Crankshaft having at least one counterweight

Abstract

The present disclosure shows a crankshaft having at least one counterweight that is preferably screwed to the crankshaft via at least two screws, with the counterweight having a contact surface at which it contacts a counter-contact surface of the crankshaft. In this respect, the position of the counterweight at the crankshaft is fixed via at least one positioning element independent of the screw connection.

Claims

1. A crankshaft having: at least one counterweight that is screwed to the crankshaft, wherein the counterweight has a contact surface at which it contacts a counter-contact surface, and wherein the contact surface extends in a plane that extends in parallel with the axis of the crankshaft; and at least two screws by means of which the counterweight is screwed to the crankshaft; wherein a position of the counterweight at the crankshaft is fixed via at least a first and a second positioning element independent of the screw connection; wherein the first positioning element is arranged in a first plane extending perpendicular to the axis of the crankshaft; and wherein the second positioning element is extending in a second plane extending perpendicular to the axis of the crankshaft, the second plane being spaced apart from the first plane in a direction of the axis of the crankshaft.

2. The crankshaft in accordance with claim 1, wherein each positioning element is at least one positioning pin and an associated positioning cutout in which said positioning pin engages.

3. The crankshaft in accordance with claim 1, wherein the at least one positioning element is provided spaced apart from the at least one screw connection.

4. The crankshaft in accordance with claim 1, wherein the positioning pin or pins engage into positioning cutouts that are aligned with one another in the counterweight and in the crankshaft.

5. The crankshaft in accordance with claim 1, wherein the first plane is a center plane of the counterweight extending perpendicular to the axis of the crankshaft and/or a screw connection plane of the counterweight spanned by the longitudinal axes of two screws.

6. The crankshaft in accordance with claim 1, wherein the first and second positioning elements are arranged within the counter-contact surface and/or contact surface.

7. The crankshaft in accordance with claim 1, wherein the first and second positioning elements are each associated with a screw and/or are further spaced apart from one another than the screws.

8. A crankshaft having: at least one counterweight that is screwed to the crankshaft; and at least two screws by means of which the counterweight is screwed to the crankshaft; wherein the counterweight has a contact surface at which it contacts a counter-contact surface; wherein a position of the counterweight at the crankshaft is fixed via at least a first and a second positioning element independent of the screw connection; wherein the contact surface has at least a first and a second mutually separate contact region that are each associated with one of the two screws, the first and second contact regions being separated by a recess; and wherein the first positioning element is arranged in the first contact region and the second positioning element is arranged in the second contact region.

9. The crankshaft in accordance with claim 8, wherein the contact regions respectively completely surround one of the two screws; and/or wherein the screws are each substantially arranged at the center of one of the contact regions.

10. The crankshaft in accordance with claim 8, wherein the contact regions extend in a common plane and/or are arranged symmetrically with respect to a center plane of the counterweight extending in the axial direction of the crankshaft.

11. The crankshaft in accordance with claim 1, wherein the contact surface is produced by cutting machining of a raw part.

12. The crankshaft in accordance with claim 1, wherein the contact surface extends in a plane that extends in parallel with the axis of the crankshaft and/or perpendicular on a center plane of the counterweight extending in an axial direction of the crankshaft.

13. A crankshaft having: at least one counterweight, wherein the counterweight has a contact surface at which it contacts a counter-contact surface of the crankshaft; two screws by means of which the counterweight is screwed to the crankshaft; and two positioning elements that are spaced apart from the screws and by means of which a position of the counterweight at the crankshaft is fixed; wherein the spacing between the two positioning elements is greater than the spacing between the two screws.

14. A counterweight for a crankshaft in accordance with claim 1.

15. An internal combustion engine comprising a crankshaft in accordance with claim 1.

16. A machine having an internal combustion engine in accordance with claim 15.

17. A counterweight for the crankshaft in accordance with claim 8.

18. A counterweight for the crankshaft in accordance with claim 13.

19. The crankshaft in accordance with claim 1, wherein a spacing between the first and second positioning elements is greater than a spacing between the two screws.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The present disclosure will now be described in more detail with reference to embodiments and to drawings.

