DE102017217474A1 - Length adjustable connecting rod for a reciprocating engine, reciprocating engine and vehicle - Google Patents

Abstract

The present invention relates to a length-adjustable connecting rod for a reciprocating piston engine, a reciprocating piston engine with such a connecting rod and a vehicle with such a reciprocating piston engine, wherein the connecting rod is a hydraulic Längenverstellvorrichtung (20) for adjusting an effective connecting rod length (L) of the connecting rod and a hydraulic medium supply line (30). for hydraulic supply of hydraulic medium to the length adjustment device (20), wherein the length adjusting device (20) at least a first hydraulic cylinder (21), at least one piston (22) and a first hydraulic working space (23) and a second hydraulic working space (24), and wherein the connecting rod has at least one second hydraulic cylinder (80) with a mass piston (81) for generating an additional hydraulic pressure portion in the first hydraulic cylinder (21) of the length adjustment device (20), wherein the mass force piston (81) by an inertia force occurring in the second Hydrauli Cylinder (80) is displaceable.

Description

The present invention relates to a length-adjustable connecting rod for a reciprocating engine, in particular for a reciprocating internal combustion engine, wherein the connecting rod has a hydraulic Längenverstellvorrichtung for adjusting an effective connecting rod length of the connecting rod and a Hydraulikmediumzuleitung for hydraulic supply of hydraulic medium to Längenverstellvorrichtung, the Längenverstellvorrichtung at least one first hydraulic cylinder, at least one Piston and a first hydraulic working space and a second hydraulic working space has.

Furthermore, the present invention relates to a reciprocating engine, in particular a reciprocating internal combustion engine with at least one length-adjustable connecting rod and a vehicle with a reciprocating piston engine, in particular with a reciprocating internal combustion engine.

As a connecting rod in the context of the invention, the rod-like connecting element is referred to, which connects the crankshaft of the reciprocating piston engine with a reciprocating piston in a reciprocating engine. The connecting rod serves to convert a linear movement of the reciprocating piston, in particular a linear oscillating axial movement of the reciprocating piston, which is usually a power or working piston, in a circular movement of the crankshaft, or conversely, a circular movement To convert the crankshaft into a linear movement of the reciprocating piston.

As a crankshaft in the context of the invention, a shaft is understood which is adapted to implement in a reciprocating the linear oscillating movement, in particular the translational movement of one or more reciprocating piston by means of connecting rods in a rotary motion or vice versa, the rotational movement of the crankshaft in a to translate translational motion.

For connection to the reciprocating piston and the crankshaft, the connecting rod usually has at its two ends in each case a connecting rod bearing, usually in the form of a connecting rod, the connecting rod usually having a smaller connecting rod eye on the piston end and a larger connecting rod eye on the crankshaft end, based on a functional installation state of a connecting rod in a reciprocating engine. By means of a piston pin, which is mounted in the small connecting rod eye, then a piston can be connected to the piston end of the connecting rod. About the larger connecting rod eye, the connecting rod can be connected to the crankshaft, wherein in the larger connecting rod usually designed as a plain bearing connecting rod bearing is arranged, which is lubricated with hydraulic fluid, in particular with the engine oil of a reciprocating engine.

The connecting rod is usually mounted in each case rotatable about an axis of rotation about the crankshaft and the piston pin, wherein the distance between the two axes of rotation defines an effective or effective connecting rod length. By changing the effective connecting rod length, in particular by adjusting the effective connecting rod length, the compression ratio can be changed in a reciprocating engine, since the change of the effective connecting rod length causes a shift of the top dead center of the piston movement.

Length adjustable connecting rods are used in particular in reciprocating engines with variable compression ratio for adjusting the compression ratio. Changing the compression ratio by changing the effective connecting rod length is basically known from the prior art, for example from US Pat DE 10 2012 020 999 A1 or the WO 2015/055582 A2 ,

That in the DE 10 2012 020 999 A1 described length-adjustable connecting rod has an eccentric arranged in the smaller connecting rod eye, wherein for adjusting the eccentric at least partially outside of the connecting rod shaft two hydraulic cylinders are provided, which are supplied with engine oil from the reciprocating engine with hydraulic medium. To control the two hydraulic cylinders and thus for length adjustment of the connecting rod, a control device is provided with two valves, by means of which the two hydraulic cylinders can be acted upon in each case with hydraulic medium that adjusts the desired change in the connecting rod length.

From the WO 2015/055582 A2 a length-adjustable connecting rod with a hydraulic length adjusting device is known, wherein the connecting rod is divided into a first connecting rod shaft portion and a second connecting rod shaft portion, wherein the two connecting rod shaft sections along a longitudinal axis of the connecting rod relative to each other, in particular telescopically in or apart, are displaceable, and wherein one of two connecting rod sections forms a hydraulic cylinder and the other connecting rod shaft portion forms an associated hydraulic piston. To control the length adjusting a hydraulically actuated control device is provided with a perpendicular to the crankshaft axis in a longitudinal center plane of the connecting rod axially displaceable single-acting actuator piston as an actuating element. The actuating piston can in a functional use state of the connecting rod in a reciprocating engine using the voltage applied in an associated reciprocating engine Engine oil pressure against a restoring force generated by a spring are moved axially from a first setting position to a second setting position, depending on the setting position of the actuating piston one or more hydraulic inflows or outflows of the hydraulic length adjustment are enabled or disabled. About the spring stiffness of the return spring can be adjusted from which engine oil pressure displacement of the actuating piston is to be effected from the first control position to the second control position.

In such connecting rods with hydraulically assisted Längenverstellmechanismen arise during operation in a reciprocating engine, especially in a reciprocating internal combustion engine, during a power stroke high hydraulic working pressures in the hydraulic working spaces of Längenverstellvorrichtung, which make high demands on the sealing of the hydraulic working spaces of Längenverstellvorrichtung. Even small leaks, i. even a leakage of small amounts of hydraulic medium, can lead to a pressure reduction in the respective working space of the hydraulic length adjustment and thus to a compression or even an undesirable length adjustment of the connecting rod. This problem can increase, especially at high speeds.

