• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a length-adjustable connecting rod (6.1) for an internal combustion engine (1), with a first connecting rod part (18.1), a second connecting rod part (19.1) and at least one cylinder-piston unit (20.1) relative to the first connecting rod part (18.1) to adjust the second connecting rod part (19.1). The cylinder-piston unit (20.1) comprises a cylinder bore (22.1), an adjusting piston (21.1) arranged longitudinally movably in the cylinder bore (22.1), at least one first pressure chamber (24.1) provided in the cylinder bore (22.1) and one between the outer wall (39.1) of the adjusting piston (21.1) and the inner wall (38.1) of the cylinder bore (22.1) arranged sealing means (23.1). The sealing device (23.1) comprises at least two piston seals (33.1) which are arranged in separate piston grooves (34.1) formed on the outer wall (39.1) of the adjusting piston (21.1) and in sliding contact with the inner wall (38.1) of the cylinder bore (22.1).
    公开号:AT519305A2
    申请号:T50920/2017
    申请日:2017-11-03
    公开日:2018-05-15
    发明作者:Kai Arens Dr；Riba Zóltan；Bodensteiner Martin；Latz Steffen；Heller Malte
    申请人:Avl List Gmbh；Iwis Motorsysteme Gmbh & Co Kg；
    IPC主号:
    专利说明:

    Length adjustable connecting rod with a cylinder-piston unit with multiple piston seals
    The present invention relates to a length-adjustable connecting rod for an internal combustion engine, comprising a first connecting rod part, a second connecting rod part and at least one cylinder-piston unit for adjusting the first connecting rod part relative to the second connecting rod part, the cylinder-piston unit comprises a cylinder bore in the cylinder bore longitudinally movably arranged adjusting piston, at least one provided in the cylinder bore pressure chamber and arranged between an outer wall of the adjusting piston and an inner wall of the cylinder bore sealing means. Furthermore, the invention relates to an internal combustion engine with such a length-adjustable connecting rod and the use of such a cylinder-piston unit for a length-adjustable connecting rod of an internal combustion engine.
    The thermal efficiency of an internal combustion engine, in particular gasoline engines, is dependent on the compression ratio ε, i. the ratio of the total volume before compression to the compression volume (ε = (stroke volume Vh + compression volume Vc) / compression volume Vc). As the compression ratio increases, the thermal efficiency increases. The increase in the thermal efficiency via the compression ratio is degressive, but still relatively strong in the range of today's usual values.
    In practice, the compression ratio can not be increased arbitrarily, since too high a compression ratio leads to unintentional spontaneous combustion of the combustion mixture due to pressure and temperature increase. This early combustion not only leads to a troubled run and the so-called knocking in gasoline engines, but can also lead to component damage to the engine. In the partial load range, the risk of spontaneous combustion is lower, which, in addition to the influence of ambient temperature and pressure, also depends on the operating point of the engine. Accordingly, a higher compression ratio is possible in the partial load range. In the development of modern internal combustion engines, there are therefore efforts to adjust the compression ratio to the respective operating point of the engine. For the realization of a variable compression ratio (VOR) there are different solutions with which the position of the crank pin or the piston pin of the engine piston changes or the effective length of the connecting rod is varied. There are always solutions for a continuous and discontinuous adjustment of the components. Continuous adjustment allows optimal reduction of CC output and consumption due to a compression ratio that can be set for each operating point.
    In contrast, a discontinuous adjustment with two stages designed as end stops of the adjustment movement allows design and operational advantages and still allows significant savings in consumption and CCVA output compared to a conventional crank mechanism.
    Already the document US 2,217,721 describes an internal combustion engine with a length-adjustable connecting rod with two telescopically movable rod parts, which together form a high-pressure chamber. For filling and emptying of the high-pressure chamber with engine oil and thus to change the length of the connecting rod, a hydraulic adjusting mechanism is provided with a control valve with spring-biased closure element, which is displaceable by the pressure of the engine oil in an open position.
    A discontinuous adjustment of the compression ratio for an internal combustion engine is shown in EP 1 426 584 A1, in which an eccentric connected to the piston pin makes it possible to adjust the compression ratio. In this case, a fixation of the eccentric in one or the other end position of the pivoting area by means of a mechanical locking. DE 10 2005 055 199 A1 likewise discloses the mode of operation of a length-variable connecting rod with which different compression ratios are made possible. The realization is also done here via an eccentric in the small connecting rod, which is fixed in position by two hydraulic cylinders with variable resistance.
    WO 2013/092364 A1 describes a length-adjustable connecting rod for an internal combustion engine with two telescopically movable rod parts, wherein a rod part forms a cylinder and the second rod part forms a longitudinally displaceable piston element. Between the adjusting piston of the first rod part and the cylinder of the second rod part, a high-pressure space is formed, which is supplied via a hydraulic adjusting mechanism with an oil passage and an oil pressure-dependent valve with engine oil. A similar length-adjustable connecting rod for an internal combustion engine with telescopically displaceable rod parts is shown in WO 2015/055582 A2.
