AU2022228140A1

AU2022228140A1 - Temperature sensor device, undercarriage assembly and temperature monitoring system of at least one undercarriage component

Info

Publication number: AU2022228140A1
Application number: AU2022228140A
Authority: AU
Inventors: Nicolas Moretti
Original assignee: Taltractor Itm SpA
Current assignee: Taltractor Itm SpA
Priority date: 2021-09-08
Filing date: 2022-09-08
Publication date: 2023-03-23
Also published as: IT202100023210A1

Abstract

A temperature sensor device configured to be reversibly fixed to an outer surface of an undercarriage component, wherein the sensor device comprises a container having a hollow body, a magnetic element attached 5 to a bottom wall of the hollow body, externally to the container, wherein the magnetic element is configured to reversibly magnetically fix the container to an outer surface of an undercarriage component, as a contact surface; a temperature transducer housed inside the cavity and configured to output electrical signals indicative of temperature; an 10 electronic sensor module housed inside the cavity of the container hollow body, operatively connected to the temperature transducer and configured to receive the electrical signals indicative of temperature from the temperature transducer, the electronic module comprising a sensor wireless transmitter configured to generate measurement signals 15 wirelessly, and an electrical power source housed inside the cavity and operatively connected to the electronic sensor module. The invention further relates to an undercarriage assembly comprising a temperature sensor device and a temperature monitoring system of at least one undercarriage component using said sensor device. 20 Figure 3 1/8 1 L 10 1'I14 27i 20___ ---F---24,25 24 ( 22 FIGI1 116 L 55 10 20 FIG 2

Description

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Temperature sensor device, undercarriage assembly and temperature monitoring system of at least one undercarriage component DESCRIPTION The present invention refers to a temperature sensor device. In particular, the sensor device is for monitoring the temperature of an undercarriage component. The present invention also refers to a temperature monitoring system and an undercarriage assembly which comprises at least one such temperature sensor device. The tracked undercarriages are typically used in operating machines such as earthmoving machines, mining machines, demolition machines and the like, to allow the machine to be able to move on an often uneven ground or with poor grip. A tracked undercarriage typically comprises two chain assemblies spaced apart and arranged parallel to each other and configured to receive a driving torque and transfer it to the ground. Each undercarriage comprises a plurality of components that usually comprise a closed loop chain on a drive wheel and an idler wheel (also called idler) operatively connected to a tensioning assembly. The undercarriage further comprises, between the drive wheel and the idler wheel, a plurality of rollers that are configured to guide the chain during its motion. The rollers usually include one or more upper rollers and a plurality of lower rollers (track rollers). The chain usually comprises a plurality of joints that are rotatably connected to each other at respective ends. Each joint comprises a pair of links facing each other. The links of each joint are usually interconnected with one another by pins and bushings. Each pin is usually inserted into holes provided on the links to connect two links together. The bushings are usually placed radially outside the pins to distance the links of the joints from one another, to protect the pins from the external environment and to mesh the drive wheel.

Soles are usually mounted on the joints which, being in direct contact with the ground, have the task of discharging the traction to the ground and of increasing the contact surface between machine and ground. The undercarriage is usually subjected to very harsh operating conditions that can derive from the overall weight of the machine, the high powers transferred from the engine of the machine to the ground and/or from the conformation and composition of the ground on which the machine must operate. The undercarriage components are therefore subjected to high mechanical stress that can cause damage and wear of the components themselves. For example, the lower or upper rollers are made of metal, typically steel, and "bushings" are usually placed radially outside the shaft of the rollers to reduce friction between moving parts. A bushing arranged internally to the roller can rotate integrally with the roller around a shaft or be fixed with respect to the rotating roller. The bushings are typically lubricated to reduce friction between the contact surfaces of the bushing and roller or bushing and shaft. Inadequate lubrication increases friction, leading to wear of the bushing, the thickness of which gradually thins, up to the point of causing a damage to the underlying shaft and/or to other elements of the roller, thus requiring a machine stop in order to be able to carry out restoration or replacement operations. An indication of inadequate lubrication is the heat generated in the bushing and roller/pin or more generally within an operating undercarriage component, due to increased friction between the contact surfaces. A further undercarriage component that can be subject to temperature rise is the final drive, which is a mechanical apparatus designed for the transmission of motion from the motor to the tracks of the undercarriage. The final drive usually has multiple gears in its inside that are immersed in the lubricating oil, resulting in heat developed by friction during the operation of the tracked undercarriage. More generally, the mechanical stresses of varying magnitude to which the undercarriage components are subjected induce a significant increase in the inner temperature, which might reach critical values that can affect the functional integrity of these components, especially during the movement operations of the earth-moving machines that use the tracked undercarriage. In order to ensure a correct operation of the vehicle and at the same time minimise the number of machine downtimes, it would be important to be able to know in real time the temperature reached in the undercarriage components, for example in the roller assemblies, such as lower or upper rollers, in the drive wheel, idler roller and/or in the final drive, pins or bushings. One approach is to integrate sensors into undercarriage components or between the undercarriage components to measure magnitudes such as lubricating oil temperature or component wear. Publication US 2013/0255354 Al discloses a monitoring device in an undercarriage assembly having a roller assembly that includes a fixed roller component (shaft or housing) and a bushing. The monitoring device has two sensors which detect two distinct physical characteristics of the bushing. In one example, the monitoring device has a temperature sensor used to determine the state of the lubricant inside the roller assembly. The monitoring device may include a temperature sensor and a Hall effect sensor that produce output signals. The document mentions that output signals are transferred via a wireless transmitter to a computer or the data are accessible via a port that connects to the monitoring device. Publication WO 2021/105938 Al of the same Applicant, discloses a monitoring system of at least one physical magnitude that comprises the temperature, the system comprising a sensor device housed in a housing seat inside a respective undercarriage component and configured to detect the temperature within the undercarriage component. The Applicant noted that the sensors integrated in the undercarriage components are difficult for operators to access and therefore cannot be easily replaced or transferred from one component to another as required. The Applicant also noted that the positioning of sensors in the undercarriage components or between the undercarriage components often requires the provision of special cavities that can structurally weaken the components. In addition, the Applicant noted that some undercarriage components may not be suitable for housing sensors internally, e.g. due to their small sizes or due to their conformation. Furthermore, the Applicant noted that the integration of sensors into a large number of undercarriage components would lead to a significant cost burden. In this context, the Applicant has considered that if a temperature monitoring device capable of monitoring the temperature of an undercarriage component from a position easily accessible to an operator and capable of being easily connected and disconnected to/from the component itself were provided, the noted drawbacks would be avoided. The present invention concerns, in a first aspect thereof, a temperature sensor device configured to be reversibly fixed to an outer surface of an undercarriage component, the sensor device comprising: - a container comprising a hollow body having a cavity, wherein the hollow body comprises a container bottom wall having an inner surface facing said cavity and an opposite outer surface; - a magnetic element fixed to the container bottom wall, externally to the container, so as to form a base for the temperature sensor device, the magnetic element being configured to magnetically reversibly fix the sensor device to an outer surface of an undercarriage component, as a contact surface; - a temperature transducer housed inside the cavity and configured to output electrical signals indicative of temperature; - a sensor electronic module housed inside the cavity of the container hollow body, operatively connected to the temperature transducer and configured to receive the electrical signals indicative of temperature from the temperature transducer, the electronic module comprising a sensor wireless transmitter configured to generate measurement signals wirelessly based on the electrical signals received from the temperature transducer, the wireless measurement signals including data indicative of temperature, and - an electrical power source housed inside the cavity and operatively connected to the electronic sensor module. The contact surface of the outer surface of the undercarriage component on which the sensor device is reversibly arranged is made of a ferromagnetic material, e.g. steel, a material commonly used for the manufacture of undercarriage components. The container hollow body comprises at least one side wall which extends from the container bottom wall along a longitudinal axis orthogonal to the container bottom wall. The at least one side wall defines an upper opening of the hollow body. The upper opening of the hollow body may be closed by a lid or, as described below, by a filler that partially or completely fills the cavity of the container hollow body. Preferably, the magnetic element is attached to and in contact with the outer surface of the bottom wall of the container hollow body. Preferably, the magnetic element has a magnetic element upper surface and an opposite magnetic element lower surface, the magnetic element surfaces being planar. Preferably, the magnetic element upper surface is coupled to the container via the outer surface of the container bottom wall. The container bottom wall is preferably in direct contact with the magnetic element upper surface. Preferably, the planar extent of the magnetic element upper and lower surfaces is substantially the same as that of the container bottom wall. Preferably, the magnetic element lower surface is reversibly attached to the outer surface of the undercarriage component. Thus, in use, the magnetic element comes into direct contact with the outer surface of the undercarriage component by being fixed thereto in a reversible manner. Since in a typical use the temperature monitoring of one or more undercarriage components occurs during the movement of the tracked undercarriage and thus with the undercarriage components in motion, a stable adhesion between the magnetic element and the outer surface of the undercarriage component is generally required during the monitoring. The adhesion capacity by magnetic attachment can be expressed by the tensile force. Preferably, the magnetic element is designed so as to have a tensile force greater than 1 kg, for example from 1 to 70 kg. Preferably, the magnetic element is designed to have a tensile force from 20 to 70 kg. In the present description and claims, reference will be made to a magnetic element which may be an elementary component of a part or an assembly. In the second case and according to one example, the magnetic element comprises or consists of a neodymium permanent magnet inserted into a steel capsule. The magnetic element, being usually made of a metal, typically has a thermal conductivity that allows a good thermal conduction between the contact surface of the undercarriage component and the container that houses the temperature transducer, the heat transfer depending mainly on the material of which the container is made, in particular the hollow body, and the magnet and on the axial thicknesses of the container bottom wall and of the magnet. Preferably, the magnetic element has an axial thickness from 3 to 10 mm. In embodiments in accordance with the present invention, the magnetic element may be irreversibly attached to the container bottom wall, for example glued to the bottom wall, or reversibly attached. In the case where the magnetic element is glued to the bottom wall of the hollow body, a glue or other suitable adhesive may be used for gluing the materials of the respective surfaces. Preferably, the magnetic element is attached to the container bottom wall reversibly through one or more removable fixing elements. Preferably, the fixing element is a screw. In one embodiment in accordance with the present invention, the magnetic element and the container bottom wall comprise a respective through-hole, each hole extending in the axial direction of the sensor device, namely in a direction substantially perpendicular with respect to the upper and lower surfaces of the magnetic element. The through-hole of the magnetic element and the through-hole of the container bottom wall are aligned with each other so as to be able to accommodate the one or more fixing elements. Preferably, the fixing element has a length that is substantially equal to the sum of the axial thicknesses of the magnetic element and of the container bottom wall so as not to protrude or at least not to protrude much with respect to the inner surface of the container bottom wall. In a non-limiting way, the through-hole of the magnetic element is countersunk near its lower surface to accommodate the head of the screw. This prevents the screw from protruding from the lower surface of the magnetic element so as to decrease the distance between the contact surface of the magnetic element and the outer surface of the undercarriage component and to improve the tensile force between the magnet and the surface of the undercarriage component and the thermal conduction, in the axial direction, between the elements of the sensor device. Preferably, the screw and more generally the fixing element is made of metal material, for example steel. The power source is preferably a battery, for example a button battery. Preferably, the electronic sensor module comprises a printed circuit board. The printed circuit board has a predominantly planar extension and has a lower side facing the container bottom wall and an opposite upper side. The upper side of the printed circuit board faces upward in an operating position of the sensor device, when in contact with an outer surface of the undercarriage component. The sensor wireless transmitter is mounted on one of the two sides of the printed circuit board.

