Piston Cylinder Unit

Abstract

The piston motion sensor 28 of the present invention is disposed in a lateral bore 27 in the cylinder head 4 of the piston cylinder unit 1, the lateral bore 27 being separated from a pressurizing chamber 33 which pressurizes the piston 7 of the piston cylinder unit 1. This separation is achieved by a collimator 35 disposed in the beam path of the sensor signal being sealed from the sensor signal channel 26 by a seal 37. The seal can be used to allow the housing of the piston motion sensor 28 to be removed from the lateral bore 27 without fluid leaking from the pressurizing chamber 33 to the environment. The piston cylinder unit 1 of the present invention is used, for example, in a work machine, a construction machine, an agricultural machine, a marine machine, a wheel loader, an excavator, a dump truck, a crane, a forklift, or a lifting platform.

Description

[Technical field]

[0001] The present invention relates to a piston cylinder unit. In particular, the present invention relates to a piston cylinder unit that can be used in a working machine, in particular in a construction machine, an agricultural machine, a marine machine, a wheel loader, an excavator, a dump truck, a crane, a forklift, a lifting platform or other working machines known to be used in mechanical engineering. The piston cylinder unit serves, for example, to handle, support, slide, tilt, lift, lower or otherwise move parts of the working machine, in particular tools, rockers or other parts of the working machine. Preferably, it is a hydraulic piston cylinder unit. [Background technology]

[0002] A typical piston-cylinder unit is known from US Pat. No. 5,399,633.

[0003] A known piston-cylinder unit from the above-mentioned patent document is shown in Fig. 1. The dashed lines in Fig. 1 make it clear that the piston-cylinder unit 1 can in fact be made longer and that only a part of the piston-cylinder unit 1 is depicted. The piston-cylinder unit 1 comprises a cylinder 2 with a cylinder tube 31, an interior space 3 and a cylinder head 4. The cylinder tube 31 is connected to the cylinder head 4 via a welded seam 23. A bearing bush 5 is arranged in the cylinder head 4.

[0004] The patent document 1 deals with a hydraulic piston-cylinder unit 1, which means that the internal space 3 is filled with a hydraulic fluid 29, in particular oil. The cylinder 2 has a connector 6 and a connector 24 for this purpose. In the patent document 1, a hydraulic circuit, not shown, is connected to a hydraulic pump and a switching valve by the connector 6 and the connector 24. The connectors 6 and the connector 24 open to the assigned pressurized chambers 32 and 33, respectively. The pressurized chambers 32 and 33 are formed in the internal space 3 and are separated from each other by the piston 7. The piston 7 is movable along the longitudinal central axis 30 of the cylinder 2, with the pressurized chambers 32 and 33 sealed.

[0005] In the above-mentioned patent document 1, the actuating force acting on the piston 7 is hydraulically generated in both directions along the longitudinal central axis 30 according to the pressure generated by the hydraulic circuit of the connector 6 and the connector 24, and the resulting adjustment movement of the piston 7 results in a change in the volume of the pressurizing chamber 32 and the pressurizing chamber 33. FIG. 1 of the above-mentioned patent document 1 shows the position in which the piston 7 has been moved completely to the right, i.e., the retracted position of the piston-cylinder unit 1. The piston 7 is connected to a piston rod 8, at the outer end of which a piston rod eye 9 is arranged. The piston rod eye 9 also has a bearing bush 10. The bearing bush 5 and the bearing bush 10 serve to connect the piston-cylinder unit 1 to parts of the working machine for movement relative to each other by the piston-cylinder unit 1 and / or for forces being applied by the piston-cylinder unit 1.

[0006] The piston rod 8 is supported by the guide bush 11 so as to be movable axially along the longitudinal central axis 30. A rod seal 12, an O-ring 13 and a support ring 14 are provided for bearing and sealing. At the other end of the guide bush 11, an additional O-ring 15, a wiper 16 and a slide bearing 17 are arranged. The piston 7 is arranged rotatably and fixedly on the piston rod 8 and fixed by a fixing nut 18. Furthermore, an O-ring 19, a piston guide ring 20, a piston seal 21 and another piston guide ring 22 are arranged on the piston 7. In this way, the piston 7 is supported in a sealed manner together with the piston rod 8 and the piston rod eye 9 in the cylinder tube 31 of the cylinder 2 and moves back and forth.

[0007] Also, in the above-mentioned Patent Document 1, the subchamber 25 of the pressurized chamber 33 of the cylinder head 4 is attached to a part of the pressurized chamber 33 bounded by the cylinder tube 31. The subchamber 25 is also connected to the connector 24. An axially extending sensor signal channel 26 leads to this subchamber 25. The sensor signal channel 26 is also part of the pressurized chamber 33 and is therefore filled with hydraulic fluid. The sensor signal channel 26 is connected to a radially extending transverse hole 27 with respect to the longitudinal central axis 30 of the cylinder head 4. The transverse hole 27 extends to the outer surface of the cylinder head 4 and can be connected to the surrounding environment by a compensation hole, not shown. The piston motion sensor 28 is arranged inside the transverse hole 27. The piston motion sensor 28 is used to detect the axial position of the piston 7 in the cylinder 2 by means of high-frequency technology. For this purpose, the piston motion sensor 28 emits a high-frequency signal that hits the end face of the piston 7 or the piston rod 8 through the sensor signal channel 26, the subchamber 25 and the pressurized chamber 33 and returns to the piston motion sensor 28 after being reflected at this end side. The path covered by a transmitted signal, and in particular the terminating side, can be ascertained from the reflected signal by evaluating high frequency techniques, in particular the travel time.

