WO2007090837A1

WO2007090837A1 - Variable-reduction traction transmission mechanism

Info

Publication number: WO2007090837A1
Application number: PCT/EP2007/051127
Authority: WO
Inventors: Jean-Marc Baggio
Original assignee: Ph.B Innovations Sarl
Priority date: 2006-02-06
Filing date: 2007-02-06
Publication date: 2007-08-16
Also published as: FR2897048B1; FR2897048A1

Abstract

Traction transmission mechanism using parallel flexible elements moving in the same direction, characterized in that it comprises a pulley (2, 3; 116) on which is wound a driven flexible element (6; 118) connected mechanically to a pulley (1; 112) from which is unwound a driving flexible element (7; 114), with a variable ratio of the linear speeds of the flexible elements and an anchoring point (124) at a fixed reference (128; 140). Preferably, the mechanism reaches an operating point where the pulleys no longer have a rotational movement and transmit the movement as direct drive, the ratio of the linear speeds of the flexible elements reaching the value of 1.

Description

VARIABLE DEMULTIPLICATION TRACTION TRANSMISSION MECHANISM

The present invention relates to the field of devices using flexible traction elements such as cables, chains or belts.

A problem that has only partially been solved is the lack of progressivity at start-up where significant efforts are needed to set the parts of these devices and related elements in motion.

Hoist or muffle systems are known that increase the traction force by decreasing the amplitude of the translation in a constant ratio.

It lacks a variable gearing system providing a progressivity of these startup efforts by distributing them during the setting in motion of the parts of the devices.

This goal is achieved by a mechanism of transmission of traction by elements

parallel hoses moving in the same direction having a pulley where a flexible led element is wound, mechanically connected to a pulley from which a flexible driving element is driven, with a variable speed ratio Linear flexible elements and an anchor point to a fixed reference. Each flexible element has an end attached to its respective pulley. To improve the movement of the parts of said apparatuses, it is advisable to have a high input speed, that of the translation of the flexible leading element, and to obtain a lower output speed, that of the translation. of the driven element, and therefore with a proportionally greater tensile force. This results in a smooth start and it is then necessary to gradually reduce the ratio between these

speeds to accelerate the output movement. This can be achieved by a variable mechanical transmission of rotation between the input and output pulleys, transmission known per se, or by the geometry of said pulleys. Indeed, a decrease in the instantaneous radius of the input pulley or an increase in the instantaneous radius of the output pulley generates the same effect of reducing the gear ratio and thus the acceleration of the output movement. These variations of instantaneous radius can be obtained by spiral profiles of the pulleys, but also with circular pulleys since the flexible elements can create this spiral by wrapping more than one turn by the successive addition of their thicknesses. This definition of spiral pulley by its profile or by the successive thicknesses of its flexible element which is wound therein is similar to that described in the French patent application 05 08771 of 26/08/05 not yet published. It will be noted that a pulley whose profile is spiral can operate at most on one turn, as opposed to that whose successive thicknesses ensure the radius variation which acts by essence on several revolutions The reduction between the linear velocities brings a difference between input traction and output traction which imposes an anchor point at a fixed reference where a reaction balancing the forces of input and output, reaction parallel to these and in the same direction as the input whose amplitude is less. The anchoring means is advantageously provided on the housing or frame which supports (contains) the mechanism.

In a particular embodiment of the invention, the ratio of the linear velocities of the flexible elements reaches at least once the value 1, with an alignment of the flexible input and output elements, making it possible to transmit the movement in direct contact with pulleys having no more rotational movement, but the same translational movement as the flexible elements and the entire mechanism. This results in a permanent phase with equal traction following the variable phase of reduction. As the mechanism must be anchored to a fixed reference during the first phase, it is necessary that this anchor is disengageable or, more simply, achieved by a support or attachment to a flexible element resistant to cash the reaction, but allowing a displacement in the direction of the final translation.

In the case of vertical handling, this reference is ideally the end of a flexible member of appropriate length whose other end is fixed to the upper structure of the lifting system. It is a good idea to allow this flexible reaction element to keep this length

appropriate by a low-voltage winching system related to displacement of the mechanism during the direct drive phase, and to be able to block it for use thereafter in fixed reference.

