KR100830065B1 - Crankshaft for v-type six-cylinder engine - Google Patents

Abstract

The crankshaft of the V-shaped six-cylinder engine includes first to sixth crank pins, first to fourth crank journals, and first to ninth arms that connect them to each other. Of the first to ninth arms, the excess weight portions (including the counterweight) of the third arm and the seventh arm are configured such that their centers are located in substantially opposite directions of the first crank pin and the sixth crank pin, respectively.

Description

Crankshaft of 6 type six cylinder engine {CRANKSHAFT FOR V-TYPE SIX-CYLINDER ENGINE}

1 is a right side view of the crankshaft 1 according to Embodiment 1 of the present invention,

2 is a plan view of the crankshaft 1 according to the first embodiment of the present invention,

3 is a perspective view of the crankshaft 1 according to the first embodiment of the present invention,

4 is a schematic diagram showing the positional relationship between the crank journals J1 to J4 and the crank pins P1 to P6 when the crankshaft 1 is viewed from the front,

5 is a cross-sectional view taken along the line V-V in FIG. 1,

6 is a cross-sectional view taken along the line VI-VI of FIG. 1,

FIG. 7 is a simplified balance diagram of FIG. 1;

8 is a simplified balance diagram of FIG. 2;

9 is a view of the balance diagrams of FIGS. 7 and 8 seen from the axial front;

10 is a graph showing the relationship between the direction in which the center G3 is located and the moment component in the 0 ° direction.

* Description of the symbols for the main parts of the drawings *

1: crankshaft

J1-J4: Crank Journal

A1-A9: cancer

P1-P6: Crank Pins

W1-W3, W7-W9: Counterweight

[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 8-121539

The present invention relates to a crankshaft of a V-type six cylinder engine.

Crankshafts used in V-shaped six-cylinder engines generally have six crank pins and four crank journals, and nine arms connecting them to each other.

Some of these arms are provided with counterweights for reducing the rotational inertia force generated in each arm and the unbalanced power generated in the crankshaft.

In the conventional crankshaft, this counter weight was located in the opposite direction of the crank pin connected to each arm with respect to the center axis line of the crankshaft. That is, it is the opposite direction of the crank pin for the arm which has only one crank pin connected, and the opposite direction of their midpoint for the arm which connects two crank pins.

Examples of such crankshafts are disclosed in Patent Document 1 described above. In addition, in this patent document 1, the 4th arm and the 6th arm have a structure which does not have a counterweight.

However, in the conventional crankshaft, there existed a problem that the reduction of the unbalanced power generated in a crankshaft is not fully made.

This is because the center of the counterweight is located in the opposite direction with respect to the position of the crank pin with respect to all of the arms on which the counterweight is provided.

This invention is made | formed in order to solve such a problem, and an object of this invention is to provide the crankshaft of a V-type 6 cylinder engine which can fully reduce the unbalanced power which arises.

Means to solve the problem

In order to solve the above-mentioned problem, the crankshaft of the V-cylinder engine which concerns on this invention is a 1st-4th crank journal in order from the front end to the rear end, and by them, the crankshaft is supported externally. The first to fourth crank journals supported by the members are provided coaxially with each other, and the central axis of the first to fourth crank journals is the central axis of the crankshaft, and the crankshaft is connected to an external connecting rod. The first to sixth crank pins are installed, the first crank pin and the second crank pin between the first crank journal and the second crank journal, and the third crank pin and the third crank journal between the second crank journal and the third crank journal. Four crank pins, between the third crank journal and the fourth crank journal, the fifth crank pin and the sixth crank pin are arranged in the order from the front end to the rear end, respectively, the first to fourth crank journal In the crankshaft provided between the 1st-6th crank pins, the 1st-9th arms which connect each other in order from front to back, 1st, 2nd, 8th, and 1st Nine arms have counter weights, fourth and sixth arms do not have counter weights, and third arms have counter weights, viewed from the axial direction of the crankshaft, projecting the central axis of the first crank pin and The straight line passing through the point which projected the center axis line of the crankshaft as the 3rd arm center straight line, the straight line passing the point which projected the center axis line of the 2nd crank pin, and the point which projected the center axis line of the crankshaft. The counterweight of a 3rd arm is included when it is set as the 1st straight line for 3rd arms, and makes the straight line which is symmetrical with the 1st straight line for 3rd arms with respect to the center straight line for 3rd arms as the 2nd straight line for 3rd arms. Surplus weight part The point which projected the core is located in the opposite side to the point which projected the center axis line of a 1st crank pin with respect to the 1st straight line for 3rd arms, and the center axis line of a 1st crank pin with respect to the 2nd straight line for 3rd arms. And the seventh arm has a counterweight, and the projection point of the central axis of the sixth crank pin and the projection point of the central axis of the crankshaft are viewed from the axial direction of the crankshaft. A straight line passing through is used as a center straight line for the seventh arm, and a straight line passing through the point on which the center axis line of the fifth crank pin is projected and the point on which the center axis line of the crank shaft is projected is the first straight line for the seventh arm, When the straight line symmetrical with the seventh straight line for the seventh arm is the second straight line for the seventh arm with respect to the center straight line for the seventh arm, the point projecting the center of the surplus weight portion including the counterweight of the seventh arm is On the first straight line for the seventh arm And, a sixth crank pin center axis point and located on the side opposite the projection a further, seventh, characterized in that with respect to Arms second straight line, the sixth position to the central axis a point opposite to the projection of the crankpin.