[0008] In the exemplary embodiment shown in Figure 1, the piston motion sensor 28 is pressurized with hydraulic fluid. The sensor housing of the piston motion sensor 28 has seals that axially seal the piston motion sensor 28 on both sides of the sensor signal channel 26 to prevent hydraulic fluid from leaking from the pressurized chamber 33 through the side hole 27. The piston motion sensor 28 has a connector plug 34 that is attached to the sensor housing of the piston motion sensor 28 and extends radially from the cylinder head 4. For more details, see US Patent Publication 2007 / 0139994, which is the subject of this disclosure.

[0009] Further development of the piston cylinder unit 1 of the above-mentioned Patent Document 1 is known from Patent Document 2. In Patent Document 2, it is proposed to place a collimator or a dielectric lens in the beam path of the high-frequency signal, which helps to increase the measurement accuracy of the piston motion sensor. The collimator is understood to be an optical device that generates a beam path such that a beam generated non-parallel from a source becomes a parallel beam. In addition, in a first radiation direction from the transmitting unit of the piston motion sensor to the end side of the piston or piston rod, the collimator converts the non-parallel beam emitted by the piston motion sensor into a parallel beam, and these parallel beams are then reflected in parallel from the end side of the piston or piston rod. The reflected high-frequency beams are then focused again in the opposite second radiation direction by the collimator and received and analyzed by the receiving unit of the piston motion sensor. The collimator also functions as a kind of filter that focuses only or almost all of the high-frequency beams that originally travel parallel to each other or parallel to the longitudinal axis of the piston on the piston motion sensor. Thus, it is possible to filter out high frequency beams which do not originate, or at least do not originate directly, from the bottom surface of the piston at the end side, which in practice is due to the fact that the collimator refraction is not ideal, the beam is not emitted and received ideally in a point-like manner, and the bottom surface of the piston is not ideally flat.

[0010] Also, in the above-mentioned Patent Document 2, the use of the collimator is aimed at improving the signal-to-noise ratio. The collimator may have a dielectric lens. It is also possible to use a plurality of dielectric lenses or Fresnel zone plates. The dielectric lens may have a convex lens surface and / or may be made of or contain a dielectric plastic or dielectric ceramic, polytetrafluoroethylene, polyethylene or polypropylene. The dielectric lens preferably has a dielectric constant (permittivity) greater than that of air and the hydraulic fluid in the piston-cylinder unit. The dielectric constant is, for example, 20% to 50% greater than that of the hydraulic fluid in the piston-cylinder unit. The difference in the dielectric constant and the curvature of the dielectric lens are consistent with each other. The dielectric lens may have a plano-convex lens shape. The convex surface of the lens may face the piston.

[0011] In contrast, the planar side faces the piston motion sensor. The collimator can be formed by the sensor housing or can be structurally separate from the piston motion sensor itself and the sensor housing. The piston motion sensor can be formed as a compact self-contained cartridge containing both the sensor and the analysis electronics. The piston motion sensor is disposed inside the side hole such that the longest dimension of the piston motion sensor extends in the direction of the longitudinal axis of the side hole. The beam deflector can be disposed at the bottom of the subchamber away from the sensor signal channel to prevent falsification of the measurement results. The collimator can be disposed in the sensor signal channel. For more details, see US Pat. No. 6,233,339, which is the subject of this disclosure. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] DE 102019122121 A1

[0013] [Patent Document 2] European Patent Application Publication No. 3957868 Summary of the Invention [Problem to be solved by the invention]

[0014] The invention is based on the task of proposing a piston-cylinder unit with a piston motion sensor integrated in the cylinder head, which unit is improved with regard to the mounting and / or dismantling effort and / or the multiplicity of parts and / or the stress on the piston motion sensor. [Means for solving the problem]

[0015] The object of the present invention is achieved according to the invention with the features of the independent patent claims. Further preferred configurations according to the invention can be taken from the dependent patent claims.

[0016] The invention proposes a piston-cylinder unit comprising a cylinder with a cylinder head, a piston axially movable in the cylinder and pressurized with a pressurized fluid via a pressure chamber, and a piston motion sensor. The piston motion sensor is arranged inside a lateral bore of the cylinder head with a longitudinal axis. The piston motion sensor emits a sensor signal. The sensor signal travels from the piston motion sensor through the pressure chamber to the piston or piston rod. The sensor signal is reflected by the piston or piston rod. After reflection, the sensor signal travels again through the pressure chamber to the piston motion sensor for analysis, in particular the piston movement (e.g. stroke) being detected by the change in execution time of the sensor signal depending on the position of the piston or piston rod. In this respect, the piston-cylinder unit can also be formed according to various variants of the prior art cited above.

[0017] The invention is based on the recognition that in the embodiment known from the above-mentioned patent document 2, the housing of the piston motion sensor is pressurized by a high-pressure fluid of up to 600 bar or more, which requires a suitable dimensioning of the housing and a suitable selection of the material of the housing. Furthermore, the embodiment known from the above-mentioned patent document 2 acknowledges that when the housing of the piston motion sensor is installed, the pressurization chamber filled with fluid is connected to the surrounding environment through the side hole, and the pressurization chamber may be emptied. For this reason, the above-mentioned patent document 2 proposes that the housing, which is sealed inside the side hole via sealings arranged on both sides of the sensor signal channel connecting the side hole and the pressurization chamber, should always remain inside the side hole to prevent the pressurization chamber from being emptied. However, a suitable design of the electronic unit of the piston motion sensor and the housing of the piston motion sensor must be such that the electronic unit can be removed from the housing and the side hole when the housing is arranged inside the side hole.

[0018] The invention proposes that the side hole (and the piston motion sensor arranged inside the side hole) is fluidically separated from the pressurization chamber. As a result, the side hole is not pressurized by the fluid in the pressurization chamber. This means that the pressure of the fluid does not act on the housing of the piston motion sensor, and when the housing of the piston motion sensor is removed (together with the electronic unit in certain circumstances), the sealing of the pressurization chamber is nevertheless ensured and no fluid leaks from the pressurization chamber through the side hole to the surrounding environment. Nevertheless, in order to be able to transmit the sensor signal between the piston motion sensor and the pressurization chamber, the piston and the piston rod, the separation part, which is responsible for the fluidic separation and which is arranged in the area of ​​the beam path of the sensor signal, is suitably formed so that the sensor signal can pass through (with sufficiently small attenuation and / or with sufficiently small scattering or undesired deflection). The separation part thus ensures on the one hand the function of fluidic separation and on the other hand the function of transmission or passage of the sensor signal.