In a particular embodiment of the invention, the input and output pulleys are integral on the same axis of rotation and at least one of the pulleys is spiral by its profile or by the successive thicknesses of its flexible element, c that is, its instantaneous radius varies uniformly with its rotation. The rotational speeds of these pulleys are therefore equal at all times and the variable gear ratio is ensured by the variation of

instantaneous radius of the at least one spiral pulley. If the driving pulley is spiral, the driving flexible element must be fixed at the point of minimum radius and must be unrolled from the pulley, on the other hand if the driven pulley is spiral, then the flexible element driven must be wound and its fixation is also at the point of minimum radius. It is possible to arrange the two pulleys in a spiral, for a greater variation of the gear ratio. The anchoring point to the fixed reference of such a mechanism is then the common axis of the pulleys.

In a particular embodiment, one of the pulleys is doubled with an identical pulley with a corresponding parallel flexible element and these two pulleys are placed symmetrically with respect to the third pulley. This arrangement causes a balance in bending of the common axis, with two parallel flexible elements on either side of the third flexible element. Ideally, the led elements are doubled because they are more solicited because of the multiplication. Anchoring the common axis is then facilitated because only requiring immobilization thereof in the common direction of the flexible elements and in the opposite direction to the driving force, on either side of the rigid set of three pulleys. This is easily achieved by a double support on either side of this axis, or by a double attachment to the ends of two flexible elements of appropriate length whose other ends are fixed to a fixed reference, which may be to the upper structure lifting system in the case of vertical handling.

In a particular embodiment, the value 1 of the multiplication is

reached with the three flexible elements in the same plane. With three integral pulleys in rotation, this reduction of 1 is realized when the instantaneous rays have the same value, value obtained either by the profiles of the pulleys, or by the successive thicknesses of the flexible elements. An alignment of the three flexible elements is then obtained with ideally the elements carried symmetrical with respect to the driving element, in a perfectly balanced disposition. The permanent phase in direct engagement takes place with the block of three pulleys in common translation with the three flexible elements.

According to another aspect, the present invention also relates to a traction system, including lifting, comprising a flexible element capable of transmitting traction to an object, the traction force is transmitted to said object via a traction transmission mechanism such that defined above, attached to the flexible element of the traction system. Typically, the driving element of the traction transmission mechanism is securely attached (coupled) to the element

flexible traction system and the driving element of the mechanism is securely attached (coupled) to the object on which the traction is to be exerted, possibly by means of an intermediate hose or bar.

Other features and characteristics of the invention will become apparent from the detailed description of some advantageous embodiments presented below, by way of illustration, with reference to the accompanying drawings. These show:

FIG. 1: a block diagram of a first variant of the invention using spiral pulleys, in the initial configuration; FIG. 2: variant of FIG. 1 in direct drive configuration;

FIG. 3: a block diagram of a second variant of the invention using a spiral gear, in the starting position.

The present invention finds application in the field of appliances using flexible traction elements such as cables, chains or belts. This is for example the case of crane-type lifting and handling devices, which allow the lifting of a load by means of a wire rope.

A smooth start is essential for the safety and longevity of any mechanism and this is even more true in handling. The mechanism according to the invention aims at facilitating the lifting of a load with the aid of such a vertical lifting device.

According to one embodiment, the invention proposes a mechanism for transmitting traction by parallel flexible elements and moving in the same direction, which operates initially in a transient mode where the traction movement is multiplied to facilitate starting, and then reaches

a live mode. The mechanism includes:

a pulley where a flexible flexible element is wound;

a pulley from which a flexible driving element takes place;

the mechanism is designed so that the pulleys are mechanically linked with initially a variable ratio of the linear speeds, until reaching an operating point where the pulleys no longer have rotational movement and transmit the movement in direct drive, the ratio linear velocities of the flexible elements reaching the value 1;

the mechanism comprises an anchor point, for example on its frame, allowing its anchoring to a fixed reference during the initial phase.

This independent mechanism fits into the traction cable of the hoist, and simply requires a link to a fixed reference during the phase

initial, by means of anchoring. Thus, the flexible driving element is for example linked to a free end of the traction cable of the hoist and the driven flexible element can be directly attached to the load to be lifted, or by an intermediate cable. The free ends (opposite to the ends pulleys) flexible elements leading and driven can of course be provided with attachment means or coupling to be attached to the load or other flexible element.

By the design of the mechanism, the movement of the load will initially be increased, because of the variable speeds between the pulleys. This initial gearing allows lifting with improved starting traction. Then the mechanism will reach a point of direct drive operation, where the pulleys are no longer in motion and the leading and driven flexible elements will move at the same speed.

The mechanism according to the invention thus allows a better exploitation of the start-up pull-ups, and therefore of the drive couples, which also allows a consequent downsizing and energy savings.

