PISTON-CYLINDER UNIT, SET WITH ONE PISTON-CYLINDER UNIT AND GROUP OF PISTON-CYLINDER UNITS

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a piston-cylinder unit. The piston-cylinder unit can be used in a work machine (in particular a construction machine, an agricultural machine, a maritime machine, a wheel loader, an excavator, a dump truck, a crane, a forklift, a lifting platform, or another work machine that is used in a known manner in mechanical engineering). The piston-cylinder unit can serve, for example, to steer, support, extend, tilt, lift, lower, or otherwise move a part of the work machine (in particular a tool, a swing arm, or another part of the work machine). It is preferably a hydraulic piston-cylinder unit.

[0002] Furthermore, the invention relates to a set with a piston-cylinder unit, whereby this set can also be used for a work machine.

[0003] Finally, the invention relates to a group of piston-cylinder units, wherein the group comprises different subgroups, and the piston-cylinder units of the different subgroups are designed and intended for different purposes. Such a group of piston-cylinder units can, for example, be manufactured, offered, and distributed by a manufacturer for the different purposes, or offered and distributed by a sales company, or stocked and / or used by a customer for the different purposes. STATE OF THE ART

[0004] A piston-cylinder unit of this type is known from the publication DE 10 2019 122 121 A1. This known piston-cylinder unit is Fig. 1 shown. In Fig. 1It is indicated by means of break lines that the piston-cylinder unit 1 can actually be longer and only a part of it is shown. The piston-cylinder unit 1 has 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 weld seam 23. A bearing bush 5 is arranged in the area of ​​the cylinder head 4. DE 10 2019 122 121 A1 relates to a hydraulic piston-cylinder unit 1, so that the interior space 3 is filled with a hydraulic fluid 29, in particular oil. For this purpose, the cylinder 2 has a connection 6 and a connection 24. A hydraulic circuit (not shown here) with a hydraulic pump and changeover valves is connected to the connections 6, 24. The connections 6, 24 each open into an associated pressure chamber 32, 33.The pressure chambers 32, 33 are formed in the interior 3 and separated from one another by a piston 7. The piston 7 is displaceable along the longitudinal center axis 30 of the cylinder 2 while sealing the pressure chambers 32, 33. Depending on the pressure generated by the hydraulic circuit at the connections 6, 24, an actuating force can be hydraulically generated in both directions along the longitudinal center axis 30, which acts on the piston 7, and the actuating movement of the piston 7 generated thereby can bring about a change in the volume of the pressure chambers 32, 33. Fig. 1shows the position of the piston 7 moved all the way 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 bushes 5, 10 serve to link the piston-cylinder unit 1 to the parts of the work machine which are to be moved relative to one another by means of the piston-cylinder unit 1 and / or on which the piston-cylinder unit 1 is to exert a force. The piston rod 8 is mounted by means of a guide bush 11 so that it can be moved translationally in the axial direction 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 axial end of the guide bush 11, another O-ring 15, a wiper 16 and a plain bearing 17 are arranged.The piston 7 is arranged on the piston rod 8 in a rotationally fixed manner and secured by means of a lock 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, together with the piston rod 8 and the piston rod eye 9, is mounted in a translationally reciprocating, sealing manner in the cylinder tube 31 of the cylinder 2. The part of the pressure chamber 33 that is delimited by the cylinder tube 31 is adjoined by a subchamber 25 of the pressure chamber 33 in the cylinder head 4. The subchamber 25 is connected to the connection 24. An axially extending sensor signal channel 26 opens into this subchamber 25. The sensor signal channel 26 is also part of the pressure chamber 33 and is therefore filled with the hydraulic fluid. The sensor signal channel 26 is in turn connected to a transverse bore 27 extending radially to the longitudinal center axis 30 in the cylinder head 4.The transverse bore 27 extends to the outer surface of the cylinder head 4 and can be connected to the environment by means of a compensating bore (not shown). A piston movement sensor 28 is arranged in the transverse bore 27. The piston movement sensor 28 is used to detect the axial position of the piston 7 in the cylinder 2 using high-frequency technology. For this purpose, the piston movement sensor 28 sends out a high-frequency signal which passes through the sensor signal channel 26 and through the partial chamber 25 as well as through the pressure chamber 33 onto the end face of the piston 7 or the piston rod 8 and, after being reflected by this end face, returns to the piston movement sensor 28. The movement signal, in particular the distance traveled by the end face, can then be determined from the reflected signal using high-frequency technology, in particular by evaluating the propagation time. For the device shown in . Fig. 1In the illustrated embodiment, the piston movement sensor 28 is pressurized with hydraulic fluid. A sensor housing of the piston movement sensor 28 has seals with which the piston movement sensor 28 is sealed axially on both sides of the sensor signal channel 26 so that the hydraulic fluid cannot escape from the pressure chamber 33 and via the transverse bore 27. The piston movement sensor 28 here has a connector plug 34, which is carried by the sensor housing of the piston movement sensor 28 and extends radially out of the cylinder head 4. For further details, reference is made to the document DE 10 2019 122 121 A1.

