Piston-cylinder unit with piston position detection unit and collimator

Abstract

The invention relates to a piston-cylinder unit (1) of a working machine, such as a wheel loader, an excavator, a dump truck, a crane or a forklift or a lifting platform, for steering, supporting, pushing out, tilting, lifting or other displacement of the working machine or a tool or other parts of the working machine. The piston-cylinder unit (1) comprises a cylinder (2), a piston (7) supported in the cylinder (2) so as to be axially movable along a longitudinal center axis (54), and a piston position detection unit (28). The piston position detection unit (28) is arranged in an assembly hole (27) and detects the axial position of the piston (7) in the cylinder (2) by means of high-frequency technology. The piston position detection unit (28) comprises an antenna (46) for sending and receiving high-frequency signals. A collimator (57) is arranged in the beam path of the antenna (46). The antenna (46) has a main radiation direction (63) extending parallel to the longitudinal center axis (54).

Description

Technical Field

[0001] The invention relates to a piston-cylinder unit comprising a cylinder, a piston supported in the cylinder so as to be axially movable, and a piston position detection unit for detecting the axial position of the piston in the cylinder.

[0002] Such piston-cylinder units are used in particular in working machines, construction machines, agricultural machines, marine machines and in mechanical engineering. In particular, they are hydraulic piston-cylinder units.

[0003] The position of the piston in the cylinder is usually used here to achieve a defined position of a tool that is indirectly connected to the piston and is therefore determined. Background Art

[0004] German patent document DE 10 2016 120 665 B3 discloses a piston-cylinder unit having a cylinder, a piston supported axially movably in the cylinder, and a piston position detection unit for detecting the axial position of the piston in the cylinder. Fig. 9 In the embodiment shown, the piston position detection unit is arranged in a mounting hole which extends radially in the cylinder and has a lens. For beam deflection, a reflector is provided which deflects the incoming and outgoing radar radiation.

[0005] German utility model DE 20 2014 001 604 U1 discloses a piston-cylinder unit having a cylinder, a piston mounted axially movably in the cylinder, and a piston position detection unit which detects the axial position of the piston in the cylinder by means of high-frequency technology.

[0006] US patent application US 2013 / 0312601 A1 discloses a piston-cylinder unit having a cylinder, a piston mounted axially movably in the cylinder, and a piston position detection unit which detects the axial position of the piston in the cylinder by means of high-frequency technology.

[0007] International patent application WO 03 / 069269 A2 discloses a piston-cylinder unit having a cylinder, a piston axially movably supported in the cylinder, and a piston position detection unit which detects the axial position of the piston in the cylinder by means of high-frequency technology. The piston position detection unit has a coupling probe, a holding system and a waveguide which are arranged in a plurality of axial holes in a cylinder head of the piston-cylinder unit.

[0008] In the prior art of hydraulic piston-cylinder units for working machines, piston position detection units are known, which detect the axial position of the piston in the cylinder by means of a magnetostrictive sensor. The structure of such a magnetostrictive sensor is relatively complex and expensive in terms of technology.

[0009] A distance measuring device having a microwave antenna assembly is known from European patent application EP 1 752 792 A1.

[0010] A waveguide coupling device and a position sensor device for a hydraulic cylinder are known from German patent application DE 10 2016 106 747 A1. Summary of the invention

[0011] The object of the present invention is to provide a piston-cylinder unit with which the axial position of the piston in the cylinder can be detected precisely with little constructional effort.

[0012] The present invention relates to a piston-cylinder unit, which has a cylinder, a piston supported in the cylinder so as to be axially movable, and a piston position detection unit. The piston-cylinder unit has a longitudinal center axis, along which the piston is supported so as to be axially movable. The cylinder has a mounting hole extending radially in the cylinder, and the piston position detection unit is arranged in the mounting hole. The piston position detection unit is used to detect the axial position of the piston in the cylinder by means of high-frequency technology and has an antenna for transmitting and receiving high-frequency signals for this purpose. A collimator is arranged in the beam path of the antenna. The antenna has a main radiation direction extending parallel to the longitudinal center axis.

[0013] The invention also relates to a piston position detection unit for detecting the position of a piston in a cylinder of a piston-cylinder unit. The piston position detection unit has a housing, which is cylindrically constructed and has a longitudinal center axis. The piston position detection unit also includes an electronic structural unit, which is arranged in the housing and has an antenna for sending and receiving high-frequency signals through the housing. The main radiation direction of the antenna extends perpendicular to the longitudinal center axis of the housing. The collimator is at least partially arranged in the housing or forms the housing together and is arranged in the beam path of the antenna.

[0014] The term "high frequency technology" as used in this application is understood to be a broad term, that is to say all frequencies between approximately 3 MHz and approximately 30 THz. In particular, it does not refer to the narrow definition of the International Telecommunication Union (InternationalenFernmeldeunion), which only understands frequencies between 3 MHz and 30 MHz under the frequency range of high frequency technology.

[0015] The piston-cylinder unit has a piston and a cylinder as main components. Here, a "cylinder" is understood to be a larger unit, which has in particular the subcomponents of a cylinder tube and a cylinder head. In the present application, a "piston" is understood to be a component that moves in the cylinder tube and forms a closed space with the cylinder tube. The piston is then in particular connected to a piston rod.

