AT521677B1 - Assembly method for joining the telescopic rod part of a VCR connecting rod - Google Patents

Abstract

The invention relates to an assembly method for joining a telescopic rod part (18) of a length-adjustable connecting rod, comprising the following steps: providing a first section (19) of the telescopic rod part (18) comprising a connecting rod eye (9.1), the first section (19) having a connecting thread (24), providing a second section (20) of the telescopic rod part (18) comprising the piston rod (21) with a firmly connected piston (22), the second section (20) having a connecting thread (27) and the piston (22) the side facing away from the connecting thread (27) has a shoulder (29) for applying a sealing element and / or supporting element, sealing and / or supporting and / or closing elements to be attached to the piston rod at least on the second section (20) (21), or the piston (22) from the side of the associated connecting thread (24) are to be assembled, already on the second one n section (20) are arranged, providing a tool for applying a sufficiently high frictional connection to the piston rod (21) or the piston (22) by means of positive locking, applying a sufficient frictional connection by means of the tool to the second section (20) of the telescopic rod part (18), screwing the first section (19) of the telescopic rod part (18) to the second section (20) of the telescopic rod part (18) by means of the corresponding connecting threads (24, 27), applying the required tightening torque between the first section (19 ) of the telescopic rod part (18) and that on the second section (20) of the telescopic rod part (18) by means of the attached tool, a collet being provided as the tool and the front shoulder (29) of the piston (22) in a front clamping opening ( 34) a collet sleeve (33) is inserted and the application of the frictional engagement on the shoulder (29) by means of the collet over the collet sleeve (33). The invention further relates to the use of a telescopic rod part (18) of a VCR connecting rod in such a method.

Description

ASSEMBLY METHOD FOR JOINING THE TELESCOPICABLE BAR PART OF A VCR CONNECTING ROD The present invention relates to an assembly method for joining a telescopic rod part of a length-adjustable connecting rod.

The thermal efficiency η of gasoline engines is dependent on the compression ratio ε, ie the ratio of the total volume before compression to the compression volume (ε = (stroke volume V _h + compression volume V _c ) / compression volume V _c ). The thermal efficiency increases as the compression ratio increases. The increase in thermal efficiency over the compression ratio is degressive, but is still relatively pronounced in the range of today's values (ε = 10 ... 14).

In practice, the compression ratio cannot be increased arbitrarily. For example, too high a compression ratio in gasoline engines leads to knocking. The mixture ignites due to the pressure and temperature increase during compression and not due to the ignition spark. This premature combustion not only leads to uneven running, but can also cause component damage.

The compression ratio from which knocking occurs is i.a. depending on the operating point (n, T, throttle valve position) of the engine. A higher compression is possible in the partial load range. Therefore, there is an effort to adapt the compression ratio to the respective operating point. There are various development approaches for this. In the present case, the compression ratio should be adjusted by the connecting rod length. The connecting rod length influences the compression volume. The stroke volume is determined by the position of the crankshaft journal and the cylinder bore. A short connecting rod therefore leads to a lower compression ratio than a long connecting rod with otherwise the same geometrical dimensions (crankshaft, cylinder head, valve control, etc.).

In the present case, the connecting rod length is to be varied hydraulically between two positions. The mode of operation is briefly explained below. The entire connecting rod is made up of several parts, with the length being changed by a telescopic mechanism. The connecting rod contains a double-acting hydraulic cylinder. The small connecting rod eye (piston pin) is connected to a piston rod. The piston is guided axially displaceably in a cylinder which is arranged in the connecting rod part with the large connecting rod eye (crankshaft journal). The piston separates the cylinder into two chambers (upper and lower pressure chamber). The two chambers are supplied with a hydraulic medium, in particular engine oil, via check valves. If the connecting rod is in the long position, there is no oil in the upper pressure chamber. The lower pressure chamber, however, is completely filled with oil. During operation, the connecting rod is subjected to alternating tensile and compressive loads due to the gas and mass forces. In the long position, a tensile force is absorbed by the mechanical contact with an upper stop of the piston. This does not change the connecting rod length. An acting pressure force is transferred to the oil-filled lower chamber via the piston surface. As the check valve in this chamber prevents oil return, the oil pressure rises. The connecting rod length does not change. The connecting rod is hydraulically locked in this direction.

