on the understanding that the installation space available for the intermediate shaft bearing is limited and, depending on the gearbox design, is determined by the permissible circumscribed radius of the drive and / or by the required load-bearing capacity of the gear set of the second gearbox stage. Furthermore, the required service life is very long. In particular, the gear teeth and the output-side intermediate shaft bearing are the components that limit the service life. The connection between the intermediate shaft and the input-side output gear section is also subject to high loads. The invention is further based on the understanding that the output-side intermediate shaft bearing is located next to the vehicle wheel and cannot be made arbitrarily large with respect to its outer diameter. The inner diameter of this bearing is also limited, as the gear teeth of the intermediate shaft restrict its diameter in the bearing area.

[0017] The arrangement of intermediate shaft bearings according to the invention proposes a bearing arrangement for the intermediate shaft that can be designed to reliably meet the service life requirements and also provides sufficient installation space for the output-side drive gear section to achieve the required service life of the gear teeth. In particular, the bearing spacing and thus the effective bearing base between the two intermediate shaft bearings can be increased, which contributes to a longer service life of the intermediate shaft bearings. A gearbox is thus proposed that is characterized by a compact design and a robust construction.

[0018] In a specific embodiment, the input-side and output-side intermediate shaft bearings are each designed as rolling bearings. In particular, the two intermediate shaft bearings serve to absorb radial and / or axial forces with respect to the intermediate shaft's axis of rotation. According to the invention, the intermediate shaft bearings each have an inner ring and an outer ring, as well as several rolling elements arranged to roll between the inner and outer rings. In principle, the inner and / or outer rings can be designed as separate bearing rings, which are preferably frictionally connected to the respective bearing partner. Alternatively, however, the inner and / or outer ring of the input-side and / or output-side intermediate shaft bearing can also form an integral part of the associated bearing partner.The inner ring of the input-side intermediate shaft bearing is rotationally fixed to the gearbox housing, and the outer ring of the input-side intermediate shaft bearing is rotationally fixed to the input-side output gear section. Conversely, the inner ring of the output-side intermediate shaft bearing is rotationally fixed to the intermediate shaft, and the outer ring of the output-side intermediate shaft bearing is rotationally fixed to the gearbox housing. During operation, the inner ring of the output-side intermediate shaft bearing rotates while the outer ring remains stationary, whereas in the input-side intermediate shaft bearing, the outer ring rotates while the inner ring remains stationary. By supporting the input-side intermediate shaft bearing against the input-side output gear section, a particularly compact bearing arrangement is proposed, which also provides an increased bearing base even with short intermediate shafts.

[0019] In a further specification, it is provided that the input-side and output-side intermediate shaft bearings are each designed as angular contact bearings. Specifically, an angular contact bearing is understood to be a rolling bearing that serves to absorb axial and radial forces with respect to the intermediate shaft's axis of rotation. Preferably, both intermediate shaft bearings are designed as tapered roller bearings. Alternatively, however, both intermediate shaft bearings can also be designed as angular contact ball bearings or deep groove ball bearings.

[0020] In a further development, it is proposed that the pressure cones formed by the pressure lines of the two angular contact bearings are aligned axially with their pressure cone tips relative to the intermediate shaft's axis of rotation. The pressure lines are understood as force flow lines along which a load is transmitted from one bearing ring to the other via the rolling elements. Specifically, the pressure lines of each angular contact bearing define a pressure cone that determines the arrangement of the bearing sets, with the pressure lines intersecting at the pressure cone tips. In particular, the pressure lines of the two angular contact bearings are aligned. Thus, a bearing arrangement is proposed that serves both to absorb axial forces and to facilitate the simple assembly of the intermediate shaft.

[0021] In a further specific embodiment, it is provided that an axial force acting on the intermediate shaft in one axial direction can be supported in the gearbox housing by one intermediate shaft bearing, in particular the input-side bearing, and that an axial force acting on the intermediate shaft in the opposite axial direction can be supported in the gearbox housing by the other intermediate shaft bearing, in particular the output-side bearing. Specifically, the axial force acting on the input-side intermediate shaft bearing is transmitted from its outer ring to its inner ring. Specifically, the axial force acting on the output-side intermediate shaft bearing is transmitted from its inner ring to its outer ring. Thus, a bearing arrangement is proposed which, in addition to radial forces, can also absorb axial forces in both positive and negative directions with respect to the intermediate shaft's axis of rotation.