(2) There are shown:

(3) FIG. 1: an embodiment of a crankshaft having at least one counterweight in a view from an axial direction;

(4) FIGS. 2a and 2b: two embodiments of counterweights;

(5) FIG. 3a to FIG. 3c: an embodiment of a counterweight in accordance with the prior art;

(6) FIG. 4: an embodiment of a counterweight in accordance with the disclosure; and

(7) FIG. 5: the embodiment of FIG. 4 in a view from below and from the side; and

(8) FIG. 6: a detail view of the embodiment of FIGS. 4 and 5.

DETAILED DESCRIPTION

(9) FIG. 1 shows an embodiment of a crankshaft 1 having a counterweight 6.

(10) The embodiment of the crankshaft shown in FIG. 1 and described in more detail in the following is used both with crankshafts in accordance with the prior art and with crankshafts in accordance with the present disclosure and is therefore shown in common for both embodiments in the following.

(11) The crankshaft 1 has main bearing regions that are not shown in more detail in FIG. 1 and via which the crankshaft is supported at main bearings of the engine rotatable about the axis 2. Such main bearing regions are here provided between all the cranks of the crankshaft and at the two outer ends of the crankshaft.

(12) The crankshaft 11 further comprises crankpins 3 at which connection rods are supported via which the crankshaft is connected to pistons of the internal combustion engine. The crankpins 3 here respectively extend between crankwebs 5 of the crankshaft that connect the crankpins 3 to the main bearing regions. The axis of the crankpins 3 is marked by “4” and here represents the axis of rotation about which the connecting rods rotate.

(13) Counterweights 6 are furthermore provided at the crankshaft that may be arranged at the crankwebs 5. Only one single crankweb having a counterweight 6 arranged thereon is shown in FIG. 1 in this respect.

(14) In the possible embodiment, every crankweb 5 can have a counterweight 6. Alternatively, also only individual crankwebs can have counterweights 6 such as described in more detail in the following, while other crankwebs either have no counterweights at all or have differently designed counterweights, for example counterweights produced, for example forged, in one piece with the crankshaft.

(15) The counterweight 6 is screwed to the crankshaft via screws 11. The counterweight 6 here has a contact surface 7 at which it contacts a counter-bearing surface 8. The contact surface 7 and the contact surface 8 are pressed with one another via the screws 11.

(16) In the embodiment, the counter-contact surface 8 is arranged at the crankweb 5. The counterweight 6 is hereby screwed to the crankweb 5. In this respect, bores 17 not shown in FIG. 2 pass through the counterweight 6. The screws 11 extend through these bores through the counterweight to the crankshaft 5. The crankwebs have corresponding threaded bores in which the screws 11 are screwed. The screw heads lie on an outer peripheral surface of the counterweight 6.

(17) In the embodiment, a plurality of screws 11 are provided whose longitudinal axes are arranged in parallel with one another. Two screws 11 are specifically used in the embodiment.

(18) The counterweight has mirror symmetry with respect to a plane of symmetry extending in the axial direction. The contact surface 7 and the counter-contact surface 8 here are perpendicular on this plane.

(19) The counterweight is arranged at the crankshaft such that the axis 2 of the crankshaft extends in the plane of symmetry.

(20) In the embodiment, the counterweight 6 is arranged without any angular offset on the side of the crankweb 5 disposed opposite the crankpin 3, that is the plane of symmetry of the counterweight 6 is a plane that is spanned by the axis 2 of the crankshaft and the axis 4 of the crankpin 3.

(21) The outer periphery of the counterweight 6 has a centrally arranged cutout 10 in whose base region the bores 17 for the screws are arranged, with the heads of the screws being supported on the base region of the cutout surrounding the bores 17.

