DE102018205184A1 - Sealing device and hydraulic piston with sealing device - Google Patents

Abstract

The invention relates to a sealing device (100, 100 '), a hydraulic piston (101), a length-adjustable connecting rod (103) and a manufacturing method for producing such a sealing device (100, 100'). A first annular sealing device (1) with a first gap (1 ') and a second annular sealing device (2) with a second gap (2') are seated radially in a manner on a third sealing device (3) with a third gap (3 '). ) that the first seal means (1) and the second seal means (2) are juxtaposed in an axial direction and the first gap (1 '), the second gap (2') and the third gap (3 ') in a circumferential direction each shifted from each other.

Description

The invention relates to a sealing device for sealing hydraulic chambers of a length-adjustable connecting rod, in particular an internal combustion engine, a hydraulic piston with such a sealing device, a length-adjustable connecting rod with such a hydraulic piston and a manufacturing method for producing such a sealing device.

In order to influence the power transmission from a reciprocating piston to a crankshaft in an internal combustion engine, length-adjustable connecting rods are known from the prior art. Through this it is possible to change a compression ratio of the internal combustion engine and in particular to adapt to work steps of a working cycle of the internal combustion engine and / or to driving situations of a vehicle, which is equipped with a corresponding internal combustion engine. For example, it may be desirable to operate the internal combustion engine at full load with a low compression ratio and at partial load or during startup with an increased compression ratio, such that peak pressures can be reduced under full load, fuel economy reduced at part load, or compression pressure increased at startup.

In some length-adjustable connecting rods hydraulic systems are provided for adjusting the connecting rod length, by means of which movably mounted parts of the connecting rod can be moved and / or fixed in a desired position. For this purpose, a hydraulic medium in hydraulic chambers, which are generally formed by a hydraulic piston in a hydraulic cylinder, acted upon by a predetermined pressure.

It is an object of the invention to improve a hydraulic adjustment of a length of a length-adjustable connecting rod, in particular to increase the reliability of setting.

This object is achieved by a sealing device, a hydraulic piston, a length-adjustable connecting rod and a manufacturing method for such a sealing device according to the independent claims. Advantageous embodiments are the subject of the dependent claims.

A first aspect of the invention relates to a sealing device for sealing hydraulic chambers of a length-adjustable connecting rod, in particular an internal combustion engine, wherein the sealing device comprises a first annular sealing device with a first gap, a second annular sealing device with a second gap and a third annular sealing device with a third gap , Preferably, the first and second sealing means are seated radially on the third sealing means in such a manner that the first sealing means and the second sealing means are arranged side by side in an axial direction. In this case, the first gap, the second gap and the third gap are preferably displaced relative to each other in a circumferential direction.

A second aspect of the invention relates to a hydraulic piston, in particular a replaceable piston, with at least one sealing device according to the first aspect of the invention.

A third aspect of the invention relates to a length-adjustable connecting rod for use in a variable compression ratio internal combustion engine comprising a hydraulic cylinder and a hydraulic piston according to the second aspect of the invention.

A fourth aspect of the invention relates to a manufacturing method for a sealing device according to the first aspect of the invention. In this case, the first and second sealing device is placed on the third sealing device in such a way that the first sealing device is arranged axially adjacent to the second sealing device. Preferably, both an upper side of the first sealing device together with an upper side of the third sealing device and a lower side of the second sealing device are ground flat together with a lower side of the third sealing device.

The features and advantages described below in relation to the first aspect of the invention and its advantageous embodiment apply, where technically reasonable, also for the second, third and fourth aspects of the invention and its advantageous embodiment and vice versa.

For the purposes of the invention, an annular sealing device with a slot is to be understood as meaning a sealing ring which has a slot-like gap along its circumference, ie. is interrupted at one point. In particular, an annular sealing device with a slot is topologically a cylinder or cuboid bent along a circle.

For the purposes of the invention, a hydraulic chamber is to be understood as a preferably sealed space which can be charged with a hydraulic medium, in particular an oil. In this case, a hydraulic chamber is preferably of at least two relatively movably mounted elements, such as a hydraulic cylinder, in the Hydraulic piston is introduced or is formed. The hydraulic medium is preferably acted upon by a pressure, whereby the two elements can be moved relative to each other.

For the purposes of the invention, radial or radial direction, axial or axial direction or circumferential direction are respectively directions along a radius of the circular sealing device or sealing device (s), along a perpendicular to a radius of the circular sealing device or sealing device (s) Scope of the sealing device or sealing device (s) to understand.

In the context of the invention, a retaining lug means a locking means, in particular a projection for blocking a rotary movement, with which preferably a rotation of the first, second and / or third sealing device in the circumferential direction can be prevented from one another. Preferably, a retaining lug is designed or set up to support the first, second or third sealing device against each other.

The invention is based in particular on the approach that, with a staggered arrangement of slotted, annular sealing devices in the region of a hydraulic chamber of a length-adjustable connecting rod, leakage of a hydraulic medium, in particular creeping of hydraulic medium, out of the hydraulic chamber formed by a hydraulic cylinder and a hydraulic piston of the length-adjustable connecting rod avoidable or at least reducible.