[0022] In a further specific embodiment, the input-side output gear section is provided with a bearing receptacle on its axial end face, in which the input-side intermediate shaft bearing is received. In particular, the bearing receptacle is designed as a cylindrical receptacle, preferably a recess or opening. The input-side intermediate shaft bearing can be positively and / or frictionally engaged in the bearing receptacle, at least in the radial direction. Specifically, the input-side intermediate shaft bearing is partially or completely countersunk in the bearing receptacle in the axial direction. Thus, a transmission is proposed which is characterized by a particularly compact design.

[0023] In a further specification, it is provided that the outer ring of the input-side intermediate shaft bearing is mounted in the bearing housing in a rotationally fixed manner. Specifically, the outer ring of the input-side intermediate shaft bearing is mounted in the bearing housing by a force-fit connection, particularly an interference fit. The outer ring of the input-side intermediate shaft bearing can be pre-assembled in the bearing housing. Alternatively, the outer ring of the input-side intermediate shaft bearing can also be integrated into the input-side output gear section by means of a running surface arranged in the bearing housing. Thus, a gearbox is proposed which is characterized by particularly simple assembly.

[0024] According to the invention, the input-side output gear section and the output-side drive gear section are supported against each other in the axial direction with respect to the intermediate shaft's axis of rotation by the output-side intermediate shaft bearing, in particular its inner ring. According to the invention, at least the input-side output gear section is designed as a separate output gear which is positively and / or non-positively connected to the intermediate shaft. In particular, the output gear is rotationally fixed to the intermediate shaft in the direction of rotation by means of a positive-locking contour, preferably a splined connection. Optionally, the output gear is secured in the axial direction by a locking element, preferably at least one lock nut or locking screw. Alternatively, the output gear can be connected to the intermediate shaft by means of an interference fit.The input-side output gear is preferably indirectly supported axially via a spacer element, preferably a cylindrical bushing, on the output-side intermediate shaft bearing, in particular its inner ring. Alternatively, the input-side output gear can also have a cylindrical hub section via which the output gear is directly supported on the output-side intermediate shaft bearing, in particular its inner ring.

[0025] In a further embodiment, the gearbox housing comprises a base body and a cover. In particular, the gearbox housing is designed in two parts. Preferably, the cover is pivotably mounted on the vehicle frame via the slewing ring bearing about the pivot axis, with the base body being rigidly connected to the cover, preferably by bolting. The base body has a first section for accommodating the first gear stage and a second section for accommodating the second gear stage. In particular, the first section is open axially with respect to the motor's axis of rotation, especially in the direction of the drive motor, and the second section is open axially with respect to the motor's axis of rotation, especially in the direction of the vehicle wheel.The first housing section is covered in the axial direction with respect to the intermediate shaft's axis of rotation by the housing cover, with the input-side intermediate shaft bearing being supported on the housing cover in the opposite axial direction. In particular, the housing cover is designed such that the input-side output gear section is rotatably mounted in or on the housing cover via the input-side intermediate shaft bearing in both the radial and axial directions.

[0026] In a further specification, it is provided that the housing cover has a support section which is designed and / or suitable for radially supporting the input-side intermediate shaft bearing. In particular, the input-side intermediate shaft bearing is positively and / or force-fitted to the support section at least in the radial opposite direction. Specifically, the support section is designed as a cylindrical section arranged coaxially and / or concentrically to the intermediate shaft. The intermediate shaft is received radially within the cylindrical section in sections, with the intermediate shaft rotating relative to the cylindrical section during operation. Specifically, the intermediate shaft is spaced radially from the cylindrical section by an annular gap. The input-side intermediate shaft bearing is preferably radially supported on an outer circumference of the cylindrical section.A gearbox housing is therefore proposed which is characterized by a compact design.

[0027] Alternatively, the support section can be designed as a cylindrical bore arranged coaxially and / or concentrically to the intermediate shaft. The cylindrical bore preferably serves to receive a bearing cap, with the inner ring of the input intermediate shaft bearing being received in the bearing cap. In this case, the bearing cap allows for adjustment of the bearing preload for both intermediate shaft bearings without having to remove the housing cover from the housing body.

