• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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  • 优先权
    • 专利摘要:
    Hydraulic cylinder with a ventilated protection device on a piston rod A hydraulic cylinder (10) has a cylinder housing (12) in which a piston (14) which varies in the cylinder housing ( 12) a pressurized space (18) and is connected on its unturned side to the pressurized space to a piston rod (20) whose end (22) not facing the pressurized space overflows out of an open end (24) of the jack housing is housed longitudinally. Between the end of the piston rod not facing the pressure space and the open end of the cylinder housing is provided a protective device (26) which has a bellows (28) surrounding the piston rod and elastically deformable according to the displacement of the piston rod, which bellows defines around the piston rod an air chamber (30) connected to the environment (34) by a connecting section (32). The connecting section is formed by at least one field (36) of openings (38) of small cross-section in the protective device (26) or in the piston rod, which provide a pressure equalization between the air chamber and the environment without producing detectable noise in the cabin. Figure for abstract: Figure 1
    公开号:FR3076872A1
    申请号:FR1873194
    申请日:2018-12-18
    公开日:2019-07-19
    发明作者:Christian Sperber；Jürgen Ryba
    申请人:FTE Automotive GmbH；
    IPC主号:
    专利说明:

    Description
    Title of the invention: Hydraulic cylinder provided with a ventilated protection device on a piston rod The present invention relates to a hydraulic cylinder. In particular, the invention relates to a hydraulic actuator or slave cylinder for hydraulic clutch actuation for motor vehicles, as used on a large scale in the automotive sector.
    A conventional hydraulic actuation of a clutch for motor vehicles has an actuator jack connected to a balancing container filled with a hydraulic liquid. The actuator cylinder has a cylinder housing in the housing bore of which a piston is housed with longitudinal sliding. The piston of the actuator cylinder defines a pressure chamber in the housing bore of the cylinder housing and can be mechanically stressed by an actuating force by means of a clutch pedal or a drive by electric motor. which is mainly carried out by means of a piston rod, as for example illustrated in the document DE 10 2016 006 053 A1 (see FIG. 2 of this document). The pressure chamber of the actuating cylinder is hydraulically connected via a pressure line to a pressure chamber of the slave cylinder, so that the pressure established in the pressure chamber by depressing the clutch pedal of the actuator cylinder or displacement of the piston of the actuator cylinder via an electric motor can be transferred to the pressure chamber of the slave cylinder via the column of liquid present in the pressurized conduit. The slave cylinder also has a cylinder housing with a housing bore in which is housed in longitudinal sliding a piston which delimits the pressure chamber of the slave cylinder and on which the pressure produced in the actuator cylinder can be applied. A piston rod, for example that presented in document DE 10 2015 010 054 A1 (see FIG. 1 of this document), is associated with the piston of the slave cylinder. This piston rod engages a clutch lever which for its part is in functional connection with the recoil bearing of the clutch. The result is that an actuating force can be applied via the piston of the slave cylinder on the recoil bearing of the clutch, to separate the thrust plate of the clutch from the drive disc of the 'clutch via a recoil mechanism and thus separate the engine from the transmission of the motor vehicle.
    The hydraulic cylinders used here (actuator cylinder or slave cylinder) are exposed to very different external influences during their operation, for example under the dashboard or in the engine space of a motor vehicle, and among these influences moisture can be counted as water and / or oil as well as dirt particles, such as dust or sand. If the displacement and sealing surfaces of the hydraulic cylinders were exposed without sufficient protection to these environmental effects, this would quickly result in significant wear on these surfaces which could lead to premature failure of the hydraulic cylinders. It is therefore necessary to provide a protection which prevents the penetration of moisture and dirt particles in the hydraulic cylinders.
    In this context, document EP 1 512 882 A2 (FIG. 1) discloses a hydraulic slave cylinder which has a cylinder housing in which a piston is housed with longitudinal sliding, which defines a space under pressure in the cylinder housing variable. On its side not turned towards the pressure space, the piston is connected to a piston rod whose end not turned towards the pressure space projects beyond an open end of the cylinder housing. Between the end of the piston rod not facing the pressurized space and the open end of the cylinder housing is provided a protective device which protects the interior of the slave cylinder from humidity and dirt particles from the environment.
    The previously known protection device also has a pleated bellows surrounding the piston rod and which can deform elastically as a function of the displacement of the piston rod, which is placed at one end on the fixed cylinder housing and by a other end on the piston rod and delimits an air chamber around the piston rod. Thanks to its elastic pleating, the pleated bellows can be crushed or extended in the manner of an accordion during a relative displacement of the piston and therefore of the piston rod relative to the cylinder housing, the piston driving back into the pleated bellows the air coming from the cylinder housing or vice versa sucking in the cylinder housing the air coming from the pleated bellows, according to the direction of movement.
    As it is often not possible to structurally obtain an identical configuration of the sliding transverse sections of the piston, that is to say of the free annular surface present between the piston rod and the cylinder housing, and the pleated bellows, i.e. the free annular surface between the piston rod and the pleated bellows, it is necessary to provide a connection of the air chamber to the environment (supply or exhaust of air) by through a connecting section to prevent the formation of an overpressure or a vacuum in the air chamber when the piston slides. Otherwise, this would cause significant deformation of the pleated bellows, i.e. crushing or swelling depending on the direction of movement of the piston, which could lead to unwanted noise, increased wear of the pleated bellows and possibly damage to the pleated bellows. by excessive wrinkling.