A staggered arrangement according to the invention relates on the one hand the spatial arrangement of the sealing means and on the other hand, the alignment of the slots of the sealing means in a circumferential direction of the sealing means relative to each other. In particular, the slots of the sealing devices in this arrangement are each arranged at different positions along the circumference of the sealing devices.

The staggered arrangement preferably extends along two spatial dimensions, in particular along an axial direction and a radial direction. Preferably, in each case two sealing devices are arranged axially or radially next to each other and thereby displaced or rotated in such a way along their circumferential direction that their slots are arranged spatially separated from each other in the circumferential direction.

As a result, leakage of hydraulic medium through a slot of a sealing device is prevented or at least reduced by two adjacently arranged further sealing devices. In particular, the first slot of the first sealing means is sealed in the axial direction by the second sealing means and in the radial direction by the third sealing means, i. covered. Accordingly, the second slot of the second sealing means is sealed in the axial direction by the first sealing means and in the radial direction by the third sealing means, i. covered. Also, the third gap is sealed in the radial direction by the first and second sealing means, i. covered.

Overall, the invention allows hydraulic medium in a hydraulic chamber of a length-adjustable connecting rod can be reliably acted upon by a predetermined pressure.

In an advantageous embodiment, the sealing device has a securing element, which is adapted to fix the sealing means in the circumferential direction relative to each other. This reliably prevents the first, second and third gaps of the first, second and third sealing devices from being axially or axially displaced by a rotation of the first, second and / or third sealing device. Radial direction next to each other come. Thus, hydraulic medium can not pass from the first into the second and / or third gap or vice versa and / or from the second into the third gap or vice versa and thus compromise the sealing effect of the sealing device.

In a further advantageous embodiment, the securing element has a first retaining lug arranged on the first sealing device and a second retaining lug arranged on the second sealing device. Preferably, the first and second retaining lugs are each adapted to engage in the third gap. Preferably, the first or second retaining lug is designed such that it protrudes in the radial direction from the first and second sealing device. Preferably, the first and second retaining lug projects radially inward.

The first and second retaining lugs are preferably embossed in the first and second sealing device. Preferably, the first and second retaining lugs are shaped in such a way that they form a, in particular hollow, hemisphere when engaging in the third gap.

As a result, the securing element can be made easily, in particular in one piece with or out of the first or second sealing device, and enables reliable fixing, in particular Anti-rotation, the first, second and / or third sealing device relative to each other.

In a further advantageous embodiment, the first sealing device has a first groove and the second sealing device has a second groove. Preferably, the securing element is arranged to parts in the first groove, the second groove and the third gap or a bore of the third sealing device. Thereby, the securing element can be easily integrated into the sealing device and allow a reliable fixation of the first, second and / or third sealing means relative to each other.

In a further advantageous embodiment, the securing element has a securing pin. Preferably, the locking pin is arranged and / or arranged to pass through the third gap or the bore and engage in the first and second groove. Preferably, the locking pin is also set up or designed such that it can be inserted into a locking pin bore of a hydraulic piston. In this case, the locking pin can be pressed into the bore and / or the first and second groove. As a result, the first, second and third securing devices can be secured against rotation relative to one another and / or relative to a hydraulic piston simply and reliably.

In a further advantageous embodiment, the securing element has a safety ball, which rests in the third gap and in the first and second groove. Preferably, the first and second groove are formed such that they form a hemispherical recess for receiving the safety ball when receiving the backup copy. Thereby, the sealing device with the securing element can be easily mounted.

In a further advantageous embodiment, the total axial height of the first and second sealing means in a seated state on the third sealing means corresponds at least substantially to the axial height of the third sealing means. In other words, an upper side of the first sealing device is preferably aligned with an upper side of the third sealing device in a radial plane. Correspondingly, a lower side of the second sealing device is preferably flush with a lower side of the third sealing device opposite the upper side of the third sealing device in a radial plane. As a result, the sealing device can be accurately inserted and fixed in a groove, but at least the axial play in the groove can be reduced.

Under a top or bottom of a sealing device in the context of the invention is in each case a substantially perpendicular to the axial direction surface, in particular end face to understand the sealing device. A surface normal of the upper side is aligned opposite to a surface normal of the lower side, i. The top and bottom of a sealing device are opposite. Alternatively, instead of the top and bottom, it is also possible to speak of a first or second end face.

In a further advantageous embodiment, the overall axial height of the first and second sealing means and the axial height of the third sealing means is between 0.75 mm and 5 mm, preferably between 1 mm and 2 mm, in particular between 1.25 mm and 1.75 mm. Such dimensioned sealing devices allow on the one hand a space-saving use in a length-adjustable connecting rod, but on the other hand have sufficient axial extent to achieve a reliable seal of a hydraulic chamber in this connecting rod.

In a further advantageous embodiment, an outer diameter of the first and second sealing device is in each case between 15 mm and 25 mm, preferably between 17.5 mm and 22.5 mm, in particular between 19 mm and 21 mm. Preferably, the outer diameter of the first and second sealing device corresponds in each case at least substantially to a diameter of a lateral surface of a hydraulic piston of a length-adjustable connecting rod, wherein the sealing device can be mounted on the hydraulic piston or is.