[0019] Within the scope of the present invention, there are various options for the fluid separation or the separation part used for this purpose. For example, the separation can be via a wall between the side hole formed by the cylinder head and the pressurization chamber. On the other hand, it is also possible for the side hole and the pressurization chamber to be connected to each other by a sensor signal channel through which the sensor signal passes. In this case, the separation part can be arranged in the sensor signal channel and the fluid separation can be performed there.

[0020] In a particular proposal of the invention, the side hole is fluidically isolated from the pressurized chamber via a seal, which for example may fluidically isolate the aforementioned sensor signal channel.

[0021] In a particular proposal of the invention, the sensor signal travels from the piston motion sensor to the pressurized chamber and / or from the pressurized chamber to the piston motion sensor after reflection on the piston or piston rod via a dielectric lens or collimator. The dielectric lens or collimator serves to align and / or bundle the sensor signal (see also the preface of the above-mentioned patent document 2 and the comments on the dielectric lens or collimator in this document itself). The dielectric lens or collimator is arranged in the sensor signal channel. In this case, a sealing part is arranged between the dielectric lens or collimator and the sensor signal channel. In this embodiment, the separation between the pressurized chamber and the side hole is jointly performed by the dielectric lens or collimator on the one hand and by the sealing part on the other hand. The dielectric lens or collimator is used multifunctionally, since on the one hand it ensures that the beam path of the sensor signal is influenced and on the other hand (in cooperation with the sealing part) it ensures the desired fluid separation. By way of a non-limiting example, the dielectric lens or collimator has in its outer circumferential area a circumferential groove in which a sealing part, for example an O-ring, is accommodated. The sealing portion is radially reinforced to provide a seal between the dielectric lens or collimator and the inner surface of the sensor signal channel.

[0022] Further embodiments according to the invention are based in particular on the realization that for the required accuracy of the measurement results of a piston motion sensor arranged inside a lateral hole, it is important that the piston motion sensor, and thus the transmitting and / or receiving unit for high-frequency radiation (or other sensor signal), is arranged both at a defined position inside the lateral hole representing the axial position of the piston motion sensor along the longitudinal axis of the lateral hole and at a defined position representing the rotational position of the piston motion sensor around the longitudinal axis of the lateral hole and thus the radiation direction of the signal of the piston motion sensor.

[0023] The embodiments known from the prior art lead to increased production efforts on the one hand with regard to manufacturing tolerances and increased installation efforts of the piston motion sensor in the transverse bore of the cylinder head on the other hand. Also, the piston motion sensor, in particular the sensor housing of different dimensions, may have to be manufactured according to the prior art in a series of piston-cylinder units of different dimensions (in particular different diameters of the cylinder tube and thus dimensions of the cylinder head), because the different dimensions of the piston-cylinder units lead to different distances between the sensor signal channel in the cylinder head and the connector plug on the outer surface of the cylinder head, which requires different lengths of the sensor housing.

[0024] The invention proposes that a positioning and / or alignment part can be used in this tension region. The positioning and / or alignment part ensures the correct positioning of the piston motion sensor in the axial longitudinal direction of the cross-hole. This ensures that the high-frequency signal of the piston motion sensor passes through the sensor signal channel, any collimator and the pressure chamber in the correct position and / or hits the end face of the piston or the piston rod in the correct position. Alternatively or additionally, the positioning and / or alignment part can also be used to predetermine the position of the piston motion sensor. If the positioning and / or alignment part is additionally used for the positioning and alignment of the piston motion sensor, deviations in the position and alignment of the high-frequency signal transmitted by the piston motion sensor are simply and reliably ensured within a predefined small tolerance range.

[0025] In the present invention, the positioning and / or alignment feature is arranged inside the transverse hole and is supported inside the transverse hole in the direction of the longitudinal axis of the transverse hole, i.e. in the installation direction. This support can be provided, for example, on the side, inclined surface, step, taper or annular collar of the transverse hole. The positioning and / or alignment feature has a defined axial position inside the transverse hole, which can be predetermined during the manufacture of the transverse hole, i.e. during the manufacture of the side, inclined surface, step, taper or annular collar.

[0026] The piston motion sensor is supported on top of the positioning and / or alignment part in the direction of the longitudinal axis. Since the positioning and / or alignment part has a defined axial position within the transverse bore, supporting the piston motion sensor on the positioning and / or alignment part ensures that the piston motion sensor also has a defined position within the transverse bore.

[0027] When using the same piston motion sensor for piston-cylinder units of different dimensions, the advantage is that the same piston motion sensor can be used for the different piston-cylinder units, but the predetermined position of the piston motion sensor inside the transverse bore is adjusted by positioning and / or alignment parts of different lengths.

[0028] As mentioned above, the support of the positioning and / or alignment part can be ensured by any side surface, inclined surface, step, taper or annular collar of the cross hole, etc. In a particularly simple proposal of the invention, the cross hole can be formed as a blind hole and the positioning and / or alignment part can be supported at the bottom of the blind hole (in particular at the edge region of the conical bottom). In this case, the position of the positioning and / or alignment part and thus also the position of the piston motion sensor can be predetermined by the depth of the blind hole.