[0005] A further development of this piston-cylinder unit 1 is known from document EP 3 957 868 A1. It is proposed here that a collimator be arranged in the beam path for the high-frequency signal, which serves to increase the measurement accuracy of the piston movement sensor. A collimator is understood to be an optical device for generating a beam path with parallel beams from previously non-parallel beams from divergent sources. In a first radiation direction from a transmitter unit of the piston movement sensor to the end face of the piston or piston rod, the collimator converts the non-parallel beams emitted by the piston movement sensor into parallel beams, which are then also reflected in parallel from the end face of the piston or piston rod.The reflected high-frequency rays are then bundled again by the collimator in the opposite second radiation direction so that they can be received and evaluated by a receiving unit of the piston movement sensor. The collimator can also act as a type of filter, focusing only or primarily those high-frequency rays onto the piston movement sensor that were previously parallel to each other and to the longitudinal axis of the piston. This allows high-frequency rays that do not originate, or at least not directly, from the end surface of the piston crown to be filtered out. Such unwanted rays are due to the fact that in reality the refraction of the collimator is not ideal, the rays are not ideally emitted and received as a point, and the piston crown surface is not ideally flat. The use of the collimator is intended to improve the signal-to-noise ratio.The collimator can have a dielectric lens. It is also possible to use multiple dielectric lenses or a Fresnel zone plate. The dielectric lens can have a convex lens surface and / or be made of or comprise a dielectric plastic or dielectric ceramic, polytetrafluoroethylene, polyethylene, or polypropylene. The dielectric lens preferably has a dielectric constant (permittivity) that is greater than that of air and greater than that of the hydraulic fluid in the piston-cylinder unit. The permittivity can, for example, be between 20% and 50% greater than that of the hydraulic fluid in the piston-cylinder unit. The permittivity difference and the curvature of the dielectric lens are coordinated. The dielectric lens can have a planar-convex lens shape. The convex side of the lens can face the piston.In contrast, the planar side then faces the piston movement sensor. The collimator can be formed from the sensor housing or structurally separate from the piston movement sensor itself and the sensor housing. The piston movement sensor can also be designed as a compact built-in cartridge that contains both the sensor and the evaluation electronics. The piston movement sensor is arranged in the transverse bore with an orientation such that the longest dimension of the piston movement sensor extends in the direction of the longitudinal axis of the transverse bore. Beam deflection elements can be arranged at a bottom of the sub-chamber away from the sensor signal channel to prevent falsification of the measurement results. The collimator can be arranged in the sensor signal channel. For further details, reference is made to document EP 3 957 868 A1.

[0006] The non-generic publications DE 20 2019 101 788 U1, US 2019 / 0296504 A1, and US 6,725,761 B1 disclose piston-cylinder units in which a cylinder head has a longitudinal bore opening into the pressure chamber, into which a piston motion sensor is inserted from the side of the pressure chamber. The piston motion sensor is designed here as a magnetostrictive sensor with a rod-shaped magnetostrictive sensor element extending along the longitudinal axis of the cylinder and through the piston and a piston rod, and a magnet that moves with the piston. OBJECT OF THE INVENTION

[0007] The present invention is based on the object of proposing a piston-cylinder unit with a piston movement sensor integrated in the cylinder head, which is particularly suitable with regard to the connection options and / or the variety of components and / or the assembly and / or disassembly effort and / or the variability of the operating conditions and the connection conditions to the work machine is improved.

[0008] Furthermore, the invention is based on the object of proposing a set with a piston-cylinder unit which can be used for the use of the piston-cylinder unit for different purposes.

[0009] Finally, the invention is based on the object of proposing a group of piston-cylinder units in which two subgroups are designed and intended for different purposes, but nevertheless there is a small variety of components. SOLUTION

[0010] The object of the invention is achieved by the features of the independent patent claim. Further preferred embodiments of the invention can be found in the dependent patent claims. DESCRIPTION OF THE INVENTION

[0011] The invention proposes a piston-cylinder unit comprising a cylinder with a cylinder head, a piston axially movable within the cylinder, and a piston motion sensor. The piston motion sensor is arranged in a transverse bore of the cylinder head having a longitudinal axis.

[0012] The invention is based in particular on the finding that, according to the prior art (cf. also the prior art cited above), the piston motion sensor has a housing that extends up to and out of the outer surface of the piston-cylinder unit. A connector is held on the housing of the piston motion sensor in the freely accessible end region, which connector extends radially outward from the cylinder head relative to the longitudinal center axis of the cylinder. In contrast, according to the invention, the piston motion sensor is connected to a housing connector via a sensor cable.

[0013] The sensor unit thus comprises two sub-units: the piston movement sensor and the housing connector, which are flexibly connected via the sensor cable. The connection via the sensor cable enables easy adaptation for the use of the same piston movement sensor and the same housing connector for piston-cylinder units with different dimensions, as the sensor cable can be installed with a more or less curved or straight design for different installation situations. On the other hand, the sensor housing can be designed to be less rigid or shorter under certain circumstances, since the sensor housing does not have to bridge the entire radial area from the actual measuring range to the connector, but rather a partial area can be bridged by the sensor cable.

[0014] Furthermore, according to the invention, the sensor cable is detachably connected to the piston movement sensor and / or the housing connector. This allows, for example, separate assembly first of only the piston movement sensor, then the connection of the sensor cable, and finally the assembly of the housing connector, whereby a corresponding separate disassembly can also take place. Furthermore, it is possible that, for example for maintenance purposes or in the event of a defect, only one piston movement sensor or one housing connector needs to be replaced, while the remaining part of the piston movement sensor and the housing connector can then continue to be used. However, the detachable connection to the sensor cable also makes it possible for the same piston movement sensor to be used with different housing connectors in order to adapt it to different applications that require different housing connectors.It is possible for any number of different housing connectors to be used within the scope of the invention. For example, the housing connectors can have different shapes. It is possible for a first housing connector to be linear, while a second housing connector usable within the scope of the invention is L-shaped. The L-shaped housing connector according to the invention has two angled legs.