[0028] In a further specific implementation, the inner ring of the input-side intermediate shaft bearing is mounted to the support section in a rotationally fixed manner. Specifically, the inner ring of the input-side intermediate shaft bearing is frictionally locked to the support section, particularly via an interference fit. Preferably, the inner ring of the input-side intermediate shaft bearing can be pre-assembled on the support section. Alternatively, the inner ring can also be integrated into the housing cover by means of a running surface arranged on the support section. Thus, a gearbox is proposed that is characterized by particularly simple assembly.

[0029] In a further development, the first gear stage is provided for by a spur gear transmission. Specifically, the spur gear transmission can optionally be designed as a friction-driven or positive-driven spur gear transmission. Designed as a friction-driven spur gear transmission, the first gear stage is preferably configured as a friction wheel transmission, also known as a rolling element transmission. In particular, the input-side drive and output gear sections are each designed as a friction wheel, which are in frictional contact with each other. Designed as a positive-drive spur gear transmission, the first gear stage is preferably configured as a gear transmission. In particular, the input-side drive and output gear sections are each designed as a gear, which mesh with each other. Alternatively, the first gear stage is formed by a traction element transmission.The traction drive can optionally be designed as a friction-based or positive-locking traction drive. In a friction-based traction drive, the first gear stage is preferably designed as a belt drive. In particular, the input-side drive and output gear sections are each designed as a pulley, which are frictionally connected to each other via a traction element to transmit torque. In a positive-locking traction drive, the first gear stage is preferably designed as a chain drive. In particular, the input-side drive and output gear sections are each designed as a toothed pulley, which are positively connected to each other via a traction element to transmit torque.

[0030] In a further embodiment, the second gear stage is formed by a bevel gear. Preferably, the bevel gear is designed as a single-stage bevel gear. In particular, a shaft angle of approximately or exactly 90 degrees is formed between the intermediate shaft and the output shaft. The bevel gear preferably serves to overcome the shaft angle between the intermediate shaft and the output shaft. In principle, the bevel gear is a bevel gear. In particular, a bevel gear is characterized by the fact that the axes of rotation of the intermediate shaft and the output shaft have a common point of intersection. Thus, a particularly cost-effective bevel gear is proposed. Alternatively, the bevel gear is a hypoid gear. In particular, a hypoid gear is characterized by the fact that the axes of rotation of the intermediate shaft and the output shaft are offset from each other or do not have a common point of intersection.For example, a positive axis offset can improve the smooth running and load-bearing capacity of the bevel gear. This results in a particularly robust bevel gear.

[0031] In a specific design embodiment, the output-side drive gear section is configured as a bevel pinion, which meshes with a ring gear that is non-rotatably connected to the output shaft. In particular, the intermediate shaft is designed as a bevel gear shaft. In principle, the bevel pinion can be designed as a separate component, which is non-rotatably connected to the intermediate shaft, e.g., via a splined connection. Preferably, the bevel pinion and the intermediate shaft are manufactured in one piece, particularly from a common section of material. In a bevel gear configuration, the bevel pinion and the ring gear each have straight, helical, or curved teeth. In a hypoid gear configuration, the bevel pinion and the ring gear each have curved teeth.

[0032] A further aspect of the invention relates to a forklift truck with the transmission as previously described or according to any one of claims 1 to 14. Preferably, the forklift truck has at least or exactly two axles and at least or exactly three wheels. In particular, the forklift truck has a drive unit comprising the drive motor, the transmission, and exactly one driven, steerable wheel. Specifically, the truck has a front axle with two front wheels and one rear wheel, the rear wheel being the driven, steerable wheel. Alternatively, the truck can have a rear axle with two wheels and one front wheel, the front wheel being the driven, steerable wheel.

[0033] The present invention will now be explained in more detail with reference to a drawing. It shows: Fig. 1 a schematic representation of a vehicle with a drive unit as an embodiment of the invention; Fig. 2 a sectional view of the drive unit for the vehicle according to Fig. 1; Fig. 3 a detailed view of the sectional representation of the Fig. 2.