    According to WO 2015/055582 A2, the compression ratio in the internal combustion engine should be adjusted by the connecting rod length. The connecting rod length affects the compression volume in the combustion chamber, wherein the stroke volume is determined by the position of the crankshaft journal and the cylinder bore. A short connecting rod therefore results in a lower compression ratio than a long connecting rod with otherwise identical geometrical dimensions, e.g. Piston, cylinder head, crankshaft, valve control etc. In the known length-adjustable connecting rods, the connecting rod length is hydraulically varied between two positions. The entire connecting rod is made in several parts, wherein the change in length is effected by a telescopic mechanism which is adjustable by means of a double-acting hydraulic cylinder. The small connecting rod eye, usually for receiving the piston pin, is connected to a piston rod (telescopic rod part). The associated adjusting piston is axially displaceably guided in a cylinder which is arranged in the connecting rod part with the large connecting rod eye, usually for receiving the crankshaft journal. The adjusting piston separates the cylinder into two pressure chambers, an upper and a lower pressure chamber. These two pressure chambers are supplied via a hydraulic adjusting mechanism with engine oil, wherein its supply of engine oil via the lubrication of the connecting rod bearing takes place. For this purpose, an oil passage from the crankshaft journal over the connecting rod bearing to the connecting rod and there via the check valves of the adjusting mechanism in the pressure chambers is required.
    If the connecting rod is in the long position, there is no engine oil in the upper pressure chamber. The lower pressure chamber, however, is completely filled with engine oil. During operation, the connecting rod is loaded alternately due to the gas and inertial forces on train and pressure. In the long position of the connecting rod, a tensile force is absorbed by the mechanical contact with an upper stop of the adjusting piston. The connecting rod length does not change as a result. An applied compressive force is transmitted via the piston surface to the oil-filled lower pressure chamber. Since the check valve of this chamber prevents the oil return, the oil pressure increases, which can result in the lower pressure chamber very high dynamic pressures of well over 1,000 bar. The connecting rod length does not change. The connecting rod is hydraulically locked in this direction by the system pressure.
    In the short position of the connecting rod, the conditions turn around. The lower pressure chamber is empty, the upper pressure chamber is filled with engine oil. A tensile force causes a pressure increase in the upper pressure chamber. A compressive force is absorbed by a mechanical stop.
    The connecting rod length can be adjusted in two stages by emptying one of the two pressure chambers. For this purpose, one of the two non-return valves in the inlet is bridged by the adjusting mechanism or an associated return channel is opened. By means of these return passages, engine oil can flow into the crankcase independently of the pressure difference between the pressure chamber and the supply device. The respective check valve loses its effect accordingly. The two return channels are opened and closed by a control valve, always exactly one return channel open, the other is closed. The actuator for switching the two return channels is controlled hydraulically by the supply pressure here.
    The space for such a connecting rod is limited both axially and radially. In the crankshaft direction of the space is limited by the bearing width and the distance of the counterweights. In the axial direction is anyway only the space between the small connecting rod for the storage of the piston pin and the large bearing eye for the storage of the crankshaft journal and a possible Verstellhub the connecting rod available.
    The forces to be transmitted by a connecting rod in an internal combustion engine are considerable, which is why the pressures in the pressure chambers of the cylinder-piston unit can be considerable. In view of the high internal pressures in a cylinder-piston unit, the fatigue strength of the materials used is problematic, but also the construction of the components in view of the small installation space.
    Another aspect of a length-adjustable connecting rod with a cylinder-piston unit for use in an internal combustion engine is that the hydraulic adjusting mechanism is usually fed by the engine oil of the engine, the viscosity of which decreases not only with the operating temperature but also with increasing operating time and in the harmful particles are registered in the adjustment mechanism of the connecting rod. In addition to soot particles, which can be produced during combustion in the engine, casting oil particles or chips from the manufacture and processing of the engine are also transported via the engine oil. Regardless of a decrease in viscosity of the engine oil and the particles transported by the engine oil into the adjusting mechanism, the adjusting mechanism of a length-adjustable connecting rod must remain permanently functional.
    In view of the extreme pressure differences in the pressure chambers of a cylinder-piston unit for a length-adjustable connecting rod of well over 1,000 bar and the influence of power transmission via the connecting rod to the crankshaft on the performance of the internal combustion engine, in conventional length-adjustable connecting rods touching sealing devices or constructive trained seals used. A leakage from the respective locked pressure chamber leads to engagement of the adjusting piston in the respective pressure chamber, whereby an amount of work is dissipated according to the force on the adjusting piston and the path of the adjusting piston, resulting in power loss of the internal combustion engine. This power loss is deducted from the improved thermal efficiency of the internal combustion engine by a variable compression ratio according to the respective constructions of the cylinder-piston units. In conventional length-adjustable connecting rods with a cylinder-piston unit are used as sealing devices usually simple gap seals. In contrast to contact seals, which prevent leaks as contacting sealing devices, gap seals have a certain leakage due to the design. The advantages of gap seals are the ease of installation, due to the smaller number of components and a smaller space of the cylinder-piston unit. In contrast, the system-inherent leakage in gap seals causes not only a loss of power but also a heating of the system. Contact seals, such as piston or rod seals, which can be arranged between the longitudinally displaceable components of a cylinder-piston unit, can prevent a leakage of engine oil from the pressure chamber almost completely and avoid a corresponding loss of power. However, contact seals are very sensitive to soot particles and chips in the engine oil, which can lead to severe damage to the surfaces of the sealing device and ultimately to a malfunction or failure of the sealing device. This hazard increases with higher system pressures, as the particles from the engine oil are increasingly conveyed between the piston skirt and the cylinder wall and dig there at the sealing surfaces.
