DE102021209955A1 - Transmission for an industrial truck and industrial truck with the gearbox - Google Patents

Abstract

A transmission 8 for an industrial truck 1, with a transmission housing 13 that can be pivotably fastened to a vehicle frame 12 of the industrial truck 1, with an input shaft 15 for the drive connection of a drive motor 7, with an output shaft 16 for the drive connection of a vehicle wheel 6, with an intermediate input shaft 15 and output shaft 16, the intermediate shaft 19 being connected to the input shaft 15 via a first gear stage G1 and to the output shaft 15 via a second gear stage G2, the intermediate shaft 19 having an input-side output gear section 22 of the first gear stage G1 and an output-side Drive wheel section 25 of the second gear stage G2, proposed with an input-side and an output-side intermediate shaft bearing 35a, 35b for the rotatable mounting of the intermediate shaft 19, in which the input-side driven wheel section 22 in the axial Ri is arranged between the two intermediate shaft bearings 35a, 35b, the input-side intermediate shaft bearing 35a being supported in a radial direction RR on the input-side driven wheel section 22 and in a radial opposite direction RG on the transmission housing 13, and the output-side intermediate shaft bearing 35b being supported in the radial direction RR on the Transmission housing 13 and is supported on the intermediate shaft 19 in the opposite radial direction RG.

Description

The invention relates to a transmission for an industrial truck with the features of the preamble of claim 1. The invention also relates to an industrial truck with the transmission.

Industrial trucks are often driven with the help of steerable drives, which are rotatably connected to the industrial truck via a slewing ring bearing and can perform steering movements of 360 degrees and more on a steerable wheel of the vehicle. Two-stage gear drives are usually used to transfer the drive torque to the wheel, with a first stage usually being designed as a spur gear stage and a second stage as a bevel gear stage. These are characterized by a very compact design and a high torque density.

The pamphlet EP 1 285 803 A1 discloses a one-wheel drive, in particular for industrial trucks, consisting of a gear housing with at least one gear stage, a flanged-on drive motor and a driven impeller, the impeller being directly non-rotatably connected to a gear wheel and the gear wheel being rotatably mounted on a coaxially internal and fixed spacer element . The gearbox is designed in two stages, with a first gear stage having spur gear teeth being assigned to the drive motor, while a second gear stage having bevel gear teeth being assigned to the impeller. The two gear stages are connected by a drive shaft mounted in the housing.

The invention is based on the object of proposing a transmission of the type mentioned at the outset, which is characterized by a compact design and a robust construction.

This object is achieved by a transmission with the features of claim 1 and an industrial truck with the features of claim 15. Further configurations and advantages according to the invention emerge from the corresponding subclaims and the following description and attached figures.

The subject matter of the invention is a transmission which is designed and/or suitable for an industrial truck. In particular, the transmission has the function of converting a drive torque to a vehicle wheel of the industrial truck. For this purpose, an electric drive motor is connected to the vehicle wheel via the transmission. The drive machine is arranged on an input side or a drive side and the vehicle wheel on an output side or an output side of the transmission. Specifically, the transmission has a transmission ratio of i>1. In other words, the transmission serves to reduce speed, reducing a speed and increasing the transmitted torque.

The electric drive machine is designed to transmit an electrical drive torque to the vehicle wheel in a drive mode and an electrical braking torque in a generator mode. In the drive mode, the drive machine is used in particular as an electric motor, with the drive machine drawing electrical energy from an energy store and converting it into mechanical power in order to apply the drive torque to the vehicle wheel. In the generator mode, the drive machine is used in particular as a generator, with the drive machine converting mechanical energy into electrical energy by means of recuperation in order to apply the electrical braking torque to the vehicle wheel. In the generator mode, the electrical energy obtained is fed back into the energy store.

The transmission has a transmission housing that can be attached to a vehicle frame of the industrial truck so that it can pivot about a vertical pivot axis. In particular, the transmission housing is mounted on the vehicle frame such that it can be pivoted about the pivot axis via a slewing ring bearing. In particular, the vehicle wheel is designed as a steerable vehicle wheel that can be driven or braked by the drive unit depending on the driving situation and can be pivoted about the pivot axis by the transmission housing to implement a steering movement. The vehicle wheel preferably has a steering angle of more than 180 degrees, preferably more than 360 degrees. In particular, “vertical” in relation to the pivot axis is to be understood in such a way that the pivot axis is aligned vertically, preferably essentially perpendicularly, to a floor level when the transmission is installed. The vehicle wheel preferably defines a wheel axis of rotation about which the vehicle wheel rotates when driving. The axis of rotation of the wheel is particularly preferably horizontal, preferably in the same direction, aligned with the floor level. The prime mover is arranged coaxially to the pivot axis. In particular, the drive machine has a stator and a rotor rotating about a machine axis of rotation, the pivot axis being defined by the machine axis of rotation and/or the pivot axis and the machine axis of rotation being arranged on the same axis as one another. The stator is preferably non-rotatable and/or stationary in relation to a vehicle frame of the vehicle. This allows the supply and Signal lines for the electrical machine are laid permanently.