Against this background, it is an object of the invention to provide an alternative, length-adjustable connecting rod for a reciprocating engine, in particular an improved length-adjustable connecting rod. Preferably, this should enable a precise holding of a set, effective connecting rod length and, in particular, an undesired length adjustment be avoided. Moreover, it is an object of the invention to provide an alternative reciprocating engine, in particular an improved reciprocating engine, and an alternative vehicle, in particular an improved vehicle, with a reciprocating engine.

These objects are achieved by the teachings of the independent claims. Preferred embodiments of the invention are the subject of the dependent claims and are explained in more detail below. The wording of the claims becomes part of the description.

An inventive length-adjustable connecting rod is characterized in that the connecting rod has at least one second hydraulic cylinder with a mass piston for generating an additional hydraulic pressure in the first hydraulic cylinder of the length adjustment, wherein the mass piston force is displaced by an occurring inertial force in the second hydraulic cylinder.

As a mass piston in the context of the invention, a piston is referred to, which is movable or displaceable by occurring inertia forces in the associated hydraulic cylinder, the mass forces arise as a result of inertia of the mass piston when the mass piston is accelerated, for example, during a working stroke of the connecting rod the mass piston acting accelerations, in particular by centrifugal forces. The second hydraulic cylinder with the mass piston thus acts as a kind of "centrifugal pump", even if it is not a pump in the true sense.

An "additional hydraulic pressure component" in the sense of the invention is understood to mean a hydraulic pressure component which can be superimposed on a (first) hydraulic pressure component which is basically available for length adjustment of the connecting rod, wherein the (first) hydraulic pressure component required for length adjustment is dependent, in particular, on an adjacent one Adjusting engine oil pressure in the reciprocating internal combustion engine, in particular in dependence on in the oil supply system of the reciprocating internal combustion engine engine oil pressure. On the other hand, the additional hydraulic pressure component is generated in particular as a function of mass forces occurring in the second hydraulic cylinder and depends inter alia, in particular, on the accelerations acting on the mass force piston.

By means of the second hydraulic cylinder can be generated in a simple manner, namely taking advantage of inertial forces, an additional hydraulic pressure component, in particular in the form of pressure pulses. In a suitably suitable design of the second hydraulic cylinder, in particular in a correspondingly suitable dimensioning of the second hydraulic cylinder with the mass piston arranged therein, and a correspondingly suitable, fluidkommunizierenden connection of the second hydraulic cylinder with the first hydraulic cylinder resulting from small leaks pressure losses in the first hydraulic cylinder of the length adjustment at least partially, in some cases even completely, and avoiding an undesirable change in the effective length of the connecting rod. In particular, can be very effectively avoided in this way a "pumping" or "springs" of the length adjustment.

A further advantage of the solution according to the invention, in particular of a connecting rod according to the invention, is that by exploiting the large accelerations occurring during a working stroke, no additional energy requirement is required for generating the additional hydraulic pressure component required for pressure equalization. as would require, for example, an (additional) pump.

The length adjustment device of a connecting rod according to the invention can in principle be designed in various ways and ways, for example as in the WO 2015/055582 A2 , in the WO 2016/203047 A1 , in the WO 2017/102108 A1 or the Austrian patent application A50757 / 2016 described, which is hereby expressly referenced for more details on the design and the operation of a length adjustment device advantageous for a connecting rod according to the invention and an advantageously designed for controlling the length adjustment control device.

Preferably, a connecting rod according to the invention has a first connecting rod shaft section and a second connecting rod shaft section, wherein preferably the two connecting rod shaft sections are displaceable relative to each other for adjusting an effective connecting rod length, in particular along a longitudinal axis of the connecting rod.

Particularly preferably, the two connecting rod shaft sections are telescopically displaceable for adjusting an effective connecting rod length, preferably along the longitudinal axis of the connecting rod, wherein in particular one of the two connecting rod shaft sections forms the (first) hydraulic cylinder of the length adjustment device and is fastened to the other connecting rod shaft section of the piston of the length adjustment device.

If a connecting rod according to the invention has a control device for controlling the length adjustment device, the control device is preferably designed such that in a first switching state of the control device a hydraulic medium return from the first hydraulic working space of the length adjustment device is blocked and the second working space is drained and in a second Switching state of the control device, the first working space is drained and a hydraulic fluid return is blocked from the first working space.

The required hydraulic supply is preferably via the hydraulic medium supply line, wherein the hydraulic medium supply line preferably hydraulic medium via the crankshaft-side connecting rod bearing is supplied.

The first hydraulic cylinder of the length adjustment device does not have to be a cylinder in the mathematical sense, but a hydraulic cylinder in the sense of the invention may also have a cross-section deviating from a circular shape over its axial length. It is only important that the first hydraulic cylinder and the piston of the length adjustment device are designed in such a way, in particular in such a way that the required for the length adjustment functionality is achieved.

In an advantageous embodiment of a connecting rod according to the invention, the massing piston is arranged to be movable in the axial direction in the second hydraulic cylinder, the massing piston preferably dividing the second hydraulic cylinder into at least one first hydraulic working space and a second hydraulic working space.

In a further advantageous embodiment of a connecting rod according to the invention the second hydraulic cylinder is arranged in the connecting rod, that its longitudinal axis is parallel to the longitudinal axis of the connecting rod, wherein the second hydraulic cylinder is preferably arranged in a longitudinal center plane of the connecting rod, in particular in a direction perpendicular to the crankshaft axis longitudinal center plane. However, the second hydraulic cylinder can also be arranged in a longitudinal center plane oriented parallel to the crankshaft axis. By means of such an arrangement of the second hydraulic cylinder in the connecting rod particularly high mass forces and consequently a particularly high, additional hydraulic pressure component can be generated, since especially in the upstroke and downstroke of the connecting rod, the accelerations occurring are particularly large, so that in particular during the up and high centrifugal forces act on the mass piston in the downstroke.

In a further advantageous embodiment of a connecting rod according to the invention, the second hydraulic cylinder is a double-acting or double-acting hydraulic cylinder, wherein the grounding force piston is preferably formed by a ground bolt and in particular has two equal effective areas.