In the short position, the situation is reversed. The lower chamber is empty, the upper one is filled with oil. A tensile force causes an increase in pressure in the upper 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 chambers. Here, one of the two inlet check valves is bridged by an assigned return channel. Oil can flow through this return channel, regardless of the pressure difference between the pressure chamber and the supply part. The respective check valve loses its effect.

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AT 521 677 B1 2020-04-15 Austrian Patent Office [0008] The two return channels are opened or closed by a control valve, with exactly one return channel always being open and the other being closed. The actuator for switching the two return channels is controlled hydraulically by the supply pressure. The oil supply is provided by the lubrication of the connecting rod bearing. This requires an oil feed-through from the crankshaft journal via the connecting rod bearing to the connecting rod.

The circuit is carried out by deliberately emptying one of the two pressure chambers using the mass and gas forces acting on the connecting rod, the other pressure chamber being supplied with oil and hydraulically blocked by an inlet check valve.

A telescopic connecting rod for adjusting the compression ratio in the internal combustion engine is e.g. known from DE 10 2017 217 474 A1. In this known construction, a sleeve-shaped piston rod is formed on the small connecting rod eye, to which a hydraulic cylinder is fastened by means of a clamping screw. The piston rod is guided and sealed through a sealing sleeve that delimits the pressure chamber in the lower connecting rod part. Sealing is done like a rod seal like a hydraulic cylinder. The entire construction of the connecting rod requires that the sealing sleeve is pushed onto the piston rod before the hydraulic cylinder and the clamping screw are attached to the small connecting rod eye. The clamping screw must be tightened with sufficient torque so that the screw connection withstands the high dynamic loads during operation so that no twisting forces act on the small connecting rod eye in later operation. Such built, telescopic connecting rod parts of a VCR connecting rod are critical devices that have to withstand very high loads both with regard to the power transmission and with regard to the hydraulic conditions and are nevertheless subject to the high cost pressure in the automotive sector. There is therefore a desire to provide a simplified assembly process.

DE 10 2017 217 492 A1 describes a three-part connecting rod with an adjustable connecting rod length, a first connecting rod part having a connecting rod eye, a second connecting rod part having a double-acting piston element and a third connecting rod part having a guide cylinder for receiving the piston element and a connecting rod eye .

It is therefore the object of the present invention to achieve a simple construction of the telescopic rod part of a length-adjustable connecting rod by means of an improved assembly method.

The above. In the present case, the object is achieved by an assembly method for guiding the telescopic rod part of a VCR connecting rod with the following steps:

Providing a first section of the telescopic rod part comprising a connecting rod eye, the first section having a connecting thread, providing a second section of the telescopic rod part comprising a piston rod with a fixedly connected piston, the second section having a connecting thread and the piston on that of the connecting thread opposite side has a shoulder for applying a sealing element and / or support element, at least the sealing and / or support and / or closure elements to be fastened to the second section of the telescopic rod part, which on the piston rod or the piston from the side of the associated connecting threads are to be assembled here, are already arranged on the second section of the telescopic rod part, provide a tool for applying a sufficiently high frictional connection to the piston rod or the piston by means of a positive fit against clamping, • applying a sufficient frictional connection by means of the tool to the second section of the telescopic rod part, • screwing the first section of the telescopic rod part to the second section of the telescopic rod part by means of the corresponding connecting thread,

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AT 521 677 B1 2020-04-15 Austrian patent office • Apply the required tightening torque between the first section of the telescopic rod part and the second section of the telescopic rod part by means of the clamped tool, whereby a collet is provided as a tool and the front shoulder of the piston into one front clamping opening of a collet sleeve is introduced and the frictional engagement is applied to the shoulder by means of the collet over the collet sleeve.

