PISTON-CYLINDER UNIT, SET COMPRISING A PISTON-CYLINDER UNIT AND A GROUP OF PISTON-CYLINDER UNITS

Abstract

The invention relates to a piston-cylinder unit. A piston motion sensor is arranged in a transverse bore of a cylinder head of the piston-cylinder unit. According to the invention, a positioning and/or alignment element is supported in the transverse bore on a floor, on which in turn the piston motion sensor is supported. The positioning and/or alignment element predetermines the axial position of the piston motion sensor in the transverse bore. In addition, the positioning and/or alignment element can predetermine the alignment of the piston motion sensor.

The piston-cylinder unit can be used, for example, for a work machine, construction machine, agricultural machine, a maritime machine, a wheeled loader, a digger, a dump truck, a crane, a forklift or a lifting platform.

Claims

1. A piston-cylinder unit a) with a cylinder having a cylinder head, b) with a piston axially movable in the cylinder and c) with a piston motion sensor, d) wherein the piston motion sensor is arranged in a transverse bore of the cylinder head, having a longitudinal axis, and e) wherein a positioning and/or alignment element is supported in the transverse bore in the direction of the longitudinal axis of the transverse bore and the piston motion sensor is supported at the positioning and/or alignment element in the direction of the longitudinal axis.

2. The piston-cylinder unit according to claim 1, wherein the transverse bore is a blind-hole bore and the positioning and/or alignment element is supported on a floor of the blind-hole bore.

3. The piston-cylinder unit according to claim 1, wherein a) a position of the positioning and/or alignment element in the direction of the longitudinal axis of the transverse bore, and/or b) an alignment of the positioning and/or alignment element around the longitudinal axis of the transverse bore, is/are secured by a securing element, wherein the securing element is preferably a screw which extends parallel to the longitudinal axis of the transverse bore or radially to the longitudinal axis of the transverse bore.

4. The piston-cylinder unit according to claim 1, wherein the positioning and/or alignment element and the piston motion sensor lie against one another via contact surfaces, which restrict or predetermine an alignment of the piston motion sensor relative to the positioning and/or alignment element via a form-fit in circumferential direction around the longitudinal axis of the transverse bore.

5. The piston-cylinder unit according to claim 1, wherein the piston motion sensor is held on the positioning and/or alignment element via a latching connection or a permanent magnet.

6. The piston-cylinder unit according to claim 1, wherein the piston motion sensor has, on the side facing away from the positioning and/or alignment element, a detachment catch which can be coupled to a detachment tool in order to apply detachment forces onto the piston motion sensor to detach the piston motion sensor from the positioning and/or alignment element, wherein the detachment catch is preferably formed as an internal thread of the piston motion sensor and in particular the internal thread is formed by a threaded insert, which is injected or pressed into a sensor housing of the piston motion sensor.

7. The piston-cylinder unit according to claim 1, wherein the piston motion sensor is connected to a housing plug via a sensor cable, wherein the sensor cable is preferably releasably connected to the piston motion sensor and/or the housing plug.

8. The piston-cylinder unit according to claim 7, wherein the housing plug is releasably connected to the cylinder head.

9. The piston-cylinder unit according to claim 8, wherein the housing plug has a flange, which is screwed to the cylinder head.

10. The piston-cylinder unit according to claim 9, wherein the flange can be screwed to the cylinder head in different alignments of the housing plug about the longitudinal axis of the transverse bore.

11. The piston-cylinder unit according to claim 7, wherein the housing plug is formed as an L-shape with two angled limbs, and wherein a) one limb extends into the transverse bore of the cylinder head, and b) one limb extends outside of the cylinder head.

12. The piston-cylinder unit according to claim 1, wherein the housing plug a) is formed as a DIN plug b) or as a German plug.

13. The piston-cylinder unit according to claim 1, wherein the transverse bore is hydraulically separated from a pressure chamber via a sealing element.

14. A set comprising: a) the piston-cylinder unit according to claim 1; and b) two housing plugs, which ba) are designed and intended for different applications, bb) are selectively insertable into the transverse bore, and bc) are connectable to the piston motion sensor via a sensor cable.

