Planetary gear transmission systems or components – Planetary gearing or element
Patent
1996-07-10
1998-07-14
Ta, Khoi Q.
Planetary gear transmission systems or components
Planetary gearing or element
475348, 74443, F16H 146
Patent
active
057795886
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a lifting equipment drive including a motor which drives, via a two-stage planetary transmission, a rotary hub mounted on a fixed hub carrier. The planetary transmission's first planetary gear set has a driven sungear and a planetary gear carrier, which is rotary connected with a sun gear of the second planetary gear set and whose planetary gears are intermeshed with ring gears which rotate at the same speed.
In the field of lifting equipment, elevators are driven at relatively low speeds. Therefore, corresponding low speeds are necessary on the elevator drive's output shaft. Generally, reversed polarity electric motors are used which operate with an open loop control. The elevator is driven up to a short distance from the stop position before being dynamically slowed down until the stop position (exit point) is reached.
A lifting equipment drive constitutes a compact drive unit which can be both installed and maintained in the most restricted spaces.
A lifting equipment drive, as described in DE-A 38 40 281, is made up of independent units which can be disassembled as modular units. These consist of a planetary transmission with driving disc, a brake housing serving as a stator containing an emergency brake and of an electric motor.
In order to reduce noise emissions, the lifting equipment drive described in EP-A 0 442 882 has a planetary transmission whose input planetary gear set is helical cut whilst the second planetary gear set is straight cut. The input shaft is divided by a coupling between the sun gear of the input planetary gear set and the brake, installed between the electric motor and the planetary transmission. The portion of the shaft connected to the brake disc is mounted in a flange on the brake housing by means of a radial ball bearing. The other part of the input shaft which carries the sun gear is mounted with a further radial grooved ball bearing 33 in the planetary gear carrier (hub carrier) of the second planetary gear set. With this transmission, the fact that the input shaft is split into two can be seen as a disadvantage. This increases design and construction costs and the axial length of the drive unit.
In the field of drive technology, there is an increasing trend towards electric asynchronous motors, which are speed-variable due to a frequency rectifier. For lifting equipment applications, asynchronous motors operate within a speed range of approximately 1,500-2,600 rpm. This has the advantage that lift drive speeds of 0.6-2.5 m/sec can be achieved simply, i.e. without modifying transmission ratios.
Through the use of speed-variable asynchronous motors, speeds are achieved (e.g. 1,700-1,800 rpm) where low frequency vibrations occur, caused by the engagement frequency between the first and second planetary gear sets. These low frequency excitations and the harmonics create a humming noise in the lift by transmission of structure-born noise via air vibrations. These noises are felt to be very disturbing.
The fundamental task of the invention at hand, based on the state of technology as shown in the EP-A 0 442 882, is to further improve a lifting equipment drive, so that it is characterized by low design and construction costs, a reduced axial length and improved vibration or noise levels.
In accordance with the invention, the said task is solved by the sun gear being rotationally fixed to the free end of an input shaft, which is attached to the bearing of a fixed flange, and furthermore by the helical cut sun gear attached by a floating mounting to the hub carrier or the hub via a bearing which absorbs axial and radial forces.
The solution based on the invention can be executed with at least two different types of design. In the first design, the drive of the first planetary gear set is achieved via a longer input shaft and a helically cut second planetary gear set, which serves as a stationary transmission. The second design involves developing the drive using a shorter input shaft and another helically cut second planetary gear set which serves as epicyc
REFERENCES:
patent: 1786158 (1930-12-01), Hawes
patent: 3906818 (1975-09-01), Benthake et al.
patent: 4461460 (1984-07-01), Telford
patent: 4656890 (1987-04-01), Marquardt
"Mechanism and Dynamics of Machinery", Mabie&Reinholtz, p. 227, John Wiley&Sons Pub., 1987.
Mann Egon
Meisinger Erwin
Ta Khoi Q.
ZF Friedrichshafen AG
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