First of all, it should be noted that the telescopic rod part of the VCR connecting rod has a different structure than in DE 10 2017 217 474 A1. This is because the telescopic piston rod, which in the assembled state in the lower rod part of the telescopic connecting rod for varying a compression ratio of an internal combustion engine ("variable compression ratio" - the connecting rod is therefore also referred to below as "VCR connecting rod") is sealingly guided with the Piston and not a unit with the connecting rod eye. Due to the fact that in this concept the piston always has a larger diameter than the piston rod, all additional components that are to be arranged between the connecting rod eye and the largest diameter of the piston must at least be preassembled from the thread side. This affects e.g. B. a sealing device closing the cylinder space in the lower connecting rod part, which can also be designed for guiding and sealing the piston rod. However, this can also be at least the upper piston sealing ring and a possible support device for the seal. For this reason, the division between the connecting rod eye and the piston is required. In the present case, the division takes place as close as possible to the connecting rod eye and preferably in a section which, in the switch positions of the VCR connecting rod, lies outside the lower rod part of the VCR connecting rod. So that there are no asymmetries on the piston rod and the piston, by z. b. arranged key surfaces for applying a tightening torque, the present invention provides that a tool is provided which is connected to the piston rod or the piston by means of frictional engagement and positive locking. The frictional engagement is of course so great that the appropriate tightening torque can be applied. Due to the compact design of the telescopic rod part, there are almost exclusively functional surfaces that should not be affected by this process, which is why there is a positive locking. A precise adaptation to the contour to be clamped (in particular in the longitudinal direction) is possible. There is therefore no need to provide additional sections for attaching the tool (e.g. wrench flats, hexagon socket, etc.). The construction of the telescopic rod part also has the advantage that the piston rod and the piston can be made in one piece and are therefore very robust and compact, which is why a failure of this unit is not to be expected. The counter torque is applied to the connecting rod eye, either through the connecting rod eye itself or through key surfaces attached to the connecting rod eye.

By providing the paragraph for applying a sealing element and / or support element, the corresponding force is applied to the front end of the second section of the telescopic rod part, preferably on a cylindrical paragraph, which is used for mounting further elements. It is therefore not the actual guide section of the piston, so that the requirements for a damage-free friction connection can be lower. In particular, if a support element for the front piston seal is applied to this shoulder, these requirements are the least.

The provision of a collet as a tool and the application of the frictional engagement on the heel by means of the collet have two advantages. First, the step of the heel can be used as a stop for insertion into the collet, which is why a precisely defined clamping position is specified. On the other hand, a precisely defined frictional connection can be generated with simple means using a collet. A collet is usually clamped using a clamping mechanism that is pushed over the collet sleeve. The clamping by the clamping mechanism is adjustable and lockable, so that reproducible clamping conditions can be generated. Tension

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AT 521 677 B1 2020-04-15 Austrian patent office pliers are well-known clamping devices, e.g. B. in lathes. Collets leave only slight impressions on the section to be clamped, which have little influence on the surface quality. If these have no influence on the functionality, e.g. B. if a support element for the seal is placed or pressed on, no further measures need to be taken to protect the surface.

Conveniently, it can be provided that after the application of the required tightening torque, the frictional engagement between the shoulder and the tool is released and, after the shoulder has been released, a sealing element and / or support element is mounted thereon. It is therefore the front piston seal.

In a further variant it is provided that a clamping clamp is provided as a tool, the clamping width of which corresponds at most to the available clamping width on the second section of the telescopic rod part. This makes it possible to adapt to peripheral regions of the piston rod or the piston which are also somewhat more distant from the free end. An adaptation to the contour (in particular in the longitudinal direction) of the clamping area is also possible with such a clamping clamp, in order to have little adverse influence on the surface.

It is advantageous here if, according to a variant, the clamping surface of the clamping clamp is formed from a material which is softer than the material which forms the clamping region of the second section of the telescopic rod part. As a result, the frictional engagement is applied to the second section of the telescopic rod part in an even more gentle manner.

In addition, it is also possible that the clamping region of the second section of the telescopic rod part is located on the guide section of the piston lying between a front and a rear piston seal and the clamping surface of the tool is formed from a material which is softer than that Guide portion of the piston forming material. The front piston seal does not have to be installed yet, since it can still be applied after the connection of the first section of the telescopic rod part and the second section of the telescopic rod part. The guide section of the piston is usually made very precisely and is guided in the cylinder of the second rod part of the VCR connecting rod. It is therefore important that the frictional engagement does not create any negative influences on the surface that can impair this function. The use of a correspondingly softer material helps here. The clamping surface of the tool is preferably adapted exactly to the contour of the guide section.

The tool can of course be made entirely of a softer material than the material forming the clamping area on the telescopic rod part. However, according to one embodiment, it is preferred if the tool is provided with a softer material, preferably a sufficiently strong elastomer material, in the area of its clamping surface. It is also advantageous here if this is done in an interchangeable manner, so that after certain assembly cycles an exchange can be carried out to maintain the good surface qualities on the telescopic rod part. The preferred use of an elastomer material generally also supports the application of a suitable frictional connection due to higher coefficients of friction.

