ARRANGEMENT IN A VEHICLE OR THE LIKE FOR WEIGHING THE LOADING WEIGHT

Abstract: The invention relates to an arrangement for the measuring of the loading weight of a vehicle by means of sensor devices which are installed between the frame structure (22) and the wheel-and-axle sets (19, 29) in such a manner that the principal cylinder part (25) belonging to the sensor device (7) is connected to one of them and the principal piston part (26) respectively to the other. Between them, inside the principal cylinder part, there is the measuring-fluid space (28). The output signals of the sensor devices (7) are coupled, at least in pairs, in parallel in order that the loading weight is obtained via means or via a sum, the output signals being based on the change of pressure in the measuring-fluid spaces of the sensor devices as the load increases. The measuring-fluid spaces (28) in the sensor devices (7) are formed separately for each measuring round by pressing the definer pistons (23) inside the principal cylinder parts, by means of the pressure of the measuring fluid, from the resting position into the measuring position, in which they delimit the measuring-fluid volume. The measuring-fluid volumes or volume are/is locked at this pressure and the indicator devices are zeroed, whereafter the loaded weight is detected from the pressure increase appearing as a result of it in this fixed fluid volume or in each fixed fluid volume.

Description: Arrangement in a vehicle or the like for weighing the loading weight The present invention relates to an arrangement for measur¬ ing the loading weight of a vehicle or a corresponding unit by using sensor devices installed in the vehicle between the frame structure and the wheel-and-axle sets or corre¬ sponding devices in such a manner that the principal cylin¬ der part belonging to the sensor device is connected to one of them and the principal piston part to the other, there being between them inside the principal cylinder part a measuring-fluid space, the output signals of the sensor devices being coupled at least- in pairs in parallel in order to obtain the loading weight via means or via a sum, and the said output signals being based on a change of pressure in the measuring-fluid spaces of the sensor devices. There are known numerous scales on top of which a vehicle or a vehicle combination is driven for weighing the total weight of the load. Because of their size, such scales must, however, be. installed fixedly, in which case their usability is highly limited. In general such scales are in use only in rather large industrial plants or the like. From FI Patent Application 1497/73 there is known a method for adjusting the bogie wheels of a vehicle. The system is based on the adjustment of the bogie wheels of a vehicle by means of a bogie-lifting apparatus on the basis of the weight of the vehicle and the load in it. The said weights are detected by means of a lever turning along with the load of a spring placed between the spring assembly and the fixed axle of the vehicle. The purpose is to detect the load limit at which one of the bogie axles can be taken in or out of use. GB Patent 1 151 396 describes automatic load detection for a vehicle axle. In the system, the pressure acting on the hydraulic system of the bogie-lifting device is detected, and at certain limit values the pressure either raises or lowers the bogie axle. In addition to this, a large number of arrangements have been disclosed the purpose of which is to weight the weight of the load in a vehicle, a trailer, a railway wagon, or the like. What all of these arrangements have in common is that they are based on measuring the yielding allowed by the actual spring suspension of the vehicle when, for exam¬ ple, a load is brought on top of the frame of the vehicle. This indication may be a fully mechanical indicator of the distance between the frame and the wheel-and-axle set, as in publication US-3 480 095 or GB-2 038 005. The measuring of the said yielding may also be based on an electromechan¬ ical device which converts the change in the distance into an electric signal, as in publications GB-2 178 546 and DE- " 1 030 206. All of these have the serious drawback that they are based on the deformation of the spring suspension of the vehicle itself. In terms of weighing, no structure applicable as a spring conventional in the commercial sense is by its properties sufficiently steady and sufficiently constant during use in order for a measuring based on its yield to provide even a nearly sufficiently accurate result of measurement. An especially inaccurate measuring result is obtained if the vehicle has leaf springs, since in that case the measuring result is affected not only by the non- linearity of the spring but also by friction between the leaves of the spring and the friction forces produced in the attachment of the ends. " In addition, all the conven¬ tional springs involve the problem that, depending on the extent of the yield movement, they are always somewhat non¬ linear, which is indeed often specifically aimed at in the planning of the spring suspension. Measuring the load by means of such a non-linear yield movement would require a very complicated calculating capacity in the vehicle. Publication DE-811 434 discloses a structure otherwise corresponding to those described above, but the yield move¬ ment produced in conventional leaf springs under