WO2001020211A1

WO2001020211A1 - Constant force inducing equipment

Info

Publication number: WO2001020211A1
Application number: PCT/CZ2000/000066
Authority: WO
Inventors: Petr Slabina
Original assignee: G D V, A.S.
Priority date: 1999-09-15
Filing date: 2000-09-11
Publication date: 2001-03-22
Also published as: CZ289120B6; CZ9903225A3; AU6978500A

Abstract

For suspension or support of technological devices, namely piping and parts of power and chemical equipment there is designed a constant force inducing equipment comprising elements serving for the attachment at the site, elements for suspension or support of an object, a mechanism for the conversion of the accumulated energy to constant force and a device for adjustment of the required constant force, and an energy accumulating member which comprises at least one torsion spring (1), one end of which is connected to the supporting structure while the other end engages with the mechanism for conversion of accumulated energy to a constant force, the said mechanism being furnished with a device for adjustment of the required force. The mechanism for conversion of accumulated energy to constant force comprises a cam (2) engaging with the torsion spring (1) and a flexible carrying element (3) for transmission of the constant force to the connected object, the said element (3) being attached on the cam (2). The device for adjustment of the required constant force comprises a torsion spring stressing device (5) arranged on the supporting structure and a cam setting mechanism (6).

Description

CONSTANT FORCE INDUCING EQUIPMENT

Technical Field

The invention relates to a constant force inducing equipment comprising a supporting structure, a suspension unit, an energy accumulating element, a mechanism for conversion of the accumulated energy into constant force and a device for adjustment of the required force.

Background of the invention A constant force inducing equipment is used especially for suspension or support of processing equipment, especially piping and parts of power and chemical equipment, where the position of the equipment changes due to changes of temperature, pressure and other technological factors and where it is necessary that these technology equipment remains supported by a constant force to prevent local overload and breakdown. In general there are used large devices and the applied supporting forces manifest magnitudes of several kN up to hundreds of kN. For application in a particular place the suspension must enable the adjustment of the required force in as wide range as possible. Usually the adjustment is carried out in a range of ± 30 % to the pre-set value and even more. In sleeve of the existing solutions there are even much higher peak values being achieved but the stroke of the respective equipment is reduced so much that this range is not commercially utilised. There exist a relatively large number of equipment inducing constant force. However only by a small number of them it is possible to adjust force in a larger scale, suitable for practical use. Devices and suspensions inducing constant force used so far are mostly based on accumulation of energy by coiled springs. Linear motion of a coiled spring is altered by various mechanisms so that the required resulting force is constant in the whole required stroke. Among known solutions there should be mentioned suspensions described in papers CZ inventor certificate 204 204 and CZ patent 276358, using a leverage mechanism to achieve a constant force. Another known solution is described in a patent application GB 1117- 96, using a crank arm mechanism. Both these solutions are also produced and used in various versions. Problems of the known solutions consist in a large height of respective devices, difficulties with adjustment of the required force and an uneven characteristic waveform of this force with respect to the stroke. The declared stroke is often achieved only in one point, after which the range of usable stroke decreases with further regulation of the required force. By leverage mechanisms the constant force is achieved only approximately as a resultant of forces of variously oriented levers in the mechanism and the deviation from the constant waveform often increases with the range of regulation. The crank arm mechanism used for the suspensions with constant force is on the contrary very precise and the force characteristic waveform can be perfectly constant. But it always requires a movement of a pulley or a journal along the curve of the crank arm or a cam, and the meeting surfaces must be of very high quality with regard to requirements for a long-period maintaining of the decisive characteristics. It is an object of the invention to design a constant force inducing equipment for commercial purposes complying both with a need to achieve a precise constant force and the need of adjustability of the required force in a stroke as wide as possible.

Disclosure and Object of the Invention The above object is achieved and the foregoing problems are solved by a constant force inducing equipment in accordance with the present invention comprising a supporting structure, devices for attachment of the device itself and for suspension or support of the object, an energy accumulating element, a mechanism for conversion of accumulated energy into a constant force and a device for adjustment of the required force according to the invention, comprising the energy accumulating member furnished with at least one torsion spring, one end of which is connected to the supporting structure while the other end engages with the mechanism for conversion of accumulated energy to constant force, the mechanism being furnished with a device for adjustment of the required force. Further in accordance with the present invention the mechanism for the conversion of the accumulated energy comprises a cam attached to the loose end of the torsion spring and a flexible supporting element for the transmission of the force to the object is attached to this cam. Still further in accordance with the invention the device for the adjustment of the required constant force comprises a stressing device of the torsion spring arranged on the supporting structure and a setting mechanism of the cam.

In a preferred embodiment there is provided at least one compressive element for supporting the object, the element being guided by at least one guiding element and attached to the flexible supporting element.

In another preferred embodiment the flexible supporting element is provided with a fixing component.

According to another preferred feature of the invention the supporting structure is furnished with a guiding pulley providing for positioning the carrier of the flexible supporting element into the axis of the centre of gravity of the device.