[0016] The piston-cylinder unit is in particular a hydraulic piston-cylinder unit, but can also be a pneumatic piston-cylinder unit.

[0017] The detection, determination, evaluation, regulation and presetting of the position of the piston in the cylinder of the piston-cylinder unit are meaningful for different reasons in the technical field of working machinery. Therefore, for example, it can be expected that the defined end position of the piston can be approached reliably, and thus the defined end position of the tool of the working machinery that is indirectly connected to the piston can be approached reliably. An automated and programmable sequence in the sense of approaching the different positions of the piston in sequence under computer control is also possible. In addition, the allowed working range can be limited and reliably maintained, and the piston-cylinder unit allows movement within the said working range. Overloading of the piston-cylinder unit can also be avoided by monitoring the position of the piston and the load. The corresponding load of the piston and the cylinder can be obtained by measuring pressure, temperature and position. In the case of overload, corresponding measures can be suggested or introduced.

[0018] The working machine can be, for example, a wheel loader, an excavator, a dump truck, a crane or a forklift or a lifting platform. The piston-cylinder unit is used in particular for steering, supporting, pushing out, tilting, lifting or other displacement of the working machine or a tool or other parts of the working machine.

[0019] The collimator improves the accuracy of the piston position detection unit in many aspects and thus leads to improved measurement results in the determination of the position of the piston. A "collimator" is understood to be an optical device for generating a beam path with a parallel beam from a previously non-parallel beam of a diverging source. Thus, in a first radiation direction, the collimator converts the non-parallel beam into a parallel beam. In a second, opposite radiation direction, the collimator converges the beams incident thereon in parallel. These two properties are advantageously utilized when determining the position of the piston in the cylinder by means of a high-frequency beam or a high-frequency signal.

[0020] The main radiation direction of the antenna extends parallel to the longitudinal center axis of the piston-cylinder unit. The longitudinal center axis corresponds to the axis along which the piston reciprocates. "Parallel" is to be understood in a broad sense and therefore means either "truly parallel" or identical.

[0021] The first radiation direction detection unit is assigned to the receiving function of the piston position detection unit, that is to say, to the beam that has been reflected and now first encounters the collimator on its path back to the piston position detection unit. In this case, the collimator acts as a filter, which only or at least substantially only focuses or transmits back to the piston position detection unit the beams that were previously parallel to each other and parallel to the longitudinal axis of the piston. Therefore, beams or signals that do not come from or at least do not directly come from the end-side piston bottom surface are filtered out. This undesirable beam stems from: the refraction of the collimator is actually not ideal, the beam is not ideally sent and received in a point shape, and the piston bottom surface is not ideally flat. Thus, for example, the beam is reflected from the piston bottom surface onto the inner wall of the cylinder tube and only then reaches the area of ​​the collimator. These beams cannot accurately explain the position of the piston in the cylinder tube. These beams or signals are completely or partially filtered out using a new collimator because they do not return to the receiver of the piston position detection unit and are therefore not included in the measurement result.

[0022] The second radiation direction is assigned to the transmission function of the piston position detection unit, that is, to the beam that is transmitted by the transmitter of the piston position detection unit and first hits the collimator. In this case, the collimator acts as an amplifier, which transmits more beams so that they directly and perpendicularly hit the piston bottom surface. These beams extend parallel to each other and parallel to the longitudinal axis of the piston.

[0023] The signal quality (signal-to-noise ratio) is thereby significantly improved. This leads to an increase in the accuracy of the measurement result, in particular at large distances between the piston base and the cylinder head.

[0024] The collimator can have a dielectric lens. With the aid of such a dielectric lens, the desired generation of parallel beam paths can be well achieved in the underlying high-frequency signal. The collimator can include a dielectric lens or a combination of a plurality of dielectric lenses. However, the collimator can also be designed in another suitable manner and, for example, have a Fresnel zone plate.

[0025] The dielectric lens has a lens body with a convex lens surface. The lens body is made of a dielectric material, such as dielectric plastic or dielectric ceramic. The dielectric material may include polytetrafluoroethylene, polyethylene or polypropylene, for example.

[0026] The dielectric lens has good penetration for high-frequency radiation. It has a dielectric constant (permittivity) greater than that of air and greater than that of the hydraulic medium in the piston-cylinder unit. The dielectric constant of the dielectric lens can be, for example, 20% to 50% greater than the dielectric constant of the hydraulic medium in the piston-cylinder unit. The dielectric constant difference and the curvature of the lens are coordinated with each other.

[0027] The dielectric lens may have a planar-convex lens shape. The convex side of the lens faces the piston. The flat side faces the receiver of the piston position detection unit. However, other lens shapes are also possible.

[0028] The signals transmitted radially and through the air by the approximately point-shaped transmitter of the piston position detection unit therefore first arrive at the flat side of the dielectric lens. From there, they are refracted in the direction of the central axis of the lens, since the dielectric constant of the lens material is greater than that of air. In order to achieve the desired orientation parallel to the longitudinal axis of the piston, the angle of curvature of the convex side of the lens is selected so that the desired refraction angle occurs at every point.