[0029] It is also possible for the alignment of the positioning and / or alignment part around the longitudinal axis of the transverse hole to be pre-determined. This can be achieved, for example, by a form-fit between a cross-section of the housing of the positioning and / or alignment part and the transverse hole. For example, the transverse hole can have a groove or recess (or rib or protrusion) extending in the direction of the longitudinal axis and fitting in a form-fitting manner with a rib or protrusion (or groove or recess) of the housing of the positioning and / or alignment part. However, the alignment of the positioning and / or alignment part can also be ensured by having an eccentric recess (or protrusion) on the end face of the housing of the positioning and / or alignment part facing the bottom of the transverse hole, which engages in a corresponding protrusion (or recess) of the bottom.

[0030] A further aspect of the invention is aimed at fixing the positioning and / or alignment part inside the transverse hole. It is proposed to provide at least one fixing part. The fixing part serves to fix the longitudinal position of the positioning and / or alignment part inside the transverse hole. The fixing part therefore serves to ensure that both the positioning and / or alignment part and the piston motion sensor are in position and continue to operate. Alternatively or cumulatively, it is also possible to use at least one fixing part to fix the alignment of the positioning and / or alignment part about the longitudinal axis of the transverse hole (and therefore also the alignment of the piston motion sensor in certain circumstances).

[0031] There are various possibilities for the nature of the configuration of the fastening part. For example, a fastening bolt, a fastening split pin, a latch connection, a tongue and groove connection for fixing the alignment, etc. can be used. In a very simple embodiment, the fastening part is a screw. The screw can run parallel to the longitudinal axis of the transverse hole. For example, it is possible for the screw to run through the bottom of the blind hole and through the hole from the other side. However, it is also possible for the screw forming the fastening part to run radially with respect to the longitudinal axis of the transverse hole. In both cases, the screw is accessible from the outside of the cylinder head and runs through the hole to the positioning and / or alignment part, where it is fixed into the female thread of the positioning and / or alignment part. Furthermore, the positioning and / or alignment part can have both a surface-side screw hole, which is used when the screw runs parallel to the longitudinal axis of the transverse hole, and a radial screw hole for mounting when the screw runs radially with respect to the longitudinal axis of the transverse hole.

[0032] The positioning and / or alignment part and the piston motion sensor are preferably in direct contact with each other via contact surfaces, which can ensure a correct positioning of the piston motion sensor in the direction of the longitudinal axis of the transverse bore.

[0033] Not only does it have to be possible to predetermine the axial position of the piston motion sensor inside the transverse bore, but it may also have to predetermine the arrangement of the piston motion sensor with respect to the rotation angle around the longitudinal axis of the transverse bore. The rotation angle has to be predetermined, for example, so that the sensor signal emitted by the piston motion sensor passes through the sensor signal channel and / or strikes the end face of the piston or piston rod at a predefined point and / or in a predefined arrangement. This arrangement can be predetermined, for example, by the piston motion sensor interacting in a form-fitting manner in the circumferential direction with the transverse bore, on the one hand, the arrangement being predetermined by form-fitting, and on the other hand, the arrangement thus predetermined is consequently also maintained during operation. For example, the transverse bore may be provided with grooves extending in the direction of the longitudinal axis or recesses in which protrusions or ribs of the housing of the piston motion sensor are arranged. Conversely, it is also possible to provide ribs extending in the axial longitudinal direction of the transverse bore or protrusions which engage in grooves or recesses of the housing of the piston motion sensor. It is also possible for the cross bore on the one hand and the housing of the piston motion sensor on the other hand to have corresponding non-circular, for example elliptical, cross sections to ensure precise fit in the correct alignment.

[0034] In the present proposal, the contact surfaces of the positioning and / or alignment part on the one hand and the piston motion sensor on the other hand are connected to each other via a form-fit around the longitudinal axis of the transverse bore. This form-fit limits and even predetermines the relative alignment of the piston motion sensor on the one hand and the positioning and / or alignment part on the other hand, hereinafter referred to as the contact part. There are various possibilities for this form-fit. To give some non-limiting examples, one of the two contact parts can be provided with a protrusion that engages in a recess of the other contact part. Also, the end face of the contact part can be provided with a step that interacts in a form-fitting manner with a corresponding step of the other contact part to ensure anti-twisting and predetermination of the alignment.

[0035] A further aspect of the invention is aimed at enabling the removal of the piston motion sensor. This can be done, for example, for maintenance purposes, in case of failure of the piston motion sensor, for cleaning purposes or for the use of another piston motion sensor with a different measuring range or different measuring accuracy. In this case, the piston motion sensor is preferably held removably from the positioning part and / or alignment part, but still with a constant holding force ensured by the connection. For removal, preferably only a removal force has to be applied which exceeds the holding force threshold of the connection.

[0036] In one configuration of the invention, the piston motion sensor is connected to the positioning and / or alignment feature via a latch connection, where the latching force of the latch connection predetermines the retention force threshold, and when an installer applies a removal force to the piston motion sensor that is greater than the latching force, the latch connection is released and the piston motion sensor is removed from the positioning and / or alignment feature and removed from the cross hole.

[0037] In another embodiment, a permanent magnet is used between the piston motion sensor and the positioning and / or alignment part to generate a magnetic force as the holding force. In this case, the threshold value of the holding force is predetermined by the magnetic force required for removal. Within the scope of the present invention, it is also possible that a permanent magnet is provided in each of the piston motion sensor and the positioning and / or alignment part, and a magnetic force is generated between them.

[0038] The installer can apply the necessary removal force for removal in any way. In one proposal of the invention, the piston motion sensor has a removal catch in the area of ​​the face side remote from the positioning and / or alignment part. The removal catch can be connected to a removal tool. The force required for removal can be applied to the piston motion sensor via the removal tool and the removal catch. For example, the removal catch can be designed as a kind of hook connection on which a counter hook removal tool is hooked, the removal catch and the removal tool can form a latch connection, or the removal catch and the removal tool can be connected to each other via a permanent magnet.

[0039] In a particular proposal of the invention, the removal fastener is an internal thread of the piston motion sensor, into which a removal rod can then be screwed and through which the removal rod protrudes from the transverse hole after screwing, the required removal force can be applied to the piston motion sensor.