(22) The outer periphery of the counterweight 6 furthermore has convexly curved sections 14 and 15 that extend at both sides of the cutout 10 for the screws 11. In a first curved region 14 adjoining the cutout 10, the outer periphery has a radius of curvature 12 whose center 27 lies on the connection line between the axis 2 of the crankshaft and the axis 4 of the crankpin 3.

(23) In the embodiment, the center 27 is here closer to the axis 4 of the crankpin and divides the distance between the axis 4 of the crankpin 3 and the axis 2 of the crankshaft 1 in a ratio of approximately 1:3.

(24) The two first regions 14 each extend over an angular range with respect to the axis 2 of the crankshaft between 10 and 40 degrees, such as between 15 and 30 degrees. In the embodiment, the two first regions extend approximately between an angle of 20 degrees, measured from the center line or the plane of symmetry of the counterweight, up to an angle of approximately 43 degrees with respect to the axis 2 of the crankshaft.

(25) A respective second convexly curved region 15 having a smaller radius of curvature 13 adjoins the first convexly curved region 14. The radius in the second region 15 only amounts to approximately one third of the radius in the first region 14.

(26) The second convexly curved regions 15 form the outer end of the outer peripheral surface of the counterweight. Here, they merge with a small radius of curvature into regions of the inner peripheral surface of the counterweight that extend outwardly from the contact surface.

(27) The counterweight 6 has material regions 17 at both sides of the contact surface 7 that are arranged on the side of the axis 2 defined with respect to the plane defined by the contact surface 7, that is arranged closer to the axis 2 than to the plane of the contact surface 7. These material regions 17 have termination surfaces 28 that extend inwardly in each case in parallel with the contact surface 7 from the outer end of the second section 15 and are connected to the contact surface 7 at their inner ends via bent sections.

(28) The counterweight 6 thus has a mushroom-like shape together with the crankweb 5 at which it is arranged.

(29) Two different embodiments for counterweights 6 are shown in FIGS. 2a and 2b that only differ with respect to the cutout 10 for the screws 11. They otherwise correspond to the counterweights described with respect to FIG. 1.

(30) The counterweight shown in FIG. 2b here corresponds to the counterweight shown in FIG. 1 and has a single continuous cutout in a base region extending in parallel with the contact surface 7. In the embodiment shown in FIG. 2a, in contrast, an elevated portion 16 is provided between the regions for the two screws 11. It could in principle reach up to the radius 12. However, it remains below the radius in the embodiment.

(31) In a possible embodiment, both counterweights in accordance with FIG. 2a and counterweights in accordance with FIG. 2b can be arranged at a single crankshaft. The cranks arranged centrally at the crankshaft can have counterweights in accordance with FIG. 2a, all the other cranks can have counterweights in accordance with FIG. 2b. Other mixes and embodiments are, however, also conceivable.

(32) In all the embodiments, the cutout 10 extends over the total axial width of the counterweight. The screw heads of the screws 11 are hereby axially accessible. With wider counterweights, it would, however, also be conceivable that the cutout 10 or the corresponding cutouts for the screw heads are cutouts that do not extend over the total axial width of the counterweight, but are rather, for example, let into the then continuous curved region in the form of blind holes.

(33) The counterweight is here substantially of plate shape, with the main plane of the counterweight being perpendicular to the axis of the crankshaft.

(34) As can in particular be seen from FIG. 3a, the counterweight, however, has lateral chamfers 30 in the region of its convexly curved periphery 9. They serve to avoid collisions with components of the engine, the connecting rod, the piston, or the cylinder.

(35) The embodiment of the crankshaft and of the counterweight shown in FIGS. 1 and 2 is initially known. As presented in detail in the general part of the description, the shape of the counterweight and in particular the shape of the convex peripheral region of the counterweight serve to position as much material and thus mass as possible as far away as possible from the axis 2 of the crankshaft without thus colliding with interfering contours. The radius of the section 14 can here be greater than the spacing of the axis 2 from the crankshaft because the relative interfering contour in this region is formed by the piston that, however, does not represent a fixed interfering contour, but is in turn moved into the cylinder again after reaching the bottom dead center and therefore permits a shape of the counterweight in which the radius is greater in the region 14 than the spacing from the crankshaft 2.

