PULLEY FOR GUIDING A BELT FOR CARRYING A CAR AND/OR A COUNTERWEIGHT OF AN ELEVATOR SYSTEM

Abstract

A pulley for guiding a belt for carrying a car and/or a counterweight of an elevator system has a plurality of peripheral, axially spaced channels for receiving ribs of the belt. Each of the channels has two opposing channel flanks for force transmission by frictional engagement with one of the ribs and a peripheral groove between the two channel flanks. A width of the groove is at least 25 percent of an axial spacing of the channels and at least 80 percent of a height of the channels.

Claims

1-14. (canceled)

15. A pulley for guiding a belt for carrying a car and/or a counterweight of an elevator system, the pulley comprising: the pulley having a lateral surface extending around a periphery of the pulley with a plurality of peripheral, axially spaced channels formed in the lateral surface for accommodating ribs of the belt; wherein each of the channels has two opposing channel flanks for force transmission by frictional engagement with one of the ribs and a peripheral groove between the two channel flanks; wherein a width of the groove is at least 25 percent of an axial spacing of the channels and at least 80 percent of a height of the channels; and wherein the two opposing channel flanks form a wedge-shaped profile of each of the channels and the channel flanks run in a straight line.

16. The pulley according to claim 15 wherein the width of the groove is between 1 mm and 3 mm.

17. The pulley according to claim 15 wherein the axial spacing of the channels is between 4 mm and 6 mm.

18. The pulley according to claim 15 wherein the height of the channels is between 2 mm and 3 mm.

19. The pulley according to claim 15 wherein a depth of the groove is greater than 0.5 mm.

20. The pulley according to claim 15 wherein a diameter of the pulley is between 52 mm and 150 mm.

21. The pulley according to claim 20 wherein the diameter of the pulley is between 80 mm and 100 mm.

22. The pulley according to claim 21 wherein the diameter of the pulley is 87 mm.

23. The pulley according to claim 15 wherein the groove has a rectangular cross section with corners of the groove being rounded.

24. The pulley according to claim 15 wherein the two opposing channel flanks are oriented at an angle of at least 90 degrees to one another.

25. The pulley according to claim 15 wherein the two opposing channel flanks are each planar.

26. The pulley according to claim 15 wherein the two opposing channel flanks are each curved.

27. The pulley according to claim 26 wherein a tangent angle of a tangent applied to the channel flanks relative to an axis of rotation of the pulley is at least 35 degrees.

28. A device for carrying a car and/or a counterweight of an elevator system, the device comprising: at least one belt having a plurality of ribs extending in a longitudinal direction of the belt; and at least one pulley according to claim 15, wherein the at least one belt at least partially wraps around the at least one pulley and each of the ribs is received by an associated one of the channels of the pulley.

29. The device according to claim 28 wherein the ribs and/or the channels are formed such that the ribs touch the at least one pulley exclusively on the channel flanks of the channels.

30. An elevator system comprising: an elevator car; a counterweight; and the device according to claim 28 wherein the car and/or the counterweight is carried by the at least one belt of the device.

31. A pulley for guiding a belt for carrying a car and/or a counterweight of an elevator system, the pulley comprising: the pulley having a lateral surface extending around a periphery of the pulley with a plurality of peripheral, axially spaced channels formed in the lateral surface for accommodating ribs of the belt, wherein an axial spacing of the channels is between 4 mm and 6 mm. wherein a diameter of the pulley is between 52 mm and 150 mm; wherein each of the channels has two opposing channel flanks for force transmission by frictional engagement with one of the ribs and a peripheral groove between the two channel flanks, wherein a width of the groove is between 1 mm and 3 mm, a height of the channels is between 2 mm and 3 mm, and a depth of the groove is greater than 0.5 mm; and wherein the two opposing channel flanks form a wedge-shaped profile of each of the channels and the channel flanks run in a straight line.

Description

DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 shows an elevator system according to one embodiment of the invention.

[0043] FIG. 2 shows a pulley from FIG. 1.

[0044] FIG. 3 shows a cross-sectional view of a portion of the pulley from FIG. 2.

[0045] FIG. 4 shows a diagram illustrating surface pressures for different diameters of the pulley from FIG. 2.

[0046] FIG. 5 shows a diagram representing a possible geometry of a curved channel flank according to an embodiment of the invention.

[0047] The drawings are merely schematic and not to scale. In the different drawings, identical reference signs denote identical or similar features.

DETAILED DESCRIPTION

[0048] FIG. 1 shows a highly simplified representation of an elevator system 100. The elevator system 100 comprises a car 102 and a counterweight 104 which are carried by a belt 106. For example, the two ends of the belt 106 are fixed to a shaft ceiling of the elevator system 100. Between its two ends, the belt 106 is guided over a counterweight pulley 108 from which the counterweight 104 is suspended, a traction sheave 110 coupled to a motor 112, a first car pulley 114 and a second car pulley 116. The two car pulleys 114, 116 are attached to the car 102. The counterweight pulley 108, the traction sheave 110, the first car pulley 114 and the second car pulley 116 are each designed as a pulley 118 with a special channel profile, as will be described in more detail below. By rotating the traction sheave 110, the belt 106 is moved in the direction of its longitudinal axis, as a result of which the heights of the elevator car 102 and of the counterweight 104 change. The driving force is applied by frictional engagement between the traction sheave 110 and the belt 106.