Preferably, the electronic module comprises a sensor electronic processor mounted on one of the two sides of the printed circuit board and configured to receive the electrical signals indicative of temperature from the temperature transducer and to transmit said signals to the sensor wireless transmitter for generating corresponding wireless sensor measurement signals. In the usual ways, the sensor wireless transmitter is connected to an antenna for transmitting the wireless sensor measurement signals. The antenna, which may be an on-chip planar antenna, is preferably mounted on the upper side of the printed circuit board. The sensor wireless transmitter is configured to generate radio frequency (RF) measurement signals. Preferably, the sensor wireless transmitter is configured to generate short-range RF signals, for example with a range of action (maximum signal extension) from about 5 metres to about 50 metres. Preferably, the wireless signals are Bluetooth signals, more preferably Bluetooth Low Energy (BLE). In one embodiment in accordance with the invention, the electronic module is a PCBA (Printed Circuit Board Assembly). The sensor electronic processor is typically a microprocessor, associated with a memory and configured to receive the electrical signals indicative of temperature coming from the temperature transducer, typically through circuit components, which in this case are integrated into the printed circuit board. The microprocessor is configured to store the received measurement signals and then to send them to the sensor wireless transmitter for wireless transmission of the measurement signals by means of an antenna. In a first embodiment of the sensor device in accordance with the present invention, the temperature transducer is arranged on the inner surface of the container bottom wall. Preferably, the temperature transducer is arranged in direct contact with the inner surface of the container bottom wall.

Preferably, according to a first embodiment of the sensor device: - the electrical power source is a battery arranged above the temperature transducer, - the printed circuit board is arranged above the battery and is electrically connected thereto, and - the temperature transducer is electrically connected to the printed circuit board. The arrangement of the components for the generation of wireless signals for the detection of the temperature one above the other allows a reduction in the size of the container that accommodates these components and therefore of the sensor device. Preferably, the printed circuit board is arranged above the battery at a distance therefrom along the longitudinal direction of the sensor device. Preferably, the battery comprises a first and second power terminal that electrically connect the battery with the electronic module and the temperature transducer is electrically connected to the electronic module. The temperature transducer may be connected to the printed circuit board via electrical wires connected to an electrical connector that is connected to the board, for example welded on a circuit board track of one of the sides of the board. According to a second embodiment of the temperature sensor device: - the power source is a battery which is arranged on the container bottom wall; - the printed circuit board is arranged above the battery and is electrically connected thereto, and - the temperature transducer is mounted on one of the two sides of the printed circuit board so that it is electrically connected to the printed circuit board. Preferably, the battery is arranged in direct contact with the inner surface of the container bottom wall. In an example in accordance with this second embodiment, the temperature transducer is a separate component, mounted on the printed circuit board, and operatively connected to the sensor electronic processor. Alternatively, the temperature transducer is part of a microchip comprising the sensor electronic processor, e.g. a microprocessor, the microchip being electrically connected to the printed circuit board. In this case, the temperature transducer may be a transducer integrated into a PCBA. Preferably, the container has a cylindrical hollow body. A continuous side wall defines the cavity and a circular upper opening of the hollow cylindrical body. Preferably, the hollow body comprises a cylindrical wall which extends from the base wall around the cavity. The container hollow body comprises an upper opening arranged on an opposite side with respect to the bottom wall. Preferably, the cylindrical wall is made as one piece with the base wall. Preferably, in the examples in accordance with the invention wherein the container has a cylindrical shape, the magnetic element preferably has a discoidal shape. However, the shape of the container having hollow body is not to be understood as limiting and the hollow body may have for example a parallelepiped shape. The container of the sensor device is made of metal, for example steel or aluminium. In many embodiments it is preferable that the container is made of aluminium or an aluminium alloy with relatively high thermal conductivity, typically at least 200 W-m-1-K-1. In examples consistent with the invention, the container hollow body is made of aluminium or an aluminium alloy. In examples consistent with the invention, the temperature transducer is an NTC (Negative Temperature Coefficient) thermal probe or a PTC (Positive Temperature Coefficient) thermal probe. Preferably, the cavity of the container hollow body is at least partially filled with an electrically insulating filler in which the temperature transducer, the electrical power source and the electronic sensor module are embedded. Preferably, the filler fills the cavity substantially completely up to the upper opening of the container hollow body. Preferably, in order to improve heat transfer between the contact surface of the undercarriage component and the temperature transducer, in the embodiments in which the temperature transducer is integrated into the electronic sensor module, the filler is a polymeric material, preferably an epoxy resin, with a thermal conductivity greater than the thermal conductivity of the air. Preferably, in the embodiment in which the temperature transducer is arranged on the inner surface of the container bottom wall, the filler is a polymeric material with a conductivity lower than or equal to that of the air. In a second aspect, the present invention relates to an undercarriage assembly, comprising: - an undercarriage component having a ferromagnetic outer surface comprising a contact surface, and - a temperature sensor device in accordance with the first aspect of the present invention, wherein the sensor device is reversibly fixed to said contact surface by means of said magnetic element. In a third aspect, the present invention concerns a temperature monitoring system of at least one undercarriage component, the system comprising: - at least one temperature sensor device according to the first aspect of the present invention, wherein the at least one temperature sensor device is reversibly fixed to an outer surface of an undercarriage component as a contact surface for the temperature sensor device, wherein the data indicative of temperature included in the sensor wireless measurement signals include at least one temperature value, the at least one temperature value being a value of outer surface temperature associated with said undercarriage component, - a wireless transceiver remote with respect to the at least one temperature sensor device configured to receive said wireless sensor measurement signals and to generate corresponding wireless measurement signals which include said at least one outer surface temperature value, and - a processing unit remote with respect to the at least one temperature sensor device and configured to communicate with said remote wireless transceiver and to receive, from the remote wireless transceiver, said at least one outer surface temperature value associated with said undercarriage component. The remote processing unit is or comprises an electronic processor, which in some configurations may be part of a computer. Preferably, the remote processing unit is configured to provide information indicative of the at least one outer surface temperature value. For example, the remote processing unit is configured to generate a notification that comprises information identifying the at least one measured outer surface temperature value. The notification can be rendered to a user in various manners, e.g. through a view on a display in communication with the remote processing unit. The notification or more generally the information indicative of the temperature values measured by the temperature sensor device may be provided to a user when the measured temperature values are such as to define an anomalous condition of the monitored undercarriage component. The anomalous condition can be defined by the passing of a temperature threshold value measured on the undercarriage component. Preferably and in accordance with a first embodiment of the monitoring system in accordance with the present invention, the remote processing unit is configured to: - store said at least one outer surface temperature value, Ts, received from the remote wireless transceiver; - determine whether the at least one outer surface temperature value received is greater than a predefined temperature threshold value associated with said undercarriage component, and - if the received outer surface temperature value is greater than the predefined threshold value, generate information indicative that the predefined temperature threshold value associated with the undercarriage component associated with the at least one sensor device has been exceeded. Preferably and in accordance with a variant of the first embodiment of the monitoring system in accordance with the present invention, the remote processing unit is configured to: - store said at least one outer surface temperature value, Ts; - receive and store a room temperature value, TA; - calculate a temperature relative difference value between the values of the outer surface temperature and the room temperature, (Ts TA);

