Driving system for passenger transportation

A driving and/or reversing system includes a driving and/or reversing element and a chain having a plurality of first and second chain pins connected by chain plates. The driving and/or reversing element has first and second pitch circles. First and second chain pins are alternately correspondingly engaged with the first and second pitch circles.

The present invention relates to a driving and/or reversing element for a chain, in particular a driving and/or transporting chain of a continuous transporter for the transportation of persons or passengers and their hand baggage.

BACKGROUND OF THE INVENTION

Today, chains in countless variants are used in the construction of machines and systems as, for example, drive chains of continuous transporters for the transportation of persons, in particular of escalators, conveyors, and moving walks.

Driving elements drive the chain or step chain or pallet chain in the direction of circulation, while by means of rotation reversing elements transfer their individual translatory belt segments into each other. Preferably, but not necessarily, driving elements and reversing elements coincide and are executed in the form of, for example, chain wheels or wedge disks. Accordingly, now follows a short discussion of such engagement elements that engage with the chain or step chain by positive and/or non-positive engagement with the chain or step chain which they drive and/or reverse.

The engagement elements cause fluctuations in the speed of the chain strand in the longitudinal direction (i.e. in the direction of movement of the chain) and in the normal transverse direction thereto as a result of the so-called polygon effect. This results from the reversal of the individual chain links when running onto the chain wheel or engagement element. When this happens, the chain links experience a sudden acceleration perpendicular to the direction of circulation of the chain strand, because the individual chain links suffer a sudden rotational impulse—a running-in jerk or running-in thrust. Conversely, on running out, this rotational impulse causes the chain to roll in in the direction of rotation of the engagement element.

For a fuller understanding of the polygon effect, which as a result of induced vibrations is the main source of noise generation on maintained chains, causes them to wear, and, on people transporters, is experienced by the passengers as an unpleasant irregularity of motion, reference should be made to the relevant specialized literature, for example P. Fritz: Dynamik schnelllaufender Kettentriebe, VDI-Verlag, 1998, to which reference in its entirety is made.

With a conventional engagement element100, illustrated diagrammatically inFIG. 1, a chain200runs into the pitch circle500tangentially in such manner that the chain pins300subsequently run on the pitch circle500with radius R500. When, as shown in idealized form inFIG. 1, a pin in a vertical plane (shown dotted) enters for the first time into engagement with the element100, from that point on the pin is forced to travel with a velocity v=R500×ω, where ω is the constant speed of rotation of the engagement element. Its velocity L=v×cos(α) in the longitudinal direction of the loaded end (in the drawn plane ofFIG. 1, horizontal) reduces as angle α increases. Correspondingly, the loaded end is moved with this reducing horizontal speed L until the next pin300enters into engagement with element100and is suddenly accelerated to v. This results in the periodically fluctuating end velocity L=R500×ω×cos (α).

To avoid the polygon effect, WO 00/07924 proposes, as shown diagrammatically inFIG. 2, to gradually transfer the chain pins310from a smaller active circle (shown vertically dotted inFIG. 2), onto which the chain210runs tangentially, over a partially curved guide rail (not shown) onto the larger pitch circle510(shown dotted at angle α inFIG. 2). Simplified, should the radius r, on which the running-in chain pin310is guided, increase in the ratio r (α)=R500/cos (α), a constant end velocity L=R500×ω can be generated, while the velocity of the chain pin w increases correspondingly to w=R510×ω.

The engagement element is executed as a chain wheel110with constant pitch circle510. It can be regarded as disadvantageous that the chain rollers in the area of the curved guiderails are lifted off the tooth bases of the chain wheel, i.e. they drift on the pitch circle relative to the engagement element, which causes generation of noise as well as premature wear. Shown by way of explanation inFIG. 2is the engagement situation in which the chain pin310runs onto the tooth base at its lowest point. In this simplified illustration, the earlier start of engagement resulting from real contact geometry is ignored without the basic principles being affected. As can be seen by reference to the tooth spaces in the left part of the drawing, the chain pin310passes from the smaller active circle to the larger pitch circle510and thereby slides upwards within the tooth space relative to the teeth of the chain wheel110.

