Linear guide carriage and linear guide carriage system

Abstract

A linear guide carriage (3) comprises: at least one rolling body (4), via which the linear guide carriage (3) is movable relative to a guide device (2); a recirculation device (5), in which the at least one rolling body (4) is circulatable at least during a relative movement between the linear guide carriage (3) and the guide device (2). To improve wear resistance, the linear guide carriage comprises an electrically-based lubricant sensor (7), which is arranged to detect, on the basis of an electrical property of a lubricant, information relating to a quantity and / or a composition of the lubricant in a detection section (9) in the recirculation device (5).

Description

[0001] Linear guide carriages and linear guide carriage systems

[0002] Field of invention

[0003] The present invention relates to a linear guide carriage and a linear guide carriage system.

[0004] Background of the invention

[0005] In the prior art, for example from DE 10 2018 204 852 A1, a linear guide carriage is movable relative to a guide device. A multitude of rolling elements are located between the linear guide carriage and the guide device. To increase wear resistance and ensure smooth operation, a lubricant reservoir is also provided on the linear guide carriage. The fill level of this lubricant reservoir is monitored so that the lubricant can be replenished as needed. With such linear guide carriages, the amount of lubricant present in the area of ​​the rolling elements is particularly critical. However, monitoring the fill level in the lubricant reservoir is insufficient and allows only limited conclusions about the amount of lubricant present in the area of ​​the rolling elements. Thus, wear can still occur in known linear guide carriages despite monitoring.

[0006] It is therefore an object of the present invention to provide a linear guide carriage with improved detection accuracy of a lubricant condition and improved wear resistance.

[0007] Summary of the invention

[0008] This problem is solved according to the invention by a linear guide carriage according to claim 1.

[0009] According to one aspect, a linear guide carriage is provided for linear movement along a guide device, wherein the linear guide carriage comprises: at least one rolling element, in particular a plurality thereof, about which the linear guide carriage is movable relative to the guide device; and a circulating device in which the at least one rolling element is circulating at least during a relative movement between the linear guide carriage and the guide device.

[0010] In particular, the linear guide carriage differs from the state of the art by having an electrically based lubricant sensor which is arranged to detect information regarding the quantity and / or composition of the lubricant in a detection section in the circulation device based on an electrical property of a lubricant.

[0011] According to this approach, the information regarding the quantity and / or composition of the lubricant is acquired within the circulating device, in which at least one rolling element can circulate. This allows the information to be acquired directly in the area of ​​the rolling elements. As a result, the detection accuracy of the lubricant condition, i.e., the quantity and / or composition, can be improved, enabling timely refilling, which in turn reduces the occurrence of wear phenomena such as pitting and / or galling of the rolling elements.

[0012] Because the lubricant sensor is electro-based, the measurement process can be particularly efficient and compact. In particular, expensive optical elements can be dispensed with.

[0013] In this disclosure, the detection section is a section along the longitudinal extent of the rotating device in which the information is acquired.

[0014] An electrical lubricant sensor is a sensor that uses an electrical property of the lubricant to acquire information. This property can be a material property of the lubricant, specifically its electrical conductivity, resistivity, and / or permittivity. Furthermore, the electrical lubricant sensor can measure an electrical quantity, such as voltage and / or current, based on which it acquires information. The electrical lubricant sensor can incorporate a detection circuit that configures the detection section to function as an electrical circuit element, such as a capacitor with a capacitance or an ohmic resistance.

[0015] The information can be directly related to the quantity and / or composition of the lubricant. However, it can also be related to the quantity and / or composition, in particular an electrical quantity corresponding to the electrical circuit element in the detection circuit formed by the detection section, such as a capacitance value or an ohmic resistance value.

[0016] The detection section can be arranged at least partially, and in particular completely, in a linear section of the circulation device.

[0017] This aspect allows for a simple arrangement of the lubricant sensor and a simple design of the components, since the lubricant sensor can simply be positioned along the linear section. Furthermore, the detection accuracy can be improved due to the less complex flow conditions compared to a curved section.

[0018] Alternatively or additionally, the detection section can be arranged at least partially, in particular completely, outside a load-bearing section of the circulation device, in particular in a return device of the circulation device.

[0019] This also simplifies the placement of the lubricant sensor, as it does not need to be located in the load-bearing section, i.e., in the area of ​​the linear guide carriage facing the guide mechanism. Furthermore, it ensures that lubricant is not displaced from the detection section by the acting loads and can therefore be reliably detected.

[0020] Furthermore, the circulation device can, at least in the detection section, comprise an electrically insulating material, in particular be formed from it.