- determine whether the temperature relative difference value (Ts-TA) is greater than a relative difference threshold value ATth; - if the calculated relative difference value (Ts-TA) is greater than the relative difference threshold value ATth, determine that the undercarriage component is in an anomalous condition, and - generate information indicative that the undercarriage component is in an anomalous condition. Preferably and in accordance with a further embodiment of the monitoring system in accordance with the present invention, the system is configured to monitor a plurality N of undercarriage components of an undercarriage, wherein a respective sensor device is reversibly fixed to an outer surface of each undercarriage component of the plurality N of undercarriage components. The remote processing unit is configured to: - receive N outer surface temperature values from the plurality of N sensor devices;

- store the plurality of N outer surface temperature values, wherein each outer surface temperature value is stored in association with a respective sensor device identifier of the plurality of sensor devices; - compare each outer surface temperature value of the plurality of N stored outer surface temperature values with the remaining (N-1) values of the plurality by calculating (N-1) values of relative differences between the considered temperature value and each of the remaining (N-1) temperature values; - if a value of the plurality of N outer surface temperature values has a relative difference value greater than a relative difference threshold value, determine that the undercarriage component associated with the sensor device identifier that is associated with that outer surface temperature value is in an anomalous condition, and - generate information indicative that this undercarriage component is in an anomalous condition. Preferably, the undercarriage components of the plurality N of undercarriage components are analogous components, i.e. having similar or equal structure and functionality. For example, the plurality of components is a plurality of lower rollers or a plurality of upper rollers. Preferably, the monitoring system comprises a gateway comprising: a remote gateway wireless transceiver configured to communicate with the sensor wireless transmitter of at least one temperature sensor device; a gateway processing unit in communication with said remote gateway wireless transceiver and configured to receive measurement signals from said remote wireless transceiver, and a wireless access point operatively connected to the gateway processing unit and configured to receive the measurement signals from the remote wireless transceiver and to generate corresponding wireless measurement signals, the wireless access point acting as an entry point for accessing data representative of temperature, which are detected by the at least one sensor device, wherein the remote processing unit is configured to communicate with the wireless access point and to receive the measurement signals from the wireless access point that correspond to the measurement signals of the remote wireless transceiver. Alternatively, the remote processing unit corresponds to the gateway processing unit included in the gateway. Preferably, the wireless access point is configured to generate medium range wireless signals, in particular with a range of action from about 20 metres to about 500 metres, for example Wi-Fi radio signals. Further features and advantages of the invention will result better from the following description of embodiments, made with reference to the accompanying figures, provided for illustrative purposes only and, therefore not limiting, in which: - Figure 1 shows a perspective view of a temperature detection sensor device of an undercarriage component in accordance with an embodiment according to the present invention; - Figure 2 shows a perspective view of the sensor device of Fig. 1 from a different angle; - Figure 3 shows a sectional view of a sensor device according to a first embodiment in accordance with the present invention; - Figure 4 shows a schematic view of components of the sensor device of Fig. 3; - Figure 5 shows an exploded view of the sensor device of Fig. 3; - Figure 6 shows a sectional view of a sensor device according to a second embodiment in accordance with the present invention; - Figure 7 shows a schematic view of components of the sensor of Fig. 6; - Figure 8 shows an exploded view of the sensor device of Fig. 6; - Figure 9 shows a view of a first undercarriage assembly comprising the aforesaid sensor device; - Figure 10 shows a view of a second undercarriage assembly comprising the aforesaid sensor device;

- Figure 11A shows a view of a third undercarriage assembly comprising the aforesaid sensor device; - Figure 11B shows a view according to a different angle of the undercarriage assembly of Figure 11A; - Figure 12 shows a schematic view of a temperature monitoring system of an undercarriage component comprising the aforesaid sensor device. The same elements or elements with similar functions have been indicated with the same reference numbers in the different drawings. A temperature detection sensor device of an undercarriage component, in accordance with embodiments of the present invention, is illustrated in the accompanying figures, where it is indicated by the numerical reference 1. The sensor device 1 comprises a container 10, which comprises or consists of a hollow body 11 having a longitudinal axis L and comprising a bottom wall 12 (indicated in Figs. 3 and 6) and a side wall 14. The side wall 14 extends from the container bottom wall 12 along the longitudinal axis L. The hollow body 11 has a cavity 15, delimited by the container bottom wall 12 and by the side wall 14. The hollow body 11 is configured to partially wrap and protect the content of the cavity 15, which will be described here below. In the embodiment illustrated in the figures, the container 10 and in particular the hollow body 11 has a substantially cylindrical shape. The side wall 14 is preferably cylindrical and can be made as one piece with the container bottom wall 12. The container bottom wall 12 has an extension predominantly planar and orthogonal to the longitudinal axis L. The container bottom wall 12 preferably has a discoidal shape. An opening 16 for accessing the cavity 15 is defined by the hollow body 11 in a position axially opposite the container bottom wall 12 with respect to the cavity 15. The opening 16 is defined by the side wall 14.

The container bottom wall 12 has a thickness measured in the axial direction (i.e. axial thickness), i.e. parallel to the longitudinal axis L. The container bottom wall 12 has an inner surface 17 facing the cavity 15 and an outer surface 18 facing away from the inner surface 17. The cavity 15 has, in some examples in accordance with the present invention, a volume from 5 to 50 cm 3 , for example 16 cm 3