Such dimensioned sealing devices allow on the one hand a space-saving use in a length-adjustable connecting rod, but on the other hand have sufficient radial extent to allow the reliable sealing of a gap between a hydraulic piston with a large effective area and a hydraulic cylinder.

In a further advantageous embodiment, an inner diameter of the first and second sealing means on the one hand and an outer diameter of the third sealing means on the other hand each between 14 mm and 24 mm, preferably between 16 mm and 22 mm, in particular between 18 mm and 20 mm. Preferably, the inner diameters of the first and second sealing means on the one hand and the outer diameter of the third sealing means on the other hand selected such that the first and second sealing means on the third sealing means fixed, in particular rotationally fixed and sealing, preferably with a given pressure, sit or sit up.

Such dimensioned sealing means allow on the one hand a space-saving use in a length-adjustable connecting rod, but on the other hand, however, have a sufficient radial extent in order to be able to be mounted on a mechanically stable hydraulic piston with a large effective surface.

In a further advantageous embodiment, an inner diameter of the third sealing device is between 13 mm and 23 mm, preferably between 15 mm and 21 mm, in particular between 17 mm and 19 mm. In this case, the inner diameter of the third sealing device preferably defines the inner diameter of the sealing device. Preferably, the inner diameter of the third sealing means is selected such that the sealing device on a lateral surface of a hydraulic piston of a length-adjustable connecting rod fixed, in particular rotationally fixed and sealing, preferably with a predetermined pressure, seated or can sit.

Such dimensioned sealing means allow on the one hand a space-saving use in a length-adjustable connecting rod, but on the other hand, however, have a sufficient radial extent in order to be able to be mounted on a mechanically stable hydraulic piston with a large effective surface.

In a further advantageous embodiment, the first, second and third sealing means are each made of spring steel. As a result, the sealing devices or the sealing device are resistant to abrasion and allow a long-lasting, reliable sealing of a hydraulic chamber in a length-adjustable connecting rod.

In a further advantageous embodiment, the first and the second gap are displaced in the circumferential direction by substantially 180 degrees to each other. Thereby, the first gap in the axial direction can reliably be reliably sealed by the second sealing means and the second gap in the axial direction can be reliably sealed by the first sealing means, i. be covered. Preferably, the first and second sealing means, such as when they are placed on a hydraulic piston or are, in particular in a groove of the hydraulic piston are or are, pressed against each other with a predetermined pressure in the axial direction. The orientation of the first gap in a radial direction, which is substantially opposite to a radial alignment direction of the second gap, allows the first and second sealing device in this case a mechanically stable bearing surface in the region of the first and second gap.

Preferably, the third gap in the circumferential direction relative to the first and second gap in each case by substantially 90 degrees. Thereby, the first and second gaps in the radial direction are reliably sealed by the third sealing means, i. covered.

In a further advantageous embodiment, a gap width of the first, second and third gaps in the seated state of the first and second sealing means on the third sealing means is less than 75 μm, preferably less than 50 μm, in particular less than 10 μm. Preferably, the inner and outer diameters of the first, second and third sealing means are selected or coordinated such that the aforementioned gap widths can be realized or undershot. By designing the sealing devices with such small gap widths, the leakage of hydraulic medium through one of the gaps of the sealing devices from a hydraulic chamber in a length-adjustable connecting rod can be avoided or at least reduced and thus enables a particularly reliable sealing of the corresponding hydraulic chamber.

In a further advantageous embodiment, a first sealing device in a region of a first end face of the hydraulic piston and a second sealing device in a region of the first end face opposite, second end face of the hydraulic piston is arranged. This arrangement of first and second sealing device is particularly advantageous when the hydraulic piston is designed as a replaceable piston, i. with the first end face forms a first hydraulic chamber and the second end face a second hydraulic chamber or closes, so that each of the end faces acted upon by a pressure and formed as a replaceable piston hydraulic piston can thereby be moved axially. Each of the sealing device is configured to seal one of the two hydraulic chambers against leakage of hydraulic medium.

In a further advantageous embodiment, the hydraulic piston on a lateral surface, which is axially bounded by the first end face and the second end face, wherein the lateral surface in the region of the first end face a first, the lateral surface circumferential groove for receiving the first sealing device and in the region of the second End face a second, the lateral surface circumferential groove for receiving the second sealing device. In particular, the first and second end faces over the lateral surface of the preferred Cylindrically shaped hydraulic piston connected together.

Preferably, the first and second groove are formed such that the first and second sealing device can be accommodated in each case accurately. In particular, the first and second groove are formed such that a lateral surface of the first and second sealing device terminates almost flush with the lateral surface of the hydraulic cylinder and only by between 100 .mu.m and 1 .mu.m, preferably between 75 .mu.m and 10 .mu.m, in particular between 50 and 20 microns protrude from the groove.

Thereby, the first and second sealing device can be fixed and arranged on the one hand safe and space saving on the hydraulic piston even on movement of the hydraulic piston, and on the other hand a reliable seal against leakage of hydraulic fluid from each one adjacent to the first and second end faces of the hydraulic piston hydraulic chamber can be achieved.