BRIEF DESCRIPTION OF THE INVENTION

A purpose of the present invention is therefore to provide a driving and/or reversing element for a chain or step chain or pallet chain that has no polygon effect.

A further purpose of the invention is to provide a driving and/or reversing element that induces only a slight impulse and avoids the disadvantages of conventional driving/reversing elements.

According to the invention, the engagement element or chain wheel has a first pitch circle and a second pitch circle with different diameters such that first chain pins on the first pitch circle and second chain pins on the second pitch circle alternately enter into engagement, or are engaged, with the engagement element. “Alternately” relates to an arbitrarily predefined sequence of chain pins that can come alternately or mixed into engagement with the engagement element.

It is preferable for a chain pin to enter into engagement on one of the pitch circles and the following chain pin of the chain to enter into engagement on the other pitch circle (sequence 1-2-1-2 . . . ).

It is, however, also possible that not only a first, but also one or more directly following chain pins of the chain enter into engagement on the first pitch circle and only then one or more following chain pins engage on the second pitch circle. In the case of two successive chain pins on the first pitch circle and two following chain pins on the second pitch circle that follow after these, a following sequence results: 1-1-2-2-1-1-2-2 . . . . Similarly, in the case of three successive chain pins on the first pitch circle and three chain pins on the second pitch circle that follow after these, the following sequence results: 1-1-1-2-2-2-1-1-1-2-2-2 . . . . Self-evidently, irregular sequences are also possible where, for example, two successive chain pins on a first pitch circle are followed by only one single chain pin on the second pitch circle (sequence: 1-1-2-1-1-2 . . . ) or vice versa, where one single chain pin on a first pitch circle is followed by two chain pins on the second pitch circle (sequence: 1-2-2-1-2-2 . . . ). With knowledge of the present invention, arbitrary other sequences and combinations of first and second chain pins are possible that eliminate the polygon effect.

The similarity of this principle to the way in which the disclosure of WO 00/07924 works is shown greatly simplified inFIG. 3. Engagement of a chain pin3A on the outer pitch circle6results in the same effect as in WO 00/07924, i.e. as a result of the smaller pitch circle radius, the following chain pin3B is drawn in with constant loaded end speed L. However, on engagement of this chain pin3B with the engagement element, contrary to WO 00/07924 it remains on the smaller pitch circle5. Since the next chain pin3C is again raised onto the larger pitch circle6, the pin3C experiences, in addition to its longitudinal velocity, a vertical component such that its total velocity, i.e. the velocity with which the loaded end is pulled in, increases. As a result of the reduction of the longitudinal component of the velocity of the chain pin3B that is explained in relation toFIG. 1, the reduction of the loaded-end velocity can be compensated for. The chain pin3C is accelerated to the velocity of rotation of the larger pitch circle6with which it then engages (as shown diagrammatically inFIG. 3).

Thus, while in WO 00/07924 each chain pin initially engages with the smaller active circle and then slides into the tooth space on the larger pitch circle, according to the present invention the chain pins engage alternately in different pitch circles. They therefore do not slide outwards or upwards relative to the engagement element or chain wheel but remain in the different pitch circles, which reduces wear and abrasion as well as the noise that occurs as a result of the relative movement between the chain pins and the engagement element.

In a preferred embodiment, during the entire reversal the chain pins rest on the tooth bases of the engagement element, embodied as a chain wheel. This results not only in a more stable guidance but also damps and reduces perpendicular and vertical oscillations of the chain.

Through reduction or elimination of the polygon effect, the noise and wear behavior of a chain drive with engagement elements according to the invention is greatly improved. Since the polygon effect is approximately proportional to the chain pitch (distance between the chain pins), as a result of the reduced or eliminated polygon effect larger pitches or smaller engagement element diameters or chain wheel diameters can be realized. The diameter of a chain wheels is proportional to the number of teeth, i.e. directly proportional to the pitch, so larger pitches mean fewer teeth and simpler or more simply manufacturable chain wheels. This results in advantages with respect to material outlay, fabrication, and series production.

It is preferable for the chain pins to incorporate chain rollers or steel rollers or plastic rollers or bushings that are borne rotatably in a manner that itself is known and through which they engage with the engagement element. When hereafter reference is made to chain pins, the reference includes these surrounding chain rollers or chain bushings which, as a result of the rolling instead of sliding friction, contribute to reducing friction and wear.