    In the generic state of the art described by document EP 1 512 882 A2, the connection section to the environment is formed by a simple ventilation hole whose cross-sectional area is relatively large and which is formed frontally on the end of the pleated bellows not turned towards the pressure space. The diameter of the circular ventilation hole is equal to or greater than a wall thickness of the pleated bellows at the level of its folds. During such a connection, following the displacement of the piston in the hydraulic cylinder, however, there is a pumping effect at the ventilation hole, and in operation, according to the direction of displacement of the piston, hissing noises detectable in certain circumstances inside the passenger compartment and therefore undesirable (supply and exhaust of air) occur and dirt particles as well as humidity can be sucked into the air chamber at high speed (when air supply).
    In the state of the art, there are also known pleated bellows intended to protect machine parts against dust and other foreign bodies (see for example the documents DE 2 034 753 A, DE 10 2005 028 754 Al,
    DE 10 2014 222 945 Al), in which a separate filter optionally provided with a prechamber, lips acting as valves, spacers guaranteeing a minimum cross section of the opening or the like are provided at the ventilation hole or the ventilation opening. The additional implementation associated with these provisions following the increase in the number of parts and / or a complicated configuration or manufacture of the pleated bellows at the level of the ventilation opening (s) is therefore undesirable in mass production.
    Taking into account the state of the art which has just been described, the problem to be solved by the invention consists in creating a hydraulic cylinder of configuration as simple as possible, provided with a protection device produced economically. against humidity and dirt particles from the environment, which avoids the disadvantages mentioned above and which in particular ensures an unproblematic supply and evacuation of air from the air chamber provided on the piston rod .
    This problem is solved with a hydraulic cylinder according to the present invention. Advantageous embodiments of the invention are the subject of the dependent claims.
    In a hydraulic cylinder which has a cylinder housing in which a piston which variably in the cylinder housing a space under pressure and is connected on its side not turned towards the space under pressure to a piston rod of which the end not turned towards the pressurized space projects beyond an open end of the cylinder housing is housed with longitudinal sliding, a protection device which has a bellows surrounding the piston rod and elastically deformable according to the displacement of the piston rod, which bellows defines around the piston rod an air chamber which is connected to the environment by a connecting section, being provided between the end of the piston rod not turned towards the pressurized space and the open end of the cylinder housing; the connecting section is formed according to the invention by at least one field of openings of small cross section in the protection device or in the piston rod.
    The research carried out by the inventors on the noise problem described above has led to the surprising result that if we replace the single relatively large aeration hole previously known from the connecting section between the air chamber and the environment by a field of smaller cross-sectional openings, this arrangement of openings ensures both sufficient supply and evacuation of air from the air chamber, so that the bellows of the protection device does not is not excessively deformed when the hydraulic cylinder is in operation, i.e. inflated or crushed, and at the same time effectively prevents unwanted noise from occurring when air passes through the connecting section .
    In addition, the field of openings of small cross section advantageously acts as a filter. On the one hand, from a certain size of the openings of small cross section, the fouling particles can no longer pass from the environment to the air chamber and foul the interior of the hydraulic cylinder, and on the other However, due to the size of the openings and the surface tension of the water, less moisture can statically enter the hydraulic cylinder. As several openings of small cross section are provided, it is unlikely that the connection section between the inner tube and the environment is completely clogged, i.e. is completely occupied by fouling, deposits or the like . In addition, the field of openings of small cross-section advantageously has a self-cleaning effect thanks to the fact that when an overpressure is present in the air chamber, fouling particles possibly attached to the outside on the openings of small cross section are expelled or projected outside.
    The gathering of several openings of small cross section in one field also has the advantage of being able to quickly manufacture such a connecting section, because the protection device or the piston rod must not be moved or turned on a large relative path or a large relative angle during the formation of the different openings of small cross section. Finally, the provision for supplying and removing air in and out of the air chamber is minimally invasive, in other words, do not fundamentally modify the protective devices or the piston rods. existing components, and no additional components are required.
    The elastically deformable bellows of the protection device can also be a pleated bellows as in the prior art, but this is not absolutely unavoidable. The bellows can just as easily be a drop-down or similar bellows, or another elastic cuff arranged on a piston rod.
    To form the openings of small cross section, one can consider different procedures, for example stamping, spraying water, needling with heated needles, or the like. To obtain a fast and economical production as well as a high reproducibility of the geometry of the different openings of small cross section, it is therefore preferable to drill the openings of small cross section with the laser. Thus, during the tests carried out by the inventors, openings of small cross section were formed without problem in a bellows pleated in elastomer by a CO 2 laser with a power of 300 W. This also forms a certain rounding of the fields of 'small cross-sectional openings, which is considered advantageous with a view to reducing noise.
    Basically, the individual opening of small cross section can have any cross section, for example an oval or polygonal cross section. Again, in order to obtain a simple and economical manufacture, it is in particular, however, preferable for each of the openings of small cross section to have a circular cross section.
    In principle, at least one field of openings of small cross section can be arranged at any location of the protection device or of the piston rod, provided that the openings of small cross section provide sufficient connection between the inner tube and the environment. It is however preferable that at least one field of openings of small cross section is formed at one end of the protection device or of the piston rod not turned towards the pressurized space. This position is not only good and easy to reach during the manufacture of openings of small cross section, but it also ensures that the connection between the air chamber and the environment is as far as possible from the space under pressure and therefore sealing and displacement surfaces of the hydraulic cylinder. The probability that very small fouling particles which possibly penetrate through the openings of small cross section, end up on said surfaces is thus minimized.