the effect of the loading weight is measured as an increase in the pressure of the hydraulic fluid, but since the sensor cyl¬ inders are coupled in parallel as regards their hydraulics, the total weight is obtained from the mean. This structure has the advantage that the signals coming from the differ¬ ent sides of the vehicle can be processed simply and reli¬ ably, and an increase in the load at any given time can be detected from the pressure difference. Since even this is based on a deformation of the actual spring suspension, it involves, nevertheless, all the same errors due to the non- linearity of the spring suspension and to friction as were described above. The purpose of the invention is to provide an arrangement in a vehicle or the like for weighing the loading weight, an arrangement which provides a reliable result of measur¬ ing the loaded weight regardless of the type of the spring suspension of the vehicle and regardless of any non- line'arity and friction factors possibly involved in it, and also'' provides a reliable measuring result regardless of the position of the vehicle on terrain or of the location of the load in the vehicle. In addition, it is an object of the invention to provide an arrangement which can be dis¬ connected in such a manner for the duration of the driving of tie vehicle that it will not in any manner affect, for example, the functioning of the spring suspension of the vehicle, and that the continuous movement of the wheels of the vehicle during driving will not stress the measuring system. It is a further object of the invention to provide an arrangement which can be installed in connection with the already existing components of the spring suspension of the vehicle or the structures of its chassis so that the number of significant components is not increased and their operation or maintenance is not complicated. It is an addi¬ tional object of the invention to provide an arrangement which is by structure simple and reliable in operation and the price of which is so advantageous that the arrangement can be installed in all vehicles according to need. The arrangement according to the invention provides a cru¬ cial improvement with respect to the disadvantages pre¬ sented above and realizes the objects defined above. In order to achieve this, the arrangement according to the invention is characterized in what is presented in the characterizing clause of Claim 1. It can be deemed to be the most important advantage of the invention that a precise and reliable weighing result is always obtained of each load batch of a vehicle, trailer, railway wagon or the like, regardless of the structure of the wheel-and-axle sets or the spring suspension of the vehicle, regardless of the position of the vehicle, such as its tilt on terrain during loading, and regardless of the location of the load in the vehicle. There is the addi¬ tional advantage that the arrangement is economical in terms of its acquisition costs and can be installed in connection with the spring system of the vehicle in such a manner that it will have no detrimental effects on the operation or maintenance of the vehicle. It is a further advantage that, by means of the arrangement, information can be provided into the driver's cabin of the vehicle and/or to the loader outside the vehicle, regarding the weight of the load even during the loading, and not only after the loading, as has been the case with prior art techniques. Obtaining the correct load and, on the other hand, the correct total weight for a vehicle or a vehicle combination also enables an optimal transport result to be achieved. On the other hand, a system indicating the total load can be used for control, both by authorities and by parties to a business deal. The invention is described below in greater detail with reference to the accompanying drawings, in which Figure 1 depicts a longitudinal section of a sensor device according to the invention, in the resting position, Figure 2 depicts a section through A-A in Figure 1 of the sensor device of Figure 1, in the measuring position, Figure 3A depicts a longitudinal, section of another embodi¬ ment of the invention, in the resting position, Figure 3B depicts a section through B-B-B of the structure according to Figure 3A, Figure 3C depicts a cross section through C-C of the struc¬ ture of Figures 3A and 3B, Figure 4A depicts the structure of Figure 3A, in the mea¬ suring position, Figure 4B depicts the same representation as Figure 3B, but in the measuring position, Figure 4C depicts the representation of 3C, in the measur¬ ing position, Figure 5A depicts a vehicle in which sensor devices accord¬ ing to the invention have been installed, and Figure 5B depicts the vehicle of Figure 5A, in which the measuring arrangement according to the invention is de¬ picted schematically in its entirety. Figures 5A and 5B depict the system according to the inven¬ tion for weighing the loading weight, based on the measur¬ ing of fluid pressure, installed in a vehicle 17. In this case the vehicle 17 is a lorry the bogie wheels 18 of which are capable of being raised for the duration of loading. The front axle set of the vehicle is indicated in general by reference numeral 29 and the rear axle set by reference numeral 19, the wheels of the lorry rotating in the axle sets. These axle sets 29, 19 are coupled to the frame 22 of the vehicle by mediation of springs 21 and