In a further advantageous embodiment, the first groove and the second groove are each formed in such a way that the respectively arranged therein sealing devices in the radial direction have a game, which in particular allow compensation for the expansion of the sealing devices in their heating and / or cover manufacturing tolerances and so that an optimal sealing effect of the sealing devices can afford. Thus, in particular, it is possible to prevent hydraulic medium in contact with the sealing device between the first or second sealing device and a hydraulic cylinder in which the hydraulic piston with the two sealing devices is inserted between the first or second sealing device and the third sealing device or between the third sealing device and the hydraulic piston or a groove bottom creeps. At the same time, the play of the sealing devices is large enough to absorb temperature-induced changes in the diameter of the sealing devices, so that the sealing devices reliably seal the hydraulic chambers closed by the hydraulic piston even with heavy heating during operation of the hydraulic piston.

In a further advantageous embodiment, the hydraulic piston has an axially arranged blind hole, wherein the hydraulic piston can be connected by means of the blind hole with a shaft, in particular a length-adjustable connecting rod. For this purpose, the blind hole preferably has a thread, in particular an internal thread, which interacts or may interact with a thread, in particular external thread, of the shaft. Thereby, the hydraulic piston can be easily and reliably connected by screwing with the shaft, which on the one hand enables a safe transmission of the hydraulic piston movement on the shaft and on the other hand an efficient production of length-adjustable connecting rods with such hydraulic cylinders.

In a further advantageous embodiment, the hydraulic piston has at least one fastening recess, which is arranged on the lateral surface of the hydraulic piston and is adapted or adapted to interact with a tool for connecting the hydraulic piston to the shaft. The at least one fastening recess preferably surrounds the lateral surface of the hydraulic piston. In this case, the fastening recess can be arranged axially between the first sealing device and the second sealing device. Preferably, the mounting recess is formed or shaped as a hexagon screw or counterpart of an (external) hexagonal wrench, so that the hydraulic piston can be easily and reliably screwed onto the shaft by means of the hexagonal wrench.

In a further advantageous embodiment, the length-adjustable connecting rod has a shaft with which the hydraulic piston can be connected, in particular screwed, is. About the shaft is a small connecting rod of the length-adjustable connecting rod with the hydraulic piston in operative connection, so that a hydraulically caused movement of the hydraulic piston in the axial direction has such a movement of the small connecting rod result.

In a further advantageous embodiment, the connecting rod has an anti-rotation device which is adapted to fix the shaft in a circumferential direction relative to the hydraulic cylinder. As a result, a predetermined orientation of the small connecting rod end connected to the shaft can also be ensured during operation of the length-adjustable connecting rod and vibrations avoided or at least reduced by periodic movements of the shaft and / or the hydraulic piston along the circumferential direction in the hydraulic cylinder.

In a further advantageous embodiment, the anti-rotation device in the hydraulic cylinder in the axial direction movable, connected to the shaft sleeve member and a radially projecting into the hydraulic cylinder pin member, wherein the pin member engages in a arranged on a shell side of the sleeve member in the axial direction guide groove of the sleeve member. As a result, the pin member reliably rotation of the sleeve member and thus the shaft or the Prevent hydraulic piston and the small connecting rod along the circumferential direction.

• 1 ein erstes bevorzugtes Ausführungsbeispiel einer Dichtungsvorrichtung;
• 2 ein zweites bevorzugtes Ausführungsbeispiel einer Dichtungsvorrichtung;
• 3 ein drittes bevorzugtes Ausführungsbeispiel einer Dichtungsvorrichtung;
• 4 ein viertes bevorzugtes Ausführungsbeispiel einer Dichtungsvorrichtung;
• 5 ein bevorzugtes Ausführungsbeispiel einer längenverstellbaren Pleuelstange; und
• 6 ein bevorzugtes Ausführungsbeispiel eines Hydraulikzylinders.

Other features, advantages and applications of the invention will become apparent from the following description of exemplary embodiments in conjunction with the figures, in which the same reference numerals for the same or corresponding elements of the invention are used throughout. At least partially schematically show:

• 1 a first preferred embodiment of a sealing device;
• 2 a second preferred embodiment of a sealing device;
• 3 a third preferred embodiment of a sealing device;
• 4 a fourth preferred embodiment of a sealing device;
• 5 A preferred embodiment of a length-adjustable connecting rod; and
• 6 a preferred embodiment of a hydraulic cylinder.

In 1 is a first preferred embodiment of a sealing device according to the invention 100 shown, which three annular sealing devices 1-3 having.

The first sealing device 1 , which has a first gap 1 ', and the second sealing device 2, which has a second gap 2', are preferably arranged concentrically with the third sealing device 3, which has a third gap 3 '. In this case, the first sealing device 1 and the second sealing device 2 is preferably arranged axially next to one another, ie above or below one another in the illustrated illustration, and surrounds the third sealing device 3.

In other words, the first and second sealing device sit 1 , 2 preferably on the third sealing means 3, wherein an outer diameter of the third sealing means 3 is substantially an inner diameter of the first and second sealing means 1 , 2 corresponds.

