EP0326606A1

EP0326606A1 - Composite crankshaft and process for manufacturing it

Info

Publication number: EP0326606A1
Application number: EP88907120A
Authority: EP
Inventors: Michael Schenk
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-08-22
Filing date: 1988-08-17
Publication date: 1989-08-09
Also published as: JPH02501156A; BR8804261A; WO1989002037A1

Abstract

Dans un vilebrequin composé, les parties individuelles sont mutuellement reliées par le soudage sous vide et à haute température des surfaces de liaison prévues au niveau de leurs points de séparation.In a compound crankshaft, the individual parts are interconnected by vacuum and high temperature welding of the connecting surfaces provided at their separation points.

Description

Composite crankshaft and process for its manufacture

The invention relates to a composite crankshaft, which has the features of the preamble of claim 1, and a method for producing such a crankshaft.

It is known (W083 / 01283) to assemble a crankshaft from individual parts instead of a one-piece design. These cast or forged parts each form a cheek on which a counterweight and a part of the two adjoining pins are molded. The division of the pins makes it possible to make them hollow, which means that considerable weight savings can be achieved. Further advantages consist in the fact that the individual parts enable more economical production, can be assembled in different numbers, can be largely finished before connecting to one another, and considerably simplify the drilling in of oil wells. It is even possible to at least partially remove the ulnate The individual parts are usually welded to one another, preferably by electron beam welding. The proposal to solder the individual parts (WO 83/01283) has so far not been possible to implement. The reason for this should be primarily to be found in the fact that the high stresses on the connection points could only be mastered with a welded joint. The known welding methods that come into question for this considerably increase the production outlay, which significantly reduces the advantages of the assembled crankshaft compared to a one-piece crankshaft.

The invention has for its object to provide a composite crankshaft that allows to take full advantage of the advantages that result from the division. This object is achieved by a crankshaft with the features of claim 1.

The inventive design of the connection between the individual parts of the crankshaft allows a strength to be achieved in the area of the connection point, which is not reduced compared to the strength of the base material. The connection points can therefore be provided wherever it is advantageous for manufacturing reasons and / or for reasons of the desired properties of the crankshaft. The solution according to the invention also makes it possible to use different materials for the individual parts. Another essential advantage of the solution according to the invention is that the manufacturing cost of a crankshaft does not depend significantly on the number of connection points, because all connections can be made in a single operation, that is to say simultaneously. Nevertheless, if necessary, it is of course possible to produce only a part of the soldered connections in a first operation and to produce the remaining soldered connections in at least one further operation with a solder having a lower melting temperature.

With the crankshaft according to the invention, therefore, it is not only possible to achieve an optimum between dimensional stability and weight, given the freely selectable position of the dividing points within wide limits, it offers considerably greater possibilities for the optimal design of the cheeks and pins than is the case when the dividing points must lie in the center of the pin. Also with regard to the manufacturing costs, the advantages resulting from the manufacture of the individual parts are not negated by their connection. In addition, in the crankshaft according to the invention, the crank pins can be inserted into the eye of the associated connecting rod before the solder connections are made, as a result of which no split connecting rod eyes are required, which leads to a further reduction in mass. For the same reason it is possible in a simple manner to arrange a bearing bush made of a ceramic material, for example oxide ceramic, between the pin and the bearing shell. Oil lubrication is then no longer necessary. In addition, the running noise of the machine is reduced.

Advantageous further developments and refinements of the invention are the subject of the dependent claims.

In order to achieve a strength at the solder joints that is at least approximately equal to the strength of the material that is connected by the solder, the solder connections are preferably designed according to claim 2. The highest strength of the soldered connection is obtained if the connection surfaces are designed in such a way that the gap which is initially present and which is required to hold the solder can decrease towards zero. A cylindrical shape, in particular a circular cylindrical shape or a flat shape that allows a butting against one another at least in a partial area, may also be suitable. Wherever there is an alternating bending stress, as is the case in particular with the pins of a crankshaft, a design of the connecting surfaces according to claims 4 and 5 is more advantageous. A curvature is also to be understood as a kink in the course of the surface line. Experiments have shown that connecting surfaces, whose surface lines have a curved, in particular a wave-like or S-like, course, can be superior to the other shapes of the connecting surfaces. The surface lines of the connecting surfaces can also strike the surface surfaces of the parts connected to one another at a right angle. However, an acute angle is preferably selected. Of course, the metal line of the connecting surfaces can have both curved and conical and / or cylindrical sections. The shapes of the connecting surfaces according to claims 4 to 6 are also advantageous because of the centering of the parts to be soldered to one another.

