FR2956981A1 - Individual tensiometer for measuring tension of racket string, has flexible strip deformable by rotation of base body around axis transverse to string and parallel to median plane, and measuring unit measuring flexion deformation of strip - Google Patents

Abstract

The tensiometer (1) has a stressing component (2) with support elements e.g. studs or fingers, positioned on two sides of a racket string (9). An elongated deformable element i.e. flexible strip (3), connects an ellipsoidal shaped base body (10) to the component. The strip is deformable by rotation of the body around an axis transverse to the string and parallel to a median plane passing between the support elements, at an overlapping state of the support elements on the string. A measuring unit i.e. extensometer (4), measures flexion deformation of the strip. An independent claim is also included for a method for determining tension of a racket string.

Description

The present invention generally relates to tension measuring apparatus for rope type elongate member.

The invention more particularly relates to an individual tensiometer for measuring the tension of a racket rope, said tensiometer comprising: - a basic body, - a member for stressing the rope by deformation of said rope, said biasing member comprising at least two support elements spaced apart from one another, such as studs or fingers, positionable on either side of an individual rope, - a deformable element connecting the base body to the biasing member of the rope, said deformable element being, in the state straddling the rope of the two support elements of said biasing member, deformable by rotation of said base body about an axis transverse to the rope and parallel to the median plane passing between said support members straddling the rope. The invention also relates to a method of measuring rope tension with such a tensiometer.

It is known from the state of the art and in particular from US 5, 481, 926 a voltage measuring device as described above. In this document, the base body is connected by a helical spring to the stress member of the rope. To measure the tension of the rope, the base body is rotated until a reference portion of the biasing member comes to the right of the rope. The tension of the rope is then determined from the relative angle of rotation obtained between the biasing member and the base body following the rotation of the base body.

Said relative angle corresponds to an elongation of the helical spring biased in tension. The more the rope is tensioned, the greater the relative angle between the base body and the biasing member will be significant and the spring will be stressed in traction. Conversely, the more the rope is relaxed, the less the relative angle will be important and less the spring will be stressed in traction. However, it is observed that because of the connection between the base body and the biasing member by an element which elongates by traction, the measurement of the relative angle is not very precise. Indeed, the capacity of spring elongation may vary over time, the coil spring is a piece that wears and whose elastic behavior is rapidly degraded. In addition, according to this document US 5, 481, 926, the determination of the tension of a rope is made from the reading of graduations on a dial and corresponding to different values of relative angle between base body and solicitation organ, which is very uncomfortable to use. Note also that to allow said spring to be biased in tension, it is off-center of the axis of rotation of the base body. Thus, the tensiometer disclosed in US 5, 481, 926 operates in only one direction of rotation of the base body corresponding to the direction in which the spring can be elongated. Such a solution thus poses problems for left-handed people when the tensiometer is designed for right-handed people and vice versa.

Finally, the elongation properties of the helical spring, which acts as a connection between the base body and the biasing member, are very sensitive to the different racket cord diameters, which necessitates predicting, as is the case in US 5, 481, 92, an additional system of specific adjustment of the tensiometer as a function of the diameter of the rope of which it is desired to measure the tension. The design and use of the tensiometer according to US 5, 481, 92 are all the more complex. It is an object of the present invention to provide a blood pressure monitor which is easily manipulable for both left-handed and right-handed users.

Another object of the present invention is to provide a simplified design sphygmomanometer while being stronger and offering a more reliable and accurate voltage measurement. Another object of the present invention is to provide a tensiometer for which the user can easily and quickly determine the tension of a rope.

For this purpose, the subject of the invention is an individual tensiometer for measuring the tension of a racket rope, said tensiometer comprising: a basic body; a member for biasing the rope by deformation of said rope; said biasing member comprising at least two support elements spaced from each other, such as studs or fingers, positionable on either side of an individual rope, - a deformable element connecting the base body the straining member of the rope, said deformable element being, in the state straddling the rope of the two support elements of said biasing member, deformable by rotation of said base body about a transverse axis to the rope and parallel to the median plane passing between said support elements straddling the rope, characterized in that said deformable element is a flexible element, and in that said tensiometer is equipped with means for measuring the deformatio n by flexing said flexible member. For a given angle of rotation of the base body from an applied initial position of the two support elements against the rope, the bending deformation of the flexible element is a function of the internal or initial tension of the rope. that is, the tension of the rope in the absence of stress on it. Thus, the measurement of the bending of the flexible element which results from the rotation of the base body makes it possible to determine the tension of the rope.