respectively 20. Typically the front spring suspension 21 is made up of helical springs, whereas the rear spring suspension 20 is made up of leaf springs. The axle sets 29 and 19 are, fur¬ thermore, coupled to the frame of the vehicle by means of sensor devices 7, which, according to a preferred embodi¬ ment- of the invention, are at the same time shock absorbers connected with the spring suspension of the vehicle. One attachment point 41 or 42 of the sensor devices is attached to the axle set of the vehicle, and the other attachment point 42 or 41 is respectively attached to the frame of the vehicle, in which case the sensor devices are in a way installed in parallel with the springs. Thus, in the case depicted in Figures 5A and 5B, there are four of these sensor devices, the sensor devices connected with the front spring suspension of the lorry being installed inside the said, helical springs 21 and the sensor devices connected with the rear axle set 19 of the lorry being installed next to the leaf springs 20. Depending on the type of the spring suspension of the vehicle, the placement of the sensor devices can, of course, also be some other, but in general- it is most advantageous to install them in connection with each axle set as close as possible to the wheels and/or the sides of the vehicle. If the wheels 18 are not capable of being raised off the ground for the duration of loading, their axle set must also be provided in a corresponding manner with two sensor devices, a situation which is not depicted in the figures. Figure 5B depicts a hydraulics pump 1, a suction tube 2, a pressure tube 3, an open-shut valve 4, preliminary-pressure tubes 5, control chambers 6, back-pressure valves 8, a pressure tube 9 leading to the meters, a controllable pres¬ sure limiter 10, a second open-shut valve 11, a return tube 12, pressure meters 13, a pressure sensor 14, a display unit 15, and operating controls 16. In this case all of the sensor devices 7 have been coupled by means of the pressure tube 9 directly in parallel with each other, in which case, during loading, the mean of the pressure increases produced by all the four sensor devices is transmitted in the mea¬ suring fluid volume to the pressure sensor 14. This pres¬ sure sensor 14 converts the pressure, or in this case rath¬ er the pressure difference between the initial state and the loaded state, into an electric signal, which is dis¬ played in the desired form, for example in digital form, as a pressure reading in the driver's cabin of the vehicle. The display may also be arranged, by means of an electrical connection, as a secondary display or as the principal display, for example, within the range of vision of the loader outside the vehicle. In other respects the hydrau¬ lics and its components are of conventional technology, and they are therefore not described here in greater detail. The measuring system may also be arranged in some other manner, for example so that the hydraulic pressures of the sensor devices of the front axle set 29 are coupled in parallel as one measuring-fluid volume and this mean is detected by the first pressure sensor, and the hydraulic pressures of the sensor devices of the rear axle set 19 are coupled in parallel as a second measuring-fluid volume and the mean pressure corresponding to this is detected by the second pressure sensor, whereafter the electric signals from these two pressure sensors are summated, or a mean is otherwise formed of them, which, converted and calibrated as the real loading weight, is displayed in the display device 15. In this case the detecting and the forming of the means thus take place as a hierarchic system. If there are sensor devices connected also with the axle set 18, it is possible not only to couple the hydraulic pressures of all the sensor devices in parallel as one measuring-fluid volume, but also to form, each separately, the hydraulic values detected by pressure sensors corresponding to the axle sets 29, 19, 18, and to form from them electrically a displayed result, or alternatively the axle sets 18 and 19 can be coupled hydraulically in parallel as a measuring- fluid volume and the detected signal corresponding to these can be combined with the detected signal regarding the front axle set 29. Other ways of forming the hierarchy can also be envisaged. In principle, the pressure of each sensor device can be detected in its own measuring-fluid volume, s-eparately by the pressure sensor, but often this is not expedient, since in such a case there will have to be several pressure sensors, and control of their working condition will be complicated and the price of the system will even otherwise increase. Figure 1 depicts the sensor device 7 according to the in¬ vention in greater detail, in a longitudinal section, with the definer piston 23 in the resting position,, the sensor device 7 serving as a conventional gas-filled shock ab¬ sorber in the spring system of the vehicle 17. Figure 2 depicts the sensor device of Figure 1- in a longitudinal section perpendicular to the plane of Figure 1, but with the definer piston 23 in the measuring position. The func¬ tioning of the sensor device is as follows: When the vehicle arrives and stops at the loading site, by means of the pressure.