EP4127516A1

EP4127516A1 - Drive unit for a construction and/or material handling machine

Info

Publication number: EP4127516A1
Application number: EP21723159.6A
Authority: EP
Inventors: Klaus Graner; Martin Paal
Original assignee: Liebherr Components Biberach GmbH
Current assignee: Liebherr Electronics and Drives GmbH
Priority date: 2020-05-06
Filing date: 2021-04-28
Publication date: 2023-02-08
Also published as: DE102020116762A1; US20230151882A1; WO2021224075A1

Abstract

The invention relates to a drive unit for a construction and/or material handling machine or lifting equipment such as a crane, comprising a torque density of more than 20 Nm/I at a predetermined output speed, wherein the drive unit comprises a drive motor and a connected transmission, wherein a fast-running electric motor is provided as the drive motor, wherein the motor speed thereof is at least two times said output speed of the drive unit and is reduced by the transmission by a factor of at least 2 to the output speed of the drive unit.

Description

Drive unit for a construction and / or material handling machine

The present invention relates to a drive unit for a construction and / or material handling machine or a hoist such as a crane, with a torque density of more than 20 Nm / I at a predetermined output speed, the drive unit comprising a drive motor and a gear connected to it .

Drives for construction and / or material handling machines or hoists such as cranes have to provide high torques at relatively low speeds in order to slowly lift or move heavy loads or to be able to move the usually very heavy machines. For example, the hoist winches of cranes have to start very slowly when lifting heavy loads and at the same time provide high torques in order to be able to lift and move the load gently. Similar requirements are also placed on the drives of construction machinery such as mobile excavators, mobile cranes, crawler excavators, wheel loaders, bulldozers, concrete mixers or concrete pumps, or on material handling machines such as telescopic loaders or forklifts, with underground vehicles or machines generally used in the mining sector also having corresponding requirements Need drives. Also other mobile work machines such as municipal vehicles, for example in the form of sweepers, special tractors or waste collectors, as well as airport tractors, but also agricultural and forestry equipment, working platforms or drilling equipment require drives that have to meet similar requirements.

In order to be able to provide high torques at low speeds and at the same time to fit into the often cramped installation space of the installation environment, hydraulic drives have so far usually been used, for example in the form of axial piston motors that can be designed as constant or variable displacement motors. Such hydraulic motors fit into very tight installation spaces such as, for example, in the interior of the cable drum of a cable winch, and have a sufficiently high torque density at low output speeds. Such hydraulic motors for the machine types mentioned usually have torque densities in the range of 30 to 40 Nm / I and can provide torques in the range of 500 to 1,000 Nm or 100 to 2,000 Nm at low speeds, although the parameters mentioned depend on the hydrostatic configuration and size can deviate.

More recently, attempts have been made to replace such hydraulic drives with electric drives in order to achieve the advantages given by electrification. Electrification is known to be a trend that can make sense for a number of reasons. On the one hand, the goal is to save fuel due to better efficiency. On the other hand, the buzzword “Local Zero Emission” is also a topic for construction machinery or material handling machines and hoists in order to be able to work on site without an internal combustion engine that drives either a hydraulic pump or an electric generator. The electric drives can be fed from an energy storage device such as a battery or, in certain applications, such as in the mining sector, from the grid.

However, due to their low power density, electrical machines are not readily suitable for use in the machines mentioned, since the electrical machine usually does not meet the aforementioned boundary conditions can meet everyone equally. In order to be able to provide sufficiently high power or torque, the electric motor would have to be built correspondingly larger, which, however, is not possible if the space available in the installation environment is limited or if the electric motor is even installed as a replacement for a hydraulic drive in an otherwise unchanged machine environment shall be. On the other hand, the power density of the electric motor cannot easily be increased by increasing the speed, since the units to be driven such as cable winches, axles or gears usually cannot easily process increased speeds, at least not without structural adaptations. In particular, if a conventional hydraulic motor is to be replaced by an electric drive, the speeds of the drive unit can not simply be increased, since then the driven system could no longer work in the vorbe certain way.

The present invention is therefore based on the object of creating an improved drive unit of the type mentioned, which avoids the disadvantages of the prior art and further develops the latter in an advantageous manner. In particular, an exchange drive unit is to be created to replace a hydraulic drive, which can be installed without extensive redesign of the system units to be driven and which meets the torque and speed requirements of the system units to be driven.

