JP2009175148A - Fork lift truck equipped with force measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fork lift truck allowing the accurate detection of axle load in a reliable, strong and nonsensitive form. <P>SOLUTION: A force measuring apparatus is formed as a bending force measuring apparatus 2 and formed additionally and at least partially as a travel mechanism constitutive member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a forklift provided with a force measuring device.

  Forklifts can tip forward during unfavorable conditions, especially when cargo increases. It is known to detect a rear axle load, that is, an axle load by a force measuring device, thereby detecting a tilting risk. At the start of the tilting process, the axle load is equal to zero.

  A front forklift with a device for measuring axle loads is known from German Offenlegungsschrift 3,422,837. In order to measure the axle load, in one configuration, a pressure sensor is provided at the axle support location. This arrangement has the disadvantage that the lateral force generated at the axle support, particularly during driving, significantly deteriorates the measurement results. In another configuration, the amount of elastic deformation of the axle body is measured by a strain gauge. This configuration has the same problems and provides a particularly inaccurate measurement result because of the gray cast iron material usually used for axle fabrication.

  A counterweight-type forklift having a front-side lifting device and a rear-side counterweight is known based on German Patent Application No. 102006028551. In order to be able to detect the axle load as accurately as possible, the force detector is configured as a double shear force detector. This double shear force detector is incorporated in the rear axle. In this known forklift, the axle can be equipped with axle load detection means relatively easily. In this case, changes in the vehicle frame, such as counterweight or axle suspension, are not necessary. Shear force detectors are sensitive to force-introduced displacements, and therefore have the disadvantage that significant deviations can occur between measured results and actual axle loads, especially during driving. Yes.

German Patent Application Publication No. 3422837 German Patent Application Publication No. 102006028551

  Accordingly, it is an object of the present invention to provide a forklift that allows accurate detection of axle loads in a reliable, robust and insensitive manner.

  In order to solve this problem, in the configuration of the present invention, the force measuring device is formed as a bending force measuring device, and is additionally formed at least partially as a traveling mechanism constituent member.

  According to an advantageous configuration of the invention, the bending force measuring device has a measuring section, in which the deformation produced by the bending load can be measured.

  According to an advantageous configuration of the invention, the bending force measuring device has at least one elastically deflectable element.

  According to an advantageous configuration of the invention, the elastically deflectable element has a parallelogram guide.

  According to an advantageous configuration of the invention, the elastically deflectable element is formed as a double-deflecting beam.

  According to an advantageous configuration of the invention, the bending force measuring device has at least one measuring sensor, by means of which the amount of bending of at least one elastically deflectable element can be measured. .

  According to an advantageous configuration of the invention, the bending force measuring device has a plurality of measuring sensors, in particular 16 measuring sensors.

  According to an advantageous configuration of the invention, the measurement signals of a plurality of measuring sensors are compared with each other and / or superimposed on each other for detection of the bending force.

  According to an advantageous configuration of the invention, the signal components of the lateral forces which are detected simultaneously in each case without affecting the overall deflection of the individual measurement signals are eliminated from each other and / or calculated from each other. A plurality of measurement sensors are arranged and / or connected to each other so that they can be removed.

  According to an advantageous configuration of the invention, the plurality of measurement sensors are arranged such that the temperature-dependent dependence of the individual measurement signals of the plurality of measurement sensors is sufficiently eliminated from each other at least in a predetermined temperature range. Are arranged and / or connected to each other.

  According to an advantageous configuration of the invention, a plurality of measurement sensors are arranged and / or connected to each other to generate redundant measurement signals.

  According to an advantageous configuration of the invention, at least one measurement sensor (for example a strain gauge) is provided in the symmetry plane of the elastically deformable element, the redundant measurement sensor being parallel to the symmetry plane on both sides. Placed on a flat surface (eg, a split strain gauge).

  According to an advantageous configuration of the invention, an electronic processing unit is provided for receiving the measurement signal of one measurement sensor or the measurement signals of a plurality of measurement sensors.

  According to an advantageous configuration of the invention, the processing unit is adapted to detect the bending force from the individual measurement signals.