On the input side, the transmission has an input shaft, which is designed and/or suitable for the drive-related connection of the drive machine. In particular, the input shaft is connected in a torque-transmitting, preferably non-rotatable manner to a drive shaft, preferably a rotor shaft driven by the rotor, of the prime mover. Alternatively, however, it can also be provided that the input shaft is formed by the drive shaft of the drive machine. The input shaft is preferably arranged coaxially to the pivot axis or the axis of rotation of the machine.

The transmission has an output shaft on the output side, which is designed and/or suitable for the drive connection of the vehicle wheel. In particular, the output shaft is connected in a torque-transmitting, preferably non-rotatable manner to an output shaft, preferably a wheel hub driving the vehicle wheel. Alternatively, however, it can also be provided that the output shaft is formed by the driven shaft, in particular the wheel hub. The output shaft is preferably arranged coaxially with the axis of rotation of the wheel.

The transmission has an intermediate shaft arranged between the input shaft and the output shaft. In particular, the intermediate shaft is arranged in the same direction as the input shaft and/or at an angle to the output shaft. The intermediate shaft is connected in terms of transmission technology to the input shaft via a first gear stage, in particular on the input side, and is connected in terms of gear technology to the output shaft via a second gear stage, in particular on the output side. The first gear stage serves in particular to form a center distance between the input shaft and the intermediate shaft. This center distance is necessary in order to be able to place the intermediate shaft next to the vehicle wheel. The second gear stage serves in particular to deflect the drive torque from the intermediate shaft to the output shaft. The transmission can have exactly the first and the second gear stage. Alternatively, however, the transmission can also have more than two transmission stages.

The intermediate shaft has an input-side driven wheel section of the first gear stage and an output-side drive wheel section of the second gear stage. In particular, the output gear section on the input side is operatively connected to an input-side drive wheel section of the input shaft in a torque-transmitting manner. In particular, the output-side drive wheel section is operatively connected to an output-side driven wheel section of the output shaft in a torque-transmitting manner. In principle, the driven wheel section on the input side and/or the drive wheel section on the output side of the intermediate shaft can be designed as a separate component which is connected to the intermediate shaft in a torque-proof manner. For example, the input-side driven wheel section and/or the output-side drive wheel section can be connected in a torque-proof manner to the intermediate shaft via a form fit, e.g. splines, and/or a force fit, e.g. press fit. Alternatively, the input-side driven wheel section and/or the output-side drive wheel section and the intermediate shaft can be manufactured in one piece, in particular from a common material section.

The transmission has an input-side and an output-side intermediate shaft bearing, which are designed and/or suitable for the rotatable mounting of the intermediate shaft in the transmission housing. In particular, the input-side intermediate shaft bearing is arranged on the input side of the transmission, preferably close to the input-side output gear section. In particular, the output-side intermediate shaft bearing is arranged on the output side of the transmission, preferably close to the output-side drive wheel section.

In the context of the invention, it is proposed that the output gear section on the input side is arranged in the axial direction between the two intermediate shaft bearings. In other words, the input-side driven wheel section is arranged inside the intermediate shaft bearing and the output-side drive wheel section is arranged outside of the intermediate shaft bearing. The input-side intermediate shaft bearing is supported on the input-side driven gear portion in a radial direction and on the transmission case in an opposite radial direction. The output-side intermediate shaft bearing is supported on the transmission case in the radial direction and on the intermediate shaft in the opposite radial direction. In particular, the radial direction and the radial counter-direction are to be understood in relation to an intermediate shaft axis of rotation about which the intermediate shaft rotates during operation.

The invention is based on the finding that the installation space available for mounting the intermediate shaft is limited and, depending on the design of the transmission, is specified by the permissible radius of the enveloping circle of the drive and/or by the required load capacity of the wheelset of the second gear stage. In addition, the required lifetimes are very long. In particular, the toothing and the intermediate shaft bearing on the output side of the intermediate shaft are the most vital life-limiting components. The connection between the intermediate shaft and the output gear section on the input side is also heavily loaded. Furthermore, the invention is based on the finding that the intermediate shaft bearing on the output side is arranged next to the vehicle wheel and cannot be made arbitrarily large with regard to the outer diameter. The inside diameter of this bearing is also limited, since the gearing of the intermediate shaft limits its diameter in the area of the bearing.

