GB2171527A

GB2171527A - Weighing device

Info

Publication number: GB2171527A
Application number: GB08602805A
Authority: GB
Inventors: Philippe Blanc
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-02-18
Filing date: 1986-02-05
Publication date: 1986-08-28
Also published as: IT1187898B; GB2171527B; FR2580393A1; IT8667094A0; FR2580393B1; ES8702649A1; ES551929A0; GB8602805D0

Abstract

A weighing device suitable for objects of variable shape of which the centre of gravity cannot be located precisely, such as fruit and vegetables, comprises a series of movable carriers (10) each carrier comprising a receptacle articulated on a drawn support unit. A weighing station comprises four weighing members (P1-P4) and as each carrier is drawn over the weighing station the receptacle rests on three points (Z,Y,X1 or X2). The length of the members (P1-P4) ensures that the time which the weighing member is unloaded is approximately equal to the time of passage of each carrier over the weighing member thus allowing the measurement system to return to zero. <IMAGE>

Description

SPECIFICATION Weighing device The present invention relates to a weighing device which may form part of a system for grading by weight of objects of variable shape and of which the centre of gravity cannot be located precisely on a given axis. This invention is applicable more particularly but without being limited thereto to weighing of fruits, vegetables and similar objects.

Devices of this type which are now in use allow measurement of the couple caused by the weight of the object to be weighed and its position relative to the axis to which a force is applied to move the objects. The device which is the subject of this invention does not use this technique and it consists of measuring the real weight of the object whatever the position of the centre of gravity of the objects to be weighed.

Consequently, in one aspect this invention relates to a weighing device, notably for a system of grading by weight for objects of variable shape and of which the centre of gravity cannot be placed with precision on a given axis, notably for weighing fruit and vegetables, by measurement of the real weight, characterised in that it comprises:: (a) a plurality of movable carriers, carrying the objects to be weighed, each carrier being formed by a receptacle mounted for articulation on a movable support unit, so that it rests on three points during its passage over a plane for weighing, two of said points being common to the receptacle and the support unit; (b) means for moving the carriers so as to bring each carrier successively onto the plane of weighing, and, (c) a weighing mechanism on which each carrier successively slides and which comprises four weighing members receiving the weight of said carrier, these members all being fixed by means of a connecting plate to a force detector which analyses the force during passage of said carrier.

According to another aspect of the invention, there is provided a weighing device, suitable for measuring the actual weight of objects of different shapes such as fruit and vegetables, which comprises a plurality of movable carriers for carrying the objects to be weighed, each carrier comprising a receptacle for an object and the receptacles being articu lated to a driving system allowing each receptacle to be passed successively through a weighing station, characterised in that each carrier comprises a receptacle articulated to a support unit which is drawn to move the carrier, the receptacle resting on three points while it passes through the weighing station, two of said points being common to the receptacle and the support unit, in that the weighing station comprises four weighing members which together receive the weight of each carrier bearing an object and over which the carrier slides, the weighing members all being connected to a detector which measures the force applied to them during passage of a carrier, and in that the lengths of said weighing members in the direction of passage of the carriers is such that the time of passage of each carrier over the weighing members is approximately equal to the time during which no carrier is in contact with the weighing members to allow the detector to be reset to zero.

In one embodiment of the invention, the weighing device comprises guiding means controlling the height of the sliding parts of the carriers such that vertical dynamic forces applied by the carrier to the weighing members are minimised. The detector may comprise a strain gauge.

A weighing device according to one embodiment of the invention will be described by way of example with reference to the accompanying drawings in which: Figure 1 is a view in perspective of a carrier comprisng a receptacle and its support unit; Figure 2 is a view in lateral elevation of the carrier of Fig. 1; Figure 3 is a partial view in lateral elevation of a weighing device showing the position of the carrier of Fig. 1 during its passage over a weighing plane, and Figure 4 is a plan view of the weighing device of Fig. 3.

The weighing device shown in the drawings is made up essentially of two parts.

1. a plurality of carriers for carrying the objects to be weighed and which are displaced continuously in a horizontal path so as to pass successively over a weighing plane, and 2. a weighing mechanism effecting measurement of the actual weight of the objects during passage of each carrier over the plane of weighing.

There is first described a carrier with reference to Figs. 1 and 2.

Each carrier shown in its entirety by reference 10 comprises two distinct elements: a receptacle 12 and a support unit 14. The receptacle 12 is in the form of a plate provided with a pressed out bowl 12' for receiving the objects to be weighed, this plate comprising lugs 16, 16' and articulation points 18.