The mass piston is preferably designed as a cylindrical bolt. The mass piston, however, may also have an angular or otherwise geometrically configured cross-section, the second hydraulic cylinder and the mass piston especially only for fulfilling the function according to the invention, namely the generation of an additional hydraulic pressure component by means of external forces, in particular by means of the centrifugal forces occurring during a power stroke, must be formed and the second hydraulic cylinder preferably has a corresponding to the mass force piston geometry formed.

It has proven to be advantageous if an effective surface of the mass piston preferably has a surface which is a circular area with a Diameter of 1 mm to 10 mm, preferably a circular area with a diameter of 1.5 mm to 5 mm, in particular with a diameter of 2 mm to 3 mm. The mass piston can have over its entire length in the axial direction a constant cross section, but also a variable over its length cross-section.

Preferably, the massing piston has a length of about 5 mm to about 50 mm, in particular from about 5 mm to about 40 mm, more preferably from about 10 mm to about 30 mm and particularly preferably from about 15 mm to 20 mm.

In a further advantageous embodiment of a connecting rod according to the invention, the second hydraulic cylinder is fluid-communicating with the hydraulic medium supply line connected or connectable, preferably via a check valve. This can ensure that the second hydraulic cylinder can always be adequately supplied with hydraulic medium, in particular always sufficiently filled with hydraulic medium and thus reliably an additional hydraulic pressure component can be generated. By means of the check valve between the second hydraulic cylinder and the hydraulic medium supply line, a return flow of hydraulic medium from the second hydraulic cylinder can be avoided so that a corresponding, additional hydraulic pressure component can be built up.

In a further advantageous embodiment of a connecting rod according to the invention the second hydraulic cylinder is fluid communicating with the first hydraulic working space of the length adjustment and / or the second hydraulic working space of the length adjustment connected or connectable. Depending on which hydraulic working space of the length adjusting device the second hydraulic cylinder is connected or connectable in a fluid-communicating manner, the additional hydraulic pressure component generated by means of the second hydraulic cylinder can be transmitted to the first hydraulic working space of the length adjustment device or to the second hydraulic working space of the length adjustment device and in each case an additional hydraulic pressure component into the hydraulic system respective hydraulic working space can be introduced. As a result, small pressure losses, for example, pressure losses resulting from leaks, at least partially, in some cases even completely, be compensated and avoided as a result undesirable length adjustment of the connecting rod or reduced.

In a further advantageous embodiment of a connecting rod according to the invention, the first hydraulic working space of the second hydraulic cylinder is in each case fluid-communicatingly connected or connectable to a hydraulic working space of the length adjustment device and the hydraulic medium supply line, in particular via a non-return valve, wherein preferably the second, i. the other, hydraulic working space of the second hydraulic cylinder is connected in fluid communication with a drain or can be connected, in particular via a throttle valve. In other words, that means that the first hydraulic working space of the second hydraulic cylinder is preferably simultaneously connected or connectable in fluid communication with both a hydraulic working chamber of the length adjusting device and with the hydraulic medium supply line, in particular via a check valve, and the second, other hydraulic working space of the second hydraulic cylinder drained second hydraulic cylinder, in particular via a throttle valve. The drainage of the second or other hydraulic working space of the second hydraulic cylinder is required to allow filling of the first hydraulic working space of the second hydraulic cylinder by suction of hydraulic medium with hydraulic medium, which is a prerequisite for a pressure required to generate the additional hydraulic pressure portion.

Under a drainage is understood in the context of the invention, a hydraulic fluid flow, by means of which hydraulic medium can be removed from a hydraulic working space for pressure reduction.

In a connecting rod according to the invention preferably at least one drainage is designed to dissipate hydraulic medium in a crank chamber of a reciprocating engine, in particular in the crankcase of a reciprocating internal combustion engine, based on a functional installation state of the connecting rod in a reciprocating engine.

In a further advantageous embodiment of a connecting rod according to the invention of a piston-side end of the connecting rod hydraulic working space of the second hydraulic cylinder is respectively connected in fluid communication with a hydraulic working space of Längenverstellvorrichtung and Hydraulikmediumzuleitung or connectable, in particular via a check valve, and facing a crankshaft end of the connecting rod Hydraulic working space of the second hydraulic cylinder is preferably fluid communicating connected to a drain or connectable, in particular via a throttle valve. In particular, the hydraulic working space of the second hydraulic cylinder facing the piston end of the connecting rod forms the first hydraulic working space of the second hydraulic cylinder and the hydraulic working space of the second one facing the crankshaft end of the connecting rod Hydraulic cylinder, the second hydraulic working space of the second hydraulic cylinder.

In a further advantageous embodiment of a connecting rod according to the invention, the connecting rod has a third hydraulic cylinder with a mass piston, wherein preferably the second hydraulic cylinder is fluid communicating connected to the first hydraulic working space of Längenverstellvorrichtung or connectable and preferably the third hydraulic cylinder with the second hydraulic working space of the length adjustment. In other words, in another advantageous embodiment of a connecting rod according to the invention two hydraulic cylinders, each with a mass piston, in particular each with a freely movable in the hydraulic cylinder arranged Massekraftkolben provided, each one of the two hydraulic cylinders is assigned to the first hydraulic working space of Längenverstellvorrichtung and the other hydraulic cylinder the second hydraulic working space of the length adjustment. Preferably, the third hydraulic cylinder is formed with the mass piston while the second hydraulic cylinder and connected in an analogous manner with the associated hydraulic working space of Längenverstellvorrichtung fluid communication or connectable and also in an analogous manner with the hydraulic medium supply line and the drainage.

In an alternative, but also advantageous embodiment of a connecting rod according to the invention, the second hydraulic cylinder is fluid-communicating with the first hydraulic working space of the length adjustment device and simultaneously communicating or connectable in fluid communication with the second hydraulic working space of the length adjustment device. That is, the second hydraulic cylinder is provided in this case to generate an additional hydraulic pressure component both in the first hydraulic working space of the length adjustment device and in the second hydraulic working space of the length adjustment device.