[0021] This allows for further improvement in detection accuracy due to the electrical insulation. Electrical interference from an electrically conductive circulating device can also be avoided. An electrically insulating material can have a relative permittivity greater than 1. It can, for example, be a plastic, particularly a thermoplastic and / or thermoset. Furthermore, the detection section can extend over a large number of rolling elements. This improves detection accuracy because averaging can be performed across multiple rolling elements. Isolated lubricant accumulations or voids can thus be compensated for.

[0022] For example, the detection section can extend over a length of at least two, three, four or more diameters of the rolling elements.

[0023] The electro-based lubricant sensor can be arranged to capture the information capacitively.

[0024] Thus, the relative electrical permittivity of the lubricant can be used as an electrical property to acquire the information. In other words, an electrical capacitor with a capacitance can be created in the detection section. This allows for a relatively accurate measurement. The lubricant sensor can acquire at least the capacitance value as information, or it can directly acquire information about the quantity and / or composition from this value. The electro-based lubricant sensor can have a detection circuit for acquiring the information, which has two opposing electrodes between which at least one rolling element, and in particular a plurality thereof, is arranged.

[0025] This makes it easy to create the capacitance. Depending on the position of the rolling element during circulation in the detection section, one capacitance or two capacitances can be established, which the detection circuit can connect in series or, more specifically, in parallel. One capacitance can be established if the rolling element contacts one of the electrodes. Conversely, two capacitances can be created, namely between each of the electrodes and the rolling element, if the rolling element does not contact either electrode. The detection circuit can therefore be designed to connect the electrodes in series or in parallel with each other, with the capacitances then adjusting themselves depending on the rolling element's position.

[0026] Within the scope of the invention, the detection circuit can therefore be designed such that, depending on the position of the rolling element in the detection section, a capacitance is established between the electrodes or a capacitance is established between the electrodes and the at least one rolling element.

[0027] In particular, at least one of the electrodes, and in particular both, may have an electrically insulating coating on a side facing the at least one rolling element.

[0028] This ensures reliable capacitance build-up. An electrically insulating coating can suppress ohmic contact between the at least one electrode and the at least one rolling element. This allows for more precise information acquisition, as ohmic influences can be suppressed. The electrically insulating coating can have a relative electrical permittivity greater than 1. It can be made of a plastic, in particular a thermoplastic and / or thermoset, and again, in particular, polyimides.

[0029] Alternatively or additionally, the electrodes can be positioned opposite each other in a direction intersecting the direction of gravity and / or parallel or perpendicular to an axis of rotation of at least one rolling element in the detection section.

[0030] This also prevents contact between at least one rolling element and the electrodes, as the rolling element is not pushed towards the electrodes by gravity. The arrangement parallel to the axis of rotation allows the rolling element to be reliably positioned between the electrodes. Furthermore, the lubricant can reliably fill the space between the electrodes and the rolling element. At least one of the electrodes, and in particular both, can be bonded to the rotating mechanism.

[0031] Accordingly, the attachment of the electrodes can be simplified. An adhesive that attaches at least one electrode to the circulation device can also provide electrical insulation to the outside.

[0032] Furthermore, at least one of the electrodes, in particular both, can be arranged in such a way that it cannot be contacted with the at least one rolling element.

[0033] This also ensures reliable capacitance build-up. A resistive contact between the electrode(s) and the rolling element can be prevented. The arrangement is geometrically designed such that contact is impossible under normal operating conditions. For example, at least one of the electrodes can be positioned in a recess formed by an inner peripheral surface of the rotating device. Alternatively, the inner peripheral surface can be tapered or curved, and the electrode attached to it, in such a way that contact is impossible.

[0034] Alternatively or additionally, the rotating device in the detection section can have larger dimensions than the at least one rolling element, particularly in the direction of the rolling element's axis of rotation in the direction in which the electrodes face each other. This can also prevent ohmic contact.

[0035] The rotating device may have a guide section designed to guide at least one rolling element out of contact with the electrodes.

[0036] Furthermore, the electrically based lubricant sensor can have a detection circuit for capturing the information that electrically contacts at least one rolling element.

[0037] Accordingly, an electrical circuit can be conducted via at least one rolling element, reducing the number of components. Furthermore, electrical quantities such as voltage and / or current can be easily measured. In particular, in the detection circuit, which includes the electrodes, both cases of one or two capacitors can be implemented by electrically contacting the rolling element, depending on the position of the rolling element. The detection circuit can be designed so that the two capacitors or the two electrodes are connected in parallel or in series. If the two electrodes are connected in parallel, the circuit can be easily closed via the electrical contact with the rolling element.