    Furthermore, it is basically possible to provide only one field of openings of small cross section as the connecting section between the air chamber and the environment. Preferably, however, several fields of openings of small cross section will be provided, which are arranged in a uniformly distributed manner around the periphery of the protection device. This has the advantage that the bellows deforms uniformly before or during the expulsion or aspiration of air through the openings of small cross section. Crushing on one side of the bellows or the like and therefore any associated noise is thus reliably avoided.
    In particular depending on the training site whenever possible fields of openings of small cross section, for example in a flat surface or a curved surface of the protection device, in a first variant, the openings of small section transverse of a field can be arranged in the protective device one behind the other in a line which extends transversely with respect to the piston rod. In another variant, the openings of small cross section of a field can also be arranged in columns and in lines according to a grid of rectangular perforations in top view, openings close to each column and each line being spaced from each other essentially uniform. This embodiment again allows simple and economical manufacture, in particular when the perforation pattern is square when viewed from above.
    The total number of small cross-sectional openings to be provided in the protection device or the piston rod depends in the first line on the air flow which must be displaced during a stroke of the piston and on the speed of the displacement of the piston, large air flows and / or high speeds of the piston tending to require a greater number of openings of small cross section. In the tests carried out by the inventors, it has been found in most cases to provide a total number of openings of small cross section between 20 and 100. From these tests, it has also been found that the diameter of each of the small cross-sectional openings should preferably be in a range between 0.05 and 0.2 mm and more preferably be about 0.1 mm.
    In particular to obtain a simple and economical manufacture, it is also preferable that at least part of the openings of small cross section is formed in a wall of the bellows which for the rest does not require any other modification with respect to the bellows. used so far. A ratio between the diameter of each of the small cross-sectional openings in the bellows and the thickness of the wall of the bellows should preferably be in a range between 1: 4 and 1:20. Such openings can in fact also be made advantageously quickly by forming the openings of small cross section with the laser.
    Basically, the openings of small cross section can extend obliquely in the wall of the bellows according to the specific needs of the manufacturer. However, it is preferable that the openings of small cross section extend essentially perpendicular to the wall of the bellows. Thus, the air travels the shortest path from the inside to the outside and vice versa.
    Finally, although the arrangements according to the invention can in principle be used on any hydraulic cylinder, the hydraulic cylinder envisaged will preferably be an actuator cylinder or a slave cylinder for a hydraulic clutch actuation assembly.
    The invention will now be explained in more detail with the aid of preferred embodiments, with reference to the attached partially schematic drawings in which identical or corresponding parts or characteristics have been given the same numerical references, possibly supplemented. by an apostrophe (') to characterize the second embodiment. In the drawings:
    Figure 1 shows a longitudinal sectional view cut from both sides of a hydraulic cylinder according to a first embodiment of the invention, in an unassembled and unactuated state, and this in the form of a cylinder actuator for hydraulic clutch actuation, which is provided, at an open end of a cylinder housing, with a protection device which comprises a plastically deformable pleated bellows connected to the piston rod of a piston module, which pleated bellows defines around the piston rod an air chamber which is connected to the environment by a connecting section;
    2 shows a side view on a larger scale than Figure 1 of the pleated relaxed bellows of the hydraulic cylinder of Figure 1, and shows several fields of openings of small cross section which form part of the section of connection to the environment;
    3 shows a sectional view of the pleated bellows of the hydraulic cylinder of Figure 1 along the section line III-III of Figure 2, to illustrate a distribution of the fields of openings of small cross section on the periphery of the pleated bellows;
    Figure 4 shows on an even larger scale the detail IV of Figure 3 to illustrate one of the fields of openings of small cross section;
    5 shows a sectional view of the pleated bellows of the hydraulic cylinder of Figure 1 along the line of cut V-V of Figure 2;
    Figure 6 shows on an even larger scale the detail VI of Figure 5 in order to better represent one of the openings of small cross section;
    Figure 7 uses a longitudinal section of a hydraulic cylinder according to a second embodiment of the invention in an unassembled state and snapped into a predetermined position of the stroke of a piston module, and this under the form of a slave cylinder for hydraulic clutch actuation, which is provided, at an open end of a cylinder housing, with a protection device which has an elastically deformable pleated bellows connected to a piston rod of the module piston, which pleated bellows around the piston rod defines an air chamber connected to the environment by a connecting section;
    Figure 8 shows on a much larger scale than in Figure 7 detail VIII of Figure 7 which shows in section a field of openings of small cross section which forms part of the connecting section to environment;
    9 shows on a larger scale than in Figure 7 a side view of the pleated relaxed bellows of the hydraulic cylinder of Figure 7, and shows a field of openings of small cross section which is part of the section of connection to the environment;
    10 shows on a scale which corresponds to that of Figure 9 a front view of the pleated bellows of the hydraulic cylinder of Figure 7, from the left in Figure 9, to show a distribution of the opening fields of small cross section at the periphery of the pleated bellows;
    Figure 11 is a representation on an even larger scale of the detail XI of Figure 10, to illustrate one of the fields of openings of small cross section;
    Figure 12 shows a sectional view of the pleated bellows of the hydraulic cylinder of Figure 7 along the section line XII-XII of Figure 9; and Figure 13 is an enlarged representation of detail XIII of Figure 12 in which one can find other details concerning the openings of small cross section.