. Preferably, the axial thickness of the bottom wall 12 is from 1 to 6 mm, for example 4 mm. Preferably, the container hollow body 11 is made of a metal material. Preferably, the container hollow body 11 is made of aluminium or an aluminium alloy, materials that usually have a high thermal conductivity. A magnetic element 20 is fixed to the container bottom wall 12 of the container 10, externally thereto, so as to form a base for the sensor device 1. The magnetic element 20 comprises a permanent magnet, preferably made entirely of a magnetized material, such as, for example, a neodymium magnet. For example, the magnetic element comprises or consists of a neodymium permanent magnet, e.g. made of a boron-iron neodymium alloy, inserted into a steel capsule. In the embodiments illustrated in the figures, the magnetic element 20 has a substantially discoidal shape. Preferably, the planar extension of the magnetic element 20, measured in a plane orthogonal to the longitudinal axis L, substantially coincides with that of the container bottom wall 12. The magnetic element 20 has an upper surface 21, facing the outer surface 18 of the container bottom wall 12 and preferably arranged in direct contact therewith (also indicated in Figs. 5 and 8). The magnetic element 20 also has a lower surface 22, opposite the upper surface 21. The lower surface 21 is planar and configured to come into direct contact with an outer surface of an undercarriage component 100, which will be described in more detail below. Preferably, the magnetic element 20 has a thickness measured in the axial direction from 3 to 10 mm, for example 7 mm. Preferably, the magnetic element 20 is fixed to the container bottom wall 12 reversibly through one or more removable fixing elements 24. The one or more fixing elements 24 may comprise, for example, a screw. In the embodiments illustrated in the figures, the container bottom wall 12 comprises a hole 13 which extends in the axial direction, preferably arranged at a geometric centre of the container bottom wall 12. The hole 13 of the container bottom wall 12 is, in the illustrated example, a threaded through-hole. Preferably, the magnetic element 20 comprises a through-hole 23, extending in an axial direction, aligned with the hole 13 of the container bottom wall 12. In the example of the figures, the container 10 and the magnetic element 12 are fixed to each other by means of a screw 24, as a fixing element. The screw 24 has a threaded stem 26 that engages the thread of the hole 13 of the container bottom wall 12. Preferably, the hole 23 of the magnetic element 20 comprises a countersunk seat 23a at the lower surface 22. The screw 24 has a countersunk head 27 housed in the countersunk seat 23a of the hole 21 of the magnetic element 20. Preferably, the head 27 is flush with the lower surface 22 of the magnetic element 20 or is sunk into the countersunk seat 23a, so as not to protrude with respect to the lower surface 22. Preferably, the screw 24 has an axial extension substantially equal to the sum of the thicknesses of the container bottom wall 12 and of the magnetic element 20, so as not to protrude with respect to the inner surface 17 of the container bottom wall 12. Preferably, the screw 24 or, more generally, the fixing element, is made of a metal material, e.g. steel. In another possible alternative embodiment not illustrated in the figures, the container 10 and the magnetic element 20 are fixed to each other irreversibly, for example by gluing the outer surface 18 of the container bottom wall 12 to the upper surface 21 of the magnetic element, for example by means of a cyan acrylic or epoxy glue. In this case, the hole 13 of the container bottom wall 12, the hole 23 of the magnetic element 20 and the fixing elements 24 may be omitted. The magnetic element 20 is configured to magnetically reversibly fix the container 10 to a contact surface 105 of an undercarriage component 100 made of a ferromagnetic material or comprising ferromagnetic material elements, such as for example ferritic steels. The magnetic element 20 has a magnetic tensile force sufficient to hold the sensor device 1 in a fixed position on the undercarriage component 100 when the undercarriage component 100 is subjected to stresses that are typical of its operating life. Preferably, the total magnetic moment of the magnetic element 20 is greater than 1 kg, more preferably greater than 20 kg. In one example, the magnetic element 20 is designed to have a tensile force equal to 52 kg. When the magnetic element 20 is magnetically fixed to an outer surface of an undercarriage component 100, a thermal "bridge" is created between the latter and the hollow body cavity 15 thanks to the thermal conductivity of the magnetic element 20, of the container bottom wall 12 and, optionally, of the fixing element 24. The sensor device 1 comprises a temperature transducer, an electronic sensor module and an electrical power source 40, housed in the cavity 15 of the hollow body 11. Preferably, the electrical power source 40 is a battery 41 and the following description will refer to a battery. In a first embodiment in accordance with the present invention, schematically illustrated in Figs. 3, 4 and 5, the container hollow body 11 houses a temperature transducer 50. Preferably, the temperature transducer 50 is arranged in direct contact with the container bottom wall 12 of the container 10, in particular with the inner surface 17 of the bottom wall 12 or in contact with the bottom wall 12 of the container 10 through a thermally conductive adhesive paste. Preferably, the temperature transducer 50 has a detecting portion 52 that is preferably placed in direct contact with the inner surface 17 of the container bottom wall 12, optionally fixed by means of the thermally conductive adhesive paste. In one example in accordance with the present invention, the temperature transducer 50 is a thermal probe that can be of the passive type. For example, the thermal probe may be an NTC (negative temperature coefficient) probe having a negative temperature coefficient that causes a decrease in resistance as the temperature increases, or the thermal probe may be a PTC (positive temperature coefficient) probe having a positive temperature coefficient that causes an increase in resistance as the temperature increases. Alternatively, the thermal probe 50 may be an active type probe. In the example of the figures, the thermal probe 50 has a discoidal shape. The temperature transducer 50 is preferably offset from the position of the hole 13 in the container bottom wall 12 so as not to engage the fixing element 24 and/or allow a good thermal contact between transducer and bottom wall. Preferably, the temperature transducer 50 is designed to measure temperatures up to about 2000 C. In the embodiment of Figs. 3-5, the temperature sensor is physically separated from the sensor electronic module 30. In this first embodiment, the battery 41 is arranged above the temperature transducer 50 and the sensor electronic module 30 is arranged above the battery 41. In other sensor words, the battery 41 is axially interposed between the temperature transducer 50 and the sensor electronic module 30. The temperature transducer 50 may be fixed to the battery 41, for example by welding or glues. The sensor electronic module 30 is schematically illustrated in Fig. 4. The sensor electronic module 30 comprises a printed circuit board 31. The printed circuit board 31 has a predominantly planar extension and is arranged substantially parallel to the inner surface 17 of the bottom wall