[0038] The detection circuit can further include a resistive element connected in series with the two electrodes. This prevents excessive current during charging of the capacitor(s). The electro-based lubricant sensor can be configured to acquire information based on a charging and / or discharging time.

[0039] Thus, a capacity value can be determined based on the charging / discharging time. This allows for relatively simple implementation, requiring only the measurement of the time it takes for the capacity to be charged to or discharged from a predetermined voltage. The predetermined voltage can be the voltage of the capacity's time constant, i.e., 63.2% of the applied voltage or 63.2% of the capacity's initial voltage.

[0040] Alternatively or additionally, the electro-based lubricant sensor can be designed to acquire information based on sampling a charging and / or discharging curve. This allows a capacity value to be determined based on sampling a charging and / or discharging curve. This enables high detection accuracy, as measurement errors are more easily detected. The voltage and time can be measured at regular intervals. The interval can be a few milliseconds, particularly less than 10 milliseconds.

[0041] Furthermore, the linear guide carriage can include a DC voltage source arranged to supply the electro-based lubricant sensor with direct current.

[0042] This allows the lubricant sensor to be operated with direct current, which simplifies the configuration and acquisition of information.

[0043] Alternatively, the electrically based lubricant sensor can be designed to capture the information ohmically.

[0044] Information regarding the lubricant condition can also be reliably acquired based on this aspect. The configuration can be further simplified. For example, the lubricant sensor can have an electrical contact element in the detection section. The lubricant sensor can be designed to detect the number of contacts with the contact element, for example, within a predetermined time interval or across a predetermined number of rolling elements, and compare this number with a reference value. If the number of contacts is equal to or greater than the reference value, the lubricant sensor can detect that there is insufficient lubricant. Otherwise, it can detect that there is sufficient lubricant.

[0045] According to another aspect, the circulation device can be designed in multiple parts, at least in the detection section, and / or be formed by injection molding. This makes it possible to easily attach the lubricant sensor.

[0046] Furthermore, the linear guide carriage can include an energy harvester configured to provide electrical energy to the linear guide carriage based on the relative motion between the carriage and the guide mechanism. In particular, the linear guide carriage can be configured such that the electrical energy provided by the energy harvester can be used to operate the electrically based lubricant sensor. Accordingly, the linear guide carriage can be used autonomously. The lubricant sensor can therefore be operated without requiring an external energy supply. The energy harvester can generate an alternating current, while the lubricant sensor can still be operated with direct current. For this purpose, an inverter can be provided between the energy harvester and the lubricant sensor.

[0047] Furthermore, the linear guide carriage can have an output unit that can output the information. The output unit can be a wireless communication unit that transmits data related to the information, or a visual or acoustic output unit. Another aspect of the invention relates to a linear guide carriage system comprising a linear guide carriage, wherein the linear guide carriage comprises: at least one rolling element, in particular a plurality thereof, about which the linear guide carriage is movable relative to a guide device; and a circulation device in which the at least one rolling element is circulatory, at least during relative movement between the linear guide carriage and the guide device.The linear guide carriage system can further include an electrically based lubricant sensor which is arranged to detect, based on an electrical property of a lubricant, information regarding a quantity and / or composition of the lubricant in a detection section in the circulation device.

[0048] Thus, the lubricant sensor can also be implemented using physically separate units, whereby part of the lubricant sensor does not need to be located on the linear guide carriage. In particular, if the information is directly related to the quantity and / or composition of the lubricant, the lubricant sensor can include external devices that perform conversions of an electrical quantity such as capacitance into this information.

[0049] Another aspect of the invention relates to a method for operating a linear guide carriage according to one of the aspects mentioned above. In particular, the functional features defined here can be operated according to their function. For example, the lubricant sensor can acquire information during operation based on the charging / discharging time or by scanning the charging / discharging curve. Brief description of the drawings

[0050] The above aspects are explained in more detail in the following description and with reference to the attached figures.

[0051] Fig. 1 shows a perspective view of a linear guide.

[0052] Fig. 2 shows a perspective view of a linear guide carriage in a state reversed compared to Fig. 1.

[0053] Fig. 3 shows the linear guide carriage according to Fig. 2, with one base body removed. Fig. 4 shows a longitudinal section through a circulation device.

[0054] Fig. 5A shows a cross-section through the linear guide carriage in a detection section, with a lubricant sensor arranged on the detection section according to a first embodiment.