So that the pin parts to be soldered to one another remain in the desired position before the soldering connection is completed, they can be held in this position by means of a closely fitting bushing or the like. However, the connection surfaces can also be designed for this purpose according to claim 7. A connection is thus obtained in the. Kind of a. SchnappverschJLusses._ In order to be able to slide the parts behind one another, one can be cooled and / or heated. This provides a secure shrink connection.

By designing the connecting surfaces according to claim 8, it can also be achieved that when the solder melts, the axial component of the clamping force closes the joint between the connecting surfaces.

Snap connections according to claims 7 and 8 can also be provided between two parts and at least one connecting ring or between the pin and a tube inserted therein. If a part of a pin is formed in one piece with the associated cheek, a design of the connection according to claim 9 is particularly advantageous, an additional pin part or more additional pin parts also being used for realizing a relatively large pin length or else for a connection of pin parts that cannot be soldered to one another directly because of the material from which they are made, but only with the interposition of another material, as well as for repair purposes and for ceramic bearing bushes that provide oil mist or air lubrication or complete lubrication Allowing lubrication to be dispensed with offers significant advantages. The hollow design of the pins already leads to a substantial increase in the relationship between the design strength and the weight. Further improvements in this relationship can be achieved with the features of claims 11 and 13, that is to say with an inconsistent wall thickness adapted to the different stresses during a crank rotation and / or additional stiffening elements, which are molded-on ribs and / or inserted Stiffening elements can act. However, the section modulus of the cheek can also be optimized accordingly, with ribbed or honeycomb-shaped regions being particularly advantageous as stiffening elements.

Due to the division of the crankshaft, it will generally not be difficult to work in the bores for the oil channels, even where they should preferably be provided in order to achieve optimal lubrication conditions. If necessary, the cheeks can be divided and the oil channel or the oil channels can be incorporated into these parts before assembly. Furthermore, a hollow design of the pins enables the use of pipes as an oil channel, the design of the hollow space of the crank pin as a dirt trap, the reduction of the hollow space, for example through the use of partitions or a wire mesh in order to limit the oil supply to the residual oil quantity. which is required for a start-up, or for example design the oil channel in such a way that its shape supports the oil pumping. If the crankshaft is constructed according to claim 11, there is a direct connection between the cavities of adjacent pins. Then only the latter need to be provided with oil channels.

If two or more connecting rods are mounted on a crank pin, this can be carried out without difficulty, owing to the division of the crank shaft, in such a way that it has axially offset sections.

In many cases it will be advantageous to use cast, sintered or forged parts. The cheeks can also be, for example, finely stamped plates. Furthermore, at least the cheeks can be parts made of sheet metal, and in this case too, parts of the two adjacent pins can be molded on.

The crankshaft according to the invention enables an undivided eye of at least one connecting rod to be pushed onto the crank pin when assembling the basket shaft. Such a connecting rod has a much smaller mass than one with a split eye, which leads to further, essential advantages, including a smaller space requirement.

The invention is also based on the object of specifying a method for producing the crankshaft according to the invention. This object is achieved by a method having the features of claim 20.

Such a design of the soldered connection in connection with a design of the connection surfaces in such a way that the gap between them can go to zero leads to a strength of the connection which is not less than the strength of the base material, ie the material from which the Cheeks and cones exist. The heating is preferably carried out by induction and / or by infrared radiation. A particular advantage of the method according to the invention is that heat treatment of the parts and, if necessary, of the solder can follow immediately after the soldering process. For this purpose, only the cooling process needs to be controlled accordingly. It is therefore possible, for example, to compensate during the cooling process, which must be carried out in a separate operation in the known processes.

Also of considerable importance is the possibility of allowing gaseous, active nitrogen to act on the crankshaft during the cooling process for the purpose of the nitriding that results in hardening. Since this nitriding can take place at a much higher temperature than the usual nitriding in a bath, it takes place in a considerably shorter period of time, and it is therefore possible, for example, to achieve such strong nitriding in a period of 15 to 20 minutes that a subsequent one Finishing processing still a sufficient thick, nitrided layer remains. Of course, nitriding by means of gaseous nitrogen can also be carried out during reheating following the remuneration for the purpose of so-called tempering.

It is also advantageous that all soldered connections of the crankshaft can be made at the same time. However, the parts of the crankshaft can also be connected to one another in two or more successive soldering processes. In the subsequent soldering process, a solder with a melting temperature lower than that of the solder used in the previous soldering process must then be used.

Solder in the form of a paste or in the form of preferably bound granules is advantageous. In a preferred embodiment, however, a solder foil is inserted between the mutually assigned connecting surfaces, which is stamped or deep-drawn, for example, in order to have the desired shape. Such solder foils simplify the assembly of the crankshaft. If there is a cavity in the area of the solder joint that is only connected to the environment via the separation point, a solder foil can be used. If, in such an embodiment, the vacuum in the environment is reduced compared to the vacuum in the cavity after the solder has flowed, for example by introducing gas into the vacuum furnace, then the pressure difference causes the connecting surfaces to be pressed against one another more strongly.