The tensiometer according to the invention makes it possible to solve the problem of the direction of rotation of the base body posed by the tensiometers known from the state of the art, by connecting the base body to the biasing member by a flexible element such as that a flexible blade. Indeed, the relative rotation between the basic body and the biasing member, in one direction and in the other, causes a flexion of the flexible element which can be detected in both directions, for example with the same or the same set of onboard stress gauge (s) on the blade.

The use of a flexible element to connect the base body to the biasing member, also improves the measurement accuracy of the tension of the rope and facilitate the manipulation of the tensiometer in comparison with the solutions of the state of the art which determines the tension of a rope from the elongation of a helical spring.

In fact, over time, the bending behavior of a flexible element is stable and the risk of degradation of the bending properties of said element is very small compared to the risk of degradation of the elongation properties of a helical spring. Bending of the flexible element is also a reliably and accurately measurable parameter in both a bending direction and a reverse direction.

It is further observed that the measurement of tension of a rope by exercising a torque on the rope, and then measuring the deformation of a flexible element connected to the rope, is accurate and reliable. Finally, contrary to the use of an elongation-deformable element, as is the case with the helical spring of US Pat. No. 5,481,926, the bending deformation of the flexible element is not very sensitive to the various diameters of racket rope, which allows to exempt additional system of specific adjustment of the tensiometer according to the diameter of the cable. The tensiometer according to the invention can therefore be used to determine the tension of rackets of different diameters without having to make particular adjustments.

Advantageously, said means for measuring the bending deformation are carried by said flexible element. According to an advantageous characteristic of the invention, said means for measuring the bending deformation comprise at least one strain gage. Advantageously, the tensiometer comprises means for calculating the tension of the rope from the measurement of the flexion of the flexible element.

The use of at least one strain gauge makes it possible to provide an electrical signal representative of the bending of the flexible element that can be processed by electrical and / or computer calculation means to determine the corresponding tension of the rope. In particular, it is possible to filter Io and / or to amplify the signal at the output of the strain gauge or gauges.

According to an advantageous characteristic of the invention, the base body is an annular body, for example of ellipsoidal shape.

According to a preferred embodiment of the invention, the flexible element being an elongated element extending inside the space delimited by said annular base body, the opposite ends of the flexible element are connected to two distinct points of the annular base body, preferably at two diametrically opposite points. The biasing member is attached to the flexible member 20 between and spaced from both ends of the flexible member, preferably in the middle region of the length of said flexible member.

According to an advantageous characteristic of the invention, the flexible element being an elongated element having a longitudinal axis orthogonal to its axis of flexion, the flexural measuring means are located at least partly between the biasing member and the end or one end of the flexible element connected (s) to said base body, preferably in the middle of the length between the biasing member and said end of said flexible member.

According to an advantageous characteristic of the invention, the flexible element being an elongated element, the longitudinal axis of the flexible element is substantially coplanar with the axis of rotation of the base body defined by the axis which is included in FIG. the median plane passing between said support members intended to overlap the rope and which is perpendicular to the axis of the rope passage delimited between the two support elements.

In other words, the flexible element formed for example by a beam or flexible blade is substantially centered on the axis of rotation of the base body of the tensiometer, which allows to have a substantially identical behavior in flexion of the flexible element in meaning and in the other, and thus to determine reliably and quickly the tension of a rope that is deformed in one direction or the other. Such an arrangement of the flexible element with respect to the axis of rotation of the base body also simplifies the design and manufacture of the tensiometer while providing an effective measure of the tension of the rope from flexion of the body. flexible member in one or other bending direction, corresponding to a rotation of the base body in one direction or the other depending on whether the user is right-handed or left-handed.

The invention also relates to a method for determining the tension of a racket rope, using a tensiometer as described above, said method comprising the following steps: positioning the tensiometer biasing member astride by its two support elements on an individual rope, - turn the base body of the tensiometer until a predefined orientation of the base body with respect to the rope, in which the two support elements of the biasing member exert a torque on the rope, - measuring the bending deformation of the flexible element which connects the biasing member to the base body, - calculating, from the measured bending value, the tension of the rope.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which: FIG. 1 is a perspective view of the tensiometer according to the invention; FIG. 1A is a view from above of the tensiometer of FIG. 1; FIG. 1B is a side view of the tensiometer of FIG. 1; - Figure 2 is a top view of the tensiometer according to the invention in the state straddling a rope, before deformation of said rope; FIG. 2A is a side view of the tensiometer of FIG. 2, in a state that straddles the rope, before deformation of said rope; FIG. 3 is a view from above of the tensiometer according to the invention, in the state straddling a rope and in the rotated state of the basic body until obtaining the desired orientation of said body with respect to the rope. ; FIG. 3A is a side view of the tensiometer of FIG. 3 in engagement with the rope.