[0055] Fig. 5B shows a cross-section through the linear guide carriage in a detection section, with a lubricant sensor arranged on the detection section according to a second embodiment.

[0056] Fig. 5C shows a cross-section through the linear guide carriage in a detection section, with a lubricant sensor arranged on the detection section according to a second embodiment.

[0057] Fig. 6 shows a circuit diagram for Fig. 5B.

[0058] Detailed description of exemplary embodiments

[0059] Figure 1 shows a linear guide 1. The linear guide 1 comprises a guide element 2 extending in a linear guide direction A. The guide element 2, which is designed here as a guide rail, contains a plurality of running surfaces 2a. Two outer running surfaces 2a are provided on one side in a width direction transverse to the guide direction A, while two further outer running surfaces 2a are provided on the other side. The running surfaces 2a are essentially symmetrical with respect to a median plane of the guide element 2 along the guide direction A. In a top view along the guide direction A, two running surfaces 2a on each side with respect to the median plane are arranged in a V-shape in the width direction. The linear guide 1 also includes a linear guide carriage 3, which is also shown in an inverted state in Figure 2.The linear guide carriage 3, in its assembled state, essentially surrounds the guide unit 2 in an inverted U-shape. Two inner raceways 3a are formed on each of the two legs of the U-shape. The raceways 3a face each other in the width direction, forming an insertion space between them into which the guide unit 2 is inserted. The guide unit 2 is inserted into the insertion space such that each raceway 2a interacts with each raceway 3a, with a plurality of rolling elements 4, as shown in Fig. 4, arranged between them.

[0060] The linear guide carriage 3 can move back and forth along the guide direction A relative to the guide device 2 via the rolling elements 4, the rolling elements moving between the running surface 3a and the running surface 2a. The rolling elements can comprise or be formed of an electrically conductive material, for example, steel.

[0061] The linear guide carriage 3 further comprises a circulation device 5 in which the plurality of rolling elements 4 can circulate at least during the relative movement between linear guide carriage 3 and guide device 2.

[0062] The circulation device 5 has a load-bearing section 5a which contains the running surface 3a. In addition to the load-bearing section 5a, the circulation device 5 includes a recirculation device 6. The recirculation device 6 is continuous along the guide direction A to both ends of the load-bearing section 5a, in particular the running surface 3a, and comprises a recirculation tube 6a that extends linearly and parallel to the running surface 3a along the guide direction A. It should be noted that both the load-bearing section 5a and the recirculation tube 6a are linear sections. In other words, the recirculation tube 6a and the load-bearing section 5a define a substantially straight path for the rolling elements 4, in particular a centerline of the recirculation tube 6a and the load-bearing section 5a.

[0063] The return tube 6 is shown, for example, in Figures 3 and 4. The return tube 6a is located further out in the lateral direction (on a side facing away from the guide device 2) with respect to the load-bearing section 5a, and is therefore spaced apart from it. Furthermore, the return device 6 comprises two curved sections 6b (see Figure 4) which connect the load-bearing section 5a and the return tube 6a on both sides in the guide direction A.

[0064] The curved sections 6b are convexly curved in a longitudinal section through the rotating device 5. The rotating device 5 is designed such that the axes of rotation of the rolling elements 4 are aligned parallel over the entire rotation. The entire rotating device 5 extends essentially parallel to the guide direction A.

[0065] As shown in Figures 1 and 2, the linear guide carriage 3 comprises a base body 31 and two end caps 32, which close off the base body 31 at both ends along the guide direction A. The end caps 32 can be designed to be attached to and removed from the base body 31, i.e., as separate elements. The base body 31 is not shown in Figure 3. As shown in Figure 4, the curved sections 6b are each provided in an end cap 32. The curved sections 6b can be tubular and / or provided as separate elements from the end cap.

[0066] The return tube 6a is provided as an element separate from the base body 31. The return tube 6a can be made of or formed from an electrically insulating material, for example, a plastic.

[0067] The return mechanism 6 enables the circulation of the rolling elements 4 from one end of the load-bearing section 5a in the guide direction A to the other end of the load-bearing section 3a in the guide direction A. The return mechanism 6 is designed to guide the circulation and completely surrounds the rolling elements 4. The return mechanism 6 is designed to be fluid-tight. Therefore, lubricant cannot escape from the return mechanism 6.

[0068] Furthermore, a space between the load-bearing section 5a (running surface 3a) and the corresponding running surface 2a of the guide device 2 can be sealed. For this purpose, the linear guide carriage 3 can have a seal at both ends of the load-bearing section 5a.