This includes a top o1 the first sealing device 1 preferably aligned with a top o3 the third sealing device 3 from. Analog closes a base 2u the second sealing device 2 preferably in alignment with a bottom 3u the third sealing device 3 from.

Such a stepless top and bottom of the sealing device 100 For example, by arranging the sealing means 1-3 in the manner shown and subsequent surface grinding of the top and bottom of the sealing device 100 getting produced.

By the in 1 illustrated arrangement of first, second and third sealing means 1 , 2, 3 is the first gap 1 'of the first sealing device 1 preferably in the axial direction through the below the first sealing device 1 arranged second sealing device 2 sealed in the axial direction, ie covered. Spreading, especially creeping, of hydraulic fluid from a hydraulic chamber (not shown) extending above the sealing means 100 located in an area below the sealing device 100 can therefore be avoided or at least reduced at least by means of the second sealing device 2 in the region of the first gap 1 '.

The same applies to the second gap 2 'of the second sealing device 2 in the opposite direction.

In the 1 illustrated arrangement of first, second and third sealing means 1 2, 3 preferably also prevents or reduces the spread of hydraulic fluid on an inner side of the sealing device 100 , Hydraulic medium from a hydraulic chamber (not shown) above the sealing device 100 can not propagate radially inward in a region of the first gap 1 ', since the third sealing device 3, the first gap 1' of the first sealing device 1 preferably seals in the radial direction, ie covering.

The same applies to the second gap 2 'of the second sealing device. 2

In 2 is a second preferred embodiment of a sealing device 100 with a first, second and third sealing device 1 , 2, 3 and a fuse element 16 shown, the angle of view of the sealing device 100 in 2A and 2 B rotated by 180 °.

As in 2A clearly visible, the fuse element points 16 a first holding nose 16a and a second retaining lug 16b on, which are arranged in the axial direction next to each other or one above the other. Preferably, the first retaining lug 16a integral with the first sealing device 1 and the second holding nose 16b formed or manufactured in one piece with the second sealing device 2. The first and second retaining lugs are preferred 16a . 16b each in the manner, in particular shell-shaped, formed or shaped so that they form a mutual, especially hollow, hemisphere, as in 2 B is clearly visible.

The retaining lugs 16a . 16b preferably extend from the first and second sealing means 1 , 2 from radially inward. In the assembled state of the sealing device 100 grab the retaining lugs 16a . 16b preferably in the third gap 3 'of the third sealing device 3 and thus prevent rotation of the first, second and / or third sealing device 1 , 2, 3 against each other.

In 3 is a third preferred embodiment of a sealing device 100 with a first, second and third sealing device 1 , 2, 3 and a fuse element 16 shown. 3A shows a perspective view of the sealing device 100 and 3B an arrangement of the sealing device 100 in or on a hydraulic piston 101 , in particular a length-adjustable connecting rod.

The fuse element 16 has a locking pin 16c which partially into a first groove 17a the first sealing device 1 and partly into a second groove 17b the second sealing device 2 is pressed. In this case, a radially outer end of the securing pin preferably closes 16c substantially flush with a radially outer surface of the first and second sealing means 1 , 2 off.

The locking pin 16c extends from the first and second sealing means 1 , 2 preferably radially inward and thereby passes through a third gap 3 'of the third sealing means 3. As a result, the locking pin 16c during assembly of the sealing device 100 in a first groove 6 of the hydraulic piston 101 in a locking pin hole 18 introduced, in particular, be pressed. The locking pin hole 18 is preferred in the first groove 6 arranged so that in the locking pin hole 18 introduced locking pin 16c the first, second and / or third sealing device 1 , 2, 3 against rotation in the circumferential direction, in particular against rotation relative to the hydraulic piston 101 , secures.

In an alternative, not shown embodiment, the locking pin 16c instead of the third gap 3 ', a corresponding hole in the third sealing device 3 can also pass through or be pressed into it. This will ensure a particularly secure fit of the locking pin 16c in the third sealing device 3 allows.

4 shows a fourth preferred embodiment of a sealing device 100 with a first, second and third sealing device 1 , 2, 3 and a fuse element 16 , In 4A is a perspective view and in 4B an arrangement of the sealing device 100 in or on a hydraulic piston 101 , in particular a length-adjustable connecting rod shown.

The fuse element 16 has a safety ball 16d on, which partially in a first groove 17a the first sealing device 1 and partly in a second groove 17b the second sealing device 2 is arranged. Preferably, the safety ball 16d also partially arranged in a third gap 3 'of the third sealing device 3. Preferably, the third sealing device 3 in the region of the third gap 3 ', a third groove (not shown), which the safety ball 16d at least partially absorbs.

Preferably, the first and second grooves 17a . 17b formed or shaped in such a way that the safety ball 16d in the assembled state of the sealing device 100 , in particular in a groove 6 of the hydraulic piston 101 , through the first and second groove 17a . 17b is supported radially outside. Alternatively, the fuse ball 16d also by a hydraulic cylinder (not shown), in which the hydraulic piston 101 is slidably mounted radially outwardly supported. Radially inside, the backup group can 16d from the third groove or the bottom of the groove 6 be supported.