The arrangement of the intermediate shaft bearings according to the invention proposes a bearing arrangement for the intermediate shaft that can be designed in such a way that it reliably meets the service life requirements and also provides sufficient installation space for the drive wheel section on the output side in order to be able to achieve the required service life of the gearing. In particular, the bearing distance 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 transmission is thus proposed which is characterized by a compact design and a robust structure.

In a specific embodiment, it is provided that the intermediate shaft bearing on the input side and the intermediate shaft bearing on the output side are each designed as a roller bearing. In particular, the two intermediate shaft bearings serve to absorb radial and/or axial forces in relation to the intermediate shaft axis of rotation. The intermediate shaft bearings each have an inner ring and an outer ring as well as a plurality of rolling bodies arranged to roll between the inner ring and the outer ring. In principle, the inner and/or outer rings can be designed as separate bearing rings, which are preferably non-positively 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 non-rotatably connected to the transmission housing and the outer ring of the input-side intermediate shaft bearing is non-rotatably connected to the input-side output gear section. The inner ring of the output-side intermediate shaft bearing, however, is non-rotatably connected to the intermediate shaft and the outer ring of the output-side intermediate shaft bearing is non-rotatably connected to the transmission housing. In one operation, the inner ring of the output-side intermediate shaft bearing rotates and the outer ring is fixed, while the outer ring of the input-side intermediate shaft bearing rotates and the inner ring is fixed. By supporting the input-side intermediate shaft bearing on the input-side output gear section, a particularly compact bearing arrangement is proposed, which offers an enlarged bearing base even with short intermediate shafts.

In a further specification, it is provided that the intermediate shaft bearing on the input side and the intermediate shaft bearing on the output side are each designed as an angular bearing. In particular, an angular contact bearing is to be understood as meaning a roller bearing which is used to absorb axial and radial forces in relation to the intermediate shaft axis of rotation. The two intermediate shaft bearings are preferably each designed as tapered roller bearings. Alternatively, however, the two intermediate shaft bearings can also be designed as angular contact ball bearings or deep groove ball bearings.

In a further development it is provided that the pressure cones formed by the pressure lines of the two angular bearings are aligned with their pressure cone tips in the axial direction in relation to the intermediate shaft axis of rotation. The pressure lines are to be understood as lines of force flow along which a load is transferred from one bearing ring to the other bearing ring via the rolling elements. In particular, the pressure lines of an angular contact bearing each define a pressure cone which determines the arrangement of the bearing sets, the pressure lines intersecting at the pressure cone tips. In particular, the pressure lines of the two angular bearings are aligned. A bearing arrangement is thus proposed which, on the one hand, serves to absorb axial forces and, on the other hand, enables simple assembly of the intermediate shaft.

In a further specific embodiment, it is provided that an axial force acting on the intermediate shaft in an axial direction can be supported in the transmission housing by one, in particular the input-side intermediate shaft bearing, and an axial force acting on the intermediate shaft in an opposite axial direction by the other, in particular the output-side Intermediate shaft bearing can be supported in the transmission housing. In particular, the axial force acting on the input-side intermediate shaft bearing is transmitted from its outer ring to its inner ring. In particular, the axial force acting on the output-side intermediate shaft bearing is transmitted from its inner ring to its outer ring. A bearing arrangement is thus proposed which, in addition to radial forces, can also absorb axial forces in the positive and negative direction in relation to the intermediate shaft axis of rotation.

In a further specific embodiment, it is provided that the input-side output gear section has a bearing on its axial end face has acceptance, in which the input-side intermediate shaft bearing is included. In particular, the bearing mount is designed as a cylindrical mount, preferably a depression or opening. The intermediate shaft bearing on the input side can be accommodated in the bearing mount in a form-fitting and/or force-fitting manner, at least in the radial direction. In particular, the intermediate shaft bearing on the input side is accommodated partially or completely countersunk in the bearing mount in the axial direction. A transmission is thus proposed which is characterized by a particularly compact design.

In a further specification, it is provided that the outer ring of the intermediate shaft bearing on the input side is mounted in a rotationally fixed manner in the bearing mount. In particular, the outer ring of the intermediate shaft bearing on the input side is non-positively mounted, in particular by means of a press fit, in the bearing mount. In particular, the outer ring of the intermediate shaft bearing on the input side can be preassembled in the bearing mount. Alternatively, however, the outer ring of the intermediate shaft bearing on the input side can also be integrated into the input-side output gear section by means of a running surface arranged in the bearing mount. A transmission is thus proposed which is characterized by particularly simple assembly.