[0034] Fig. Figure 1 shows a highly schematic representation of a vehicle 1 with a drive unit 2, which is configured to drive the vehicle 1. The vehicle 1 is a three-track industrial truck, e.g., a forklift, and has a front axle 3 with a first and a second front wheel 4, 5, and exactly one rear wheel, which forms a driven, steerable wheel 6 of the vehicle 1.

[0035] The drive unit 2 comprises an electric drive motor 7, which is connected to the driven, steerable vehicle wheel 6 via a two-stage gearbox 8. For example, the electric drive motor 7 is a three-phase asynchronous motor; however, other electric motors, such as synchronous motors, can also be used.

[0036] Vehicle 1 has an electrical energy storage device 9, which serves to provide and store electrical energy for the drive motor 7. The electrical energy storage device 9 is, for example, a battery or an accumulator. An inverter (not shown) is used to control the drive motor 7, which regulates the operating state of the drive motor 7 for the respective driving situation.

[0037] To move or accelerate the vehicle 1 in a forward or reverse direction V, R, the drive motor 7 operates in drive mode, converting the electrical energy supplied by the energy storage device 9 into mechanical energy. To decelerate the vehicle 1 in a forward or reverse direction V, R, the drive motor 7 operates in generator mode, converting mechanical energy into electrical energy and supplying it to the energy storage device 9.

[0038] Fig. Figure 2 shows the drive unit 2 in a sectional view as an embodiment of the invention. The drive machine 7 has a stator 10 and a rotor 11, wherein the rotor 11 rotates relative to the stator 10 about a machine axis of rotation A1. The stator 10 is rotationally fixed to a vehicle frame 12 of the vehicle 1, as shown in Figure 2. Fig. As shown in Figure 1, the drive machine 7 is connected. In its installed state, the drive machine 7 is arranged vertically, with the machine's axis of rotation A1 being substantially perpendicular to a floor plane E. The floor plane E is defined by a surface on which the vehicle wheel 6 (not shown) rests or rolls during operation. During operation, the vehicle wheel 6 rotates about a horizontal wheel axis of rotation A2, which is aligned parallel and / or in the same direction as the floor plane E. In particular, the machine axis of rotation A1 and the wheel axis of rotation A2 are oriented at an angle, preferably at right angles, to each other.

[0039] The gearbox 8 is designed as a two-stage gearbox and has a first gear stage G1 and a second gear stage G2. The two gear stages G1 and G2 are installed in a gearbox housing 13, which is rotatably connected to the vehicle frame 12 via a slewing ring bearing 14. The gearbox housing 13 is pivotable about the machine axis of rotation A1 of the drive machine 7, with the machine axis of rotation A1 thus defining a pivot axis S. This allows the drive unit 2 to be steered. For example, the gearbox housing 13 is connected to a steering drive (not shown), which transmits a pivoting movement about the pivot axis S to the gearbox housing 13. The steering angle can be arbitrary in this case, i.e., 360° or greater.

[0040] The transmission 8 has an input shaft 15 to form a transmission input and an output shaft 16 to form a transmission output. The input shaft 15 is connected to a drive shaft 17 of the drive machine 7, which, during operation, is driven by the rotor 11 around the machine's axis of rotation A1. For example, the input shaft 15 and the drive shaft 17 are manufactured as a single piece, e.g., from a single casting. The output shaft 16 is connected to an output shaft 18, designed as a wheel hub, which, during operation, drives the vehicle wheel 6 around the wheel's axis of rotation A2. For example, the output shaft 16 and the output shaft 18, or the wheel hub, are manufactured as a single piece, e.g., from a single casting.

[0041] The gearbox 8 has an intermediate shaft 19, which is arranged between the input shaft 15 and the output shaft 16. The intermediate shaft 19 is rotatably mounted in the gearbox housing 13 about an intermediate shaft axis of rotation A3, wherein the intermediate shaft axis of rotation A3 is parallel to the machine axis of rotation A1 and perpendicular, in particular perpendicular, to the wheel axis of rotation A2. The intermediate shaft 19 is mechanically connected to the input shaft 15 via the first gearbox stage G1 and to the output shaft 16 via the second gearbox stage G2. Thus, the first gearbox stage G1 forms an input-side gearbox stage and the second gearbox stage G2 a second-side gearbox stage. A torque path runs from the drive machine 7 via the first gearbox stage G1 to the intermediate shaft 19 and via the second gearbox stage G2 to the vehicle wheel 6.

