LINEAR HANDRAIL DRIVE

Abstract: A handrail drive (4) for an escalator or a moving sidewalk, characterized in that the handrail drive (4) is designed as an electrical linear drive (4) with a stationary primary part (12) and a moveable secondary part (14).

Description: Linear Handrail Drive Technical Field The invention concerns a linear handrail drive for an escalator or a moving sidewalk. Background of the Invention Conventional handrail drives for passenger conveyors such as escalators or moving sidewalks are also driven by the motor for the conveyor's tread area. Frequently one of the reversing wheels in the end areas of the balustrades is used as the handrail's drive wheel. Another common type of drive uses a circulating endless drive belt which for example contacts the inside of the handrail along a predetermined path, and presses against it in order to drive it. The drive belt itself is driven by the conveyor's motor via a drive pulley. Also known are drive types which receive their power from the tread area belt. The lengthy power transmission paths often lead to an irregular or a jerky movement of the handrail. It is furthermore difficult to adjust the handrail speed to the exact speed of the tread area. Add to that the increased wear of the handrail or the drive belt, especially due to the frictional interaction with the driven power wheel. This requires relatively frequent replacements of the typical wearing parts and additionally leads to undesirable downtime for the passenger conveyor, and to associated costs. Disclosure of the Invention It is the task of the present invention to make available a handrail drive which provides uniformity to the handrail drive and causes less wear. This is achieved by the invention in that the handrail drive is designed as an electrical linear drive with a stationary primary part and a moveable secondary part. Thus the handrail of a conveyor is provided with its own drive, which eliminates the long power transmission paths and their associated disadvantages. In addition the linear movement of the drive can easily be translated into the circulating movement of the handrail without requiring an abrasion-intensive power transmission path between a drive wheel and the handrail for example. The "primary part" and "secondary part" concepts of the invention are used in the sense of a first and a second part and have no significance with respect to the special construction of the linear drive, for example in the sense of an excitation system and a conductor system. A distributed arrangement of several such handrail drives in different areas of the handrail's moving path can ensure a uniform movement of the handrail, particularly with long handrail lengths. The secondary part of the linear drive is preferably located on the handrail and its integration therein is especially preferred. The inside of the handrail in particular, i.e. the area of the handrail which opposes its hand support area, is a suitable place for installing the secondary part. With this type of handrail drive, the driving forces are produced directly on the handrail and the latter therefore requires no frictional power transmission. In the ideal case there is no wear caused by driving the handrail . As an alternative, the secondary part can be located in a circulating drive belt which acts in combination with the handrail to drive the latter. However this type of handrail drive requires a frictional power transmission from the drive belt to the handrail, and therefore leads to a certain amount of wear in the area where this frictional contact with the handrail or the drive belt takes place. However this type of construction avoids the primary source of wear in the transition between the drive wheel and the drive belt, or the handrail. The drive belt acts in combination with the handrail in a partial area where it is guided over separate deflection pulleys to close off the moving path of /10902 the drive belt; it is also possible however to let the drive belt run parallel to the handrail along its entire length and also to guide it around the reversing wheels of the handrail. It is generally advantageous to choose a material with a high coefficient of friction for the drive belt in the area where it acts in combination with the handrail. In cases where the drive belt runs parallel to the handrail along its entire length, a material with particularly good adhesion characteristics can be an advantage. In extreme cases an adhesive is used to attach the drive belt to the handrail. The linear drive preferably has an excitation system that is composed of permanent magnets. In that case a multipolar permanent magnet linear drive is especially preferred. This could also be an excitation system with coils supplied with direct current, or an excitation system with coils supplied with alternating or three-phase current, where the excitation system produces a time- variable magnetic field for example. Preferably the excitation system and the permanent magnets in particular are provided in the secondary