In a further specific implementation, it is provided that the input-side driven wheel section and the output-side drive wheel section are supported on one another in the axial direction in relation to the intermediate shaft axis of rotation via the output-side intermediate shaft bearing, in particular its inner ring. In particular, at least the input-side driven wheel section is designed as a separate driven wheel, which is connected to the intermediate shaft in a positive and/or non-positive manner. In particular, the output gear is connected in the direction of rotation to the intermediate shaft in a rotationally fixed manner via a form-fitting contour, preferably a spline. The output wheel is optionally secured in the axial direction by a securing means, preferably at least one locking nut or locking screw. Alternatively, the output gear can be connected to the intermediate shaft via a press fit. The output driven wheel on the input side is preferably supported indirectly axially via a spacer element, preferably a cylinder liner, on the output-side intermediate shaft bearing, in particular its inner ring. Alternatively, however, the input-side driven wheel can also have a cylindrical hub section, via which the driven wheel is supported directly on the output-side intermediate shaft bearing, in particular its inner ring.

In a further embodiment it is provided that the transmission housing has a housing base body and a housing cover. In particular, the transmission housing is designed in two parts. The housing cover is preferably mounted on the vehicle frame via the slewing ring bearing so that it can pivot about the pivot axis, with the housing base body being firmly connected to the housing cover, preferably screwed. The basic housing body has a first housing section for accommodating the first gear stage and a second housing section for accommodating the second gear stage. In particular, the first housing section is open in the axial direction with respect to the engine axis of rotation, in particular in the direction of the drive engine, and the second housing section is open in the axial direction with respect to the engine axis of rotation, in particular in the direction of the vehicle wheel. The first housing section is covered by the housing cover in the axial direction in relation to the intermediate shaft axis of rotation, the input-side intermediate shaft bearing being supported on the housing cover in the opposite axial direction. In particular, the housing cover is designed in such a way that the input-side output gear section is rotatably mounted in or on the housing cover in the radial and in the axial direction via the input-side intermediate shaft bearing.

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 intermediate shaft bearing on the input side. In particular, the input-side intermediate shaft bearing is supported on the support section in a positive and/or non-positive manner at least in the opposite radial direction. In particular, the support section is designed as a cylinder section arranged coaxially and/or concentrically to the intermediate shaft. The intermediate shaft is partially accommodated radially inside the cylinder section, the intermediate shaft rotating relative to the cylinder section during operation. In particular, the intermediate shaft is spaced apart from the cylinder section in the radial direction by an annular gap. The input-side intermediate shaft bearing is preferably radially supported on an outer circumference of the cylinder section. A transmission housing is therefore proposed which is characterized by a compact design.

Alternatively, the support section can be designed as a cylinder bore arranged coaxially and/or concentrically to the intermediate shaft. The cylinder bore preferably serves to accommodate a bearing cap, with the inner ring of the intermediate shaft bearing on the input side being accommodated in the bearing cap. In this case, the Bearing cover to allow adjustment of the bearing preload for the two intermediate shaft bearings without having to dismantle the housing cover from the housing body.

In a further specific implementation, it is provided that the inner ring of the input-side intermediate shaft bearing is mounted in a rotationally fixed manner on the support section. In particular, the inner ring of the input-side intermediate shaft bearing is non-positively mounted on the support section, in particular via a press fit. The inner ring of the intermediate shaft bearing on the input side can preferably be preassembled on the support section. Alternatively, however, the inner ring can also be integrated into the housing cover by a running surface arranged on the support section. A transmission is thus proposed which is characterized by particularly simple assembly.

In a further development it is provided that the first gear stage is formed by a spur gear. In particular, the spur gear can optionally be designed as a non-positive or positive spur gear. Designed as a non-positive spur gear, the first gear stage is preferably designed as a friction gear, also known as a rolling element gear. In particular, the input-side drive and driven gear sections are each designed as a friction wheel for this purpose, which are in frictional contact with one another. Designed as a form-fitting spur gear, the first gear stage is preferably designed as a toothed gear. In particular, the input-side drive and driven gear sections are each designed as a gear wheel for this purpose, which are in meshing engagement with one another. Alternatively, the first gear stage is formed by a traction mechanism. The traction mechanism can optionally be designed as a non-positive or positive traction mechanism. Designed as a non-positive traction drive, the first gear stage is preferably designed as a belt drive. In particular, the input-side drive and driven wheel section are each designed as a belt pulley for this purpose, which are frictionally connected to one another in a torque-transmitting manner via a traction mechanism. Designed as a form-fitting traction drive, the first gear stage is preferably designed as a chain drive. In particular, the input-side drive and driven gear sections are each designed as a toothed disk for this purpose, which are connected to one another in a form-fitting manner via a traction mechanism in a torque-transmitting manner.

