JP2998058B2 - V-type 6-cylinder engine crankshaft and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft for a V-6 engine.

[0002]

2. Description of the Related Art A general structure of a crankshaft 1 used in a V-type six-cylinder engine is as shown in FIG. 1, and four journals J1 to J4 supported on a cylinder block via bearings are formed by shafts. The front ends are arranged at substantially equal intervals from the front to the rear of the engine. Further, pins P1 to P6 connected to the pistons of the cylinders by connecting rods are connected between the journals J1 to J4 respectively.
A total of six pins are provided, each of which is spaced apart from each other by 60 degrees about the central axis in a plane perpendicular to the rotational central axis of the crankshaft. Furthermore,
Nine arms A1 to A9 connecting between each of these journals and each pin and between each of the pins are arranged,
Each arm is provided with a counterweight for canceling a unique shaking motion peculiar to the crankshaft of the V-6 engine.

[0003] The method of manufacturing the crankshaft will be described. The crankshaft 1 has a complicated shape as described above, so that when the material is manufactured by forging, it is difficult to remove the die in the finished shape. It is conceivable that the shaft is forged in a shape that can be easily removed from the mold, and then manufactured by the twist method described below. That is, after the material of the shaft is subjected to forging by applying a pressure with a forging die (not shown), as shown in FIGS. 6 and 7, the first and second journals J1 and J2 are separated by the first twisting die 6 using the second twisting die 6. The fixed journal 7 between the third journals J2 and J3
The fourth journals J3 and J4 are gripped by the second twist type 8 respectively, and then the first twist type 6
Is rotated clockwise as viewed from the front end of the shaft 1 and the second twist type 8 is rotated counterclockwise by 60 degrees.
The third journals J2 and J3 are twisted to obtain a completed shape.

FIGS. 7A and 7B show a state in which the third arm A3 is gripped by the first twist type 6. FIG. 1st for shaft 1
When the gripping direction of the twist die 6 before the above-described die rotation (the direction of the arrow 12) is indicated by arrows 10 and 11 in FIG. 7A, the die removing directions after the die rotation are indicated by arrows 13 and 14 in FIG. The vertical direction is the same as the above arrows 10 and 11 due to the mechanism of the actuator. Reference numeral 9 denotes a space necessary for preventing the twist type and the arm from interfering with each other at the time of the die cutting.

[0005] Various improvements have been attempted on the crankshaft to reduce the overall weight and improve the balance. However, these improvements must be made with due consideration given to compatibility with the above-described method. Next, this point will be described.

As a crankshaft, a nine-weight crankshaft in which counterweights are provided on all nine arms is generally used. However, since the total weight is extremely large, it is disclosed in Japanese Utility Model Publication No. 2-20517. As described above, it has been proposed that the weight of the crankshaft is reduced as much as possible by making the nine counterweights the minimum weight. However, since it was 9 weights, the overall weight remained large.

[0007] Therefore, as disclosed in Japanese Utility Model Publication No. 3-4850, a seven-weight crankshaft having seven counterweights in which the third and seventh arms from the front end of the shaft have no counterweight is provided. −
No. 70500, third and fourth from the front end of the shaft
There has been proposed a five-weight crankshaft having five counterweights in which the fifth, sixth, and seventh arms have no counterweight.

However, although the crankshaft having the seven or five counterweights has a reduced overall weight as compared with a crankshaft having nine counterweights,
When this is manufactured by the twist method, the following problem occurs.