12. In addition, the printed circuit board 31 has an upper side 32 facing the opening 16 and a lower side 33 facing the container bottom wall 12. The upper side 32 of the printed circuit board 31 faces upwards in an operating position of the sensor device 1. Preferably, the sensor electronic module 30 is a PCBA (Printed Circuit Board Assembly), i.e. a printed circuit board (PCB) on which electrical and/or electronic components are welded. The PCBA 31 may be single layer or double-layer. If the printed circuit board 31 is single-layer, all electronic components welded on the printed circuit board 31, described below, are welded on the upper side 32. If the printed circuit board 31 is double-layer, the electronic components welded on the printed circuit board 31 may be welded on both the upper side 32 and on the lower side 33, unless otherwise indicated. In a non-limiting way, in the present embodiment and in a second embodiment described below, the PCBA components are mounted on the upper side 32 of the board. The temperature transducer 50 is electrically connected to the electronic module 30 and in particular to the printed circuit board 31 through electrical wires 54 connected to an electrical connector 53 that is connected to the board, for example welded on a circuit track of one of the sides of the board (Figs. 4, 5). The electrical connector 53 electrically connects the temperature transducer 50 with the sensor electronic module 30 and, through it, with the battery 41, which electrically powers the temperature transducer 50. As is generally known, in the event that the thermal probe 50 is of the passive type, the electrical connector 53 comprises two electrical cables through which the electronic module 30 measures the temperature, for example by measuring the resistance in the NTC or PTC type probe. In per se known ways, in the event that the thermal probe 50 is of the active type, the electrical connector comprises two power cables and at least one signal cable through which the temperature transducer 50 sends electrical signals indicative of the measured temperature. The electronic module 30 comprises a sensor electronic processor 35. The sensor electronic processor 35 is mounted on the printed circuit board 31, for example on the upper side 32 of the printed circuit board 31. The sensor electronic processor 35 comprises a microprocessor associated with a memory and can be integrated into the PCBA of the electronic module 30. The electronic module 30 may further comprise circuitry components 36 connected with the temperature transducer 50 for managing electrical signals in input from the electrical connector 53 of the temperature transducer, which may comprise a conditioning circuit of analogue signals coming from the temperature transducer, a possible amplifier for converting the input signals into an analogue or digital voltage or current output signal, and an analogue-digital A/D signal converter. The signals coming from the temperature transducer 50 and possibly processed by the circuit components 36 are transmitted to the electronic processor 35. The electronic module 30 further comprises a sensor wireless transmitter 37 operatively connected to the sensor electronic processor 35 and configured to generate radio frequency (RF) wireless measurement signals. Preferably, the wireless measurement signals generated by the sensor wireless transmitter 37 are short-range radio signals, more preferably signals transmitted in broadcast mode without connection. Preferably, the sensor wireless transmitter 37 is a sensor wireless transceiver. In the present context, short-range radio signals typically indicate radio signals with a range of action from about 5 metres to about 20 metres. Preferably, the wireless signals emitted by the sensor wireless transmitter 37 are Bluetooth signals, more preferably Bluetooth Low Energy (BLE). The sensor wireless transmitter 37 is connected to an antenna 38 for transmitting the wireless measurement signals. The antenna 38, which may be a on-chip planar antenna, is preferably mounted on the upper side 32 of the printed circuit board 31. The sensor wireless transmitter 37 and the electronic processor 35 are mounted on one side of the printed circuit board 31, in the example illustrated on the upper side 32 of the printed circuit board 31. The battery 41 comprises power terminals 34, for example a first positive terminal and a second negative terminal, connected to the printed circuit board 31. The power terminals 34 are configured to power the electrical and/or electronic components of the sensor electronic module 30 and in general the electrical/electronic components of the sensor device 1 described below. The battery 41 illustrated in the figures is a button battery. In the illustrated example, a respective terminal 34 is welded on the upper surface and on the lower surface of the button battery 41. Preferably, the first and second power terminal 34 are rigid metal elements. Preferably, the first and the second power terminal 34 extend, at least for a portion thereof, in a vertical direction which substantially corresponds to the longitudinal direction L of the sensor device 1 when in the position of use. For example, the first and second power terminal are L-shaped and the connection with the printed circuit board is made by connecting the ends of the vertical portion of each terminal to the board. In this way, the printed circuit board is arranged at a distance from the battery 41 along the longitudinal direction L of the sensor device. In a second embodiment in accordance with the present invention, schematically illustrated in Figs. 6, 7 and 8, a temperature transducer 58 is part of an electronic module 30a. The electronic module 30a comprises a printed circuit board 31 of the type illustrated with reference to the first embodiment. Compared to the first embodiment, the electronic module 30a comprises the temperature transducer. The temperature transducer 58 is preferably integrated on the electronic circuit board 31, e.g. PCB or PCBA. For example, the temperature transducer 58 is directly welded on the printed circuit board 31, for example on its upper side 32 or alternatively its lower side 33. The temperature transducer 58 may be an NTC or PTC probe, of the type described above. The electrical signals coming from the temperature transducer 58 and indicative of the measured temperature, possibly processed by the circuit components 36, are transmitted to a sensor electronic processor 35. In a further embodiment (not illustrated in Fig. 7), the temperature transducer is integrated into the sensor electronic processor 35. In the latter case, the temperature transducer is included in a microchip comprising the sensor electronic processor 35, the microchip being mounted on the printed circuit board 31. In the embodiments in which the temperature transducer is integrated into the electronic module, preferably the battery is arranged directly on the inner surface 17 of the container bottom wall 12. Figures 6 and 8 show respectively a sectional view and an exploded view of a sensor device 1 in accordance with the second embodiment and with the variant thereof (temperature transducer integrated in the microchip of the electronic processor). The battery 41, preferably a button battery, comprises first and second power terminal 34 connected to the electronic module 30a and in particular to the printed circuit board 31 for powering the electrical and/or electronic components. For further possible implementation details related to the battery, reference is made to the description above. The temperature transducer of the embodiments in accordance with the present invention is configured to measure a temperature and output electrical signals indicative of such temperature. In the first embodiment of the sensor device (Figs. 3-5), the temperature measured by the temperature transducer 50 substantially corresponds to the temperature of the container bottom wall 12, in the context of a measurement error considered normally acceptable in this technical sector. In the second embodiment of the sensor device (Figs. 6-8), the temperature measured by the temperature transducer, both as a separate electrical component 58 and as a component integrated into a microchip comprising the electronic processor, is substantially a temperature internal to the cavity 15 of the hollow body 11, in the context of a measurement error considered normally acceptable in this technical sector. The temperature transducers integrated into the microprocessor of the printed circuit board typically have a sensitivity and detection accuracy lower than a separate temperature transducer 50 or 58. However, the Applicant noted that in some applications, the use of a temperature transducer integrated into the PCBA microprocessor may reduce the costs of the sensor device. The temperature measured by the temperature transducer is, with sufficient approximation, a measurement of the temperature of the outer surface 105 of an undercarriage component 100 (Figs. 9-11). Operationally, the sensor electronic processor 35 may be configured to activate the measurement by the temperature transducer at a pre-set time rate that defines a sampling interval. For example, the sensor electronic processor 35 may be configured to command a temperature measurement every 1 or 2 minutes. The electrical signals outputted by the temperature transducer are transmitted to the sensor electronic processor 35, for example through the circuit components 36 of the printed circuit board 31 or internal to the microchip of the electronic processor. The electronic processor 35 stores the electrical signals indicative of temperature to then sends them to the sensor wireless transmitter 37 which generates signals wirelessly in order to transmit them through the antenna 38. In per se known ways, the sensor electronic processor 35 processes the input electrical signals indicative of temperature to transform them into digital data packets representative of the measured temperature(s) and sends the data packets to the sensor wireless transmitter 37, which transmits them through the antenna 38. Preferably, the cavity 15 of the container 10 is at least partially, more preferably entirely, filled with an electrically insulating filler 55, visible in Fig. 2 and not indicated in Figs. 3 and 6. The filler 55 is made of polymeric material, preferably a resin, for example an epoxy resin. The filler 55 incorporates the electrical and electronic components of the sensor device 1 and holds them fixed in position in the cavity 15. In other words, the electronic module 30, the battery 40 and the transducer 50 are embedded in the filler 55. The presence of a filler 55 can dampen or cushion the stresses transmitted to the sensor device 1 by the undercarriage component 100, so as to protect the electrical and/or electronic components thereof. Preferably, the filler 55 is configured to protect the electronic components in a waterproof manner. Preferably, the filler 55 fills the cavity 15 substantially completely up to the upper opening 16 of the container hollow body. In embodiments that provide for the temperature transducer integrated in the printed circuit board 31 and therefore not in contact with the container bottom wall 12, preferably the filler has a higher thermal conductivity than that of the air. For example, the filler is an epoxy resin with a thermal conductivity of 0.5 W/mK greater than the thermal conductivity of the air, equal to about 0.02 W/mK. In this way, the filler 55 is able to more effectively propagate heat within the cavity 15. In the first embodiment (Figs. 3-5) in which the temperature transducer is in contact with the bottom wall 12 of the container 11, it is preferable that the filler, if present, has a thermal conductivity equal to or lower than that of the air to avoid possible thermal dispersions inside the container 11. In use, a sensor 1 as described above is magnetically fixed to a contact surface 105 of an undercarriage component 100. Figures 9, 10, 11A-11B illustrate examples of undercarriage component 100. In order to allow the reversible magnetic coupling of the device 1, the undercarriage component 100 is at least partially made of ferromagnetic materials, such as for example ferritic steels. The contact surface 105 is an outer surface portion of the undercarriage component 100, i.e. a surface accessible to an operator for the arrangement of one or more temperature sensors 1 on said outer surface.

In general, the outer surface of an undercarriage component can be considered as a plurality of outer surfaces (e.g., roller parts, flanges, pins protruding outside, support arms, etc.), which also depend on the type of undercarriage component. In the present context, where not more specifically defined, outer surface means any outer surface portion of the undercarriage component suitable for fixing the temperature sensor device. The undercarriage component on which a temperature sensor device is reversibly attached in accordance with the embodiments of the present invention described herein is referred to as undercarriage assembly. Figure 9 illustrates an example of an undercarriage assembly in which the undercarriage component 100 is a track roller 101 of an undercarriage. In this example, the contact surface 105 on which the sensor device 1 is reversibly fixed is arranged at an end of a central pin 102a of the track roller. Figure 10 illustrates an example of an undercarriage assembly in which the undercarriage component 100 is a final drive 102 of an undercarriage. In the illustrated embodiment, the contact surface 105 on which the sensor device 1 is reversibly fixed is a portion of a side face of the final drive 102, facing the outside of the undercarriage. Figures 11A and 11B illustrate an example of an undercarriage assembly in which the undercarriage component 100 is an idler wheel 103 of an undercarriage. In the illustrated example, the contact surface 105 on which the sensor device 1 is fixed is arranged at a support arm 103a (bracket) of the idler wheel 103. According to an aspect, the present invention also concerns a temperature monitoring system of at least one undercarriage component, on which one or more sensor devices 1 are magnetically reversibly fixed as described above. In an embodiment, illustrated in Fig. 12, the monitoring system comprises a gateway 60 in wireless communication with one or more sensor devices 1, in the figure a plurality of sensor devices, which are reversibly attached to one or more undercarriage components. In one example, the plurality of sensor devices 1 is reversibly fixed to a respective plurality of undercarriage components (not shown). The gateway60isanetworkgateway comprising a gateway wireless transceiver 61 configured to receive radio frequency (RF) signals from the sensor devices 1, in particular from respective sensor wireless transmitters. The signals transmitted by the sensor device and received by the gateway wireless transceiver 61 are preferably short- or medium range signals, such as Bluetooth signals, for example BLE signals. For example, the RF signals periodically transmitted by the one or more sensor devices 1. The wireless measurement signals emitted by each temperature sensor device 1 include data indicative of temperature of the respective sensor. The gateway 60 comprises a gateway processing unit 62 operatively connected to the gateway wireless transceiver 61 and configured to receive the measurement signals from the gateway wireless transceiver 61. Preferably, the measurement signals transmitted by each temperature sensor device 1 include a respective sensor device identifier. The wireless sensor measurement signals include data representative of temperature that are stored in the gateway processing unit 62 in association with the respective sensor device identifiers 1. The gateway processing unit 62, for example a microprocessor, typically associated with a non-volatile memory, on which the wireless measurement signals received from the gateway wireless transceiver 61 and optionally data representative of temperature included in the measurement signals, in association with the sensor device identifiers, are stored. The gateway 60 further comprises a wireless access point (WAP) 64 operatively connected to the gateway processing unit 62, which is configured to transmit the measurement signals received from the gateway transceiver 61 to the wireless access point 64.