[0040] The female thread can be formed from the solid material of the sensor housing. In one proposal of the invention, the female thread is formed by an insert part with a female thread. This insert part with a female thread is embedded inside the sensor housing of the piston motion sensor or pressed inside a bore of the sensor housing. The use of such an insert part with a female thread is advantageous, for example, if the sensor housing is made of a material that does not provide the necessary strength for the production of the female thread. In this case, a stronger material, in particular a metal, can be selected as the material of the insert part with a female thread. A stronger material can provide the necessary strength for the screw connection in the screwed area. On the other hand, the insert part with a female thread can have an enlarged outer surface, which allows a large-area connection to the sensor housing and power transmission.

[0041] In principle, the connector plug can be formed directly by the sensor housing or can be held on the sensor housing and project outward from the cross bore and the cylinder head, where the connector plug can be connected to the required connection cable. In one proposal of the invention, the piston motion sensor is connected to the housing plug via a sensor cable. The sensor unit thus has two subunits, the piston motion sensor and the housing plug, which are flexibly connected to each other via the sensor cable. The connection via the sensor cable allows the sensor cable to be installed with some bending and stretching to suit different installation situations, so that it is easily possible to adapt to the use of the same piston motion sensor and the same housing plug for piston-cylinder units of different dimensions. On the other hand, in certain situations, the sensor housing does not have to be connected in a suspended manner over the entire radial area from the actual measuring area to the connection plug, but rather can be made more rigid or shorter, since a partial area can be connected in a suspended manner by the sensor cable.

[0042] It is particularly preferred if the sensor cable is removably connected to the piston motion sensor and / or the housing plug, which makes it possible, for example, to first install only the piston motion sensor separately, then connect the sensor cable and finally install the housing plug, with the corresponding removal also being performed separately. Furthermore, for example, for maintenance purposes or in the case of a breakdown, only the piston motion sensor or the housing plug has to be replaced, while the remaining parts of the piston motion sensor and the housing plug can still potentially be used.

[0043] However, in a particular proposal of the present invention, the releasable connection to the sensor cable also makes it possible for the same piston motion sensor to be used with different housing plugs in order to allow adaptation to different applications requiring different housing plugs.

[0044] It is also preferred that the housing plug is removably connected to the cylinder head. In one proposal of the invention, the housing plug is provided with a flange for this purpose. The flange can be screwed into the cylinder head and allows a secure connection between the housing plug and the cylinder head. The flange can be screwed into the cylinder head with different alignment arrangements of the housing plug in the transverse bore relative to the center of the longitudinal axis, so that the respective installation conditions can be taken into account.

[0045] Any different housing plugs can be used within the scope of the present invention. On the one hand, the housing plugs can have different shapes. The first housing plug is formed in a straight line, while the second housing plug usable within the scope of the present invention can be designed in an L-shape. In this case, the housing plug comprises a support having two angles. In this case, one support extends inside the transverse bore of the cylinder head. In this case, the sensor cable can be connected to the end side area of ​​this support. In contrast, the other support extends outside the cylinder head. This support can extend radially with respect to the longitudinal axis of the transverse bore. In the installation situation, the support is oriented parallel to the longitudinal central axis of the cylinder of the piston-cylinder unit, which is preferred in some applications. In this case, the end side of the latter support can be used to connect the connection cable.

[0046] In addition to using housing plugs of different shapes in the piston-cylinder unit according to the invention, the housing plugs can alternatively or cumulatively be provided with different connection shapes and pin configurations.

[0047] a) For example, it is possible for the housing plug of the first type to be designed as a so-called DIN plug. For example, this is an M12 DIN plug, which can be designed with 5 pins. Such DIN plugs are described in the standards DIN 41524 (3-pin and 5-pin), DIN 45322 (5 pins at 60° intervals), DIN 45326 (8 pins) and DIN 45329 (7 pins) (these standards have been replaced by EN 60130-9). Various subtypes of this housing plug of the first type are available which have different configurations of the contact pins.

[0048] aa) In the first subtype, the first pin is unassigned, the second pin is assigned to the VDC function (voltage supply of the piston motion sensor), the third pin is assigned to the GND (ground) function, the fourth pin is assigned to the CAN HI data bus and the fifth pin is assigned to the CAN LO data bus.

[0049] ab) In the second subtype of the first type, the first pin may be unassigned, the second pin may be assigned to VDC, the third pin may be assigned to GND, the fourth pin may be assigned to a pulse width modulated signal, and the fifth pin may be unassigned.

[0050] b) In the case of the second type of housing plug, the housing plug is made as a so-called German plug (Deutsch-Stecker), e.g. the 4-pin German plug DT04.

[0051] ba) For example, the first subtype of the second type may be equipped with a first pin that provides a VDC function, a second pin that is assigned to a CAN LO function, a third pin that is assigned to a GND function and a fourth pin that is assigned to a CAN HI function.

[0052] bb) In contrast, in a second subtype of the second type, it is possible for the first pin to be assigned to a VDC function, the second pin to be assigned to a GND function, the third pin to be assigned to a PWM function, and the fourth pin to be unassigned.

[0053] According to the invention, depending on the requirements and intended application, it is possible to arbitrarily combine the same piston motion sensor with housing plugs of different shapes and angles of support of the housing plug and / or with housing plugs of the different types and subtypes mentioned above via a detachable sensor cable.

[0054] Preferred configurations of the invention are evident from the claims, the description and the drawings. The advantages of the features and combinations of features mentioned in the description are merely examples and may have alternative or cumulative effects, which advantages are not necessarily achieved by the embodiments according to the invention.