  According to an advantageous configuration of the invention, a temperature measuring device is provided, so that the processing unit corrects the measurement error due to the temperature of the individual measurement signals and / or of the detected deflection force. It has become.

  According to an advantageous configuration of the invention, a memory unit is provided in which correction parameters for different temperatures are filed.

  According to an advantageous configuration of the invention, the at least one measuring sensor has a strain gauge.

  According to an advantageous configuration of the invention, at least one measuring sensor is arranged inside the bending force measuring device.

  According to an advantageous configuration of the invention, at least one measuring sensor is arranged in the lateral notch of the bending force measuring device.

  According to an advantageous configuration of the invention, the bending force measuring device has a plurality of notches, each of which has at least one measuring sensor, in particular two measuring sensors, in particular four measuring sensors. Is arranged.

  According to an advantageous configuration of the invention, the measurement signal of one measurement sensor arranged corresponding to one measurement section, for example arranged in one notch, is arranged corresponding to the other measurement section, for example One which is comparable to the measurement signal of the other measurement sensor arranged in the other notch and / or the processing unit is arranged corresponding to one measurement section, for example one arranged in one notch The measurement signal of the other measurement sensor is compared with the measurement signal of the other measurement sensor arranged corresponding to the other measurement section, for example, arranged in the other notch.

  According to an advantageous configuration of the invention, the measurement sensor is formed as a strain gauge, which is a component of an electrical bridge circuit, in particular a Wheatstone measurement bridge.

  According to an advantageous configuration of the invention, some of the strain gauges of the bridge circuit are arranged in one notch of the bending force measuring device and another strain gauge of the bridge circuit is arranged in the bending force measuring device. It is arrange | positioned in the other notch.

  According to an advantageous configuration of the invention, the measuring sensor is formed as a strain gauge, some of which are components of the first electrical bridge circuit, and another strain gauge, It is a component of the second electrical bridge circuit.

  According to an advantageous configuration of the invention, a protective device is provided which protects one or more measuring sensors against contamination and / or damage.

  According to an advantageous configuration of the invention, the protective device has a shrink ring.

  According to an advantageous configuration of the invention, at least one measuring sensor is arranged below the protective sealing material.

  According to an advantageous configuration of the invention, the deflectable element is formed as a deflecting beam.

  According to an advantageous configuration of the invention, the bending force measuring device is formed as an axle, in particular a rear axle and / or a steering axle, and / or as a component of an axle suspension.

  According to an advantageous configuration of the invention, the bending force measuring device is formed as a support with an integral, in particular coaxial journal, for suspension on a vehicle, in particular a vehicle frame.

  According to an advantageous configuration of the invention, one lateral cutout is machined next to each oscillating journal, in particular a horizontal lateral cutout that extends consistently, the lateral cutout being , Each of which is divided into upper and lower parts by measurement sections.

  According to an advantageous configuration of the invention, a deflection force measuring device is formed for detecting the axle load.

  According to the present invention, firstly, the additional mounting of the force measuring device to the individual axle components requires one part, and the other is easily disturbed and in particular the axle load. It has been observed that this leads to a complex system that makes reliable detection impossible. Furthermore, it has been found that these problems cannot be effectively addressed by the use of very complex special sensors, such as double shear force sensors.

  The special feature of the forklift according to the present invention is that the traveling mechanism constituent member is formed such that the traveling mechanism constituent member, for example, the axle constituent member or the axle suspension constituent member, simultaneously assumes the support function and the measurement function. Particularly advantageously, a deflection load is generated in the measuring section, and the amount of deformation caused by the deflection load is measured by one or more measuring sensors arranged in the force measuring device, on the basis of which It may be proposed to form the travel mechanism component so that the force and ultimately the axle load can be detected. This arrangement makes it possible to obtain a relatively accurate and reproducible measurement within the axle load detection frame.

  In this case, it may be proposed that the bending force measuring device is a part of the center axle body of the axle attached to the vehicle frame. In this case, the possibility of rear installation is easily provided by exchanging the center axle body of the axle of a conventional forklift with the center axle body provided with the axle load detecting means according to the present invention.

