JP4744825B2 - Crankshaft - Google Patents

Description

  The present invention has at least one bearing pin and at least one crankpin radially offset thereto, the bearing pin and the crankpin projecting in the opposite direction from the crank web connecting them, A rear region having a relatively large diameter, in which the bearing pin and / or the crankpin are engaged with a hole provided in the crank web and are connected to the crank web by a shrinkage connection and hit rearward in the insertion direction; In particular, it relates to a crankshaft for a short stroke engine, in particular configured as a large diesel engine, having an engaging strut with a tapered front region along the insertion direction.

  This type of crankshaft is known from US Pat. In the case of large engines, it is often necessary to assemble the crankshaft that penetrates all cylinders from small structural members in order to reduce the finished weight. In that case, the same type of pins (usually bearing pins) that are connected to the corresponding crank web by shrinkage coupling, and another pin (usually a crank pin) that is formed to fit the corresponding crank web And a crankshaft in which both the bearing pin and the crankpin are contracted in the corresponding holes of the crank web.

In the case of a short stroke engine, it must be assumed that the radial distance between the bearing pin and the crank pin is within or within the region of the sum of the pin radii. However, according to the arrangement that can be read from Patent Document 1, the rear region and the front region of the engagement strut are arranged in the rear region so that the crank web is not weakened by the hole corresponding to the engagement strut. The dimensions are adjusted step by step so that the diameter is smaller than the region. However, in order to achieve shrinkage coupling, the pin diameter needs to be larger than the corresponding hole diameter, which corresponds to a certain percentage of the hole diameter, and therefore a relatively large rear diameter and correspondingly. Enlarged engagement strut area expands the corresponding area of the crank web after contraction coupling, resulting in a smaller diameter in the front area with a relatively small excess, as shown in FIG. There is a risk that a gap will form between the front region of the engaging strut and the crank web hole corresponding to this region. Thereby, when a load is applied, the entire force flow passes through the rear region of the engaging strut, which has an undesirable effect on torque transmission strength.
DK-PS 122 682

  From the above situation, the object of the present invention is to improve the above kind of crankshaft by simple and cost-effective means so that a relatively large torque can be transmitted while avoiding defects due to the known arrangement. It is in.

  This object is based on the invention in that the front region of the engagement strut as viewed in the insertion direction is connected to the rear region of the engagement strut, which is formed into a tapered cone as viewed in the insertion direction and to the crank web This is solved by mounting a stop ring for preventing the engagement strut from moving in the axial direction.

  By such measures, the above-mentioned drawbacks of the prior art are completely avoided while maintaining the advantages. Since the cone follows the rear region of the engagement strut, neither the engagement strut nor the corresponding crank web hole need to be stepped in size, there is no risk of gaps, and it is ensured over the entire length of the engagement strut. Secure contraction. Moreover, since a relatively small diameter can be achieved at the tip of the front cone, a relatively large amount of material remains on the arm side, and weakening of the crank web is avoided. On the other hand, the average diameter of the cone is essentially larger than the front tip diameter, which is advantageous in terms of the transfer torque that it can achieve. The conical form of the engaging struts certainly causes an axial acting force. The resulting axial movement reduces the meshing width in the rear region of the engaging strut and makes it impossible to achieve a contraction connection in the front region, but this is reliably eliminated by the installation of a restraining device.

  In the measures described in the preamble, advantageous embodiments and suitable improvements are described in the dependent claims.

  As a particularly preferred embodiment, the restraining device may take a form including at least one retaining ring that meshes with the outer circumferential cutout groove of the engagement pin and the cutout groove opened on the hole side of the crank web. The stop ring can advantageously have a relatively large width so that the axially acting pressure is relatively small. In addition, it is recognized that the retaining ring can be made of a material that is very suitable for fitting, which is different from the crank web material, thereby ensuring a very high stability.

  The stop ring may be useful if configured as an open ring with a slit. In this case, the retaining ring is in the form of a piston ring, and simple assembly of the piston ring type is guaranteed.

  As yet another appropriate countermeasure, the depth of the hole-side notch groove can be configured to correspond to a ring diameter obtained by subtracting at least the assumed contraction width. With this measure, the retaining ring can be inserted into the hole-side notch groove during assembly, and the engagement strut can be easily introduced into the arm-side hole.