[0055] With regard to the disclosure (not the scope of protection) of the original application documents and the patent, the following is given: Further features result from the drawings, in particular from the illustrated shapes, the relative dimensions of the several components with respect to one another, and their relative arrangement and operative connection. Combinations of features of different embodiments of the invention or features of different claims are also possible and are suggested hereby, apart from selected backward references in the claims. This also applies to features shown in separate drawings or described in the description thereof. These features can also be combined with features of different claims. Similarly, features described in the claims can be omitted for further embodiments of the invention, but this does not apply to the independent claims of the granted patent.

[0056] Features described in the claims and description should be understood in the form of the presence of exactly the same number or more than the number described, without the need to explicitly use the adverb "at least". For example, when speaking of one element, this should be understood to mean that there is exactly one element, two elements, or more parts. Features described in the claims may be supplemented by further features or may be the only features possessed by the subject matter of the respective claim. Reference numbers contained in the claims do not limit the scope of the subject matter protected by the claims. They are used only to facilitate the understanding of the claims. [Brief description of the drawings]

[0057] The invention will now be further described with reference to preferred embodiments illustrated in the drawings. [Figure 1] 1 shows a longitudinal section of a piston-cylinder unit according to the prior art; [Diagram 2] 3 is a partial longitudinal section through a piston-cylinder unit in the region of the cylinder head. [Diagram 3] FIG. 3 is a spatially exploded view of the cylinder head of FIG. 2 with its assigned structural parts. [Figure 4] FIG. 13 is a spatially exploded view of the piston motion sensor and the positioning and / or alignment portion. [Diagram 5] FIG. 1 is a spatial view showing a housing plug of the DIN plug (5 pin) type equipped with a sensor cable. [Figure 6] FIG. 6 is a side view of the housing plug with the sensor cable of FIG. 5. [Figure 7] FIG. 1 is a spatial diagram showing a German plug (4 pin) type housing plug equipped with a sensor cable. [Figure 8] FIG. 8 is a side view of the housing plug of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] Unless anything different emerges from the following text, the above explanations regarding the prior art and the embodiment of FIG. 1 can be applied accordingly to the embodiments of the present invention, and the further disclosures of DE 102019122121 A1 and EP 3957868 A1 can also be adopted within the framework of the present invention.

[0059] FIG. 2 shows the piston-cylinder unit 1 in the region of the cylinder head 4. The sensor signal channel 26 leads to the pressurized chamber 33 of the piston-cylinder unit 1. A collimator 35 is arranged in the sensor signal channel 26. The collimator 35 has a flat end face on the side facing the piston motion sensor 28, which is aligned perpendicular to the longitudinal center axis 30. The collimator 35 is formed rotationally symmetrical with respect to the longitudinal center axis 30. The collimator 35 has, for example, a curved, in particular parabolic, longitudinal cross section, as shown. The collimator 35 has a ring groove 36, in which an O-ring 38 is arranged as a seal 37. The seal 37 ensures the tightness (sealability) of the hydraulic part between the inner wall of the sensor signal channel 26 and the collimator 35. The sensor signal channel 26 also has a circumferential corner 39. When the pressurizing chamber 33 is hydraulically pressurized, pressure is generated by the hydraulic pressure acting on the spherical end face facing the piston 7, and the collimator 35 is pressed against the corner 39. This pressing of the collimator 35 against the corner 39 and / or the effect of the seal 37 ensure that the lateral hole 27 is not pressurized by hydraulic fluid, and therefore no additional sealing measures need to be taken for the lateral hole 27. On the other hand, this seal allows the piston motion sensor 28 to be removed without hydraulic fluid leaking from the lateral hole 27.

[0060] As can be seen from the exploded view of Figure 3, a fixing part 40 in the form of a screw 41, a positioning and / or alignment part 42, the piston motion sensor 28, a sensor cable 43 and a housing plug 44 are attached to the transverse hole 27, and the housing plug 44 is fixed to a housing 46 in the cylinder head 4 via a fixing screw 45.

[0061] 4, the positioning and / or alignment part 42 is formed in a cylindrical shape having a diameter that allows the positioning and / or alignment part 42 to be inserted so as to fit snugly into the transverse hole 27. The lower surface of the positioning and / or alignment part 42 is formed flat in the illustrated exemplary embodiment. The lower surface of the positioning and / or alignment part 42 contacts the bottom 47 of the transverse hole 27, which is formed here as a blind hole.

[0062] The surface of the positioning and / or alignment part 42 facing the piston motion sensor 28 is essentially flat, but is formed with a step 48. This surface of the positioning and / or alignment part 42 is provided with a cylindrical receiving part 49 in which a permanent magnet 50 is accommodated, which can be glued or pressed into the receiving part 49. The outer surface of the permanent magnet 50 is arranged flush with the partial surface of the end face of the positioning and / or alignment part 42 remote from the step 48.

[0063] The side of the positioning and / or alignment part 42 away from the piston motion sensor 28 has an internal thread 51 arranged eccentrically with respect to the longitudinal axis 53 of the transverse bore. In the positioned position of the positioning and / or alignment part 42 installed in the transverse bore 27, the internal thread 51 of the positioning and / or alignment part 42 opens into the transverse bore 27 and the thread 41 is aligned with a hole 52 extending from the outside of the housing 46. In this way, the positioning and / or alignment part 42 is fixed in the correct position and relative position.

[0064] The positioning and / or alignment part 42 also has a transverse hole 54, which may be provided with an internal thread. If the hole 52 oriented parallel to the longitudinal axis 53 of the transverse hole is not present or is not used, as shown in FIG. 2, and a hole oriented perpendicular to the drawing plane of FIG. 2 is provided in the housing 46, then, as an alternative to the fixing by the screw 41, the fixing of the positioning and / or alignment part 42 can be performed by a screw extending perpendicular to the drawing plane of FIG. 2 through the housing 46 and screwed inside the transverse hole 54 of the positioning and / or alignment part 42.

[0065] The piston motion sensor 28 has a sensor housing 55, which has a cylindrical outer shape and a diameter such that the sensor housing 55 fits snugly into the cross hole 27. Compared to this outer shape, the sensor housing 25 has a recess in which area the electronic unit and the unit for transmitting and / or receiving high-frequency signals are arranged.