    In the drawings, the elastic or elastomeric components, in particular the static or dynamic seals as well as the pleated bellows, are shown at least partially in the undeformed state to simplify the representation; in reality, these deformable components rest against the adjacent surfaces of adjacent components.
    In Figure 1, by way of example of a hydraulic cylinder, an actuator cylinder for hydraulic clutch actuation for motor vehicles is generally designated by the reference numeral 10. The actuator cylinder 10 shown in the state unconnected and not actuated has a cylinder housing 12 in which is housed in longitudinal sliding a piston 14 of a piston module 16 which defines in the cylinder housing 12 a pressure space 18 variably. On its side not turned towards the pressure space 18, the piston 14 is connected to a piston rod 20 of the piston module 16, the end 22 of which not turned towards the pressure space 18 projects from an open end 24 of the cylinder housing 12.
    As will be described in more detail below, a protective device 26 which in the embodiment shown has a pleated bellows 28 surrounding the piston rod 20 and elastically deformable according to the displacement of the rod piston, is provided between the end 22, not turned towards the pressurized space 18, of the piston rod 20 and the open end 24 of the cylinder housing 12. The pleated bellows 28 delimits around the piston rod 20 an air chamber 30 which is connected to the environment 34 via a connecting section 32. As will also be explained in more detail below, it is essential that the connecting section 32 be formed by at least one, and, in the embodiments shown, several fields 36 of openings 38 of small cross section. In the embodiments shown here, these openings 38 are provided in the protection device 26, in particular in the pleated bellows 28, and may however also be provided in other possibly provided parts of the protection device or in the piston rod , provided that these parts or the piston rod are in contact with the environment 34.
    In Figure 1, the cylinder housing 12 of the actuator cylinder 10 is made of two pieces of synthetic material and generally comprises a base body 40 of hollow housing which delimits the space under pressure 18 and a lining of housing 42 which is inserted therein and by which the piston 14 is guided in longitudinal sliding in the cylinder housing 12 and is prevented from rotating. The piston 14 which can be actuated by the piston rod 20 which projects beyond the cylinder housing 12 is made of several pieces of injection-molded synthetic material, with an external portion 44 of piston essentially in the form of a bucket which delimits in the housing cylinder 12 the pressure space 18 variable, and an inner part 46 of the piston fixed in geometric correspondence in the outer part 44 of the piston as described in detail in document DE 10 2007 010 835 A1 and cooperating with the rod piston 20.
    In Figure 1, the cylinder housing 12, more particularly its base body 40 of the housing, is provided at its end located on the left in Figure 1 with a pressure connection 48 which communicates with the space under pressure 18 and by which the actuator cylinder 10 can be hydraulically connected in a manner known per se to a slave cylinder 10 'shown by way of example in FIG. 7. The base body 40 of the housing also has a discharge connection (not shown in Figure 1) which communicates with a discharge portion 50 provided in the cylinder housing 12 and by which the actuator cylinder 10 can also be hydraulically connected in a manner known per se to a discharge container (not shown ). In Figure 1, we can also see on the cylinder housing 12 a fixing flange 52 by means of which the actuator cylinder 10 can be mounted on a bulkhead of the engine compartment (not shown) of the motor vehicle. On the side located on the right in FIG. 1, the piston rod 20 articulated on the interior part 46 of the piston by means of a connection 54 with a spherical articulation finally projects by an oval opening 56 formed at the open end 24 of the housing lining 42, which opening allows a certain angular deviation of the piston rod 20 relative to the central axis of the piston 14.
    In Figure 1, we can also see inside the actuator cylinder 10 that the housing lining 42 whose static seal vis-à-vis the base body 40 of the housing is formed by means of an O-ring 58 and held in the base body 40 of the housing by a bayonet connection generally designated by the reference numeral
    60. An annular shoulder 62 on the inner periphery side forms on the end of the housing lining 42 located on the right in FIG. 1 a stop for the piston 14. At the end of the housing lining 42 situated on the left in FIG. 1, this lining is cut into 66 in the form of a ring to accommodate a secondary sealing element 64 of elastomer. Between the base body 40 of the housing and the housing lining 42 is disposed a support ring 68 which separates the secondary sealing element 64 from a primary sealing element 70 which, for its part, is placed in an annular cutout. 72 associated with the base body 40 of the housing.
    In an operating position not shown of the piston 14, in which it is located via a cylindrical displacement surface 74 at the outer periphery of the outer part 44 of the piston, the primary sealing element 70 seals the pressurized space 18 relative to the discharge portion 50 situated between the primary sealing element 70 and the secondary sealing element 64, so that pressure can be established in the pressurized space 18 following the displacement of the piston 14 to the left in FIG. 1. Front grooves 76 and axial grooves 78 provided in a distributed manner on the periphery of the support ring 68 form with axial grooves 80 and slots located outside the displacement surface 74 of the piston 14 and also distributed on the periphery a discharge device at the space-side end under pressure of the outer part 44 of the piston. When the piston 14 is in its basic position shown in FIG. 1, this evacuation device connects the pressurized space 18 to the evacuation part 50 under the sealing contour of the primary sealing element 70 to form a pressure balance between the pressurized space 18 and the evacuation part 50, to allow evacuation of the hydraulic liquid from the evacuation part 50 into the pressurized space 18 and optionally an air exhaust out of the pressurized space 18 by the evacuation part 50. Finally, the sealing contour of the secondary sealing element 64 always rests on the displacement surface 74 of the piston 14 in order to seal the discharge part 50 vis-à-vis the atmosphere or the environment 34.