  The bending force measuring device has at least one elastically deflectable element. This element may advantageously be formed as a deflecting beam or a double deflecting beam. In particular, the elastically bendable element may be formed as a support with two integrally formed coaxial swing journals spaced apart from each other in the longitudinal direction of the vehicle. Both swing journals are provided for suspending the axle on the vehicle frame, whereby the support constitutes a component of the axle suspension located in the power flow. Further advantageously, a horizontal lateral notch that extends consistently adjacent to each oscillating journal may be machined into a travel mechanism component formed as a deflection force measuring device. The lateral cutouts are divided up and down by measuring sections provided as deflected beams.

  Particularly advantageously, it may be proposed that the elastically deflectable element has a parallelogram guide. This can be obtained, for example, by the configuration of the elastically deflectable element as a double deflecting beam. This configuration is particularly insensitive to disturbing factors that worsen the measurement results, such as lateral forces and force-induced displacements, thereby ensuring that even during driving, even on uneven roads and steering maneuvers. Accurate measurement of axle load is possible.

  In a special configuration, the bending force measuring device has at least one measuring sensor, which can detect the amount of bending of at least one elastically deflectable element. In particular, in order to obtain reproducible measurement results, it is proposed that a total of two double-deflection beams are equipped with a total of eight measurement sensors (four measurement sensors per double-deflection beam). May have been.

  A very particularly accurate result can be obtained according to the invention when an additional measuring sensor is provided in the form of redundancy. For example, a configuration in which two double-deflecting beams are equipped with a total of sixteen measuring sensors (eight measuring sensors per double-deflecting beam) is particularly reliable and accurate.

  Further advantageously, the special arrangement is configured such that the measurement signals of a plurality of measuring sensors are compared with each other and / or superimposed on each other for the detection of the bending force. For example, the signal components of the lateral force of the individual measurement signals that are detected simultaneously in each case without affecting the overall deflection are eliminated from each other and / or from each other, for example by an electronic processing and evaluation unit. It may be proposed that a plurality of measurement sensors are arranged and / or connected to each other so that they can be removed by calculation. Additionally or alternatively, the plurality of measurement sensors may be arranged such that the temperature-dependent dependence between the individual measurement signals of the plurality of measurement sensors is sufficiently eliminated from each other at least in the predetermined temperature range. It may be proposed that they are arranged and / or connected to each other.

  As already mentioned, a plurality of measurement sensors may be arranged to generate redundant measurement signals and / or connected to each other in order to obtain particularly accurate and reliable measurements. In an advantageous configuration, at least one measurement sensor (eg one or more strain gauges) is arranged in the plane of symmetry of the elastically deformable element, and in the form of redundancy, at least one further measurement. The sensors are arranged in planes parallel on both sides with respect to the symmetry plane. The additional redundant measurement sensor may be, for example, one (or more) divided strain gauges with portions electrically connected in parallel. In this way, the disturbance force can be effectively canceled even during redundant measurement.

  In a special configuration, an electronic processing unit is provided. The processing unit receives the measurement signal of one measurement sensor or the measurement signals of a plurality of measurement sensors and detects the bending force and / or axle load from the individual measurement signals. In addition, a temperature measuring device may be provided. The temperature measuring device transmits the temperature measurement value to the processing unit, which corrects the measurement error due to the temperature of the individual measurement signals and / or of the detected deflection force. In a special configuration, a memory unit is provided. In this memory unit, correction parameters for different temperatures are filed.

  In a special configuration, at least one measuring sensor is arranged inside the bending force measuring device. For example, at least one measurement sensor may be arranged in a lateral notch of the bending force measuring device. In a special configuration, the deflectable element has a plurality of notches, in which at least one measuring sensor, in particular two measuring sensors, in particular four measuring sensors, are respectively arranged. .

  In order to obtain particularly reliable measurement results, in a special configuration, the measurement signal of one measurement sensor arranged in one notch is combined with the measurement signal of the other measurement sensor arranged in the other notch. Comparable and / or the processing unit compares the measurement signal of one measurement sensor arranged in one notch with the measurement signal of the other measurement sensor arranged in one notch Has been proposed.