    Although piston lifting machines are well known in many fields of technology and piston engines are constantly being optimized, improved and developed in the automotive industry, the sealing situation in cylinder-piston assemblies of length-adjustable connecting rods continues to be unsatisfactory, in spite of extensive development and research work, in particular with regard to the necessary service life of length-adjustable connecting rods over the entire life of internal combustion engines. In contrast to conventional reciprocating engines touching piston seals are exposed in a cylinder-piston unit length adjustable connecting rods in addition to wear from the metallic contact increased load by the small available space, the extreme temperature load by extremely high pressures and changing force directions and the pollution of the engine oil with soot particles and chips. This leads to rapid wear of the piston seals and grooves in the walls of the cylinder-piston unit and ultimately to a failure of the sealing device and power loss of the internal combustion engine. Accordingly, in recent developments of length-adjustable connecting rods preferred gap seals are used, which allow at least the advantage of a smaller number of components of a small space. Functionally such gap seals in cylinder-piston units length-adjustable connecting rods are still subject to significant wear, since the gap between the cylinder and adjusting piston to achieve a sufficient extreme pressure difference for the sealing effect must be relatively small. Regardless of whether a contactless gap seal or a contact seal is used as the sealing device for a cylinder-piston unit, the high system pressure in the cylinder-piston unit causes soot particles and chips from the engine oil to penetrate between the cylinder wall and the piston skirt and jam between the sealing surfaces, which can lead to severe damage to the surfaces and ultimately to wear and failure of the cylinder-piston unit.
    The present invention is therefore based on the object to provide a length-adjustable connecting rod with a cylinder-piston unit with an improved sealing device, which allows despite improved pressure differences and small space, an improved durable sealing effect.
    The object is achieved in that the sealing device comprises at least two piston seals, each piston seal is arranged in a separate circumferential groove on the outer wall of the adjusting and is in sliding contact with the inner wall of the cylinder bore. The provision of at least two piston seals reduces the pressure drop which, due to the extremely high system pressures, must be dissipated via each of the separate piston seals and accordingly reduces the risk of particulate from the engine oil and subsequently damaging the seal surface by these particles. In addition, the gradual reduction of the high system pressures in the cylinder-piston unit allows the use of simpler and less expensive piston seals with a flatter construction, which can be used in the small available space of a cylinder-piston unit without constructive compensation measures. For a secure pressure buildup, the piston seals are each arranged in a separate circumferential groove on the outer wall of the adjusting, which not only ensures a seal of the piston seal against the adjusting, but also despite the high system pressures and the relative movement relative to the inner wall of the cylinder bore with little effort enables safe positioning of the piston seal. To enhance the positive effects of a gradual pressure reduction and limitations of the pressure drop acting on the individual piston seals, the sealing device may comprise three, preferably at least four piston seals. Usually, the adjusting piston and the cylinder bore of the cylinder-piston unit are rotationally symmetrical, but not limited to such a geometric shape. A length-adjustable connecting rod according to the present invention also includes oval, polygonal or other cross-sectional shapes of the adjusting piston and the cylinder bore of the cylinder-piston unit.
    Preferably, the piston seals of the sealing device are designed as double-acting piston seals. This not only the alternating relative movement between the
    Adjustment piston and the cylinder bore easier and avoids a negative impact on the sealing effect, but also allows a two-sided effect of the cylinder-piston unit. An expedient design of the piston seals provides that the double-acting piston seals are formed in two parts, wherein the two-part piston seals each have a positioning ring and a sliding ring, preferably made of plastic. The positioning ring, usually a dimensionally stable O-ring, allows a secure arrangement of the piston seal in bias against the circumferential groove in the outer wall of the adjusting. In contrast, the sliding ring, preferably made of a low-friction plastic material, with a rectangular body and a center in the direction of the inner wall of the cylinder bore protruding sealing lip allows a good seal with high pressure resistance and a good low friction sliding against the inner wall of the cylinder bore.
    A useful embodiment provides that the sealing device comprises a scraper, wherein the scraper is arranged at a pressure chamber facing the end of the outer wall of the adjusting piston. The scraper which is arranged between the filled with engine oil pressure chamber and the first piston seal in the direction of the pressure chamber, prevents or reduces the entry of soot particles and chips from the engine oil in the gap between the adjusting piston and the cylinder bore and finally between the piston seal and inner wall of the cylinder bore. This reduces the risk of wear, damage and failure of the sealing device and thus ultimately significantly increases the service life of the cylinder-piston unit.
    A particular embodiment provides that the adjusting piston of the cylinder-piston unit is designed as a double-acting adjusting piston, wherein the longitudinally movably arranged in the cylinder bore adjusting piston forms a first pressure chamber and a second pressure chamber for receiving engine oil and bounded on one side. A two-way adjusting piston allows the adjustment of the stroke of the piston rod both in the direction of a larger compression ratio and in the direction of a lower compression ratio with a single cylinder-piston unit. So it is the same adjusting, unlike in DE 10 2005 055 199 A1, used for bidirectional adjustment of the piston stroke, and the compression ratio. Conveniently, here a stepped piston can be used, by means of which the larger end face is pressed with appropriate pressurization, the connecting rod in its extended position. Due to the prevailing force conditions in an internal combustion engine, the smaller end face usually suffices for the adjustment in the opposite direction. In this case, the adjusting piston at the first pressure chamber and the second pressure chamber facing ends of the outer wall, each having a scraper.