    Other details of the internal structure and of the operation of the actuator cylinder 10 will be found in document DE 10 2016 006 053 A1 to which reference is made explicitly here.
    Regarding further the pleated bellows 28 of the protective device 26, preferably formed of a thermoplastic vulcanizate (TPV) based on an ethylene-propylene-diene rubber (EPDM) and polypropylene (PP) and its attachment to the actuating cylinder 10, the piston rod 20 has, at its end 22, for connection to a clutch pedal (not shown), a connecting piece 82 which is provided on the side of its periphery exterior of a peripheral radial groove 84. The pleated bellows 28 is crimped by engagement by correspondence of shapes and in a leaktight manner in the radial groove 84 by an annular closing collar 86 which projects radially inwards and is located on the right in FIG. 1.
    At its end located on the left in Figure 1, the pleated bellows 28 also has an annular closure collar 88 which projects radially inwardly and which is crimped by engagement by correspondence of shapes and sealingly in a groove radial 90 formed in axial proximity to the open opening 24, at the outer periphery of the housing lining 42 of the cylinder housing 12. In the region of the annular collar 88, the pleated bellows 28 is also axially provided on the side of its outer periphery of a peripheral radial groove 92 which serves to take up a metallic blocking element 94 which prevents the annular collar 88 of the pleated bellows 28 from coming out of the radial groove 90 of the jack housing 12.
    Between the annular collar 86 and the annular collar 88, the pleated bellows 28 finally has several interior and exterior annular folds 96 the number of which depends on the maximum stroke of the piston 14 in the cylinder housing 12 and which ensure that the bellows pleated 28 is neither extended nor crushed to excess when the actuator cylinder 10 is in operation, and which therefore does not oppose significant resistance to the displacement of the piston.
    In Figures 1 to 3 and 5, the fields 36 of openings 38 of small cross section for supplying and discharging air from the air chamber 30 are formed at one end 98 of the protection device 26 not turned towards the pressurized space 18, and more precisely, on the side facing the pressurized space 18 of the outer annular fold 96, the furthest from the pressurized space 18, from the pleated bellows 28, near the outside diameter maximum of the pleated bellows 28. In the embodiment shown, a total of ten fields 36 of openings 38 of small cross section are provided, which are distributed uniformly over the periphery of the pleated bellows 28 as shown in FIG. 3. In Figures 1, 2 and 5, it is also clearly seen that the openings of small cross section 38 of a field 36, here five elements per field 36, are arranged in the pleated bellows 28 one behind the The others are in a line which extends transversely with respect to the piston rod 20.
    Figures 4 and 6 give further details on the different openings 38 which are here all provided in a wall 100 of the pleated bellows 28. In the embodiment shown, the openings 38 are formed by laser drilling with using a CO 2 laser, for example, with a power of 300 watts. FIG. 6 shows in particular that each opening 38 first has a cross section smaller than the thickness s of the wall 100 of the pleated bellows 28. In FIG. 4, the cross section of each opening 38 is of essentially circular shape . The diameter d of each opening 38 of small cross section is thus in a range between 0.05 and 0.2 mm and is preferably about 0.1 mm. In the tests carried out by the inventors, this order of magnitude turned out to be particularly advantageous in terms of noise production and filtration effect. With respect to the wall thickness s of the wall 100 of the pleated bellows 28, it can be seen that a ratio between the diameter d of each opening 38 of the pleated bellows 28 and the thickness s of the wall 100 of the pleated bellows 28 must be in the range of 1: 4 to 1:20. FIG. 6 also shows that the openings 38 extend essentially perpendicular to the wall 100 of the pleated bellows 28.
    The skilled person can see that in operation, that is to say during the stroke of the piston 14 in the cylinder housing 12, the actuator cylinder 10 can breathe through the fields 36 d openings 38 of small cross section formed in the pleated bellows 28 of the protection device 26. If the piston rod 20 is moved to the left in FIG. 1 by means of the connecting piece 82, the volume of air initially present in the air chamber 30 cannot completely follow the piston 14, the diameter of which is smaller than that of the pleated bellows 28, in the jack housing 12, after which it is established in the air chamber 30 a overpressure which relaxes through the openings 38 of small cross section and which therefore relieves this chamber. If, on the other hand, the piston 14 moves from an actuating position (not shown) of the actuator cylinder 10 to the right of FIG. 1, the piston 14 delivers from the cylinder housing 12 less air than the chamber air 30 which increases with the displacement of the piston rod 20 can resume inside the pleated bellows 28. Consequently, a vacuum is established in the air chamber 30 which causes that air coming from the environment 34 is sucked through the openings 38 of small cross section. As the cross section of the openings 38 is small, the latter also exert a certain filtering effect: large fouling particles, for example grains of sand, cannot thus reach the air chamber 30 through the openings 38 and therefore can not either end on the displacement surface 74 of the piston 14. The tests carried out by the inventors have further shown that both during the evacuation of air (displacement of the piston to the left in the figure 1) that during the supply of air (displacement of the piston to the right in FIG. 1) out of and into the air chamber 30, no detectable noise in the passenger compartment can be produced following the flow of air through small cross-section openings 38.