In a further development it is provided that the second gear stage is formed by an angular gear. The bevel gear is preferably 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 in that the axes of rotation of the intermediate shaft and the output shaft have a common point of intersection. A particularly cost-effective bevel gear is thus proposed. Alternatively, the bevel gear is a hypoid gear. In particular, a hypoid gear is characterized in that the axes of rotation of the intermediate shaft and the output shaft are offset from one another or do not have a common point of intersection. For example, the running smoothness and the resilience of the bevel gear can be improved by a positive axis offset. A particularly robust bevel gear is thus proposed.

In a specific structural embodiment, it is provided that the drive wheel section on the output side is designed 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 spline. The bevel pinion and the intermediate shaft are preferably made in one piece, in particular from a common material section. In an embodiment as a bevel gear, the bevel pinion and the ring gear each have straight, helical or curved teeth. In the case of an embodiment as a hypoid gear, the bevel pinion and the ring gear each have curved teeth.

Another subject of the invention relates to an industrial truck with the transmission as already described above or according to one of claims 1 to 14. The industrial truck preferably has at least or exactly two wheel axles and at least or exactly three vehicle wheels. In particular, the industrial truck has a drive unit with the drive motor, the transmission and with exactly one driven, steerable vehicle wheel. In particular, the vehicle has a front axle with two front wheels and a rear wheel, the rear wheel forming the driven, steerable vehicle wheel. Alternatively, the vehicle can have a rear axle with two vehicle wheels and a front wheel, with the front wheel forming the driven, steerable vehicle wheel.

• 1 eine schematische Darstellung eines Fahrzeugs mit einer Antriebseinheit als ein Ausführungsbeispiel der Erfindung;
• 2 eine Schnittdarstellung der Antriebseinheit für das Fahrzeug gemäß 1;
• 3 eine Detailansicht der Schnittdarstellung der 2.

The present invention is explained in more detail below with reference to a drawing. It shows:

• 1 a schematic representation of a vehicle with a drive unit as an embodiment of the invention;
• 2 a sectional view of the drive unit for the vehicle according to FIG 1 ;
• 3 a detailed view of the sectional view of the 2 .

1 shows a vehicle 1 with a drive unit 2, which is set up to drive the vehicle 1, in a highly schematic representation. The vehicle 1 is a three-lane industrial truck, for example 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 vehicle wheel 6 of the vehicle 1.

The drive unit 2 has an electric drive machine 7 which is drive-connected to the driven, steerable vehicle wheel 6 via a two-stage gear 8 . For example, the electric drive machine 7 is a three-phase asynchronous motor, but alternatively other electric machines, such as synchronous motors, can also be used.

The vehicle 1 has an electrical energy store 9 which is used to provide and store electrical energy for the drive machine 7 . The electrical energy store 9 is a battery or an accumulator, for example. An inverter, not shown, is used to control the drive machine 7 and regulates the operating state of the drive machine 7 for the respective driving situation.

In order to move or accelerate the vehicle 1 in a forward or reverse direction V, R, the drive machine 7 operates in a drive mode, with the drive machine 7 converting the electrical energy provided by the energy store 9 into mechanical energy. In order to decelerate the vehicle 1 in the forward or reverse direction V, R, the drive machine 7 operates in generator mode, with the drive machine 7 converting mechanical energy into electrical energy and making it available to the energy store 9 .

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, the rotor 11 rotating 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 in 1 shown connected. In an installed state, the drive machine 7 is arranged vertically, with the machine axis of rotation A1 being arranged essentially perpendicular to a floor level E. Floor level E is defined by a subsurface on which vehicle wheel 6 (not shown here) stands or rolls during operation. During operation, the vehicle wheel 6 is rotated about a horizontal wheel axis of rotation A2, which is aligned parallel and/or in the same direction as the floor level 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 one another.

The gear 8 is designed as a two-stage gear and has a first gear stage G1 and a second gear stage G2. The two gear stages G1, G2 are installed in a gear housing 13, which is rotatably connected to the vehicle frame 12 via a slewing ring bearing 14. The transmission housing 13 can be pivoted 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. As a result, the drive unit 2 can be steered. For example, the gear housing 13 is connected to a steering drive, not shown, which transmits a pivoting movement about the pivot axis S to the gear housing 13 . In this case, the steering angle can be arbitrary, ie it can also be 360° or greater.

