WO2009132695A1

WO2009132695A1 - Method of manufacturing a crankshaft and crankshaft manufactured according to the method

Info

Publication number: WO2009132695A1
Application number: PCT/EP2008/055252
Authority: WO
Inventors: Lambertus Hendrik De Gooijer
Original assignee: Gomecsys B.V.
Priority date: 2008-04-29
Filing date: 2008-04-29
Publication date: 2009-11-05

Abstract

A method of manufacturing a crankshaft (12) comprises the following steps: supplying an intermediary crankshaft (1) made of one piece and comprising at least an intermediary crank arm (3) and an intermediary crankpin (4); applying a first positioning indicator (5) on the intermediary crank arm (3) and a second positioning indicator (6) on the intermediary crankpin (4) of the intermediary crankshaft (1) defining a relative angular position of the intermediary crank arm (3) and the intermediary crankpin (4) about a centre line of the intermediary crankpin (4); separating the intermediary crank arm (3) and the intermediary crankpin (4); manufacturing an intermediary crank arm hole (8) in the intermediary crank arm (3); inserting a portion of the intermediary crank-pin (4) into the intermediary crank arm hole (8); adjusting the positions of the intermediary crankpin (4) and the intermediary crank arm (3) with respect to each other such that the first and second positioning indicators (5, 6) substantially have the same relative position in rotational direction about the centre line of the intermediary crankpin (4) as in case of the intermediary crankshaft (1); and fixing the intermediary crank arm (3) and the intermediary crankpin (4) to each other, thus forming the crankshaft (12).

Description

METHOD OF MANUFACTURING A CRANKSHAFT AND CRANKSHAFT MANUFACTURED ACCORDING TO THE METHOD

The invention relates to a method of manufacturing a crankshaft.

Crankshafts for reciprocating piston mechanisms are usually formed of one piece. In certain cases it is desired to assemble a crankshaft from separate parts, for example in case of a reciprocating piston mechanism wherein non- separated parts need to be fitted onto the crankpin, such as a connecting rod made of one piece. For example, the international patent application PCT/EP2008/051727 of the same applicant as the current application discloses a reciprocating piston mechanism in which a crankshaft made of separate parts is desired for assembling the mechanism.

The object of the invention is to provide an innovative method of manufacturing a crankshaft. This object is accomplished with the method according to claim 1. Due to this method the crankshaft can be assembled such that the rotational position of the crankpin and the crank arm about the centre line of the crankpin are similar to that of the intermediary crankpin and the interme- diary crank arm of the intermediary crankshaft. When the first positioning indicator and the second positioning indicator have the same relative position as in case of the intermediary crankshaft, the crank arm and the crankpin of the crankshaft are in the same relative position as that of the intermediary crankpin and the intermediary crank arm of the intermediary crankshaft. The method provides the opportunity to prepare the intermediary crankshaft before the manufacturing method such that it is directly ready for use as the crankshaft after fixing the intermediary crankpin and the intermediary crank arm.

It is noted that an element preceded by the word 'intermediary' herein should be interpreted as an element which is modified during the method of manufacturing. When the preceding word intermediary' is omitted the element is in its final state after manufacturing. The first positioning indicator and the second positioning indicator may be aligned in axial direction of the intermediary crankshaft. In this case the difference in angular position between the first positioning indicator and the second positioning indicator is zero, such that when adjusting the intermediary crankpin and the intermediary crank arm with respect to each other the first and second positioning indicators can be aligned, which makes the adjustment operation simple. Furthermore, the application of the first positioning indicator and the second positioning indicator on the intermediary crankshaft is relatively simple, because both indicators can be applied along a straight line.

The first positioning indicator may be applied by manufacturing a first recess in the intermediary crank arm to such a depth that it ends at a location within the enveloping edge of the intended intermediary crank arm hole, and the second positioning indicator may be applied by manufacturing a second recess in the intermediary crank pin, wherein the first and second recesses are located on the intermediary crankshaft such that after inserting the portion of the intermediary crankpin into the intermediary crank arm hole, the first and second recesses can be aligned in a direction perpendicular to the centre line of the intermediary crankpin. As in practice the first recess will be manufactured before the intermediary crank arm hole is present, the word ^Λin- tended' is used. The advantage of this step is that after inserting the intermediary crankpin into the intermediary crank arm hole the second recess can be detected through the first recess, visually or tactically by means of an alignment element. For example an elongated alignment element can be put through the first recess in the direction of the intermediary crankpin until it touches the intermediary crankpin. When rotating the intermediary crankpin and the intermediary crank arm with respect to each other, the alignment element may fall into the second recess, thus aligning the first and second recess. In a preferred embodiment the first and second recesses are formed by machining a continuous slit in the intermediary crank arm and the intermediary crankpin. This simplifies the machining operation since only one slit has to be applied in order to reach the first recess in the intermediary crank arm and the second recess in the intermediary crankpin. In this case the single slit will have a continuous width along the slit, in practice.