[0042] The first gear stage G1 is formed by a spur gear transmission 20, wherein the spur gear transmission 20 has an input-side drive gear section 21 non-rotatably connected to the input shaft 15 and an input-side output gear section 22 non-rotatably connected to the intermediate shaft 19, which mesh with each other. In particular, the input-side drive gear and output gear sections 21 and 22 are each designed as a spur gear 23.

[0043] The second gear stage G2 is formed by a bevel gear 24, which has an output-side drive gear section 25 non-rotatably connected to the intermediate shaft 19 and an output-side output gear section 26 non-rotatably connected to the output shaft 16, and which mesh with each other. The output-side drive gear section 25 is designed as a bevel pinion 27 and the output-side output gear section 26 as a ring gear 28. The bevel gear 24 serves to redirect the torque path from the intermediate shaft 19 to the output shaft 16. The bevel gear 24 can optionally be configured as a bevel gear or a hypoid gear.

[0044] The gearbox housing 13 comprises a housing base 29 and a housing cover 30, the housing cover 30 being rotatably mounted on the vehicle frame 12 via the slewing ring bearing 14 and being rigidly bolted to the housing base 29. The housing base 29 has a first housing section 31 for receiving the first gear stage G1 and a second housing section 32 for receiving the second gear stage G2. The input shaft 15 and the drive shaft 17 of the drive motor 7 are formed in one piece and supported by a first bearing 33a and a second bearing 33b. The output shaft 16 is rotatably mounted in the second housing section 32 via a first and a second output shaft bearing 34a, 34b.

[0045] The intermediate shaft 19 extends from the first housing section 31 into the second housing section 32, and is rotatably mounted in the first housing section 31 via an input-side intermediate shaft bearing 35a and an output-side intermediate shaft bearing 35b. For example, the input shaft bearings 33a, 33b, the output shaft bearings 34a, 34b, and the intermediate shaft bearings 35a, 35b can be designed as rolling bearings.

[0046] Fig. Figure 3 shows a detailed view of the drive unit 2, specifically the intermediate shaft 19 as an embodiment of the invention. The intermediate shaft 19 is designed as a bevel gear shaft, with the output-side drive gear section 25, designed as a bevel pinion 27, and the intermediate shaft 19 being made from a common material section. The input-side output gear section 22, designed as a spur gear 23, is a helical gear arranged axially opposite the bevel pinion 27 with respect to the intermediate shaft's axis of rotation A3. The spur gear 23 is, for example, rotationally fixed to the intermediate shaft 19 by means of a splined connection and secured in an axial direction AR by two locking elements 36. Each of the two locking elements 36 is designed as a nut, with the intermediate shaft 19 having a corresponding external thread at its end for this purpose.

[0047] Typically, a tapered roller bearing in an O-arrangement is used to support the intermediate shaft 19, with both the spur gear teeth (input-side output gear section 22) and the bevel gear teeth (output-side input gear section 25) arranged axially outside the two bearing locations (intermediate shaft bearings 35a, 35b). The distance between the two bearing locations is defined by the distance between the bevel gear teeth and the spur gear teeth and can hardly be increased without increasing the distance between the gear teeth. Another disadvantage of the described solution lies in the need for axial securing of the connection between the intermediate shaft and the spur gear. This axial securing must also ensure the axial bearing preload and is usually achieved by a nut (locking device 36).The splined shaft profile is typically designed with a small amount of play, which can lead to slight movements of the spur gear on the intermediate shaft. This small amount of play is necessary for the assembly process; however, these movements can also create a loosening torque for the nut (locking element 36). To prevent the nut from loosening, additional securing measures are required. Since the overall height of the drive cannot be increased, the possible securing measures are limited to those that require a low profile. For example, the nut is secured with a thread-locking compound. Should the nut loosen, this can lead to total gearbox failure due to tooth breakage of the bevel gear teeth.