15. A group of piston-cylinder units comprising: a) a plurality of subgroups, each subgroup of the plurality of subgroups including the piston-cylinder unit of claim 1, wherein each subgroup of the plurality of subgroups is designed and intended for a different application, a) the piston-cylinder unit of a first subgroup of the plurality of subgroups has a first housing plug, b) the piston-cylinder unit of a second subgroup of the plurality of subgroups has a second housing plug, c) the first housing plug and the second housing plug are designed and intended for different applications, and d) the piston-cylinder unit of the first subgroup and the piston-cylinder unit of the second subgroup have identically constructed piston motion sensors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The invention will be explained further and described below with the aid of the preferred exemplary embodiments depicted in the figures.

[0062] FIG. 1 shows, in a longitudinal section, a piston-cylinder unit according to the prior art.

[0063] FIG. 2 shows, in a partial longitudinal section, a piston-cylinder unit in the region of the cylinder head.

[0064] FIG. 3 shows, in a spatial exploded view, the cylinder head according to FIG. 2 with allotted structural elements.

[0065] FIG. 4 shows, in a spatial view, a piston motion sensor and a positioning and/or alignment element.

[0066] FIG. 5 shows, in a spatial view, a housing plug of the DIN-plug (5 pin) type with a sensor cable.

[0067] FIG. 6 shows the housing plug with a sensor cable according to FIG. 5 in a side view.

[0068] FIG. 7 shows, in a spatial view, a housing plug of the German plug (4 pin) type with a sensor cable.

[0069] FIG. 8 shows the housing plug according to FIG. 7 in a side view.

DESCRIPTION OF THE DRAWINGS

[0070] Unless something different emerges from the text below, the statements made above regarding the prior art and regarding the embodiment according to FIG. 1 can apply accordingly to the embodiments according to the invention, with the further disclosure in documents DE 10 2019 122 121 A1 and EP 3 957 868 A1 also being able to be employed within the framework of the invention.

[0071] FIG. 2 shows 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 possesses, on the side facing the piston motion sensor 28, a flat end face which is aligned transversely to the longitudinal central axis 30. With regard to the longitudinal central axis 30, the collimator 35 is formed in a rotationally symmetrical manner 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 possesses a ring groove 36 in which a sealing element 37, in this case 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 possesses a shoulder 39, which is circumferential here. If the pressure chamber 33 is pressurized with hydraulic pressure, the hydraulic pressure acting on the spherical end face facing the piston 7 leads to a hydraulic force which presses the collimator 35 against the shoulder 39. This pressing of the collimator 35 on the shoulder 39 and/or the effect of the sealing element 37 can ensure that the transverse bore 27 is not pressurised by hydraulic fluid and therefore no additional sealing measures need to be taken in the transverse bore 27. On the other hand, this seal makes it possible to detach the piston motion sensor 28 without hydraulic fluid being able to escape from the transverse bore 27.

[0072] As can be seen from the exploded depiction in FIG. 3, a securing element 40 in the form of a screw 41, a positioning and/or alignment element 42, the piston motion sensor 28, a sensor cable 43 and a housing plug 44 are mounted in the transverse bore, with the housing plug 44 being affixed to a housing 46 of the cylinder head 4 via affixing screws 45.

[0073] According to FIG. 4, the positioning and/or alignment element 42 is formed to be cylindrical with a diameter such that the positioning and/or alignment element 42 can be inserted into the transverse bore 27 with a precise fit. The underside of the positioning and/or alignment element 42 is formed to be flat for the depicted exemplary embodiment. The underside of the positioning and/or alignment element 42 lies against a floor 47 of the transverse bore 27, which is formed here as a blind-hole bore.

[0074] On the side facing the piston motion sensor 28, the positioning and/or alignment element 42 is basically flat, but is formed with a step 48. On this side, the positioning and/or alignment element 42 possesses a (here cylindrical) receptacle 49 in which a permanent magnet 50 is accommodated, which can be glued onto, or pressed into, the receptacle 49. The outer surface of the permanent magnet 50 is arranged flush with a partial surface of the end side of the positioning and/or alignment element 42 away from the step 48.

[0075] On the side facing away from the piston motion sensor 28, the positioning and/or alignment element 42 possesses 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 which opens into the transverse bore 27 and through which the screw 41 extends through the housing 46 from the outside. In this manner, the positioning and/or alignment element 42 is fixed in the correct position and alignment.