Implement the invention  Best form for

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on an accompanying drawing.

Embodiment 1.

1 to 3 show a crankshaft 1 according to the first embodiment. 1-3 are the right side view, top view, and perspective view of the crankshaft 1, respectively.

The crankshaft 1 is used for a V-shaped six-cylinder diesel engine having a bank angle of 60 °, four crank journals (first to fourth crank journals J1 to J4), six crank pins (first to one). Sixth crank pins P1 to P6), and nine arms (first to ninth arms A1 to A9).

The crank journals J1 to J4 are substantially cylindrical, and include a cylindrical portion including an axial center vicinity and a radius portion R formed to avoid stress concentration at both ends in contact with the arms A1 to A9. The crank journals J1 to J4 are spaced apart from each other in this order and arranged coaxially with each other. The central axis of these crank journals J1-J4 becomes the central axis of the crankshaft 1.

Here, in the axial direction, the crank journal J1 side is forward, and the crank journal J4 side is rearward. The crank journals J1 to J4 are supported by a cylinder block (not shown) via a journal bearing (not shown), whereby the crank shaft 1 is rotatably supported by a cylinder block which is a support member.

Between the crank journals J1 to J4, the crank pins P1 to P6 to which the connecting rod ends (not shown) are mounted are arranged in this order from the front end to the rear end. Crank pin (P1) and crank pin (P2) between crank journal (J1) and crank journal (J2), crank pin (P3) and crank pin (P4) between crank journal (J2) and crank journal (J3). This crank pin P5 and crank pin P6 are located between the crank journal J3 and the crank journal J4, respectively. The crank pins P1 to P6 are substantially cylindrical, and radial portions are formed at each end in the same manner as the crank journals J1 to J4.

4 shows the positional relationship between the crank journals J1 to J4 and the crank pins P1 to P6 when viewed from the axial front of the crank shaft 1. Each crank pin is offset by 60 degrees and is arrange | positioned in the order of crank pins P1, P2, P5, P6, P3, P4 in a circumferential direction.

Between each of the crank journals and each of the crank pins, arms A1 to A9 connecting them to each other are arranged in this order from the front end to the rear end. That is, the crank journal, the crank pin, and the arm crank journal J1, arm A1, crank pin P1, arm A2, crank pin P2, arm A3 from the front end to the rear end. , Crank Journal (J2), Arm (A4), Crank Pin (P3), Arm (A5), Crank Pin (P4), Arm (A6), Crank Journal (J3), Arm (A7), Crank Pin (P5) , Arm A8, crank pin P6, arm A9, crank journal J4 in this order.

Among the arms, the counter weights W1 to W3 and the counter weights W7 to W3 for reducing the rotational inertia force generated on each arm and the imbalanced power generated on the crankshaft, respectively, in the arms A1 to A3 and the arms A7 to A9. W9) is formed. The counter weight is not formed in the remaining arms, that is, the arms A4 to A6.