-generation system of the hydraulics, shown in Figure 5B, there is raised in the pipe system a preliminary pressure which is transmitted to each sensor device 7 via the pressure connection unit 24. According to the invention, this preliminary pressure is sufficiently high in order for the unattached definer pistons 23 tightly inside the main cylinder part 25 in each sensor device of the vehicle to press against the end 27 of the principal 1 piston part 26, the end 27 being inside the principal cyl¬ inder part 25, and to lengthen even thereafter, at least by a differential, small amount, each sensor device of the vehicle. This means that, when the point of departure is the sensor-device 7 length caused by the weight of the vehicle itself and any previous load, i.e. the distance between the attachment points 41, 42 of the sensor device, the said telescopic lengthening of the sensor device under the effect of the preliminary pressure means that the said distance increases, whereby the frame 22 of the vehicle is thus raised somewhat upward from the initial state and upward from the axle sets at each of their points. Thereafter the hydraulics system is closed, i.e. it is locked at this preliminary pressure so that the measuring- fluid volume will not, and cannot, change. At the same moment the display device of the measuring system is zeroed. In this manner, every time that the weighing of a load begins, the zero point of the entire measuring system is thus calibrated. When a load is then introduced on top of the vehicle frame 22, the pressure in the measuring- fluid space 28 inside the principal cylinder part 25 in¬ creases by a corresponding amount and is transmitted via the connection unit 24 to the pressure tube 9 which leads to the meters and from which it is detected by means of a pressure sensor or pressure sensors, as described above, Thus, by the measuring-fluid volume is meant here that total volume of the measuring-fluid spaces and tubes which has been locked to be invariable. The liquid spaces belong¬ ing to this at any given time depend on the measuring and display arrangement described above in connection with Fig¬ ure 5B. Since what is in question is an unchanging fluid volume, owing to its non-compressibility, the principal cylinder part 25 and the principal piston part 26 will not, at least notably, move in relation to each other during loading; as a result, the frame 22 of the vehicle remains stationary in relation to the axle sets 29, 19. This pro¬ vides the advantage that the actual spring suspension 21, 20 of the vehicle itself does not have any effect on the weighing result, since the load is not resting on them but on the sensor devices 7 and since, owing to the movement- preventing effect of the sensor devices, the error factors dependent on the movement of spring systems have no signif¬ icance in terms of the measuring result. Since the calibra¬ tion is carried out at the beginning of each loading round, this provides a special advantage in, for example, traffic in.which loads are picked up from several places and in which, each additional load can be weighed separately, and, for example, be invoiced immediately. The total weight of the load is, of course, in this case obtained as the sum of the partial loads. In the arrangement according to the invention the setting of the preliminary pressure is considerably simple and clear even if the vehicle is unevenly loaded or on an in¬ clined base, in which case the end 27 of the principal piston part 26 in each sensor device is at a different point of the length of the principal cylinder part 25. When, at " the beginning of ~ the weighing, the pressing of the measuring fluid in the pipe systems into the sensor devices is started in the manner described above, the definer pis¬ tons 23 start moving approximately simultaneously in each sensor device from its upper part 28, which is that end which faces away from the principal piston part 26 of the principal cylinder part 25; in practice this end can, of course, also be installed downward in the structure. At this time the hydraulic fluid has only as much pressure as is necessary for overcoming the sealing friction of the definer pistons against the walls of the principal cylinder parts 25. The pressure increases in steps and definitely at the moment when the last one of the definer pistons comes into the measuring position. This event of the definer pistons which have reached their measuring positions previ¬ ously does not have any effect on the pressure. Now that the pressure is increased to the actual preliminary pres¬ sure, which may be in the order of, for example, 50 bar, the consequence of this is that the sensor devices lengthen telescopically and raise the frame 22 of the vehicle upward from the axle structures 29, 19. It is expedient to arrange the preliminary pressure in such a way that the telescopic lengthening of the sensor device is always approximately the same at the beginning of loading, regardless of the initial load situation. This means that, at the beginning of the loading of an empty lorry the preliminary pressure is a vehicle-type-specific constant or the like, and that the preliminary pressure is greater when an additional loading of the vehicle is being carried out, the prelimi¬ nary pressure being always higher the greater the load is at the beginning of the loading. This adjustment of the preliminary pressure can either be carried out manually by the driver or it can be controlled automatically according to the load, in which case it may consist of a suitable number of