The idea is therefore to interpose the mechanism in a lifting wiring, so that the force exerted by the lifting device, e.g. via its motor, on the flexible element driving to lift the load is in a first phase geared down by the mechanism, causing a slower lifting but with a higher traction load by the led element.

When the mechanism reaches the operating point in direct drive, the pulleys of the leading and driven hoses are no longer in rotation and the pulling force is simply transmitted between upstream and downstream of the mechanism. The mechanism therefore moves with and at the same speed as the traction wiring of the hoisting apparatus in which it is mounted. It should be noted that the reduction between the linear speeds, during the initial transient phase, causes a difference between input traction and output pull of the mechanism, and therefore imposes an anchoring means to a fixed reference where a reaction balancing the input and output efforts.

Figures 1 and 2 show a set of three spiral pulleys, a large driving pulley 1, framed by two small pulleys 2 and 3 conducted identical and symmetrical with respect to the first. These three pulleys are mounted integral in rotation on the axis 4 and carries two flexible elements 5 and 6 respectively fixed to the smallest radius of the driven pulleys and a flexible leading element 7 fixed to the smallest radius of the driving pulley. The invention is shown in the case of a vertical handling with the anchoring points at the ends of the axis 4 fixed to flexible elements of appropriate length attached to the upper structure not shown of the lifting system. These fixed references are symbolized by their reactions in the form of arrows 8 and 9. FIG. 1 describes the starting position of the variable phase with the maximum reduction ratio. All the pulleys have a ratio of 2.5 between maximum radius and minimum radius and the lifting force is thus at the beginning 6.25 times lower, the square of 2.5. To best use the rotation of these pulleys over a revolution, the minimum radius of the large pulley has the same value as the maximum radius of the small pulleys, giving a reduction of 1 at the end of the revolution. a complete turn. The load to be lifted, for example 50 kg, is divided into two equal efforts of 25 kg along the elements 5 and 6 and equilibrium in torque with a traction of 8 kg on the element 7. The reactions then take the values of 21 kg carried by 8 and 9. The pulleys will then turn in the clockwise direction and the traction will then increase to reach the value of the load to be lifted after a turn. The position represented by FIG. 2 is then obtained with a traction of 50 kg along the element 7, balancing the load, the reactions of the fixed reference become zero and the whole pulleys-axis is thus free to move in direct catch up with a translation of the whole mechanism.

In a particular embodiment of the invention, a device makes it possible to

returning from the direct drive position to a down position without moving the driven flexible element. During operation in action

direct, the anchorage must be disabled to allow the translation of the entire mechanism. To return to a reduced position, it is necessary to reactivate said anchoring to a new reference position. This can be achieved by any system known per se or as previously described by a

reference formed by the end of a flexible element of appropriate length fixed to a fixed part, or to the upper structure of the lifting system in the case of vertical handling. To make the internal rotation of the pulleys possible with the immobile driven flexible element, it is necessary to relieve the flexible leading element which provided the entirety of the traction to allow the anchor point to collect a growing reaction force. The mechanism will therefore move in the direction of the driving traction and the reaction force and appropriate kinematics between the pulleys and the anchor must ensure the immobility of the flexible element conducted. The anchor point must therefore move relative to the fixed reference so that the driven element remains stationary. The kinematics which ensures the relative movements is identical at each restart and can be achieved by a variable mechanical transmission using non-circular gears, non-circular pulleys, by an electronically managed system or by any other system known per se. A simple method of realization is to connect a second anchor point to the end of another flexible element which winds on the same pulley from which the driven flexible element takes place. The movement composed of the flexible element led is therefore null at any moment, because sum of two opposite movements. The only work to provide for this operation comes frictions and inertia, so remains low. It can be provided by an external source, or recovered by allowing the led element to move under a low voltage.

distance.

This operation makes perfect sense in vertical handling for a recovery

load, that is to say the restart of a winching after a stop, phase where the restart efforts are the most important because the entire chain of transmission has remained under stress. During the direct drive phase following a start, the absence of effort in the flexible reaction elements allows a possible winching system under low voltage to reposition itself to the starting position of this preparation maneuver restart. Fig.3 illustrates schematically another variant 110 of the mechanism according to the invention. It includes a pulley 112 from which an element takes place

flexible lead 114 and a pulley 116 which winds a flexible led element 118. The pulleys 112 and 116 are connected by a gear with spiral gears 120 and 122 so that there is a decreasing reduction of the effort which leads to different speeds of the flexible elements leading 114 and led 118.