[0048] In an alternative implementation, the bearings (intermediate shaft bearings 35a, 35b) are arranged in an X-arrangement within the bevel gear teeth (output-side drive gear section 25) and the spur gear teeth (input-side output gear section 22). However, the inner diameter and width of the bearing, which is located on the bevel gear teeth of the bevel gear shaft, are relatively small because they are limited by the geometry of the bevel gear stage (second gear stage G2) and the bearing is situated on the smaller side of the truncated cone (pinion 27) of the bevel gear shaft (intermediate shaft 19). The outer diameter of the same bearing is limited by the geometry of the large bevel gear (ring gear 28). A compromise between the width of the bevel gear teeth and the outer diameter of the bearing can lead to a comparatively short service life of the transmission.

[0049] Therefore, according to Fig.3. A bearing arrangement for the intermediate shaft 19 is proposed in which the bevel pinion 27 is located below the two intermediate shaft bearings 35a, 35b, and the spur gear 23 is mounted on the intermediate shaft 19 between the two intermediate shaft bearings 35a, 35b. The input-side intermediate shaft bearing 35a is supported in a radial direction RR on the input-side output gear section 22 and in a radial opposite direction RG on the housing cover 30. The output-side intermediate shaft bearing 35b is supported in the radial direction RR on the housing base 29 and in the radial opposite direction RG on the intermediate shaft 19.

[0050] The two intermediate shaft bearings 35a, 35b are each designed as tapered roller bearings, each having an inner ring 37, an outer ring 38, and several rolling elements 39 (tapered rollers) arranged between the inner ring 37 and the outer ring 38. The intermediate shaft 19 carries the inner ring 37 of the output-side intermediate shaft bearing 35b. When the intermediate shaft 19 rotates about the intermediate shaft axis of rotation A3, the inner ring 37 of the output-side intermediate shaft bearing 35b also rotates with it. The outer ring 38 of the output-side intermediate shaft bearing 35b is received in the housing body 29 and does not rotate.

[0051] The spur gear 23 has a bearing receptacle 40 on its axial end face for receiving the input-side intermediate shaft bearing 35a. The housing cover 30 also has a support section 41 arranged coaxially with the bearing receptacle 40 for supporting the input-side intermediate shaft bearing 35a. The bearing receptacle 40 is designed as a cylindrical recess, and the support section 41 as a cylindrical projection, the cylindrical projection extending section by section into the recess. The outer ring 38 of the input-side intermediate shaft bearing 35a is received in the bearing receptacle 40. When the intermediate shaft 19 rotates about the intermediate shaft rotation axis A3, the outer ring 38 of the input-side intermediate shaft bearing 35a also rotates together with the spur gear 23 and the intermediate shaft 19. The inner ring 37 of the input-side intermediate shaft bearing 35a is mounted on an outer circumference of the support section 41 and does not rotate.The intermediate shaft 19 is arranged section by section radially within the support section 41 with the two locking devices 36.

[0052] Furthermore, a spacer element 42, e.g., a cylindrical bushing, is arranged between the spur gear 23 and the output-side intermediate shaft bearing 35b, wherein the spur gear 23 is supported in an axially opposite direction AG with respect to the intermediate shaft rotation axis A3 via the spacer element 42 on the inner ring 37 of the output-side intermediate shaft bearing 35b. The spacer element 42 defines an axial distance between the spur gear 23 and the output-side intermediate shaft bearing 35b.

[0053] Since the first gear stage G1 has helical teeth and the second gear stage G2 has spiral teeth, the intermediate shaft bearings 35a, 35b can be subjected to radial forces RR in the radial direction, axial forces AR in the radial direction, and axial forces AG in the opposite direction with respect to the intermediate shaft's axis of rotation A3. The pressure cones 43a, 43b of the two intermediate shaft bearings 35a, 35b point with their tips in the axial direction AR. Thus, neither a classic X-arrangement nor an O-arrangement is present. If a resultant axial force in the axial direction AR acts on the intermediate shaft 19, it is supported by the input-side intermediate shaft bearing 35a in the housing cover 30. If a resultant axial force in the axial opposite direction AG acts on the intermediate shaft 19, it is supported by the output-side intermediate shaft bearing 35b in the housing body 29.