    Using FIGS. 7 to 13, we will now describe the second exemplary embodiment insofar as it differs from the first exemplary embodiment described above with reference to FIGS. 1 to 6, identical parts or characteristics or corresponding having the same reference numerals, each time supplemented by an apostrophe (') for the second embodiment.
    The hydraulic cylinder shown in Figure 7 is a slave cylinder 10 'for a hydraulic clutch actuation for motor vehicles, which has a piston module 16' which includes a piston 14 'and a piston rod 20' rigidly connected to the piston 14 '. The slave cylinder 10 'further has a cylinder housing 12' in which is formed a pressurized space 18 'delimited on one side (located on the left in FIG. 7) in a variable manner by the piston 14' taken up in longitudinal sliding in the cylinder housing 12 'and on the other side (on the right in FIG. 7) fixed by a bottom 102' of the cylinder housing 12 '. The piston 14 'made of synthetic material injected on the piston rod 20' here has an outer contour 104 'which allows the piston module 16' to be tilted in the cylinder housing 12 '.
    In addition, the piston 14 'has an appendage 106' located on the side of the pressurized space, on which appendage is maintained a sealing element 110 'in centered position by means of a retaining ring 108' . The sealing element 110 ′ rests by a peripheral sealing lip 112 ′ sliding and sealingly on a displacement surface 114 ′ situated on the interior peripheral side of the jack housing 12 ′. The retaining ring 108 'is provided on its side not turned towards the sealing element 110' with an extension 113 'stiffened. This extension 113 ′ is dimensioned such that when the piston module 16 ′ swings in the cylinder housing 12 ′, it can be placed on the displacement surface 114 ′ of the cylinder housing 12 ′ to support the piston module 16 'on the cylinder housing 12' if a predetermined tilting angle of the piston module 16 'relative to the central axis of the cylinder housing 12' has been reached, thereby avoiding leaks between the element seal 110 'and the displacement surface 114'.
    On the side of the piston 14 'not turned towards the pressurized space 18' is also arranged an elastic element 116 'which rests on the one hand on a plate spring 118' located on the housing side but separated from the cylinder housing 12 'and on the other hand cooperates with the piston rod 20' to prestress the piston module 16 'in a direction which moves away from the bottom 102' of the cylinder housing 12 '. In addition, a fixing section 120 ′ is provided, which fixes, as shown in FIG. 7, the piston module 16 ′ in a predetermined position of its stroke relative to the cylinder housing 12 ′ before a first actuation of the slave cylinder. 10 '. The fixing section 120 ′ is further configured to release the piston module 16 ′ from the cylinder housing 12 ′ during the first actuation of the slave cylinder 10 ’. In other words, the piston rod 20 ′ can be temporarily moored on the cylinder housing 12 ′ of the slave cylinder 10 ’. The fixing section 120 'is formed on the plate spring 118' and cooperates with a complementary section 122 'provided on the piston rod 20' to releasably fix the piston module 16 'relative to the cylinder housing 12' .
    In Figure 7, the housing 12 'of the slave cylinder 10', also made in the embodiment shown in injection molded synthetic material, is provided in the bottom area 102 'with two connections made of a in one piece which open into the pressurized space 18 ′ at its end situated on the right in FIG. 7. These connections are on the one hand a connection 124 ′ for exhaust air in which a known exhaust air 126 ′ in itself is housed and fixed in a sealed manner. On the other hand, it is a pressurized connection 48 ′ in which a pressurized conduit (not shown) can be plugged in hydraulically sealed manner by a plug part and be fixed so as to hydraulically connect the jack. slave 10 'in a manner known per se to a clutch actuating cylinder, for example that shown in FIG. 1. To fix the slave cylinder 10' for example on a wall of the gearbox (not shown), the housing cylinder 12 'further has, near the bottom 102', a reinforced metal fixing bore 128 'passed through when the slave cylinder 10' is in the mounted state, for example by a screw (not shown) which serves as a fixing means.
    At the open end 24 'of the cylinder housing 12', located on the left in Figure 7, the latter is provided on the side of its outer periphery with a radial groove 90 'in which a pleated bellows 28' in elastomer of a protective device 26 ', which surrounds and protects the spring element 116' and the end 22 'of the piston rod 20' which projects from the slave cylinder 10 'is crimped by an annular collar located on the side inner peripheral 88 '. A locking element 94 'which is housed in an external radial groove 92', delimited laterally by two peripheral beads, of the pleated bellows 28 ', retains the annular collar 88' radially from the outside in this position.
    At its non-turned end towards the jack housing 12 ', the pleated bellows 28' is provided with another annular collar located on the inner peripheral side 86 'which is crimped in a radial groove 84' formed on a cap 130 'of dust protection of the protection device 26'. The dust protection cap 130 ′ by which the piston rod 20 ′ engages a clutch lever (not shown) to actuate it when the slave cylinder 10 ′ is mounted in the motor vehicle, is articulated in a manner known in itself on the piston rod 20 'so as to be able to pivot relative to the piston rod 20'. More specifically, the piston rod 20 'has at its end 22' not turned towards the pressurized space 18 'a head 132' of the piston rod having a spherical end 134 'which engages by correspondence of shapes in a section inner 136 'in a spherical cap of the dust protection cap 130' so that the dust protection cap 130 'can tilt slightly relative to the head 132' of the piston rod.
    Other details of the internal structure and of the operation of the slave cylinder 10 'will be found in document DE 10 2015 010 054 A1, which is explicitly referred to here.