In 5 is a preferred embodiment of a hydraulic piston 101 represented, which two in the region of its end faces 4 . 4 ' arranged sealing devices 100 . 100 ' having.

The hydraulic piston 101 is in a hydraulic cylinder 102 an only partially illustrated length adjustable connecting rod 103 arranged in which it is slidably mounted in the axial direction, as indicated by the double-headed arrow. The hydraulic piston 101 and the hydraulic cylinder 102 preferably form a first hydraulic chamber 5 , which with a hydraulic medium, in particular oil, can be fed. The hydraulic medium can preferably be subjected to a predetermined pressure. The thereby on a first end face 4 of the hydraulic piston 101 acting pressure may preferably be a movement of the hydraulic piston 101 effect in the axial direction, so that the first hydraulic chamber 5 or their volume increased. Alternatively, a feed may also be due to inertial and / or acceleration forces on the hydraulic piston 101 respectively. Stuffed oil prevents movement of the hydraulic piston in this case 101 in the opposite direction.

The hydraulic medium in the first hydraulic chamber 5 is in particular acted upon by the predetermined pressure, since a first sealing device 100 leakage of the hydraulic medium from the first hydraulic chamber 5 in a Interspace, in particular gap, between the hydraulic piston 101 and the hydraulic cylinder 102 and / or in a space in the region of the second end face 4 ' of the hydraulic piston 101 , in particular in a second hydraulic chamber (not shown), prevented or at least reduced.

Also, the hydraulic fluid in this second hydraulic chamber, which also from the hydraulic piston 101 and the hydraulic cylinder 102 is formed, can preferably be pressurized, since a second sealing device 100 ' the escape of the hydraulic medium in the intermediate space, in particular gap, between the hydraulic piston 101 and the hydraulic cylinder 102 and / or in the first hydraulic chamber 5 prevented or at least reduced.

Moves the hydraulic piston 101 down, ie the volume of the first hydraulic chamber decreases 5 , the volume increases in the area of the second end face 4 ' of the hydraulic piston 101 arranged second hydraulic chamber and vice versa.

The hydraulic piston 101 has for receiving the first and second sealing device 100 . 100 ' in the area of its two end faces 4 . 4 ' preferably in each case one the lateral surface of the hydraulic piston 101 circumferential first and second groove 6 . 6 ' on. The grooves 6 . 6 ' are preferably formed or shaped such that the sealing devices 100 . 100 ' essentially can be recorded accurately. In particular, a depth of the grooves corresponds 6 . 6 ' substantially the axial cross section of a segment of the annular sealing devices 100 . 100 ' ,

Preferably, the sealing devices protrude 100 . 100 ' in the radial direction at least partially out of the grooves 6 . 6 ' in addition, in particular between 100 μm and 1 μm, preferably between 75 μm and 10 μm, particularly preferably between 50 μm and 20 μm. They are in the grooves 6 . 6 ' arranged, partially protruding from them sealing devices 100 . 100 ' in particular set up as guide elements of the hydraulic piston 101 in the hydraulic cylinder 102 to act. As a result, it is preferably avoided that the hydraulic piston 101 , in particular during a movement of the hydraulic piston 101 , with the hydraulic cylinder 102 interacts, which on the one hand the life of the hydraulic piston 101 and on the other hand, a frictional resistance, during the movement of the hydraulic piston 101 to overcome, at least reduced.

The hydraulic piston 101 points in the axial direction, in particular along an axis of symmetry of the cylindrically shaped hydraulic piston 101 , preferably a blind hole 7 on, in which an internal thread can be cut. The blind hole 7 is preferably adapted to a shaft 8th the length adjustable connecting rod 103 to absorb or the shaft 8th with the hydraulic cylinder 101 , in particular form-fitting and / or non-positive, to connect. For this, the shaft 8th have an external thread, which with the internal thread of the blind hole 7 can interact. Preferably, however, the shaft can also be integral with the hydraulic cylinder 101 be educated.

The hydraulic piston 101 has in the region of its lateral surface preferably between the first and second sealing device 100 . 100 ' arranged mounting recess 9 which is adapted to with a tool for connecting the hydraulic piston 101 with the shaft 8th to interact. The mounting recess 9 For example, as a hexagonal screw, ie as a counterpart of a hexagonal wrench, be formed or shaped, so that the hydraulic piston 101 by means of such a hexagonal wrench on the shaft 8th is screwable.

In the area of the second front side 4 ' of the hydraulic piston 101 is preferably a two-component anti-rotation 10 arranged. A sleeve element 10 ' the anti-twist device 10 is with the shaft 8th , in particular positive and / or frictionally engaged, for example, on the shaft 8th screwed. Alternatively, the sleeve member 10 ' also by means of a grub screw 11 on the shaft 8th be fixed.