In a further advantageous embodiment of a connecting rod according to the invention, the first hydraulic working space and the second hydraulic working space of the second hydraulic cylinder are each connected in a fluid-communicating manner to a hydraulic working chamber of the length adjusting device and respectively to the hydraulic medium supply line, in particular via a non-return valve. In contrast to the previously described, advantageous embodiment of a connecting rod according to the invention, in which the second hydraulic cylinder and the third hydraulic cylinder are each connected only to a hydraulic working space of the length adjustment device, in this case no fluid-communicating connection of the second hydraulic cylinder is required for drainage, since each To be drained hydraulic working space of the second hydraulic cylinder preferably can be drained respectively via the length adjustment accordingly.

In a further advantageous embodiment of a connecting rod according to the invention, the second hydraulic cylinder is designed such that in at least one end position of the mass piston the first hydraulic working space and / or the second hydraulic working space of the second hydraulic cylinder is respectively filled with a residual volume of hydraulic medium or remains, said For this purpose, second hydraulic cylinders preferably have at least one stop, which limits a stroke of the mass power piston to a maximum allowable stroke.

In a further advantageous embodiment of a connecting rod according to the invention, a maximum allowable stroke of the mass piston is less than 5 mm, preferably less than 3 mm, in particular less than 2 mm, wherein the maximum allowable stroke of the mass piston is preferably between 0.5 mm and 1 mm. Even with very small hydraulic cylinders can be effectively compensated for low pressure losses, for example, resulting from small leaks pressure losses in the length adjustment.

The mass piston (s) or the mass force pin (s) preferably comprise steel and / or copper and / or titanium or another material of comparable density or is / are formed therefrom. Feature of the materials used are high density and high modulus of elasticity.

A reciprocating piston engine according to the invention is characterized in that it comprises at least one inventive connecting rod.

An inventive vehicle with a reciprocating engine is characterized in that it comprises a reciprocating piston engine according to the invention, in particular a reciprocating internal combustion engine according to the invention.

These and other features and advantages will become apparent from the claims and from the description also from the drawings, wherein the individual features may be implemented alone or in each case in the form of sub-combinations in an embodiment of the invention and an advantageous as well as for can represent protectable design for which protection is also claimed, if it is technically feasible.

The invention will be explained in more detail below with reference to non-limiting exemplary embodiments, which are illustrated in the figures. In it show at least partially schematically:

1 For example, a length-adjustable connecting rod with a generic, hydraulic length adjustment device from the prior art in a sectional view,

2 a detail of a first embodiment of a hydraulic system for a connecting rod according to the invention with a second hydraulic cylinder according to the invention with a mass piston,

3 a detail of a second embodiment of a hydraulic system for a connecting rod according to the invention with a second hydraulic cylinder according to the invention with a mass piston force,

4 1 a detail of a third exemplary embodiment of a hydraulic system for a connecting rod according to the invention with a second hydraulic cylinder according to the invention and a third hydraulic cylinder according to the invention, each with a mass piston,

5 a section of a fourth embodiment of a hydraulic system for a connecting rod according to the invention with an alternative, inventive second hydraulic cylinder with a mass piston, and

6 from the mass piston 5 in single part view in side view.

1 shows a better, fundamental understanding of the operation of a hydraulic length adjustment of a connecting rod according to the invention a known from the prior art connecting rod 1 with an advantageous embodiment of a suitable for a connecting rod according to the invention, hydraulic length adjustment 20 with a first hydraulic cylinder 21 , a piston 22 , a first hydraulic working space 23 and a second hydraulic working space 24 ,

The connecting rod 1 has a split connecting rod shaft with a first connecting rod shaft portion 2 and a second connecting rod shaft portion 3 , wherein at a piston-side end of the connecting rod 1 or the first connecting rod shaft section 2 for connection to a reciprocating piston of a reciprocating engine, in particular a reciprocating internal combustion engine, a smaller connecting rod eye 4 is provided and at a crankshaft end of the connecting rod 1 or of the second connecting rod shaft section 3 a larger connecting rod eye 5 for connecting the connecting rod 1 on a crankshaft of the reciprocating engine. The crankshaft is in 1 not shown; its longitudinal axis, the crankshaft axis KW, is normal to a longitudinal axis A of the connecting rod 1 or normal to the sheet of 1 , A median longitudinal plane of the connecting rod 1 runs through the longitudinal axis A of the connecting rod 1 and normal to the crankshaft axis, ie substantially parallel to or coincident with the plane of the plane of 1 ,

The first connecting rod shaft section 2 and the second connecting rod shaft portion 3 are telescopically along the longitudinal axis A of the connecting rod 1 slidable, wherein at the upper connecting rod shaft portion 2 The piston 22 the length adjustment device 20 is fixed and the lower connecting rod shaft portion 3 the hydraulic cylinder 21 the length adjustment device 20 forms, in which the piston 22 the length adjustment device 20 along the longitudinal axis A of the connecting rod 1 is slidably mounted. Depending on the position of the piston 22 the length adjustment device 20 in the first hydraulic cylinder 21 the length adjustment device 20 another effective or effective connecting rod length L is set, which is defined by the distance between the axes of rotation of the connecting rod 1 around the piston pin or around the crankshaft. Due to the maximum possible stroke of the piston 22 the length adjustment device 20 a maximum change DL of the effective or effective connecting rod length L is determined.

The piston 22 the length adjustment device 20 is here as a double-acting piston 22 formed, wherein the piston 22 the length adjustment device with the first hydraulic cylinder 21 the length adjustment device 20 a first hydraulic working space 23 and a second hydraulic working space 24 Are defined.

Of course, the Längenverstellvorrichtung a connecting rod according to the invention also deviates from the example in 1 be illustrated and formed on the basis of this explained Längenverstellvorrichtung, and for example as in the DE 10 2012 020 999 A1 be described described.

To control the length adjustment 20 has the in 1 illustrated connecting rod 1 as usual, a control device 40 on which a Hydraulikmediumzufluss from a hydraulic medium supply line 30 in the first hydraulic working space 23 as well as the second hydraulic working space 24 the length adjustment device 20 controls.