    Figures 9 and 10 show that in the second embodiment, only two fields 36 'of openings of small cross section 38' are provided, namely on diametrically opposite sides relative to the piston rod 20 ' on the side, not facing the pressurized space 18 ', of the last outer annular fold 96' of the pleated bellows 28 'furthest from the pressurized space 18'. In FIGS. 7 and 8, the pleated bellows 28 ′ is placed by its last inner annular fold 96 ′ on the end of the dust protection cap 130 ′ situated on the right in these figures when it is in its state of maximum crushed mounting shown in Figure 7. In addition, in Figure 8, the annular collar 86 'of the pleated bellows 28' extends in the axial direction on both sides beyond the wall 100 'of the last annular fold outside 96 'of the pleated bellows 28'. Thanks to these provisions, it is prevented that the openings of small cross section 38 'of the fields 36' can be covered from the inside by the material of the pleated bellows 28 '.
    We can also see best in Figures 10 and 11 that the openings of small cross section 38 'of each field 36' are arranged in a frame of rectangular perforations in a top view having columns 138 'and lines 140 '. Openings 38 'adjacent to each column 138' and each row 140 'are spaced apart from each other in a substantially uniform manner. In the example of embodiment shown, this perforation pattern is square in a plan view, with each time five openings 38 'of small cross section per column 138' and line 140 ', and therefore with a total of twenty-five openings 38 'of small cross section in each field 36'. With regard to the shape and dimensions of the various openings 38 ′ of small cross section, reference is made here to the explanations given above with regard to the first exemplary embodiment.
    Those skilled in the art also see that in operation, that is to say when the piston 14 'moves in the cylinder housing 12', the slave cylinder 10 'can breathe through the fields 36 'of openings 38' of small cross section formed in the pleated bellows 28 'of the protection device 26'. If during a displacement of the piston, an overpressure is established in the air chamber 30 'delimited by the pleated bellows 28', this overpressure relaxes by means of the openings 38 'of small cross section and the chamber air can be released from its air. If, on the other hand, during a displacement of the piston, a vacuum is established in the air chamber 30 ′, air coming from the environment 34 ′ is sucked in through the openings of small cross section 38 ′, the fields 36 'of openings 38' of small cross-section exert a filtering effect and fouling particles from the environment 34 'are prevented from entering the interior of the slave cylinder 10'. Differences in pressure between the air chamber 30 'and the environment 34' caused by temperature differences are also compensated for by the openings of small cross section 38'38 ', which also applies to the first example of embodiment. The pleated bellows 28 ′ can therefore never inflate or crush excessively.
    Although in this embodiment, the fields 36 'of openings 38' of small cross section are also formed in the pleated bellows 28 'again preferably by laser drilling, the openings of small cross section 38' can replace or additionally be provided also in the cap 130 'of dust protection of the protection device 26'.
    Regarding the two exemplary embodiments which have just been described, it must finally be indicated that according to the tests carried out by the inventors, the total number of openings of small cross section 38, 38 ′ should preferably be understood between 20 and 100. Surprisingly, these tests also showed that the total cross-sectional area of the connection section 32, 32 'with the environment 34, 34' formed by all the small cross-sectional openings 38, 38 'of the protection device 26, 26 'concerned can be significantly smaller than the cross section of previously known solutions to a hole (for example EP 1 512 882 A2) without this compromising an adequate supply and evacuation of air from the chamber air 30, 30 'concerned. In all cases, no noise was detectable in the passenger compartment following the flow of air through the openings of small cross section 38, 38 '.
    A hydraulic cylinder has a cylinder housing in which a piston which variably delimits in the cylinder housing a pressure space and is connected on its side not turned towards the pressure space to a piston rod whose l the end not turned towards the pressurized space projects beyond an open end of the cylinder housing is housed with longitudinal sliding. Between the end of the piston rod not turned towards the pressure space and the open end of the cylinder housing is provided a protection device which has a bellows surrounding the piston rod and elastically deformable according to the displacement of the piston rod, which bellows defines around the piston rod an air chamber connected to the environment by a connecting section. The connecting section is formed by at least one field of openings of small cross section in the protection device or in the piston rod, which ensure a pressure equalization between the air chamber and the environment without producing detectable noise in the passenger compartment.
    权利要求:
    Claims (1)
    [1" id="c-fr-0001]
    [Claim 6]
    claims
    Hydraulic cylinder (10, 10 ') provided with a cylinder housing (12, 12') in which a piston (14, 14 ') which variably delimits in the cylinder housing (12, 12') a space under pressure (18, 18 '), and is connected on its side not turned towards the pressure space (18, 18') to a piston rod (20, 20 ') whose end (22, 22') does not facing the pressurized space (18, 18 ') projects beyond an open end (24, 24') of the cylinder housing (12, 12 ') is housed in longitudinal displacement, a protective device (26, 26 ') which has a bellows (28, 28') surrounding the piston rod (20, 20 ') and elastically deformable as a function of the displacement of the piston rod, which bellows delimits around the piston rod (20, 20' ) an air chamber (30, 30 ') connected to the environment (34, 34') by a connecting section (32, 32 '), being provided between the end (22, 22') of the rod piston (20, 20 ') not facing the pressure space ( 18, 18 ') and the open end (24, 24') of the cylinder housing (12, 12 '), characterized in that the connecting section (32, 32') is formed by at least one field (36 , 36 ') of openings (38, 38') of small cross section in the protection device (26, 26 ') or in the piston rod.