If the pins are provided with oil holes, they can be used for the correct positioning of the individual parts. A pin according to claim 29 is expediently used here, the pin consisting of a material with which the solder does not bond, so that the pin can be removed again after the soldering process. An angular positioning of the individual parts is also possible with other means. For example, you can give the connecting surfaces a shape, for. B. a polygonal shape that allows joining only in the correct Winkel¬ position. Since the individual parts of the crankshaft according to the invention are small compared to a one-piece crankshaft, they can be processed very precisely before assembly. Added to this is the extremely low delay. Therefore, the crankshaft according to the invention can be manufactured according to claim 29.

The cheeks can also consist of a spacer body against which the ends of the two pins to be connected to this cheek rest and a band placed around the pin ends and the spacer body. For weight reasons, the band can consist of a material reinforced with carbon fibers or similar fibers and the spacer body can be made of ceramic. In order to be able to solder the spacer body to the pin ends with such a choice of material, the connecting surfaces must be metallized. A solder connection is preferably also provided between the band on the one hand and the spacer body and the pin ends on the other. The invention is explained in detail below on the basis of exemplary embodiments illustrated in the drawing. Show it

1 is a view of a first embodiment,

2 shows a longitudinal section of one end piece of this exemplary embodiment,

3 is a view of the end piece of FIG. 2,

4 shows a longitudinal section of a center piece of the first exemplary embodiment,

5 is a view of the center piece of FIG. 4,

6 shows an incompletely illustrated longitudinal section of part of the first exemplary embodiment,

7 is a partially sectioned, incomplete view of a second embodiment,

8 is a partially sectioned, incomplete view of a third embodiment, 9 is a partially sectioned, incomplete view of a fourth embodiment,

10 shows a section along the line X - X of FIG. 9,

11 shows a partially in section, incomplete view of a fifth embodiment,

12 shows a section along the line XII = XII of FIG. 11,

13 shows a longitudinal section of an incompletely illustrated sixth exemplary embodiment.

14 shows incompletely shown longitudinal sections of further exemplary embodiments, each showing only one solder joint to 21

22 shows a schematically illustrated longitudinal section through the crank pin and in each case a part of the two cheeks of another embodiment example carrying it.

Fig.23 is a perspective view of the

Embodiment according to FIG. 22 between the solder foil inserted between the connection surfaces.

24 shows a section corresponding to FIG. 22 of a modified exemplary embodiment. The crankshaft according to FIGS. 1 to 6 is provided for a four-cylinder reciprocating piston engine and is composed of two end pieces 1 and 2 and six middle pieces, which are precisely forged parts, but which can also be cast or sintered . All middle pieces have the same shape as a blank and can therefore be manufactured in the same tool.

On the two end pieces 1 and 2 each forming a cheek, in addition to the main bearing pin 1 'or 2', a crank pin part 4 is formed, the axial length of which is somewhat greater than half the axial length of the entire crank pin. A crank pin part 6 and a main bearing pin part 7 are formed on each middle piece, which also forms a cheek 3. The pins are provided with an outer seat or an inner seat at the division point so that they can be inserted into one another. The surfaces of these seats form the connecting surfaces that are soldered together.

As shown in FIGS. 2, 4 and 6, both the crank pin parts 4 and 6 and the main bearing pin parts 7 each have a cavity 9 which extends in the longitudinal direction thereof and which has a rounded material section 9 'of the cheeks 3 carrying the pin parts is closed. Such a cavity contributes significantly to the achievement of a very high level of design stability of the center pieces and the two end pieces 1 and 2. As a result of the relatively small mass of the crank pins, the mass of the counterweights 10 and 11 formed on the cheeks 3 is also relatively small. In the exemplary embodiment, these counterweights have the form of a ring section lying in the plane of the cheek, which is connected to the cheek by means of three arms which are formed in one piece and which extend radially.

At least one oil hole 12 penetrates the web of each middle piece 3 between the cavities 9 of the main bearing part 7 and the crank pin part 4. Furthermore, the crank pin part 4 is provided with an oil hole 13 running radially outwards from its cavity 9, but which is also offset at an angle with respect to the can be shown to improve the formation of lubricating film. The end pieces 1 and 2 are each provided with an oil channel formed by the holes 14 and 15. As indicated in FIG. 6 with a dash-dotted line, each oil bore 12 can be connected to the associated oil bore 13 by means of a pipe 16.