fixed preliminary pressures, or it may change without steps. The planning and manufacture of such a con¬ trol mechanism is application of prior art technology and is therefore not described here in greater detail. When the loading has been carried out and the intention is to start the vehicle, the hydraulic fluid is released from the chamber 28, whereupon the pressure disappears and the frame 22 of the vehicle is lowered to rest on its springs in the normal position. If the hydraulic fluid is actually sucked out of the measuring-fluid space, for example, by means of a vacuum, the definer piston 23 in each of the sensor devices rises into its resting position against the end 43 of the principal cylinder part. Even if the definer pistons are not drawn fully into their resting positions in this manner, at the time the driving is started, at which time the principal cylinder part and the principal piston part again begin functioning as actual shock absorbers, it does happen that in them the pneumatic pressure pushes the definer piston into the said resting position, and thereby it also pushes the remainder of the hydraulic fluid before it into the tube system, as long as there is no counter- pressure in the tube system. On that side of the definer piston which is away from the principal piston part 26 there is preferably provided a protrusion 29 which is made of a resilient material and, when the definer piston is brought to its final resting position, clings to the open¬ ing 30 in the end 43 -of the principal cylinder part 25. The purpose of this is to keep the definer piston firmly in its resting position during the movement of the vehicle so that its unnecessary back-and-forth movement will not cause wear or other detrimental effects. During the driving the prin¬ cipal cylinder part 25 and the principal piston part 26 thus serve as a normal shock absorber, such as a gas- filled absorber, and so it is not necessary to describe their structure here. That end 31 of the principal piston part 26 which faces away from the principal cylinder part has valve devices 32 which make sure that, when the definer piston comes to the measuring position, any excess of gas can discharge and, when the definer piston 23 moves to its resting position, any necessary gas volume can flow back. The structure of this valve means 32 is not described here in greater detail. The embodiment in Figures 1 and 2 is completely rigid dur¬ ing loading, and thus does not yield during the loading of the vehicle; this is well suited in connection with a vehi¬ cle spring suspension made up of multiple-leaf leaf springs, which is an especially difficult target owing to its high yield friction. The stress due to shock-like load¬ ing can, however, be absorbed by a suitable spring and/or valve structure which yields under the impact of a shock but returns the fluid volume or maintains it unchanged. Figures 3 and 4 show another embodiment of the sensor de¬ vice according to the invention, which is capable of yield¬ ing during loading. Figures 3A-C depict the resting posi¬ tion, which corresponds to Figure 1, and Figures 4 -C de¬ pict the measuring position, which corresponds to Figure 2, the same reference numerals having been used for the corre¬ sponding parts. What has been described above is thus largely applicable also to the operation of the device according to Figures 3A-C and 4A-C. When weighing is started using the alternative according to Figures 3 and 4, the actuating piston 33 is transferred in the actuating unit 44, by means of pressure 34, from the resting position of Figure 3C to the measuring position of Figure 4C to be against the shoulder 36 in the frame of the unit. Thereupon the definer piston 23 moves under the ef¬ fect of the hydraulic fluid coming via the connection unit 46, in the same manner as described previously, against the end 27 of the principal piston part 26. In this arrangement the stroke volume of the actuating piston 33 in each sensor device is sufficient for the definer piston always to come against the end 27 of the principal piston part, regardless of the mutual position of the principal cylinder part 25 and the principal piston part 26. Since the stroke volume of the actuating piston is always constant and since the pressure 34 is always arranged to be sufficiently high to take the actuating piston 33 against the shoulder 36, it follows from this that that portion of the hydraulic fluid which does not fit in the measuring fluid chamber 28 moves via the connection unit 47 to the measuring unit 45 of the sensor device. The measuring unit comprises a measuring piston 37 and a calibrated spring 38. When the measuring fluid pushes into the measuring unit, the measuring piston 37 moves against the force of the spring 38, whereupon the pressure in chamber 28 depends, accordingly, on the trans¬ fer of the measuring piston 37. The measuring-fluid volume thus being always constant, it follows that the pressure in the chamber 28, measured via conduit 48 by means of the pressure sensor 39, is, in accordance with the spring force of the spring 38, i.e. usually linearly, dependent on the mutual position of the principal cylinder part 25 and the principal piston part 26. The signal transmitted by the pressure sensor 39 is processed according to the arrange¬ ment described previously, which includes zeroing the dis¬ play in this situation. When the vehicle is then being loaded, there