An inventive connecting rod preferably also has a control device for controlling the length adjustment device. The control device of a The connecting rod according to the invention can in principle be designed in various ways and ways. However, the control device is preferably like one in the WO 2015/055582 A2 , in the WO 2016/203047 A1 , in the WO 2017/102108 A1 or in the Austrian patent application A50757 / 2016 formed control device, wherein in the first two documents WO 2015/055582 A2 and those in the WO 2016/203047 A1 described control devices in each case depending on a voltage applied in a reciprocating engine engine oil pressure are hydraulically actuated while in the WO 2017/102108 A1 described control means by means of an additional, electromagnetically actuated, hydraulic switching valve can be actuated and in the A507575 / 2016 described control device is adapted to be actuated by means of a mechanically actuated, hydraulic switching valve.

In the 1 for a better, basic understanding of the operation of a controller suitable for a connecting rod according to the invention suitable control device 40 for controlling the length adjustment device 20 has a first valve V1 and a second valve V2, each with a arranged in a valve chamber valve body, which are each unspecified here, wherein the valve body can be pressed in each case by a restoring force against a likewise unspecified valve seat.

In this case, the first valve chamber of the first valve V1 is connected via a first hydraulic channel 25 with the first hydraulic working space 23 the length adjustment device 20 connected in fluid communication or fluid communicating and the second valve chamber of the second valve V2 via a second hydraulic channel 26 with the second hydraulic working space 24 the length adjustment device 20 ,

The valve body of the two valves V1 and V2 of the control device 40 are connected via a common, at least between a first position and a second position axially displaceable, unspecified connecting rod which is fixedly connected to an actuating piston, operatively connected to each other, wherein in the first position of the connecting rod and the actuating piston of the first valve body and in the second position of the second valve body is lifted by the connecting rod against a restoring force from the associated first and second valve seat. As a result, the respective associated hydraulic working space 23 respectively. 24 the length adjustment device 20 drained, since hydraulic medium through the respective valve V1 and V2 of the control device 40 can drain away.

In each case in the other position of the connecting rod or of the adjusting piston, the first valve body rests on the first valve seat and the second valve body on the second valve seat. As a result, a hydraulic fluid return from the associated hydraulic working space 23 respectively. 24 blocked. Depending on whether the hydraulic fluid return from the first hydraulic working space 23 the length adjustment is locked and the second hydraulic working space 24 the length adjustment device is drained or vice versa, either a short or a long effective connecting rod length L sets.

The adjusting piston of the control device 40 , which is also unspecified, it takes in response to a pressure applied to the actuator piston hydraulic medium pressure, which usually corresponds to a voltage applied in the reciprocating internal combustion engine engine oil pressure, the first control position or the second control position, wherein the hydraulic medium via the hydraulic medium supply line 30 the adjusting piston is supplied and the adjusting piston is axially displaceable in a direction counter to a restoring force. That is, the effective connecting rod length L and thus the associated compression ratio, arises at a connecting rod with a control device described above 40 as a function of a hydraulic medium pressure applied in the reciprocating piston, in particular as a function of an applied engine oil pressure.

At a low pressure level of the hydraulic pressure is not sufficient to move the actuating piston axially against the restoring force, so that the actuating piston occupies the first actuating position, whereby a first effective connecting rod length L is established. At a sufficiently high pressure level, the restoring force can be overcome, the actuating piston assumes the second actuating position and a second effective connecting rod length L adjusts itself.

Of course, the control device of a connecting rod according to the invention also deviates from the example in 1 represented and explained with reference to this control device and, for example, as in the DE 10 2012 020 999 A1 be described described.

For further detailed explanations of possible embodiments of length adjustment devices and control devices for a connecting rod according to the invention, reference is made in particular to the aforementioned WO 2015/055582 A2 , the WO 2016/203047 A1 , the WO 2017/102108 A1 as well as the already mentioned A50757 / 2016 directed.

On the one hand the pressure in the workspace 23 respectively. 24 increase, so that a better stability of the set connecting rod length L can be achieved, and on the other unwanted pressure losses or pressure reduction, which may arise for example by small leaks or the like, in each case not drained hydraulic working space 23 respectively. 24 the length adjustment device 20 at least partially compensate and thus reduce or avoid an undesirable length adjustment of the effective connecting rod length L, has a connecting rod according to the invention in addition to the first hydraulic cylinder 21 the length adjustment device 20 a second hydraulic cylinder with a displaceable therein by a mass force occurring mass force piston.

2 shows a detail of a first embodiment of a hydraulic system 100 a connecting rod according to the invention, not shown here with a generic, above-described length adjustment 20 with a first hydraulic cylinder 21 a piston displaceable therein along the longitudinal axis B of the connecting rod 22 , the two hydraulic workrooms 23 and 24 the length adjustment device, a previously described, generic control device 40 for controlling the length adjustment and with a previously described second hydraulic cylinder according to the invention 80 with a mass piston 81 ,

The first hydraulic working space 23 the length adjustment device 20 like in the case of 1 shown connecting rod for a starting from the hydraulic medium supply line 30 via the first valve V1 and the first hydraulic channel 25 be supplied with hydraulic medium and the control device 40 and the drainage 31A be drained, in which case between the first valve V1 of the control device 40 and the first hydraulic working space 23 another throttle valve 60A is provided. Furthermore, the first hydraulic working space 23 starting from the hydraulic medium supply line 30 over the hydraulic line 27 and the two check valves 70A and 70B be supplied with hydraulic medium.

The second hydraulic working space 24 the length adjustment device 20 like in the case of 1 shown connecting rod for a starting from the hydraulic medium supply line 30 via the second valve V2 and the second hydraulic channel 26 be supplied with hydraulic medium and also via the control device 40 and the drainage 31A be drained, wherein between the second valve V2 and the second hydraulic working space 24 a throttle valve 60B is provided. The second hydraulic working space 24 the length adjustment device 20 can also via another hydraulic line, namely via the hydraulic line 28 , starting from the hydraulic medium supply line 30 to be supplied with hydraulic medium, being in the hydraulic line 28 also a check valve 70C is arranged.

For the purposes of the present disclosure, a throttle valve is understood to mean either a separate component or a throttling section of a conduit.