[0066] On the side of the sensor housing 55 facing the positioning and / or alignment part 42 there is a step 56, which is formed corresponding to the step 48 of the positioning and / or alignment part 42. At a position away from the step 48 and the step 56 the positioning and / or alignment part 42 and the sensor housing 55 form contact surfaces 57 and 58, which are arranged side by side transversely to the longitudinal axis 53 and abut each other, whereby the axial position of the piston motion sensor 28 is predetermined.

[0067] In contrast, the steps 48 and 56 form a form-fit with respect to the direction of rotation about the longitudinal axis 53, which predetermines the position of the piston motion sensor 28. In the relative position predetermined by the steps 48 and 56, a corresponding receiving portion 59 with a permanent magnet 60 is provided in the sensor housing 55 alongside the receiving portion 49 and the permanent magnet 50 of the positioning and / or alignment portion 42. The permanent magnet 60 is also fixed in the receiving portion 59, for example by gluing or press-fitting. The magnetic force between the permanent magnets 50 and 60 fixes the contact and thus the position and positional relationship between the positioning and / or alignment portion 42 and the piston motion sensor 28.

[0068] On the side of the sensor housing 55 facing away from the positioning and / or alignment part 42, the sensor housing 55 has a flat end face 61. In the region of this end face 61, the piston motion sensor 28 has an internal thread 62 formed by an insert part 63 having an internal thread, which is injected into the sensor housing 55 and is formed by the insert part 63 having an internal thread. The internal thread 62 forms a breakaway fastener 64.

[0069] Furthermore, the end face 61 is provided with a plug receptacle 65 into which a plug 66 of the sensor cable 43 can be plugged. The plug 66 and the plug receptacle 65 are preferably in the form of a 5-pin Pico-Clasp® connection. Figures 5 and 6 show the housing plug 44-I, where "I" indicates that this is a first type of housing plug (see above for the first type).

[0070] As can be seen from Fig. 6, the housing plug 44-I is formed in an L-shape, with support parts 67 and 68 bent at a 90 degree angle here. A plug receptacle is provided on the end side of the support part 68, into which a sensor cable plug 69 of the sensor cable 43 can be inserted. Both the plug receptacle and the sensor cable plug 69 are preferably of the "Pico-Clasp" type.

[0071] The outer end region of the support 68 extends coaxially with the longitudinal axis 53 of the transverse bore. The outer end region of the support 68 may be provided with an annular bead 70 or a seal. When inserted in the transverse bore 27, the annular bead 70 frictionally engages the support 68 in the transverse bore 27 and provides an elastic prestressed fixation. Furthermore, a seal can also be provided here.

[0072] In the area of ​​the exit of the support 68 from the housing 46 of the cylinder head 4, the support 68 has a flange 71, here circumferential. The flange 71 is received in a corresponding receiver or recess in the housing 46. The flange 71 has a through hole oriented parallel to the longitudinal axis 53, through which the flange 71 can be screwed into a corresponding threaded hole in the housing 46. Preferably, a number of through holes are provided in the flange 71 and a threaded hole is provided on the inside of the housing 46, so that the housing plug 44-I can be screwed into the housing 46 at different positions around the longitudinal axis 53.

[0073] The end region of the support 67 forms the connector plug 34, which allows the connection of a connector cable. In the case of the housing plug 44-I, the connector plug 34 has five pins 72, as shown in particular in Fig. 5. In particular, this is a connector plug 34 of the "DIN connector plug M12 5 pin" type. Here, the housing plug 44-I of the first type can be formed according to the subtypes described above.

[0074] 7 and 8 show a housing plug 44-II, where "II" indicates a second type of housing plug, which may be formed according to the subtypes described above.

[0075] The housing plug 44 incorporates an electronic arrangement for modifying the signal transmitted from the sensor cable plug 69 to the connector plug 34, respectively. The piston motion sensor 28 directly measures the stroke of the piston 7 or piston rod 8 in the piston-cylinder unit 1. The piston motion sensor 28 is preferably based on a non-contact measuring radar system, which analyses the travel time of the reflected signal back to the transmitting unit, the end face of the piston 7 or piston rod 8 and the receiving unit. From the travel time the position and / or velocity can then be determined with high precision and robustness.

[0076] The piston-cylinder unit 1 is formed with a piston motion sensor 28, preferably complying with the IP69K protection class. The piston motion sensor 28 can detect strokes in the range of 10 mm to 2,000 mm, for example 30 mm to 1,800 mm or 40 mm to 1,600 mm. Here, a resolution in the range of 0.2 mm to 4 mm, for example 0.5 mm to 2 mm or 0.8 mm to 1.5 mm, can be realized.

[0077] Further, an advantage of sealing the sensor signal channel 26 with a sealing portion or collimator 35 is that the piston motion sensor 28, the sensor housing 55, and the electronic configuration of the piston motion sensor 28 are not deformed, stressed, or damaged by high hydraulic pressures, which can be from 100 bar to 600 bar.

[0078] The sensor cable 43 and the Pico Clasp plug used to connect the piston motion sensor 28 to the housing plug 44 can have five pins and can be assigned GND, VDC, CAN LO, CAN HI and an analog signal. The analog signal can be used to transmit a pulse width modulated signal (PWM) and the measurement signal is transmitted via pulse width modulation. Alternatively, it is also possible to transmit a voltage or current proportional to the measurement signal as an analog signal.

[0079] In some circumstances, the piston motion sensor 28 can measure, transmit and / or analyze not only the stroke and / or speed of the piston 7 or piston rod 8 but also other measurement variables, such as temperature, which can be used for temperature compensation.