The sleeve element 10 ' has on its lateral surface preferably an axially extending guide groove 12 in which a pin element 10 " the anti-twist device 10 intervenes. In this case, the pin element protrudes 10 " preferably in the hydraulic cylinder 102 into it. The elongated shape of the guide groove 12 allows a movement of the sleeve member 10 ' in the axial direction, but reliably prevents rotation of the sleeve member 10 ' , and thus also of the shaft 8th as well as the one with the shaft 8th connected hydraulic piston 101 and / or the small connecting rod eye, in the circumferential direction.

In 6 is a preferred embodiment of a length-adjustable connecting rod 103 shown, with the connecting rod 103 is located in a shortened state with minimum overall length. The connecting rod 103 has at a lower end preferably a large connecting rod eye 13 for connecting the connecting rod 103 with a crankshaft (not shown). At an upper end, which is opposite to the lower end, has the connecting rod 103 preferably a small connecting rod eye 14 on, over which the connecting rod 103 by means of a piston pin (not shown) with a piston (not shown) is connectable.

The small connecting rod eye 14 is preferably via a shaft 8th with a hydraulic piston 101 connected, which in a hydraulic cylinder 102 the connecting rod 103 is arranged axially movable. The hydraulic cylinder 102 is at a the small connecting rod eye 14 facing end preferably with a stop sleeve 15 closed, which at least partially in the hydraulic cylinder 102 be screwed in or can be.

The stop sleeve 15 forms together with the hydraulic cylinder 102 and a sleeve member 10 ' an anti-twist device 10 preferably a second hydraulic chamber 5 ' in an area of the small connecting rod eye 14 facing the second end face 4 ' of the hydraulic piston 101 , The between the stop sleeve 15 , the hydraulic cylinder 102 and the sleeve member 10 ' Spanned volume is preferably chargeable with a hydraulic medium, in particular oil. Is the connecting rod 103 not in a shortened state with minimum total length and becomes the hydraulic medium in the second hydraulic chamber 4 ' subjected to a pressure which is greater than a pressure in a first hydraulic chamber 5 that of the hydraulic piston 101 and the hydraulic cylinder 102 in the area of a first, the big connecting rod eye 13 facing end face 4 of the hydraulic piston 101 is formed, so moves the hydraulic piston 101 axially in the direction of the large connecting rod eye 13 , That of the first hydraulic chamber 5 Spanned volume is due to the shortened condition of the connecting rod 103 not visible with minimum total length in the example shown.

The other way round is preferably the first Hydraulikkamer 5 Chargeable with the hydraulic medium, so that the hydraulic piston 101 in the direction of the small connecting rod eye 14 moves when the pressure prevailing in the first hydraulic chamber pressure is greater than the pressure of the hydraulic medium in the second hydraulic chamber 5 ' and the connecting rod 103 not in an extended state with maximum total length.

Thus, a pressurization of the hydraulic medium in the first or second hydraulic chamber 5 . 5 ' reliable in a corresponding movement of the hydraulic piston 101 results, the hydraulic piston points 101 preferably one in the region of the first end face 4 of the hydraulic piston 101 arranged first sealing device 100 and one in the region of the second end face 4 ' of the hydraulic piston 101 arranged second sealing device 100 ' on. The sealing devices 100 . 100 ' preferably prevent or reduce at least one leakage of the hydraulic medium from the first and / or second hydraulic chamber 5 . 5 ' , so that in the first and / or second hydraulic chamber 5 . 5 ' a predetermined pressure for controlling the position of the hydraulic piston 101 in the axial direction and thus the total length of the length-adjustable connecting rod 103 can build up.

LIST OF REFERENCE NUMBERS

1-3

first, second, third sealing means

1, -3 '

first, second, third gap

o1

Top of the first sealing device

2u

Bottom of the second sealing device

o3

Top of the third sealing device

3u

Bottom of the third sealing device

4, 4 '

first, second end face

5, 5 '

first, second hydraulic chamber

6, 6 '

first, second groove

7

blind

8th

shaft

9

mounting exception

10

twist

10 '

sleeve member

10 "

pin element

11

grub screw

12

guide groove

13

big connecting rod eye

14

small connecting rod eye

15

stop sleeve

16

fuse element

16a, 16b

first, second holding nose

16c

safety pin

16d

securing ball

17a, 17b

first, second groove of the first and second sealing device

18

Safety pin hole

100, 100 '

first, second sealing device

101

hydraulic pistons

102

hydraulic cylinders

103

length adjustable connecting rod

Claims (23)