The mass piston 81 is here as a double-acting piston 81 formed and along a longitudinal axis B of the second hydraulic cylinder 80 which runs in this case parallel to the longitudinal axis A of the connecting rod, freely movable, in particular axially displaceable, within the second hydraulic cylinder 80 arranged. By the arrangement of the second hydraulic cylinder 80 with its longitudinal axis B parallel to the longitudinal axis A of the connecting rod, the accelerations occurring during a working stroke, which are greatest in the longitudinal direction of the connecting rod, can be optimally utilized. The second hydraulic cylinder 80 can also be arranged differently oriented in the connecting rod, wherein the second hydraulic cylinder 80 Preferably oriented in the connecting rod is arranged such that the highest possible accelerations on the associated mass piston force 81 act to generate the largest possible additional hydraulic pressure component.

The mass piston 81 divides the second hydraulic cylinder 80 in a first hydraulic working space 82 of the second hydraulic cylinder 80 and a second hydraulic working space 83 of the second hydraulic cylinder 80 , where the first hydraulic working space 82 of the second hydraulic cylinder 80 over the check valve 70A fluid communicating with a hydraulic medium supply line 30 and over the check valve 70B and the hydraulic line 27 with the first hydraulic working space 23 the hydraulic length adjustment 20 the connecting rod according to the invention is connected.

The second hydraulic working space 83 of the second hydraulic cylinder 80 is via a throttle valve 60C fluid communicating with a drainage 31B connected by means of which hydraulic medium from the second hydraulic working space 83 can be dissipated in a crankshaft space for pressure reduction.

The occurring during a power stroke in the operation of a reciprocating engine, in particular during operation of a reciprocating internal combustion engine and on the mass piston 81 acting accelerations and the resulting centrifugal forces cause the mass piston 81 , which in this case by a small steel bolt 81 is formed in an upward stroke of the Pleuels invention due to its inertia in the second hydraulic cylinder 80 moved down, creating in the first working space 82 the second hydraulic cylinder creates a negative pressure and hydraulic medium via the hydraulic medium supply line 30 through the check valve 70A through into the first hydraulic working space 82 of the second hydraulic cylinder 80 is sucked while from the second hydraulic working space 83 of the second hydraulic cylinder 80 Hydraulic fluid via the throttle valve 60C into the drainage 31B is dissipated.

In the subsequent downward stroke, the mass piston moves 81 due to the forces acting and its inertia upwards, which makes the first in the hydraulic working space 82 of the second hydraulic cylinder 80 sucked hydraulic medium via the hydraulic line 27 ( 2 ) and the check valve 70B in the second hydraulic cylinder 80 fluid communicating connected, first hydraulic working space 23 the length adjustment device 20 is pressed. This adds an additional hydraulic pressure to the first hydraulic working space 23 the length adjustment device 20 applied, in particular a pressure pulse, which increases the pressure in the working space 23 leads, and by means of which a small, for example, caused by a leakage pressure reduction, at least partially compensated or compensated and an undesirable change in the effective Pleuellänge can be reduced or even completely avoided. In particular, can in this way very effectively a "pumping" or "springs" of the connecting rod, in particular a compression or rebound of the first, upper Pleuelschaftabschnittes 2 , be avoided.

In order to achieve an increase in pressure, which can compensate for pressure losses occurring, even small geometric dimensions are sufficient for the second hydraulic cylinder and the mass piston 81 , Already with a mass force bolt 81 , whose active surfaces only have a diameter of about 2 mm, good results can already be achieved. With an exemplary width of the connecting rod of about 25 mm - here by width or conrod width, the extension in a direction parallel to the crankshaft is understood - this means that the diameter of the active surfaces in the range of about five to 15 Percent, conveniently ten percent of the connecting rod width. Thus, a good effect is achieved while the space required by the weakening of the connecting rod is minimized.

Alternatively to the in 2 shown section of the hydraulic system 100 for a connecting rod according to the invention can in a connecting rod according to the invention, the second hydraulic cylinder 80 instead of the first hydraulic workspace 23 the hydraulic length adjustment 20 also with the second hydraulic working space 24 the hydraulic length adjustment 20 be communicatively connected or connectable, such as 3 on the section of the hydraulic system 200 exemplifies. Except for the difference 2 in that the second hydraulic cylinder 80 in the hydraulic system 200 with the second hydraulic working space 24 the hydraulic length adjustment 20 connected in a fluid-communicating manner corresponds to the hydraulic system 200 out 3 basically the hydraulic system 100 out 2 ,

Via a check valve 70C can hydraulic fluid in the first hydraulic working space 82 of the second hydraulic cylinder 80 be sucked and over the hydraulic line 28 and a check valve 70D the second hydraulic working space 24 the length adjustment device are supplied, wherein the second hydraulic working space 83 of the second hydraulic cylinder 80 via a throttle valve 60D with a drainage 31C connected is. In the hydraulic line 27 between the hydraulic medium supply line 30 and the first hydraulic working space 23 In this case, only the check valve is located 70A ,

4 shows a further embodiment of a section of a hydraulic system 300 for a connecting rod according to the invention, in which case in addition to the second hydraulic cylinder 80 with the mass piston 81 a third hydraulic cylinder 90 with a mass piston 91 is provided. Here is the second hydraulic cylinder 80 with the first hydraulic working space 23 the length adjustment device 20 fluid communicating connected and the third hydraulic cylinder 90 with the second hydraulic working space 24 the length adjustment device 20 ,

The third hydraulic cylinder 90 is analogous to the second hydraulic cylinder 80 trained and also has a first hydraulic working space 92 and a second hydraulic working space 93 on, being the first hydraulic working space 92 of the third hydraulic cylinder 90 via a check valve 70C fluid communicating with the hydraulic medium supply line 30 and over the check valve 70D with a hydraulic working space of the length adjustment device 20 , in this case with the second hydraulic working space 24 , is connected in fluid communication while the second hydraulic working space 93 of the third hydraulic cylinder 90 also via a throttle valve 60D fluid communicating with a drainage 31C connected is.

The second hydraulic cylinder 80 is like the one before 2 described, second hydraulic cylinder 80 trained and about that check valve 70A on the one hand with the hydraulic medium supply line 30 and over the check valve 70B on the other hand with the first hydraulic working space 23 the length adjustment device 20 fluid communicating connected, wherein the second hydraulic working space 83 of the second hydraulic cylinder 80 also via the throttle valve 60C with the drainage 31B connected is.