occurs in this embodiment, contrary to the rigid embodiment described previously, slight lowering of the frame 22 of the vehicle. As the frame thus lowers, which means the pushing of the principal cylinder part 25 and the principal piston part 26 deeper one inside the other, the pressure of the measuring- fluid volume, which in this case is made up of the space 28, the volumes of the actuating unit 44 and the measuring unit 45, and the connection unit volumes, rises linearly, since the constant volume moves the measuring piston 27 over the corresponding distance against the spring force of the calibrated spring 38; this . pressure increase can be converted into a display corresponding to the pressure, as described previously. Since here the frame 22 and the axle sets 29, 19 move slightly in relation to each other during loading, the measuring arrangement using this sensor device alternative is in theory not quite as precise as the mea¬ suring method based on a rigid sensor device described above, but in practice the difference is slight and, .in uses in which the loading is necessarily shock-like, this alternative is superior in terms of the durability of the structures of the vehicle. In fact, if the rigidity of the spring 38 is adjusted to an infinite value, the situation is, with the exception of the details, as in the embodiment of Figures 1 and 2, and the more resilient the spring 38 is made, the more the frame of the vehicle yields under loads and shocks. There is, however, a lower limit for the rigid¬ ity of the spring 38; the spring cannot be made more resil¬ ient than that. The measuring spring 38 must namely have a sufficient quantity of linear or other precisely known spring force and a sufficient remaining distance of move¬ ment of the measuring piston 37 at the stage when in the space 28 there prevails the preliminary pressure by which the frame 22 of the vehicle has been raised upward from its natural position. Even in this case, the effect of the actual spring suspension on the measuring result is smaller than in the alternatives according to the state of the art, the reason being that the slight lowering of the frame, controlled by the sensor device, toward the axle sets 19, 29 in many cases means only a change in the actual clear¬ ances in the spring suspension or the like. The alternative shown in Figures 3A-C and 4A-C is suitable for use in con¬ nection with spring suspensions consisting of helical springs, torsion-bar springs, parabolic springs, or other springs which have low yield friction, since in this case any possible errors are further minimized. When the measuring has been carried out and the intention is to start driving the vehicle,- the pressure 34 is re¬ leased, whereupon the actuating piston 33 returns under the effect of the return spring 40 to its resting position, whereupon, as the spring 38 returns to its resting posi¬ tion, the measuring fluid from the space 28 and also from the measuring part flows into the fluid space 41 of the actuating unit, as can be seen in Figures 3B and 3C. At this time ' the definer piston 23 also withdraws, under the effect of the suction of the hydraulic fluid, to the end 43 of the principal cylinder part, where it becomes locked or is locked and where it does not constitute an obstacle to the relative movement of the principal cylinder part 25 and the principal piston part 26 during the driving and does not make any unnecessary reciprocal movement. Only two embodiments according to the invention have been described in detail above, but also other alternatives are possible. Thus, the telescopic operations presented are not the only possible ones; it is possible to use a mechanism of any type by means of which the force produced by weight between the axle structure 19 and/or 29 and the frame 22 can be converted into pressure in the manner defined in the characteristics of the invention. Thus, for example, it is possible to use various lever mechanisms or a mechanism which tends to convert relative movement into a change of volume. It is, however, a specific requirement that the mechanism must function also in reverse, so that it is possible to raise also the frame of the vehicle, at least slightly, by means of a pressure increase, i.e. the prelim¬ inary pressure. Some bellow-type or case-type (as in baro¬ meters) alternatives may be usable in addition to the tele¬ scopic alternative described. Especially in the resilient alternative, the springs of the sensor device may be not only spiral springs as described but also other types of springs known per se, made of a solid material, or gas springs or gas-liquid springs, in which case it must, how¬ ever " , be taken into account that specifically the measuring spring must be of such construction that it is preferably linear over as wide an area as possible and additionally insensitive to temperature changes and other environmental effects. In a case in which the sensor device also consti¬ tutes a shock absorber, the shock-absorption portion may be of any known type. The retainer mechanism of the definer piston for locking it in the resting position may be of various types, which can be automatic or can be separately lockable. It is clear that the arrangement of the invention includes tube systems, conduits, gaskets in for example the definer piston, valves and other means in themselves con¬ ventional for producing the intended operation.