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 drivingly connected to a drive shaft 17 of the drive machine 7, which is driven in operation by the rotor 11 about the machine axis of rotation A1. For example, the input shaft 15 and the drive shaft 17 are made in one piece, e.g. The output shaft 16 is drivingly connected to an output shaft 18 designed as a wheel hub, which drives the vehicle wheel 6 about the wheel axis of rotation A2 during operation. For example, the output shaft 16 and the driven shaft 18 or the wheel hub are made in one piece, e.g. made of one piece.

The transmission 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 transmission housing 13 about an intermediate shaft axis of rotation A3, with one intermediate shaft axis of rotation A3 being aligned axially parallel to the machine axis of rotation A1 and at an angle, in particular at right angles, to the wheel axis of rotation A2. The intermediate shaft 19 is geared to the input shaft 15 via the first gear stage G1 and via the second gear stage G2 connected to the output shaft 16 in terms of transmission technology. The first gear stage G1 thus forms an input-side gear stage and the second gear stage G2 forms an output-side gear stage. A torque path runs from the engine 7 via the first gear stage G1 to the intermediate shaft 19 and via the second gear stage G2 to the vehicle wheel 6.

The first gear stage G1 is formed by a spur gear 20, with the spur gear 20 having an input-side drive gear section 21 connected non-rotatably to the input shaft 15 and an input-side output gear section 22 connected non-rotatably to the intermediate shaft 19, which mesh with one another. In particular, the input-side drive wheel and driven wheel section 22, 23 are each formed as a spur gear 23.

The second gear stage G2 is formed by a bevel gear 24, with the bevel gear 24 having an output-side drive wheel section 25 connected non-rotatably to the intermediate shaft 19 and an output-side driven wheel section 26 connected non-rotatably to the output shaft 16, which mesh with one another. The drive wheel section 25 on the output side is designed as a bevel pinion 27 and the driven wheel section 26 on the output side is designed as a ring gear 28 . The bevel gear 24 serves to deflect the torque path from the intermediate shaft 19 to the output shaft 16 . For this purpose, the bevel gear 24 can be designed either as a bevel gear or as a hypoid gear.

The transmission housing 13 has 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 firmly screwed to the housing base 29 . The housing base body 29 has a first housing section 31 for accommodating the first gear stage G1 and a second housing section 32 for accommodating the second gear stage G2. The input shaft 15 and the drive shaft 17 of the engine 7 are designed in one piece and supported by means of 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.

The intermediate shaft 19 is guided from the first housing section 31 into the second housing section 32, the intermediate shaft 19 being rotatably mounted in the first housing section 31 via an input-side intermediate shaft bearing 35a and also in the first housing section 31 via 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 roller bearings.

3 shows a detailed view of the drive unit 2, 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 wheel section 25 designed as a bevel pinion 27 and the intermediate shaft 19 being made from a common material section. The input-side driven gear section 22 designed as a spur gear 23 is designed as a helical gear which is arranged opposite to the bevel pinion 27 in the axial direction with respect to the intermediate shaft axis of rotation A3. The spur gear 23 is rotatably mounted on the intermediate shaft 19 via a spline, for example, and secured in an axial direction AR via two securing means 36 . The two securing means 36 are each designed as a screw nut, with the intermediate shaft 19 having a corresponding external thread at the end for this purpose.

A tapered roller bearing in an O arrangement is usually used to support the intermediate shaft 19, with both the spur gear teeth (input side driven wheel section 22) and the bevel gear teeth (output side drive wheel section 25) being arranged in the axial direction outside of the two bearing points (intermediate shaft bearings 35a, 35b). The distance between the two bearing points 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 solution described is the need for an 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 implemented by a nut (securing means 36). The toothed shaft profile is usually equipped with a small amount of play, which can lead to small movements of the spur gear on the intermediate shaft. The slight play is necessary for the assembly process, although these movements can also cause a loosening moment for the nut (securing means 36). To prevent the nut from loosening, additional measures are required to secure the nut. Since the overall height of the drive cannot be increased either, the possible safety measures are limited to measures that require a low overall height. For example, the nut is secured by a thread adhesive. Should the mother loosen, this can lead to Total failure of the gearbox due to tooth breakage of the bevel gear teeth.

In an alternative implementation, it is known to arrange the bearings (intermediate shaft bearings 35a, 35b) within the bevel gearing (output-side drive gear section 25) and the spur gearing (input-side driven gear section 22) in an X-arrangement. However, the inner diameter and the width of the bearing, which is arranged on the bevel gear teeth of the bevel gear shaft, are relatively small because they are limited by the geometry of the teeth of the bevel gear stage (second gear stage G2) and the bearing is on the small side of the truncated cone (bevel pinion 27 ) of the bevel gear shaft (intermediate shaft 19). The outside 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 gearbox.