In one configuration it can be provided that the guide section has a shoulder and / or a groove and the softer material acts as a compensating element for the surface contour of the guide section when the required frictional engagement is applied. For pistons that are exposed to very high pressures, as is the case with a telescopic VCR connecting rod, it may be advantageous not to design the guide section continuously, but to provide it with a drainage groove and bore so that hydraulic fluid that gets between the seal is drained away can. The softer material helps the clamping surface of the tool to line up with the contour of the piston and there is sufficient frictional engagement.

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AT 521 677 B1 2020-04-15 Austrian Patent Office [0023] Favorably, the tensioning clamp can have two clamping jaws pivotably arranged relative to one another and the pivot axis can be at a distance from the axis of the telescopic rod part that is smaller than the diameter of the clamping region of the rod part, being offset from the parting plane the clamping jaw is arranged a holder arm, the holder distance from the axis of the telescopic rod part is greater than the diameter of the clamping region of the rod part. The clamping jaws should be clamped on the telescopic rod part by means of elements which are arranged as close as possible to the clamping area. For this purpose, it is advantageous if the swivel axis is arranged as close as possible to the clamping area. Opposite the clamping axis is then z. B. a clamping screw, etc. This can also be arranged as close as possible to the clamping area, so that a uniform clamping force can be applied better. In contrast to this, the holding force or the twisting force to be applied should act as far as possible from the axis of the telescopic rod part, which is why a corresponding holding arm is offset from the parting plane of the clamping jaws. It is therefore preferably designed as a massive extension of a clamping jaw. This distance provides a correspondingly large lever arm for applying the desired force for the required tightening torque.

According to a further variant it can be provided that the tensioning clamp has a wire band loop which is adjustable in terms of its clamping circumference by means of an adjusting element and the wire band loop is positioned on the clamping area of the second section of the telescopic rod part for applying the sufficient frictional engagement. Wire ribbon loops are standard elements that are often used to attach hose elements or sleeves. The principle of action is similar to a pipe clamp. Here, an oblique slit is punched into a metal band, which is intended to represent part of an internal thread in which the thread of a screw engages. The screw is attached to the metal band by means of a special housing and is in engagement with these oblique slots. It is also possible to shape the metal strip in the manner of a rack. Such a wire ribbon loop does not necessarily have to extend over the entire clamping area, but can be attached to a suitable base so that the two ends of the wire ribbon are arranged at a distance from one another. One end can be fixed and only the other adjustable. Alternatively, both ends can be adjustably attached to the base. The respective clamping force can also be derived from the tightening torque of the screw.

In summary, the invention has the advantages that a contact pressure is generated by the firm pressing of the tool, which is so high that the frictional force between the telescopic rod part of the VCR connecting rod is sufficient to transmit the required tightening torque.

The use of key areas, e.g. B. a double flat on the first section of the rod part is not necessary, which is why the first section can be made rotationally symmetrical and therefore less expensive. There are no negative effects and alignment, as would be required with a double, is not necessary.

If a softer support material is used for the tool or for the tool itself, there are no scratches or shearings on the telescopic rod part. In the event of wear, only the pad material has to be replaced. There are no chips that could later affect the seals. The variant in which the positive clamping takes place on a shoulder on the side of the rod part facing away from the connecting thread has particular advantages. Possibly occurring wear due to the clamping only occurs on the heel, on which a support element for the seal securing is preferably pressed on afterwards. The assembly of the support element is therefore still possible without any problems. In addition, the distance between the seals on the piston can be made significantly narrower, which saves material and costs.

The invention also relates to the use of a telescopic rod part in a method with the features described above, or according to one of claims 5/18

AT 521 677 B1 2020-04-15 Austrian patent office marriage.