[0054] The bearing pattern of the second gear stage 21 can be adjusted by inserting one or more shims (not shown) between the housing base 29 and the outer ring 38 of the output intermediate shaft bearing 35b. This allows the position of the intermediate shaft 19 relative to the ring gear 28 to be adjusted. The preload of the two intermediate shaft bearings 35a, 35b can be adjusted by inserting one or more shims (not shown) between the housing cover 30 and the inner ring 37 of the input intermediate shaft bearing 35a.

[0055] The proposed bearing arrangement allows for an increased effective bearing base (distance between the pressure cone tips of the tapered roller bearings) compared to known arrangements, since the input-side intermediate shaft bearing 35a is located above the spur gear 23. This proposes a bearing arrangement for the intermediate shaft 19 that reliably meets the service life requirements and also provides sufficient installation space for the bevel gear teeth. Furthermore, the output-side intermediate shaft bearing 35b is located above the bevel gear teeth of the pinion 27. This ensures that the size of this tapered roller bearing and the tooth width of the ring gear 28 (and thus the service life of both components) are not restricted.Furthermore, the intermediate shaft 19, the inner ring 37 of the output-side intermediate shaft bearing 35b, the spacer element 42, the spur gear 23, the locking elements 36, and the outer ring 38 of the input-side intermediate shaft bearing 35a can be pre-assembled outside the gearbox 8, which significantly simplifies the assembly of the gearbox 8. Another advantage is that the described bearing arrangement can also be implemented with a short intermediate shaft 19, where there is insufficient installation space to arrange both intermediate shaft bearings 35a and 35b between the bevel gear 27 and the spur gear 23. Reference sign 1 vehicle 2 Drive unit 3 Front axle 4 first front wheel 5 second front wheel 6 vehicle wheel 7 Drive machine 8 gearboxes 9 Energy storage 10 Stator 11 Rotor 12 vehicle frames 13 Gearbox housing 14 slewing ring bearings 15 Input wave 16 Output shaft 17 Drive shaft 18 Output shaft 19 Intermediate wave 20 spur gear units 21 Input-side drive wheel section 22 Input-side output gear section 23 Spur gear 24 angle gears 25 output-side drive wheel section 26 output side output gear section 27 conical pinions 28 ring gear 29 Housing base 30 Case Covers 31 first housing section 32 second housing section 33a first input shaft bearing 33b second input shaft bearing 34a first output shaft bearing 34b second output shaft bearing 35a Input-side intermediate shaft bearing 35b output-side intermediate shaft bearing 36 safety devices 37 inner ring 38 Outer ring 39 rolling elements 40 Bearing intake 41 Support section 42 spacer elements 43a Inlet-side pressure cone 43b outlet-side pressure cone Axle spacing A1 Machine rotary axis A2 Wheel pivot axis A3 Intermediate shaft pivot axis AG axial opposite direction AR axial direction E Floor level G1 first gear stage G2 second gear stage RG radial opposite direction RR radial direction S swivel axis