    A further embodiment provides that the adjusting piston has at a second end face which delimits the second pressure chamber, a piston rod which extends through a rod bore of the cylinder-piston unit, wherein at least two rod seals are provided, each rod seal in a circumferential groove is arranged in the rod bore and is in sliding contact with the piston rod. Due to the two separate rod bores, which are arranged securely in the separate circumferential grooves in the rod bore, a pressure reduction of the high system pressure can be carried out in several stages in the area of the piston rod and correspondingly simple design and cost-effectively manufactured rod seals can be used. Here are the rod seals for a secure sealing function and the mobility of the piston rod against the rod bore with the piston rod in sliding contact. It makes sense to provide a rod scraper, wherein the rod scraper is arranged on a second pressure chamber facing the end of the rod bore. The rod scraper thereby prevents inputs of soot particles and chips from the engine oil between the piston rod and the rod bore and thus avoids wear, damage and ultimately failure of the sealing device between the piston rod and rod bore of the cylinder-piston unit. For a simple construction of the length-adjustable connecting rod, the first connecting rod part can be connected to the adjusting piston of the cylinder-piston unit and the second connecting rod part can have the cylinder bore of the cylinder-piston unit.
    Furthermore, the invention relates to the use of a cylinder-piston unit with a sealing device for a length-adjustable connecting rod of an internal combustion engine with a first connecting rod and a second connecting rod, which are adjustable by means of the cylinder-piston unit to the first connecting rod relative to to move second connecting rod, the cylinder-piston unit comprises a cylinder bore, a longitudinally movably arranged in the cylinder bore piston, at least one provided in the cylinder bore pressure chamber and arranged between the outer wall of the adjusting piston and the inner wall of the cylinder bore sealing means, wherein the sealing means at least comprises two piston seals, each piston seal is arranged in a separate circumferential on the outer wall of the adjusting piston groove and is in sliding contact with the inner wall of the cylinder bore. The use of multiple piston seals in the cylinder-piston unit of a length-adjustable connecting rod allows despite the extremely high system pressure and the relatively small size of the cylinder-piston unit a good seal of the pressure chamber and the gradual reduction of the high system pressure with the use of piston seals small dimensions. In this case, the actuation of the cylinder-piston unit by means of acting on the connecting rod gas and mass forces of the internal combustion engine, while the position of the Pleuelteile is locked by the present in the at least one pressure chamber engine oil.
    In a further aspect, the invention relates to an internal combustion engine having at least one reciprocating piston and having at least one adjustable compression ratio in a cylinder and a length-adjustable connecting rod connected to the reciprocating piston according to the above-described embodiments. Preferably, all the reciprocating piston of an internal combustion engine are equipped with such a length-adjustable connecting rod, but this is not required. The fuel economy of such an internal combustion engine can be considerable and up to 20% if, depending on the respective operating state, the compression ratio is adjusted accordingly. Conveniently, the cylinder-piston unit of the length-adjustable connecting rod can be connected to the engine oil of the internal combustion engine. Thus, existing in the engine oil circuit pressures for adjusting and locking the adjusting piston in the cylinder bore of the cylinder-piston unit can be used. In addition, the adjustment mechanism of the length-adjustable connecting rod can be controlled by means of the pressurized engine oil.
    Another modification provides that the system pressure of the engine oil in the pressure chamber of the cylinder-piston unit is between 1000 bar and 3000 bar, preferably between 2000 and 3000 bar. The limitation of the system pressure allows the safe structural design of the inner diameter of the cylinder bore and the wall thickness of the cylinder, and thus allows a safe structural design of the length-adjustable connecting rod according to the invention.
    According to a further development, a control drive can be provided with at least one timing chain, a tensioning and / or guide rail, and / or a chain tensioner, which connects the crankshaft to the at least one camshaft of the internal combustion engine. The timing drive is important because it can have a significant influence on the dynamic load of the engine and thus also on the length-adjustable connecting rod. This is preferably designed so that no excessive dynamic forces are introduced via the control drive. Alternatively, such a timing drive can also be formed with a spur gear or a drive belt, for example a toothed belt, which is prestressed by means of a tensioning device with tensioning roller.
    In the following, an embodiment will be explained in more detail with reference to a drawing. Show it:
    1 shows a schematic cross section through an internal combustion engine,
    2 is a schematic representation of the length-adjustable connecting rod of FIG. 1 in a partially sectioned illustration,
    3 shows a sectional view of an embodiment of an adjusting piston of the cylinder-piston unit from FIG. 2, FIG.
    4 shows a sectional view of a further embodiment of an adjusting piston of the cylinder-piston unit from FIG. 2.
    In Fig. 1, a combustion engine (gasoline engine) 1 is shown in a schematic representation. The internal combustion engine 1 has three cylinders 2.1, 2.2 and 2.3, in each of which a reciprocating piston 3.1, 3.2, 3.3 moves up and down. Furthermore, the internal combustion engine 1 comprises a crankshaft 4, which is rotatably mounted by means of crankshaft bearings 5.1 - 5.4. The crankshaft 4 is connected by means of the connecting rods 6.1, 6.2 and 6.3 respectively with the associated reciprocating piston 3.1, 3.2 and 3.3. For each connecting rod 6.1,6.2 and 6.3, the crankshaft 4 an eccentrically arranged crankshaft journals 7.1,7.2 and 7.3. The large connecting rod 8.1, 8.2, and 8.3 is respectively mounted on the associated crankshaft journal 7.1.7.2 and 7.3. The small connecting rod 9.1, 9.2 and 9.3 is respectively mounted on a piston pin 10.1,10.2 and 10.3 and so pivotally connected to the associated reciprocating 3.1, 3.2 and 3.3. The terms small connecting rod 9.1.9.2 and 9.3 and large connecting rod 8.1.8.2 and 8.3 neither an absolute nor relative size assignment refer to, but they are only used to distinguish the components and assignment to the engine shown in Fig. 1. Accordingly, the dimensions of the diameter of the small connecting rods 9.1, 9.2 and 9.3 may be smaller, equal to or greater than the dimensions of the diameter of the large connecting rods 8.1, 8.2, and 8.3.