part. The use of permanent magnets as an excitation system in the secondary part has the decisive advantage of offering a particularly simple and space-saving solution. The moveable secondary part particularly requires no power supply for any type of coils. The linear drive preferably has a conductor system, where the speed of the linear drive is governed by a controller which controls a time- variable magnetic field of the conductor system. The conductor system is preferably located in the stationary primary part. The conductor system may have coils with wound coil cores. These may consist of a laminated material and are preferably interconnected at the end of their base. The current flowing through the conductor system and the excitation system's magnetic field produces a directed force which generates a relative movement between the primary and the secondary parts. A continuous drive is produced in that the current flowing through the conductor system is controlled as a function of its relative position with respect to the excitation system's magnetic field. This control allows to manage the speed of the linear drive. The controller preferably controls the synchronism of the handrail with the tread area of the escalator or the moving sidewalk, in response to speed signals from the tread area of the escalator or the moving sidewalk. These signals are received by a sensor for example, and are relayed to the controller. A very precise synchronous control can be established in this way between the tread area and the handrail. In the case where the handrail is driven by the drive belt an additional speed sensor, which detects the speed of the handrail, can compensate for a possible slippage of the drive belt with respect to the handrail. The controller evaluates the corresponding sensor data and converts them into control data for the linear drive. It is preferred if the surface of the primary part facing the secondary part, or the surface of the secondary part facing the primary part, is provided with a friction-reducing coating. In the case where the secondary device is integrated into the handrail, this can take place by locating the secondary device under the usual antifriction layer on the inside of the handrail. It is preferable to provide two primary parts where one of them is located on one side of the secondary part and the other on the other side of the secondary part. This kind of sandwich arrangement which places the secondary part between two primary parts makes it possible to create a large driving force on a short length of the secondary part. The two primary parts can either be parts that are separated from each other, or they can be connected to a yoke bridge, or they may be constructed in one piece. It is preferred if the secondary part is equipped with a device that essentially causes the distance between the primary part and the secondary part to remain constant. This distance or the air gap between the primary part and the secondary part affects the driving force which the linear drive is capable of producing. Such a device is preferred in this case in order to essentially eliminate any fluctuations which in turn could lead to a jerky operation of the handrail. This defines the driving force of the linear drive to a higher degree and allows to design the linear drive in smaller size which contributes to a cost reduction. The special feature of the electrical linear drive is its elongated construction which is particularly suited for use as a handrail drive. Typical space problems, such as often occur with conventional handrail drives, do not take place with an electrical linear drive. The electrical linear drive can even be installed in the visible area of glass balustrades without attracting any undue attention. The electrical linear drive can generally be installed in the most diverse areas along the handrail path, for example in the area where the handrail is grasped by the passengers, or in the handrail's return area, or even in the reversing areas. The invention also concerns an escalator or a moving sidewalk which has a handrail drive according to the present invention, as well as a handrail equipped with a secondary part for a linear handrail drive according to the present invention. Brief Description of the Drawings The invention will now be explained in greater detail by means of a configuration example illustrated by drawings wherein: Fig. 1 is a first configuration of a handrail drive according to the present invention in which parts of the handrail have been removed for a clearer view; Fig. 2 is a cross section of a handrail which integrates a part of the linear drive of the first configuration; Fig. 3 is a schematic illustration of a second configuration of a handrail drive; and Fig. 4 is an enlarged illustration of a cross section of part of a drive belt with the configuration according to Fig. 3. Best Mode for Carrying Out the Invention Reference is made to Fig. 1. It shows a handrail 2 and a handrail drive 4. As can be seen in Fig. 2, the cross section of the