  The measurement sensor may be formed as a strain gauge, for example. This strain gauge is a component of an electrical bridge circuit, in particular a Wheatstone measurement bridge. In order to avoid lateral forces and / or torsional forces from degrading the measurement results, several of the bridge circuit strain gauges are advantageously arranged corresponding to the first measurement section, It may be proposed that another strain gauge is arranged corresponding to another measurement section. For example, some of the strain gauges in the bridge circuit may be placed in the first notch of the flexure force measuring device, whereas another strain gauge in the bridge circuit is another in the flexure force measuring device. Located in the notch.

  For example, the configuration of a flexural force measuring device with a plurality of redundant measuring circuits works quite reliably. In particular, according to the present invention, it is proposed that some of the strain gauges are components of the first electrical bridge circuit and another strain gauge is a component of the second electrical bridge circuit. May have been. Furthermore, additionally, at the same time, some of the strain gauges of the first electrical bridge circuit are arranged corresponding to the first measurement area, for example the first notch, whereas the first Particularly reliable and reproducible measurement results can be obtained if another strain gauge of the electrical bridge circuit is arranged corresponding to the second measurement region, for example the second notch. Further advantageously, some of the strain gauges of the second electrical bridge circuit are arranged corresponding to the first measurement area, for example the first notch, whereas the second It may be proposed that another strain gauge of the electrical bridge circuit is arranged corresponding to the second measurement region, for example the second notch.

  In a special configuration, a protective device is provided that protects one or more measuring sensors against contamination and / or damage. This protective device may for example have a shrink ring or be formed as a shrink ring. It may be proposed that at least one measuring sensor is arranged below the protective sealing material.

  In a particularly advantageous configuration of the forklift according to the invention, the bending force measuring device is formed as an axle, in particular a rear axle and / or a steering axle, and / or as a component of an axle suspension. In a special configuration, the bending force measuring device is formed as a support with an integrally molded, in particular coaxial swing journal, for suspension on a vehicle, in particular a vehicle frame.

It is a perspective view of the center axle body of the axle of the forklift according to the present invention. It is a side view of the bending force measuring apparatus formed as a support body of a center axle body. It is a figure which shows roughly the possible corresponding | compatible example of arrangement | positioning of the measurement sensor to a measurement circuit.

  In the following, embodiments for carrying out the invention will be described in detail with reference to the drawings.

  FIG. 1 shows a center axle body 1 of a rear (steering) axle formed as a steering axle of a four-wheel forklift according to the present invention. Basically, the present invention can also be used in a three-wheel forklift. A deflection force measuring device 2 formed as a support is fixed to the center axle body 1, for example, a screw. This bending force measuring device 2 constitutes a constituent element of the center axle body 1 and a constituent element of the axle as a structural constituent member. In other words, the bending force measuring device 2 not only works for detecting the axle load, but also constitutes an axle component disposed in the power flow, as will be described further. By this axle component, the axle is swingably suspended on a vehicle frame (for example, a counterweight as a part of the vehicle frame) of the forklift that is not shown in the drawing.

  For the above-mentioned purpose, the bending force measuring device 2 (also see FIG. 2) formed as a support has two coaxial journals P1, P2 formed integrally. Both swing journals P1, P2 are spaced apart from each other in the longitudinal direction of the vehicle, and are provided for engaging an elastic axle bearing coupled to the vehicle frame.

  Adjacent to each swing journal P1; P2, the bending force measuring device 2 is machined with one horizontal notch Q1; Q2 extending horizontally. Each of the lateral cutouts Q1; Q2 is divided vertically by measurement sections 2a, 2b; 2c, 2d formed as bending beams of the bending force measuring device 2.

The axle force F _A is introduced into the bending force measuring device 2 between both lateral notches Q1, Q2 in the axial direction. The swing journal P1, P2 is the supporting force _{F R} of the vehicle frame acts. Accordingly, the measuring sections 2a, 2b, 2c, 2d formed as a deflecting beam are subjected to a bending load and deformed (slightly) with a corresponding load.