[0015] One leg then extends into the interior of the cylinder head's transverse bore. The sensor cable can then be connected to the end face of this leg. The other leg, however, extends outward from the cylinder head. This leg can extend radially to the longitudinal axis of the transverse bore. For one installation situation, the leg is oriented parallel to the longitudinal center axis of the cylinder of the piston-cylinder unit, which is advantageous for some applications. In this case, the end face of the latter leg serves to connect a connecting cable.This embodiment is based in particular on the finding that a plug aligned radially to the longitudinal center axis of the cylinder and attached directly to the housing of the piston movement sensor, as used according to DE 10 2019 122 121 A1 or EP 3 957 868 A1, is disadvantageous because a connecting cable connected to this plug, when used in the work machine, usually does not run radially to the longitudinal center axis of the cylinder, but rather, for example, parallel to the longitudinal center axis. This leads to a kink in the connecting cable immediately adjacent to the plug, which can lead to damage to the connecting cable. According to the prior art, a remedy in such a case is provided by mounting an intermediate plug on the plug, which then forms a plug receptacle into which the connecting cable can be plugged in a direction parallel to the longitudinal center axis of the cylinder.However, the intermediate plug represents an undesirable additional component whose reliable contact conditions must be guaranteed even under the harsh operating conditions prevailing in the tool. The housing plug, with one leg extending into the transverse bore and its connection to the sensor cable inside the transverse bore closed to the outside by the housing plug, provides a reliable solution here. It is also advantageous if the housing plug is detachably connected to the cylinder head. In one proposal of the invention, the housing plug has a flange for this purpose. The flange can then be screwed to the cylinder head, enabling a reliable connection between the housing plug and the cylinder head.

[0016] It is even possible for the flange to be screwed to the cylinder head in different orientations of the housing plug around the longitudinal axis of the cross bore, thus taking the respective installation conditions into account.

[0017] In the piston-cylinder unit according to the invention, the L-shaped housing connector can be equipped with different connection geometries and pin assignments. a) It is possible, for example, for a first type of housing connector to be designed as a so-called DIN connector. For example, it could be an M12 DIN connector, which can be 5-pin. Such DIN connectors are described in the standards DIN 41524 (3- and 5-pin), DIN 45322 (5-pin with 60° spacing), DIN 45326 (8-pin) and DIN 45329 (7-pin) (these standards replaced by EN 60130-9). For this first type of housing connector, different subtypes can then be used, which differ in the assignment of the connection pins: aa) For a first subtype, a first pin is not assigned. A second pin is assigned the VDC function (power supply for the piston movement sensor). A third pin is assigned the GND (ground) function. A fourth pin is assigned to the CAN HI data bus, while a fifth pin is assigned to a CAN LO data bus.ab) For a second subtype of the first type, a first pin can be unused, a second pin can be connected to VDC, a third pin can be connected to GND, a fourth pin can be connected to a pulse-width modulated signal, and a fifth pin can be unused. b) For a second type of housing connector, the housing connector is designed as a so-called Deutsch connector, which can be, for example, a Deutsch connector DT 04 with four pins.

[0018] Different subtypes are also possible for the second type: ba) For example, a first subtype of the second type may be equipped with a first pin that provides the VDC function. The second pin is assigned to the CAN LO function, a third pin to the GND function, and a fourth pin to the CAN HI function. bb) In contrast, for a second subtype of the second type, a first pin may be assigned to the VDC function, a second pin to the GND function, a third pin to the PWM function, and a fourth pin may be unassigned.

[0019] According to the invention, it is possible that one and the same piston movement sensor can be connected via the detachable sensor cable, depending on the requirements and intended use, either with

[0020] Housing connectors of the different types and subtypes mentioned can be combined.

[0021] A further embodiment of the invention utilizes the knowledge that for the required accuracy of the measurement results of the piston movement sensor arranged in the transverse bore, it is crucial that the piston movement sensor and thus the transmitting and / or receiving unit for the high-frequency radiation (or another sensor signal) both in the predetermined position in the transverse bore, which describes the axial position of the piston movement sensor along the longitudinal axis of the transverse bore, and in the predetermined orientation, which describes the rotational position of the piston movement sensor around the longitudinal axis of the transverse bore and thus the direction of transmission of the piston movement sensor signal, This requires increased effort for the embodiments known from the prior art, on the one hand in terms of manufacturing tolerances and, on the other hand, in the assembly of the piston movement sensor in the transverse bore of the cylinder head.

[0022] It is also possible that, in the case of a series of piston-cylinder units with different dimensions (in particular, different cylinder barrel diameters and thus cylinder head dimensions), piston motion sensors and, in particular, sensor housings with different dimensions must be manufactured according to the state of the art. The reason for this is that the different dimensions of the piston-cylinder units result in different distances between the sensor signal channel inside the cylinder head and the connector on the outer surface of the cylinder head, which necessitates different sensor housing lengths.

[0023] In this area of ​​tension, the invention proposes the use of a positioning and / or alignment element. The positioning and / or alignment element ensures the correct positioning of the piston movement sensor in the direction of the longitudinal axis of the transverse bore, so that the positioning ensures that the high-frequency signal of the piston movement sensor passes through the sensor signal channel, any collimator, and the pressure chamber at the correct point and / or impinges on the end face of the piston or piston rod at the correct point. Alternatively or cumulatively, the orientation of the piston movement sensor can also be specified using the positioning and / or alignment element.If the positioning and / or alignment element is used cumulatively for positioning and aligning the piston movement sensor, it can be ensured in a simple and reliable manner that a deviation in the position and alignment of a transmitted high-frequency signal of the piston movement sensor lies within a predetermined small tolerance range.

[0024] The positioning and / or alignment element is arranged in the transverse bore and is supported in the direction of the longitudinal axis of the transverse bore, namely in the assembly direction. This support can be provided, for example, on a transverse surface, inclined surface, step, taper, or an annular collar of the transverse bore. The positioning and / or alignment element thus assumes a defined axial position in the transverse bore, which can be specified during the production of the transverse bore, namely during the production of the transverse surface, inclined surface, step, taper, or annular collar.