The parts in the area of their spigots, except for finish grinding, which are provided with the necessary oil holes, are assembled in the correct angular position, with a precisely fitting holding device holding the parts in this position. An appropriately shaped solder foil is inserted at each connection point between the two connection surfaces. Subsequently, the assembled crankshaft in a vacuum or high vacuum is heated to the required temperature door, which is about 600 ⁰ C and preferably in the Bereiph of 1000 ° C. In the subsequent controlled cooling process, the material forming the cheeks and tenons is tempered and the soldering zones are given _a high_ toughness by heat treatment. If necessary, a gaseous nitrogen is introduced into the vacuum furnace during the cooling process at a temperature above 400 ° C and the crankshaft is nitrided.

All of these methods prevent warping of the crankshaft, so that it is practically without delay after the cooling process. Therefore, a slight final grinding of the pins is sufficient, in which only a part of the ^" nitrided layer is removed.

The exemplary embodiment of a crankshaft shown in FIG. 7 differs from the exemplary embodiment according to FIGS. 1 to 6 only by a different design of the dividing points in the region of the pins. Of course, the number of main bearing journals and crank journals could also be chosen differently. It is even possible, which also applies to all other exemplary embodiments, to provide different crank pins, for example those with different strokes, in order to equip two or more reciprocating piston machines with a single crank shaft. Both the main bearing journal 108 and each existing crank journal 105 consist of two parts 107 and 107 'or 106 and 106' formed on the associated cheeks 103. The parts 106 and 107 each have an outer cone as a connecting surface, which extends from the outer surface to the inner surface concentric to the longitudinal axis of the journal. However, as shown, the outer cone does not need to form the entire outer lateral surface of the parts 106 or 107. This could also have a section with a cylindrical outer surface.

The parts 106 'and 107' each form an inner cone which is adapted to the associated outer cone, as a result of which both cone surfaces can come into contact with one another.

When assembling the short wave for the soldering process, a truncated cone-shaped solder foil made of a copper-based or nickel-based solder material is inserted between the conical surfaces assigned to one another.

A vertical arrangement of the crankshaft in the vacuum soldering furnace suffices that when the solder melts, the connecting surfaces belonging together move so far against one another that the gap which is initially present is reduced towards zero, which is due to the high temperature and the design of the soldering process in a vacuum or high vacuum leads to a diffusion bond with alloy formation, which gives a strength which is the same as that of the base material. During the cooling process following the production of the soldered connection, the base material and the soldering points are tempered and, if necessary, nitriding.

Oil bores 112 connect the cavities of the main journal and crank journal. As shown in FIG. 7, the oil bores 113 penetrating the crank pins can be offset circumferentially from the point of maximum eccentricity, which improves the oil film formation in the area of the highest load. The exemplary embodiment according to FIG. 8 differs from that according to FIG. 7 only by a different design of the connecting surfaces of the crank pin 205 and the main bearing pin 208, ie the arrangement of the oil bores of the crank pin. For the remaining details, reference is therefore made to the preceding explanations.

In the exemplary embodiment according to FIG. 8, identically designed individual parts can be used because the pin parts 206 and 207 formed on the cheeks 203 are the same. Its outer surface forming a connecting surface forms an outer cone which extends up to the cylindrical inner surface. Each ring body 217 or 218 has two inner cone surfaces and cylindrical outer surfaces which are matched to the outer cones of the crank pin parts 206 and the main bearing pin parts 207. Of course, it would also be possible to design the connecting surfaces of the pin parts as an inner cone and those of the ring body as an outer cone. It would also be possible to provide the ring body with an outer cone and an inner cone and, accordingly, to design the connecting surfaces of one pin part as an outer cone and that of the other pin part as an inner cone.

As shown in FIG. 8, the crank pin 206 is penetrated by two oil bores 213 in the radial direction. Instead of these two oil bores, however, only one can also be provided, and in addition the oil bores can be offset in the circumferential direction with respect to the point at maximum Eccentricity.

If, as shown in FIG. 8, two oil bores 213 are provided which penetrate one or the other crank pin part 206, these oil bores can be used to position the parts of the crankshaft to be connected to one another. For this purpose, one pin is advantageously used, which is inserted into each of the oil holes, carries a sleeve made of solder material, the thickness of which is equal to the difference between the diameter of the oil hole and the diameter of the pin, and the surface of which is treated in such a way that that it does not connect to the solder. The pin therefore does not prevent it from melting of the solder so close to the conical connection surfaces that the previously existing gap is practically reduced to zero.