handrail is essentially C-shaped, where the handrail area 6 has been flattened and the bent edge areas 8 and 10 which continue on both sides, are used to clasp a not illustrated handrail guide. Fig. 1 shows the handrail with its hand support area 6 facing downward, and part of the bent edge area 8 which is closer to the viewer has been cut away for clearer illustration. The handrail drive 4 is a linear drive with a stationary primary part 12 and a moveable secondary part 14, which is formed in one piece with the handrail in the illustrated configuration. The secondary part is essentially composed of permanent magnets 16, 18 made of a high-grade magnetic material, whose north and south poles are respectively arranged upward in the lengthwise direction of the handrail 2, and alternate relatively closely under the surface of the inside 20 of the handrail 2. As large a number of permanent magnets 16, 18 as possible is provided and they closely follow each other in the lengthwise direction of the handrail. The more and the smaller the permanent magnets 16, 18 are and the closer they follow each other, the smoother and more uniform is the driving characteristic of the linear drive 4. In the transverse direction of the handrail 2 they extend essentially across the entire width of the inside 20. Their length is at a maximum in the lengthwise direction of the handrail 2, so that the hard material of the permanent magnets 16, 18 does not affect the flexibility of the handrail 2. In an escalator or a moving sidewalk, the primary part 12 is stationary and is attached to its frame for example. The primary part 12 is a long comb-like element in which individual teeth 22, 24 are provided which form electromagnets with wound coils. The width of the primary part 12 is preferably somewhat smaller than the width of the opening area between the two bent edge areas 8, 10 of the handrail 2. In this way the inside surface can be optimally used to produce the driving force for the handrail 2. The side surfaces of the primary part 12, together with the bent edge areas 8, 10 can be used to guide the handrail 2 in the lateral direction. The primary part's body which supports the coil windings consists preferably of an easily remagnetized soft metal and particularly has a laminated construction of individual sheet metals. The base 6 of the primary part's body is solid throughout. The stationary primary part 12 can either be straight as shown and can be attached to the escalator or to the moving sidewalk in the straight areas of the handrail 2. However it can also be provided in bent form for areas where the handrail 2 is not straight but runs along an arc, as is the case in the reversing areas for example. The primary part 12 is provided with a friction-reducing coating on the surface that faces the inside of the handrail. As can be seen in Fig. 2, a friction- reducing coating is also provided on the inside 20 of the handrail 2 over the permanent magnets 16, so that the handrail 2 with the secondary part 14 can move at a low friction against the primary part 12. The thickness of the two friction- reducing coatings as well as possibly the depth of the permanent magnets embedded in the handrail 2 determine the gap between the teeth 22, 24 of the primary part and the permanent magnets 16, 18 of the secondary part 14. The driving force of the linear handrail drive 4 depends essentially on the size of this gap. To ensure that the handrail 2 is held against the primary part 12 along its entire length, a (not illustrated) device can be provided which holds the handrail 2 against the primary part 12. Idle running rollers can therefore be provided for example, which press against the hand support area 6 and prevent the handrail 2 from moving away from the primary part 12. Depending on the configuration, this device can be built so that an air gap of a predetermined width is maintained between the handrail 2 and the primary part 12. Referring to Figs. 3 and 4 an alternative configuration of the handrail drive 4 of the invention will now be described. Figs. 3 and 4 use the same reference numbers as the corresponding parts in Figs. 1 and 2. The same things that were explained in connection with Figs. 1 and 2 basically apply to these parts. In Fig. 3 /10902 we therefore recognize the handrail 2 with a hand support area 6 and an inside 20. The bent edge areas 8 and 10 of Figs. 1 and 2 have been omitted to simplify the illustration. A circulating drive belt 30 acts on the inside 20 of the handrail 2 and forms the secondary part 14 of the linear handrail drive 4. Fig. 4 shows that permanent magnets 16, 18 are embedded in this belt. The drive belt 30 runs around two idle deflection rollers 32, 34 and its lower inside area shown in Fig. 3 acts in combination with the stationary primary part 12. The inside 20 of the drive belt 30 is preferably provided with a friction-reducing coating which together with the friction-reducing coating on the opposite surface of the primary part 12 ensures low friction losses. The drive belt 30 is preferably guided