[0025] The piston movement sensor is then supported on the positioning and / or alignment element in the direction of the longitudinal axis. Since the positioning and / or alignment element assumes a defined axial position in the transverse bore, supporting the piston movement sensor on the positioning and / or alignment element ensures that the piston movement sensor also assumes a defined position in the transverse bore.

[0026] It is advantageous that, in the event that the same piston movement sensor is used for piston-cylinder units of different dimensions, the same piston movement sensor can be used in the different piston-cylinder units, but then the predetermined position of the piston movement sensor in the transverse bore can be adjusted by the positioning and / or alignment element having different lengths.

[0027] As previously mentioned, the support of the positioning and / or alignment element can be ensured by any transverse surface, inclined surface, step, taper, or an annular collar, etc., of the transverse bore. For a particularly simple proposal of the invention, the transverse bore can be designed as a blind hole, in which case the positioning and / or alignment element is supported on a bottom (in particular the edge region of a conical bottom) of the blind hole. In this case, the depth of the blind hole can determine the position of the positioning and / or alignment element and thus also of the piston movement sensor.

[0028] It is possible for the alignment of the positioning and / or alignment element to be predetermined around the longitudinal axis of the transverse bore. This can be achieved, for example, by a positive fit between the cross sections of the housing of the positioning and / or alignment element and the transverse bore. For example, the transverse bore can have a groove or recess (or a rib or a projection) running in the direction of the longitudinal axis, which interacts in a positive fit with a rib or a projection (or a groove or recess) of the housing of the positioning and / or alignment element. However, it is also possible for the alignment of the positioning and / or alignment element to be ensured by an end face of the housing of the positioning and / or alignment element facing the bottom of the transverse bore having an eccentric recess (or projection) that engages with a corresponding projection (or recess) in the bottom.

[0029] A further aspect of the invention is dedicated to securing the positioning and / or alignment element within the transverse bore. It is proposed that at least one securing element be provided. The securing element serves to secure the longitudinal position of the positioning and / or alignment element in the transverse bore. Thus, the securing element serves to ensure that both the positioning and / or alignment element and the piston movement sensor are in their predetermined position and remain in operation. Alternatively or cumulatively, it is possible for the at least one securing element to secure the alignment of the positioning and / or alignment element around the longitudinal axis of the transverse bore (and thus possibly also secure the alignment of the piston movement sensor).

[0030] There are many different options for the design of the securing element. For example, a securing bolt, a securing cotter pin, a snap-in connection, a tongue and groove connection to ensure alignment, etc. can be used. In a very simple embodiment, the securing element is a screw. The screw can extend parallel to the longitudinal axis of the transverse bore. For example, it is possible for the screw to extend through a bore from the other side through the bottom of the blind bore. However, it is also possible for a screw forming the securing element to extend radially to a longitudinal axis of the transverse bore. In any case, the screw is accessible from the outside of the cylinder head and extends through a bore to the positioning and / or alignment element, where the screw is then screwed to an internal thread of the positioning and / or alignment element.It is further possible for the positioning and / or alignment element to have both a front-side threaded hole, which is used when the screw extends parallel to the longitudinal axis of the cross-hole, and a radially oriented threaded hole for assembly in the event that the screw extends radially to the longitudinal axis of the cross-hole.

[0031] The positioning and / or alignment element and the piston movement sensor preferably lie directly against each other via contact surfaces. These contact surfaces can ensure the correct positioning of the piston movement sensor in the direction of the longitudinal axis of the transverse bore.

[0032] It is possible that not only the axial position of the piston movement sensor in the transverse bore must be specified. Rather, it may also be necessary to specify the orientation of the piston movement sensor with regard to its angle of rotation around the longitudinal axis of the transverse bore. Specifying the angle of rotation may be necessary, for example, so that a sensor signal emitted by the piston movement sensor can pass through a sensor signal channel and / or impinge on an end face of the piston or piston rod at a defined location and / or with a defined orientation. This orientation can be specified, for example, by the piston movement sensor interacting with the transverse bore in a form-fitting manner in the circumferential direction, so that on the one hand the orientation is specified via the form fit and on the other hand this specified orientation is also maintained during operation.For example, the transverse bore can have a groove or recess running along the longitudinal axis, into which a projection or rib of the piston movement sensor housing is arranged. Conversely, it is possible for the transverse bore to have a rib or projection running along the longitudinal axis, which engages a groove or recess in the piston movement sensor housing. It is also possible for the transverse bore, on the one hand, and the piston movement sensor housing, on the other, to have corresponding non-circular, e.g., elliptical cross-sections, which ensure a precise fit in the correct orientation.

[0033] According to one embodiment of the invention, the contact surfaces of the positioning and / or alignment element, on the one hand, and the piston movement sensor, on the other hand, are connected to one another via a positive fit in the circumferential direction around the longitudinal axis of the transverse bore. This positive fit then limits or even specifies the possible relative orientations of the piston movement sensor, on the one hand, and the positioning and / or alignment element (hereinafter referred to as contact elements), on the other hand. There are many possibilities for this positive fit. To name just a few non-limiting examples, one of the two contact elements can have a projection that engages in a recess in the other contact element. It is also possible for an end face of a contact element to have a step that interacts in a positive fit with a corresponding step on the other contact element to ensure anti-twist protection and specify the alignment.

[0034] A further aspect of the invention is dedicated to enabling disassembly of the piston movement sensor, which can be carried out, for example, for maintenance purposes, in the event of a defect in the piston movement sensor, for cleaning purposes, or for the use of a different piston movement sensor with a different measuring range or a different measuring accuracy. In this case, it is advantageous if the piston movement sensor is detachably held on the positioning and / or alignment element, but the connection nevertheless ensures a certain holding force. It is advantageous if only a disassembly force that exceeds a threshold value of the holding force of the connection needs to be applied for disassembly.