According to the invention, the stated object is achieved by a drive unit according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

It is therefore proposed to provide an electric motor that runs too fast per se as the drive motor, whose motor speed, which is too high for the required output speed, is reduced by a connected gearbox to such an extent that the machine units to be driven, such as winches, axles or downstream gears, are provided for a hydraulic drive Design can be used further. According to the invention, a high-speed drive motor is the electric motor is provided, the engine speed of which is at least twice the predetermined output speed of the drive unit and is reduced by at least a factor of 2 to the output speed of the drive unit by the transmission integrated into the drive unit. The high-speed electric motor and the speed-reducing gear are advantageously combined to form a drive unit in the manner of a plug-and-play module, which, as a replacement for a hydraulic motor, can simply be connected to the machine units to be driven, without the machine components to be driven having to be reconfigured or themselves the person installing would have to think about this.

Due to the high torque density of at least more than 20 Nm / I, which is achieved by the inventive combination of an electric motor that runs significantly too fast with a significantly speed-reducing gear, the drive unit can also be installed in confined spaces in given installation environments and at the same time high torques at low Provide speeds as required by classic construction and / or material handling machines such as cranes.

In an advantageous development of the invention, the torque density of the drive unit consisting of high-speed electric motor and speed-reducing gear can be in the range of 20 to 40 Nm / I or 25 to 30 Nm / I.

The electric motor can advantageously run at a speed of more than 4,000 rpm or more than 8,000 rpm when the machine to be driven is in operation, with the motor speed also being 12,000 rpm or more. The engine speed can be more than three times or more than four times as high as the speed required by the unit to be driven.

In order to lower the very high engine speeds to a speed level that is typically achieved by hydrostats or hydraulic motors, the transmission can in an advantageous development of the invention have a transmission ratio of Have more than 3 or more than 4, i.e. reduce the engine speed by a factor of more than 3 or more than 4. In particular, the transmission ratio of the transmission integrated into the drive unit can be 4 to 5 slow.

Depending on the design of the machine component to be driven, another gear can be connected downstream, which is acted upon directly or indirectly, for example via a drive shaft, with the output speed of the gear unit integrated in the drive unit and thus the output speed of the drive unit. Even if the machine unit to be driven has its "own" transmission, the drive unit includes the aforementioned speed-reducing transmission in order to be able to connect the drive unit as a replacement module for a hydrostatic, for example, and to be able to provide the output speed for which the machine unit including the unit transmission is designed .

Advantageously, the gearbox integrated in the drive unit, which reduces the speed of the electric motor running too fast to the desired output speed range, can be accommodated together with the electric motor in a common housing of the drive unit, which houses the electric motor and the gearbox at least on the circumference and advantageously also on the front around closes so that essentially only the output shaft of the gearbox protrudes from the housing. Regardless of such a common housing, the electric motor and the transmission can be accommodated in separate, preferably sealed, in particular liquid-tight housing chambers.

As an alternative to a common housing, the electric motor and the gearbox connected to it can also have separate housing units that can preferably be connected to one another. Such separate motor and transmission housings make it possible to test the functionality of the electric motor and the transmission separately. In addition, any necessary repairs can be carried out more easily. Advantageously, the housing and / or housing sections of the electric motor and transmission can have at least approximately the same diameter and / or the same cross-sectional dimensions, so that the drive unit composed of the electric motor and transmission has an overall slim, preferably approximately smooth outer contour.

In order to enable the drive unit to be installed even in very cramped installation environments, such as the inside of the cable drum of a cable winch, it can be advantageous for the electric motor and the gear connected to it to be arranged coaxially to one another in a further development of the invention. In particular, the transmission output shaft can be arranged coaxially to the motor shaft.

With such a coaxial arrangement of electric motor and gear, said gear can advantageously be flanged to the front of the electric motor, with a gear housing in particular being able to connect to the front of the motor housing and / or be connected to it.

Advantageously, the design of the transmission and the electric motor connected to it can be such that the drive unit comprising the electric motor and the transmission has a length / diameter ratio of 2 to 4, i.e. approximately two to four times as long as thick or wide is.

Regardless of the specific geometric arrangement or dimensioning of the electric motor and transmission, it can be provided that the electric motor and the transmission have separate coolant circuits so that the electric motor and the transmission can be cooled by separate coolant flows. In an advantageous development of the invention, however, it can be provided that the electric motor and the transmission are cooled in parallel from the same coolant flow or connected in series from the same coolant flow. In the case of separate coolant circuits, however, a perfectly matching coolant circuit can be configured for the electric motor and the transmission and / or the corresponding coolant circuit can be controlled in accordance with the heat development in the electric motor or in the transmission. In particular, the electric motor and the transmission can be liquid-cooled, in particular oil-cooled or water-cooled.

