Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes control for power source of drive-means
Reexamination Certificate
2000-03-14
2001-10-23
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes control for power source of drive-means
C187S250000
Reexamination Certificate
active
06305501
ABSTRACT:
The present invention relates to an elevator and in particular, to a drive system for an elevator.
DESCRIPTION OF THE BACKGROUND ART
In elevator technology, several methods are used to produce the motive power for elevators. A common method is to use a traction sheave connected to a rotating motor hoisting the elevator car by means of ropes, with a counterweight placed on the opposite side of the traction sheave to balance the load. Another established solution is found in hydraulic elevators, in which the hoisting power to move the car is obtained from hydraulic cylinders either directly or via ropes. Most modern elevators are based on these solutions, of which many variations have been developed.
Although the above-mentioned elevator types have become established and are safe and reliable in operation, the solutions used in them comprise several factors that are objections of improvement and product development. For example, investigations are continuously being made to find ways of more effective utilisation of building space and reduction of energy consumption. For hydraulic elevators, the hoisting height is in practice limited to a few floors. By contrast, elevators with rope suspension have been installed in buildings as high as several hundred meters, in which case rope elongation and oscillation cause problems. Because of the rope suspension arrangements, the number of elevators in a shaft is practically limited to one.
In addition to rope-suspended and hydraulic elevators, several solutions for the use of a linear motor in an elevator have been proposed. In this case the electric motor is completely located in the shaft space. Most linear elevator motors have been based on the induction motor principle, although other motor types, such as a linear motor based on permanent magnets have also been presented. Several different solutions have been proposed, but as yet it has not been possible to produce a competitive elevator.
SUMMARY OF THE INVENTION
The object of the present invention is to achieve a new elevator in which several drawbacks encountered in prior art solutions are avoided.
The invention is based on a so-called switched reluctance linear motor or a variant developed from it, which makes use of the so-called microflux technique. In the switched reluctance motor, the windings of the linear motor are optionally placed either in a fixed primary circuit or in a movable secondary circuit. The motor is used to both move the car and support it by generating a force component in the direction of motion and a force component perpendicular to the direction of motion. The placement of the winding on the primary or secondary side can be selected separately for each application.
According to a preferred embodiment of the invention it is utilised the combined effect of a linear motor and pneumatic air gap regulation. The linear motor is used to both move the car and support it by generating a force component in the direction of motion and a force component perpendicular to the direction of motion. The air gap between the primary and secondary circuits of the linear motor is maintained by means of the perpendicular component and pressurised air.
According to a preferred embodiment of the invention, in a motor based on the microflux technique, called microflux motor, the windings are placed on both the primary and secondary sides, thus reducing the proportion of leakage flux and improving the power-to-weight ratio of the motor. The supply of current to the windings is so controlled that the magnetic flux will only pass through a minimal distance in the yoke part of the motor and that the flux loop will be completed in the first place via adjacent teeth.
According to a preferred embodiment, the power is supplied to the windings using control equipment disposed along the entire length of the track of the elevator and each winding is controlled separately. Alternatively, several windings can be combined to form a group with common control.
According to another alternative implementation of the invention, the pneumatic equipment comprises a source of pressurised air and a pipe system with nozzles, fitted substantially in the air gap between the primary and secondary circuits of the linear motor. The pressurised air keeps the air gap clean and generates a smooth air flow from the center of the air gap towards its edges.
The alternatives regarding the structural solutions of the invention are to dispose the linear motor and pneumatic equipment on one side of the elevator car or to dispose the linear motor and pneumatic equipment on two or more sides of the elevator car. The former solution provides more freedom regarding the placement of the elevator in the building and an independence of a traditional elevator shaft. The latter solution allows more freedom of variation of the physical dimensions of the elevator-specific motor.
In an embodiment of the invention relating especially to the structure of the linear motor, the tooth pitch of the primary and secondary circuits is effected by applying the vernier principle. The motor power can thus be uniformly distributed over the entire length of the active part of the motor, i.e. the movable secondary side.
According to a further embodiment, the primary circuit and/or secondary circuit is coated with a plastic film on the surface facing the air gap. The effective air gap of the linear motor can thus be adjusted without increasing the pneumatically regulated air gap at the same time.
The new type of motor solution of the invention provides several advantages in elevator technology. As the motor applies a lifting force directly to the elevator car, it eliminates the need for hoisting ropes, which are an object of regular maintenance and renewal. Readjustments due to rope elongation naturally become unnecessary. Correspondingly, no traction sheave and no diverting pulleys need to be installed. The counterweight and associated shaft equipment, such as counterweight guide rails, become superfluous. No separate machine room is needed, but the control and operating equipment can be placed in the elevator or in conjunction with the equipment at the landings. The travel of the elevator car in the elevator shaft is controlled by a pneumatic bearing system, so there are no conventional car guides and guide rails installed for them. Safety gears as used in current technology are also left out. The overall degree of utilisation of the elevator shaft is higher because the only equipment that needs to be installed in the elevator shaft in addition to the elevator car is the very flat magnetic circuits of the motor. The lifting height is unlimited without any special additional equipment or rigging necessitated by height.
The elevator can be implemented as a external installation in which the elevator climbs along the external wall of the building, thus allowing a further space saving inside the building. In the elevator solution of the invention it is further possible to use a light car construction because the magnitude of the friction does not limit the minimum car weight as in the case of traction sheave elevators. Based on the degrees of freedom of the elevator of the invention and the limitations of conventional elevators, this new solution provides advantages especially in the case of very high and very short elevator shafts. Furthermore, the elevator solution of the present invention makes it possible to develop multiple-car elevator shafts and also transport systems combining vertical and horizontal movement.
The switched reluctance motor has a considerably higher power-to-weight ratio than conventional motor solutions. In the microflux motor, the power-to-weight ratio can be further improved as compared even with the reluctance motor.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only
Kahkipuro Matti
Kallioniemi Antti
Pelto-Huikko Raimo
Birch & Stewart Kolasch & Birch, LLP
Kone Corporation
Salata Jonathan
LandOfFree
Elevator reluctance linear motor drive system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Elevator reluctance linear motor drive system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elevator reluctance linear motor drive system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2597932