The shape of the arm A3 is shown in FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 1. The arm A3 reduces the connecting portion A3a connecting the crank pins P2 and the crank journal J2, the outer edge portion A3b surrounding the outer edge of the connecting portion A3a, the rotational inertia force and the imbalanced force. A counter weight W3 to make it work. Among these, the area which combined the outer edge part A3b and the counterweight W3 is made into the surplus weight part X3.

Hereinafter, the definitions of the connecting portion A3a and the excess weight portion X3 are shown.

5, the circle P2 'which projected the outer periphery of the crank pin P2, and the circle P2' which projected the outer periphery of the crank journal J2 are shown. The circles P2 'and the circle J2' are not cylindrical portions R at both ends of the crank pins P2 and the crank journal J2, but are rotatably fitted with connecting rods or journal bearings. The outer periphery of the part forming this is projected.

The point which projected the center axis line of the crank pin P2 (that is, the center of the circle P2 ') as the point OP2, and the point which projected the center axis line of the crankshaft 1 (that is, the circle 2') Center) is made into the point OJ, and the straight line which passes the point OP2 and the point OJ is made into the straight line c which is the 1st straight line for 3rd arms. Let the common tangent of the circle P2 'and the circle J2' be (t1 and t2). (When three or more common tangents exist, only the tangent which passes through the same contact point in both circles with respect to the straight line c). Consider). The area defined by the circle P2 'and the circle J2' and their common tangent t1 and t2 is the connection part A3a.

As described above, the connecting portion A3a is defined, and a portion other than the connecting portion A3a of the arm A3 is defined as the excess weight portion X3. The center of this excess weight part X3 is shown in FIG. 5 as center G3.

From the arm A5 located in the center of the crankshaft 1, the point where the center axis line of the crank pin at the outermost side of the arm A3 side, that is, the crank pin P1 (not shown in FIG. 5) is projected is shown. Let it be the point OP1. When the straight line passing through this point OP1 and the point OJ is the straight line v which is the 3rd arm center straight line, the center G3 will be located on the straight line v, and the point (about the point OJ) OP1) is the opposite side. That is, the center G3 is in the direction opposite to the crank pin P1 with respect to the center axis of the crankshaft 1.

The shape of the arm A7 is shown in FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 1. The arm A7 includes the excess weight portion X7 in which the coupling portion A7a, the outer edge portion A7b and the counterweight W7 are combined in the same manner as the arm A3.

The excess weight part X7 is defined similarly to the excess weight part X3 in arm A3. That is, the connection part A7a with respect to the circle P5 'which projected the center axis line of the crank pin P5 (center is a point OP5), and the circle J3' which projected the outer periphery of the crank journal J3. ) Is defined, and the portion excluding the connecting portion A7a from the arm A7 becomes the excess weight portion X7.

The center G7 of the surplus-weight part X7 is the point OP6 which projected the center axis line of the crank pin P6 (not shown in FIG. 6), and the point which projected the center axis line of the crankshaft 1 (that is, It is located on a straight line passing through the point OJ, which is the center of the circle J3 ', and is opposite to the point OP6 with respect to the point OJ.

The shapes of the arms A1, A2, A8 and A9 may be well known, but for example, in the present embodiment, as shown in Figs. 1 to 3, the center of the surplus weight portion including the respective counterweights is Each is configured to be positioned in an optimal direction to reduce the imbalance force.

In arm A1, the center of the surplus-weight part of arm A1 (not shown. It is defined similarly to arms A3 and A7) is the point which projected the center axis line of crankshaft 1, and the crank pin. It is located on a straight line passing through the point on which the center axis line of P1 is projected, and is opposite to the center of the crank pin P1 with respect to the point on which the center axis line of the crank shaft 1 is projected.

In arm A2, the center of the surplus-weight part of arm A2 (not shown. It is defined similarly to arms A3 and A7) is the point which projected the center axis line of crankshaft 1, and the crank pin. It is located on a straight line passing through the point on which the center axis line of P1 is projected, and is opposite to the center of the crank pin P1 with respect to the point on which the center axis line of the crank shaft 1 is projected.

Regarding the cancers A8 and A9, they are the same as the cancers A2 and A1, respectively.

7-9, the balance state containing the total weight and center position of each arm is shown.

FIG. 7 simplifies FIG. 1 and is a balance diagram in which each arm represents a balance of the weight of the entire arm (including the connecting portion and the excess weight portion) with respect to the arms A1 to A3 and A7 to A9. The position of the center of the circle indicates the position of the entire center of the arm. Also, since the arms A4 to A6 do not have counter weights, circles do not appear.