Since the load, particularly of the crank pin, shows great differences in the individual angular positions during one revolution of the crank shaft, an even more favorable ratio between design strength and weight can be achieved if the moment of resistance of the crank pin is adapted to this different load. This adaptation can take place in various ways. FIGS. 9 and 10 show one possibility. The parts 306 and 306 ′ of the crank pin 305 formed onto the cheeks 303 are provided with an inner cone or an outer cone as a connecting surface, analogously to the exemplary embodiment according to FIG. 7. However, as shown in FIG. 10, the hollow crank pin 305 has an inner lateral surface which is arranged eccentrically with respect to its cylindrical outer lateral surface, which results in an inconsistent cross section in the circumferential direction. The largest cross section is provided in the exemplary embodiment in the third quadrant, since the highest loads on the crank pin occur here. Such a moment of resistance of the crank pin, which varies over the circumference, could also be achieved by other means. . for example molded stiffening ribs.

As in the exemplary embodiment according to FIG. 7, an oil bore 313 penetrating radially through the crank pin 305 is offset so far in the circumferential direction from the point of maximum eccentricity that an adequate lubricating film is also formed in the area of the maximum load on the crank pin 305.

As the exemplary embodiment according to FIGS. 11 and 12 shows, neither the crank pins nor the main bearing pins need to have parts molded onto the cheeks 403. Rather, the cheeks 403 can also be stamped, in particular finely stamped, plates, which are provided with cylindrical punchings for receiving the main bearing journals 408 and the crank journals 405. The pegs can then be formed by pipe sections, measures of stiffening and optimization of the section modulus being of course possible. In the exemplary embodiment according to FIGS. 11 and 12, the lateral surfaces of the punched-outs, which each form a connecting surface, are cylindrical, since the end sections of the pins engaging in the punched-out areas also have a cylindrical outer jacket surface as a connecting surface. Of course, other configurations of the connecting surfaces, for example a conical shape, would also be possible.

11 and 12 also show that the crank pin 405 can engage in the interior 409 of the main bearing pin 408 to a degree that is greater than the wall thickness of the crank pin 405 in the area of this engagement. This creates a direct connection between the cavities of the pins, which can serve as an oil channel and is therefore designated by 412 in FIG. 12. Since the pins 405 and 408 consist of tubes which are open at their ends, sealing plates 419 which are inserted in the region of the tube ends are soldered to them and can also serve as stiffeners in the manner of gusset plates at the same time. Of course, these sheets 419 can also be arranged in such a way that the space available for "taking up the oil is reduced to the desired extent. This is indicated, for example, by the sheet 419 'in FIG. 11.

The advantage of the crankshaft according to the invention to provide dividing points wherever this is advantageous opens up the possibility, as shown in FIG. 13, of designing the cheeks and the pins as shaped sheet metal parts. The cheeks 503 are each composed of a first part 503 ', to which a main bearing part 507 is integrally formed, and a second part 503'', to which a crankpin part 506 is formed. Both the first two parts 503 'and the two second parts 503''are each designed identically. Both parts form overlapping edge zones as connecting surfaces. In the exemplary embodiment, these edge zones are each formed by a generator which is parallel to the journal axis, but can also have a conical shape. The same applies to the connecting surfaces of the main journal parts 507 and the crankpin parts 506, against which the cylindrical inner circumferential surface of an annular body 517 bears, with which the journal parts are soldered. Of course, a conical shape of the connecting surfaces would also be possible here. The ring bodies receiving the main bearing journal parts 507 are not shown in FIG. 13, since they are designed in principle like the ring body 517.

A bearing bush 519 made of oxide ceramic is arranged on each ring body 517. Such bushings could also be provided in the previously described embodiments. The oil holes would then be omitted there, since such bearing bushes enable lubrication-free storage.

The eye 520 of the associated connecting rod which is mounted on the bearing bush 519 is of undivided design since it can be pushed over the connecting body 517 like the bearing bush 519 when assembling the crankshaft. Connecting rods with an undivided eye can of course also be provided in the other exemplary embodiments, since the division of the connecting rod journals here also allows them to be pushed on during assembly. However, the bearing surfaces must then be finished before the soldering.

The soldering in a vacuum and the subsequent heat treatment is carried out in the vacuum oven as described above. The temperatures occurring here are not detrimental to the ceramic bearing bushes.

In the exemplary embodiments described above, the connecting surfaces lie entirely in circular cylindrical or conical surfaces. FIG. 14 shows an embodiment in which only the central section 603 of the connection surfaces of two parts 601 and 602 of a hollow cylindrical pin, which are soldered to one another, defines a conical surface. This middle section 603 is followed by an end section 604 and 605, respectively, in which the surface lines have an arcuately curved course, where they meet the outer or inner surface area of the pin at a right angle. Instead of the right angle, an acute angle could also be provided. A particularly high strength of the solder connection, in particular a very high flexural fatigue strength, can be achieved with such curved connecting surfaces having connecting lines.