  This amount of deformation caused by compression and expansion of the edge of the surface of the measuring sections 2a, 2b, 2c, 2d is advantageously measured in the measuring sections 2a, 2b, 2c, 2d inside the transverse notches Q1, Q2. Measured by a sensor, in particular a DMS (strain gauge), arranged on the inner surface of In this case, the installation of DMS at the transition (rounded) between the measuring sections 2a, 2b, 2c, 2d and the vertical wall of the lateral notch has proved particularly suitable.

  Of course, alternatively or additionally, it is also possible to attach the DMS to the outer surface of the measuring sections 2a, 2b, 2c, 2d outside the lateral notches Q1, Q2. Furthermore, in the specified use cases, it is sufficient to measure the deformation amount only in some measurement sections instead of all the measurement sections 2a, 2b, 2c, 2d, and to detect the bending force and thus the axle load based on this. It can be. However, the axle load can be detected very accurately by measuring in a larger number of measuring sections. This is because the disturbing force and moment can be calculated.

  Of course, it is also possible to measure the deflection force at another suitable location on the axle and for this purpose the structural component of the axle can be formed in whole or in part as a deflection force measuring device. In this way, for example, it is possible to detect the bending force acting on the steerable steering knuckle that is pivotally attached to the axial end of the center axle body 1. In this case, a measuring section arranged between the steering knuckle pin and the wheel hub support means in the axial direction is formed on the steering knuckle as a deflecting beam.

  FIG. 3 shows a configuration having a first measurement circuit 3 and a second measurement circuit 4. Furthermore, the drawing schematically shows a corresponding arrangement example of the measurement sensors M1, M2, M3, M4 with respect to both measurement circuits 3, 4. This corresponding arrangement allows a particularly reliable measurement of the axle load (which cannot be sufficiently deteriorated by lateral and torsional forces). The measurement sensors M1, M2 formed as strain gauges are arranged in the lateral cutout Q1, whereas the other measurement sensors M3, M4 also formed as strain gauges are in the other lateral cutout Q2. Is placed inside. The first measurement circuit 3 receives the measurement signals of the measurement sensors M1 and M4 disposed in mutually different lateral cutouts Q1 and Q2, whereas the second measurement circuit 4 has different lateral directions. The measurement signals of the measurement sensors M2 and M3 arranged in the notches Q1 and Q2 are received. The drawing schematically illustrates the measurement assembly. Advantageously, another measuring sensor connected in the same manner to the measuring circuits 3, 4 may be provided in the lateral cutouts Q1, Q2.

  The present invention has been described in conjunction with a particular configuration. However, it will be appreciated that changes and modifications can be effected without departing from the scope of protection of the claims.

1 center axle body, 2 bending force measuring device, 2a, 2b, 2c, 2d the measuring section, 3 a first measurement circuit, 4 a second measuring circuit, _{F A} axle force, _{F R} supporting force, M1, M2, M3 , M4 measuring sensor, P1, P2 swing journal, Q1, Q2 lateral notch

Claims (32)