[0049] The pulleys 118 together with the belt 106 form a device 120 for carrying the car 102 and the counterweight 104. The device 120 may also comprise more than one belt 106.

[0050] Alternatively, the elevator system 100 may also be designed without the counterweight 104.

[0051] FIG. 2 shows a perspective view of a pulley 118 from FIG. 1. The pulley 118 may be rotated about an axis of rotation 200 and has a plurality of peripheral channels 202 spaced axially apart from one another on its lateral surface. A portion of the belt 106 is also shown, which is designed with a plurality of ribs 204 extending in the longitudinal direction of the belt 106. The ribs 204 each engage in one of the channels 202 in a region of the pulley 118 wrapped around by the belt 106. The contours of the channels 202 and the ribs 204 may be complementary to each other. For example, the channels 202 and the ribs 204 may each form a wedge-shaped profile.

[0052] A guide diameter D.sub.d of the pulley 118 is, for example, between 52 and 150 mm, in particular between 80 and 100 mm and preferably 87 mm.

[0053] FIG. 3 shows a cross-sectional view of a portion of the pulley 118 of FIG. 2. A profile of the channels 202 can be seen. Also shown is a portion of the belt 106 which engages in one of the channels 202 with one of its ribs 204.

[0054] Each of the channels 202 has two channel flanks 300 lying opposite one another. The channel flanks 300 are used for the frictional force transmission between the pulley 118 and the belt 106, wherein the ribs 204 each touch the channel flanks 300 with their rib flanks.

[0055] In this example, the channel flanks 300 run in a straight line and enclose a wedge or opening angle W of 90 degrees plus/minus 0.2 degrees. Alternatively, the channel flanks 300 may be designed in the shape of an arc, a segment of a circle or a semicircle, as shown in FIG. 5, and/or can be aligned at an opening angle W that differs from 90 degrees with respect to one another.

[0056] Between the two channel flanks 300 of a channel 202, there runs a groove 302 which forms a channel base of the channel 202 and undercuts the channel flanks 300. The groove 302 may completely encircle the pulley 118.

[0057] The channel profile is selected such that a width B of the groove 302 is at least 25 percent of an axial spacing A of the channels 202 and at least 80 percent of a height H of the channels 202. For example, as indicated in FIG. 3, the width B may be 2 mm, with a spacing A of 5 mm plus/minus 0.03 mm and a height H of 2.12 mm. However, as described above, numerous other combinations of A, B and H are also possible.

[0058] By dimensioning the groove 302 in this way, a projected height H′ of the channel flanks 300, and thus a contact surface of the ribs 204, at a given height H compared to an embodiment with a narrower groove (indicated with dashed lines) may be reduced to an extent relevant for a diagonal pull behavior of the belt 106.

[0059] A spacing A′ between a channel center of an outermost channel 202 and a front edge 304 of the pulley 118 is specified here as 7.5 mm, for example.

[0060] A depth T of the groove 302 may be greater than 0.5 mm. In FIG. 3, the depth T is about 1 mm.

[0061] As shown by way of example in FIG. 3, the groove 302 may have a rectangular cross section. The corners of the groove 302 may be rounded.

[0062] It can also be seen in FIG. 3 that the ribs 204 together with the grooves 302 each enclose a cavity 306, i.e. the ribs 204 do not touch a respective base of the grooves 302 when the belt 106 is loaded. The force transmission therefore takes place exclusively via the channel flanks 300.

[0063] FIG. 4 uses a diagram to illustrate the influence of the width B on a surface pressure p between the channel flanks 300 and the ribs 204. A scale of width B comprises values between 0 and 3 mm. Shown are a first curve 401, which represents the surface pressure p on a pulley 118 having a guide diameter D.sub.d of 87 mm, a second curve 402, which represents the surface pressure p on a pulley 118 having a guide diameter D.sub.d of 125 mm, and a third curve 403, which represents the surface pressure p on a pulley 118 having a guide diameter D.sub.d of 150 mm.

[0064] It can be seen that, in order to achieve a surface pressure p of approximately 5 MPa, a width B of 1 mm is required for D.sub.d = 87 mm, a width B of 1.8 mm is required for D.sub.d = 125 mm and a width B of 2.2 mm is required for D.sub.d = 150 mm.

[0065] FIG. 5 shows a diagram that illustrates a possible geometry of a curved channel flank 300. In addition, a curve is drawn that indicates a climbing angle K for each point of the channel flank 300, i.e. a tangent angle which encloses a tangent applied to this point with the axis of rotation 200 (here with an abscissa). The width B, starting from a central axis of the channel 202, is plotted on the abscissa. The central axis here corresponds to a left ordinate that intersects the abscissa at B = 0 and on which the height H is plotted. The climbing angle K or the opening angle W is plotted on a right-hand ordinate.

[0066] The climbing angle K may be interpreted as a measure of the tendency of the belt 106 to climb out of the channels 202 in the event of lateral forces. The larger the climbing angle K, i.e. the more steeply the channel flanks 300 rise, the lower the tendency of the belt 106 to climb. With a groove or an undercut with a width of B = 2 mm, a climbing angle K of about 40 degrees may be achieved, for example. On the other hand, a climbing angle K of only about 30 degrees may be achieved with a groove or an undercut with a width of B = 1 mm.

[0067] Finally, it should be noted that terms such as “comprising,” “including,” etc. do not exclude other elements or steps, and terms such as “a” or “an” do not exclude a plurality. Furthermore, it should be noted that features or steps that have been described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above.

[0068] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.