    The crankshaft 4 is provided with a crankshaft sprocket 11 and coupled to a camshaft sprocket 13 by means of a timing chain 12. The camshaft sprocket 13 drives a camshaft 14 with its associated cams for actuating the intake and exhaust valves (not shown in detail) of each cylinder 2.1, 2.2 and 2.3. The slack side of the timing chain 12 is tensioned by means of a pivotally mounted clamping rail 15 which is pressed by means of a chain tensioner 16 to this. The Zugtrum the timing chain 12 can slide along a guide rail. The essential operation of this control drive including the fuel injection and ignition by spark plug is not explained in detail and assumed to be known. The eccentricity of the crankshaft journals 7.1, 7.2 and 7.3 are the decisive
    Stroke Ηκ ago, especially if, as in the present case, the crankshaft 4 is arranged exactly centrally below the cylinders 2.1., 2.2 and 2.3. The reciprocating piston 3.1 is shown in Fig. 1 in its lowermost position, while the reciprocating piston 3.2 is shown in its uppermost position. The difference results in the present case, the stroke Hk. The remaining height Hc (see cylinder 2.2) gives the remaining compression height in cylinder 2.2. In conjunction with the diameter of the reciprocating piston 3.1, 3.2 or 3.3 or the associated cylinder 2.1, 2.2 and 2.3 results from the stroke Hk the stroke volume Vh and from the remaining compression height Hc is calculated, the compression volume Vc. Of course, the compression volume Vc significantly depends on the design of the cylinder cover. From these volumes Vh and Vc, the compression ratio ε results. In detail, the compression ratio ε is calculated from the sum of the stroke volume Vh and the compression volume Vc divided by the compression volume Vc. Today's values for gasoline engines are between 10 and 14 for ε.
    Thus, depending on the operating point (η, T, throttle position) of the internal combustion engine 1, the compression ratio ε can be adjusted according to the invention, the connecting rods 6.1,6.2 and 6.3 designed adjustable in length. As a result, can be driven in the partial load range with a higher compression ratio than in the full load range.
    In Fig. 2, the length-adjustable connecting rod 6.1 is exemplified, which is configured identically to the connecting rods 6.2 and 6.3. The description therefore applies accordingly. The connecting rod 6.1 has a connecting rod head 17.1 with the said small connecting-rod eye 9.1, a first connecting rod part 18.1, which is guided telescopically in a second connecting rod part 19.1. The relative movement of the first connecting rod part 18.1 in the longitudinal direction to the second connecting rod part 19.1 takes place by means of a cylinder-piston unit 20.1 with an adjusting piston 21.1. and a cylinder bore 22.1 and a sealing device 23.1 between the adjusting piston 21.1 and the cylinder bore 22.1. At the second connecting rod part 19.1, a lower bearing shell 19b.1 is arranged, which surrounds the large connecting rod eye 8.1 together with the lower region of the second connecting rod part 19.1. The lower bearing shell 19b. 1 and the second connecting rod 19.1 are usually connected to each other by means of fastening means. The lower end of the first connecting rod part 18.1 is connected to the adjusting piston 21.1, which is guided displaceably in the cylinder bore 22.1 of the second connecting rod part 19.1. At the upper end, the second connecting rod part 19.1 has a cover 19a.1, through which the first connecting rod part 18.1 is guided and sealed. Thus, the cover 19a.1 seals the cylinder bore 22.1 in total. The adjusting piston 21.1 is designed as a stepped piston. Below the adjusting piston 21.1, a first pressure chamber 24.1 is formed with a circular cross-section and above the adjusting piston 21.1, an annular second pressure chamber 25.1 is formed. The adjusting piston 21.1 and the cylinder bore 22.1 are part of an adjusting mechanism for changing the connecting rod length. The adjusting mechanism also includes a hydraulic circuit 26.1 described in more detail below, which is correspondingly adapted for an inlet and outlet of the hydraulic fluid into and out of the pressure chambers 24.1 and 25.1 and thus for a fixing of the adjusting piston 21.1 actuated by the forces acting on the connecting rod 6.1 provides.
    In the present embodiment, the portion of the second connecting rod 19.1 in the area of the pressure chambers 24.1 and 25.1 and the adjusting piston 21.1 in cross-section annular (with the exception of any existing hydraulic fluid lines) configured. Other geometric dimensions are conceivable. Accordingly, here the wall thickness Dw results from the associated outer radius ra of the upper portion of the second connecting rod part 19.1 minus the inner radius n of the cylinder bore 22.1. In such a symmetrical embodiment, the wall thickness Dw over the circumference of the second connecting rod 19.1 uniformly thick and the stresses in the material of the second connecting rod 19.1 uniformly low, so that due to a relatively large piston diameter for the adjusting 21.1 occurring in the connecting rod 6.1 maximum system pressure in manageable limits remains.
    In the following, the hydraulic circuit 26.1 used in the connecting rod 6.1 will be explained in more detail with reference to FIG. The adjusting piston 21.1 of the cylinder-piston unit 20.1 is designed as a stepped piston. Under a stepped piston is generally understood to mean a two-sided piston with different sized effective surfaces. A first end face 27.1 is circular in shape and associated with the first pressure chamber 24.1. A second end face 28.1 is designed annular and associated with the second pressure chamber 25.1. The hydraulic circuit 26.1 is operated with engine oil. For this purpose, an oil supply channel 29.1 communicates with the large connecting rod eye 8.1 in connection, whereby motor oil of the hydraulic circuit 26.1 can be supplied or optionally flows out of this. From the oil supply channel 29.1 a Rückströmdrossel 30.1 is provided with a check valve and a throttle connected in parallel thereto. From the Rückströmdrossel 30.1 from the engine oil passes through the channel 31.1 to a control valve 32.1. The control valve 32.1 comprises a control piston 32a. 1, which is against a compression spring 32b. 1 is guided displaceably.