That is, since these crankshafts are not provided with a counterweight on the third and seventh arms A3 and A7, for example, the relationship between the third arm A3 and the first twist mold 6 is described in FIG. It becomes like b.
Although the torsion is applied to the second journal J2, a torsional force is also applied to the third arm A3 close to the second journal J2, but the third arm A3 has no counterweight and therefore has a simple shape close to a circle. Since the first twist mold 6 has a small portion to be caught, the holding force of the mold 6 is reduced, and slippage between the two is likely to occur during rotation. Therefore, the torsion is not sufficiently imparted, or the torsion is generated in a portion other than the second journal J2 which does not originally generate the torsion, thereby deteriorating the accuracy of the shaft shape after the twisting method. Further, there has been a problem that a defect is likely to occur during subsequent processing or balance correction.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made to reduce the overall weight of an engine crankshaft, improve the holding performance of an arm during twisting, and improve the shape accuracy during twisting. It is an object of the present invention to provide an improved crankshaft for a V6 engine.

[0011]

According to a first aspect of the present invention, there is provided a crankshaft of a V-type six-cylinder engine comprising four journals, six pins, and nine arms. 1, 2, 3, 5, 7, 8,
A counterweight is provided only on the ninth arm.

A second aspect of the present invention is characterized in that the third counterweight and the fifth counterweight of the first aspect are formed in a sector shape which spreads toward the tip.

According to a third aspect of the present invention, the first and ninth arms from the front end of the crankshaft according to the first and second aspects are balanced with each other as viewed from the axial direction, and the second to eighth arms are the same. The arms are also balanced with each other. According to a fourth aspect of the present invention, there is provided a counterweight for an arm having an enlarged diameter portion, wherein the enlarged diameter portion forming a contact surface with a thrust plate is formed on one of the third arm and the seventh arm. Is reduced in size so that the second to eighth arms are mutually balanced.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a crankshaft of a V-type six-cylinder engine having a part of a counterweight, wherein a forged portion for giving a predetermined relative phase difference between the respective pins between the respective journals. Later, the arm without the weight is gripped with a fixed type, the outer arm of the arm without the weight is gripped with two twist types, and each twist type is rotated in the opposite direction to the fixed type. The twist is added to the shaft by a twisting method.

[0015]

The present invention is a seven-weight crankshaft of a V-type six-cylinder engine in which the counterweights of the fourth and sixth arms are eliminated, so that the overall weight can be reduced and the weight can be reduced. The nine arms are mutually balanced, and the second to eighth arms are mutually balanced, so that the entire arm including the counterweight can be balanced. According to the present invention, the counterweight of one of the third arm or the seventh arm having the enlarged diameter portion serving as the contact surface of the thrust plate is the third arm.
By being formed smaller than the counter weight of the arm or the other arm of the seventh arm, the balance is achieved in the axial direction of the crankshaft. Further, since the present invention is a seven-weight crankshaft of a V-type six-cylinder engine in which the counterweights of the fourth and sixth arms are eliminated, at least the third arm gripped by the first twist type and the second twist At least a seventh arm gripped by the mold is provided with a counter weight, and when the first and second twist molds are rotated in opposite directions to each other with respect to the fixed mold, they are securely twisted by the second and third journals. Can be processed. Further, the fourth and sixth arms gripped by the fixed mold do not have a counter weight, but the fixed mold does not rotate, so the space does not exist, and therefore, the holding of the fixed, fourth, fifth, and sixth arms with respect to the fourth, fifth, and sixth arms Power is secured enough.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an entire crankshaft according to the present invention.

The shaft 1 has a shaft 4 for rotatably supported by a cylinder block of the engine via a bearing.
The journals J1 to J4 are arranged at substantially equal intervals from the front end to the rear end of the shaft. Pins P1 to P1 for rotatably supporting a base end of a connecting rod connected to a piston of each cylinder are provided between the journals.
6 are arranged two by two, and these pins are arranged at intervals of 60 degrees about the center axis in a plane perpendicular to the rotation center axis of the crankshaft. Further, arms A1 to A9 are arranged between each journal and each pin and between each pin and each pin.

Of the nine arms, the first, second, third, fifth, seventh, eighth, and ninth arms are 1, 2, 3, 5, 7, 8, and 9 from the front end of the shaft. A1, A2, A3,
A5, A7, A8, and A9 are respectively provided with counterweights W1 to W7 for canceling the squirting motion, but the fourth and sixth fourth and sixth arms A4 and A6 are provided.
Has no counterweight. Each of the counterweights has a fan shape that expands toward the tip.