[0069] In Fig. 3, two return tubes 6a are shown on each side in the width direction, each corresponding to a running surface 3a of the linear guide carriage 3.

[0070] The rolling elements 4 can be, for example, cylindrical rollers or balls. Figure 4 shows an example of rolling elements 4 designed as cylindrical rollers. However, the invention is also applicable to other types of rolling elements.

[0071] Figures 3 and 4 further illustrate the invention in detail. It should be noted that both figures are merely schematic views and do not necessarily correspond.

[0072] According to the invention, an electrically based lubricant sensor 7 is provided. The electrically based lubricant sensor is arranged in particular such that it acquires information regarding the quantity and / or composition of lubricant in the circulating device 5. The lubricant sensor 7 is particularly designed such that the acquisition of the information takes place directly in the circulating device 5.

[0073] As shown in Fig. 4, the lubricant sensor 7 comprises two opposing electrodes 8, with the rolling elements 4 arranged between them and, in particular, spaced apart from each of the electrodes 8. The lubricant sensor 7 can be provided, at least partially, on an inner surface of the circulation device 5. In particular, as shown in Fig. 4, the two electrodes 8 can be arranged on an inner surface of the return tube 6. The electrodes 8 can be bonded in the return tube 6a.

[0074] The electrodes 8 are, for example, strip-shaped or plate-shaped elements.

[0075] Figure 4 further shows the axes of rotation 4a of the rolling elements 4. In the present example, the axes of rotation 4a of the rolling elements 4 are oriented perpendicular to the plane of the drawing. The electrodes 8 face each other perpendicular to the axes of rotation 4a, or are opposite each other in this direction. In this case, the direction in which the electrodes 8 face each other is also a direction intersecting the direction of gravity. If the rolling elements 4 are cylindrical rollers (as in the present example), the electrodes 8 can be arranged so that they face the respective end faces or the respective cylindrical surfaces of the rollers.

[0076] The longitudinal extent of the electrodes 8 defines a detection section 9 along the rotating device 5. The detection section 9 is the section in which an electrical interaction occurs to acquire the information. In the case of electrodes 8 of different lengths, the detection section is defined at least over a region where the electrodes 8 overlap. The electrodes 8 extend over a length corresponding to a plurality of rolling elements 4, in particular diameters thereof. Thus, the electrodes 8 can extend over at least four or five rolling elements 4.

[0077] The detection section 9 is located entirely within the linear section, namely the return tube 6a. In particular, the electrodes 8 are located entirely within the linear section.

[0078] Fig. 5A shows an exemplary arrangement of the electrodes 8 in cross-section with respect to the return tube 6a. In the representation according to Fig. 5A, the arrangement of the electrodes 8 relative to the rolling elements 4 corresponds to the arrangement shown in Fig. 4. In this example, the rolling elements 4 are designed as cylindrical rollers. The electrodes 8 are flat, plate-shaped elements arranged such that they extend parallel to the axes of rotation 4a of the rolling elements 4 (or along the outer surfaces of the respective cylindrical rollers). The dimension of the return tube 6a is larger than the diameter of the rolling elements 4 at least in one direction, in particular in the direction in which the electrodes 8 are opposite each other, and in a direction perpendicular to the axes of rotation 4a. Even though in Fig.Not shown in Fig. 5A, the circulation device 5, in particular the return tube 6a, can have a guide section that guides the rolling elements so that they do not contact the electrodes 8. For example, a V-shaped groove can be provided that prevents the rolling elements 4 from shifting towards the electrodes. In Fig. 5A, the electrodes 8 extend into recesses 61, which are each recessed by a right and left inner peripheral surface of the return tube 6a in a direction perpendicular to the direction in which the electrodes 8 are oriented.

[0079] Fig. 5B shows – as an alternative to the representation in Fig. 5A – an alternative arrangement of the electrodes 8 in the return tube 6a, in which the electrodes 8 are arranged in a recess 61 formed by the lower and upper inner peripheral surfaces of the return tube 6a, respectively. The recess is perpendicular to the direction in which the electrodes 8 face each other. The electrodes 8 are flat, plate-shaped elements arranged such that they extend perpendicular to the axes of rotation 4a of the rolling elements 4 (or parallel to the end faces of the respective cylindrical rollers) and are spaced apart from each other in the direction of the axes of rotation 4a of the rolling elements 4. This prevents contact between the rolling elements 4 and the electrodes 8.Alternatively, the inner peripheral surface of the rotating device can also be curved, in particular more strongly curved than the rolling elements 4, so that contact between electrodes 8 and rolling elements 4 is not possible.