    From the first pressure chamber 24.1 leads a return channel 40.1 to the control valve 32.1. An isolatable by a check valve 41.1 oil passage 42.1 is also in communication with the control valve 32.1 and leads to the first pressure chamber 24.1. The first return passage 40.1 is in the position of the actuating piston 32a shown in FIG. 1 closed. Oil from the first pressure chamber 24.1 can not escape due to the closed check valve 41.1. The adjusting piston 21.1 moves or is in the final extended upper position and is hydraulically locked there. As a result, the connecting rod 6.1 is in its extended position. From the second pressure chamber 25.1 leads a return line 43.1 to the control valve 32.1. In the position of the control valve 32.1 shown in FIG. 2, engine oil can flow out of the second pressure chamber 25.1 via the return line 43.1 and the control valve 32.1 as well as the outlet 44.1 into the crankcase. In the outgoing from the second pressure chamber 25.1 to the control valve 32.1 oil passage 45.1 another check valve 46.1 is arranged.
    However, if the pressure of the engine oil flowing into the hydraulic circuit 26.1 is now increased via the oil pump of the internal combustion engine, the actuating piston 32a.1 in the control valve 32.1 is displaced against the force of the compression spring 32b.1. As a result, the first return passage 40.1 is opened and the engine oil can flow out of the first pressure chamber 24.1 via the channel 31.1 and the return flow throttle 30.1. As a result, the adjusting piston 21.1 decreases. At the same time, the return line 43.1 is closed and filled via the oil passage 45.1 and the check valve 46.1 of the second pressure chamber 25.1 with engine oil. As soon as the adjusting piston 21.1 bears against the lower stop, the adjusting piston 21.1 is hydraulically locked in this position, as long as a sufficient pressure is applied to the control valve 32.1, and the connecting rod 6.1 assumes its short position. This retracted position is advantageous at full load, whereas the extended position shown in FIG. 2 for the partial and low load operation is advantageous. With regard to the further mode of action and operation, reference is additionally made to WO 2015/055582 A2, which describes in detail the adjustment mechanism shown here and variants thereof, which may also be used.
    Figure 3 shows a sectional view of the cylinder-piston unit 20.1 of the longitudinally adjustable connecting rod 6.1 of Figure 2 with a two-stage adjusting piston 21.1 which is longitudinally displaceable in the cylinder bore 22.1. The sealing device 23.1 provided between the inner wall 38.1 of the cylinder bore 22.1 and the outer wall 39.1 of the adjusting piston 21.1 comprises two piston seals 33.1, which are each arranged in a separate circumferential piston groove 34.1 in the outer wall 39.1 of the adjusting piston 21.1. The piston seals 33.1 fixed in position on the adjusting piston 21.1 and sealed with respect to the outer wall 39.1 of the adjusting piston 21.1 are in sliding contact with the inner wall 38.1 of the cylinder bore 22.1. Accordingly, the piston seals 33.1 seal the first pressure chamber 24.1 and prevent the engine oil from passing out of the first pressure chamber 24.1 through the gap 35.1 between the outer wall 38.1 of the adjusting piston 21.1 and the inner wall 39.1 of the cylinder bore 22.1. The piston seals 33.1 can according to the
    Position of the bidirectionally acting adjusting piston 21.1 both in the direction of the first pressure chamber 24.1 and in the direction of the second pressure chamber 25.1 as a double-acting piston seals 33.1 achieve a seal. The piston seals 33.1 are formed in two parts with a positioning ring, which is arranged with a bias in the piston groove 34.1 and a secure seal causes, as with a sliding ring of a low-friction plastic material despite the sliding contact with the inner wall 38.1 of the cylinder bore 22.1 with an in acting both directions sealing lip allows a good seal against the inner wall 38.1.
    In the extended position of the length-adjustable connecting rod 6.1 shown in FIG. 2 and FIG. 3, a very high system pressure of significantly more than 1,000 bar prevails in the first pressure chamber 24. 1 during the compression and combustion phase in the first cylinder 2. 1 of the internal combustion engine 1. By using a plurality of piston seals 33.1, the pressure reduction in the sealing device 23.1 between the first pressure chamber 24.1 and the second pressure chamber 25.1, which is in the extended position of the connecting rod 6.1 at atmospheric pressure, takes place in several steps corresponding to the number of piston seals 33.1. The reduction of the pressure acting on the single piston seal 33.1 enables the use of piston seals 33.1 with a reduced pressure load capacity compared to the high system pressure.
    The first connecting rod part 18.1 comprises a piston rod 18a which extends in the direction of the axis of the first connecting rod part 18.1 from the second end face 28.1 of the adjusting piston 23.1 in the direction of the small connecting rod eye 9.1. As can be seen in FIG. 3, the piston rod 18a.1 extends through a rod bore 36.1 in the cover 19a.1 of the second connecting rod part 19.1, which delimits the cylinder bore 22.1 in the direction of the small connecting rod eye 9.1. In the rod bore 36.1 are spaced apart two circumferential bore grooves 37.1. provided, in each of which a rod seal 47.1 is arranged. The rod seals 47.1 sit under a bias in the bore grooves 37.1 in order to achieve the best possible sealing effect between the rod seal 47.1 and the rod bore 36.1. Similar to the piston seals 33.1, the rod seals 47.1 can be constructed in two parts, with an externally arranged positioning ring and an inner slide ring made of plastic, which is in sliding contact with the piston rod 18a.1 to securely seal the second pressure chamber 25.1 and a gradual reduction of the system pressure in allow second pressure chamber 25.1.