In the following the invention is explained in more detail by means of non-restrictive embodiments of the invention, which are shown in the drawings. Show it:

Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 shows a schematic cross section through an internal combustion engine, a variant of an assembled telescopic rod part VCR connecting rods (without front piston seal), a variant of a collet sleeve in a perspective view, a perspective view of a telescopic rod part with an attached clamp, the clamp from FIG. 4 in a plan view, a schematic cross-sectional view of a clamp with a wire loop and [0036] FIG. 7 one schematic cross-sectional representation of a variant of a tension clamp with wire ribbon loop.

is a schematic representation of an internal combustion engine (gasoline engine) 1 Darge [0037] In Fig. 1 represents. 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. The internal combustion engine 1 further comprises a crankshaft 4 which is rotatably supported by means of crankshaft bearings 5.1-5.4. The crankshaft 4 is connected by means of connecting rods 6.1, 6.2 and 6.3 with the associated reciprocating pistons 3.1, 3.2 and

3.3 connected. For each connecting rod 6.1.6.2 and 6.3, the crankshaft 4 has an eccentrically arranged crankshaft journal 7.1.7.2 and 7.3. The large connecting rod eye 8.1, 8.2 and 8.3 of the connecting rods 6.1.6.2, 6.3 is in each case on the associated crankshaft journal 7.1.7.2 and

7.3 stored. The small connecting rod eyes 9.1, 9.2 and 9.3 of the connecting rods 6.1, 6.2, 6.3 are each mounted on a piston pin 10.1, 10.2 and 10.3 and thus pivotally connected to the associated piston 3.1, 3.2 and 3.3. The terms small connecting rod eye 9.1, 9.2. and 9.3 a large connecting rod eye 8.1, 8.2 and 8.3 do not reveal an absolute or relative size assignment, but rather serve only to differentiate the components and assign them to the internal combustion engine shown in FIG. 1. Correspondingly, the dimensions of the diameters of the small connecting rod eyes 9.1, 9.2, 9.3 can be <, = or> than the dimensions of the diameters of the large connecting rod eyes 8.1, 8.2, 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 empty run of the control chain 12 is tensioned by means of a pivotably arranged tensioning rail 15, which is pressed onto it by means of a chain tensioner 16. The tension strand of the control chain 12 can slide along a guide rail. The essential mode of operation of the timing drive, including fuel injection and ignition using a spark plug, is not explained in detail and is assumed to be known. The eccentricity of the crankshaft journals 7.1, 7.2 and 7.3 essentially determines the stroke distance H _K , in particular if, as in the present case, the crankshaft 4 is arranged exactly centrally under the cylinders 2.1, 2.2 and 2.3. The piston 3.1 is shown in Fig. 1 in its lowest position while the piston 3.2 is shown in its uppermost position. In the present case, the difference gives the stroke H _K. The remaining height H _c (see cylinder 2.2) gives the remaining compression height in cylinder 2.2. In connection with the diameter of the reciprocating piston 3.1, 3.2 or 3.3 and the associated cylinder 2.1, 2.2 and 2.3 resulting from the travel path H _K the swept volume V _h and from the remaining compression height H _c is the compression volume V _c calculated. Of course, the compression volume V _c largely depends on the design of the cylinder cover. The compression ratio ε results from this volume V _h and V _c . In detail, the compression ratio ε is calculated from the sum of the stroke volume V _h and the

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Compression volume V _c divided by the compression volume V _c . Today's values for gasoline engines are between 10 and 14 for ε.

So that depending on the operating point (η, T, throttle valve position) of the internal combustion engine 1, the compression ratio ε can be adjusted, the connecting rods 6.1, 6.2 and 6.3 are designed to be adjustable in length (so-called. VCR connecting rods). As a result, a higher compression ratio can be used in the partial load range than in the full load range.

2, the telescopic rod part 18 of a connecting rod 6.1 is at least partially shown. The telescopic rod part 18 has a first section 19 with said small connecting rod eye 9.1 and a second section 20 with a piston rod 21 and a piston 22 attached to the piston rod 21. The relative movement of the telescopic rod part 18 to the second, not shown, i.e. lower connecting rod part with the large connecting rod eye 8.1, which is not shown in more detail, takes place by means of a cylinder-piston unit with the piston 22, which is arranged in a correspondingly complementary cylinder in the second connecting rod part.