[0080] Fig. 5C shows – as an alternative to the representations in Figs. 5A and 5B – a further alternative arrangement of the electrodes 8 in the return tube 6a. In the representation in Fig. 5C, it is assumed that the rolling elements 4 are designed as spheres. Accordingly, in the present example, the return tube 6a has an internal channel for receiving the rolling elements 4. This channel extends longitudinally along the length of the return tube 6a and has a circular cross-section with an inner diameter larger than the diameter of the rolling elements 4. The return tube 6a according to Fig. 5C has two recessed depressions 61 in the channel intended for receiving the rolling elements 4, each of which serves to receive one of the electrodes 8.In the present example, the electrodes 8 are designed as elements extending longitudinally along the return tube 6a, which are curved in cross-section perpendicular to the longitudinal direction of the return tube 6a (for example, with a radius of curvature larger than the radius of the rolling elements 4). In this way, the shape of the electrodes 8 is adapted to the spherical shape of the rolling elements 4. Furthermore, at least one or both of the electrodes 8 can have an electrically insulating coating, for example, a polyimide film, on the side facing the rolling element 4.

[0081] Fig. 6 shows a circuit diagram for a possible detection circuit according to the invention, exemplified by the arrangement of electrodes 8 shown in Fig. 5B. A DC voltage source can be provided on the linear guide carriage 3. In the diagram of Fig. 6, the detection circuit of the lubricant sensor 7 is designed such that two capacitances are connected in series. In particular, the electrodes 8 are connected in series. According to the laws of electricity, the reciprocal of the total capacitance corresponds to the sum of the reciprocals of the individual capacitances. The voltage can be measured by a voltmeter of the detection circuit between the two electrodes, across the rolling element 4, or it can be measured between the rolling element 4 and each electrode 8. In the latter case, the voltmeter establishes an electrical contact with the rolling element.

[0082] However, it is also conceivable to connect the two capacitors in parallel. In particular, the two electrodes 8 can be connected in parallel. Then one pole of the DC voltage source can be electrically connected to both electrodes 8. The detection circuit can further be designed such that the other pole contacts at least one rolling element 4. In such a parallel connection, the capacitors add up to a total capacitor. The voltage can be measured by a voltmeter of the detection circuit between the two electrodes, across the rolling element 4, or can be measured between the rolling element 4 and each electrode. In any case where the detection circuit establishes electrical contact with the rolling elements, this occurs, in particular, in the direction of gravity, from above or below. Thus, for example, in Fig.6. The top or bottom surface of the inner peripheral area of ​​the return tube shall be provided with an electrically conductive material to which the voltmeter or DC voltage source is connected.

[0083] In the detection circuit, a resistor element R can also be connected in series with the electrodes 8. When the voltage U from the DC voltage source is applied, a current l flows during charging. c via this resistive element R, whereby the voltage Uc builds up at the capacitance.

[0084] In Figures 5A, 5B, and 6, the return pipe 6a is designed in multiple sections, with one division plane running parallel to the direction in which the electrodes 8 are opposite each other. This allows the electrodes 8 to be inserted easily. However, it is also possible to provide a division plane running perpendicular to the direction in which the electrodes 8 are opposite each other (Fig. 5C).

[0085] The linear guide carriage 3 further comprises an energy harvester 10, as indicated in Fig. 3. The energy harvester 10 can provide electrical energy through interaction with at least one rolling element 4. In particular, kinetic and / or potential energy of the rolling elements 4 can be converted into electrical energy.

[0086] For example, the energy harvester 10 includes a piezoelectric device. The piezoelectric device can be configured such that an electrical voltage is generated when a force is applied to a deformation element. The deformation element can, in particular, deform elastically. Here, the deformation element can be a piezoelectric crystal. The piezoelectric device can be arranged such that it receives a gravitational force from at least one rolling element in an interaction section 11 of the circulating device 5, in particular the return tube 6a. The interaction section 11 is a section along the longitudinal direction of the circulating device 5 in which the interaction with the at least one rolling element 4 for energy generation takes place.

[0087] In Figure 3, the interaction section 11 is also located in the linear section (feedback tube 6a) next to the detection section 9. The energy harvester 7 (piezoelectric device) can be configured as a module. The energy harvester here forms part of the feedback device 6, in particular an end section of the feedback tube 6a. Specifically, the piezoelectric device can come into direct contact with the at least one rolling element 4 and thus receive the force. In other words, the energy harvester 10 can completely surround the at least one rolling element 4, thereby forming part of the feedback device 6. The energy harvester 10 can be configured to generate alternating current.