[0029] The collimator can be part of the piston position detection unit and in particular an integrated component of the piston position detection unit. Thus, the collimator is integrated into the piston position detection unit or these units together form an integrated structural unit. However, it is also possible that the collimator is arranged structurally separately from the piston position detection unit and that they only form a unit functionally.

[0030] The piston position detection unit can be configured as a compact insert box, which contains not only the sensor but also the evaluation electronics. Therefore, during insertion or removal, the entire piston position detection unit is installed or removed.

[0031] However, it is also possible that the housing of the piston position detection unit is fixedly mounted in the cylinder and that the electronic component is installed in the housing or removed from the housing in the assembled state of the housing. The piston position detection unit can thus be replaced without having to dismantle the piston-cylinder unit. In this case, the electronic component can be replaced while the cylinder is completely filled with oil. It is therefore not necessary to drain, fill and vent the cylinder.

[0032] The radially extending mounting holes in the cylinder can be introduced into the cylinder in a very simple manner, in particular by drilling. This starts at the outer surface of the cylinder head.

[0033] The mounting hole can have a relatively small diameter in comparison with its length, so that the mounting hole requires only a small amount of space in the axial direction of the piston-cylinder unit. The mounting hole can therefore be easily taken into account when reconfiguring the piston-cylinder unit without additional material requirements and can be introduced later in existing piston-cylinder units. For the integration of a novel piston position detection unit, no geometric changes to the piston-cylinder unit are therefore required compared to a piston-cylinder unit without such a piston position detection unit. Furthermore, the cylinder structure is not significantly weakened.

[0034] The cylinder can have a cylinder head, wherein the mounting hole is then arranged in the cylinder head of the piston-cylinder unit. The piston position detection unit can be arranged in the mounting hole such that its longest dimension extends radially in the cylinder head. In this way, the existing installation space of the cylinder head is effectively used to arrange the piston position detection unit.

[0035] The mounting hole can be effectively connected to the inner chamber of the cylinder via an axially extending sensor signal hole. The sensor signal hole enables the required transmission and reception of high-frequency sensor signals for position detection. If it is a hydraulic piston-cylinder unit, the sensor signal hole is filled with hydraulic oil.

[0036] The mounting hole can be connected to the surroundings by means of the compensation hole. In this way, it is easy to mount the piston position detection unit in the otherwise closed mounting hole and sealed by the piston position detection unit. However, it is also possible to eliminate such a compensation hole and accept a certain compression of the air in the mounting hole.

[0037] The compensation hole can be arranged, for example, in the housing of the piston position detection unit, in particular in the housing bottom. However, the compensation hole can also be arranged in the cylinder. The compensation hole can be arranged in the axial end region of the mounting hole facing away from the mounting hole opening.

[0038] The sensor signal hole through which the signal is sent does not extend over the entire bottom surface of the cylinder head. The remaining annular closed bottom surface of the cylinder head reflects the signal from the bottom surface of the piston. These reflected signals then usually reach the bottom surface of the piston again, are reflected by the bottom surface of the piston again, and then may reach the receiver of the piston position detection unit through the sensor signal hole. The position of the piston cannot be correctly determined by such a signal. In order to eliminate or reduce this problem, the cylinder head can have a cylinder head bottom surface surrounding the sensor signal hole, in which a plurality of beam deflection elements are arranged. The beam deflection elements meet another filtering function in that these beam deflection elements intentionally deflect the above-mentioned multiple reflected signals so that their angles significantly deviate from the direction parallel to the longitudinal axis of the piston. This extends the distance that the signal passes through the hydraulic medium and correspondingly increases the attenuation of the signal. Finally, these signals do not reach, only reach with a very small probability and / or only reach the receiver of the piston position detection unit in an attenuated manner. This further improves the signal quality.

[0039] The collimator can be arranged in the housing of the piston position detection unit. It is also possible that the collimator forms the housing together. Here, the collimator can be made of the same material as the rest of the housing or of a different material. However, the collimator can also be arranged outside the housing. In this case, the collimator is especially arranged in the sensor signal hole.

[0040] The beam deflecting element can be designed as a countersunk element, in particular as conical depressions spaced apart from one another in the bottom surface of the cylinder head.

[0041] The beam deflection elements can be arranged distributedly on a part or the entire cylinder head bottom surface. If only a part is involved, the beam deflection elements are preferably arranged in the area of ​​the cylinder head bottom surface surrounding the sensor signal hole.

[0042] The piston position detection unit can have a housing and an electronic structural unit arranged in the housing. The electronic structural unit can be sealed relative to the inner chamber of the cylinder by the housing. In this way, the housing prevents hydraulic oil from entering the inner chamber of the piston position detection unit, in which the piston core (i.e., the electronic structural unit) is located. The electronic structural unit at least meets the function of sending and receiving high-frequency signals. However, the electronic structural unit can also meet all other desired functions of the piston position detection unit, whereby the piston position detection unit forms a compact, self-sufficient unit. The piston position detection unit can therefore be constructed as a so-called smart sensor (Smart-Sensor). This means that, in addition to the actual sensor, the piston position detection unit also contains devices for determining, calculating, evaluating and transmitting data. The data may also include temperature.