Using an in 4 illustrated hydraulic system 300 in each case by utilizing the centrifugal force in each case an additional hydraulic pressure component to the first hydraulic working space 23 the length adjustment device 20 and the second hydraulic working space 24 the length adjustment device 20 be generated, so that in particular by leaks resulting pressure losses or the like at least partially, preferably completely, in both hydraulic working spaces 23 . 24 the length adjustment device 20 can be compensated and an undesirable length adjustment of the effective or effective connecting rod length L can be reduced or even avoided altogether.

5 shows a section of a fourth embodiment of a hydraulic system 400 for a connecting rod according to the invention with an alternatively formed, second hydraulic cylinder according to the invention 80 ' with an alternately formed mass piston 81 ' , In this case, the second hydraulic cylinder 80 ' designed for both the first hydraulic working space 23 the length adjustment device 20 to generate and apply an additional hydraulic pressure component as well as for the second hydraulic working space 24 the length adjustment device 20 ,

The second hydraulic cylinder 80 ' also has a first hydraulic working space 82 ' and a second hydraulic working space 83 ' on, which each have a check valve 70A respectively. 70C fluid communicating with the hydraulic medium supply line 30 are connected for sucking hydraulic medium. The two hydraulic workrooms 82 ' and 83 ' of the second hydraulic cylinder 80 ' are also each via a check valve 70B respectively. 70D fluid communicating respectively with the hydraulic working space 23 respectively. 24 the hydraulic length adjustment 20 for applying an additional hydraulic pressure component to the respective hydraulic working space 23 respectively. 24 the length adjustment device 20 connected.

In this case, however, none of the hydraulic work spaces 82 ' respectively. 83 ' of the second hydraulic cylinder 80 ' connected to a drainage - this is not required. The respective pressure reduction or, respectively, the drainage takes place via the associated hydraulic working space 23 respectively. 24 the length adjustment device 20 , which respectively communicates with the drainage fluid accordingly 31A connectable or then connected.

To create a vacuum situation in one of the two hydraulic working spaces 82 ' respectively. 83 ' of the second hydraulic cylinder 80 ' to avoid are in this second hydraulic cylinder 80 ' in addition, compared to the above-described second hydraulic cylinders 80 or the third hydraulic cylinder 90 , two attacks 84 provided by which it can be ensured that in each case in the end positions of the mass piston 81 ' a residual volume of hydraulic medium in the hydraulic work spaces 82 ' and 83 ' remains, with the stops 84 in particular in each case one stroke of the mass piston 81 ' limit to a maximum allowable stroke. The maximum allowable stroke of the mass piston 81 is in the illustrated embodiment between 0.5 mm and 1 mm, in particular about 0.8 mm. The attacks 84 are at in a direction along the longitudinal axis B opposite end portions of the hydraulic cylinder 80 ' arranged.

The mass piston 81 ' of the hydraulic cylinder 80 ' is also of small size and preferably solid and made of steel, wherein a first diameter d1 in the region of the ends of the mass plunger 81 ' is made smaller than a second diameter d2 in the middle, over a length l1 between the ends extending portion (see. 6 ). By way of example, the first diameter d1 in the illustrated embodiment is 2 mm and the second diameter d2 of the middle section is 8 mm. In this case, the middle section of the mass piston extends 81 ' , in which the diameter is 8 mm, over a length l1 of 25 mm, while the total length l2 of the mass piston 81 ' 35 mm. The hydraulic cylinder 80 ' is designed so that the running at along the longitudinal axis B opposite portions have a diameter corresponding to the first diameter d1 and the diameter of the intermediate region whose length (in the direction of the longitudinal axis B) corresponds to the maximum allowable stroke, one to the second diameter d2 has corresponding diameter. Corresponding diameter here means that the diameters are designed with a slightly larger fit, so that the mass piston 81 ' in the hydraulic cylinder 80 ' agile, but nevertheless guided.

LIST OF REFERENCE NUMBERS

1

adjustable length connecting rod with a hydraulic length adjustment the state of the art

100, 200, 300, 400

 Section of a hydraulic system for a connecting rod according to the invention

2

 first connecting rod section

3

 second connecting rod shaft section

4

 small connecting rod eye

5

 big connecting rod eye

20

 hydraulic length adjustment device

21

 first hydraulic cylinder

22

 piston

23

 first hydraulic working space of the length adjustment device

24

 second hydraulic working space of the length adjustment device

25

 first hydraulic channel

26

 second hydraulic channel

27

 Hydraulic line to the first hydraulic working space of the length adjustment device

28

 Hydraulic line to the second hydraulic working space of the length adjustment

30

 Hydraulic fluid supply line

31A to C

 drainage

40

 control device

60A to D

 throttle

70A to D

 check valve

80, 80 '

 second hydraulic cylinder

90

 third hydraulic cylinder

81, 81 ', 91

 Inertia bolt

82, 82 ', 92

 first hydraulic working space of the second hydraulic cylinder

83, 83 ', 93

 second hydraulic working space of the second hydraulic cylinder

84

 attack

A

 Longitudinal axis of the connecting rod

B

 Longitudinal axis of the second hydraulic cylinder

d1

 Diameter of the mass piston in a first section

d2

 Diameter of the mass piston in a second section

l1

 Length of the middle section of the mass piston

l2

 Total length of the mass piston

L

 effective connecting rod length

DL

 maximum change of the effective connecting rod length

DL2

 Hub of the ground bolt

V1

 first valve of the control device

V2

 second valve of the control device

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012020999 A1 [0007, 0008, 0056, 0065]
• WO 2015/055582 A2 [0007, 0009, 0018, 0058, 0058, 0066]
• WO 2016/203047 A1 [0018, 0058, 0058, 0066]
• WO 2017/102108 A1 [0018, 0058, 0058, 0066]
• AT 50757/2016 A [0018, 0058, 0066]
• AT 507575/2016 A [0058]

Claims (14)