[0088] The energy harvester 10 can be coupled to the DC voltage source, for example to store energy in it.

[0089] The linear guide carriage 3 can also have an inverter, which is provided, for example, between energy harvester 10 and DC voltage source.

[0090] The linear guide carriage 3 can further include an output unit configured to output at least the information detected by the lubricant sensor 7. The output unit can be a wireless communication unit capable of exchanging data with another wireless communication unit. The wireless communication unit can be located in an end cap 32. It should be noted that the lubricant sensor 7 and / or the output unit can be powered, at least indirectly, for example via the DC voltage source, by the electrical energy provided by the energy harvester 10.

[0091] The functions and effects of the invention will now be described.

[0092] According to the invention, the linear guide carriage 3 has an electrically based lubricant sensor 7 which, in the detection section 9 located in the circulation unit 5, acquires information regarding the lubricant condition. Thus, it is possible to detect the lubricant condition in the circulation unit 5, which has the load-bearing section 5a, and thereby prevent wear of the rolling elements 4 by enabling timely relubrication, for example, when the information indicates a lubricant quantity that is below a predetermined threshold.

[0093] The linear guide carriage 3 can have a lubricant reservoir from which lubricant can be supplied to the circulation device 5. The lubricant reservoir can be refillable. The information is acquired capacitively, which enables precise measurement. In particular, the dielectric properties of the lubricant can be used to infer its condition.

[0094] As mentioned above, the detection circuit can include a voltmeter to measure the voltage across the capacitor. Furthermore, the lubricant sensor can include an electronic controller powered either by the DC voltage source or by an internal power source. The controller can include a timer for measuring time. The controller can be configured as a combination of hardware and software, or as hardware only.

[0095] Thus, a capacitance value can be determined based on a charge / discharge time, specifically by measuring the time constant at which the capacitor's voltage is charged to 63.2% of the applied DC voltage source, or discharged by 63.2%. The capacitance value can then be calculated as the quotient of the measured time constant and the resistance of the element.

[0096] Alternatively, the voltage across the capacitance and the corresponding time can be measured at intervals. Then, using a mapping method, such as the least squares method, the capacitance value with a charging curve that most closely matches the measured values ​​can be determined. Both methods thus yield a capacitance value that can be compared to a reference capacitance. The reference capacitance can be determined in advance for a given lubricant, for example, through simulation and / or analytically, based on the parameters of the circulating device, such as electrode spacing, electrode materials, rolling element materials, the distance between the electrodes and rolling elements, electrode length, the relative electrical permittivity of the lubricant, and the applied voltage of the DC power supply.

[0097] The lubricant sensor can have a non-transient storage unit in which the reference capacity is stored. If the measured capacity is equal to or greater than the reference capacity, the lubricant sensor can interpret this as information indicating that sufficient lubricant is present in the circulating system. Otherwise, insufficient lubricant is present.

[0098] Based on the parameters mentioned above and a model stored in the memory unit, the lubricant sensor can also record a numerical value as information about the amount of lubricant present in the circulating device.

[0099] It should be noted that the lubricant sensor does not have to be a single physical unit. For example, the controller and / or the storage unit can also be spatially separated from the detection circuitry. The communication unit can then, for example, send data from the section of the lubricant sensor provided on the linear guide carriage to the controller. In this context, the invention is therefore also directed to a linear guide carriage system that includes the linear guide carriage, wherein part of the lubricant sensor is provided outside the linear guide carriage.

[0100] Variations to the above details are now described.

[0101] The detection section and / or the interaction section can be located in a curved section of the circulation device. Alternatively, the detection section and / or the interaction section can be located in the load-bearing section.

[0102] Alternatively and / or additionally to the DC voltage source, an AC voltage source can be provided on the linear guide carriage. However, the information can still be acquired capacitively.

[0103] Instead of being piezoelectric, the energy harvester can also be inductively designed. It can have an induction device.The induction device can, for example, comprise: a permanent magnet for generating a static magnetic field in the interaction section, which at least one rolling element 4 must successively traverse during operation when circulating in the circulating device, wherein the rolling elements 4 are made of a magnetically permeable material, for example steel, such that the rolling elements are suitable to influence the magnetic field depending on the position of the rolling elements 4 in the interaction section; and at least one induction coil with at least one coil turn, wherein the at least one induction coil is arranged in a stationary position relative to the device for generating a static magnetic field such that, due to a change in the position of the rolling elements 4 during circulation of the rolling elements 4 through the interaction section 9, it experiences a change in magnetic flux, which induces an electrical voltage in the at least one coil turn.