Each counter weight has a different mass, and the counter weights W of the first and ninth arms at both ends are different.
1, W7 has the largest mass. Next, the counter weights W2, W4, W6 of the central arm between the journals have a large mass, and the remaining two counter weights W3, W
5 is the minimum mass, but the fourth and sixth arms A4, A
6 does not have a counterweight, so it is lighter.

Therefore, each of the above counter weights W1 to W7
The relationship of the mass of the following equation is W1 ≒ W7> W2 ≒ W4 ≒ W6> W
It is expressed by 3 ≒ W5.

As shown in FIGS. 2A to 2F, 3A to 3C, and FIG. 4, when the crankshaft 1 is viewed in the axial direction, when the first pin P1 is at the upper position,
The counterweight W1 is disposed at a lower position with respect to the shaft center, and the seventh counterweight W7 is disposed at a higher position with respect to the shaft center.
The arm and the ninth arm are mutually balanced when viewed from the axial direction. Further, with respect to the center of the crankshaft, the second counter weight W2 is equal to the first and second pins P
1, P2 and the third counter weight W3 are equal to the second pin P2,
The fourth counter weight W4 is equal to the third and fourth pins P3,
P4, the fifth counter weight W2 is the fifth pin P5, the sixth
The counter weight W6 is equal to the fifth and sixth pins P5 and P6.
, Respectively, are disposed on substantially opposite sides.

As shown in FIG. 5, the sixth and seventh arms A6 and A7 sandwiching the third journal J3 are formed with a diameter-enlarging portion 5 which protrudes in a circular shape around the journal. Further, a separate thrust plate 3 is interposed between the enlarged diameter portion 5 and the cylinder block 2 so as to be slidable with respect to the enlarged diameter portion 5. The thrust plate 3 positions the front and rear of the crankshaft 1 with respect to the longitudinal direction of the cylinder block, and is supported by the enlarged diameter portion. Also,
The thrust plate 3 is fixed to the cylinder block and the bearing cap separately along the outer periphery of the enlarged diameter portion 5 in two semicircular arc-shaped portions on the cylinder block side and the bearing cap side (not shown). Reference numeral 4 denotes a metal for the above-mentioned bearing.

Since the seventh arm A7 has the enlarged diameter portion 5,
The counter weight W5 of the seventh arm A7 is the third arm A
3 is slightly smaller than the counter weight W3. By doing so, the second to eighth arms A2 to A
8 are mutually balanced.

The thrust plate 3 may be provided on one of the second journal J2 and the third journal J3, and may be the second journal J2. When provided on the second journal J2, the third and fourth arms A3,
A4 has an enlarged diameter portion 5, and the counterweight W3 of the third arm A3 is equal to the counterweight W5 of the seventh arm A7.
It is formed slightly smaller than.

Next, a manufacturing method according to the present invention will be described.

FIG. 6 shows a conceptual diagram of the manufacturing method according to the present invention.

Crankshaft 1 of V-type 6-cylinder engine
When forming a material by forging, it is difficult to forge with a finished shape due to the limitation of the forging direction of the forging die. , Between the fourth journal and the second and third journals, twisted in the opposite direction by 60 degrees to produce a completed shape.

First, the material of the crankshaft is forged by applying pressure with a forging die (not shown). Then, as shown in FIG. 6, the forged crankshaft 1 is connected to the first to third arms A1 to A3 by a first twist mold 6 to form fourth to sixth arms.
The arms A4 to A6 are fixed dies 7, and the seventh to ninth arms A7
To A9 are held by the second twist mold 8. Then fixed mold 7
To the first twist type 6, the first to third arms A1 to
The counterweights W1 to W3 provided on the A3 are used as gripping portions, and are rotated clockwise by 60 degrees as viewed from the front end of the crankshaft. The second and third journals J2 and J3 are manufactured by rotating the counterclockwise rotation of 60 degrees counterclockwise using W5 to W7 as gripping portions.