  In the measures described in the preamble, as another advantageous embodiment, the structure of the restraining device is configured so as to mesh with a notch groove of a corresponding component formed in conformity with the wall surface of the engaging strut or the arm side hole, and its height. It is possible to include at least one web that is at least partly swiveled to the extent that corresponds at most to the expected shrinkage width. In this embodiment, advantageously no additional components are required.

  In any case, it is advantageous to install the restraining device in the boundary region between the front region and the rear region of the engaging strut. Thereby, a low level maintenance state of the bending stress acting on the action mechanism of the restraining device is ensured. Experiments also revealed that no significant stress concentration occurred in the crank web region when this measure was adopted.

  As yet another embodiment, for the formation of the restraining device, the engaging strut can be formed with a rising slope along the insertion direction, and a cone corresponding to the assumed contraction width can be formed even if the slope is maximum. In this case, preferably, an additional radial force is also generated by the axial force, which has an advantageous effect on the magnitude of the torque that can be transmitted.

  In the measures described in the preamble, other advantageous embodiments and suitable improvements are described in the remaining dependent claims, which will be considered in detail from the following description of the embodiments and with reference to the drawings. be able to.

  The main application area of the present invention is a short stroke two-stroke diesel engine having a large piston diameter, which is used as a large-sized engine, in particular, a ship prime mover. As an example of the size, a 12-cylinder large diesel engine having a cylinder hole diameter of 980 mm can be cited. In this case, in order to increase the rotation speed, the stroke is shortened from the conventional 2400 mm to about 1200 mm. This is a representative example, but of course it is not limited to this number.

  The crankshaft according to FIG. 1 has a crank web 1 with a bearing pin 2 on one side away from it and a crankpin radially offset on the other side on the other side. There are three. The radial distance between the bearing pin 2 and the crank pin 3 is smaller than half the sum of the pin diameters. FIG. 1 shows a bearing pin 2 and a crankpin 3. In the case of a crankshaft for a large engine, as is obvious, there are a plurality of bearing pins arranged coaxially one after the other and a plurality of crankpins parallel to the shaft that are shifted in position according to a predetermined ignition sequence. Has been deployed.

  The bearing pin 2 depicted in the figure is coupled to the crank web 1 by shrinkage coupling. The crankpin 3 in the same figure is integrally formed with the crank web 1. As a matter of course, an embodiment in which only the crank pin 3 or both the bearing pin 2 and the crank pin 3 are connected to the crank web 1 by contraction connection is also conceivable. The last-mentioned embodiment should be applied preferentially in the case of special large engines with a very high part weight.

  For each pin that is connected to the adjacent crank web by contraction connection, in this case the bearing pin 2 is provided with an engagement strut 5 that is fixed inside by a contraction connection that meshes with the corresponding hole 4 of the crank web 1. This corresponds to the rear as viewed in the insertion direction indicated by the arrow 6 and in this case has a cylindrical region 7, which has a relatively large diameter approximately corresponding to the diameter of the bearing pin 2, and It also has a region 8 that hits the front as viewed in the insertion direction, but its front tip diameter is smaller than the diameter of the rear region 7, so that the front tip of the engaging strut 5 of the bearing pin 2 and the connection of the crank pin 3 In the portion between the regions, the crank web 1 has a sufficiently thick width. In the embodiment according to FIG. 1, the front region 8 of the engagement strut 5 has an outer peripheral contour formed in the shape of a truncated cone. This portion is hereinafter referred to as a cone 9 for simplicity. The cone 9 is always located between the conical part region which is continuously connected to the rear region 7 of the engagement strut 5 and the front tip of the engagement strut. The hole 4 of the crank web 1 has a corresponding contour, and has a cylindrical cutting surface corresponding to the rear region 7 and a conical cutting surface corresponding to the front region 8. The front region 8 of the engagement strut 5 has a uniform tapered shape from the same diameter as the rear region 7 to a smaller front tip diameter, depending on the form of the cone 9.

  Since the cone 9 has a gradient, an axial force is generated in the direction opposite to the insertion direction due to the radial force generated in the contraction process. In order to prevent the engagement strut 5 from being pushed back by this axial force, a restraining device for preventing the axial movement of the engagement strut 5 is attached. In the case of the embodiment shown in FIG. 1, this meshes with the notch groove 11 on the outer peripheral side of the engaging strut 5 and simultaneously with the notch groove 12 opened on the hole side of the crank web 1 which is coplanar. Includes mating detent ring 10. The purpose of the retaining ring 10 is to be made of a material harder than the base material of the crankshaft, preferably spring steel, which is relatively wide in the radial direction.