  In a forklift equipped with a force measuring device, the force measuring device is formed as a bending force measuring device, and additionally, at least partially formed as a travel mechanism component, a force measuring device comprising: Forklift equipped.   The forklift according to claim 1, wherein the bending force measuring device has a measurement section, and the amount of deformation caused by the bending load can be measured in the measurement section.   The forklift according to claim 1 or 2, wherein the bending force measuring device has at least one elastically deflectable element.   4. A forklift according to claim 3, wherein the elastically deflectable element comprises a parallelogram guide.   5. A forklift according to claim 3 or 4, wherein the elastically deflectable element is formed as a double deflectable beam.   6. The bending force measuring apparatus according to claim 3, wherein the bending force measuring device has at least one measuring sensor, and the measuring sensor can measure the amount of bending of at least one elastically deflectable element. A forklift according to item 1.   The forklift according to any one of claims 3 to 6, wherein the bending force measuring device has a plurality of measuring sensors, in particular 16 measuring sensors.   8. The forklift according to claim 7, wherein the measurement signals of the plurality of measurement sensors are compared with each other and / or superimposed on each other for the detection of the bending force.   Multiple measurements in such a way that the signal components of the lateral force, which are detected simultaneously in each case without affecting the overall deflection of the individual measurement signals, are eliminated from each other and / or can be removed by computation with each other. 9. A forklift according to claim 7 or 8, wherein the sensors are arranged and / or connected to each other.   The plurality of measurement sensors are arranged and / or are mutually arranged such that the temperature-dependent dependence of the individual measurement signals of the plurality of measurement sensors is sufficiently eliminated from each other at least in a predetermined temperature range. The forklift according to any one of claims 7 to 9, which is connected.   11. A forklift according to any one of claims 7 to 10, wherein a plurality of measurement sensors are arranged to generate redundant measurement signals and / or are connected to each other.   At least one measuring sensor (for example a strain gauge) is provided in the symmetrical plane of the elastically deformable element, and the redundant measuring sensor is arranged in a plane parallel to both sides of the symmetrical plane (for example divided) The forklift according to any one of claims 7 to 11.   The forklift according to any one of claims 1 to 12, wherein an electronic processing unit is provided for receiving a measurement signal of one measurement sensor or measurement signals of a plurality of measurement sensors.   14. A forklift according to claim 13, wherein the processing unit is adapted to detect the bending force from the individual measurement signals.   15. A temperature measuring device is provided, and the processing unit is adapted to correct measurement errors due to temperature of individual measurement signals and / or detected bending forces. Forklift.   The forklift according to any one of claims 13 to 15, further comprising a memory unit in which correction parameters for different temperatures are filed.   The forklift according to any one of claims 6 to 16, wherein the at least one measurement sensor has a strain gauge.   18. A forklift according to any one of claims 6 to 17, wherein at least one measuring sensor is arranged inside the bending force measuring device.   19. A forklift according to any one of claims 6 to 18, wherein at least one measuring sensor is arranged in a lateral notch of the bending force measuring device.   7. The bending force measuring device has a plurality of notches, in which at least one measuring sensor, in particular two measuring sensors, in particular four measuring sensors, are respectively arranged in the notches. The forklift according to any one of items 19 to 19.   The measurement signal of one measurement sensor arranged corresponding to one measurement section, for example arranged in one notch, is arranged corresponding to the other measurement section, for example the other arranged in the other notch Can be compared with the measurement signal of one measurement sensor and / or the processing unit is arranged corresponding to one measurement section, for example one measurement sensor arranged in one notch, 21. A forklift according to any one of claims 6 to 20, adapted to be compared with a measurement signal of the other measurement sensor arranged corresponding to the measurement section, for example arranged in the other notch.   22. A forklift according to any one of claims 6 to 21, wherein the measuring sensor is formed as a strain gauge, which is a component of an electrical bridge circuit, in particular a Wheatstone measuring bridge.   Some of the bridge circuit strain gauges are placed in one notch of the flexure force measuring device and another strain gauge of the bridge circuit is placed in the other notch of the flexure force measuring device. The forklift according to claim 22.   The measurement sensor is formed as a strain gauge, some of which are components of the first electrical bridge circuit, and another strain gauge is the configuration of the second electrical bridge circuit. The forklift according to any one of claims 6 to 23, which is an element.   25. A forklift according to any one of the preceding claims, wherein a protective device is provided to protect one or more measuring sensors against contamination and / or damage.   26. A forklift according to claim 25, wherein the protective device comprises a shrink ring.   27. A forklift according to any one of the preceding claims, wherein at least one measuring sensor is arranged below the protective sealing material.   28. A forklift according to any one of claims 1 to 27, wherein the deflectable element is formed as a deflecting beam.   29. A forklift according to any one of the preceding claims, wherein the bending force measuring device is formed as an axle, in particular a rear axle and / or a steering axle, and / or as a component of an axle suspension.   30. A device according to claim 1, wherein the deflection force measuring device is formed as a support with a monolithic, in particular coaxial swing journal, for suspension on a vehicle, in particular a vehicle frame. The forklift described in the item.   Adjacent to each oscillating journal, one lateral cutout is machined, in particular a horizontally extending horizontal cutout, which is divided into upper and lower parts by measuring sections. The forklift according to claim 30.   The forklift according to any one of claims 1 to 31, wherein the bending force measuring device is formed for detecting an axle load.

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