[0035] In one embodiment of the invention, the piston movement sensor is connected to the positioning and / or alignment element via a locking connection. In this case, the locking force of the locking connection determines the threshold value for the holding force. If the installer applies a disassembly force to the piston movement sensor that is greater than the locking force, the locking connection can be released, and the piston movement sensor can be disassembled from the positioning and / or alignment element and removed from the transverse bore.

[0036] Another embodiment uses a permanent magnet that generates a magnetic holding force between the piston movement sensor and the positioning and / or alignment element. In this case, the threshold value for the holding force during disassembly is determined by the magnetic force. Within the scope of the invention, it is also possible for the piston movement sensor and the positioning and / or alignment element to each have a permanent magnet, between which the magnetic force is then generated.

[0037] For disassembly, the fitter can apply the required disassembly force in any way they wish. In one proposal of the invention, the piston movement sensor has a disassembly driver in the area of ​​one end face on the side facing away from the positioning and / or alignment element. The disassembly driver can be coupled to a disassembly tool. The required disassembly force can be applied to the piston movement sensor via the disassembly tool and the disassembly driver. For example, the disassembly driver can be designed as a type of hook connection into which a counter-hooking disassembly tool is hooked, the disassembly driver and the disassembly tool can form a snap-in connection, or the disassembly driver and the disassembly tool can be connected to one another via a permanent magnet. In one particular proposal of the invention, the disassembly driver is an internal thread of the piston movement sensor.A disassembly rod can then be screwed into this internal thread so that the required disassembly forces can be applied to the piston movement sensor via the disassembly rod which protrudes from the cross bore after screwing in.

[0038] The internal thread can be formed from a solid material of the sensor housing. In one proposal of the invention, the internal thread is formed by a threaded insert. This threaded insert can then be injection-molded into a sensor housing of the piston movement sensor or pressed into a bore in the sensor housing. The use of such a threaded insert is advantageous, for example, when the sensor housing is made of a material for which the production of an internal thread does not provide the necessary strength. In this case, a stronger material, in particular metal, can be selected for the material of the threaded insert. The stronger material can then provide the necessary strength for the threaded connection in the area of ​​the thread. Alternatively, the threaded insert can have an enlarged outer surface, which then enables a large-area connection and force transmission to the sensor housing.

[0039] In the embodiments known from the prior art, the piston movement sensor was hydraulically connected to the pressure chamber via the sensor signal channel, so that the piston movement sensor itself was pressurized with hydraulic fluid. This required that the sensor housing of the piston movement sensor be equipped with annular grooves on both sides of the sensor signal channel to seal the piston movement sensor in the transverse bore. If a replacement of the piston movement sensor is necessary for these embodiments, the hydraulic fluid must be drained, as otherwise the hydraulic fluid for the disassembled piston movement sensor would escape from the transverse bore. The invention proposes a design of the piston-cylinder unit in which the transverse bore is hydraulically separated from the pressure chamber via a sealing element.In this case, the piston motion sensor can be removed from the transverse bore without any risk of hydraulic fluid overflowing into the transverse bore, as the overflow is blocked by the sealing element. The sealing element is preferably designed and its material selected so that it allows the high-frequency radiation of the piston motion sensor to pass through and, if possible, does not adversely affect it.

[0040] In a particular embodiment of the invention, the sealing element is designed as a collimator, so that in this case the collimator is multifunctional, as it ensures the desired beam focusing and parallel alignment and also acts as a sealing element. It is possible for the collimator to have at least one annular groove in the area of ​​its outer surface, into which a sealing ring, in particular an O-ring, is inserted. This sealing ring interacts with the sensor signal channel in which the collimator is arranged, forming a seal.

[0041] A further solution to the problem underlying the invention is a set which has a piston-cylinder unit, as explained above. The set includes a further housing connector. These two housing connectors are designed and intended for different purposes. Thus, for example, the two different housing connectors can be housing connectors of the different types and / or subtypes explained above. The two housing connectors can then be optionally inserted into the transverse bore, and the selected housing connector can be attached to the housing of the piston-cylinder unit. The selected housing connector is then connected to the piston movement sensor via the sensor cable.In this way, a set can be provided to the customer with which the same piston movement sensor can be connected to different housing connectors in different installation situations, thus expanding the variety of applications and reducing the variety of components.

[0042] A further solution to the problem underlying the invention is a group of piston-cylinder units. Here, the group has two different subgroups of piston-cylinder units, whereby these two subgroups are then designed and intended for different purposes. In the first subgroup, the piston-cylinder units according to the invention have first housing plugs, while in the second subgroup the piston-cylinder units according to the invention have the second housing plugs. The first housing plugs and the second housing plugs are designed and intended for different purposes, whereby the piston-cylinder units of the two subgroups are then also designed and intended for different purposes. The first housing plugs and second housing plugs can differ from one another, for example, by the different types and / or subtypes explained above.Identical piston motion sensors are then present in the piston-cylinder units of the first subgroup and the piston-cylinder units of the second subgroup. For example, such a group with the different subgroups can be offered by a manufacturer or distributor, allowing the customer to purchase the piston-cylinder units of the first subgroup or the second subgroup depending on the desired application. However, it is also possible for an end customer, a repair shop, or a manufacturer of a work machine to keep such a group of piston-cylinder units in stock for different applications.

[0043] Advantageous further developments of the invention emerge from the patent claims, the description and the drawings.

[0044] The number of features mentioned in the claims and the description is to be understood as meaning that exactly this number or a greater number than the stated number is present, without the need for the explicit use of the adverb "at least." Thus, for example, if reference is made to one element, this is to be understood as meaning that exactly one element, two elements, or more elements are present. The features mentioned in the claims may be supplemented by further features or may be the only features present in the subject matter of the respective claim.