The equipment according to the invention applying a rotating motion to create a constant force have the character of a crank arm mechanism but regarding the fact the flexible lifting member is only rolled on the curved surface of the cam there is no need for the surface of the member to be of as high quality as in the sleeve of a standard crank arm mechanism and is therefore easier to be made. Embodiments as described in further presented examples of the technical solution apply a torsion spring comprising flat sheets which is easy to be made and enables modifications of shape. It also allows for a wide range of springs of a different applied force and rigidity to be manufactured from only one semifinished product, thus reducing the production costs.

Brief Description of the Drawings The invention is further illustrated by examples presented in the accompanying drawings, in which

Fig. 1 schematically illustrates constant force inducing equipment in a front sectional view, the section comprising a longitudinal axis of a torsion spring. Fig. 2 represents the equipment according to Fig. 1 in a lateral sectional view, the section comprising a plane perpendicular to the longitudinal axis of the torsion spring, with a cam in the top dead centre of the adjustment and with indicated bottom dead centre of the operation stroke of the cam, with the suspension unit of the supporting element in the bottom dead centre of the operation stroke of the suspension. Fig. 3 shows the constant force inducing equipment according to Fig. 1 in a lateral sectional view, the section comprising a plane perpendicular to the longitudinal axis of the torsion spring, with the cam in the top dead centre of the adjustment and with indicated bottom dead centre of the adjustment of the cam with the suspension unit of the supporting element in the top dead centre of the operation stroke of suspension.

Fig. 4 schematically illustrates constant force inducing equipment in an embodiment providing for a support application, the equipment being shown in a lateral sectional view, the section comprising a plane perpendicular to the longitudinal axis of the torsion spring, with the cam in the top dead centre of its adjustment an with the supporting compressive unit in the top dead centre of its operation stroke and with indicated both bottom dead centre of the operation stroke of the cam and lower operation position of the supporting compressive unit. Fig. 5 offers the equipment according Fig. 4 presented in a front partial sectional view, the section comprising the longitudinal axis of the torsion spring. Description of Preferred Embodiment

The first example of the constant force inducing equipment according to the invention, as illustrated by Figs 1 , 2 and 3, is an embodiment designed for suspension of objects. The said equipment comprises a casing 4, which together with a stressing sleeve H and a revolving sleeve 12 form a supporting structure and at the same time the outer housing of the whole device. A suspension element 43_^ allowing for attachment of the equipment in the desired place over the suspended object, is located in the upper part of the casing 4. The stressing sleeve H and the revolving sleeve 12, both of a cylindrical shape, are arranged mutually co-axially and are mounted to the casing 4, perpendicularly to its vertical axis. The stressing sleeve H is at its one end seating in the first side wall of the casing 4. The revolving sleeve 12 is fitted in the first and second bearings 41, 42 arranged in side walls of the casing 4. Through both sleeves H, 12 there runs a torsion spring 1, which is by means of blocks 3 fixed in both free ends of the sleeves H, 12. The torsion spring 1 consists of a bundle of metal sheet strips, which may be, but not necessarily, mutually interconnected. Similarly there may be used also a torsion rod or several independent or interconnected torsion rods of various diameter made of flexible materials. The torsion spring is twisted by a stressing device 5 attached to the casing 4. The stressing device 5 consists of a bolt running through a fixed grip on the casing 4, and of a lever attached rigidly to the stressing sleeve H. The stressing device 5 can also be attached directly to the torsion spring 1 , without any application of the stressing sleeve H with blocks 13. Within the casing 4 there is located a cam 2, which is connected to the revolving sleeve 12 and thus to the torsion spring 1. The cam 2 is by a pivot 21 swingingly seated in two shackles 122, which are symmetrically attached on the outer cylindrical surface of the revolving sleeve 12 .with respect to the longitudinal axis of the casing 4, Attached on the outer surface of the revolving sleeve 12, between the side walls of the casing 4, i.e. between the bearings 41,42, there is a massive nose 121 with a contact surface for the adjustment mechanism 6 of the cam 2. The cam 2 adjustment mechanism 6 is formed by a standard screw setting mechanism comprising a rod which is with one it's end swingingly connected with the cam 2 and has a nut at its other end engaging with the screw shank, the tip of which of which is leaning against the contact surface of the nose 121. Also the adjustment mechanism 6 can be arranged directly on the torsion spring 1 without application of the revolving sleeve 12 and the blocks 13.