In the modification of the embodiment shown in FIG. 14 shown in FIG. 15, the surface lines of the connection surfaces of two parts 606 and 607 soldered to one another also have a curved course in the region of their two end sections 609 and 610. But they hit the outer or inner surface of the pin at an acute angle. Furthermore, the central section 608 of the connecting surfaces has a very weakly conical shape. It could also be circular cylindrical. With a conical shape, however, a gap between the two connecting surfaces can also be eliminated in the central section by loading the pin in the axial direction.

In the exemplary embodiment according to FIG. 15, as in the case of that according to FIG. 14, a solder foil adapted in shape to the connecting surfaces is inserted between the two connecting surfaces. As a result of a force acting in the axial direction of the pin, as soon as the solder flows, the connecting surfaces pressed to virtually completely clear the gap.

In the exemplary embodiments described so far, not only a force acting in the longitudinal direction of the pin, which is to be applied from the outside, is required in order to close the gap as soon as the solder begins to flow. If all soldered connections are to be made at the same time, care must also be taken to ensure that the longitudinal axes of the parts to be connected are flush with one another, that is to say that the pins at the connection points have no kinks, the cheeks are all parallel to one another and the longitudinal axes the pin is at the correct angle on the surfaces defined by the cheeks. You can achieve both goals with the help of a clamping device, which holds the individual parts in the correct position and clamps them together.

Such a costly clamping device, which takes up space in the vacuum furnace, is not required if the connecting surfaces according to FIG. 16 are formed. The connection surfaces of two parts 611 and 612 of a pin which are soldered to one another, as shown in FIG. 16, have an oppositely curved course in their two end sections 614 and 615, as is also the case in the exemplary embodiments according to FIGS. 14 and 15. However, the diameter of the connecting surface of the part 611 does not decrease continuously from the place of its greatest value to the place of its smallest value, as is the case with the exemplary embodiments according to FIGS. 14 and 15. Rather, it increases again in the area of the middle section 613. The resulting wave-shaped course of the lines of the connecting surface leads to the two end sections of the parts 611 and 612 engaging behind one another. For joining the two parts 611 and 612, it is therefore necessary to heat one part and / or to cool the other part until the two end sections can be pushed over one another. If both parts then again have the same temperature, they are not only firmly connected to each other as in a shrink connection, so that they can no longer rotate relative to each other. Alignment of the longitudinal axes is also ensured. If the two parts have a sufficiently high elasticity, the sliding over one another can also take place with the aid of a correspondingly high pressing force acting in the axial direction. The shape of the central section 613 according to the invention means that the tensioning force has a component in the axial direction which eliminates the gap which is still present when the solder flows.

As shown in FIG. 17, in the case of two parts 616 and 617, for example, only a section 618 of the two associated connecting surfaces can be formed such that the parts 616 and 617 engage behind one another and give the remaining part 619 of the connecting surfaces a conical shape .

Even if two parts, for example two parts 701 of a journal of a crankshaft, are connected to one another by an annular body, as is the case in the exemplary embodiment according to FIG. 8, instead of conical connecting surfaces, the surface lines of the connecting surfaces can have a curved or wavy course give, as shown in Fig. 18 for an inner ring 703. Since, as in the exemplary embodiments according to FIGS. 16 and 17, the course of the surface lines of the connecting surfaces of the inner ring 703 on the one hand and the two parts 701 and 702 on the other hand is selected such that the inner ring 703 both the one and the other part 701 and 702 engages behind, the clamping force also has a component in the axial direction.

Instead of letting the two pin parts butt against one another, one can of course, as shown in FIG. 19, the connecting surfaces 718 via which the parts 701 'and 702' of the pin are directly connected to one another give forms described above. In the exemplary embodiment shown, the surface lines of the connecting surfaces 718 have a slightly undulating course along a straight line which impinges on the outer surface surface at an acute angle. The inner ring 703 'is basically designed like the inner ring 703. When using a ring with a curved or wave-shaped course of the surface lines of its connecting surfaces, the ring, as shown in FIG. 0, can also be designed as an outer ring 717 analogously to the exemplary embodiment according to FIG. It can then serve as a bearing bush for at least a connecting rod ^"and selbst¬ also consist of a material other than the two parts 706 of the pin, for example of ceramic, which is metallised in the region of the connecting surfaces. The joint surfaces 704, with which the two parts 706 abut one another directly, for example have a conical shape.

Instead of designing the connecting surfaces in such a way that they engage behind like a snap lock, or in addition to such connecting surfaces, a socket 801 can be provided, as shown in FIG. 1, which bridges the connection point and between the one and the two to be connected Share a tight fit, preferably a shrink connection. In the case of a hollow pin, the parts 802 of which are provided on or connected to a cheek 803, the bushing 801 can be placed against the inner surface of the two parts 802. With a sufficient length of the socket 801, which is the case if it extends into the region of the cheeks 803, an alignment of the longitudinal axes of both parts 802 is also secured against soldering.