FIG. 8 is a balance diagram similarly to FIG. 2, and FIG. 9 is a view of the balance diagrams of FIGS. 7 and 8 from the axial front.

In addition, the circle | round | yen shown in these FIGS. 7-9 shows the balance of the whole arm as mentioned above, and does not show the balance of a counter weight only and the balance of only a surplus weight part. For example, with respect to arm A3, the circle which shows the whole center in FIGS. 7-9 has the center containing both the connection part A3a and the excess weight part X3 in FIG. It is in the position different from the center G3 of only the excess weight part X3.

With respect to the arms A1 to A3 and A7 to A9, the weight of the entire arm satisfies the relationship A1 = A9> A2 = A8> A3 = A7. The distance between the central axis of the crankshaft 1 and the entire center of the arm also satisfies the relationship A1 = A9> A2 = A8> A3 = A7.

In FIG. 9, the arm A1 and the arm A9 are opposite directions to each other in the direction of the center of the arm as viewed from the center axis of the crankshaft 1. In addition, with respect to the straight line passing through the centers of the arms A1 and A9, all the centers of the arms A2, A3, A7 and A8 are all on the same side as the centers of the crank pins P2 and P5. have. Moreover, with respect to the straight line (shown by the dashed-dotted line in FIG. 9) orthogonal to the straight line which passes through the center of arm A1 and the arm A9, and intersects with the central axis of the crankshaft 1, arm A1, The entire center of A2, A3 is on the same side as the center of the crank pins P3, P5, P6, and the entire center of the arms A7, A8, A9 is on the opposite side, namely the crank pins P1, P2, P4. It is on the same side as the center of.

Next, the action of the crankshaft 1, each arm, and each counterweight comprised as mentioned above is demonstrated.

When the engine is operated, the small end of the connecting rod connected to the piston reciprocates, whereby the crank pins P1 to P6 connected to the connecting rod far end rotate around the center axis of the crankshaft 1. At this time, the rotational inertia force due to the weight of the rotating part including the crank pins P1 to P6 and the connecting rod large ends acts, and a bearing load is generated between the crank journals J1 to J4 and the journal bearings supporting the respective ones.

The counterweights W1 to W3 and W7 to W9 respectively have the center of the surplus weight portion in the corresponding arm in the direction opposite or approximately to the crank pin connected to each arm with respect to the center axis of the crankshaft 1. Since it is comprised so that it may be located in the opposite direction, this rotational inertia force is reduced. Thereby, the bearing load which generate | occur | produces in the crank journal J1-J4 is reduced.

In addition, an unbalanced force of rotation primary components is generated by the reciprocating part weight including the piston and the connecting rod small end and the weight of the rotating part including the crank pins P1 to P6 and the connecting rod big end. This causes a so-called precession movement to the crankshaft 1.

The counterweights W1 to W3 respectively position the center of the surplus weight portion in the corresponding arm in a direction opposite to or approximately opposite to the crank pin P1 with respect to the center axis of the crankshaft 1. Consists of. Similarly, the counterweights W7 to W9 respectively move the center of the surplus weight portion in the corresponding arm in the opposite or substantially opposite direction to the crank pin P6 with respect to the central axis of the crankshaft 1. It is configured to locate.

By such a configuration, the unbalanced power generated in the crankshaft 1 is reduced.

In this way, in the crankshaft 1 of the V-type six-cylinder diesel engine according to the first embodiment, the center of the surplus-weight portion X3 of the arm A3 is cranked with respect to the center axis of the crankshaft 1. It is in the opposite direction of the pin P1. In addition, also about arm A7, the center of surplus-weight part X7 exists in the opposite direction of crank pin P6.

By this structure, the unbalanced force generated in the crankshaft 1 by the crank pins P1 and P6 can be reduced efficiently.

Moreover, in the conventional crankshaft, the counter weight of the arm corresponded to arm A4 and A6 is installed in the substantially opposite direction of the crank pin (corresponding to (P3 and P4) in FIG. 4, respectively) connected. do. As shown in FIG. 4, these were in the direction which increases the unbalanced power of the crankshaft produced by the outermost crank pin (corresponding to (P1 and P6) in FIG. 4), respectively.