For example, in the third arm, as shown in FIG. 8A, the third arm is vertically moved by the first twist type 6 (arrow 1).
0, 11), and then rotated 60 degrees clockwise (arrow 12) with respect to the fixed mold 7 as viewed from the front end of the shaft. Thereafter, as shown in FIG. 8B, the first twist mold 6 is pulled out in the same direction as that at the time of holding, that is, in the vertical direction (arrows 13 and 14). At this time, since the first twist type 6 and the third arm A3 interfere with each other, a space 9 is provided between the twist type and the arm.

When the two twist molds 6 and 8 rotate, FIG.
As shown in a and b, for example, in the third arm A3, 15;
The force from the mold 6 is applied to the portion 16 to rotate. The fan-shaped counterweight W3 effectively receives this force and acts effectively to surely rotate the arm A3.
This effect of the sector weight W3 is evident when compared to the example of FIGS. 7a, b without said weight W3.
In the case of b, since the point of action of the force acting on the arm is small, slipping easily occurs between the twist type and the arm, and reliable rotation of the arm is not guaranteed.

The shape of the counterweight may be all sector-shaped as in this embodiment, but at least the third and seventh arms A3, which receive a strong torsional force at the time of mold rotation.
A7, that is, only the innermost arm of the arms gripped by the twist type may have a fan shape.

[0033]

As described above, according to the crankshaft according to the present invention, the weight of the entire shaft can be reduced, the responsiveness in the transition period of the engine can be improved, and the shape accuracy at the time of manufacturing can be ensured, resulting in defective manufacturing. Decrease.

According to the shaft of the second aspect, the shape accuracy at the time of manufacturing the shaft can be further improved, and according to the shaft of the third aspect, the balance viewed from the axial direction can be secured, and the processing after the twisting method, the balance correction, etc. And the shape accuracy can be further improved. Further, according to the shaft of the fourth aspect, since the thrust plate is provided and the balance in the axial direction is secured, it is particularly effective in practical use.

Further, according to the manufacturing method of the fifth aspect, it is possible to improve the shape accuracy at the time of manufacturing a crankshaft not having a part of the counterweight, such as a seven-weight crankshaft, and to reduce defective manufacturing.

[0036]

[Brief description of the drawings]

FIG. 1 is a side view of a crankshaft according to the present invention.

FIG. 2 is a cross-sectional view based on each line of arrow in FIG. 1,
2A is a sectional view taken along line II, FIG. 2B is a sectional view taken along line II = II, FIG. 2C is a sectional view taken along line III-III, and FIG.
FIG. 2e is a sectional view taken along the line VV, FIG.
-VI line sectional view

FIG. 3 is a cross-sectional view based on each line of arrow in FIG. 1,
3A is a sectional view taken along line VII-VII, and FIG.
VIII line sectional view, FIG. 3c is IX-IX line sectional view

FIG. 4 is a schematic view showing the balance of each arm in the crankshaft axial direction according to the present invention.

FIG. 5 is a partially enlarged view of a third journal in FIG. 1;

FIG. 6 is a conceptual diagram of a crankshaft twisting method according to the present invention.

FIG. 7 is a cross-sectional view showing a gripping state of the third arm before and after the twist type rotation in the related art, FIG. 7a shows a gripping state of the third arm before the twist type rotation, and FIG.
6 shows a gripping state of the third arm after the twist type rotation.