    Hydraulic cylinder (10, 10 ') according to claim 1, characterized in that the openings (38, 38') of small cross section are laser drilled.
    Hydraulic cylinder (10, 10 ') according to claim 1 or 2, characterized in that the openings (38, 38') of small cross section each have a circular cross section.
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that the field or fields (36, 36') of openings (38, 38 ') of small cross section are formed on one end (98 , 98 '), not facing the pressurized space (18, 18'), the protective device (26, 26 ') or the piston rod.
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that several fields (36, 36') of openings (38, 38 ') of small cross section are provided, which are arranged in a distributed manner uniformly around the periphery of the protection device (26, 26 ').
    Hydraulic cylinder (10) according to one of the preceding claims, characterized in that the openings (38) of small cross section of a [Claim 7] [Claim 8] [Claim 9] [Claim 10] [Claim 11] [ Claim 12] [Claim 13] [Claim 14] [Claim 15] Field (36) are arranged in the protective device (26) one behind the other in a line which extends transversely to the piston rod ( 20).
    Hydraulic cylinder (10 ') according to one of claims 1 to 5, characterized in that the openings (38') of small cross section of a field (36 ') are arranged in columns (138') and in lines ( 140 ′) in a rectangular perforation pattern in top view of the openings (38 ′) adjacent to each column (138 ′) and row (140 ′) being spaced apart from each other in essentially identical manner.
    Hydraulic cylinder (10 ') according to claim 7, characterized in that seen from above, the mesh of perforations is square.
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that the total number of openings (38, 38') of small cross section is between 20 and 100.
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that the diameter (d) of each of the openings (38, 38') of small cross section is in a range between 0.05 and 0.2 mm.
    Hydraulic cylinder (10, 10 ') according to claim 10, characterized in that the diameter (d) of each of the openings (38, 38') of small cross section is about 0.1 mm.
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that at least part of the openings (38, 38') of small cross section is formed in a wall (100, 100 ') of the bellows (28, 28 ').
    Hydraulic cylinder (10, 10 ') according to claim 12, characterized in that a ratio between the diameter (d) of each of the openings (38, 38') of small cross section in the bellows (28, 28 ') and the thickness (s) of the wall (100, 100 ') of the bellows (28, 28') is in a range between 1: 4 and 1:20.
    Hydraulic cylinder (10, 10 ') according to claim 12 or 13, characterized in that the openings (38, 38') of small cross section extend essentially perpendicular to the wall (100, 100 ') of the bellows (28, 28 ').
    Hydraulic cylinder (10, 10 ') according to one of the preceding claims, characterized in that the hydraulic cylinder is an actuator cylinder (10) or a slave cylinder (10') for a hydraulic clutch actuation assembly.
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    同族专利:
    公开号 | 公开日
    DE102017011793B3|2019-05-16|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3041885A|1959-05-11|1962-07-03|Baldwin Montrose Chemical Comp|Bellows|
    DE2034753C3|1970-07-14|1974-05-09|Fa. Carl Freudenberg, 6940 Weinheim|Bellows|
    DE10341470A1|2003-09-05|2005-04-07|Fte Automotive Gmbh & Co. Kg|hydraulic cylinders|
    DE102005028754B4|2004-07-15|2013-05-29|Zf Friedrichshafen Ag|Folding cover for hydraulic, hydropneumatic or pneumatic piston-cylinder units|
    FR2881501B1|2005-02-02|2008-09-12|Bosch Gmbh Robert|PROTECTIVE SLEEVE FOR SLIDING MECHANICAL SYSTEM|
    JPWO2008032462A1|2006-09-15|2010-01-21|三菱電機株式会社|Actuator|
    DE102007010835A1|2007-03-03|2008-09-04|Fte Automotive Gmbh|Hydraulic cylinder, especially master cylinder for vehicle clutch or brake, has piston with inner part snap-fitted into outer part by elastic latching region on inner part latching into reverse cut region on outer part|
    DE202011000391U1|2011-02-21|2014-03-31|Hofer Mechatronik Gmbh|clutch actuator|
    DE102014222945A1|2013-12-04|2015-06-11|Schaeffler Technologies AG & Co. KG|Bellows with ventilation|
    DE102015010054A1|2015-08-07|2017-02-09|Fte Automotive Gmbh|Hydraulic cylinder, in particular slave cylinder for a hydraulic clutch actuation for motor vehicles|
    DE102016006053A1|2016-05-18|2017-11-23|Fte Automotive Gmbh|Hydraulic cylinder, in particular master cylinder for a hydraulic clutch or brake actuation for motor vehicles|US10780756B1|2019-04-23|2020-09-22|RB Distribution, Inc.|Purging dust boot|
    DE202021102467U1|2021-05-06|2021-06-18|Fte Automotive Gmbh|Hydraulic cylinders for hydraulic clutch actuation for motor vehicles|
    法律状态:
    2019-12-31| PLFP| Fee payment|Year of fee payment: 2 |
    2020-12-31| PLFP| Fee payment|Year of fee payment: 3 |
    2021-06-25| PLSC| Publication of the preliminary search report|Effective date: 20210625 |
    2021-12-31| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
    申请号 | 申请日 | 专利标题
    DE102017011793.4|2017-12-20|
    DE102017011793.4A|DE102017011793B3|2017-12-20|2017-12-20|Hydraulic cylinder with a vented guard on a piston rod|
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