It will therefore be in accordance with 3 a bearing for the intermediate shaft 19 has been proposed, in which the bevel pinion 27 is located below the two intermediate shaft bearings 35a, 35b and the spur gear 23 is fastened to the intermediate shaft 19 between the two intermediate shaft bearings 35a, 35b. The input-side intermediate shaft bearing 35a is supported on the input-side driven wheel section 22 in a radial direction RR and on the housing cover 30 in an opposite radial direction RG. The output-side intermediate shaft bearing 35b is supported on the housing base body 29 in the radial direction RR and on the intermediate shaft 19 in the opposite radial direction RG.

The two intermediate shaft bearings 35a, 35b are each designed as tapered roller bearings, the two intermediate shaft bearings 35a, 35b each having an inner ring 37, an outer ring 38 and a plurality of 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. If the intermediate shaft 19 rotates about the intermediate shaft axis of rotation A3, the inner ring 37 of the intermediate shaft bearing 35b on the output side also rotates together with it. The outer ring 38 of the output-side intermediate shaft bearing 35b is accommodated in the housing main body 29 and does not rotate.

The spur gear 23 has a bearing mount 40 on the axial end face for accommodating the input-side intermediate shaft bearing 35a. In addition, the housing cover 30 has a support section 41 arranged coaxially with the bearing receptacle 40 for supporting the intermediate shaft bearing 35a on the input side. The bearing seat 40 is designed as a cylindrical depression and the support section 41 as a cylindrical projection, the cylindrical projection extending in sections into the depression. The outer ring 38 of the input-side intermediate shaft bearing 35a is accommodated in the bearing mount 40 . When the intermediate shaft 19 rotates around the intermediate shaft rotational 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 received on an outer periphery of the support section 41 and does not rotate. The intermediate shaft 19 is arranged in sections with the two securing means 36 radially inside the support section 41 .

Furthermore, a spacer element 42, e.g. a cylinder bushing, is arranged between the spur gear 23 and the output-side intermediate shaft bearing 35b, with the spur gear 23 being supported in an opposite axial direction AG in relation to the intermediate shaft axis of rotation 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 intermediate shaft bearing 35b on the output side.

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

The contact pattern of the second gear stage 21 can be adjusted by inserting one or more shims (not shown) on the face side between the housing base body 29 and the outer ring 38 of the output-side intermediate shaft bearing 35b. The position of the intermediate shaft 19 in relation to the ring gear 28 can thus be adjusted. The preload of the two intermediate shaft bearings 35a, 35b can be adjusted by inserting one or more shims (not shown) on the face side between the housing cover 30 and the inner ring 37 of the input side intermediate shaft bearing 35a.

With the proposed bearing arrangement, the effective bearing base (distance between the pressure cone tips of the tapered roller bearings) can be increased compared to the known arrangements, since the input-side intermediate shaft bearing 35a is located above the spur gear 23. A bearing for the intermediate shaft 19 is thus proposed which, on the one hand, reliably meets the service life requirements and, on the other hand, provides sufficient installation space for the bevel gear teeth. In addition, the intermediate shaft bearing 35b on the output side is located above the bevel gear toothing of the bevel pinion 27. As a result, 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. In addition, 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 securing means 36 and the outer ring 38 of the input-side intermediate shaft bearing 35a can be preassembled outside of the transmission 8, which considerably simplifies the assembly of the transmission 8. A further advantage is that the bearing arrangement described can also be implemented with a short intermediate shaft 19 in which there is not enough installation space to arrange both intermediate shaft bearings 35a, 35b between the bevel gear 27 and the spur gear 23.

Reference List

1

vehicle

2

drive unit

3

front axle

4

first front wheel

5

second front wheel

6

vehicle wheel

7

prime mover

8th

transmission

9

energy storage

10

stator

11

rotor

12

vehicle frame

13

gear case

14

slewing ring bearing

15

input shaft

16

output shaft

17

drive shaft

18

output shaft

19

intermediate shaft

20

spur gear

21

input side impeller section

22

input driven gear section

23

spur gear

24

bevel gear

25

output side impeller section

26

output side driven gear section

27

bevel pinion

28

ring gear

29

housing body

30

housing cover

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

intermediate shaft bearing on the input side

35b

intermediate shaft bearing on the output side

36

collateral

37

inner ring

38

outer ring

39

rolling elements

40

stock pick-up

41

support section

42

spacer element

43a

inlet-side pressure cone

43b

outlet-side pressure cone

A

center distance

A1

machine axis of rotation

A2

wheel axis

A3

Intermediate shaft axis of rotation

Inc

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

pivot axis

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1285803 A1 [0003]