  As is clear from FIG. 2, the retaining ring 10 has a slit 13 in the periphery. Accordingly, the retaining ring 10 can be expanded into a piston ring type during assembly. The retaining ring 10 is suitable for the purpose of being inserted into the notch groove 12 opened on the hole side of the heating crank web 1 during assembly, so that when the engagement pin 5 is pushed in, the spring action is applied. The engagement pin 5 is fitted into the outer peripheral cutout groove 11. In order to enable this process of operation, the notch groove 12 has a depth corresponding at least to the radial width of the retaining ring 10 minus the radial shrinkage width occurring in the region of the notch groove 12. . Since the crank web 1 is heated at the time of assembly, it is possible to subtract this contraction width. Since the retaining ring 10 of this example is disposed in the boundary region between the rear cylindrical region 7 and the front conical region 8 of the engaging strut 5, both the bending stress of the retaining ring 10 and the stress concentration in the region of the crank web 1 are extremely high. Can be assumed to be small.

  In the embodiment according to FIG. 3, a full or partial swivel web 14 is fitted as a restraining mechanism, which is shaped to fit the engagement strut 5 and the corresponding hole in the crank web 1 is attached. It meshes with a notch groove 15 opened to the side. The ridge height h that the web 14 protrudes from the maximum diameter of the engaging strut 5, in this case the diameter of the rear region 7 of the engaging strut 5, is at most a contraction that can be assumed in the notch groove 15 region of the arm 1. It is about the width. Thus, when the engaging strut 5 having the web 14 is inserted into the corresponding hole 4 of the heated crank web, reliable workability is ensured. The web 14 is engaged with the notch groove 15 coplanar with the web 14 during the cooling process of the crank web 1. This notch groove can be made larger at least in the radial direction in order to avoid the action of a forcing force. In the example depicted in the figure, the axial width is slightly larger.

  The web 15 is laterally assisted by lateral grooves 16 to avoid stress loading at the notch. In other respects, the embodiment of FIG. 3 corresponds to the embodiment of FIG. This is also true for the arrangement of the restraining device forming web 14 in the boundary region between the rear region 7 and the front region 8 of the engaging strut 5.

  Another embodiment is depicted in FIG. In this case, the rear region 7 corresponding to the rear portion of the engagement strut 5 when viewed in the insertion direction has a truncated cone-shaped side surface (hereinafter referred to as a cone 17) that is inclined upward along the insertion direction. . Accordingly, the cone 17 has a tapered shape opposite to the cone 9 disposed in the front region 8 of the engaging strut 5. The same applies to the holes 4 in the crank web 1 corresponding to the engaging struts 5. In the hole 4, a circumferential groove 18 is provided in a boundary region between both portions corresponding to the rear region 7 and the front region 8 of the engagement strut 5 in order to avoid a notch stress load.

  The raised height h ′ of the cone 17 with respect to the rear diameter in the rear region 7 of the engagement strut 5, that is, the difference between the maximum radius and the minimum radius in the rear region 7 of the engagement strut 5 is at most that of the hole 4 of the crank web 1. The engagement strut 5 can be inserted into the hole 4 of the heated crank web 1 since it corresponds to the assumed contraction width in the rear region. Since the gradient of the cone 17 is opposite to the gradient of the cone 9, the engagement strut 5 is prevented from moving in the axial direction with respect to the crank web 1. The axial force generated in the region of the cone 9 increases the effective radial force acting in the region of the cone 17 and consequently increases the load resistance of the contraction coupling.

  In a further embodiment based on FIG. 5, the front region 8 of the engagement strut 5 is divided into two parts. That is, a truncated cone shape that is tapered along the insertion direction (hereinafter referred to as a cone 19), a first section connected to the rear region 7, and a truncated cone that is inclined upward along the insertion direction A second section connected to the cone 19 (hereinafter referred to as the cone 20). In this case, the cone 20 facing away from the cone 19 functions as a restraining device that stops the axial movement of the engagement strut 5 relative to the crank web 1. The difference between the minimum radius of both cones 19 and 20 and the maximum diameter of the cone 20 corresponding to the front face of the engaging strut 5 that hits the front in the insertion direction, that is, the height h 'of the upslope is at most This is a degree corresponding to an assumed contraction width in a boundary region between both portions of the hole 4 of the crank web 1 corresponding to the cones 19 and 20. The rear region 7 of the engaging strut 5 can in this case be cylindrical.