[0076] It is possible that the positioning and/or alignment element 42 also has a transverse bore 54, possibly with an internal thread. If a bore 52, which is oriented parallel to the longitudinal axis 53 of the transverse bore 27, is not present or used as depicted in FIG. 2, but rather if a bore, which is oriented vertically to the drawing plane according to FIG. 2, is provided in the housing 46, it is possible, as an alternative to the affixing via the screw 41, that fixing of the positioning and/or alignment element 42 takes place via a screw which extends vertically to the drawing plane according to FIG. 2 through the housing 46 and which is screwed in the inner end region with the transverse bore 54 of the positioning and/or alignment element 42.

[0077] The piston motion sensor 28 has a sensor housing 55, the external geometry of which is cylindrical with a diameter such that the sensor housing 55 can be accommodated in the transverse bore 27 with a precise fit. Compared to this external geometry, the sensor housing 55 has recesses in the region of which the electronics unit and the transmitting and/or receiving unit for the high-frequency signal are arranged.

[0078] On the side facing the positioning and/or alignment element 42, the sensor housing 55 has a step 56, which is formed corresponding 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 which are orientated transverse to the longitudinal axis 53 and in the region of which these structural elements lie against one another in the direction of the longitudinal axis 53, whereby the axial position of the piston motion sensor 28 is predetermined.

[0079] In contrast, the steps 48, 56 form a form-fit with respect to a rotation about the longitudinal axis 53, whereby the alignment of the piston motion sensor 28 is predetermined. In the relative alignment predetermined by the steps 48, 56, a corresponding receptacle 59 with a permanent magnet 60 is provided on the sensor housing 55 in alignment 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 being pressed in. 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 motion sensor 28.

[0080] 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 region of this end face 61, the piston motion sensor 28 possesses an internal thread 62 which is formed here by a threaded insert 63 injection-molded into the sensor housing 55. The internal thread 62 forms a detachment catch 64.

[0081] Furthermore, there is provided in the end side 61 a plug receptacle 65 into which a plug 66 of the sensor cable 43 can be plugged. The format of the plug 66 and the plug receptacle 65 is preferably a 5-pin Pico-Clasp connection (registered trademark).

[0082] FIGS. 5 and 6 show a housing plug 44-1, with I indicating here that it is a housing plug of a first type (see the explanations regarding the first type above).

[0083] As can be seen in FIG. 6, the housing plug 44-1 is formed as an L-shape with a limb 67 and a limb 68 angled at an angle of 90 here. In the end side of the limb 68, there is provided a plug receptacle, into which a plug 69 of the sensor cable 43 can be plugged. Preferable, both the plug receptacle and the plug 69 have the Pico-Clasp format.

[0084] The outer end region of the limb 68 extends into the transverse bore 27 when oriented coaxially to the longitudinal axis 53. The end region of the limb 68 can possess a circumferential bead 70 or a sealing element. In the state inserted into the transverse bore 27, the bead 70 produces a frictionally engaged, elastically prestressed securing of the limb 68 in the transverse bore 27. In addition, a seal can be provided here.

[0085] In the exit region of the limb 68 from the housing 46 of the cylinder head 4, the limb 68 has a flange 71 which is circumferential here. The flange 71 is accommodated in a corresponding receptacle or depression in the housing 46. The flange 71 possesses through-bores which are oriented parallel to the longitudinal axis 53 and via which the flange 71 can be screwed together with corresponding threaded bores in the housing 46. Preferably, several bores are provided in the flange 71 as well as threaded bores in the housing 46, so that the housing plug 44-I can be screwed to the housing 46 in different alignments about the longitudinal axis 53.

[0086] The end region of the limb 67 forms the connector plug 34 which enables the connection of the connector cable.

[0087] For the housing plug 44-1, the connector plug 34 possesses 5 pins 72, as can be seen in particular in FIG. 5. In particular, this is a connector plug 34 of the DIN connector plug M 12 5 pin type. Here, the housing plug 44-I of the first type can be formed according to the sub-types explained above.

[0088] FIGS. 7 and 8 show a housing plug 44-II, with II indicating here that it is a housing plug of a second type. Here, the housing plug 44-II of the second type can be formed according to the sub-types explained above.

[0089] The electronic structural elements are integrated in each case into the housing plug 44 in order to modify the transmitted signals from the plug 69 to the connector plug 34.