As already stated above in the explanation of the basic principle, in a preferred embodiment of the present invention the engagement element is executed as a chain wheel with toothing in which the chain pins engage in the tooth spaces of the chain wheel. This allows positive and reliable engagement between the chain pin and the engagement element. It is advantageous for the toothing to have alternately first tooth spaces on the first pitch circle and second tooth spaces on the second pitch circle. “Alternately” relates to an arbitrarily predefined sequence of tooth spaces that can be arranged alternately or mixed in an arbitrary sequence.

In an alternative embodiment, the engagement element can be executed equally well as a wedge wheel pair, the chain pins coming into positive contact with the wedge wheels. To form the different pitch circles, the wedge wheels can have alternating first areas with a first wedge angle and second areas with a second wedge angle different from the first wedge angle, the first pitch circle being defined by the contact points of the first chain pins with the first areas and the second pitch circle by the contact points of the second chain pins with the second areas. Although on the one hand wedge wheels require a minimum press-on force to create the necessary positive engagement, on the other hand they allow stepless setting of different reversal radii and driving ratios with the same driving units without additional gears or step gears.

According to the invention, at least two different pitch circles are provided onto which the chain pins alternately run. However, an engagement element according to the invention can have a third pitch circle such that first chain pins run on the first pitch circle, second chain pins run on the second pitch circle, and third chain pins run on the third pitch circle are alternately engaged with the engagement element. The third or also further pitch circles thereby can represent intermediate steps that allow a finer division of the chain while retaining the basic principle of the alternating pitch circles.

In a particularly preferred embodiment of the present invention, an engagement element embraces a first and/or a second guiderail that guides the first or second chain pin respectively on the first or second pitch circle. In particular, the guiderail that guides the chain pins on the larger pitch circle imparts to those chain pins an additional vertical velocity perpendicular to the longitudinal velocity and thereby compensates the reducing longitudinal component of the preceding chain pin. The chain pins can, however, be equally well guided only by the engagement element itself, for example the tooth spaces of a chain wheel on the corresponding pitch circle. In such a case, a small polygon effect may remain that depends on the geometry but which is, however, substantially reduced in comparison with conventional systems. Sliding of the chain pins relative to the engagement element can thereby be further prevented. Depending on the contact geometry, such relative sliding need not be completely avoided, but is reduced in principle through its occurrence on different pitch circles.

In a further development of the above particularly preferred embodiment, the first and second guiderails respectively guide the first and second chain pin respectively on the first and second pitch circle until they become disengaged from the engagement element. Rolling-in of the chain can thereby be avoided or at least reduced. In addition, sliding of the chain pins relative to the engagement element is thereby also reduced or entirely eliminated.

In an engagement element according to the invention, guidance of the chain pins on the pitch circle as described above is preferably realized in a manner that in itself is known in that the first and/or second chain pins respectively run on the first and second guiderails respectively. In a particularly advantageous further development of the present invention, a guide is provided in the plane of circulation of the chain strand that is divided into two halves, a first half forming the first guiderail and a second half opposite to it forming the second guiderail. On the first half of the facing side, the first chain pins have a larger diameter, particularly for a first chain roller, and therefore run on the first guiderail, while similarly the second chain pins on the opposite side have a smaller diameter, in particular for a second chain roller and therefore run on the second guiderail.

To avoid additional excitement in the perpendicular or vertical direction, an engagement element according to the invention is preferably embodied in such manner that the chain runs tangentially onto and off of the first and/or second pitch circle.

DETAILED DESCRIPTION OF THE INVENTION

The invention is explained in greater detail as follows by reference to a chain wheel. The invention can, however, be equally well realized by means of other engagement elements, in particular the already mentioned wedge-wheel pair, toroid pair, or similar gears or machine components.

FIG. 4shows an engagement element according to the present invention in the form of a chain wheel1viewed from a side. The opposite side of the engagement element is shown in unfilled outline.

The chain wheel1reverses the chain2between an upper loaded portion and a lower unloaded portion through an angle of 180° and by means of a drive for the engagement element (not shown). The reversal angle and angle of wrap, as well as the entry and exit directions, are purely exemplary, other angles and directions can be equally well realized with engagement elements according to the invention.