(36) The present disclosure therefore does not deal with these very well-known aspects of the design of a crankshaft, but rather with the specific connection between the counterweight and the crankshaft. This configuration in accordance with the disclosure of this connection can therefore be used independently of the shape of the counterweight with all the counterweights screwed to the crankshaft.

(37) The connection to the crankshaft is shown in FIGS. 3 to 6 for an embodiment of a counterweight in accordance with the prior art. It has a single contiguous contact surface 20 within which the two bores 17 for the screws are provided.

(38) Extended sections 18 into which first ends of centering sleeves 19 engage to position the counterweights at the crankshaft are provided to center the counterweight in this respect in the lower end section of the bores 17 facing the crankshaft.

(39) The crankshaft likewise has a contiguous counter-contact surface 8 that is pressed with the contact surface 20.

(40) Bores 17′ into which the screws 17 are screwed and that are aligned with the bores 17 of the counterweight are provided in the counter-contact surface 8 of the crankshaft or the crankweb. The end sections 17′ facing the counterweight 17 have extended sections 18′ that are aligned with the extended sections 18 of the counterweight and into which the other ends of the centering sleeves engage.

(41) The outer peripheries of the centering sleeves 19 are pressed into the extended sections 18 and 18′. They surround the screws 11, with a gap remaining between their inner peripheries and the outer peripheries.

(42) An embodiment of a connection in accordance with the disclosure to the crankshaft is shown in FIGS. 4 to 6 in contrast.

(43) In accordance with a first aspect of the present disclosure, the contact surface 20 is split in accordance with the disclosure into two contact regions 21 and 22 that are separate from one another and that are each associated with one of the bores 17 for the screws. The first contact region 21 is therefore in particular associated with the one screw, the second contact region 22 with the other screw.

(44) The contact regions 21 and 22 in particular each surround one of the bores 17. A region 25 in which the counterweight does not lie on the counter-contact surface is provided between the two contact regions 21 and 22.

(45) In the embodiment, the counterweight is designed as a casting and/or as a forged part. The contact regions 21 and 22 are produced in a cutting process. Cast marks 19 of the mold can be recognized in the Figures here.

(46) The contact regions 21 and 22 have an approximately quadratic basic shape at whose center the respective bore 17 is arranged. A substantially more concentrated force transmission between the counterweight and the crankshaft or the crankweb, by which a canting and inaccuracies in the placement are avoided, is hereby produced in comparison with the contiguous substantially larger contact surface 20 in accordance with the prior art.

(47) In the embodiment, the two contact regions 21 and 22 extend over the total axial width of the counterweight and can hereby be produced relatively simple by a cutting machining of this region of the counterweight. The raw part therefore has a raised region whose height is reduced by the cutting machining, but is not reduced to zero, in the region of the contact regions 21 and 22 in comparison with the interposed region 25 and in comparison with the outwardly disposed regions.

(48) The counter-contact surface 8 at the crankshaft or crankweb is furthermore produced as contagious in the embodiment, but could likewise have two separate regions that would correspond to the two contact regions 21 and 22.

(49) In accordance with a second aspect of the present disclosure, the positioning of the counterweights at the crankshaft or crankweb takes place via positioning bores 23 and 24 that are provided separately from the bores 17 for the screw connections in the counterweight.

(50) Positioning pins 26 that position the counterweights at the crankshaft or crankweb engage into the bores 23 and 24.

(51) The axes of the positioning bore 23 and 24 or positioning pins 26 extend in parallel with the axes of the bores 17 for the screw connection.

(52) In the embodiment, a first positioning bore 23 is arranged in a plane that is defined by the center axes of the two bores 17 for the screw connections. The second positioning bore 24 is in contrast laterally displaced with respect to this plane. The plane defined by the two bores 17 can here form a center plane of the counterweight in the axial direction can, however, also be slightly displaced with respect to such a center plane.