The first section 19 or connecting rod head comprises in addition to the small connecting rod eye 9.1 a foot 23 which is provided with an internal thread (connecting thread 24) which is incorporated into the foot 23 from the end face 25. On the outside, the foot 23 is provided with key surfaces 26 for attaching a tool. The entire first section 19 remains outside the second connecting rod part, not shown, in the assembled state. The second section 20 comprises the piston rod 21, the external thread (connecting thread 27) arranged at the upper end of the piston rod and the piston 22 fixedly attached to the lower end of the piston rod 21. The piston 22 has a central guide section 28 and also before and after the guide section 28 arranged cylindrical shoulders 29. The piston 22 is a double-acting piston with front and rear piston surfaces, each of which cooperates with a pressure space in the cylinder of the lower connecting rod part, not shown, which is delimited by the guide surface 28 (and possibly seals). The shoulder 29 on the side of the guide section 28 facing the connecting thread 27 is covered by elements to be described in more detail. The front, shown, paragraph 29 also forms the front end of the second portion 20. Both the two paragraphs 29 and the guide portion 28 are larger in diameter than the diameter of the piston rod 21. The outer diameter of the connecting thread 27 is smaller than the outer diameter of the Piston rod 21. In the present case, the entire second section 20 (piston rod 21, cylinder 22 and connecting thread 27) is made from one piece or is inseparably connected. Therefore, all additional elements to be arranged between the first section 19 and the guide section 28 of the piston 22 must at least be preassembled before the joining of the first section 19 and the second section 20. These elements are e.g. around the piston rod seal unit 30 as well as the upper piston seal 31 and the associated support ring 32. The piston rod seal unit 30 is screwed into the lower connecting rod part during later assembly with the lower connecting rod part and therefore has a corresponding screw thread. Inside, the piston rod seal unit 30 forms the corresponding rod seals for the sealed telescopic displacement of the piston rod 21. The piston rod sealing unit 30 thus closes off the cylinder in the lower connecting rod part for the arrangement of the piston 22.

The assembly of the first section 19 and the second section 20 is explained in more detail below. The first section 19 is provided and the second section 20 is accordingly provided with the elements to be assembled, namely the piston rod seal unit 30, the piston seal 31 and the support ring 32. The connecting thread 27 of the second section 20 is then screwed into the connecting thread 24 of the first section 19 until the end face of the thread 27 strikes. Subsequently, the pre-assembled telescopic rod part 18 is clamped by means of the collet sleeve 33 shown in FIG. 3 and the remaining elements of the collet, not shown. For this purpose, the front shoulder 29 on which there is no piston seal 31 and no support ring 32

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AT 521 677 B1 2020-04-15 Austrian patent office are inserted into the front clamping opening 34 of the collet sleeve 33. The diameter of the clamping opening 34 and the outer diameter of the shoulder 29 are correspondingly adapted to one another. A sufficient clamping force is applied by means of the collet, so that there is a frictional connection between the tool formed by the collet and the peripheral surface of the front shoulder 29. The frictional engagement is so great that a torque can subsequently be applied between the first section 19 and the second section 20 by means of the key surfaces 26, so that the desired tightening torque is achieved. According to one embodiment, this can e.g. Amount to 80 Nm. The clamping by the collet sleeve 33 leaves only insignificant pressure points on the collar 29, which are common for collets. These do not affect the later assembly of the piston seal 31 and the support ring 32 as soon as the collet is removed from the shoulder 29 again. After these additional elements have been put in place, there is a fully assembled telescopic rod part 18. The tightening torque is sufficient so that it works reliably. This assembly is possible in particular because there is no key surface on the piston rod 21 or the piston 22, these are preferably configured in one piece and the cut surface between the first section 19 and the second section 20 outside the lower connecting rod part or between the piston rod seal unit 30 and the end of the connecting thread 27.

In many cases, due to the size of the piston rod seal unit 30, the available adjustment length and the size of the piston 22, the piston rod 21 is only available in exceptional cases for applying the suitable frictional engagement, which is why the frictional engagement must be applied in the region of the piston 22. But this one also has sensitive surfaces, so that only tools can be used that allow a suitable positive locking of the cylindrical surfaces.

4 and 5, a second variant of the tool and the assembly method will now be explained in more detail.