[0045] The reference signs contained in the patent claims do not represent a limitation of the scope of the subject-matter protected by the patent claims. They serve only the purpose of making the patent claims easier to understand. BRIEF DESCRIPTION OF THE CHARACTERS

[0046] In the following, the invention is further explained and described with reference to preferred embodiments shown in the figures. Fig. 1 shows a longitudinal section of a piston-cylinder unit according to the state of the art. Fig. 2 shows a partial longitudinal section of a piston-cylinder unit in the area of ​​the cylinder head. Fig. 3 shows in a spatial exploded view the cylinder head according to Fig. 2 with associated components. Fig. 4 shows a three-dimensional view of a piston movement sensor and a positioning and / or alignment element. Fig. 5 shows a three-dimensional view of a housing connector of the type DIN connector (5-pin) with sensor cable. Fig. 6 shows the housing connector with sensor cable according to Fig. 5 in a side view. Fig. 7 shows a three-dimensional view of a housing connector of the type Deutsch connector (4-pin) with sensor cable. Fig. 8 shows the housing connector according to Fig. 7in a side view. FIGURE DESCRIPTION

[0047] Unless otherwise stated below, the prior art and the embodiment according to Fig. 1 The above applies accordingly, whereby the further disclosure in the documents DE 10 2019 122 121 A1 and EP 3 957 868 A1 can also be used within the scope of the invention.

[0048] Fig. 2shows a piston-cylinder unit 1 in the region of the cylinder head 4. A sensor signal channel 26 opens into the pressure 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 movement sensor 28, which is oriented transversely to the longitudinal center axis 30. With respect to the longitudinal center axis 30, the collimator 35 is rotationally symmetrical on the other side, wherein the collimator 35 can, for example, have a curved and in particular parabolic longitudinal section, as shown. The collimator 35 has an annular groove 36 in which a sealing element 37, here an O-ring 38, is arranged. The sealing element 37 ensures a hydraulic seal between the inner wall of the sensor signal channel 26 and the collimator 35. The sensor signal channel 26 has a circumferential shoulder 39.If the pressure chamber 33 is pressurized with hydraulic pressure, the hydraulic pressure acting on the spherical end face facing the piston 7 results in a hydraulic force that presses the collimator 35 against the shoulder 39. This pressing of the collimator 35 against the shoulder 39 and / or the effect of the sealing element 37 ensures that the transverse bore 27 is not pressurized with hydraulic fluid, thus eliminating the need for additional sealing measures in the transverse bore 27. On the other hand, this seal allows the piston movement sensor 28 to be disassembled without hydraulic fluid escaping from the transverse bore 27.

[0049] As can be seen from the exploded view in Fig. 3As can be seen, a securing element 40 in the form of a screw 41, a positioning and / or alignment element 42, the piston movement sensor 28, a sensor cable 43 and a housing plug 44 are mounted in the transverse bore, wherein the housing plug 44 is fastened to a housing 46 of the cylinder head 4 via fastening screws 45.

[0050] According to Fig. 4 The positioning and / or alignment element 42 is cylindrically designed with a diameter such that the positioning and / or alignment element 42 can be inserted precisely into the transverse bore 27. The underside of the positioning and / or alignment element 42 is flat for the illustrated embodiment. The underside of the positioning and / or alignment element 42 rests against a bottom 47 of the transverse bore 27, which is designed here as a blind hole.

[0051] On the side facing the piston movement sensor 28, the positioning and / or alignment element 42 is essentially flat, but is formed with a step 48. On this side, the positioning and / or alignment element 42 has a (here cylindrical) receptacle 49 in which a permanent magnet 50 is received, which can be glued to the receptacle 49 or pressed into it. The outer surface of the permanent magnet 50 is arranged flush with a partial surface of the end face of the positioning and / or alignment element 42, away from the step 48.

[0052] On the side facing away from the piston movement sensor 28, the positioning and / or alignment element 42 has an internal thread 51 arranged eccentrically to the longitudinal axis 53 of the transverse bore 27. In the aligned position of the positioning and / or alignment element 42, installed in the transverse bore 27, the internal thread 51 of the positioning and / or alignment element 42 is aligned with an eccentric bore 52 opening into the transverse bore 27, through which the screw 41 extends from the outside through the housing 46. In this way, the positioning and / or alignment element 42 is fixed in the correct position and alignment.

[0053] It is possible that the positioning and / or alignment element 42 also has a transverse bore 54, possibly with an internal thread. If not, as in Fig. 2shown a bore 52 is present or used which is oriented parallel to the longitudinal axis 53 of the transverse bore 27, but rather a bore is provided in the housing 46 which is vertical to the plane of the drawing according to Fig. 2 oriented, as an alternative to the fastening via the screw 41, the positioning and / or alignment element 42 can be fastened via a screw which is vertical to the plane of the drawing according to Fig. 2 extends through the housing 46 and is screwed in the inner end region to the transverse bore 54 of the positioning and / or alignment element 42.

[0054] The piston movement sensor 28 has a sensor housing 55 whose outer geometry is cylindrical with a diameter such that the sensor housing 55 can be precisely seated in the transverse bore 27. Opposite this outer geometry, the sensor housing 25 has recesses in the area in which the electronics module and the transmitting and / or receiving unit for the high-frequency signal are arranged.

[0055] On the side facing the positioning and / or alignment element 42, the sensor housing 55 has a step 56, which is configured to correspond to the step 48 of the positioning and / or alignment element 42. Away from the steps 48, 56, the positioning and / or alignment element 42 and the sensor housing 55 form contact surfaces 57, 58 oriented transversely to the longitudinal axis 53, in the region of which these components abut one another in the direction of the longitudinal axis 53, thus predetermining the axial position of the piston movement sensor 28.

