A DEVICE FOR TRANSFERRING FORCES TO BE MEASURED TO AN INSTRUMENT FOR MEASURING FORCES

Abstract: The invention is directed to a device for transferring forces to be measured to an instrument for measuring forces, comprising a support for receiving forces and acting upon said instrument, said support being movable essential­ ly in the direction of said forces and comprising a lever assembly being arranged between said support and a fixed frame or wall. The lever assembly comprises at least two levers of essentially the same length, having pivots fixed on one hand with one end at the wall or fixed plane and on the other hand at a support for the forces to be measured. The projections of the axis of the at least two levers in a plane perpendicular to the axis of said levers and parallel to the direction of the movement of said support are spaced apart from each other in the direction of said movement.

Description: A device for transferring forces to be measured to an instrument for measuring forces The invention is directed to a device for transferring forces to be measured to an instrument for measuring forces, comprising a support for receiving forces and acting upon said instrument, said support being movable essentially in the direction of said forces, and comprising a lever assembly being arranged between said support and a.flxed frame or wall said lever assembly having at least one pivot for enabling said movement. There are any devices of the described type having elements like pivoting points which as a result of increasing friction in the bearings or faults, for instance because of collecting dust in the lever system, can lead to decreasing accuracy, so that the indicated values are fault values. The task of the invention is to create a device of the mentioned type by which the mentioned disadvantages will be prevented and which allows a measurement independent of the location of the point of force at the support. The solution of the invention is characterized in that the lever assembly comprises at least two levers of essentially the same length, that the levers have pivots fixed on one hand with one end at the wall or a fixed plain and on the other hand at the support for the forces to be measured and that the projections of the axis of the at least two levers in a plain perpendicular to the axis of that levers and parallel to the direction of the movement of that support are spaced appart from each other in the direction of that movement. This arrangement allows the measurement of the forces acting on the support at different locations. In the following subclaims there are disclosed further ad ntageous features of the device of the mainclaim. The present invention is shown on the accompanying drawings and disclosed in the description: Figure 1 shows schematically an embodyment of the inventive device, Figure 2 shows a device according figure 1 ore in detail. The device for transferring forces t¸ be measured comprises two parallel levers 1, one of the end points of which being fixed to the main frame 2 and the other end point being fixed to a support 4. On the support 4 the forces to be measured or an object (P1,P2) which is to be measured can be fixed at any suitable point or location. The support 4 is collected to a load cell 6 or another conventional device for measurement of the forces which carl convert the forces into an electric, pneumatic of mechanic signal. The searched force in figure 1 has the reference L. It has to be pointed out that neither the location of that support nor the position where the forces to be measured are acting nor the position where the load cells or a similar instrument is placed have any nfluerlee on the measured forces. Further moze all forces in the direction perpendicular to the proposed direction of the forces in question respectively forces in the direction parallel to the lever bars, like the forces N have no influence on the measured forces. Also the change of the force R on the place of the load cell of other instruments for measurement of forces is equal to the sum of changes of the forces (P1,P2) acting on the support in the direction perpendicular to the direction of the lever bars. In figure 2 there is shown a special design of the inventive device, wherein the lever bars 1 are designed as plate springs. The instrument for measurement of forces is a conventional load cell 6. The support 4 is connected to the plate springs 1 and has a bar on which all forces are acting, which bar on the other hand acts itself on the load cell. A special characteristic of this construction is that tne plate springs 1 made from metal or other elastic material have practically no damping hysteresis, which means that by any change of forces the measurement of the whole system, as a result of an elastic deformation of the instrument for measurement always returns to its initial position and thus there will not occur any deviation regarding the measured forces. This displacement of the whole system is very small and depends on the load cell 6, it has the magnitude of about 0,1 mm. Due to this small displacement the deformation of the plate springs also is very small with the result, that the hysteresis also is very small and therefore negligible. For the compensation of the tare weight of the lever system or any other forces which belong to the tara weight there is provided a device consisting of a coil spring 5 which preferably has a very small spring constant by reinforcement of this coil spring each tare weight can be comparsated wit bout decreasing the sensitivity of the load cell. Aprotection device against the overload of the load cell or the other measurement device is built up by reinforce piston. 7 being positioned in a linear bearing 11 and being reinforced by a coil spring 9. The movement ol' this piston 7 downwards is limited by a stop piece 8. The piston being relriforced by said coil spring 9 so that for the force below maximum of said forces to be measured the protection device is non elastic and for forces above that maximum the coil spring 9 deforms, so that the measuring arm touchs the tup piece 8 so tIlut the forces acting on the load cell 6 ale limited oiily by the deformation force of the coil spring 9 according to the distance between the support ard thC stop piece. Said coil spring 9 has to be dimensioned in such a way that if the support arm moves over the distance 10 until it touchs the stop piece 8 the forces acting on the load cell stay within allowable values. rii is possible by such a choice of the spring that the Increase of the forces corresponding with the deformation distance 10 is not greater than 10 to 20 % of the reinforced force which approximately is 110 % to 120 % of the maxima weighing force.