Each support unit comprises two arms 20, 20' connected by a rigid rod 22 of axis XX and by a cross-member 24. Each arm 20, 20' comprises at one of its ends a circular opening 26, 26' engaging a pulling bar of axis AA' (to simplify the drawing the pulling bar has not been shown). The receptacle 12 is mounted on the support unit 14 as shown in Fig. 2, the articulation points 18 of the receptacle resting on the rod 22 and the lugs 16, 16' engaging the cross-member 24 of the support unit. The arrangement is such that the receptacle 12 is articulated at X on the support unit 14, so that it rests at three points in the plane of weighing: one point on axis X, and two points Y and Z, so as to be able to measure the real weight of the objects positioned in the bowl 12' of the receptacle.

The weighing mechanism (Figs. 3 and 4) comprises a series of guides 28, 28', 30, 30', ensuring positioning at a given height of the sliding parts of carriers 10 when the latter are displaced continuously along arrow F, to pass successively to the weighing station. The weighing mechanism further comprises four weighing members P1, P2, and P3, P4. The weighing members P1 and P2 receive the supporting force of axis X, it being understood that the majority of the carriers only make contact on a single point of this axis X (at X, or at X2), and, at the same time, the weighing beams P3 and P4 receive the points Y and Z.

There are thus obtained two possible triangles for support X1 YZ, and X2 YZ, in the plane of weighing, which does not have any effect on the result of the weighing. In fact: The support unit 14 only transmits a quasihorizontal force, equal to the force of sliding, on advance of the carrier 10 onto the weighing system, and only a part of the weight of the support unit applies a force onto axis X, which has to be subtracted from the result of the weighing (as well as the load represented by the receptacle) in order to obtain the real weight of the objects placed on the receptacle 12. Whatever the position of the overall centre of gravity of the receptacle 10 and the object which it contains inside the support triangle X, YZ or X2 YZ, there is always established a measurement representative of the weight of the object.The arrangement of guide 28, 28' and 30, 305 is preferably such that passage of the carriers 10 over the weighing members P1 and P4 is carried out with dynamic vertical forces as low as possible.

The four members P1 to P4 are all fixed by means of a connecting plate 32, to a force detector (of the strain gauge type, for example) which analyses the force applied during passage of a carrier 10 over the plane of weighing. The lengths of the members are calculated so that the time of passage of each carrier 10 is substantially the same as that during which the weighing members do not receive any force, this latter period being used by a system for alignment onto a floating zero of the type known as "automatic return to zero". As seen in the drawing, this result is achieved by a spaced arrangement of the weighing members.

Claims

1. A weighing device, suitable for measuring the actual weight of objects of different shapes such as fruit and vegetables, which comprises a plurality of movable carriers for carrying the objects to be weighed, each carrier comprising a receptacle for an object and the receptacles being articulated to a driving system allowing each receptacle to be passed successively through a weighing station, characterised in that each carrier comprises a receptacle articulated to a support unit which is drawn to move the carrier, the receptacle resting on three points while it passes through the weighing station, two of said points being common to the receptacle and the support unit, in that the weighing station comprises four weighing members which together receive the weight of each carrier bearing an object and over which the carrier slides, the weighing members all being connected to a detector which measures the force applied to them during passage of a carrier, and in that the lengths of said weighing members in the direction of passge of the carriers is such that the time of passage carrier over the weighing members is approximately equal to the time during which no carrier is in contact with the weighing members to allow the detector to be reset to zero.

2. A weighing device according to claim 1, comprising guiding means controlling the height of the sliding parts of the carriers such that vertical dynamic forces applied by the carrier to the weighing members are minimised.

3. A weighing device according to claim 1 or 2, in which the detector comprises a strain gauge.

4. A weighing device, notably for a system of grading by weight of objects of variable shape and of which the centre of gravity cannot be located with precision along a given axis, notably for weighing fruit and vegetables, by carrying out measurement of the actual weight, which comprises a plurality of movable carriers, carrying the objects to be weighed, each carrier comprising a receptacle mounted for articulation on a driving system allowing each carrier to pass successively over a weighing plane, the device being charaterised in that each carrier (10) comprising a receptacle (12) is articulated to a traction frame (14) so as to rest at three points (X,Y,Z) during its passage over the weighing plane, two of said points (Y,Z) being common to the frame and the receptacle, in that the weighing mechanism over which each carrier slides successively comprises four weighing members (P1, P2, P3, P4) receiving the force of the weight of the carrier, the weighing members all being fixed, by means of a connecting plate (32) to a force detector (34) which analyses the force during passage of the carrier, and in that the lengths of said weighing members (P1 P2, P2, P4) are determined so that the time of passage of each carrier (10) is approximately the same as the time during which the weighing members do not receive any force, so as to allow return to zero of the measurement system.

5. A weighing device, substantially as hereinbefore described with reference to the accompanying drawings.