The WAP 64 is configured to act as an entry point to the measurement signal data that are stored in the gateway processing unit 62. Preferably, the wireless access point 64 is configured to generate medium-range wireless signals, in particular with a range of action from about 20 metres to about 500 metres, for example Wi-Fi radio signals, for example in accordance with the standard IEEE 802.11 protocols. As is generally known, the wireless access point 64 typically comprises a processor for receiving the measurement signals from the gateway processing unit 62 and for storing them in a memory associated with the processor and a Wi-Fi transceiver configured to receive the measurement signals from the processor and transmit them wirelessly via a Wi-Fi antenna. In this way, any client terminal 81 provided with Wi-Fi connectivity, for example a smartphone, tablet or PC, can connect to the WAP 64, which acts as a hotspot, by means of a known-type authentication procedure and request access to the data relating to the measurement signals stored in the gateway processing unit 62 of the gateway 60. Preferably, the wireless access point 64 may be configured to operate simultaneously both as access point and as Wi-Fi station. When it operates as a Wi-Fi station, the access point 64 is configured to transmit the data stored in the gateway processing unit 62 to another wireless access point external to the gateway (not shown in the figure).

A user in relative proximity but remotely from the vehicle can thus monitor the data relating to the temperature measurements and then obtain information on the operating conditions of the undercarriage components. The client terminal 81 is preferably in communication with a server/computer 85 remote with respect to the gateway 60 which comprises a remote processing unit (not indicated) which is configured to receive the data relating to the temperature measurements detected by the sensor devices 1 and optionally to process such data.

Preferably, the gateway 60 further comprises a mobile connection module

67, e.g., a cellular modem, operatively connected to the gateway processing unit 62 for transmitting measurement signals received from a gateway wireless transceiver 61 to a server or terminals remotely over a mobile telecommunication network 68. The measurement signals transmitted by the mobile connection module 67 may be received from a server/computer 83 remotely and for example viewed by an operator or otherwise accessible on a remote terminal. The server/computer 83 remote with respect to the gateway 60 comprises a processing unit (not indicated) which is configured to receive the data relating to the temperature measurements detected by the sensor devices 1 and optionally to process such data. The gateway 60 is arranged in the vicinity of the tracked undercarriage, at a distance therefrom such as to allow the gateway 60 to receive the measurement signals, wherein on a plurality of undercarriage components the respective sensor devices 1 are reversibly fixed. The gateway 60 may be arranged within a vehicle, e.g., an earth-moving machine, mounted on the tracked undercarriage. In per se known ways, the gateway 60 may further comprise a CAN (Controller Area Network) controller 70 connected to a CAN on-board communication network 69, also referred to as a CAN-BUS network that uses a standardized communication protocol (CAN protocol) that uses a serial data transfer for communication between microcontrollers and electronic devices mounted in the vehicle and that detect vehicle's parameters, typically via CAN network cables 72. In one example in accordance with the present invention, the gateway processing unit 62 is operatively connected to the CAN on-board network 69 for transmitting data representative of temperature measured by the temperature sensor devices 1. The CAN-BUS network is connected to one or more on-board displays and the data representative of temperature sent by the CAN controller 69 may be viewed by an operator on board the vehicle. The gateway 60 is preferably implemented on a printed circuit board (PCB). In particular, the gateway wireless transceiver 61, the gateway processing unit 62, the wireless access point 64 and, if present, the mobile connection module 67 and the CAN controller 70, are mounted on a single PCB. The electronic components of the gateway 60 are powered by a power module 73, for example a battery, also preferably mounted on the same PCB. Advantageously, the monitoring system allows the management of the measurement signals of one or a plurality of sensor devices in the tracked vehicle in real time both remotely and in the vicinity of the sensor devices, by means of a single wireless connection with the respective sensor devices. In examples in accordance with an aspect of the present invention and described in more detail below, the temperature monitoring system does not use a gateway for communicating the data related to temperature measured by the sensor devices 1. In particular, the one or more sensor devices 1 communicate "directly" with any client terminal 80 provided with Bluetooth, Wi-Fi connectivity, for example a smartphone, tablet or PC, which comprises a wireless transceiver remote with respect to the sensor wireless transmitter 37 and which is located in the vicinity of the temperature sensor device(s) 1. In general, different manners, which are known per se, of using the information regarding the temperature associated with the monitored undercarriage components are possible. Preferably, the data related to temperature measured by the one or more temperature sensor devices are processed by a remote processing unit. In the present context, with remote processing unit it is meant a processing unit remote with respect to the one or more temperature sensor devices, and in direct or indirect communication, with the one or more sensor devices. "Remote" means that the processing unit or other device is arranged at a distance from the sensor device, wherein the distance can vary from a relatively short distance, for example using short- or medium-range RF signals (Bluetooth, Wi-Fi, etc.), to very long distances, for example using signals from a cellular telecommunication network. The remote processing unit is configured to receive data indicative of temperature included in the wireless measurement signals emitted by the at least one sensor device and to process such data indicative of temperature. Preferably, the remote processing unit is further configured to generate a notification that includes indicative information relating to the outer surface temperature of the undercarriage component associated with the sensor device. Since during temperature detection the temperature sensor device is arranged in contact with an outer surface of an undercarriage component, the temperature measurement is thus relative to said outer surface. In most cases of interest, heat is generated in an inner zone of the undercarriage component, in particular in the zones where the component parts are in contact and/or in relative motion with each other, for example near the pin or the bushing of a roller component. The "critical" inner zone of the undercarriage component is therefore positioned at a certain distance from the contact surface where the sensor device is positioned. Due to the distance and the temperature difference between the parts of an undercarriage component, there is a temperature difference between the inner zone and the outer surface in contact with the device. In general, this difference is a function of the geometric dimensions of the undercarriage component, of the constituent material, of the mass of the component and of the thermal properties of the materials. In some applications within the scope of the present invention, it may be preferable to obtain an estimate of the inner temperature of the undercarriage component starting from the measurement of the outer temperature by means of the sensor device in accordance with the present invention. In general, heat dissipation occurs owing to three phenomena, conduction, convection and irradiation. The heat Q generated by friction inside the undercarriage component is dissipated to the outside following the laws of these three phenomena.