With reference to the figures and as recalled above, the invention relates to an individual blood pressure meter 1 for measuring the tension of a racket rope 9. Said rope whose voltage is to be measured is recessed at or near its ends on the racket frame (not shown).

Said tensiometer 1 comprises a base body 10, a biasing member 2 of the rope 9 by deformation of said rope and a deformable element 3 connecting the base body 10 to the biasing member 2 of the rope. Said biasing member 2 comprises at least two support elements 21, 22 spaced apart from one another, such as studs or fingers, positionable on either side of the rope 9. Said deformable element 3 is, in the state straddling the rope 9 of the two support elements 21, 22, deformable by rotation of said base body 10 about a transverse axis ROT1 to the rope and parallel to the median plane passing between said elements of support 21, 22 straddling the rope 9. In particular, said axis of rotation ROT1 passes through the median plane which separates the two support elements 21, 22 and is orthogonal to the axis of the rope passage delimited between the two elements. In a manner characteristic of the invention, said deformable element 3 is a flexible element, and said tensiometer 1 is equipped with means 4 for measuring the bending deformation of said flexible element. In the example illustrated in the figures, said flexible element 3 is a flexible blade. The average plane of the flexible blade 3, in the unsolicited state, is parallel to the axis of rotation ROT1 of the basic body. As detailed below, said measuring means 4 are preferably formed by at least one strain gauge.

Said base body of said tensiometer is intended to be rotated about said axis of rotation ROT1 until said base body has a given predefined orientation with respect to the rope, said biasing orientation, for which the rope is biased by deformation . Thus, to measure the tension of the racket rope, the bending of the flexible element is measured after the base body 10 has rotated about the axis of rotation ROT1 until the desired orientation of said base body is obtained. 10 with respect to the rope 9.

Said biasing orientation may correspond to the superposition of the straight line passing through two distinct points of the base body 10, with the straight line passing through the rope 9. In the example illustrated in the figures, said points of the base body 10 serving as the reference, for alignment with the rope 9, are the two opposite connection zones of the flexible element 3 to the base body 10. Said biasing orientation can also correspond to a given angle of rotation of the base body relative to a configuration in support of the support elements 21, 22 against the rope 9.

The rotation of the base body 10 about an axis ROT1 orthogonal to the rope 9 and parallel to the median plane passing between the support elements 21, 22 of the biasing member, generates, on the one hand, a torque the biasing member on the rope by support in the opposite direction of the two support elements 21, 22 on the rope, and, on the other hand, a bending deformation of the flexible element 3 to follow the rotation of the body base 10 while the biasing member 2 is engaged with the rope. During the rotation of the base body 10, the two bearing elements 21, 22 exert a torque on the rope 9 which more or less deforms the rope according to its initial tension, that is to say in the absence of solicitation. The flexure of the flexible member 3 depending on the deformation of the rope 9, that is to say the capacity of the biasing member 2 to follow the rotational movement of the base body 10, the measurement of the flexion of the flexible element 3 makes it possible to determine the initial tension of the rope 9.

Indeed, the less the rope 9 is stretched initially, the more it will tend to deform easily under the effect of the torque applied by the biasing member 2 when the base body 10 is rotated in the stress configuration of the rope 9. The flexible element 3 which connects the base body 10 to the biasing member 2 in engagement with the rope 9 will all the less need to bend to follow the rotational movement of the base body 10.

Conversely, the longer the rope 9 is stretched initially, the more it will withstand the torque applied by the biasing member 2 when the base body 10 is rotated to reach the desired orientation with respect to the rope 9. It results that the flexible element 3, which connects the base body 10 to the biasing member 2 in engagement with the rope 9, will all the more flex around its axis of flexion parallel to the axis of rotation ROT1, to follow the rotation movement of the base body 10.

The axis of rotation ROT1 is orthogonal to the plane of the strings which makes it possible to easily apply a torque via the biasing member 2 to a rope 9 inside the racket frame with great freedom and ease of manipulation of the sphygmomanometer . As illustrated in the figures, the flexible blade 3 is then arranged so that its bending axis is parallel to the axis of rotation ROT1, that is to say orthogonal to the mean plane of the rope.