The connecting surfaces 804 of the parts 802 have a shape as in the exemplary embodiment according to FIG. 15. Of course, the other forms according to the invention could also be used FIG. 21 further shows that, in the exemplary embodiment by means of a sleeve 815, the pin can have a section that differs from the section lying next to it, for example with regard to its diameter. An eccentric position is more important than another diameter. Such an eccentricity can be realized, for example, if the sleeve 815 has an outer surface arranged eccentrically to its inner surface.

However, a bushing arranged inside a hollow journal of a crankshaft does not need to be in full contact with the inner jacket surface of the journal. As shown in FIG. 22, in this exemplary embodiment each of the two parts 805 of the journal of a crankshaft is provided with an annular, inwardly projecting material portion 805 'at a distance from the two parts of the joint joint, which are also formed by an inserted ring could. A bush 806 lies tightly against these two material parts 805 ', which have the same inner diameter. The socket 806, the material portions 805 'and the inner circumferential surface of the pin thus delimit a cavity 810 which, until the soldered connection is made, is only connected to the environment via the joint between the connecting surfaces 807 of the two parts 805. The connection surface 807 has a shape as shown in FIG. 15. However, other shapes, in particular shapes that result in reaching behind, are also possible. As shown in FIG. 23, the solder plate 808, which is inserted between the connection surfaces 807, is adapted to this shape of the connection surfaces. A continuous slot 809 in the solder plate ensures that de _. s solder the cavity 810 is in connection with the environment and is therefore also evacuated. However, as soon as the solder flows, the gap between them closes the connection surfaces 807 completely and closes the cavity 810. Now the vacuum acting in the environment is reduced, i.e. gas is introduced into the vacuum furnace. This creates a differential pressure between the vacuum in the cavity 810 and the surroundings of the crankshaft, from which a force results, which also compresses the parts 805 in the axial direction and therefore helps to eliminate the gap between the connecting surfaces 807.

The exemplary embodiment according to FIG. 24 differs from that according to FIG. 22 only in that the radially inwardly projecting material parts 805 'of the parts 805 of the pin carried by the cheeks 811 engage in annular grooves in the socket 806 and in that the pin has oil holes 812 is provided, which penetrate the pin wall from the cavity -810. The cross-sectional shape of the material parts 805 'and the annular grooves of the socket 806 receiving them is selected so that the clamping force with which the engagement in the annular grooves takes place also results in a force component in the axial direction. This force component has the same effect as in the exemplary embodiments according to FIGS. 16 to 20.

In order to bring the socket 806 into the installation position shown in FIG. 24, the parts 805 of the pin are heated and / or the socket 806 is cooled, namely until the socket 806 can be inserted into the pin.

An oil supply pipe 813 opens into the cavity 810, which can be inserted into the interior of the socket 806 through the opening in the cheek 811 and from here penetrates the socket 806 to the mouth into the cavity 810. In the cavity 810, the size of which can easily be adapted to the desired value, means be seen, which hold back the oil required for a start-up and feed the oil holes 812 during a start-up.

All of the features mentioned in the above description and also the features that can only be inferred from the drawing are further refinements of the invention, even if they are not particularly emphasized and are not mentioned in the claims.

Claims

P a t e n t a n s r u c h e

1. Assembled crankshaft, the individual parts of which are soldered to one another in the area of their connecting surfaces provided at the dividing points, characterized in that the soldered connections are designed as high-temperature solderings in a vacuum.

2. Crankshaft according to claim 1, characterized in that the soldered connections are diffusion connections.

3. - Crankshaft according to claim 1 or 2, characterized in that the mutually associated connecting surfaces (603-605; 608-610; 613-615; 618, 619; 704; 718; 804; 807) have a gap-free form allowing one another to have.

4. Crankshaft according to one of claims 1 to 3, characterized in that the connecting surfaces have a conical shape at least in a partial area (603; 608; 619; 704).

5. Crankshaft according to one of claims 1 to 4, characterized in that the generatrices defining the connecting surfaces have at least in a partial area (604, 605; 609, 610; 614, 615) a curved course. 6. Crankshaft according to claim 5, characterized ge ¬ indicates that the surface lines in the section having a curvature (613-615; 618) have a wavy course.

7. Crankshaft according to one of claims 1 to 6, characterized g e k e n n z e i c h n e t that of two mutually soldered connecting surfaces (613-615; 618;

619) at least one section that can be accessed by the other.