On the other hand, in the crankshaft 1 in Embodiment 1, since the arms A4 and A6 do not have a counterweight, the unbalanced force of the crankshaft 1 is not increased. That is, compared with the conventional crankshaft, the imbalanced power can be reduced.

In addition, in Embodiment 1 mentioned above, although the bank angle of an engine is 60 degrees, this may be around 60 degrees, and 45 degrees or 72 degrees may be sufficient as it. Moreover, as long as it is an angle larger than 0 and less than 90 degrees, a different angle may be sufficient. That is, the angle between the series V type and the 90 ° V type may be sufficient.

In Embodiment 1 mentioned above, the center G3 of the surplus-weight part X3 of the arm A3 is a direction opposite to the point OP1 with respect to the center axis of the crankshaft 1, ie, the straight line v. Although it is in a phase, this may be a direction of a predetermined range, even if it is not a straight line v phase.

This predetermined range is demonstrated using FIG. A straight line symmetrical with the straight line c with respect to the straight line v is a straight line c1 which is the second straight line for the third arm. The center G3 is on the opposite side to the point OP1 on which the center axis line of the crank pin P1 is projected with respect to the straight line c, and also on the opposite side to the point OP1 with respect to the straight line c1. . That is, in FIG. 5, it is located in the direction of the range shown by (alpha). In the configuration in which the center G3 is in this range, compared with the configuration in which the center G3 is on the straight line c or on the c1, the center G3 is the point O1 with respect to the point OJ. Since it approaches by the opposite direction, the unbalanced force of the crank journal 1 can be reduced more efficiently.

In addition, the direction of this predetermined range has both sides when the direction opposite to the point OP1 is 0 degree with respect to the range of 50 degrees back and forth, ie, the point OJ, centering on the straight line V. The direction of each 50 degree range may be sufficient. This is the direction of the range shown by (beta) in FIG.

The graph of FIG. 10 shows the direction of the center G3 on the X-axis, and shows the ratio of the direction component of 0 degrees among the moment which the excess weight part X3 generate | occur | produces on a Y-axis as a percentage. According to this graph, the moment component decreases relatively nonlinearly until the direction of the center G3 reaches 50 °, but rapidly decreases almost linearly when it exceeds 50 °. Since the moment component in the 0 ° direction is to reduce the unbalanced right force of the crankshaft 1, the larger this can effectively reduce the unbalanced force.

Therefore, from the graph of FIG. 10, when the opposite direction to the point OP1 is 0 degree with respect to the point OJ, if the center G3 is located in the direction of the range of 50 degrees of both sides, a crankshaft It can be said that the imbalanced right of (1) can be reduced more efficiently.

Although the description regarding said predetermined range is description regarding arm A3, this is the same also about arm A7. However, arm A3 is at arm A7, surplus weight portion X3 is at surplus weight portion X7, center G3 is at center G7, point OP1 at point OP6, The point OP2 corresponds to the point OP5, respectively. Based on this correspondence, the seventh straight line for the seventh arm, the first straight line for the seventh arm, and the seventh arm agent respectively correspond to the third straight line for the third arm, the first straight line for the third arm, and the second straight line for the third arm. 2 straight lines are defined.

Embodiment 2

The crankshaft 2 which concerns on Embodiment 2 is set as the structure in which the arm A5 has the counterweight W5 in the crankshaft 1 which concerns on Embodiment 1. As shown in FIG.

The counterweight W5 is provided in the opposite direction of the crank pins P3 and P4 with respect to the central axis of the crankshaft 1 as described below.

The arm A5 includes a connecting portion A5a for connecting the crank pins P3 and P4 defined in the same manner as the arms A3 and A7, and an outer edge portion A5b surrounding the outer edge of the connecting portion A5a. And a counter weight W5 for reducing the rotational inertia force. Among these, similarly to arms A3 and A7, the area which combined the outer edge part A5b and the counterweight W5 is made into the excess weight part X5. Furthermore, let the center G5 be the center of the weight part X5 of the surplus weight part X5.

In the axial cross section of the crankshaft 1, the point at which the center G5 is projected is the two at which the center axis of each of the crank pins P3 and P4 is projected with respect to the center axis of the crankshaft 1. It is in the opposite direction of the center of the point. In other words, the point at which the center G5 is projected is positioned substantially in the opposite direction to any of the points at which the crank pins P3 and P4 to which the arm A5 is connected are projected.