[0056] In contrast, the steps 48, 56 form a positive connection against rotation about the longitudinal axis 53, thus predetermining the orientation of the piston movement sensor 28. In the relative orientation specified by the steps 48, 56, a corresponding receptacle 59 with a permanent magnet 60 is provided on the sensor housing 55, aligned with the receptacle 49 and the permanent magnet 50 of the positioning and / or alignment element 42. The permanent magnet 60 is also fixed in the receptacle 59, for example, by gluing or pressing. The magnetic force between the permanent magnets 50, 60 secures the contact and thus the position and alignment between the positioning and / or alignment element 42 and the piston movement sensor 28.

[0057] On the side facing away from the positioning and / or alignment element 42, the sensor housing 55 has a flat end face 61. In the area of ​​this end face 61, the piston movement sensor 28 has an internal thread 62, which is formed here by a threaded insert 63 molded into the sensor housing 55. The internal thread 62 forms a disassembly driver 64.

[0058] Furthermore, a connector receptacle 65 is provided in the front side 61, into which a connector 66 of the sensor cable 43 can be inserted. Preferably, the format of the connector 66 and the connector receptacle 65 is a 5-pin Pico-Clasp connection (registered trademark).

[0059] Figs. 5 and 6 show a housing connector 44-I, where "I" indicates that it is a housing connector of a first type (see the explanations for the first type above).

[0060] As in Fig. 6As can be seen, the housing connector 44-I is L-shaped with a leg 67 and a leg 68 that is angled at an angle of 90°. A connector receptacle is provided in the front side of the leg 68, into which a connector 69 of the sensor cable 43 can be plugged. Preferably, both the connector receptacle and the connector 69 have the "Pico-Clasp" format.

[0061] The outer end portion of leg 68 extends into the transverse bore 27 when oriented coaxially to the longitudinal axis 53. The end portion of leg 68 may have a circumferential bead 70 or a sealing element. When inserted into the transverse bore 27, the bead 70 creates a frictionally engaged, elastically prestressed securing of leg 68 in the transverse bore 27. A seal may also be provided here.

[0062] In the exit area of ​​the leg 68 from the housing 46 of the cylinder head 4, the leg 68 has a circumferential flange 71. The flange 71 is received in a corresponding receptacle or recess in the housing 46. The flange 71 has through holes oriented parallel to the longitudinal axis 53, via which the flange 71 can be screwed to corresponding threaded holes in the housing 46. Preferably, several holes are provided in the flange 71 and threaded holes in the housing 46, so that the housing plug 44-I can be screwed to the housing 46 in different orientations around the longitudinal axis 53.

[0063] The end portion of the leg 67 forms the connector plug 34, which enables the connection of the connecting cable.

[0064] For the housing connector 44-I, the connector plug 34 has, as shown in particular in Fig. 5As can be seen, it has 5 pins 72. This is, in particular, a connector 34 of the type "DIN connector M 12 5-pin." The housing connector 44-I of the first type can be designed according to the subtypes explained above.

[0065] Figs. 7 and 8 show a housing connector 44-II, where "II" indicates that it is a housing connector of a second type. The housing connector 44-II of the second type can be designed according to the subtypes explained above.

[0066] The electronic components are integrated into the housing connector 44 in order to modify the transmitted signals from the connector 69 to the connection connector 34.

[0067] The piston motion sensor 28 directly measures the stroke of the piston 7 or the piston rod 8 within the piston-cylinder unit 1. The piston motion sensor 28 is preferably based on a non-contact radar system in which the propagation time between a transmitting unit, the end face of the piston 7 or the piston rod 8, and the reflected signal back to a receiving unit is evaluated. The propagation time can then be used to determine the position and / or speed with high accuracy and robustness.

[0068] Preferably, the piston-cylinder unit 1 with the integrated piston movement sensor 28 is designed according to protection class IP69K.

[0069] It is possible for the piston movement sensor 28 to determine a stroke 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. A resolution in the range of 0.2 mm to 4 mm, for example, 0.5 to 2 mm or 0.8 to 1.5 mm, can be achieved.

[0070] Another advantage of sealing the sensor signal channel 26 by a sealing element or a multifunctional collimator 35 is that the high hydraulic pressures, which can range from 100 bar to 600 bar, cannot lead to deformations, stresses and damages to the piston movement sensor 28, the sensor housing 55 and the electronic components of the piston movement sensor 28.

[0071] The Pico-Clasp connector used for the sensor cable 43 and its connection to the piston movement sensor 28 and the housing connector 44 can have five pins, which can be assigned to GND, VDC, CAN LO, CAN HI and an analog signal.

[0072] The analog signal can be used to transmit a pulse-width modulated (PWM) signal, with the measurement signal being transmitted via pulse-width modulation. Alternatively, a voltage or current proportional to the measurement signal can be transmitted as an analog signal.

[0073] The piston motion sensor 28 may not only measure the stroke and / or speed of the piston 7 or the piston rod 8. Alternatively, other measured variables (such as temperature) may also be measured, transmitted, and / or evaluated. The temperature can be used for temperature compensation.

[0074] It is also possible for bidirectional transmission to be possible via the housing connector 44, which also allows a software update of the piston movement sensor 28 and update functions to be carried out.