    FIG. 4 shows a further embodiment of an adjusting piston 21.1 of the cylinder-piston unit 20.1 of the length-adjustable connecting rod 6.1 from FIG. 2 in a sectional view. This adjusting piston 21.1 is provided on its outer wall 39.1 with six mutually spaced piston grooves 34.1, wherein in the four central piston grooves 34.1 four mutually spaced piston seals 33.1 are arranged. Since the piston seals 33.1 are each arranged at a distance from each other in separate piston grooves 34.1, both a good sealing effect between the piston seals 33.1 and the outer wall 39.1 of the adjusting 21.1 is achieved, as well as in conjunction with the sliding contact between the piston seals 33.1 and the inner wall 38.1 of the cylinder bore 22.1 allows a gradual pressure reduction of the high system pressure in the first pressure chamber 24.1 and second pressure chamber 25.1. By reducing the pressure drop to be realized by the individual piston seals 33.1, it is also possible to use piston seals 33.1 with a mean maximum permissible pressure.
    In the first end face 27.1 and the second end face 28.1 adjacent piston grooves 34.1 on the outer wall 39.1 of the adjusting 21.1 scrapers are provided 48.1, the movement of the adjusting piston 21.1 in the cylinder bore 22.1 penetration of particles from the engine oil into the gap 35.1 between adjusting piston 21.1. and prevent cylinder bore 22.1. The engine oil scraper 48.1 is securely positioned in the located at the ends of the outer wall 39.1 of the adjusting piston 21.1 piston grooves 34.1. In contrast to gap seals takes place in this contacting sealing device 23.1, the pressure drop in stages over several piston seals 33.1, so that the scrapers 48.1 are not sucked into a movement of the adjusting piston 21.1 in the gap 35.1.
    Also between the rod seals 47.1 in the bore grooves 37.1 of the rod bore 36.1 and the second pressure chamber 25.1 a further scraper 48.1 is provided, which is also arranged in a bore groove 37.1 and prevents the penetration of particles from the engine oil between the rod bore 36.1 and piston rod 18a.1.
    List of Reference Symbols I. Internal combustion engine 2.1.2.2.2.3 Cylinder 3.1.3.2.3.3 Reciprocating piston 4 Crankshaft 5.1.5.2.5.3.5.4 Crankshaft bearing 6.1.6.2.6.3 Connecting rod 7.1.7.2.7.3 Crankshaft journal 8.1.8.2.8.3 Large connecting rod 9.1.9.2.9.3 Small Connecting rod eye 10.1.10.2.10.3 Piston pin II Crankshaft chain wheel 12 Timing chain 13 Camshaft sprocket 14 Camshaft 15 Clamping rail 16 Chain tensioner 17.1 Connecting rod end 18.1 First connecting rod part 18a.1 Piston rod 19.1 Second connecting rod part 19a.1 Cover 19b. 1 bearing shell 20.1 cylinder-piston unit 21.1 adjusting piston 22.1 cylinder bore 23.1 sealing device 24.1 first pressure chamber 25.1 second pressure chamber 26.1 hydraulic circuit 27.1 first end side 28.1 second end side 29.1 oil supply channel 30.1 return flow restrictor 31.1 channel 32.1 control valve 32a.1 control piston 32b.1 compression spring 33.1 piston seal 34.1 piston groove 35.1 Gap 36.1 Bar bore 37.1 Bore groove 38.1 Inner wall 39.1 Outer wall 40.1 Return channel 41.1 Check valve 42.1 Oil channel 43.1 Return line 44.1 Outlet 45.1 Oil channel 46.1 Check valve 47.1 Rod seal 48.1 Oil scraper
    Dw wall thickness
    Vh stroke volume
    Vc Compression volume HC Compression height HK Stroke ri Inner diameter ra Outer diameter S Gap ε Compression ratio n Speed T Temperature
    权利要求:
    Claims (14)
    [1]
    1. length-adjustable connecting rod (6.1) for an internal combustion engine (1), in particular a gasoline engine, with a first connecting rod (18.1) and a second connecting rod (19.1), the first connecting rod (18.1) has a small connecting rod (9.1) for receiving a piston pin (10.1) and the second connecting rod part (19.1) has a large connecting rod eye (8.1) for receiving a crankshaft journal (7.1), wherein the first connecting rod part (18.1) relative to the second connecting rod part (19.1) is movable to the distance between the large connecting rod eye (8.1) and the small connecting rod eye (9.1) and with at least one cylinder-piston unit (20.1) to adjust the first connecting rod part (18.1) relative to the second connecting rod part (19.1), the cylinder-piston unit ( 20.1) comprises a cylinder bore (22.1), an adjusting piston (21.1) arranged longitudinally movably in the cylinder bore (22.1), at least one first pressure chamber (24.1) provided in the cylinder bore (22.1) for receiving engine oil of the internal combustion engine, the pressure chamber (24.1) is bounded on one side by the movable adjusting piston (21.1), and a sealing device (23.1) arranged between an outer wall (39.1) of the adjusting piston (21.1) and an inner wall (38.1) of the cylinder bore (22.1) characterized in that the sealing device (23.1) comprises at least two piston seals (33.1), each piston seal (33.1) being arranged in a separate piston groove (34.1) encircling the outer wall (39.1) of the adjusting piston (21.1) and communicating with the inner wall (38.1). the cylinder bore (22.1) is in sliding contact.