Sealing device (100) for sealing hydraulic chambers (5, 5 ') of a length-adjustable connecting rod (103), in particular an internal combustion engine, comprising: - A first annular sealing means (1) having a first gap (1 '); a second annular sealing device (2) with a second gap (2 '); a third annular sealing device (3) having a third gap (3 '), the first and second sealing devices (1, 2) resting radially on the third sealing device (3) in such a manner that the first sealing device (1) and the second seal means (2) arranged side by side in an axial direction and the first gap (1 '), the second gap (2') and the third gap (3 ') are respectively displaced from each other in a circumferential direction. Sealing device (100) according to Claim 1 with a securing element (16) which is adapted to fix the sealing devices (1, 2, 3) in the circumferential direction relative to one another. Sealing device (100) according to Claim 2 wherein the securing element (16) has a first retaining lug (16a) arranged on the first sealing device (1) and a second retaining lug (16b) arranged on the second sealing device (2), and wherein the first and second retaining lugs (16a, 16b) is each adapted to intervene in the third gap (3 '). Sealing device (100) according to Claim 2 in which the first sealing device (1) has a first groove (17a) and the second sealing device (2) has a second groove (17b) and the securing element (16) forms parts in the first groove (17a), the second groove (17b) and the third gap (3 ') or a bore of the third sealing device is arranged. Sealing device (100) according to Claim 4 in that the securing element (16) has a securing pin (16c) which passes through the third gap (3 ') or the bore of the third sealing device (3'), engages in the first and second grooves (17a, 17b) and in a locking pin bore (18) of a hydraulic piston (101) is insertable. Sealing device (100) according to Claim 4 in that the securing element (16) has a securing ball (16d) which rests in the third gap (3 ') and in the first and second groove (17a, 17b). Sealing device (100) according to one of the preceding claims, wherein the total axial height of the first and second sealing means (1, 2) in a seated state on the third sealing means (3) at least substantially corresponds to the axial height of the third sealing means (3). Sealing device (100) according to Claim 7 in that the total axial height of the first and second sealing means (1, 2) and the axial height of the third sealing means (3) is between 0.75 mm and 5 mm, preferably between 1 mm and 2 mm, in particular between 1.25 mm and 1 , 75 mm. Sealing device (100) according to one of the preceding claims, wherein an outer diameter of the first and second sealing means (1, 2) each between 15 mm and 25 mm, preferably between 17.5 mm and 22.5 mm, in particular between 19 mm and 21 mm is. Sealing device (100) according to one of the preceding claims, wherein an inner diameter of the first and second sealing means (1, 2) on the one hand and an outer diameter of the third sealing means (3) on the other hand in each case between 14 mm and 24 mm, preferably between 16 mm and 22 mm, in particular between 18 mm and 20 mm. Sealing device (100) according to one of the preceding claims, wherein an inner diameter of the third sealing device (3) is between 13 mm and 23 mm, preferably between 15 mm and 21 mm, in particular between 17 mm and 19 mm. Sealing device (100) according to one of the preceding claims, wherein the first, second and third sealing means (1-3) are each made of spring steel. Sealing device (100) according to one of the preceding claims, wherein the first and the second gap (1 ', 2') are displaced in the circumferential direction by substantially 180 degrees to each other. A sealing device (100) according to any one of the preceding claims, wherein a gap width of the first, second and third gaps (1 '-3') in the seated state of the first and second sealing means (1, 2) on the third sealing means (3) is less than 75 microns, preferably less than 50 microns, in particular less than 10 microns. Hydraulic piston (101), in particular change piston, with at least one sealing device (100) according to one of Claims 1 to 14 , Hydraulic piston (101), in particular after Claim 15 wherein a first sealing device (100) in a region of a first end face (4) of the hydraulic piston (101) and a second sealing device (100 ') in a region of the second end face (4') of the hydraulic piston opposite the first end face (4) (101) is arranged. Hydraulic piston (101) after Claim 16 with a lateral surface which is axially bounded by the first end face (4) and the second end face (4 '), wherein the lateral surface in the region of the first end face (4) has a first groove (6) encircling the lateral surface for receiving the first sealing device (100) and in the region of the second end face (4 ') has a second, circumferential surface groove (6') for receiving the second sealing device (100 '). Hydraulic piston (101) according to one of Claims 15 to 17 with an axially arranged blind hole (7), wherein the hydraulic piston (101) by means of the blind hole (7) with a shaft (8), in particular a length-adjustable connecting rod (103) is connectable. Hydraulic piston (101) after Claim 18 with at least one fastening recess (9) which is arranged on the or a lateral surface of the hydraulic piston (101) and adapted to interact with a tool for connecting the hydraulic piston (101) to the shaft (8). A length adjustable connecting rod (103) for use in a variable compression ratio internal combustion engine comprising a hydraulic cylinder (102) and a hydraulic piston (101) according to any one of Claims 10 to 15 having. Connecting rod (103) after Claim 20 with an anti-rotation device (10) which is adapted to fix a shaft (8) of the connecting rod (103) in a circumferential direction relative to the hydraulic cylinder (102). Connecting rod (103), in particular after Claim 21 , wherein the anti-rotation device (10) in the hydraulic cylinder (102) movable in the axial direction, with the shaft (8) connected sleeve member (10 ') and a radially into the hydraulic cylinder (102) protruding pin member (10 "), which in a on a shell side of the sleeve member (10 ') arranged in the axial direction guide groove (12) of the sleeve member (10') engages. Manufacturing method for a sealing device (100, 100 ') according to one of Claims 1 to 14 in that the first and second sealing means (1, 2) are mounted on the third sealing means (3) in such a manner that the first sealing means (1) is disposed axially adjacent the second sealing means (2) and both a top (o1) of the first seal means (1) together with a top (o3) of the third seal means (3) and a bottom (2u) of the second seal means (2) together with a bottom (3u) of the third seal means (3) is ground flat.

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