by a not illustrated lateral guidance device so that it cannot swerve sideways, particularly in relation to the stationary primary part 12. A device can also be provided to hold the drive belt 30 against the stationary primary part 12, or to maintain a constant air gap between them. The outside of the drive belt 30, i.e. the side of the drive belt 30 which acts on the inside 20 of the handrail 2 to drive it, preferably has a relatively high coefficient of friction to prevent any slippage of the drive belt on the inside 20 of the handrail 2, thereby causing any increase in its wear. In addition the shown configuration has pressure rollers 36, 38, 40 in the inside of the drive belt 30, which press the drive belt 30 against the inside 20 of the handrail 2. This also reinforces the frictional effect between the drive belt 30 and the handrail 2. The drive belt 30 is made of a flexible material, for example a plastic material which like a handrail can be provided with reinforcing strands or a reinforcing fabric in the lengthwise direction to increase its strength. To increase the driving force of the linear handrail drive 4, the stationary primary part 12 can be provided with a second stationary primary part on the drive belt 14 or the handrail 2, in an essentially symmetrical mirror-fashion. In this way the driving force can be doubled for the same length of the linear handrail drive 4. In addition to the pressure rollers 36, 38, 40 shown in Fig. 3, or as an alternative thereto, pressure rollers can be provided to act on the hand support area 6 of handrail 2 and press it against the drive belt 30. The lengthwise section in Fig. 4 shows permanent magnets 16, 18 in the drive belt 30, which form the secondary part 14 of the linear handrail drive 4. The letters N and S on the permanent magnets 16, 18 designate their north or their south poles. The alternating arrangement of the permanent magnets 16, 18 in the lengthwise direction of the secondary part 14 can be seen.

Claims: Patent claims 1. A handrail drive (4) for an escalator or a moving sidewalk, characterized in that the handrail drive (4) is designed as an electrical linear drive (4) with a stationary primary part (12) and a moveable secondary part (14). 2. A handrail drive (4) as claimed in claim 1, characterized in that the secondary part (14) is located on the handrail (2). 3. A handrail drive (4) as claimed in claim 2, characterized in that the secondary part (14) is located on the inside (20) of the handrail (2) which opposes the hand support area (6). 4. A handrail drive (4) as claimed in claim 1, characterized in that the secondary part (14) is located on a circulating drive belt (30) which acts in combination with the handrail (2) in order to drive it. 5. A handrail drive (4) as claimed in one of the preceding claims, characterized in that the linear drive (4) contains an excitation system which is formed of permanent magnets (16; 18). 6. A handrail drive (4) as claimed in claim 5, characterized in that the permanent magnets (16; 18) are located on the secondary part (14). 7. A handrail drive (4) as claimed in one of the preceding claims, characterized in that the linear drive (4) has a conductor system where the speed of the linear drive can be controlled by a controller which governs a time-variable current flow in the conductor system. O 00/10902 8. A handrail drive (4) as claimed in one of the preceding claims, characterized in that the controller controls the synchronism between the handrail (2) and the tread area of the escalator or the moving sidewalk as a function of their speed signals. 9. A handrail drive (4) as claimed in one of the preceding claims, characterized in that a friction-reducing coating is provided on the surface of the primary part (12) which faces the secondary part (14). 10. A handrail drive (4) as claimed in one of the preceding claims, characterized in that a friction-reducing coating is provided on the surface of the secondary part (14) which faces the primary part (12). 11. A handrail drive (4) as claimed in one of the preceding claims, characterized in that two primary parts (12) are provided, one of which is located on one side of 5 the secondary part (14) and the other is located on the other side of the secondary part (14). 12. A handrail drive (4) as claimed in one of the preceding claims, characterized in that the secondary part (14) is provided with a device which essentially causes the o gap between the primary part ( 12) and the secondary part ( 14) to remain constant. 13. An escalator or a moving sidewalk equipped with a handrail drive (4) as claimed in one of the preceding claims. 5 14. A handrail (2), characterized in that it is provided with a secondary part (14) for a linear handrail drive (4) as claimed in one of the preceding claims.

Inventors: KRUSE MICHAEL, SEEHAUSEN KLAUS, STOXEN OLIVER, THALER DIETMAR, KRUSE, MICHAEL, SEEHAUSEN, KLAUS, STOXEN, OLIVER, THALER, DIETMAR
Applicants: OTIS ELEVATOR CO, OTIS ELEVATOR COMPANY
Application year: 1999
Main classification: B66B23
IPC codes: B66B23