Length-adjustable connecting rod for a reciprocating piston engine, in particular for a reciprocating internal combustion engine, wherein the connecting rod is a hydraulic Längenverstellvorrichtung ( 20 ) for adjusting an effective connecting rod length (L) of the connecting rod and a hydraulic medium supply line ( 30 ) for the hydraulic supply of hydraulic medium to the length adjustment device ( 20 ), wherein the length adjustment device ( 20 ) at least one first hydraulic cylinder ( 21 ), at least one piston ( 22 ) and a first hydraulic working space ( 23 ) and a second hydraulic working space ( 24 ), characterized in that the connecting rod at least one second hydraulic cylinder ( 80 . 80 ' ) with a mass piston ( 81 . 81 ' ) for generating an additional hydraulic pressure component in the first hydraulic cylinder ( 21 ) of the length adjustment device ( 20 ), wherein the mass piston ( 81 . 81 ' ) by an occurring mass force in the second hydraulic cylinder ( 80 . 80 ' ) is displaceable. Connecting rod according to claim 1, characterized in that the mass power piston ( 80 . 80 ' ) movable in the axial direction in the second hydraulic cylinder ( 80 . 80 ' ), wherein the mass piston ( 81 . 81 ' ) the second hydraulic cylinder ( 80 . 80 ' ) preferably in at least one first hydraulic working space ( 82 . 82 ' ) and a second hydraulic working space ( 83 . 83 ' ) Splits. Connecting rod according to claim 1 or 2, characterized in that the second hydraulic cylinder ( 80 . 80 ' ) is arranged in the connecting rod such that its longitudinal axis (B) extends parallel to the longitudinal axis (A) of the connecting rod, wherein the second hydraulic cylinder ( 80 . 80 ' ) is preferably arranged in a longitudinal center plane of the connecting rod. Connecting rod according to one of the preceding claims, characterized in that the second hydraulic cylinder ( 80 . 80 ' ) a double-acting hydraulic cylinder ( 80 . 80 ' ), the mass piston ( 81 . 81 ' ) preferably by a ground bolt ( 81 . 81 ' ) is formed and in particular has two equal effective areas. Connecting rod according to one of the preceding claims, characterized in that the second hydraulic cylinder fluid-communicating ( 80 . 80 ' ) with the hydraulic medium supply line ( 30 ) is connected or connectable, preferably via a check valve ( 70A . 70C ). Connecting rod according to one of the preceding claims, characterized in that the second hydraulic cylinder ( 80 . 80 ' ) in fluid communication with the first hydraulic working space ( 23 ) of the length adjustment device ( 20 ) and / or the second hydraulic working space ( 24 ) of the length adjustment device ( 20 ) is connected or connectable. Connecting rod according to Claim 6, characterized in that the hydraulic working space facing a piston end of the connecting rod ( 82 . 82 ' ) of the second hydraulic cylinder ( 80 . 80 ' ) each with a hydraulic working space ( 23 . 24 ) of the length adjustment device ( 20 ) and the hydraulic medium supply line ( 30 ) is connected in a fluid-communicating manner or can be connected, in particular via a non-return valve ( 70B . 70D ; 70A . 70C ), wherein preferably one of the crankshaft-side end of the connecting rod facing hydraulic working space ( 83 . 83 ' ) of the second hydraulic cylinder ( 80 . 80 ' ) with a drainage ( 31B . 31C ) is connected in a fluid-communicating manner or can be connected, in particular via a throttle valve ( 60C . 60D ), wherein in particular the piston-side end of the connecting rod facing hydraulic working space ( 82 . 82 ' ) of the second hydraulic cylinder ( 80 . 80 ' ) the first hydraulic working space ( 82 . 82 ' ) of the second hydraulic cylinder ( 80 . 80 ' ) and the crankshaft end of the connecting rod facing hydraulic working space ( 83 . 83 ' ) of the second hydraulic cylinder ( 80 . 80 ' ) the second hydraulic working space ( 83 . 83 ' ) of the second hydraulic cylinder ( 80 . 80 ' ). Connecting rod according to one of the preceding claims, in particular according to claim 6, characterized in that the connecting rod a third hydraulic cylinder ( 90 ) with a mass piston ( 91 ), wherein preferably the second hydraulic cylinder ( 80 ) in fluid communication with the first hydraulic working space ( 23 ) of the length adjustment device ( 20 ) is connected or connectable, and preferably the third hydraulic cylinder ( 90 ) with the second hydraulic working space ( 24 ) of the length adjustment device ( 20 ). Connecting rod according to one of claims 6 to 8, characterized in that the first hydraulic working space ( 82 ) and the second hydraulic working space ( 83 ) of the second hydraulic cylinder ( 80 . 80 ' ) each with a hydraulic working space ( 23 . 24 ) of the length adjustment device ( 20 ) and in each case with the hydraulic medium supply line ( 30 ) are connected in a fluid-communicating manner or can be connected, in particular via a non-return valve ( 70B . 70D ; 70A . 70C ). Connecting rod according to one of the preceding claims, characterized in that the second hydraulic cylinder ( 80 . 80 ' ) is designed such that in at least one end position of the mass piston ( 81 . 81 ' ) the first hydraulic working space ( 82 ) and / or the second hydraulic working space ( 83 ) of the second hydraulic cylinder ( 80 . 80 ' ) is filled with a residual volume of hydraulic medium, wherein the second hydraulic cylinder ( 80 . 80 ' ) preferably at least one stop ( 84 ) having a stroke of the mass piston ( 81 . 81 ' ) is limited to a maximum allowable stroke (DL2). Connecting rod according to one of the preceding claims, characterized in that a maximum allowable stroke (DL2) of the mass piston ( 81 . 81 ' ) is less than 5 mm, preferably less than 3 mm, in particular less than 2 mm. Connecting rod according to one of claims 1 to 11, characterized in that the maximum allowable stroke (DL2) of the mass piston ( 81 . 81 ' ) is between 0.5 mm and 1 mm. Reciprocating piston engine, in particular reciprocating internal combustion engine, with at least one connecting rod, characterized in that the connecting rod is designed according to at least one of claims 1 to 12. Vehicle with a reciprocating engine, in particular with a reciprocating internal combustion engine, characterized in that the reciprocating engine, in particular the reciprocating internal combustion engine, is designed according to claim 13.

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