[0043] The housing of the piston position detection unit can be made of plastic or ceramic in particular. The material and structure of the housing are selected so that they are suitable for use in this area with high pressure loads. It is quite common for pressures of about 600 bar or more to prevail in this area of ​​the piston-cylinder unit (depending on the size of the piston-cylinder unit).

[0044] In addition, the material of the housing of the piston position detection unit is selected to be transparent to high-frequency signals. For this reason, for example, metallic materials are not suitable.

[0045] The housing can be made of a thermoplastic, in particular polyaryletherketone, in particular polyetheretherketone (PEEK). This plastic has the desired properties of high compressive strength and at the same time permeability to high-frequency signals as described above. Thus, it has been shown that housings made of PEEK can be used without problems at pressures of up to 800 bar or more.

[0046] The housing of the piston position detection unit can be cylindrically configured. This configuration enables the piston position detection unit to be easily mounted in the mounting hole. However, other geometric shapes, such as rectangular or oval, are also possible.

[0047] The housing may have a first groove and a second groove on its outer circumference, and sealing members are arranged in the first groove and the second groove, respectively. The two sealing members are used to seal the inner chamber of the cylinder relative to the surrounding environment in the area where the assembly hole is located. Here, the connection between the assembly hole and the inner chamber of the cylinder is realized through the sensor signal hole. The sensor signal hole is arranged between the first groove and the second groove in the radial direction.

[0048] The effective sealing surfaces of the seals can be substantially of the same size. This allows a force-neutral arrangement of the piston position detection unit in the mounting hole. It follows that the piston position detection unit does not have to be secured in the mounting hole or only has to be secured by means of a simple securing device. The piston position detection unit can be secured by means of a simple securing element, such as a securing ring. However, it is also possible, for example, to secure the piston position detection unit in the mounting hole by means of a threaded connection.

[0049] The piston position detection unit can have a connection element for transmitting data from the electronic structural unit, wherein the connection element is connected to the electronic structural unit and the housing. The connection element can be a connection element with a wired or wireless connection. In the case of a connection element with a wired connection, it is a plug or a socket. An example that may be suitable for this is an M12 plug or an M12 socket. However, wireless transmission via WLAN, Bluetooth or other suitable wireless transmission standards is also possible.

[0050] The piston position detection unit can be arranged completely in the assembly hole, except for parts of the connecting element. This piston position detection unit can also be arranged completely in the assembly hole. This means that the outer geometry of the piston-cylinder unit is not changed compared to a piston-cylinder unit without such a piston position detection unit. Therefore, there is no need to adapt the geometry of the working machine.

[0051] The electronic component can include an antenna for transmitting and receiving high-frequency signals through the housing. The antenna can be arranged on the electronic component and in the housing in such a way that the high-frequency signal is directed through the sensor signal opening. The material of the housing and the free space created by the sensor signal opening thus allow interference-free transmission and reception of high-frequency signals.

[0052] The housing can have a first orientation element and the electronic component can have a corresponding second orientation element, wherein the first orientation element and the second orientation element are coordinated with one another so that the electronic component can only be completely installed in the housing in exactly one orientation. In this way, incorrect installation of the electronic component in the housing is prevented.

[0053] The first orientation element can be configured as a groove arranged eccentrically in the axial end region of the housing, and the second orientation element can be configured as a tongue formed likewise eccentrically in the corresponding axial end region of the electronic structural unit, which together form a tongue-and-groove connection. Therefore, the tongue can be arranged in the groove in only one relative arrangement relative to the groove. A third orientation element can be arranged on the housing and a corresponding fourth orientation element can be arranged on the assembly hole or cylinder. The third orientation element can be, for example, a protrusion, and the fourth orientation element can be a recess, or vice versa. Other geometric configurations are also possible. In this way, it is ensured that the housing can only be arranged in the cylinder of the piston-cylinder unit in exactly one orientation.

[0054] The directional element generally ensures that the main radiation direction of the antenna is correctly oriented. The main radiation direction of the antenna then extends perpendicularly to the longitudinal center axis of the housing of the piston position detection unit and along the longitudinal center axis of the piston-cylinder unit or parallel thereto. The main radiation direction of the antenna extends in the direction of the sensor signal opening and the piston.

[0055] The piston position detection unit can have a housing and an electronic component arranged in the housing, wherein the piston position detection unit is designed and arranged in the mounting hole in such a way that the inner chamber of the cylinder is sealed with respect to the surroundings of the piston-cylinder unit and the electronic component can be removed from the housing and installed in the housing without eliminating the sealing effect. As a result, the electronic component can be installed in the housing and removed from the housing when the piston-cylinder unit is filled with oil. This means that in the event of a technical fault in the electronic component, the electronic component can be removed from the housing while the housing remains installed in the mounting hole.

[0056] The high frequency signal may be a microwave signal.

[0057] The high-frequency signal can have a frequency of at least 20 GHz, in particular at least 50 GHz, in particular at least 100 GHz, in particular between 20 GHz and 400 GHz, in particular between 100 GHz and 300 GHz, in particular between 100 GHz and 150 GHz, in particular about 120 GHz.

[0058] The high frequency signal may be a continuous wave signal. The high frequency signal may in particular be a frequency modulated continuous wave signal. Different frequencies may be sent in a certain order. For example, this may be a frequency of 120 GHz, 121 GHz, 122 GHz, etc.