The choice of such an axis of rotation ROT1 of the base body, orthogonal to the plane of the ropes, for deforming the rope, makes it possible to design the biasing member in the form of two studs, of generally cylindrical shape, spaced apart. one of the other and connected by a support or platinum 20, it is sufficient to position 2956981 i0 directly astride a rope. The pads 21, 22 project from the plate 20 being spaced apart from each other in a direction orthogonal to their projection direction so as to be mounted astride a rope. In the state positioned astride the biasing member on the rope, the plate 20 which connects the two studs extends on one side of the frame of the racket, which facilitates the positioning of the two studs 21, 22 on both sides of the rope 9 and thus the manipulation of the tensiometer. In particular, the user can easily rotate the base body along the desired axis without being bothered by the ropes. The two supporting elements 21, 22 of the biasing member 2 extend substantially parallel to each other and orthogonally to the mean plane of said base body 10 or to the middle plane of the plate 20.

In the example illustrated in the figures, said bending measurement means 4 are positioned on one face of the flexible blade 3. In a variant, said bending measurement means can be distributed on each of the faces of the flexible blade 3.

In particular, said measuring means 4 are positioned in the median zone of the portion of the flexible blade 3 situated between the biasing member 2 and one of the three ends 3A, 3B of the blade 3 connected to the body of the blade 3. base 10 as detailed below. Indeed, it is in this area that bending deformation is the most important. In a variant, said measuring means 4 can be distributed over each of the two portions of the flexible blade 3 defined between the biasing member 2 and a flexible blade end connected to the base body 10.

Said bending measurement means 4 preferably comprise at least one strain gauge 4, also called strain gauge, configured to measure the bending deformation of said flexible blade. Preferably, said measuring means 4 are formed of several strain gages. The or each strain gauge forms a means of converting the bending deformation undergone by the blade into electrical signals.

The tensiometer comprises electronic and computer means (not shown), such as a microprocessor, for calculating the tension of the rope 9 from the measurement of the flexion of the flexible element 3. The term "tension" means the initial tension or at rest of the rope, that is to say in the unsolicited state of the rope by the biasing member.

In particular, the or each gauge 4 transmits to the computing means in the form of an electrical signal a variable impedance (or resistance) value as a function of the bending deformation of the blade. Said calculation means can be positioned in or on the basic body. The computer and electronic computing means determine from the bending of the blade, using a calculation function, a correspondence table, or abacuses, the corresponding tension of the rope, which allows to directly signify to the user the determined voltage, for example by displaying the determined value on a screen fitted to the blood pressure monitor, and not by reading a graduation of a dial, which is uncomfortable, as it is the case with tensiometers known from the state of the art. The base body 10 is an annular body, for example of ellipsoidal shape. In the example illustrated in the figures, the axis of rotation ROT1 of the base body is orthogonal to the mean plane of said basic body.

The flexible member 3 extends within the space defined by said annular base body. The opposite ends 3A, 3B of the flexible element 3 are connected to two distinct points of the annular base body 10, preferably at two diametrically opposite points. The biasing member 2 is fixed to the flexible member 3 between and spaced apart from the two ends 3A, 3B of the flexible member 3, preferably in the middle region of the length of said flexible member 3. The flexible member 3 has a longitudinal axis A3 orthogonal to its axis of bending. Said measuring means 4 are located, in the example illustrated in the figures, between the biasing member 2 and the one 3B of the ends 3A, 3B of the flexible element connected to said base body, preferably in the middle of the length between the biasing member 2 and said end 3B of said flexible member 3.

The flexible element 3 carries the biasing member 2 between its two ends 3A, 3B, preferably at half the length of said flexible element 3.

The opposite ends of the flexible member 3 are connected to the base body 10 at opposite points or areas of the base body. At least one, preferably each, end 3A, 3B of the flexible elongated element, spaced apart from the biasing member 2, is coupled to the base body 10 so as, on the one hand, to leave said flexible element 3 a axial clearance with respect to said base body 10 (that is to say along the longitudinal axis of the flexible element in the undeflected state of said element) to absorb the variations in distance between the two ends 3A, 3B of the flexible element 3 during its bending, and, secondly, to prevent the displacement of said at least one end 3A, 3B in a direction transverse to the axis of said flexible element 3. Said direction transverse to the axis is taken in the unsolicited state of said flexible member 3, to allow said member to flex when the base body 10 is turned by the operator about said axis of rotation ROT1.