Thus, in the crankshaft 2 which concerns on Embodiment 2, since the arm A5 has the counterweight W5, the rotational inertia force which crank pins P3 and P4 generate | occur | produce is reduced, thereby Bearing loads generated in the journals J2 and J3 can be reduced.

According to the present invention, a crankshaft of a V-shaped six-cylinder engine capable of sufficiently reducing an unbalanced force can be provided.

Claims (4)

As a crankshaft of a V-cylinder engine containing a crank journal, a crank pin, an arm, A first to fourth crank journal provided in the order from the front end to the rear end, wherein the crank shaft is supported by an external support member by the first to fourth crank journals, and the first to fourth crank journals , The first to fourth crank journals which are provided coaxially with each other and the central axis of the first to fourth crank journals is the central axis of the crankshaft; First to sixth crank pins connected to an external connecting rod, wherein between the first crank journal and the second crank journal, the first crank pin and the second crank pin, the second crank journal and the third Between the crank journal, the third crank pin and the fourth crank pin, between the third crank journal and the fourth crank journal, the fifth crank pin and the sixth crank pin, respectively, from the front end to the rear end First to sixth crank pins arranged in sequence; The first to fourth crank journals and the first to sixth crank pins are connected to each other, and the first to fourth crank journals and the first to sixth crank pins are provided in an order from front to rear ends. Including first to ninth cancers; The first, second, eighth and ninth arms have counter weights, the fourth and sixth arms do not have counter weights, The third arm has a counter weight, Viewed from the axial direction of the crankshaft, A straight line passing through the point projecting the center axis line of the first crank pin and the point projecting the center axis line of the crankshaft is regarded as a third arm center straight line, A straight line passing through the point projecting the center axis line of the second crank pin and the point projecting the center axis line of the crankshaft is regarded as the first straight line for the third arm, When the straight line which is symmetrical with the said 1st straight line for 3rd arms with respect to the said 3rd arm center straight line is made into the 2nd straight line for 3rd arms, The point which projected the center of the surplus weight part containing the said counter weight of the said 3rd arm is located in the opposite side to the point which projected the center axis line of the 1st crank pin with respect to the 1st straight line for 3rd arms, and , With respect to the second straight line for the third arm, is located on the side opposite to the point where the central axis of the first crank pin is projected, The seventh arm has a counter weight, Viewed from the axial direction of the crankshaft, A straight line passing through the point projecting the center axis line of the sixth crank pin and the point projecting the center axis line of the crank shaft is regarded as the seventh arm center straight line, A straight line passing through the point projecting the center axis line of the fifth crank pin and the point projecting the center axis line of the crankshaft is used as the first straight line for the seventh arm. Regarding the center straight line for the seventh arm, when the straight line symmetrical with the first straight line for the seventh arm is the second straight line for the seventh arm, The point which projected the center of the surplus weight part containing the said counterweight of the said 7th arm is located in the opposite side to the point which projected the center axis line of the 6th crank pin with respect to the 1st straight line for 7th arms, With respect to the second straight line for the seventh arm, located on the side opposite to the point projecting the center axis line of the sixth crank pin, The fifth arm is a crank shaft of a V-shaped six-cylinder engine having a counterweight for reducing the rotational inertia force. delete The method of claim 1, Viewed from the axial direction of the crankshaft, The point which projected the center of the surplus-weight part containing the said counterweight of the said 3rd arm is on the said 3rd arm center straight line, The point which projected the center of the surplus weight part containing the said counterweight of the said 7th arm is a crankshaft of the V-shaped 6-cylinder engine on the said center straight line for the 7th arm. The method of claim 1, Viewed from the axial direction of the crankshaft, The point which projected the center of the said excess weight part of a said 3rd arm is a direction opposite to the point which projected the center axis line of the said 1 crank pin on the basis of the point which projected the center axis line of the said crankshaft. It is located in the direction of the range of 50 degrees each on both sides to center, The point which projected the center of the said excess weight part of the said 7th arm was centered in the direction opposite to the point which projected the center axis line of the 6th crank pin on the basis of the point which projected the center axis line of the said crankshaft. The crankshaft of the V-shaped six-cylinder engine located in the direction of 50 degrees each on both sides.

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