  While the embodiments of the present invention have been described in detail in several examples, as described above, the embodiments are not exhaustive. Although not described in detail, other embodiments are also conceivable, such as the use of a spring-loaded stop pin for a stop device configuration. It would be equally conceivable to provide a plurality of stop devices of the same or different kind in the area of each engaging strut 5. Accordingly, the invention is not limited to the described embodiments.

1 is a partial cross-sectional view of a portion of a crankshaft according to the present invention. 2 is a partial view of a stop ring forming a stop device according to the embodiment of FIG. FIG. 3 shows an alternative to the embodiment of FIGS. 1 and 2 with a restraining web formed to fit the engaging struts. FIG. 6 is an illustration of another embodiment having a cone for forming a restraining device formed to fit the rear region of the engaging strut. FIG. 10 is an illustration of another alternative means that the front region of the engaging strut has two cones with opposite orientations. 1 is a partial view of a tapered engagement strut according to the prior art. FIG.

Explanation of symbols

1 Crank web
2 Bearing pin
3 Crankpin
4 Arm hole
5 engaging struts
6 arrows
7 Rear area
8 Front area
9 Cone
10 Retaining ring
11 Outer groove
12 Notch groove opened on the hole side
13 Slit
14 Web
15 Notch groove
16 groove
17 cone
18 Circumferential groove
19 cone
20 cones

Claims (8)

Having at least one bearing pin (2) and at least one crankpin (3) radially offset thereto, said bearing pin (2) and crankpin (3) connecting them Projecting in the opposite direction from the crank web (1), the bearing pin (2) and / or the crank pin (3) mesh with a hole (4) provided in the crank web (1), and the crank web ( 1) and a rear region (7) having a relatively large diameter, which is rearward when viewed in the insertion direction and, unlike it, a tapered front region (8) along the insertion direction. A crankshaft for a short stroke engine, in particular configured as a large diesel engine, with an engaging strut (5),
A front region (8) that hits the front when viewed in the insertion direction of the engagement strut (5) is connected to a rear region (7) of the engagement strut, and the tapered cone (9, 19) along the insertion direction. And a stop device for preventing the axial movement of the engagement strut (5) relative to the crank web (1) ,
The stop device engages at least one stop ring (10) which engages with a notch groove (11) on the outer peripheral side of the engaging strut (5) and a notch groove (12) opened on the hole side of the crank web (1). Including
The retaining ring (10) is made of a material harder than the base material of the crankshaft;
The depth of the notch groove (12) opened on the hole side corresponds to at least the radial width of the retaining ring (10) excluding the assumed contraction width in the region of the notch groove (12). A featured crankshaft. Crank shaft according to claim 1, wherein the retaining ring (10), characterized in that it is configured as an open ring with a radial slit (13). Crank shaft according to claim 1, wherein the retaining ring (10) is characterized in that it consists of spring steel.   The restraining device is formed to fit the wall of the engaging strut (5) or the arm-side hole (4) and is at least partially pivoted to the corresponding notch groove (15) of each opposing component. 2. The crankshaft according to claim 1, comprising a web (14) corresponding to an assumed contraction width in the region of the notch groove (15) at the maximum in the radial direction (h). The restraining device, according to any one of claims 1 to 4, characterized in that provided in the boundary region between the rear area and the front area (7, 8) engaging the strut (5) Crankshaft.   The engagement strut (5) is provided with a cone (17 or 20) which is inclined upward in the insertion direction to form the restraining device, the height of the gradient (h ′) 2. The crankshaft according to claim 1, wherein is at most a degree corresponding to a contraction width of a corresponding region of the arm hole. Crank according to claim 6 , characterized in that the rear region (7) of the engagement strut (5) is at least partly provided with a cone (17) which is inclined upward in the insertion direction. shaft. The front region (8) of the engagement strut (5) comprises a cone (20) which is inclined upward in the insertion direction, the cone (20) being tapered in the insertion direction ( The crankshaft according to claim 7 , wherein the crankshaft is connected to the front side in the insertion direction of the tapered cone.

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