The slit may extend over the entire length of the intermediary crank arm, as seen in axial direction of the intermediary crank shaft.

In a preferred embodiment the intermediary crank arm hole is a through-hole, thus forming intermediary crank arm parts separated at the intermediary crank arm slit after manufacturing the intermediary crank arm hole. Since the slit in the intermediary crank arm is applied to such a depth that it ends in the intermediary crank arm hole after manufacturing the hole, the intermediary crank arm parts are formed. As these parts are movable with respect to each other the inter- mediary crank arm and the intermediary crankpin can be fixed to each other by clamping the intermediary crank arm parts about the intermediary crankpin.

The intermediary crank arm and the intermediary crankpin can be separated by cutting the intermediary crank- pin at a joint portion of the intermediary crank arm and the intermediary crankpin.

The intermediary crankpin may be machined and adapted to fit in the hole of the intermediary crank arm before inserting the intermediary crankpin into the intermedi- ary crank arm hole. This may make the fitting operation easier .

The invention is also related to a crankshaft which is manufactured by the method as described hereinbefore. The invention will be explained in more detail hereinafter with reference to drawings, which are schematic representations of embodiments of the invention. Fig. 1 is a perspective view of an embodiment of the intermediary crankshaft according to the invention.

Fig. 2 is a similar view as Fig. 1, showing the intermediary crankshaft after one of the manufacturing steps. Fig. 3 is a similar view as Fig. 1, showing the intermediary crankshaft after several manufacturing steps.

Fig. 4 is a perspective view of the embodiment of a crankshaft manufactured according to the invention as shown in Fig. 1-3. Fig. 5 is a similar view as Fig. 3, but showing the parts of an embodiment of an intermediary crankshaft for a V8 internal combustion engine.

Fig. 6 is a similar view as Fig. 4 of the embodiment of Fig. 5 in assembled condition. Fig. 7 is a perspective view of a V8 internal combustion engine comprising the embodiment of Fig. 6.

Fig. 1-4 show different steps of a method of manufacturing a crankshaft according to the invention. Hereinafter, the elements indicated by the preceding word ^intermediary' should be interpreted as elements which are modified during the method of manufacturing. When the preceding word ^intermediary' is omitted the element is in its final state after manufacturing.

Fig. 1 shows an embodiment of an intermediary crankshaft 1, which is made of one piece. The intermediary crankshaft 1 can be manufactured according to a method which is known in the art, for example by forging. The embodiment of the intermediary crankshaft 1 as shown in Fig. 1 has a centre line 2 and comprises two intermediary crank arms 3 and two intermediary crankpins 4. The intermediary crankpins 4 have a larger length than required for a reciprocating piston mechanism where the resulting crankshaft is intended for, but the crankpins of the crankshaft after manufacturing will be shorter than the intermediary crankpins 4. The intermediary crankpin 4 has a circular cross- sectional shape and the intermediary crank arm 3 extends beyond the peripheral edge of the crankpin 4 in radial direction thereof. Furthermore, the intermediary crankpin 4 is provided with a counterweight. The intermediary crank arm 3 and the intermediary crankpin 4 are fixed to each other.

Starting with the intermediary crankshaft 1 as shown in Fig. 1, a first positioning indicator 5 on the intermediary crank arm 3 and a second positioning indicator β on the intermediary crankpin 4 of the intermediary crankshaft 1 are applied, which is illustrated in Fig. 2. In this case, the first positioning indicator 5 and the second positioning indicator 6 form a single continuous slit 5, 6 which is machined in the intermediary crank arm 3 and the intermediary crankpin 4. In this case the single slit 5, 6 has a continuous width along the slit 5, 6. The slit 5, 6 extends parallel to the centre line 2, and therefore the first positioning in- dicator 5 and the second positioning indicator 6 are aligned in this case. The depth of the slit 5, 6 at the intermediary crankpin 4 may be about 3mm, for example, but the value depends on the size of the intermediary crankshaft 1. In this embodiment the bottom of the slit 5, 6 extends parallel to the centre line 2, as well.