[0104] Furthermore, the lubricant sensor can also acquire the information resistively. For example, a contact element can be provided in the circulating device that can make resistive contact with the rolling elements. A detection circuit of the lubricant sensor can then count the number of contacts and compare them with a reference value.

[0105] The return tube does not need to be provided as a separate element. For example, the return device can be formed directly from the base body.

[0106] The invention is suitable not only for a linear guide carriage for a linear guide device, but also for linear carriages for screw drives.

Claims

Patent claims:

1. Linear guide carriage (3) for linear movement along a guide device (2), comprising: - at least one rolling element (4), in particular a plurality thereof, by means of which the linear guide carriage (3) is movable relative to the guide device; - a circulating device (5) in which the at least one rolling element (4) is circulating at least during a relative movement between the linear guide carriage (3) and the guide device (2), characterized by - an electrically based lubricant sensor (7) arranged to detect, on the basis of an electrical property of a lubricant, information regarding a quantity and / or composition of the lubricant in a detection section (9) in the circulation device (5).

2. The linear guide carriage (3) according to claim 1, wherein the detection section (9) is arranged at least partially, in particular completely, in a linear section of the circulation device (5).

3. The linear guide carriage (3) according to claim 1 or 2, wherein the detection section (9) is arranged at least partially, in particular completely, outside a load-bearing section (5a) of the circulation device (5), in particular is arranged in a return device (6) of the circulation device (5).

4. The linear guide carriage (3) according to at least one of the preceding claims, wherein the circulation device (5) comprises, at least in the detection section (9), an electrically insulating material, in particular one formed thereof.

5. The linear guide carriage (3) according to at least one of the preceding claims, wherein the detection section (9) extends over a plurality of rolling elements (4).

6. The linear guide carriage (3) according to at least one of the preceding claims, wherein the electro-based lubricant sensor (7) is arranged to capacitively acquire the information.

7. The linear guide carriage (3) according to claim 6, wherein The electro-based lubricant sensor (7) has a detection circuit for recording the information, which has two opposing electrodes (8) between which the at least one rolling element (4), in particular a plurality thereof, is arranged.

8. The linear guide carriage (3) according to claim 7, wherein at least one of the electrodes (8), in particular both, has an electrically insulating coating on a side facing the at least one rolling element (4).

9. The linear guide carriage (3) according to claim 7 or 8, wherein the electrodes (8) are positioned opposite each other in a direction intersecting the direction of gravity and / or parallel or perpendicular to an axis of rotation (4a) of the at least one rolling element (4) in the detection section (9).

10. The linear guide carriage (3) according to at least one of claims 7 to 9, wherein at least one of the electrodes (8), in particular both, are glued to the circulation device (5).

11. The linear guide carriage (3) according to at least one of claims 6 to 10, wherein at least one of the electrodes (8), in particular both, is arranged such that it is not contactable with the at least one rolling element (4).

12. The linear guide carriage (3) according to one of claims 6 to 11, wherein the electro-based lubricant sensor has a detection circuit for capturing the information that contacts the at least one rolling element (4).

13. The linear guide carriage (3) according to at least one of claims 6 to 12, wherein the electro-based lubricant sensor (7) is configured to capture the information based on a charging and / or discharging time.

14. The linear guide carriage (3) according to at least one of claims 6 to 12, wherein the electro-based lubricant sensor (7) is configured to capture the information based on a sampling of a charging and / or discharging curve.

15. The linear guide carriage (3) according to at least one of the preceding claims, further comprising an energy harvester (10) designed to provide electrical energy to the linear guide carriage (3) due to the relative movement between the linear guide carriage (3) and the guide device (2), and in particular the linear guide carriage (3) is designed in such a way that the electrical energy provided by the energy harvester (10) can be used to operate the electro-based lubricant sensor (7).

16. Linear guide carriage system, comprising: a linear guide carriage (3) for linear movement along a guide device (2), wherein the linear guide carriage (3) comprises: - at least one rolling element (4), in particular a plurality thereof, by means of which the linear guide carriage (3) is movable relative to the guide device; - a circulating device (5) in which the at least one rolling element (4) is circulating at least during a relative movement between the linear guide carriage and the guide device, wherein the linear guide carriage system is characterized by 21 - an electrically based lubricant sensor (7) which is arranged to detect, on the basis of an electrical property of a lubricant, information regarding a quantity and / or composition of the lubricant in a detection section (9) in the circulating device.

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