The telescopic rod part 18 is identical to the previous embodiment. The only exception is that the associated piston seal 31 and the corresponding support ring 32 are already arranged on the front shoulder 29. A special clamping clamp 35 has been provided as the clamping area, not the lateral surface of the shoulder 29, but the surface of the guide section 28 of the piston 22. So that this functional surface is not damaged when the required frictional connection is applied. The tensioning clamp has a first clamping jaw 36 and a second clamping jaw 37. The clamping jaws 36 and 37 are pivotably connected by means of a pivot axis 38. On the side opposite the pivot axis 38, both clamping jaws 36 and 37 are provided with clamping eyes 39 and 40. A clamping means can be used in the clamping eyes 39 and 40, with which a corresponding clamping force can be applied. For example, the eyelet 39 can be provided with a thread, while the eyelet 40 has only one through opening for a screw. The clamping surface of the clamping clamp 35 is provided with a layer 41 made of a softer material. This is preferably a sufficiently strong, rubber-elastic plastic in order to avoid surface damage to the piston 22. The layer 41 can be replaced when worn. The clamping surface of the clamping clamp 35 can be adapted to the contour of the piston 22, in particular the guide section 28. The guide section 28 can namely be divided into two guide surfaces with an intermediate drain groove with a leakage hole. A correspondingly flexible position 41 can compensate for this contouring of the guide section 28 as a compensating element. A holding arm 42, which is provided with a holding opening 43, is arranged on the second clamping jaw 37. A suitable holding element or element for applying a torque is inserted into the holding opening 43, which in the present case is square in cross section. So that good clamping is generated, the distance A _s between the pivot axis 38 and the axis of the guide section 28 is smaller than the diameter DF of the guide section 28. In the same way, the distance between the clamping eyes 39 and 40 is as close as possible to the axis of the guide section 28 is arranged

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The distance between the clamping eyes 39 and 40 is arranged as close as possible to the axis of the guide section 28. This produces a good clamping force because, at these distances, elastic deformations of the clamping clamp 35 do not yet have as great an effect on the clamping surface. The clamping surface is matched as precisely as possible to the cylindrical shape of the guide section 28. The width of the tensioning clamp 35 is selected so that it fits exactly between the piston seals 31 and does not damage them. So that a good holding torque can be generated, the distance A _H between the axis of the guide section 28 and the effective center of the holding opening 43 is larger than the diameter D _{f of} the guide section 28 and thus also larger than the distance A _s .

The distance A _H can preferably correspond approximately to twice the diameter D _F.

6, another embodiment of a clamp 35 will now be explained in more detail, which can also be used for the assembly method according to the invention. The tensioning clamp 35 shown in FIG. 6 has a holding arm 44, to which a wire ribbon loop 45 is attached. The structure and mode of operation of wire ribbon loops is well known. Wire ribbon loops are often used as pipe clamps. In the present case, the wire ribbon loop 45 is not completely closed, but part of the clamping area is predetermined by the inner contour of the holding arm 44. The two free ends of the wire ribbon loop 45 are each arranged in the associated lateral projection 46. Corresponding adjustment mechanisms 47 are attached in the projections 46, with which the loop width of the wire ribbon loop 45 can be adjusted. The adjustment mechanisms 47 are primarily screws whose threads engage on one side in a corresponding profiling of the wire ribbon loop 45. This profiling can be tooth elevations, similar to a helical toothed rack or corresponding slot openings in the wire band loop 45. The variant shown in FIG. 6 enables adjustment at both ends of the wire ribbon loop 45. To protect the surfaces, a pad made of a softer, more gentle material can be used between the wire ribbon loop 45 and the second section 20. The clamping can take place on the shoulder 29, the guide section 28 or on the piston rod 21.

7, a second variant of a tension clamp 35 will now be explained in more detail. This is similar to the previous exemplary embodiment, which is why the same reference numerals are used for elements which are identical and have the same structure. In the following, only the essential differences are dealt with and reference is made to the above argument.

The variant shown in FIG. 7 again uses a wire ribbon loop 45. The only difference is that it is anchored on one side in one of the projections 46 and is therefore not adjustable. The adjustment is carried out on the opposite side using the known adjustment mechanism 47.

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AT 521 677 B1 2020-04-15 Austrian patent office

REFERENCE SIGN LIST

1 Internal combustion engine 2.1.2.2, 2.3 3.2.3.2.3.3 4th cylinder Reciprocating piston crankshaft 5.1.5.2, 5.3, 5.4 6.1.6.2, 6.3 7.1.7.2, 7.3 8.1.8.2, 8.3 9.1.9.2, 9.3 10.1, 10.2, 10.3 11 Crankshaft bearing connecting rod Crankshaft journal Large connecting rod eye Small connecting rod eye Piston pin Crankshaft sprocket 12 Timing chain 13 Camshaft sprocket 14 camshaft 15 Tensioning rail 16 Chain tensioner 18th telescopic rod part 19th first section 20th second part 21 Piston rod 22 piston 23 foot 24th Connecting thread 25th Face 26 Key surface 27 Connecting thread 28 Guide section 29 paragraph 30th Piston rod seal unit 31 Piston seal 32 Support ring 33 Collet sleeve 34 Collet opening 35 Tension clamp 36 first jaw