Fig. 2 shows that the slit 5, 6 extends substantially parallel to the centre line 2 over the entire length of the intermediary crank arm 3 as seen along the centre line 2. The slit 5, 6 can be machined by a cutting device having a certain cut width. Fig. 2 also shows a virtual circle 7, which represents the peripheral line or enveloping edge of the intermediary crankpin 4 when the intermediary crankpin 4 would be extended through the intermediary crank arm 3. It can be seen that the slit 5 at the intermediary crank arm 3 protrudes into the virtual circle 7, which is a consequence of the fact that the slit 5 has a certain depth at the intermediary crankpin 4 and the bottom of the slit 5, 6 extends substantially parallel to the centre line 2.

Fig. 3 shows a next stage in the manufacturing process of the crankshaft. The intermediary crankpins 4 are separated from the intermediary crank arms 3, leading to three separate parts of the intermediary crankshaft 1. Each of the slits 5, 6 are also separated into an intermediary crank arm slit 5 and an intermediary crankpin slit 6. Furthermore the intermediary crank arms 3 are each provided with an intermediary crank arm hole 8. The intermediary crank arm hole 8 is manufactured such that an end portion of the intermediary crankpin 4 fits into the intermediary crank arm hole 8. In the embodiment as shown in Fig. 3 the intermediary- crank arm hole 8 is a circular hole having a centre line which extends parallel to the centre line 2 of the intermedi- ary crankshaft 1 and its diameter is slightly larger than the outer diameter of the intermediary crankpin 4.

As a consequence of the intermediary crank arm slit 5 and the intermediary crank arm hole 8 the intermediary crank arm 3 is provided with two opposite intermediary crank arm parts 10, 11 which parts are movable with respect to each other. The intermediary crank arm hole 8 may be manufactured by drilling, for example. The separation of the intermediary crank arm 3 and the intermediary crankpin 4 may be performed by cutting the crankpin 4, for example at a joint portion 9 of the intermediary crankshaft 1, see Fig. 2.

Due to the corresponding intermediary crank arm slit 5 and the intermediary crankpin slit 6 the appropriate relative angular position of the intermediary crank arm 3 and the intermediary crankpin 4 can be easily determined, visu- ally and tactically. The alignment is further facilitated when an alignment element (not shown in Fig. 1-4) is inserted into the intermediary crank arm slit 5. In this case the intermediary crank arm 3 and the intermediary crankpin 4 can be adjusted until the alignment element fits in both slits 5 and 6. In this case, alignment of the slits 5, 6 in a direction perpendicular to the centre line 2 is achieved.

In a next step the intermediary crank arm 3 and the intermediary crankpin 4 are fixed to each other. This may be achieved by clamping the intermediary crank arm parts 10, 11 about the intermediary crankpin 4. Clamping is possible by a bolt and nut connection, for example. The bolt may be inserted in a through-hole 16 through both intermediary crank arm parts 10, 11. However, alternative clamping means are conceivable. In the embodiment as shown in Fig. 1-4, the in^¬ termediary crank arm 3 of the intermediary crankshaft 1 is provided with a relatively big extension with respect to the peripheral edge of the intermediary crankpin in order to provide sufficient material for making a hole 16 for a bolt therein.

Fig. 4 shows a final crankshaft 12 resulting from steps as illustrated in Fig. 1-3. The intermediary crankpin 4 has become a crankpin 13, and the intermediary crank arm 3 has become a crank arm 14.

Fig. 5 and 6 show an alternative embodiment of an intermediary crankshaft 1 and a crankshaft 12, respectively. The crankshaft 12 is intended for a V8 internal combustion engine as shown in Fig. 7. Fig. 5 and 6 also show an alignment element 15 which is fitted in the slit 5, 6. In this case the alignment element 15 may be a plate which fits in the intermediary crankpin slit 6, but which is slightly thinner than the intermediary crank arm slit 5. In that case, the alignment element 15 is used to align the intermediary crank arm slit 5 and the intermediary crankpin slit 6 in a direction perpendicular to the centre line 2, on the one hand, and to clamp the intermediary crank arm parts 10, 11 with a higher clamping force, on the other hand. Although the alignment element 15 is intended for aligning the intermediary crank arm slit 5 and the intermediary crankpin slit 6, it is also conceivable to use the aligning element 15 as a spline for fixing the intermediary crank arm 3 and the intermediary crankpin 4 in rotational di- rection, in addition to clamping the intermediary crank arm parts 10, 11 about the intermediary crankpin 4.