In a stationary regime, assuming that the inner temperature Ti is higher than the room temperature TA, a heat dissipation inside the undercarriage component towards the outside is assumed. As a first approximation, it is possible to simplify heat dissipation inside the undercarriage component, wherein: T1 is the inner temperature in K Ts is the outer surface temperature in K TA is room temperature in K Rev is the convection thermal resistance in K/W Rcd is the conduction thermal resistance in K/W, and Q is the power to be dissipated in W. The conduction resistance Rcd depends on the geometric parameters of the component and on the thermal conductivity of the material, whereas the convection resistance Rey depends on the outdoor atmospheric conditions near the undercarriage component and in particular on the surface of the undercarriage component exposed to dissipation and on a convective coefficient. In the first approximation, the conduction resistance of the magnet and of the metal container that houses the detection components Ts can therefore be ignored. If the contribution of the room temperature is ignored (for example in the case of relatively low external temperatures), the inner temperature value T1 is proportional to the respective outer surface temperature value TE, according to the relationship:

Ti=C-Ts (1)

wherein C is a coefficient greater than 1. The coefficient C is calculated based on the values of convection thermal resistance and conduction thermal resistance. For example, the value of the coefficient C can be calculated according to the following relationship

C= d+Rcv (2) Rev

wherein Rcd isthe thermal resistance equivalent to the conduction of the undercarriage component 100 and wherein Rev is the thermal resistance equivalent to the convection of the undercarriage component 100. A better approximation also takes into consideration the contribution of the room temperature and the relationship between the inner temperature of the component and the measured surface temperature is given by the relationship

TI=C-Ts +(1-C) TA (3)

where TA is the atmospheric temperature near sensor device 1, referred to below as room temperature. The value of the coefficient C can, for example, be determined empirically, by constructing temperature curves for each undercarriage component. The room temperature can be measured, for example, by means of a thermometer that can be mounted on the gateway and that measures the room temperature of the moving machine having the tracked undercarriage or near it. Monitoring the temperature of one or more undercarriage components that uses an estimate of the inner temperature starting from the temperature of the outer surface of a component can, in some practical cases, however, be complex to be defined and hence to be implemented. The Applicant considered that monitoring the temperature of the outer surface of the undercarriage component can provide, in many cases of interest, a reliable indication of the wear and/or malfunction of the component. For example, an anomalous rise in the temperature of the outer surface of an undercarriage component taken individually or considered in relation to the temperatures measured in other undercarriage components provides an indication of malfunction of the monitored component. Preferably, the processing of the data indicative of the temperature measured by the sensor devices 1 is performed by a remote processing unit (electronic processor or microprocessor). In one example, the RF measurement signals received from the client terminal 80 in communication may be processed in a remote processing unit of a computer 84 (e.g., a remote server) in communication with the client terminal 80, e.g., over the mobile network. For example, a user of the client terminal 80, but could also be the client terminal 81, if the system includes the gateway 60, may use a dedicated application that can be downloaded from the client terminal. The user, once the application is launched and the client terminal 80 is configured to receive the RF signals from one or more sensor devices, may enter a command to initiate the processing of the RF signals that include data indicative of the temperature of an outer surface of an undercarriage component, wherein such processing is performed by the computer 84 or 85. The remote processing unit may thus be part of a computer that comprises, in the usual ways, memory areas accessible to that processing unit. The computer is in remote with respect to the plurality of sensor devices 1, for example it is a remote server/computer 83, 84, or 85. Alternatively, the remote processing unit is included in a client terminal 80, 81, if it is provided with processing capacity and/or software programs or applications that are capable of implementing the processing of the data received from the sensor devices. In a further example according to an aspect of the present invention, the remote processing unit is part of the gateway 60 and corresponds to the gateway processing unit 61. In this example, the gateway processing unit 61 is configured to communicate with the remote wireless transceiver (WAP) 64 and to receive at least outer surface temperature values associated with one or more undercarriage components 100 and to process the acquired temperature values to determine whether an undercarriage component has an anomalous temperature and is therefore in an anomalous condition, according to one or more of the manners described below. The remote processing unit is configured to receive data indicative of temperature measured by each sensor device 1 of the plurality of sensor devices as outer surface temperature values Ts, each temperature value Ts being uniquely associated with a sensor device identifier 1. The outer surface temperature values associated with a respective sensor device and therefore with a respective undercarriage component, can be made accessible to a user in various manners, generally known. In accordance with a preferred embodiment according to the present invention, a threshold temperature value, Tth, associated with an undercarriage component for which the temperature is to be monitored is defined. If the temperature detected by the sensor device arranged on such undercarriage component exceeds the predefined threshold value Tth, the remote processing unit is configured to generate information indicative that the predefined temperature threshold value has been exceeded. For example, the monitoring computer or other computer connected thereto, through the execution of a program, may be configured to generate a notification that comprises information identifying the outer surface temperatures associated with respective undercarriage components. The notification may be viewed on a display operatively connected to the computer which comprises the remote processing unit or transmitted as a message viewable or otherwise usable on another electronic device in communication with the computer and to which the user has access. The values of temperature or of relative temperature differences greater than a predefined threshold value can generate an alarm or be highlighted in a display of the temperature monitoring results. Alternatively, the notification generated by the remote processing unit is a notification or alarm signal indicative that the threshold temperature value has been exceeded. In per se known ways, the notification or alarm signal may be made accessible to a user, for example as an audio signal or light signal viewable on a dashboard of the tracked vehicle. In accordance with a further preferred embodiment according to the present invention, the determination, by means of the temperature sensor device, that an undercarriage component has an anomalous temperature, in particular a high temperature with respect to the working temperatures of the component, i.e. indicative of an anomalous condition of the undercarriage component, takes into account the room temperature, TA, i.e. the temperature of the outdoor air in which the undercarriage component operates. The room temperature is measured by means of a thermometer or a temperature transducer, not in contact with the outer surface of the undercarriage component whose temperature is to be monitored. Thel temperature TA is measured in the vicinity of the undercarriage component, in particular at a close distance with respect to the undercarriage component, for example by means of a temperature transducer arranged on an outer surface of the undercarriage, the undercarriage surface not undergoing significant heating during operation of the vehicle or in the vehicle itself. Alternatively, the room temperature can be measured externally to the undercarriage or the vehicle itself. The room temperature TA may be measured at a time rate while monitoring the outer surface temperature Ts of the undercarriage component or at the beginning of the temperature monitoring step. In the latter case, the temperature TA can also be measured with a thermometer. The measured room temperature value can be entered by an operator, using a data input device (keyboard, touch screen, etc.) operatively connected to the remote processing unit. In the embodiment that includes the gateway for receiving and transmitting the wireless signals from one or more temperature sensors in accordance with the invention, the gateway 60 preferably comprises a temperature transducer for measuring the room temperature (not shown in Fig. 12). The room temperature detection transducer is operatively connected to the gateway processing unit 62 that receives the room temperature measurement for subsequent data processing. In a different embodiment, the temperature transducer for detecting the room temperature is coupled to an electronic module which comprises a wireless transmitter for the communication of the transducer with the remote processing unit implementing the monitoring. In one embodiment in accordance with the present invention, the remote processing unit is configured to: - receive and store an outer surface temperature value Ts measured by temperature sensor device 1; - receive and store a room temperature value, TA; - calculate a relative temperature difference value between the values Ts and TA, (Ts-TA); - determine whether the relative temperature difference value (Ts-TA) is greater than a relative difference threshold value ATth; - if the calculated relative difference value (Ts-TA) is greater than the relative difference threshold value ATth, determine that the undercarriage component is in an anomalous condition, and - generate information indicative that the undercarriage component is in an anomalous condition, in particular the undercarriage component is associated with a high temperature that is considered critical for the component. The information indicative of the anomalous condition is made available to a user in a per se known manner and exemplified in the previous description. The procedure for detecting an anomalous condition in the working temperature of the undercarriage component in accordance with the steps described above is preferably repeated, for example by performing temperature measurements at predefined time intervals. In this embodiment, Ts>TA is assumed because the measurement is typically performed during operation of the monitored undercarriage component. In a further embodiment of the present invention, the temperature monitoring system is a monitoring system of a plurality of undercarriage components, wherein a respective temperature sensor device 1 is arranged on each undercarriage component of the plurality, specifically a respective sensor device is magnetically reversibly fixed to an outer surface of each component of the plurality. Preferably, the undercarriage components of the plurality of undercarriage components are analogous components, i.e. having similar or equal structure and functionality. For example, the plurality of components is a plurality of lower rollers or a plurality of upper rollers. In such an embodiment, the identification of the undercarriage components whose outer surface temperature is considered anomalous is performed automatically by the remote processing unit. In this embodiment, the processing unit is configured to: - receive N outer surface temperature values from the plurality of N sensor devices 1; - store the plurality of N outer surface temperature values, wherein each outer surface temperature value is stored in association with a respective sensor device identifier of the plurality of sensor devices 1; - compare each outer surface temperature value of the plurality of N stored outer surface temperature values with the remaining (N-1) values of the plurality by calculating (N-1) values of relative differences between the considered temperature value and each of the remaining (N-1) temperature values, ATi, i= 1,...,(N-1); - if a value of the plurality of N outer surface temperature values associated with the respective sensor device identifiers has a relative difference value greater than a relative difference threshold value in relation to the remaining (N-1) temperature values, determine that the undercarriage component associated with the identifier of sensor device 1 that is associated with said outer surface temperature value is in an anomalous condition, and

- generate information indicative that that undercarriage component 100 is in an anomalous condition. The information indicative of the anomalous condition is made available to a user in a per se known manner and exemplified in the previous description. The procedure of determining an anomalous condition of one or more undercarriage components of a plurality of undercarriage components in accordance with the steps described above is preferably repeated, for example by performing temperature measurements at predefined time intervals. The monitoring of a plurality of undercarriage components by comparison among components is in some applications sufficiently reliable and does not require a measurement of the room temperature and its variations during the measurement time. The person skilled in the art will recognize that it is possible to combine the various characteristics of the embodiments described above to obtain further embodiments, all falling within the scope of the present invention as defined by the subsequent claims.