Claims: Claims 1. An arrangement for measuring the loading weight of a vehicle or a corresponding unit by using sensor devices which are installed in the vehicle between the frame struc¬ ture (22) and the wheel-and-axle sets (19, 29) or similar means in such a manner that the principal cylinder part (25) belonging to the sensor device (7) is connected to one of them and the principal piston part (26) respectively to the other, in which case there is between them inside the principal cylinder part a measuring-fluid space (28), the output signals of the sensor devices are at least in pairs coupled in parallel in order to obtain the loading weight via means, or via a sum, and the said output signals are based on a change in the pressure of the measuring-fluid spaces of the sensor devices, characterized in that the measuring-fluid spaces (28) in the sensor devices (7) are formed separately for each measuring round by pressing the definer pistons (23) inside the principal cylinder parts by a sufficient pressure of the measuring fluid from the rest¬ ing position to the measuring position, in which each of them is in one of its extreme positions and delimits the measuring-fluid volume, that the measuring-fluid volumes or volume are/is closed at this pressure, with respect to which the indicator devices are calibrated on each measur¬ ing round, and that the loaded weight is detected from the pressure increase appearing as a result in this fixed fluid volume or in each fixed fluid volume. 2. An arrangement according to Claim 1, characterized in that the resting position of the definer piston (23) is the first extreme position of the principal cylinder part (25), to which position the definer piston is drawn by removing the measuring fluid from the measuring space (28) of the principal cylinder part, whereupon the principal piston part (26) is free to move in relation to it. 3. An arrangement according to Claim 2, characterized in that the first extreme position is against that end (43) of the principal cylinder part which is away from the princi¬ pal piston part (26) and the other extreme position is against the end (27) of the principal piston part (26). 4. An arrangement according to any of Claims 1-3, -charac¬ terized in that the said sufficient measuring-fluid pres¬ sure for moving the definer piston (23) to the measuring position is such that it raises the frame (22) of the vehi¬ cle being weighed at all its support points upward over at least a differential, small distance against gravity, the corresponding measuring-fluid volume or measuring-fluid volumes being closed, and this said fluid pressure being set on each separate measuring round as the zero point for the weight measurement. 5. An arrangement according to any of the above claims, characterized in that the two sensor devices (7) located on each axle (29, 19, 18) and corresponding to the wheels or other support points on the opposite sides of the vehicle are coupled in parallel, and these axle-specific hydraulic or electrical circuits are further coupled hierarchically into bogie-specific and further into vehicle- or trailer- specific or corresponding hydraulic or electrical circuits. 6. An arrangement according to any of Claims 1-4, charac¬ terized in that all of the sensor devices are directly coupled in parallel with each other into one measuring- fluid volume in order to obtain a mean signal or a sum signal. 7. An arrangement according to any of Claims 1-4, charac¬ terized in that each sensor device (7) with its actuating means (44, 45) constitutes a separate measuring-fluid volume. 8. An arrangement according to any of the above claims, characterized in that each sensor device. (7) , or each means or mechanism transmitting the effect of the load to it, is located as close as possible to the sides of the vehicle or corresponding unit, or to its wheels, or to other corre¬ sponding support points. 9. An arrangement according to any of the above claims, characterized in that the principal cylinder part (25) and the principal piston part (26) of the sensor device consist of the cylinder part and piston part of the shock absorbers belonging to the spring system of the vehicle. 10. An arrangement according to any of the above claims, characterized in that each measuring-fluid volume consists of a substantially unyielding fixed volume and that this volume is in the main the measuring-fluid space (28) inside the definer piston in the measuring position and the prin¬ cipal cylinder part (25), in which case loading does not cause substantial movement of the frame structure (22) in relation to the other attachment points of the sensor devices. 11. An arrangement according to any of Claims 1-9, charac¬ terized in that the measuring-fluid volume is delimited by a springed (38) measuring piston (37), in which case an increase in the pressure of the fluid volume produces a movement of the measuring piston (37) against the spring force of this calibrated spring (38) and at least a small movement of the frame structure (22) relative to the other attachment point of the sensor device (7) during loading, and that the rigidity of the said spring (38) is as linear as possible. 12. An arrangement according to Claim 11, characterized in that the measuring-fluid volume in its entirety is a pre- determined constant volume, a substantial portion of which is transferred into the measuring-fluid space (28) for the measuring round, by means of a movement limited by the shoulder (36) or the like of the actuating piston (33) of the actuating unit (44). 13. An arrangement according to any of the above claims, characterized in that the definer piston (23) has means (29) for locking it detachably in the resting position.

Inventors: OUNASLEHTO ERKKI E K, OUNASLEHTO, ERKKI, E., K.
Applicants: OUNASLEHTO ERKKI, OUNASLEHTO, ERKKI, E., K.
Application year: 1989
Main classification: B60P5
IPC codes: B60P5, G01G19