Claims

[1] Gearbox (8) for a forklift truck (1), with a gearbox housing (13) that can be pivoted about a vertical pivot axis (S) on a vehicle frame (12) of the industrial truck (1), with an input shaft (15) for the drive-related connection of a drive machine (7), with an output shaft (16) for the drive-related connection of a vehicle wheel (6), with an intermediate shaft (19) arranged between the input shaft (15) and the output shaft (16), wherein the intermediate shaft (19) is connected to the input shaft (15) via a first gear stage (G1) and to the output shaft (16) via a second gear stage (G2), wherein the intermediate shaft (19) has an input-side output gear section (22) of the first gear stage (G1) and an output-side drive gear section (25) of the second gear stage (G2), wherein at least the input-side output gear section (22) is designed as a separate output gear which is positively and / or frictionally connected to the intermediate shaft (19), with an input-side and an output-side intermediate shaft bearing (35a, 35b) for rotatably supporting the intermediate shaft (19), wherein the two intermediate shaft bearings (35a, 35b) each have an inner ring (37), an outer ring (38) and several rolling elements (39) arranged to roll between the inner ring (37) and the outer ring (38), wherein the input-side output gear section (22) is arranged axially with respect to an intermediate shaft rotation axis (A3) between the two intermediate shaft bearings (35a, 35b), wherein the input-side intermediate shaft bearing (35a) is supported in a radial direction (RR) on the input-side output gear section (22) and in a radial opposite direction (RG) on the gearbox housing (13), and wherein the output-side intermediate shaft bearing (35b) is supported in the radial direction (RR) on the gearbox housing (13) and in the radial opposite direction (RG) is supported on the intermediate shaft (19), characterized by , that the input-side output gear section (22) and the output-side drive gear section (25) are supported against each other in the axial direction with respect to the intermediate shaft rotation axis (A3) via the inner ring (37) of the output-side intermediate shaft bearing (35b). [2] Gearbox (8) according to claim 1, characterized by , that the inner ring (37) of the input-side intermediate shaft bearing (35a) is non-rotatably connected to the gearbox housing (13) and the outer ring (38) of the input-side intermediate shaft bearing (35a) is non-rotatably connected to the input-side output gear section (22) and wherein the inner ring (37) of the output-side intermediate shaft bearing (35b) is non-rotatably connected to the intermediate shaft (19) and the outer ring (38) of the output-side intermediate shaft bearing (35b) is non-rotatably connected to the gearbox housing (13). [3] Gearbox (8) according to claim 1 or 2, characterized by that the two intermediate shaft bearings (35a, 35b) are each designed as an angular contact bearing. [4] Gearbox (8) according to claim 3, characterized by , that the pressure cones (43a, 43b) formed by the pressure lines of the two angular contact bearings are aligned with their tips in the axial direction with respect to the intermediate shaft rotation axis (A3). [5] Gearbox (8) according to any one of the preceding claims, characterized by , that an axial force acting on the intermediate shaft (19) in an axial direction (AR) can be supported by one intermediate shaft bearing (35a) in the gearbox housing (13) and an axial force acting on the intermediate shaft (19) in an axial opposite direction (AG) can be supported by the other intermediate shaft bearing (35b) in the gearbox housing (13). [6] Gearbox (8) according to any one of the preceding claims, characterized by , that the input-side output gear section (22) has a bearing receptacle (40) on its axial end face, wherein the input-side intermediate shaft bearing (35a) is received in the bearing receptacle (40). [7] Gearbox (8) according to claim 6, characterized by , that the outer ring (38) of the input-side intermediate shaft bearing (35a) is mounted in the bearing receptacle (40) in a rotationally fixed manner. [8] Gearbox (8) according to any one of the preceding claims, characterized by , that the input-side output gear section (22) is indirectly supported axially on the inner ring (37) of the output-side intermediate shaft bearing (35b) via a spacer element (42) or is directly supported via a cylindrical hub section of the input-side output gear section (22). [9] Gearbox (8) according to any one of the preceding claims, characterized by, that the gearbox housing (13) has a housing base body (29) and a housing cover (30), wherein the housing base body (29) has a first housing section (31) for receiving the first gearbox stage (G1) and a second housing section (32) for receiving the second gearbox stage (G2), wherein the first housing section (31) is covered in the axial direction with respect to the intermediate shaft rotation axis (A3) by the housing cover (30) and the input-side intermediate shaft bearing (35a) is supported in the radial opposite direction (RG) on the housing cover (30). [10] Gearbox (8) according to claim 9, characterized by , that the housing cover (30) has a support section (41) wherein the input-side intermediate shaft bearing is supported in the radial direction (RR) on the support section (41). [11] Gearbox (8) according to claim 10, characterized by, that the inner ring (37) of the input-side intermediate shaft bearing (35a) is mounted on the support section in a rotationally fixed manner. [12] Gearbox (8) according to any one of the preceding claims, characterized by , that the first gear stage (G1) is formed by a spur gear (20) or a traction gear, wherein the intermediate shaft (19) is aligned with the input shaft (15). [13] Gearbox (8) according to any one of the preceding claims, characterized by , that the second gear stage (G2) is formed by an angle gear (24), wherein the intermediate shaft (19) is aligned at an angle to the output shaft (16). [14] Gearbox (8) according to claim 13, characterized by , that the output-side drive wheel section (25) is designed as a bevel pinion (27) which meshes with a ring gear (28) which is non-rotatably connected to the output shaft (16). [15] Industrial truck (1) with the transmission (8) according to one of the preceding claims.

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