Attached on the curved surface of the cam 2, at the end opposite the position of the pivot 21, there is one end of a flexible carrying element 3 which provides for the transmission of the force to the attached object. The flexible carrying element 3 is in the described embodiment represented by a segment chain but there can be used a rope or any other bendable and durable element, for example a belt of strong fibres, capable of transmitting the required force and at the same time wound onto the curved surface of the cam 2. The constant force inducing equipment is according to the first embodiment provided with a pulley 8 fitted inside the lower part of the casing 4 so that the lower part of the flexible carrying element 3 with a carrier 3J_. is directed substantially into a vertical axis running through the centre of gravity of the equipment. The application of the pulley 8 is preferred in both the suspension and compression versions of the said equipment. In a case of the later one, which is discussed further on, the pulley 8 can also provide for guiding of the compression element 32 in it's lower position. The flexible carrying element 3 is provided with a fixing part 7 securing the position of the carrier 3 _. in the mounting position after adjustment of the constant force. In the sleeve of the flexible carrying element 3 formed by a segment chain, individual segments serve also for the fixation. In the discussed embodiment there is used a piece with coaxial pivots. The piece leans with it's side surface parallel to the plane running through the longitudinal axis of the pivots against an edge of the casing 4 or other part of the casing 4 at the passage of the chain. The fixing of the carrying element 3 can be also provided for by other means, for example by a clamp, wedge etc. The second embodiment of the constant force inducing equipment, as presented in Figs 4 and 5, is designed to support an object by a constant force. Such equipment consists mostly of parts identical to those used in the embodiment for suspension of objects. The casing 4 has a different shape. Instead of the suspension element 43 the casing 4 is provided with openings for bolts or with flanges for placing and securing the device in the place under a supported object. The discussed embodiment of the constant force inducing equipment for supporting of objects is provided with two compression elements 32 arranged co-axially in the casing 4 and mutually crosswise interconnected so that there is enough space between them for movement of the cam 2. The compression elements 32 are supported in vertical position within the axis of the gravity centre of the whole device by means of a guiding 321. The compression elements 32 are connected at the end opposite to the point of fixing to the flexible lifting element by a supporting board 322 with an opening and a screw thread in it. This supporting board 322 serves for attachment of supported objects. The flexible carrying element 3 in this supporting embodiment is shorter than by the suspension embodiment. Fixing of the supporting constant force inducing equipment in the mounting position is realised by blocking of the movement of the compression element 32 towards the casing 4. The function of the device according to the technical solution is as follows. An object which is to be suspended by a constant force along the whole trajectory of expected dilatation is by means of the carrier 3J. and the carrying element 3 attached to the cam 2, which by means of the revolving sleeve 12 is twisting the torsion spring 1. The constant force of the suspension along the whole required trajectory is achieved due to a shape of the cam 2. By setting the cam 2 through the adjustment mechanism 6 the length of an arm of the applied force is changed so that the proportion of the torsion spring 1 momentum to the applied force arm is constant. By adjustment of the desired constant force the momentum of the spring 1 and a position of the cam 2 are set so that the trajectory of the flexible element 3 and the waveform of the torsion spring 1 momentum provides for the constant force. The adjustment procedure is carried out in two steps. Using the stressing device 5 there is set the initial momentum of the torsion spring 1. By means of the adjusting mechanism 6 the position of the cam 2 is set so that the resulting trajectory of the flexible element 3 creates constant force from the torsion spring 1 momentum waveform. That means that for a smaller force the cam 2 is tilted back, its distance from the nose 121 being increased, so that the arm of induced force grows fast during the twisting of the torsion spring 1. For a larger force the cam 2 is drawn closer to the nose 121 to keep the force on a constant level. The desired position of the carrying element 31 for the mounting can be for example achieved by blocking the flexible element 3 by means of the fixing part 7.

Industrial application

The constant force inducing equipment is designed for suspension or support of technological devices, namely piping and parts of power and chemical equipment where due to changes in temperature, pressure and other technology factors their position changes and to prevent local overload and breakdown the equipment must be supported by a constant force.

Claims

1. A constant force inducing equipment comprising elements serving for the attachment at the site, elements for suspension or support of an object, a member accumulating energy, a mechanism for the conversion of the accumulated energy to constant force and a device for adjustment of the required constant force, characterised in, that the energy accumulating member comprises at least one torsion spring (1), one end of which is connected to the supporting structure while the other end engages with the mechanism for conversion of accumulated energy to a constant force, the said mechanism being furnished with a device for adjustment of the required force.

2. The equipment according to claim 1 , characterised in, that the mechanism for conversion of accumulated energy to constant force comprises a cam (2) engaging with the torsion spring (1) and a flexible carrying element (3) for transmission of the constant force to the connected object, the said element (3) being attached on the cam (2).

3. The equipment according to claim 1 , characterised in, that the device for adjustment of the required constant force comprises a torsion spring stressing device (5) arranged on the supporting structure and a cam setting mechanism (6).

4. The equipment according to claim 2, characterised in, that at least one compression element (32) for supporting the object, the element being guided by at least one guiding (321), is attached to the flexible carrying element (3).

5. The device according to the claim 2, characterised in, that the flexible lifting element (3) is provided with a fixing component (7).

6. The equipment according to claim 2, characterised in, that a part of the flexible lifting element (3) with a carrier (31) is guided in a substantially vertical plane running through the centre of gravity of the device by means of a guiding pulley (8) arranged at the bottom of the supporting structure.

5 drawings