The traction on the driving element 114 causes the unwinding of the latter and therefore the rotation of the pulley 112 and also of the upper spiral gear

120 to which it is coupled (secured in rotation). This causes rotation of the lower spiral gear 122 and the coupled pulley 116, and thus the winding of the driven flexible member 118.

During this phase, the driven flexible element 118 moves at a lower speed than the flexible driving element 114, which allows a smooth lifting of the load 123, requiring a tensile force proportionally

less.

In the present variant the design of the spiral gear and pulleys (1, 8/1, 5) is such that before the discontinuity of the spiral gears, a point is reached where the speed of the driving and driven elements is identical , and therefore also their pulling efforts. The pulleys and gears then stop turning. We thus reach a configuration in direct connection. In the execution of Fig.3, two types of possible anchors are illustrated. As will be understood, the anchoring is required to balance the input and output forces applied by the flexible elements. In such a configuration, the reaction is parallel to the input and output forces and in the same direction as the input whose amplitude is less (equal to the difference).

This reaction can be repeated in two different ways illustrated in FIG.

(1) Two anchor points 124 are provided in the upper part of the housing / frame 126 which supports the pulleys and gear, and are connected to cables 128 attached to a fixed reference, e.g. the lift arm (not shown). The traction force for lifting is transmitted by the lifting device via its traction cable represented by the cable 130, one end of which is connected to the driving hose 114 and the other end can be wound on a drum 132 controlled by an electric motor. .

In the initial transient phase, these cables 128 provide the reaction (materialized by the two arrows) required for balancing the traction forces while the cable 130 exerts the pulling force / lifting.

In direct drive, the mechanism 110 will rise under the force of the traction cable and the cables 128 will relax.

(2) The other possibility is simply to arrange the mechanism 110 on two shims 140 connected eg. on the ground. During the transient phase, the reaction will be provided by the two shims 140 in this case with two anchor points lower on the housing mechanism 110. Again, two arrows materialize the reaction provided by the wedges. In direct drive, the mechanism will rise by disengaging itself from this fixed reference.

It is understood that other embodiments are possible without departing from the scope of protection of the present invention.

Claims

1. Traction transmission mechanism by parallel flexible elements and moving in the same direction characterized in that it has a pulley where a flexible wound element is wound mechanically connected to a pulley from which a flexible element driving with a variable ratio of the linear velocities of the flexible elements and an anchor point to a fixed reference.

2. Mechanism according to claim 1 characterized in that it is designed so that after this initial phase with a variable ratio of the linear velocities of the flexible elements, said mechanism reaches an operating point where the pulleys no longer of rotation movement and

transmit the motion in direct drive, the ratio of the linear velocities of the flexible elements reaching the value 1.

3. Mechanism according to claim 2, characterized in that in direct drive, the flexible input and output elements are aligned.

4. Mechanism according to claim 2 or 3, characterized in that said anchoring is disengageable, providing anchoring to a fixed reference during the initial phase and allowing movement in the direction of traction in direct drive.

5. Mechanism according to any one of the preceding claims, characterized in that it comprises a frame supporting said pulleys and which is integrated in the anchor point.

6. Mechanism according to claim 1 characterized in that the ratio of the linear velocities of the flexible elements reaches at least once the value 1, with an alignment of the flexible input and output elements, for transmitting the movement in direct contact with pulleys having no more rotational movement, but the same translational movement as the flexible elements and the entire mechanism.

7. Mechanism according to any one of the preceding claims, characterized in that the input and output pulleys are integral on the same axis of rotation and that at least one of the pulleys is spiral, by its profile or by the successive thicknesses of its flexible element.

8. Mechanism according to claim 7, characterized in that one of the pulleys is doubled by an identical pulley with a corresponding parallel flexible element and that these two pulleys are placed symmetrically with respect to the third pulley.

9. Mechanism according to any one of claims 2 to 8, characterized in that the value 1 of the reduction is achieved with the 3 flexible elements in the same plane.

10. Mechanism according to any one of claims 2 to 6, characterized in that said pulleys are mechanically connected by a spiral gear.

11. Mechanism according to any one of claims 2 to 9 characterized by means for returning from the position in direct contact with a

reduced position without displacement of the flexible element led.

12. Traction system, including lifting, comprising a flexible element capable of transmitting traction to an object, the traction force is transmitted to said object via a mechanism according to any one of the preceding claims mounted on said flexible element of the system traction.