The chain wheel has a first pitch circle5and a second pitch circle6with different diameters. In the exemplary embodiment, by way of example the second pitch circle diameter is the larger of the two. The chain wheel can, for example, be embodied as an involute gearing7with alternating tooth space depths, first tooth spaces8A,8C, etc., defining the first pitch circle5and second tooth spaces8B,8D, etc., defining the second pitch circle6, which pitch circles are executed at different radial distances from the axis or middle of the chain wheel, but otherwise have similar or identical toothing geometry (as regards, for example, undercut, head-rounding, and the like).

The chain2includes chain pins that have mounted on them rotatable or slidable or swivelable chain rollers, runners or chain runners3A,3B,3C,3D, etc., that are joined to each other via chain plates or links4. A first set of chain3A,3C, etc., are mounted to a first side of the corresponding chain pins, while a second set of chain rollers3B,3D, etc., alternates with the first set and are mounted to a second side of the corresponding chain pins.

By means of a first guide rail9arranged on the first side of the midline plane of the chain and the engagement element (inFIG. 4, below the plane of the drawing and therefore shown in outline), on which the first chain rollers3A,3C run, these first chain rollers and corresponding pins are guided tangentially to the first pitch circle5and from the vertical middle plane of the engagement element1are engaged with the latter. They thereby experience a constant circumferential velocity v=R5×ω, where R5is the radius of the first pitch circle5and ω the rotational velocity of the chain wheel1.

Arranged in similar manner on the opposite second side of the midline plane adjacent to the engagement element1is a second guiderail10on which the second chain roller3B,3D and corresponding pins run and to which the second pitch circle6is tangentially guided so that, from the vertical middle plane of the engagement element1, the rollers are engaged with the latter. They thereby experience a constant circumferential velocity w=R6×ω, where R6is the radius of the second pitch circle6.

In a (not shown) further embodiment of the present invention, inside the chain plates4the chain pins may have continuous or divided chain rollers3A,3B,3C,3D, etc. The first chain rollers3A,3C project to the first side, the second chain rollers3B,3D to the second side. They run on the first and second guiderails9and10respectively.

In the exemplary embodiment shown, the alternating first and second tooth spaces8A,8C and8B,8D respectively are successively fitted with first and second chain rollers3A,3B,3C,3D respectively. By means of the guide rails9,10, these come tangentially into engagement with the respective pitch circle5or6without consequently sliding or moving within the tooth spaces. Advantageously, they rest consecutively on the tooth base and thereby reduce vertical or perpendicular vibrations upwards or downwards relative to the direction of travel of the chain strand2.

As already explained in principle in relation toFIG. 3, the inner chain pins3A,3C are pulled into the chain wheel by the respective preceding outer chain pin3B,3D with constant longitudinal velocity on the first guiderail9, since the preceding outer chain pins3B,3D are reversed on the outer pitch circle6. Conversely, through being brought onto the outer pitch circle6, the outer chain pins3B,3D are also accelerated in the vertical direction so that their total velocity along the guiderail(s)6remains constant although the longitudinal component of the inner chain pins3A and3C that pulls them reduces as the rotation of the chain wheel increases. The polygon effect is thereby prevented or greatly reduced.

FIGS. 5A and 5Billustrate the invention in which the driving and/or reversing element is embodied as a wedge wheel pair, the chain pins or rollers coming into positive contact with the wedge wheels. Each of the wedge wheels have alternately first areas with a first wedge angle and second areas with a different second wedge angle. First pitch circle5is defined by the contact points of the first chain pins with the first areas between the corresponding wedges of the wedge wheels while second pitch circle6is defined by the contact points of the second chain pins with the second areas between the corresponding wedges.

FIG. 6depicts a construction in which engagement element1has three pitch circles5,6and11employed in a similar manner to the construction ofFIG. 4. The chain pins and rollers sequentially and alternately engage with one of the pitch circles. The engagement element may be of a stacked or multiple plate configuration to allow corresponding guiderails to be provided for each of the three pitch circles, while the chain pins and rollers are correspondingly divided.