Fig. 7 shows the resulting crankshaft of Fig. 6 as used for a V8 internal combustion engine in assembled condition. It is noted that the crankshaft 12 as shown in Fig. 6 has only three bearings in order to minimize the length of the internal combustion engine. The invention is not limited to the embodiments shown in the figures, which can be varied in several ways within the scope of the invention. It is for example possible that the intermediary crank arm split 5 does not extend over the entire length of the intermediary crank arm, or the split 5, 6 is not a continuous slit but one slit in the intermediary crank arm and another one in the intermediary crankpin.

Claims

1. A method of manufacturing a crankshaft (12) comprising at least a crankpin (13) and a crank arm (14) which are fixed to each other, comprising the following steps : supplying an intermediary crankshaft (1) comprising at least an intermediary crank arm (3) and an intermediary crankpin (4), the intermediary crankshaft (1) being made of one piece; applying a first positioning indicator (5} on the intermediary crank arm (3) and a second positioning indicator (6) on the intermediary crankpin (4) of the intermediary crankshaft (1), wherein the first positioning indicator (5) and the second positioning indicator (6) define a relative angular position of the intermediary crank arm (3} and the intermediary crankpin (4) about a centre line of the intermediary crankpin (4); separating the intermediary crank arm (3) and the intermediary crankpin (4); manufacturing an intermediary crank arm hole (8) in the intermediary crank arm (3) such that a portion of the intermediary crankpin (4) fits in the intermediary crank arm hole (8); inserting said portion of the intermediary crankpin (4) into the intermediary crank arm hole (8); adjusting the positions of the intermediary crankpin (4) and the intermediary crank arm (3} with respect to each other such that the first and second positioning indicators (5, 6) substantially have the same relative position in rotational direction about the centre line of the interme- diary crankpin (4) as in case of the intermediary crankshaft (1) of one piece; fixing the intermediary crank arm (3) and the intermediary crankpin (4) to each other, thus forming the crankshaft (12), in which fixed state the intermediary crank arm (3) has become the crank arm (14) and the intermediary crankpin (4) has become the crankpin (13) of the crankshaft (12) .

2. A method according to claim 1, wherein the first positioning indicator (5) and the second positioning indicator (6) are aligned in axial direction of the intermediary crankshaft (1) .

3. A method according to claim 2, wherein the first positioning indicator (5) is applied by manufacturing a first recess in the intermediary crank arm (3) to such a depth that it ends at a location within the enveloping edge (7) of the intended intermediary crank arm hole (8), and the second positioning indicator (6) is applied by manufacturing a second recess in the intermediary crank pin (4), wherein the first and second recesses (5, 6) are located on the in- termediary crankshaft (1) such that after inserting the portion of the intermediary crankpin (4) into the intermediary crank arm hole (8), the first and second recesses (5, 6) can be aligned in a direction perpendicular to the centre line of the intermediary crankpin (4) .

4. A method according to claim 3, wherein the first and second recesses (5, 6) are formed by machining a continuous slit in the intermediary crank arm (3) and the intermediary crankpin (4) .

5. A method according to claim 4, wherein the slit (5, 6) extends over the entire length of the intermediary crank arm (3), as seen in axial direction of the intermediary crank shaft (1 ) .

6. A method according to claim 5, wherein the intermediary crank arm hole (8) is a through-hole, thus forming intermediary crank arm parts {10, 11) separated at the intermediary crank arm slit (5) after manufacturing the intermediary crank arm hole (8) .

7. A method according to claim 6, wherein the intermediary crank arm (3) and the intermediary crankpin (4) are fixed to each other by clamping the intermediary crank arm parts (10, 11) about the intermediary crankpin (4) .

8. A method according to one of the preceding claims, wherein the intermediary crank arm (3) and the intermediary crankpin (4) are separated by cutting the intermediary crankpin (4} at a joint portion (9) of the in- termediary crank arm (3} and the intermediary crankpin (4) .

9. A method according to one of the preceding claims, wherein the intermediary crankpin (4) is machined and adapted to fit in the intermediary crank arm hole (8) before inserting the intermediary crankpin (4) into the intermediary crank arm hole (8) .

10. A crankshaft (12) manufactured by the method according to one of the preceding claims.