Claims (15)

Transmission (8) for an industrial truck (1), with a transmission housing (13) that can be attached to a vehicle frame (12) of the industrial truck (1) such that it can be pivoted about a vertical pivot axis (S), with an input shaft (15) for the drive connection of a drive machine ( 7), with an output shaft (16) for drivingly connecting a vehicle wheel (6), with an intermediate shaft (19) arranged between the input shaft (15) and the output shaft (16), the intermediate shaft (19) having a first gear stage (G1). the input shaft (15) is connected in terms of transmission technology and is connected in terms of transmission technology to the output shaft (15) via a second gear stage (G2), the intermediate shaft (19) having 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), with an input-side and an output-side intermediate shaft bearing (35a, 35b) for the rotatable L Bearing of the intermediate shaft (19), characterized in that the input-side output gear section (22) is arranged in the axial direction in relation to an intermediate shaft axis of rotation (A3) between the two intermediate shaft bearings (35a, 35b), the input-side intermediate shaft bearing (35a) being in a radial direction (RR) on the input-side output gear section (22) and in a radial opposite direction (RG) on the transmission housing (13) and wherein the output-side intermediate shaft bearing (35b) is supported in the radial direction (RR) on the transmission housing (13) and in the opposite radial direction (RG) is supported on the intermediate shaft (19). Gear (8) after claim 1 , characterized in that the two intermediate shaft bearings (35a, 35b) each have an inner ring (37), an outer ring (38) and several rolling bodies (39) arranged to roll between the inner ring (37) and the outer ring (38), the inner ring (37 ) of the input-side intermediate shaft bearing (35a) is non-rotatably connected to the gear 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 the inner ring (37) of the output-side intermediate shaft bearing (35b) is non-rotatably connected with the intermediate shaft (19) and the outer ring (38) of the output-side intermediate shaft bearing (35b) is non-rotatably connected to the transmission housing (13). Gear (8) after claim 1 or 2 , characterized in that the two intermediate shaft bearings (35a, 35b) are each designed as an angular bearing. Gear (8) after claim 3 , characterized in that the pressure cones (43a, 43b) formed by the pressure lines of the two angular bearings are rectified with their tips in the axial direction in relation to the intermediate shaft axis of rotation (A3). Transmission (8) according to one of the preceding claims, characterized in 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 transmission housing (13) and one on the intermediate shaft (19) axial force acting in an opposite axial direction (AG) can be supported in the transmission housing (13) by the other intermediate shaft bearing (35b). Transmission (8) according to one of the preceding claims, characterized in that the input-side output gear section (22) has a bearing mount (40) on its axial end face, the input-side intermediate shaft bearing (35a) being accommodated in the bearing mount (40). Gear (8) after claim 6 , characterized in that the outer ring (38) of the input-side intermediate shaft bearing (35a) is non-rotatably mounted in the bearing mount (40). Transmission (8) according to one of the preceding claims, characterized in that the input-side driven wheel section (22) and the output-side drive wheel section (25) are supported on one another in the axial direction in relation to the intermediate shaft axis of rotation (A3) via the output-side intermediate shaft bearing (35b). Transmission (8) according to one of the preceding claims, characterized in that the transmission housing (13) has a housing base body (29) and a housing cover (30), the housing base body (29) having a first housing section (31) for accommodating the first gear stage ( G1) and a second housing section (32) for accommodating the second gear stage (G2), the first housing section (31) being covered by the housing cover (30) in the axial direction in relation to the intermediate shaft axis of rotation (A3) and the input-side intermediate shaft bearing ( 35a) is supported on the housing cover (30) in the opposite radial direction (RG). Gear (8) after claim 9 , characterized in that the housing cover (30) has a support portion (41), wherein the one the output-side intermediate shaft bearing is supported in the radial direction (RR) on the support portion (41). Gear (8) after claim 10 , characterized in that the inner ring (37) of the input-side intermediate shaft bearing (35a) is non-rotatably mounted on the support section. Transmission (8) according to one of the preceding claims, characterized in that the first transmission stage (G1) is formed by a spur gear (20) or a traction mechanism, the intermediate shaft (19) being rectified to the input shaft (15). Gear (8) according to one of the preceding claims, characterized in that the second gear stage (G2) is formed by an angular gear (24), the intermediate shaft (19) being aligned at an angle to the output shaft (16). Gear (8) after Claim 13 , characterized in that the output-side drive wheel section (25) is designed as a bevel pinion (27) which meshes with a ring gear (28) connected non-rotatably to the output shaft (15). Industrial truck (1) with the transmission (8) according to one of the preceding claims.

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