[0090] By means of the piston motion sensors 28, a direct measurement of the stroke of the piston 7 or of the piston rod 8 within the piston-cylinder unit 1 is performed. The piston motion sensor 28 is preferably based on a contactlessly measuring radar system, in which the running time between a transmitting unit, the end face of the piston 7 or of the piston rod 8 and of the reflected signal back to a receiving unit is analysed. The position and/or speed can then be detected with high accuracy and robustness from the running time.

[0091] The piston-cylinder unit 1 is preferably formed with the integrated piston motion sensor 28 in accordance with the IP69K protection class.

[0092] It is possible that 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, can be detected by means of the piston motion sensor 28. 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 achieved here.

[0093] Furthermore, an advantage of the sealing of the sensor signal channel 26 by a sealing element or a multifunctional collimator 35 is that the high hydraulic pressures, which can also be 100 bar to 600 bar, cannot lead to deformations, stresses and damage to the piston motion sensor 28, the sensor housing 55 and the electronic structural elements of the piston motion sensor 28.

[0094] The Pico Clasp plug employed for the sensor cable 43 and its connection to the piston motion sensor 28 and the housing plug 44 can possess five pins, which can be assigned to GND, VDC, CAN LO, CAN HI and an analogue signal.

[0095] The analogue signal can be used to transmit a pulse-width modulated signal (PWM), with the measurement signal being transmitted via the pulse-width modulation. Alternatively, a voltage or current that is proportional to the measurement signal can be transmitted as an analogue signal.

[0096] In some circumstances, the piston motion sensor 28 measures not only the stroke and/or the speed of the piston 7 or of the piston rod 8. Alternatively, other measured variables (such as temperature) can also be measured, transmitted and/or analysed. The temperature can be used for temperature compensation.

[0097] It is also possible that bidirectional transmission is possible via the housing plug 44, with which an update of the software of the piston motion sensor 28 can take place and update functions can be performed.

[0098] If a PWM signal is transmitted, it preferably has a frequency of 500 Hz. The duty cycle provides information about the measured path of the piston. If the piston is fully retracted, then, for example, the duty cycle can be 5%, while the duty cycle can be 95% for the piston in the fully extended state.

LIST OF REFERENCE NUMBERS

[0099] 1 piston-cylinder unit [0100] 2 cylinder [0101] 3 interior space [0102] 4 cylinder head [0103] 5 bearing bush [0104] 6 connector [0105] 7 piston [0106] 8 piston rod [0107] 9 piston rod eye [0108] 10 bearing bush [0109] 11 guide bush [0110] 12 rod seal [0111] 13 O-ring [0112] 14 support ring [0113] 15 O-ring [0114] 16 wiper [0115] 17 sliding bearing [0116] 18 securing nut [0117] 19 O-ring [0118] 20 piston-guiding ring [0119] 21 piston seal [0120] 22 piston-guiding ring [0121] 23 welding seam [0122] 24 connector [0123] 25 sub-chamber [0124] 26 sensor signal channel [0125] 27 transverse bore [0126] 28 piston motion sensor [0127] 29 hydraulic fluid [0128] 30 longitudinal central axis of the cylinder [0129] 31 cylinder tube [0130] 32 pressure chamber [0131] 33 pressure chamber [0132] 34 connector plug [0133] 35 Collimator [0134] 36 ring groove [0135] 37 sealing element [0136] 38 O-ring [0137] 39 shoulder [0138] 40 securing element [0139] 41 screw [0140] 42 positioning and/or alignment element [0141] 43 sensor cable [0142] 44 housing plug [0143] 45 affixing screws [0144] 46 housing [0145] 47 floor [0146] 48 step [0147] 49 receptacle [0148] 50 permanent magnet [0149] 51 internal thread [0150] 52 bore [0151] 53 longitudinal axis [0152] 54 transverse bore [0153] 55 sensor housing [0154] 56 step [0155] 57 contact surface [0156] 58 contact surface [0157] 59 receptacle [0158] 60 permanent magnet [0159] 61 end face [0160] 62 internal thread [0161] 63 threaded insert [0162] 64 detachment catch [0163] 65 plug receptacle [0164] 66 sensor cable plug [0165] 67 limb [0166] 68 limb [0167] 69 sensor cable plug [0168] 70 bead [0169] 71 flange [0170] 72 pin