Regardless of the coolant, the cooling circuit of the electric motor can have a coolant inlet on the transmission-side end section of the electric motor, while an outlet of the motor cooling circuit can be provided on an engine section facing away from the transmission. As a result, the part of the electric motor that is more thermally stressed by the transmission heat can be cooled more.

In order to achieve a sufficiently high speed reduction with a slim design, the transmission integrated into the drive unit can have at least one gear stage in a coaxial design, eg. B. comprise a planetary gear stage.

When such a planetary gear stage is provided, it can be advantageous if a planet carrier is arranged in an upright position, the upright planet carrier being permanently connected to a motor and / or gear housing and / or being able to form a part thereof. Independently of this, the stationary planet carrier can have a bearing section for the rotatable bearing of a transmission input shaft and / or the motor output shaft.

In principle, however, other gear designs are also possible.

The invention is explained in more detail below using a preferred exemplary embodiment and associated drawings. In the drawings show:

Fig. 1: a perspective view of a drive unit with a Schnelllau Fenden electric motor and a speed-reducing gear according to an advantageous embodiment of the invention,

FIG. 2: a side view of the drive unit from FIG. 1, the bearing of the output shaft being shown partially in section, and FIG Fig. 3: a longitudinal section through the drive unit from the preceding

Figures showing the front, coaxial connection of the gearbox to the electric motor.

As the figures show, the drive unit 1 comprises a drive motor 2, which is designed as a high-speed electric motor, and a speed-reducing gear 3 connected to it, which reduces the motor speed of the electric motor to the output speed of the drive unit 1.

The drive motor 2 and the gear 3 can advantageously be arranged coaxially to one another, wherein in particular the gear output shaft 4 can be arranged coaxially to the motor shaft 5, see FIG. 3.

The gear 3 can be accommodated in a - roughly speaking - cylindrical gear housing 6, which can have a collar-shaped mounting flange 7, by means of which the drive unit 1 can be mounted on the installation environment of a machine unit to be driven.

The drive motor 2 can comprise a motor housing that is separate from the gear housing 6, the gear housing 6 being able to be flanged on the front side of the motor housing 8. As an alternative to separate motor and gear housings, however, it would also be possible to accommodate the electric motor and the gear in a common housing and / or to form the aforementioned gear and motor housings 6 and 8 in one piece.

The motor housing 8 and the gear housing 6 can advantageously have at least approximately the same diameter, so that the drive unit 1 as a whole forms a slim, elongated, approximately cylindrical unit. As FIG. 1 and FIG. 3 show, the transmission output shaft 4 can protrude somewhat from the housing of the drive unit 1 on one end face of the drive unit 1 in the manner of a shaft stub. On the opposite end face of the drive unit 1, electrical connections for supplying and / or controlling the electric motor 2 can be provided, see FIG. 3.

The electric motor can be designed in different ways, with synchronous and asynchronous motors basically being considered. For example, the electric motor can be a synchronous motor with a permanent magnet.

The electric motor 2 is designed for a high speed range, it being possible to provide a speed range of 4,000 to 20,000 rpm or 5,000 to 15,000 rpm or 8,000 to 12,000 rpm, which is specific for working operation. The entire speed range can of course start at 0 and thus extend from 0 to 20,000 rpm or 0 to 15,000 rpm in order to be able to start from a standstill during operation.

The electric motor advantageously has a maximum speed that is at least 10,000 rpm. The motor can advantageously be operated at speeds in the range from 8,000 to 16,000 rpm or 10,000 to 14,000 rpm.

The gear 3 connected to the electric motor 2 advantageously has a transmission ratio of more than 2 or even more than 3, the transmission ratio being advantageously 4 to 5. The motor speed of the electric motor 2 is reduced by at least a factor of 2 or a factor of 3, in particular by a factor of 4 to 5, so that the output speed can be in the range from 1/2 to 1/5 of the motor speed. For example, if the electric motor runs at 14,000 rpm, the output speed of the drive unit is 1, i.e. the speed of the gear output shaft 4 is approx. 3,000, if the electric motor 2 can drive a speed range from zero to 14,000, the output speed of the drive unit is 1 zero to 3,000. In order to be able to achieve the aforementioned transmission ratio with a slim design, the transmission 3 can comprise at least one planetary gear stage 9. As FIG. 3 shows, such a planetary gear stage 9 can comprise an upright arranged planet carrier 10, which can be firmly connected to the motor housing 8 and / or the gear housing 6. Said planet carrier 10 can advantageously carry or support a rotary bearing 11 on which the motor shaft 5 and / or a transmission input shaft 12 is supported.