Claims: P A r E N T C L A I M S 1) A device for transferring forces to be measured to an instrument for measuring forces, comprising a support for receiving forces and acting upon said instrument said support being movable essentially in the direction of said forces, and comprising a lever assembly being arranged between said support ad a fixed frame or wall saic lever assembly having at least one pivot for en abling said movement, c h a r a c t e r i z e d in that the lover assembly comprises at least two levers of essentially the same leiigbh, that the levers have pivots fixed on one hand with one end at the wall cr fixed plane and on the other hand at a support for the forces to be measured and that the projections of tic axis of the at least two levers in a plane perpendicular to the axis of said levers and parallel to the direction of the movement of said support are spaced apart from each other in the direction of said movement. ') Device according to claim 1 c h a r a c t U r i z e d iJI that the pivots at tare end of the levers form a parllelogramm. 3) Device according to claim 1 or 2, c h a r a c t e r i z e d in that the support comprises arms extending in the plane parallel to the axis of the lever and parallel to the direction of the movement of the support. 4) Device according to claim 3, c h a r a c t e r i z e d in that said support arms having volontary direction within said plane. 5) Device according to claim 3 or 4, c h a r a c t e r i z e d in that said forces to be measured can be fIxed at volontary points of said support arms, whereby the component of said forces being perpen dicular to the axis of the levers will be measured. 6} Device according to one of the claims 1 - 5, c h a r a c t e r i z e d in that the instrument for measuring is positioned such that the direction of the measurement is perpendicular to the direction of the axis of the levers. 7o device according to at least orie of the claims 1 - 6, c h a r a c t e r i z e d in that the lever bars are plate springs. 6) Device according to at least one of the claims 1 - 7, c h a r a c t e r i z e d in that the lever bars are formed by two pivoting points connected within a non-elastic lever. 9) Device according to at least one of the claims 1 - 8, c h a r a c t e r i z e d in that the pivots are built up by knit ede in the pivoting point. 5 evice according to at least one of the claims 1 - 8, c h r a c t e r 1 z e d in that these are provided means for protection against overload of the instrument for measurement of the forces, said device being a linear bearing positioned piston which is reinforced by a spring which spring reinforcement is such that the piston moves only when the force to be measured gets bigger than nominal forces of the instrument for measurement of forces, whereby the movement of said support of said device is limited by a stop piece in such a way that the force on the instrument equal to the reinforcement and deflection of the spring staying belong the maximal allowed forces on the instrument. 11) Device according to at least one of the claims 1 - 10, c h a r a c t e r i z e d in that the tare weight is compensated by the force of a reinforced spring. 1') Device according to at least one of the claims l - 11, c h a r a c t e r i z e d in that the support is a silo.

Inventors: IVAN A.S.Z. PESCHL
Applicants: IVAN A.S.Z. PESCHL
Application year: 1985
Main classification: G01G21
IPC codes: G01G3, G01G21