Thus, it can be provided that one of the ends 3A, 3B or each end 3A, 3B (as shown in the figures) of the flexible element is housed in a slot, formed in the base body, the sides of which sandwich the lateral parts of the end portion 3A, 3B of the flexible element housed in said slot, while said end portion 3A, 3B of the flexible element is able to sink more or less inside of the slot according to its bending deformation. The longitudinal axis A3 of the flexible blade 3 is substantially coplanar with the axis of rotation ROT1 of the base body 10 defined by the axis which is included in the median plane passing between said bearing elements 21, 22 intended to overlap the rope 9 and which is perpendicular to the axis of the rope passage defined between the two bearing elements 21, 22. The longitudinal axis A3 of the blade extends substantially orthogonal to the axis of rotation ROT1 of the body of 2. In the example illustrated in the figures, the average plane of the blade is substantially coincident with the mean plane which passes through the longitudinal axes of the two studs 21, 22.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

Claims (10)

REVENDICATIONS1. An individual sphygmomanometer (1) for measuring the tension of a racket rope (9), said tensiometer (1) comprising: s - a base body (10), - a straining member (2) of the rope (9) ) by deformation of said rope, said biasing member (2) comprising at least two support elements (21, 22) spaced apart from each other, such as studs or fingers, positionable on either side of an individual rope (9), - a deformable element (3) connecting the base body (10) to the straining member (2) of the rope, said deformable element (3) being, in the state to be riding on the rope (9) of the two support elements of said biasing member (2), deformable by rotation of said base body (10) about a transverse axis (ROT1) to the rope and parallel to the median plane passing through between said supporting elements (21, 22) straddling the rope (9), characterized in that said deformable element (3) is a flexible element, and in that said tensiom be (1) is equipped with measuring means (4) of the bending deformation of said flexible member. 20 2. A blood pressure monitor according to claim 1, characterized in that said flexible element (3) has the shape of a flexible blade. 3. Tensiometer according to one of the preceding claims, characterized in that said means (4) for measuring the bending deformation are carried by said flexible element (3). 4. Tensiometer according to one of the preceding claims, characterized in that said means (4) for measuring the bending deformation comprise at least one strain gauge (4). 5. Tensiometer according to one of the preceding claims, characterized in that it comprises means for calculating the tension of the rope (9) from the measurement of the bending of the flexible element (3). 6. Tensiometer according to one of the preceding claims, characterized in that the base body (10) is an annular body, for example of ellipsoidal shape. A sphygmomanometer according to claim 6, characterized in that the flexible element being an elongated element extending within the space defined by said annular base body (10), the opposite ends (3A, 3B ) of the flexible element (3) are connected to two distinct points of the annular base body (10), preferably at two diametrically opposite points, the biasing member (2) being fixed on the flexible element (3) between and spaced apart from both ends (3A, 3B) of the flexible member (3), preferably in the middle region of the length of said flexible member (3). 8. Tensiometer according to one of the preceding claims, characterized in that, the flexible element (3) being an elongated element having a longitudinal axis (A3) orthogonal to its axis of bending, the measuring means (4) 20 are at least partially between the biasing member (2) and the end or one end (3A, 3B) of the flexible member connected to said base body, preferably in the middle of the length between the biasing member (2) and said end (3B) of said flexible member (3). 25 Sphygmomanometer according to one of the preceding claims, characterized in that, the flexible element (3) being an elongated element, the longitudinal axis of the flexible element (3) is substantially coplanar with the axis of rotation ( ROT1) of the base body (10) defined by the axis which lies in the median plane passing between said support members (21, 22) for overlapping the rope (9) and which is perpendicular to the axis the rope passage delimited between the two support elements (21, 22). 10. A method for determining the tension of a racket rope (9), with the aid of a tensiometer (1) according to one of the preceding claims, characterized in that said method comprises the following steps: - positioning the urging member (2) of the horse-drawn sphygmomanometer by its two supporting elements (21, 22) on an individual rope (9), - rotating the basic body (10) of the blood pressure device to obtain a predefined orientation of the base body (10) with respect to the rope (9), in which the two supporting elements (21, 22) of the biasing member exert a torque on the rope (9), - measuring the deformation by bending the flexible element (3) which connects the biasing member (2) to the base body (10); - calculating, from the measured bending value, the tension of the rope (9).