[0059] Frequency modulated continuous wave radar (FMCW radar) continuously transmits a transmission signal with a changing frequency. Unlike unmodulated (CW radar) radar, FMCW radar can change its operating frequency during the measurement. This change in frequency provides the time reference required for measuring the distance to the object to be measured (here the piston). The distance measurement is then achieved by comparing the frequency of the received signal with the transmitted signal. Since this measurement principle itself is known in the prior art, a further description is omitted.

[0060] Advantageous developments of the invention are apparent from the description and the drawings.

[0061] The advantages of features and combinations of features described in the description are merely exemplary and may act alternatively or cumulatively without necessarily having to be achieved by embodiments according to the invention.

[0062] With regard to the disclosure of the original application documents and patents (but not the scope of protection), the following applies: Other features can be derived from the drawings (in particular from the illustrated geometric shapes of the multiple components and their relative dimensions to each other and their relative arrangement and functional connection). In the case of deviation from the embodiments of this description, the features of different embodiments of the present invention can also be combined and inspired by this. This also relates to features that are shown in separate drawings or mentioned when describing separate drawings. These features can also be combined with features of the present invention. Similarly, for other embodiments of the present invention, the features listed in the description can be omitted.

[0063] In the description, features mentioned in terms of their quantity are to be understood as: there is exactly this quantity or there is a greater quantity than the mentioned quantity, without the explicit use of the adverb "at least". That is, for example, when a collimator is mentioned, it is to be understood as: there is exactly one collimator, two collimators or more collimators. These features can be supplemented by other features or be the only features, from which the corresponding results arise.

[0064] The accompanying drawings included in the specification do not limit the scope of the present invention, but are only used to make the present invention easier to understand. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The invention is explained and described in greater detail below with reference to preferred exemplary embodiments shown in the drawings.

[0066] Figure 1 A sectional view of a first exemplary embodiment of a novel piston-cylinder unit with a novel piston position detection unit is shown.

[0067] Figure 2 Show according to Figure 1An enlarged view of a portion of a piston-cylinder unit.

[0068] Figure 3 Show Figure 2 Detail of the piston-cylinder unit in A.

[0069] Figure 4 Shown from above Figure 1 View of a part of the piston-cylinder unit.

[0070] Figure 5 Show according to Figure 1 An exploded perspective view of a portion of a piston-cylinder unit.

[0071] Figure 6 Show according to Figure 1 A perspective view of an exemplary embodiment of an electronic structural unit of a piston position detection unit of a piston-cylinder unit.

[0072] Figure 7 Show according to Figure 1 Perspective view of the piston position detection unit of a piston-cylinder unit with an integrated collimator.

[0073] Figure 8 Show according to Figure 7 A partially cutaway perspective view of a piston position detection unit.

[0074] Fig. 9 Show according to Figure 1 Perspective view of the cylinder head of a piston-cylinder unit.

[0075] Fig.10 A sectional view of a second exemplary embodiment of a novel piston-cylinder unit with a novel piston position detection unit is shown.

[0076] Fig.11 Show according to Fig.10 An enlarged view of a portion of a piston-cylinder unit.

[0077] Fig.12 Show Fig.11 Detail of the piston-cylinder unit in B.

[0078] Fig.13 Show according to Fig.10 An exploded perspective view of a portion of a piston-cylinder unit.

[0079] Fig.14 Show according to Fig.10 Perspective view of the piston position detection unit of a piston-cylinder unit.

[0080] Fig.15 Show according to Fig.14A partially cutaway perspective view of a piston position detection unit.

[0081] Fig.16 Show according to Fig.10 Perspective view of the collimator of the piston-cylinder unit.

[0082] Fig.17 Show according to Fig.10 Perspective view of the cylinder head of a piston-cylinder unit. DETAILED DESCRIPTION

[0083] Figure 1-9 A first exemplary embodiment of the novel piston-cylinder unit 1 and its parts are shown in different views.

[0084] exist Figure 1 In FIG. 1 , the curved interrupted line indicates that the piston-cylinder unit 1 is actually longer and only a portion is shown. Figure 2 , 4 Similar interrupt lines exist in and 5. Figure 3 , the diagram ends at the straight interruption line. The same applies to Fig. 9 , 10 , 11 and 12.

[0085] The piston-cylinder unit 1 has a cylinder 2 with a cylinder tube 55, an interior space 3 and a cylinder head 4. A bearing sleeve 5 is arranged in the region of the cylinder head 4 for supporting the piston-cylinder unit 1 on a working machine (not shown).

[0086] The present exemplary embodiment concerns a hydraulic piston-cylinder unit 1, whereby the inner chamber 3 is filled with oil 53. For this purpose, the cylinder 2 has an oil connection 6 and an oil connection 24. Oil lines, not shown here, are connected to the oil connections 6, 24. A hydraulic pump, likewise not shown, is used to apply pressure to the piston 7 in a manner known per se with the aid of oil 53, so that the piston 7 and the piston rod 8 connected thereto move in the corresponding direction along the longitudinal center axis 54 of the piston-cylinder unit 1. In this way, the oil enters the inner chamber 3 of the cylinder 2 through the oil connections 6, 24 or leaves this inner chamber, depending on the direction of movement of the piston 7 in the cylinder 2. Here, in Figure 1 and Figure 2 2 shows the position of the piston 7 which is completely displaced to the right (ie the retracted position of the piston-cylinder unit 1 ).