8. Crankshaft according to claim 7, characterized ge ¬ indicates that the engaging portion of the one connecting surface (613-615; 618, 619) and this portion engaging portion of the other connecting surface each have a design which before the solder connection in the the two joined parts (611, 612; 616, 617; 701, 702; 701 ', 702'; 706) results in a clamping force which, in the sense of an approximation of the two connecting surfaces (613-615; 618, 619; 718) has interacting components.

9. Crankshaft according to one of claims 1 to 8, characterized in that at least one of its pins has an annular pin part (217; 203; 203 '; 717) which has two other parts (206; 701, 702; 701', 702 ' ; 706) of the pin connects to each other via a solder connection.

10. Crankshaft according to one of claims 1 to 9, characterized in that at least one of its pins outside and / or in its interior carries a socket (801; 806), which consists of a metal or a ceramic material, in particular oxide-ceramic. 11. Crankshaft according to claim 10, characterized ¬ indicates that in an arrangement inside the hollow pin, the bushing (806) on radially inwardly projecting elements (805 ¹ ), preferably in the circumferential direction closed elements, is present.

12. Crankshaft according to claim 11, characterized ge ¬ indicates that the projecting elements (805 ') seen in the longitudinal direction of the pin are provided in front of and behind a solder joint of the pin and engage in recesses in the bushing (806), the design of which, like that of Elements is chosen so that a clamping force between the elements (805 ') and the socket (806) has a force component acting in the sense of an approximation of the connecting surfaces of the soldered connection point.

13. Crankshaft according to one of claims 1 to 12, characterized in that at least one of its hollow pins (305) has a moment of resistance which is inconsistent in different radial directions, at least in the region forming a bearing.

14. Crankshaft according to one of claims 1 to 13, characterized in that the hollow crank pin (405) protrudes on a part of its circumference to an extent into the interior (409) of at least one adjacent, also hollow main bearing pin (408) , which is greater than the wall thickness of the crank pin (405).

15. Crankshaft according to one of claims 1 to 14, characterized in that the crank pin has at least two axially offset sections arranged side by side in the axial direction. 16. Crankshaft according to one of claims 1 to 15, characterized in that the cheeks (403) are formed by finely stamped plates.

17. Crankshaft according to one of claims 1 to 15, characterized in that the cheeks (503) are parts formed from sheet metal.

18. Crankshaft according to one of claims 1 to 17, characterized in that at least one undivided eye (25) of a connecting rod is mounted on the crank pin (506, 517).

19. - Crankshaft according to one of claims 1 to 18, characterized in that the cheeks have an optimized section modulus with respect to the stress of different magnitudes during one revolution.

20. A method for producing a crankshaft according to claim 1, characterized in that at least during that period of time in a vacuum, preferably in a high vacuum, the production of high-temperature soldering, in which flows to the solder, on the individual parts of the crankshaft to be soldered to one another associated connecting surfaces in plant to bring together seeks force.

21. The method according to claim 20, characterized in that the parts to be soldered are heated inductively and / or by means of infrared radiation.

22. The method according to claim 20 or 21, characterized in that during the on Soldering process following cooling or during a subsequent reheating gaseous active nitrogen for the purpose of hardening can act on the crankshaft.

23. The method according to claim 22, characterized in that the nitriding is carried out at a temperature above 400 ° C.

24. The method according to any one of claims 20 to 22, characterized in that all the soldered connections of the crankshaft are produced simultaneously.

24. The method according to any one of claims 20 to 24, characterized in that a solder paste and / or a solder granule between the connecting surfaces to be soldered together _. ulat, preferably a solder foil, is brought.

26. The method according to claim 25, characterized in that the solder foil is punched and / or deep-drawn between the connecting surfaces before being introduced.

27. The method according to any one of claims 20 to 26, characterized in that when there is a cavity of the crankshaft which is only connected to the environment via a joint, a solder foil lying in the joint is provided with an interruption through which the cavity passes is evacuated and is designed so that the flowing solder closes the connection between the cavity and the surroundings of the crankshaft, and that after the flow of the solder, but before it has solidified again, a pressure increase in the surroundings of the crankshaft is brought about. 28. The method according to any one of claims 20 to 27, characterized in that for correct positioning of the individual parts, the parts to be connected to one another of the pin provided with at least one oil hole, a pin is inserted into the oil hole which has a smaller diameter than that drilling

-has and is covered with a solder foil, the thickness of which is equal to the gap between the hole and the pin.

29. The method according to any one of claims 20 to 28, characterized in that all the individual parts are finished before soldering "or, as far as the pins are concerned, at least to a small degree of finishing and after soldering and ^' if necessary, subsequent Treatment methods only have to be ground finely.

30. The method according to any one of claims 20 to 29, characterized in that mutually engaging parts of the crankshaft are shrunk onto one another before soldering.