FIG. 8 is a cross-sectional view showing a gripping state of a third arm before and after the twist type rotation in the embodiment of the present invention, and FIG.
FIG. 8 shows a gripping state of the third arm before the twist type rotation.
b shows the gripping state after the twist type rotation of the third arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine crankshaft 6 1st twist type 7 Fixed type 8 2nd twist type J1-J4 1st-4th journal P1-P6 1st-6th pin A1-A9 1st-9th arm W1-W7 1st 7th counter weight

Continued on front page (72) Inventor Toshikazu Kanai 5-33-8 Shiba, Minato-ku, Tokyo Examiner, Mitsubishi Motors Corporation Co., Ltd. Haruhiko Kubota (56) References JP-A-59-212555 (JP, A) JP-A-60-4645 (JP, A) JP-A-5-192734 (JP, A) JP-A-59-177848 (JP, U) U.S. Pat. No. 2,632,340 (US, A) (58) Fields investigated (Int. . ^7, DB name) F16F 15/26 B21K 1/08

Claims (5)

(57) [Claims] 1. A first to a fourth order from a front end to a rear end.
Journals are provided, first and second pins are provided between the first and second journals, third and fourth pins are provided between the second and third journals, and fifth and fifth pins are provided between the third and fourth journals. 6
A pin is provided, and the crankshaft of the V-type six-cylinder engine is further connected between the journals and the pins and between the pins and the pins in order by first to ninth arms. The first, second,
Only the third, fifth, seventh, eighth, and ninth arms have the first to seventh arms.
A crankshaft for a V-type six-cylinder engine, wherein counterweights are respectively provided. 2. The V-type 6 according to claim 1, wherein said third counter weight and said fifth counter weight have a fan-shaped shape extending toward the tip.
Crankshaft for cylinder engine. 3. When the first pin is higher than the center of the crankshaft, the first and seventh counter weights are positioned lower and higher, respectively, and the second counter weight is shifted between the first and second pins and the second pin. The third counter weight is the second pin, the fourth counter weight is the third and fourth pins, and the fifth
The counter weight is located on the fifth pin and the sixth counter weight is located on substantially the opposite side of the fifth and sixth pins, respectively. The first and seventh counter weights have the maximum mass and the first weight is viewed from the axial direction. The arm and the ninth arm are mutually balanced, the second, fourth, and sixth counterweights have the next largest masses after the first and seventh counterweights, and the third and fifth counterweights have 3. A crankshaft for a V-type six-cylinder engine according to claim 1, wherein the crankshaft has the smallest mass and is mutually balanced by the second to eighth arms. 4. An enlarged diameter portion forming an abutting surface with the thrust plate is provided on both arms adjacent to one of the second and third journals on which a thrust plate is disposed. The counterweight of one of the third arm or the seventh arm provided with the enlarged-diameter portion is formed smaller than the counterweight of the other arm. The crankshaft of the V-type 6-cylinder engine described in the paragraph. 5. A first to a fourth journal are sequentially provided from a front end to a rear end, and first and second pins are provided between the first and second journals, and first and second journals are provided between the second and third journals. The third and fourth pins are provided with fifth and sixth pins between the third and fourth journals.
And each pin is connected by a first to a ninth arm, and the counter weights are respectively provided only to seven of the arms except for the fourth and sixth arms located between the second and third journals. A method for manufacturing a crankshaft of a V-type six-cylinder engine, wherein the first pin and the second pin are arranged and arranged so that each pin has a set relative phase difference around an axis. The relative phase difference, the relative phase difference between the third pin and the fourth pin, and the relative phase difference between the fifth pin and the sixth pin are each set to a predetermined relative phase difference by forging from the material. A step of integrally molding a journal, an arm, and a pin; holding at least a fourth arm and a sixth arm with a fixed type, at least a third arm with a first twist type, and holding at least a seventh arm with a second twist type; By rotating each twist type in the opposite direction to the fixed type, a twist is applied to the second journal and the third journal, and the relative phase difference between the second pin and the third pin and the fourth pin and the Matching the relative phase between the five pins with a predetermined relative phase difference. 6. A method for manufacturing a crankshaft for a V-type six-cylinder engine.