[0075] If a PWM signal is transmitted, it preferably has a frequency of 500 Hz. The duty cycle provides information about the measured piston travel. For example, if the piston is fully retracted, the duty cycle can be 5%, while for the fully extended piston, the duty cycle can be 95%. LIST OF REFERENCE SYMBOLS

[0076] 1 Piston-cylinder unit 2 Cylinder 3 Interior 4 Cylinder head 5 Bearing bush 6 Connection 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 Plain bearing 18 Lock nut 19 O-ring 20 Piston guide ring 21 Piston seal 22 Piston guide ring 23 Weld seam 24 Connection 25 Dividing chamber 26 Sensor signal channel 27 Cross bore 28 Piston movement sensor 29 Hydraulic fluid 30 Longitudinal center axis of the cylinder 31 Cylinder tube 32 Pressure chamber 33 Pressure chamber 34 Connector plug 35 Collimator 36 Annular groove 37 Sealing element 38O-ring 39Step 40Securing element 41Screw 42Positioning and / or alignment element 43Sensor cable 44Housing connector 45Fastening screws 46Housing 47Bottom 48Step 49Receptacle 50Permanent magnet 51Internal thread 52Bore 53Longitudinal axis 54Cross bore 55Sensor housing 56Step 57Contact surface 58Contact surface 59Receptacle 60Permanent magnet 61End face 62Internal thread 63Threaded insert 64Disassembly driver 65Connector receptacle 66ConnectorSensor cable 67Leg 68Leg 69Connector Sensor cable 70Bead 71Flange 72Pin

Claims

1. Piston-cylinder-unit (1) a) with a cylinder (2) having a cylinder head (4), b) with a piston (7) axially movable in the cylinder (2) and c) with a piston motion sensor (28), d) wherein the piston motion sensor (28) is arranged with an orientation in a transverse hole (27) of the cylinder head (4) having a longitudinal axis (53), so that the longest dimension of the piston motion sensor (28) extends in the direction of the longitudinal axis (53) of the transverse hole (27) wherein e) the piston motion sensor (28) is connected to a housing plug (44) through a sensor cable (43), f) the sensor cable (43) is detachably connected to the piston motion sensor (28) and / or the housing plug (44), and g) the housing plug (44) is L-shaped with two angled legs (67, 68), wherein ga) a leg (68) extends in the transverse hole (27) of the cylinder head (4) and gb) a leg (67) extends lying externally from the cylinder head (4).

2. Piston-cylinder unit (1) according to claim 1, characterized in that the housing plug (44) is detachably connected to the cylinder head (4).

3. Piston-cylinder unit (1) according to claim 2, characterized in that the housing plug (44) has a flange (71) which is screwed to the cylinder head (4).

4. Piston-cylinder unit (1) according to claim 3, characterized in that the flange (71) can be screwed to the cylinder head (4) in different alignments of the housing plug (44) about the longitudinal axis (53) of the transverse hole (27).

5. Piston-cylinder unit (1) according to one of the preceding claims, characterized in that optionally the housing plug (44-1, 44-II) in the conformation of a) DIN plug or b) Deutsch plug can be connected to the sensor cable.

6. Piston-cylinder unit (1) according to one of the preceding claims, characterized in that a positioning and / or alignment element (42) is supported in the transverse hole (27) in the direction of the longitudinal axis (53) of the transverse hole (27), and the piston motion sensor (28) is supported on the positioning and / or alignment element (42) in the direction of the longitudinal axis (53).

7. Piston-cylinder unit (1) according to claim 6, characterized in that the transverse hole (27) is a blind drilled hole and the positioning and / or alignment element (42) is supported on a base (47) of the blind drilled hole.

8. Piston-cylinder unit (1) according to claim 6 or 7, characterized in that a) a position of the positioning and / or alignment element (42) in the direction of the longitudinal axis (53) of the transverse hole (27) and / or b) an alignment of the positioning and / or alignment element (42) about the longitudinal axis (53) of the transverse hole (27) are / is locked by at least one locking element (40), wherein the locking element (40) is preferably a screw (41) that extends parallel to the longitudinal axis (53) of the transverse hole (27) or radially to the longitudinal axis (53) of the transverse hole (27).

9. Piston-cylinder unit (1) according to one of claims 6 to 8, characterized in that the positioning and / or alignment element (42) and the piston motion sensor (28) abut one another through contact surfaces (57, 58), which restrict or predefine an alignment of the piston motion sensor (28) relative to the positioning and / or alignment element (42) through a form fit in the circumferential direction about the longitudinal axis (53) of the transverse hole (27).

10. Piston-cylinder unit (1) according to one of claims 6 to 9, characterized in that the piston motion sensor (28) is retained on the positioning and / or alignment element (42) through a latching connection or a permanent magnet (50, 60).

11. Piston-cylinder unit (1) according to one of claims 6 to 10, characterized in that the piston motion sensor (28) has, on the side facing away from the positioning and / or alignment element (42), a disassembly attachment (64) which can be coupled to a disassembly tool in order to apply disassembly forces on the piston motion sensor (28) so as to disassemble the piston motion sensor (28) from the positioning and / or alignment element (42), the disassembly attachment (64) preferably being designed as an internal thread (62) of the piston motion sensor (28), and in particular the internal thread (62) being designed as a threaded insert (63) which is injected or pressed into a sensor housing (55) of the piston motion sensor (28).

12. Piston-cylinder unit (1) according to one of the preceding claims, characterized in that the transverse hole (27) is hydraulically separated from a pressure chamber (33) of the piston-cylinder unit (1) through a sealing element.

13. Set comprising a) a piston-cylinder unit (1) according to any one of claims 1 to 12 and b) another housing plug (44-1, 44-II), wherein the two housing plugs ba) are designed and intended for different purposes of use, bb) can optionally be inserted into the transverse hole (27) and bc) can be connected to the piston motion sensor (28) through the sensor cable (43).

14. Group of piston-cylinder units (1), wherein the group has two sub-groups of piston-cylinder units (1) that are designed and intended for different purposes of use, a) the first sub-group has piston-cylinder units (1) according to one of claims 1 to 12, which have the first housing plug (44-1), b) the second sub-group has piston-cylinder units (1) according to one of claims 1 to 12, which have the second housing plug (44-II), c) the first housing plugs (44-1) and the second housing plugs (44-II) are designed and intended for different purposes of use and d) the piston-cylinder units (1) of the first sub-group and the piston-cylinder units (1) of the second sub-group have structurally identical piston motion sensors (28).