[0087] As mentioned above, the piston-cylinder unit 1 also has a piston 7. The piston 7 is connected to a piston rod 8, at one axial end of which a piston rod eye 9 is arranged. The piston rod eye 9 also has a bearing sleeve 10. The bearing sleeve 10 is used to indirectly connect the piston 7 to a tool or other part of the working machine that is not shown.

[0088] The piston rod 8 is supported in a translationally movable manner in the axial direction along the longitudinal center axis 54 by means of a guide sleeve 11. A rod seal 12, an O-ring 13 and a support ring 14 are provided for support and sealing. A further O-ring 15, a scraper 16 and a sliding bearing 17 are arranged at the other axial end of the guide sleeve 11.

[0089] The piston 7 is arranged on the piston rod 8 in a rotationally fixed manner and is secured by means of a securing nut 18. Furthermore, an O-ring 19, a piston guide ring 20, a piston seal 21, a further piston guide ring 22 and a weld seam 23 are arranged on the piston 7.

[0090] In this way, the piston 7 together with the piston rod 8 and the piston rod eye 9 is supported in a sealing manner in the cylinder tube 55 of the cylinder 2 in a reciprocating translational manner.

[0091] The part of the inner chamber 3 formed by the cylinder tube 55 is connected to the chamber 25 in the cylinder head 4, which also forms the inner chamber 3 and is filled with oil 53. The chamber 25 is connected to the oil channel 24. The axially extending sensor signal hole 26 is connected to the chamber 25. The sensor signal hole 26 is therefore connected to the inner chamber 3 and filled with oil 53.

[0092] The sensor signal hole 26 is in turn connected to a mounting hole 27 extending radially in the cylinder 2. The mounting hole 27 extends to the upper surface outside the cylinder head 4 and can be connected to the surrounding environment by means of a compensation hole (not shown).

[0093] The cylinder head 4 has a cylinder head bottom surface 59 extending annularly around the sensor signal hole 26. A plurality of beam deflection elements 60 are arranged in the cylinder head bottom surface 59. These are countersunk elements 61 which are configured as conical recesses 62 spaced apart from one another. The function of the beam deflection elements 60 will be described below.

[0094] A piston position detection unit 28 is arranged in the assembly hole 27. The piston position detection unit 28 is used to detect the axial position of the piston 7 in the cylinder 2 by means of high-frequency technology. The details of the piston position detection unit 28 can be found in Figure 3 The enlarged image and Figure 5 The structure of the electronic structural unit 30 is best seen in the exploded view of Figure 6 For the sake of clarity, the components of the piston position detection unit 28 are shown in Figure 1 and Figure 2 Not indicated by reference numerals.

[0095] The piston position sensing unit 28 has a housing 29 and an electronic component unit 30 which is arranged in the housing 29 .

[0096] The piston position detection unit 28 has a collimator 57 which in this case forms the housing 29 together. However, the collimator 57 can also be arranged in the housing 29 or outside the housing 29. The collimator 57 is designed here as a dielectric lens 58. The function of the collimator 57 will be described below.

[0097] The housing 29 is cylindrical and has a Figure 5 ) is closed by a bottom 31. The opposite upper end is open so that the electronic component 30 can be installed from there. The housing 29 is made of a material that is transparent to high-frequency signals. This is in particular a thermoplastic.

[0098] The housing 29 has a first orientation element 32 in the region of its closed bottom 31, which is designed as a groove 33 and is arranged eccentrically in the cylindrical housing 29. A second orientation element 34 of the electronic structural unit 30 engages in this first orientation element 32. The second orientation element 34 is designed as a tongue 35. In this way, a tongue-and-groove connection is formed. The second orientation element 34 is also formed eccentrically on the electronic structural unit 30. In this example, the tongue 35 is formed by a circuit board 36 of the electronic structural unit 30. Therefore, the entire circuit board 36 is arranged eccentrically. However, this can also be realized differently.

[0099] The correct orientation of the housing 29 in the mounting hole 27 is achieved by means of a third orientation element 49, which is designed here as a projection 50 on the housing 29. The mounting hole 27 has a corresponding fourth orientation element 51, which is designed here as a recess 52. For better visibility, this area is Figure 4 In the figure, it is additionally shown enlarged.

[0100] The printed circuit board 36 is connected at its opposite axial end to a connecting element 37 for transmitting data from the electronic component 30. In its assembled state, the connecting element 37 is connected both to the electronic component 30 and to the housing 29. The connection to the housing 29 is realized, for example, by a screw connection 38. In the present case, the connecting element 37 is an M12 plug. However, other connecting elements 37 are also possible.

[0101] The housing 30 and thus the piston position sensing unit 28 are securely mounted in the mounting opening 27 by means of a securing ring 39 .

[0102] The housing 29 has a first groove 40, a second groove 41 and a third groove 42 on its outer circumference. A first seal 43 is arranged in the first groove 40, a second seal 44 is arranged in the second groove 41, and a third seal 45 is arranged in the third groove 42. The first seal 43 in the first groove 40 is used for sealing against the surrounding environment.