[0080] Also, bidirectional transmission is possible via the housing plug 44, which allows software updates of the piston motion sensor 28 to be performed and update functions to be performed. If a PWM signal is transmitted, its frequency is preferably 500 Hz. The duty cycle provides information about the measurement path of the piston 7. When the piston 7 is fully retracted, the duty cycle is for example 5%, when the piston 7 is fully extended, the duty cycle is 95%. [Explanation of symbols]

[0081] 1 Piston Cylinder Unit 2 Cylinder 3. Interior space 4. Cylinder head 5 Bearing bush 6 Connectors 7 Piston 8 Piston rod 9 Piston rod eye 10 Bearing bush 11 Guide bush 12 Rod seal 13 O-ring 14 Support Ring 15 O-ring 16 Wiper 17 Slide bearing 18 Fixing nut 19 O-ring 20 Piston guide ring 21 Piston seal 22 Piston guide ring 23 Welded seams 24 Connectors 25 Sub-chamber 26 sensor signal channels 27 Side Cave 28 Piston Motion Sensor 29 Hydraulic Fluids 30 (cylinder) longitudinal center axis 31 Cylinder tube 32 Pressurized chamber 33 Pressurized chamber 34 Connector plug 35 Collimator 36 Ring groove 37 Seal part 38 O-ring 39 Corner 40 Fixed part 41 Screw 42 Positioning and / or alignment section 43 Sensor cable 44 Housing plug 45 Fixing screw 46 Housing 47 Bottom 48 Steps 49 Receiving part 50 Permanent Magnets 51 Female thread 52 holes 53 (of the side hole) longitudinal axis 54 Side Cave 55 Sensor housing 56 Steps 57 Contact surface 58 Contact surface 59 Receiving part 60 Permanent Magnets 61 End face 62 Female thread 63 Threaded Insert 64 Removal fastener 65 Plug receiving part 66 Sensor cable plug 67 Support part 68 Support part 69 Sensor cable plug 70 Annular Bead 71 Flange 72 pin

Claims

1. A piston-cylinder unit, a cylinder including a cylinder head; a piston that is pressurized by a pressurized fluid through a pressurizing chamber and is movable in an axial direction within a cylinder; a piston motion sensor; The piston motion sensor is disposed within a lateral bore of the cylinder head having a longitudinal axis; generating a sensor signal which is transmitted through the pressurizing chamber to the piston or piston rod, reflected by the piston or piston rod, and transmitted again through the pressurizing chamber to the piston motion sensor; A piston and cylinder unit, wherein the side hole is fluidly separated from the pressurizing chamber.

2. 2. The piston and cylinder unit according to claim 1, wherein the side hole is fluidically separated from the pressurizing chamber via a seal portion.

3. The sensor signal is transmitted from the piston motion sensor to the pressurizing chamber via a dielectric lens or a collimator; and / or a signal is transmitted from the pressure chamber to the piston motion sensor after being reflected by the piston or the piston rod; the dielectric lens or the collimator is disposed inside a sensor signal channel; 3. The piston-cylinder unit according to claim 2, wherein the seal portion is disposed between the dielectric lens or the collimator and the sensor signal channel.

4. the positioning and / or alignment feature is supported within the transverse hole along the longitudinal axis of the transverse hole; 4. A piston-cylinder unit according to claim 1, characterized in that the piston motion sensor is supported above the direction of the longitudinal axis of the positioning and / or alignment part.

5. The lateral hole is a non-through hole, 5. The piston cylinder unit according to claim 4, characterized in that the positioning and / or alignment portion is supported by a bottom of the blind hole.

6. the position of the positioning and / or alignment portion in the direction of the longitudinal axis of the transverse hole, and / or the alignment of the positioning and / or alignment portion around the longitudinal axis in the transverse hole is fixed by at least one fixing portion; 6. A piston-cylinder unit as claimed in claim 4 or 5, characterized in that the fixing portion is preferably a screw extending parallel to the longitudinal axis of the transverse hole or extending radially with respect to the longitudinal axis of the transverse hole.

7. the positioning and / or alignment unit and the piston motion sensor are in contact with each other via a contact surface; 7. A piston-cylinder unit as claimed in claim 4, wherein the contact surface limits or predetermines the alignment of the piston motion sensor relative to the positioning and / or alignment portion via a circumferential form-fit around the longitudinal axis of the transverse hole.

8. 8. A piston-cylinder unit according to claim 4, wherein the piston motion sensor is held on the positioning and / or alignment part via a latch connection or a permanent magnet.

9. the piston motion sensor has a removal fastener on a side remote from the positioning and / or alignment portion connectable to a removal tool for applying a removal force to the piston motion sensor to remove the piston motion sensor from the positioning and / or alignment portion; The removal fastener is preferably formed as an internal thread of the piston motion sensor; 9. A piston-cylinder unit according to claim 4, characterized in that the female thread is formed in particular by an insert part with a female thread which is injected or pressed into a sensor housing of the piston motion sensor.

10. the piston motion sensor is connected to a housing plug via a sensor cable; 10. The piston cylinder unit according to claim 1, wherein the sensor cable is detachably connected to the piston motion sensor and / or to the housing plug.

11. 11. The piston and cylinder unit according to claim 10, wherein the housing plug is detachably connected to the cylinder head.

12. The housing plug has a flange.

12. The piston and cylinder unit according to claim 11, wherein the flange is screwed to the cylinder head.

13. 13. A piston and cylinder unit as claimed in claim 12, characterized in that the flange is screwable to the cylinder head with different alignment arrangements of the housing plug relative to the centre of the longitudinal axis of the transverse bore.

14. The housing plug is formed in an L-shape including two angled supports; One of the angled support portions extends to an inside of the transverse hole of the cylinder head, 14. A piston and cylinder unit as claimed in any one of claims 10 to 13, characterized in that the other angled support extends outside the cylinder head. Preferably

15. 15. Piston-cylinder unit according to claim 10, characterized in that the housing plug is designed as a DIN plug or a German plug.

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