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AT 521 677 B1 2020-04-15 Austrian patent office

second jaw

Swivel axis

Lashing eye

Lashing eye

location

Holding arm

Holding opening

Wire ribbon loop

head Start

Clamping mechanism

distance

distance

Diameter guide section

Claims (9)

1. Assembly method for joining a telescopic rod part (18) of a length-adjustable connecting rod with the following steps: Providing a first section (19) of the telescopic rod part (18) comprising a connecting rod eye (9.1), the first section (19) having a connecting thread (24), Providing a second section (20) of the telescopic rod part (18) comprising a piston rod (21) with a firmly connected piston (22), the second section (20) having a connecting thread (27) and the piston (22) on the connecting thread ( 27) facing away from a shoulder (29) for applying a sealing element and / or support element, wherein at least to the second section (20) to be attached sealing and / or support and / or closure elements which on the piston rod (21) or the piston (22) must be mounted from the side of the associated connecting thread (24), are already arranged on the second section (20) of the telescopic rod part (18), Providing a tool for applying a sufficiently high frictional connection to the piston rod (21) or the piston (22) by means of positive locking, Applying a sufficient frictional engagement by means of the tool to the second section (20) of the telescopic rod part (18) Screwing the first section (19) of the telescopic rod part (18) to the second section (20) of the telescopic rod part (18) by means of the corresponding connecting threads (24, 27), and Application of the required tightening torque between the first section (19) of the telescopic rod part (18) and that on the second section (20) of the telescopic rod part (18) by means of the attached tool, characterized in that a collet is provided as the tool and the front shoulder ( 29) of the piston (22) is introduced into a front clamping opening (34) of a collet sleeve (33) and the frictional engagement is applied to the shoulder (29) by means of the collet via the collet sleeve (33). 2. Assembly method according to claim 1, characterized in that after the application of the required tightening torque, the frictional connection between the shoulder (29) and the tool is released, and after the shoulder (29) is released, a sealing element and / or support element is mounted thereon. 3. Assembly method according to claim 1 or 2, characterized in that a clamping clamp (35) is provided as a tool, the span of which corresponds at most to the available clamping width at the second section (20) of the telescopic rod part (18), preferably at least one clamping surface the tensioning clamp (35) is formed from a material which is softer than the material forming the clamping region of the second section (20) of the telescopic rod part (18). 4. Assembly method according to one of claims 1 to 3, characterized in that the clamping region of the second section (20) of the telescopic rod part (18) on between a front and a rear piston seal (31) lying guide section (28) of the piston (22 ) and the clamping surface of the tool is formed from a material which is softer than the material forming the guide section (28) of the piston (22). 5. Assembly method according to one of claims 1 to 4, characterized in that the tool is provided in the region of its clamping surface with a softer material, preferably a sufficiently strong elastomer material. 6. Assembly method according to one of claims 3 to 5, characterized in that the guide section (28) has a shoulder and / or a groove and the softer material when applying the required frictional engagement acts as a compensating element for the surface contour of the guide section (28). 12/18 AT 521 677 B1 2020-04-15 Austrian patent office 7. Assembly method according to one of claims 3 to 6, characterized in that the tensioning clamp (35) has two pivoting jaws (36, 37), a distance (A _s ) of the pivot axis (38) to the axis of the telescopic rod part (18 ) is smaller than the diameter (D _F ) of the clamping area of the telescopic rod part (18) and offset to the parting plane of the clamping jaws (38, 37) a holding arm (42) is arranged, the holder distance (A _H ) to the axis of the telescopic rod part (18 ) is larger than the diameter (D _F ) of the clamping area of the telescopic rod part (18). 8. Assembly method according to one of claims 3 to 6, characterized in that the tensioning clamp (35) has a wire band loop (45) which is adjustable in terms of its clamping circumference by means of an adjusting element and the wire band loop (45) on the clamping area of the second section (20 ) of the telescopic rod part (18) is positioned to apply the sufficient friction. 9. Use of a telescopic rod part (18) of a length-adjustable connecting rod in a method according to one of claims 1 to 8, characterized in that the telescopic rod part (18) has a connecting rod eye (9.1) comprising a first section with a connecting thread (24) and one the piston rod (21) with firmly connected pistons (22) comprising a second section (29) with a connecting thread (27).