(53) The positioning bores 23 and 24 and the corresponding positioning elements 26 are disposed further apart than the bores 17 for the screw connections. They are in particular each disposed laterally next to the bores 17 for the screw connections in the peripheral direction.

(54) Bores 17′ into which the screws 17 are screwed and that are aligned with the bores 17 of the counterweight are provided in the counter-contact surface 8 of the crankshaft or the crankweb.

(55) Positioning bores 23′ and 24′ are furthermore provided in the counter-contact surface 8 that are aligned with the positioning ores 23 and 24 of the counterweight and into which the positioning pins 26 engage. The positioning bores 23′ and 24′ are thus likewise provided separately from the bores 17′ for the screw connection and are spaced apart therefrom.

(56) The outer peripheries of the positioning pins are pressed into the positioning bores 23, 23′ and 24, 24′. In the embodiment, the positioning pins 26 are solid, circular cylindrical elements.

(57) The three aspects of the present disclosure can also be used independently of one another. The separate contact regions could in particular also be used with a positioning via positioning sleeves such as are known from the prior art. The positioning elements in accordance with the second aspect could furthermore also be used in a contiguous contact surface such as was used in the prior art. The positioning elements could in particular be arranged within such a contiguous contact surface and the positioning bores could in particular be introduced into them.

(58) Both aspects, however, may be combined such as is also the case in the embodiment.

(59) In the embodiment, the positioning bores are each introduced into the contact regions 21 and 22 and are therefore each surrounded thereby. The positioning bore 23 is here specifically arranged in the region of the contact region 21, the positioning bore 24 in the region of the contact region 22. In other words, the one bore 17 for one of the two screw connections and the positioning bore 23 are arranged in the region of the contact region 21 and the other bore 17 for the other screw connection and the second positioning bore 24 are arranged in the region of the contact region 22. The positioning pins that engage into the positioning bores are arranged in the region of the counter-contact surface.

(60) As described above, the positions of the positioning bores and positioning pins can be swapped over in an alternative embodiment with respect to the embodiment shown.

(61) The bores 17 pass as described above through the counterweight such that the screw heads lie in the region of the cutout 10 and the counterweight is rigidly connected to the crankshaft by the screws passing through the counterweight.

(62) The positioning bores 23, 23′ and 24, 24′ in contrast are blind holes in the embodiment. The bores 17′ for the screws in the crankshaft or crankweb are equally designed as blind holes.

(63) In a possible embodiment of the present disclosure, the counterweights and the crankshaft can be designed according to scale as is shown in the drawings. All the geometrical ratios that are shown in the Figures can therefore be implemented in exactly the form shown. The radii of curvature and the specific shapes can here in particular also be implemented in exactly its form as shown in the Figures. The same applies to the relative positioning and size of the respective elements.

(64) In alternative embodiments of the present disclosures, the drawings can, however, also only serve as a schematic base for the configuration of the crankshaft and the counterweights and different specific shapes, dimensions, and ratios can be selected than shown in the drawings.

(65) The present disclosure can furthermore also be used independently of the form of the counterweights shown in the drawings.

(66) The present disclosure and the described crankshaft can be used in any desired internal combustion engines.

(67) The present disclosure can in this respect be used in V engines. The connecting rods of two cylinders of a V segment can in particular be supported at a crankpin in such an embodiment.

(68) The arrangement of the cranks at the crankshaft can here take place symmetrically with respect to a center plane of the crank or asymmetrically.

(69) The present disclosure can in particular be used with larger engines, for example with engines having at least 12 cylinders. The present disclosure can in particular be used here with engines having 12 cylinders, 16 cylinders, or 20 cylinders. These engines are in particular designed as V engines.

(70) The engine can, for example, be a diesel engine or a gasoline engine.

(71) The engine can be used to drive mobile or stationary machines, for example to drive earthmovers such as excavators or dumper trucks, or for stationary applications such as for engine-generator units to generate electrical power.