Claims

CLAIMS 1. A temperature sensor device (1) configured to be reversibly fixed to an outer surface (105) of an undercarriage component (100), the sensor device comprising: - a container (10) comprising a hollow body (11) having a cavity (15), wherein the hollow body comprises a container bottom wall (12) having an inner surface (17) facing said cavity and an opposite outer surface (18); - a magnetic element (20) fixed to the container bottom wall (12), externally to the container (10), so as to form a base for the temperature sensor device (1), the magnetic element (20) being configured to magnetically reversibly fix the sensor device (1) to an outer surface of an undercarriage component (100), as a contact surface (105); - a temperature transducer (50; 58) housed inside the cavity (15) of the container hollow body (11) and configured to output electrical signals indicative of temperature; - a sensor electronic module (30; 30a) housed inside the cavity (15) of the container hollow body (11), operatively connected to the temperature transducer (50; 58) and configured to receive the electrical signals indicative of temperature from the temperature transducer, the electronic module (30; 30a) comprising a sensor wireless transmitter (37) configured to generate measurement signals wirelessly based on the electrical signals received from the temperature transducer (50; 58), the wireless measurement signals including data indicative of temperature, and - an electrical power source (40) housed inside the cavity (15) and operatively connected to the sensor electronic module (30; 30a).
2. The temperature sensor device (1) according to claim 1, wherein the magnetic element (20) has a magnetic element upper surface (21) and an opposite magnetic element lower surface (22), the magnetic element being attached to the container bottom wall (12) via the outer surface

(18) of the bottom wall (12).
3. The temperature sensor device (1) according to claim 1 and 2, wherein the sensor electronic module (30; 30a) comprises a printed circuit board (31) having an upper side and an opposite lower side, the lower side being facing the container bottom wall (12), and wherein the sensor wireless transmitter (37) is mounted on one of the two sides of the printed circuit board (31).
4. The temperature sensor device (1) according to claim 3, wherein the electronic module (30; 30a) comprises a sensor electronic processor (35) mounted on one of the two sides of the printed circuit board (31) and configured to receive the electrical signals indicative of temperature from the temperature transducer (50; 58) and to transmit said signals to the sensor wireless transmitter (37) for generating corresponding wireless sensor measurement signals.
5. The temperature sensor device (1) according to one or more of the preceding claims, wherein the temperature transducer (50) is arranged on the inner surface (17) of the container bottom wall (12).
6. The temperature sensor device according to claim 5, when dependent on one of claims 3 or 4, wherein - the electrical power source (40) is a battery (41) arranged above the temperature transducer (50), - the printed circuit board (31) is arranged above the battery (41) and is electrically connected thereto, and - the temperature transducer (50) is electrically connected to the printed circuit board (41).
7. The temperature sensor device according to any one of the preceding claims, wherein the cavity (15) of the container hollow body (11) is at least partially filled with an electrically insulating filler (55) in which the temperature transducer (50; 58), the electrical power source (40) and the electronic sensor module (30) are embedded.
8. The temperature sensor device according to any of claims 3, 4 or 7, when dependent on claims 3 or 4, wherein - the power source (40) is a battery (41) which is arranged on the container bottom wall (12); - the printed circuit board (31) is arranged above the battery (41) and is electrically connected thereto, and - the temperature transducer (58) is mounted on one of the two sides of the printed circuit board (31) so as to be electrically connected to the printed circuit board (31).
9. The temperature sensor device according to claim 8, when dependent on claim 7, wherein the filler (55) is a polymeric material having a thermal conductivity greater than the thermal conductivity of the air.
10. An undercarriage assembly, comprising: - an undercarriage component (100) having a ferromagnetic outer surface comprising a contact surface (105), and - a temperature sensor device according to any one of the preceding claims 1 to 9, wherein the sensor device is reversibly fixed to said contact surface (105) by means of said magnetic element (20).
11. A temperature monitoring system of at least one undercarriage component (100), the system comprising: - at least one temperature sensor device (1) according to any one of claims 1 to 9, wherein the at least one temperature sensor device (1) is reversibly fixed to an outer surface of an undercarriage component (100) as a contact surface (105) for the temperature sensor device, wherein the data indicative of temperature included in the wireless sensor measurement signals include at least one temperature value, the at least one temperature value being an outer surface value associated with said undercarriage component, - a wireless transceiver (64; 67; 80, 81) remote with respect to the at least one temperature sensor device (1), configured to receive said wireless sensor measurement signals and to generate corresponding wireless measurement signals which include said at least one outer surface temperature value, and - a processing unit (62; 80, 81; 83, 84, 85) remote with respect to the at least one temperature sensor device (1) and configured to communicate with the remote wireless transceiver (64; 67; 80, 81) and to receive said at least one outer surface temperature value associated with said undercarriage component (100).
12. The temperature monitoring system according to claim 11, wherein the remote processing unit (62; 80, 81; 83, 84, 85) is configured to: - store said at least one outer surface temperature value; - determine whether the received at least one outer surface temperature value is greater than a predefined temperature threshold value associated with said undercarriage component (100), and - if so, generate information indicative that the predefined temperature threshold value associated with the undercarriage component (100) associated with the at least one sensor device (1) has been exceeded.
13. The temperature monitoring system according to claim 11, wherein the remote processing unit (62; 80; 83, 84, 85) is configured to: - store said at least one outer surface temperature value, Ts; - receive and store a room temperature value, TA; - calculate a relative temperature difference value between the outer surface temperature and the room temperature values, (Ts-TA); - determine whether the relative temperature difference value (Ts-TA) is greater than a relative difference threshold value, ATth; - if the calculated relative difference value (Ts-TA) is greater than the relative difference threshold value ATth, determine that the undercarriage component (100) is in an anomalous condition, and - generate information indicative that the undercarriage component (100) is in an anomalous condition.
14. The temperature monitoring system according to claim 11, wherein the system is configured to monitor a plurality N of undercarriage components of an undercarriage, wherein a respective sensor device (1) is reversibly fixed to an outer surface of each undercarriage component (100) of the plurality N of undercarriage components, the remote processing unit (62; 80; 83, 84, 85) being configured to: - receive N outer surface temperature values from the plurality of N sensor devices (1); - store the plurality of N outer surface temperature values, wherein each outer surface temperature value is stored in association with a respective sensor device identifier of the plurality of sensor devices (1); - compare each outer surface temperature value of the plurality of N stored outer surface temperature values with the remaining (N-1) values of the plurality by calculating (N-1) values of relative differences between the considered temperature value and each of the remaining (N-1) temperature values; - if a value of the plurality of N outer surface temperature values has a relative difference value greater than a relative difference threshold value, determine that the undercarriage component associated with the sensor device identifier that is associated with that outer surface temperature value is in an anomalous condition, and - generate information indicative that this undercarriage component (100) is in an anomalous condition.
15. The temperature monitoring system according to any one of claims 11 to 14, wherein the system comprises a gateway (60) arranged at a remote location with respect to the at least one sensor device (1), the gateway (60) comprising: - a gateway wireless transceiver (61) configured to communicate with the sensor wireless transmitter (37) of at least one temperature sensor device (1); - a gateway processing unit (62) in communication with said gateway wireless transceiver (61) and configured to receive measurement signals from said remote wireless transceiver (61), and - a wireless access point (64) operatively connected to the gateway processing unit (62) and configured to receive measurement signals from the gateway wireless transceiver (61) and to generate corresponding wireless measurement signals, the wireless access point (64) being said remote wireless transceiver acting as an input point to access data representative of temperature detected by the sensor device (1), wherein the remote processing unit (85) is configured to communicate with the wireless access point (64) and to receive measurement signals from the wireless access point (64) which correspond to the measurement signals of the remote wireless transceiver (61), or the remote processing unit corresponds to the gateway processing unit (62).