[0103] In contrast, the seals 44, 45 form a seal pair and are used to seal the inner chamber 3 of the cylinder 2 which is filled with oil 53. Here, the sensor signal hole 26 in which the oil 53 is located is arranged between the first groove 40 and the second groove 41 in the radial direction (i.e. in the direction of the longitudinal center axis 47). The effective sealing surfaces of the seals 44, 45 are approximately the same size, so that the piston position detection unit 28 is arranged in a force-neutral manner in the mounting hole 27.

[0104] A series of electronic components are arranged on the circuit board 36. This includes an antenna 46, which is designed to send and receive high-frequency signals through the housing 29. Other components are used to determine, calculate, evaluate and transmit data in the piston position detection unit 28, which are familiar to those skilled in the art and are therefore not explained in detail.

[0105] The antenna 46 is arranged on the circuit board 36, the circuit board 36 is oriented in the housing 29, and the housing 29 is oriented in the cylinder head 4 such that the high-frequency signal of the antenna 46 is directed through the sensor signal opening 26. Therefore, the main radiation direction 63 of the antenna 46 extends perpendicularly to the longitudinal center axis 47 of the housing 29 and parallel to the longitudinal center axis 54 of the piston-cylinder unit 1. Therefore, the main radiation direction 63 of the antenna 46 extends along the longitudinal center axis 48 of the sensor signal opening 26 or is offset relative to it so that the high-frequency signal can be directed from the antenna 46 through the collimator 57 and the sensor signal opening 26 to the piston 7 and the signal reflected by the piston can be received by the antenna 46.

[0106] When the piston position detection unit 28 is in operation, it transmits a high-frequency signal via the antenna 46 through the collimator 57, the housing 29, the sensor signal hole 26, and (depending on the position of the piston 7) through a portion of the inner chamber 3. The signal encounters the piston 7, is reflected by the piston, returns along the same path, and is received by the antenna 46.

[0107] The accuracy of the piston position detection unit 28 is improved in many aspects by the collimator 57. The collimator 57 generates a beam path with a parallel beam from a previously non-parallel beam, and vice versa. Thus, in the transmission direction, the collimator 57 converts the non-parallel beams from the antenna 46 into parallel beams. The collimator 57 collects the signal beams reflected by the piston 7 that enter the collimators in parallel in the opposite receiving direction, and integrates the signal beams so that the signals are received by the antenna 46.

[0108] The accuracy of the piston position detection unit 28 is further improved by the beam deflection element 60. The beam deflection element 60 has intentionally deflected the multiply reflected signals (=error signals) so that their angle deviates significantly from the direction parallel to the longitudinal center axis 54 of the piston 7. This prolongs the path of the error signals through the oil 53 and correspondingly increases the attenuation of the error signals. Ultimately, these error signals do not reach the antenna 46, only with a small probability and / or only in an attenuated state.

[0109] The electronic component unit 30 uses its other electronic components and the programs implemented by these components to evaluate and thus determine the instantaneous position of the piston 7 along the longitudinal center axis 54. This determination can be performed permanently, at defined time intervals or at specific points in time. The result or the command associated therewith is transmitted via the connecting element 37 to the electronic computing unit of the working machine associated therewith, a part of which is the piston-cylinder unit 1.

[0110] Figure 10-17 A second exemplary embodiment of the novel piston-cylinder unit 1 and its parts are shown in different views. Figure 4 and Figure 6 Since there is a large degree of agreement between the first and second exemplary embodiments of the piston-cylinder unit 1 , reference is made to the embodiments already given above.

[0111] However, the piston position detection unit 28 and the sensor signal hole 26 are constructed differently. The collimator 57 is a separate component arranged in the enlarged sensor signal hole 26.