As FIG. 3 shows, the sun gear 13 can be connected to the transmission input shaft 12 in a rotationally fixed manner and can be in rolling engagement with the planets rotatably mounted on the planet carrier 10. A flea wheel 14, which is in rolling engagement with the planetary gears, can drive the transmission output shaft 4, in particular be connected to it in a rotationally fixed manner.

The drive unit 1 comprising the electric motor 2 and the transmission 3 can have a torque density of more than 20 Nm / I, for example a torque density of 20 to 40 or 25 to 30 Nm / I.

The drive unit 1 can provide a torque of, for example, more than 500 Nm or more than 1,000 Nm, for example in a range from 500 to 2,000 Nm or 1,000 to 1,500 Nm. Advantageously, however, the drive unit 1 can also start up very gently and also provide small torques starting at 0, which can then be raised to the level mentioned in the desired manner.

Claims

1. Drive unit for a construction and / or material handling machine or a hoist such as a crane, with a torque density of more than 20 Nm / I at a predetermined output speed, the drive unit (1) having a drive motor (2) and a gear unit connected to it ( 3), characterized in that the drive motor (2) is a fast-running electric motor, the motor speed of which is at least twice the stated output speed of the drive unit, and the gear unit (3) by a factor of at least 2 to the output speed of the drive unit (1) is reduced, is provided.

2. Drive unit according to the preceding claim, wherein the torque density of the drive unit is in the range of 20 to 40 Nm / I or 25 to 30 Nm / I and an engine speed in operation is more than 4,000 rpm or more than 8,000 rpm or is more than 12,000 rpm.

3. Drive unit according to one of the preceding claims, wherein the electric motor has a speed range of 0 to 5,000 rpm or 0 to 10,000 rpm or 0 to 15,000 rpm.

4. Drive unit according to one of the preceding claims, wherein the Ge gear (3) has a gear ratio of more than 3 or more than 4, in particular special 4 to 5, in the slow.

5. Drive unit according to one of the preceding claims, wherein the Ge gear (3) and the electric motor (2) are arranged coaxially to one another, in particular a motor shaft (5) is arranged coaxially to a transmission output shaft (4).

6. Drive unit according to the preceding claim, wherein the transmission (3) is flanged on the end face of the electric motor (2).

7. Drive unit according to one of the preceding claims, wherein a Mo gate housing (8) and a gear housing (6) have at least approximately the same diameter.

8. Drive unit according to the preceding claim, wherein the Motorge housing (8) is formed separately from the gear housing (6) and the ge-called motor and gear housing (8, 6) are rigidly, releasably connectable to each other.

9. Drive unit according to one of claims 1 to 7, wherein the gear (3) and the electric motor (2) are accommodated in a common housing and the motor and gear housing are integrally one-piece, homogeneously connected to one another.

10. Drive unit according to one of the preceding claims, wherein the drive unit (1) has a length / diameter ratio (L / d) in the range of 2 to 4.

11. Drive unit according to one of the preceding claims, wherein the drive motor (2) and the transmission (3) sit on a common coolant circuit be.

12. Drive unit according to the preceding claim, wherein the transmission (3) and the electric motor (2) are liquid-cooled.

13. Drive unit according to one of the two preceding claims, wherein the coolant circuit has an inlet on a transmission-side end portion of the electric motor (2) and a coolant outlet on an end portion of the electric motor facing away from the transmission.

14. Drive unit according to one of the preceding claims, wherein the Ge gear (3) comprises at least one coaxial gear stage (9).

15. Drive unit according to the preceding claim, wherein a stationary planet carrier (10) is provided, which is connected to a motor and / or gear housing (8, 6) and a pivot bearing for a gear input shaft (12) and / or the Motor shaft (5) carries.

16. Drive unit according to one of the preceding claims, wherein the drive unit (1) has a collar-shaped mounting flange (7) for attachment to a machine unit to be driven, said mounting flange (7) preferably being provided on an end section of the transmission housing.

17. Use of a drive unit (1), which is designed according to one of the preceding claims, for replacement with a hydraulic drive for driving a machine unit of a construction and / or material handling machine or a hoist.

18. Drive set comprising a drive unit (1) which is designed according to the preceding claims 1 to 16, and a hydraulic drive, where in the drive unit (1) and the hydraulic drive corresponding to each other Have connecting flanges and have torque densities that differ from one another by less than 50% or less than 30%.