    [2]
    2. Length-adjustable connecting rod (6.1) according to claim 1, characterized in that the sealing device (23.1) comprises at least three, preferably at least four piston seals (33.1).
    [3]
    3. Length-adjustable connecting rod (6.1) according to claim 1 or 2, characterized in that the piston seals (33.1) of the sealing device (23.1) are designed as double-acting piston seals (33.1).
    [4]
    4. Length-adjustable connecting rod (6.1) according to claim 3, characterized in that the double-acting piston seals (33.1) are formed in two parts, wherein the two-part piston seals (33.1) each have a positioning ring and a sliding ring, preferably made of plastic.
    [5]
    5. Length-adjustable connecting rod (6.1) according to one of claims 1 to 4, characterized in that the sealing device (23.1) comprises a scraper (48.1), wherein the scraper (48.1) at one of the first pressure chamber (24.1) facing the end of the outer wall ( 39.1) of the adjusting piston (21.1) is arranged.
    [6]
    6. Length-adjustable connecting rod (6.1) according to one of claims 1 to 5, characterized in that the adjusting piston (21.1) of the cylinder-piston unit (20.1) is designed as a bidirectional adjusting piston (21.1), wherein in the cylinder bore (22.1 ) longitudinally movably arranged adjusting piston (21.1) forms a first pressure chamber (24.1) and a second pressure chamber (25.1) for receiving engine oil and each limited on one side.
    [7]
    7. Length-adjustable connecting rod (6.1) according to claim 6, characterized in that the adjusting piston (21.1) on a second end face (28.1), which limits the second pressure chamber (25.1), a piston rod (18a.1), extending through a Bar bore (36.1) of the cylinder-piston unit (20.1) extends, wherein at least two rod seals (47.1) are provided, each rod seal (47.1) in a circumferential groove (37.1) in the rod bore (36.1) is arranged and with the piston rod (18a.1) is in sliding contact.
    [8]
    8. Length-adjustable connecting rod (6.1) according to claim 7, characterized in that a scraper (48.1) is provided, wherein the scraper (48.1) at a second pressure chamber (25.1) facing the end of the rod bore (36.1) is arranged.
    [9]
    9. Length-adjustable connecting rod (6.1) according to one of claims 1 to 7, characterized in that the first connecting rod part (18.1) with the adjusting piston (21.1) of the cylinder-piston unit (20.1) is connected and the second connecting rod part (19.1) Cylinder bore (22.1) of the cylinder-piston unit (20.1) has.
    [10]
    10. Use of a cylinder-piston unit (20.1) with a sealing device (23.1) for a length-adjustable connecting rod (6.1) of an internal combustion engine (1) with a first connecting rod part (18.1) and a second connecting rod part (19.1), which by means of the cylinder Piston unit (20.1) are adjustable to move the first Pleuelteil (18.1) relative to the second Pleuelteil (19.1), the cylinder-piston unit (20.1) comprises a cylinder bore (22.1), one in the cylinder bore (22.1) along movably arranged adjusting piston (21.1), at least one in the cylinder bore (22.1) provided first pressure chamber (24.1) and between the outer wall (39.1) of the adjusting piston (21.1) and the inner wall (38.1) of the cylinder bore (22.1) arranged sealing means (23.1) , characterized in that the sealing device (23.1) comprises at least two piston seals (33.1), wherein each piston seal (33.1) in a separate on the outer wall (39.1) of the Verstellko Lbens (21.1) is arranged circumferential piston groove (34.1) and is in sliding contact with the inner wall (38.1) of the cylinder bore (22.1).
    [11]
    11. internal combustion engine (1) with at least one reciprocating piston (3.1,3.2,3.3) and with at least one adjustable compression ratio in a cylinder (2.1,2.2,2.3) and connected to the reciprocating piston (3.1,3.2,3.3) length-adjustable connecting rod (6.1 ) (6.1,6.2,6.3) according to one of claims 1 to 9.
    [12]
    12. internal combustion engine (1) according to claim 11, characterized in that the cylinder-piston unit (20.1) of the length-adjustable connecting rod (6.1,6.2,6.3) to the engine oil hydraulics of the internal combustion engine (1) is connected.
    [13]
    13. internal combustion engine (1) according to claim 11 or 12, characterized in that the system pressure of the engine oil in the first pressure chamber (24.1) of the cylinder-piston unit (20.1) between 1,000 and 3,000 bar, preferably between 2,000 and 2,500 bar is.
    [14]
    14. internal combustion engine (1) according to one of claims 11 to 13, characterized in that a timing drive with at least one timing chain (12), a clamping and / or guide rail (15), and / or a chain tensioner (16) is provided the crankshaft (4) with the at least one camshaft (14) of the internal combustion engine (1) connects.
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    同族专利:
    公开号 | 公开日
    DE102016120967A1|2018-05-03|
    AT519305B1|2019-04-15|
    CN110199096A|2019-09-03|
    WO2018083256A1|2018-05-11|
    AT519305A3|2019-03-15|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE102016120967.8A|DE102016120967A1|2016-11-03|2016-11-03|Length adjustable connecting rod with a cylinder-piston unit with multiple piston seals|
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