[0112] Reference numerals list

[0113] 1 Piston-cylinder unit

[0114] 2 cylinders

[0115] 3Inner Room

[0116] 4 cylinder head

[0117] 5 Bearing sleeve

[0118] 6 Oil interface

[0119] 7 Piston

[0120] 8 Piston rod

[0121] 9 Piston rod eyelet

[0122] 10 Bearing sleeve

[0123] 11 Guide sleeve

[0124] 12 Rod seal

[0125] 13 O-ring

[0126] 14 Support ring

[0127] 15 O-ring

[0128] 16 Scraper

[0129] 17 Sliding bearings

[0130] 18 Locking nut

[0131] 19 O-ring

[0132] 20 Piston guide ring

[0133] 21 Piston seal

[0134] 22 Piston guide ring

[0135] 23 Weld

[0136] 24 Oil connection

[0137] 25 Chamber

[0138] 26 Sensor signal hole

[0139] 27 Mounting holes

[0140] 28 Piston position detection unit

[0141] 29 Shell

[0142] 30 Electronic building blocks

[0143] 31 bottom

[0144] 32 First directional element

[0145] 33 slots

[0146] 34 Second directional element

[0147] 35 Tenon

[0148] 36 Circuit Board

[0149] 37 Connecting elements

[0150] 38 Threaded connection

[0151] 39 Safety ring

[0152] 40 First Slot

[0153] 41 Second slot

[0154] 42 Third slot

[0155] 43 First seal

[0156] 44 Second seal

[0157] 45 Third seal

[0158] 46 Antenna

[0159] 47 longitudinal axis

[0160] 48 longitudinal axis

[0161] 49 Third directional element

[0162] 50 protrusion

[0163] 51 Fourth Directional Element

[0164] 52 recess

[0165] 53 Oil

[0166] 54 longitudinal axis

[0167] 55 Cylinder pipe

[0168] 56 Air

[0169] 57 Collimator

[0170] 58 Dielectric lens

[0171] 59 Cylinder head bottom

[0172] 60 Beam deflection element

[0173] 61 Countersunk components

[0174] 62 Depression

[0175] 63 Main radiation direction

Claims

1. A piston-cylinder unit (1), comprising: A cylinder (2) having a mounting hole (27) extending radially in the cylinder (2); A piston (7) supported in the cylinder (2) so as to be axially movable along a longitudinal center axis (54); A piston position detection unit (28) is arranged in the assembly hole (27) and detects the axial position of the piston (7) in the cylinder (2) by means of high-frequency technology, wherein: The piston position detection unit (28) has an antenna (46) for sending and receiving high-frequency signals; a collimator (57) arranged in the beam path of the antenna (46), It is characterized in that The antenna (46) has a main radiation direction (63) which extends parallel to the longitudinal center axis (54).

2. The piston-cylinder unit (1) according to claim 1, characterized in that The collimator (57) has a dielectric lens (58).

3. The piston-cylinder unit (1) according to claim 1 or 2, characterized in that The collimator (57) is an integrated component of the piston position detection unit (28).

4. The piston-cylinder unit (1) according to claim 1 or 2, characterized in that The cylinder (2) has a cylinder tube (55) and a cylinder head (4). The assembly hole (27) is arranged in the cylinder head (4), The piston position detection unit (28) is arranged in the assembly hole (27) such that the longest dimension of the piston position detection unit extends radially in the cylinder head (4).

5. The piston-cylinder unit (1) according to claim 4, characterized in that The assembly hole (27) is operatively connected to the inner chamber (3) of the cylinder (2) via an axially extending sensor signal hole (26).

6. The piston-cylinder unit (1) according to claim 5, characterized in that The cylinder head (4) has a cylinder head bottom surface (59) surrounding the sensor signal hole (26), and a plurality of beam deflection elements (60) are arranged in the cylinder head bottom surface.

7. The piston-cylinder unit (1) according to claim 6, characterized in that The beam deflecting element (60) is designed as a countersunk element (61).

8. The piston-cylinder unit (1) according to claim 6 or 7, characterized in that The beam deflection element (60) is designed as conical depressions (62) spaced apart from one another in the cylinder head bottom surface (59).

9. The piston-cylinder unit (1) according to claim 5, characterized in that The piston position detection unit (28) has a housing (29) and an electronic component unit (30) arranged in the housing (29).

10. The piston-cylinder unit (1) according to claim 9, characterized in that The collimator (57) is at least partially arranged in the housing (29) or forms the housing (29) together.

11. The piston-cylinder unit (1) according to claim 9 or 10, characterized in that The electronic component (30) has an antenna (46) and the antenna is designed to transmit and receive high-frequency signals through the housing (29). The antenna (46) is arranged on the electronic component (30) and in the housing (29) in such a way that the high-frequency signal is directed through the sensor signal opening (26).

12. The piston-cylinder unit (1) according to claim 9 or 10, characterized in that The housing (29) has a first orientation element (32) and the electronic component (30) has a corresponding second orientation element (34), wherein the first orientation element (32) and the second orientation element (34) are coordinated with one another such that the electronic component (30) can only be completely installed in the housing (29) in exactly one orientation.

13. The piston-cylinder unit (1) according to claim 12, characterized in that The first alignment element (32) is designed as a groove (33) arranged eccentrically in an axial end region of the housing (29), and the second alignment element (34) is designed as a tongue (35) formed likewise eccentrically in a corresponding axial end region of the electronic component (30).

14. The piston-cylinder unit (1) according to claim 1 or 2, characterized in that The piston position detection unit (28) has a housing (29) and an electronic structural unit (30) arranged in the housing (29), wherein the piston position detection unit (28) is designed and arranged in the assembly hole (27) in such a way that the inner chamber (3) of the cylinder (2) is sealed relative to the surrounding environment of the piston-cylinder unit (1) and the electronic structural unit (30) can be removed from the housing (29) and installed in the housing (29) without eliminating the sealing effect.

15. A piston position detection unit (28) for detecting the position of a piston (7) in a cylinder (2) of a piston-cylinder unit (1), wherein: The piston-cylinder unit (1) is designed according to any one of claims 1 to 14, Features: a housing (29) which is cylindrical and has a longitudinal center axis (47); an electronic component (30) which is arranged in the housing (29) and has an antenna (46) for transmitting and receiving high-frequency signals through the housing (29), wherein a main radiation direction (63) of the antenna (46) extends perpendicularly to a longitudinal center axis (47) of the housing (29); A collimator (57) is arranged at least partially in the housing (29) or forms the housing (29) together with the housing (29) and is arranged in the beam path of the antenna (46).

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