JP2017129189A - engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine which enables reduction of flexural vibration of a crank shaft while reducing the weight of the crank shaft.SOLUTION: An engine 1 includes: a crank pulley 21 including a rim part 22 having an annular shape, a hub part 23 located at a center of the rim part 22, and a connection part 24 connecting the hub part 23 with the rim part 22 and in which a transmission belt BLT is wound around the rim part 22; and a crank shaft 11 including a crank journal 12, which is pivotally supported so as to rotate around an axis, and a crank arm 14 extending from the crank journal 12 in a radial direction, the crank shaft 11 having one end to which the hub part 23 is fixed. Reinforcement ribs 25 connecting the hub part 23 with the rim part 22 are erected at the connection part 24 along an extension direction of the crank arm 14 located adjacent to the crank pulley 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine including a crankshaft having a crank pulley attached to a shaft end.

In an automobile engine, a piston disposed in a cylinder so as to be able to reciprocate is connected to a crankshaft via a connecting rod. The crankshaft is pivotally supported around an axis, and a crank pulley is attached to one end thereof.
The reciprocating motion of the piston is converted into rotational motion by the crankshaft, and the rotational force of the engine is transmitted to various auxiliary machines via a transmission belt wound around the outer periphery of the crank pulley.
Regarding a pulley constituting such an engine, Patent Document 1 discloses a configuration aiming to improve heat dissipation.

JP 2007-263294 A

By the way, the engine is required to be reduced in weight and fuel consumption, and as part of this, the crankshaft is also required to be reduced in weight. In order to reduce the weight of the crankshaft, it is conceivable to reduce the shaft diameter of the crankpin. However, if the shaft diameter is reduced, the rigidity is lowered.
As the crankshaft becomes lighter in weight, the rigidity of the crankshaft decreases, causing bending vibration at the crankshaft when the engine is running, which increases the vibration of the engine and impairs the ride comfort of the occupant. Yes.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an engine that can reduce the bending vibration of the crankshaft while reducing the weight of the crankshaft.

  In order to achieve the above object, an engine according to the present invention includes a rim portion having an annular shape, a hub portion positioned at the center of the rim portion, and a connecting portion that connects the hub portion and the rim portion. A crank pulley around which a transmission belt is wound around the rim, a crank journal rotatably supported around the shaft, and a crank arm extending in a radial direction from the crank journal. In the engine including the crankshaft to which the hub portion is fixed, a reinforcing rib is erected on the connecting portion, and the reinforcing rib extends along the extending direction of the crank arm adjacent to the crank pulley. The hub portion and the rim portion are connected to each other.

  According to such a configuration, by providing ribs along the extending direction of the crank arm adjacent to the crank pulley in the connecting portion, the rigidity of the crank shaft is reduced due to weight reduction (reduction of the crank pin shaft diameter). The accompanying bending vibration of the crankshaft can be suppressed.

  Further, in the engine, the connecting portion includes a pair of spoke-shaped members that radially connect the hub portion and the rim portion along the extending direction, and the one spoke-shaped member faces the crank arm. The other spoke-shaped member is preferably disposed on the opposite side of the one spoke-shaped member with the hub portion interposed therebetween.

  According to such a configuration, the connecting portion is composed of a pair of spoke-shaped members that radially connect the hub portion and the rim portion, one spoke-shaped member is disposed to face the crank arm, and the other spoke-shaped member is By placing the hub on the opposite side of one spoke-like member, the weight input to the crank pulley is emphasized during combustion in the adjacent cylinder without increasing the weight of the connecting part. The rigidity can be increased.

  In the engine, the spoke-like member preferably has a dimension along the circumferential direction that gradually decreases from the hub part side toward the rim part side.

  According to such a configuration, the inertia along the circumferential direction of the spoke-like member gradually decreases from the hub side toward the rim side, whereby the inertia applied to the spoke-like member during rotation of the crank pulley. The power can be reduced.

  In the engine, the connecting portion may be configured such that the weight of the one spoke-like member is equal to the weight of the other spoke-like member, and the section modulus of the one spoke-like member is greater than that of the other spoke-like member. It is preferable that the cross-sectional shape is set so as to be larger.

According to such a configuration, the rotation of the crank pulley can be stabilized by making the weight of one spoke-like member equal to the weight of the other spoke-like member.
Further, by making the rigidity of one spoke-like member higher than the rigidity of the other spoke-like member, the tension of the transmission belt more effectively acts on the pulley side end of the crankshaft, and the pulley side The inclination of the end is restricted. As a result, it is possible to suppress bending vibration of the crankshaft accompanying a decrease in rigidity due to weight reduction of the crankshaft (reduction in the diameter of the crankpin).

  In the engine, it is preferable that the height of the reinforcing rib from the connecting portion to the tip is set larger on the hub portion side than on the rim portion side.

  According to such a configuration, the height of the reinforcing rib is made higher on the hub side than on the rim side, so that the outer peripheral side of the crank pulley is reduced in weight and the inertial force applied to the connecting portion during the rotation of the crank pulley. Can be reduced.

  In the engine, it is preferable that a plurality of the reinforcing ribs are erected on each of the pair of spoke-like members.

  According to such a configuration, by providing a plurality of ribs for each spoke-like member, rigidity can be increased while suppressing an increase in weight.

  Moreover, the said engine WHEREIN: It is preferable that the said reinforcing rib is standingly arranged in the both edge parts along the said extending direction.

  According to such a configuration, with respect to each spoke-like member, it is possible to increase rigidity while suppressing an increase in weight by erecting ribs on both edge portions of the spoke-like member along the extending direction. .

  ADVANTAGE OF THE INVENTION According to this invention, the engine which can reduce the bending vibration of a crankshaft can be provided, reducing a crankshaft weight.

It is a side view which shows the crankshaft and crank pulley which comprise the engine which concerns on 1st Embodiment. It is a perspective view which shows the crankshaft and crank pulley which comprise the engine which concerns on 1st Embodiment. It is a front view which shows the crank pulley which concerns on 1st Embodiment. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is sectional drawing along the VV line in FIG. It is a front view which shows the crank pulley which concerns on 2nd Embodiment. It is sectional drawing along the VII-VII line in FIG. It is sectional drawing along the VIII-VIII line in FIG.

<First Embodiment>
A first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. The same components are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIGS. 1 to 5, the engine 1 of this embodiment is an in-line four-cylinder engine in which four cylinders 101 are arranged in series. Further, the engine 1 of the present embodiment is installed at one end of the crankshaft 11 and the crankshaft 11 that converts the reciprocating motion of the piston 102 that reciprocates in the cylinder 101 into the rotational motion via the connecting rod 103, and the transmission belt. A crank pulley 21 that transmits the rotational force of the crankshaft 11 to the auxiliary machine via the BLT is provided.

In FIG. 2, only the piston 102 and the connecting rod 103 corresponding to one cylinder 101 are shown for convenience, but in reality, the piston 102 and the connecting rod 103 are installed in all four cylinders 101. .
A transmission 104 is connected to the other end of the crankshaft 11 (in FIG. 1, a torque converter constituting an automatic transmission is shown for convenience). Therefore, one end side of the crankshaft 11 on which the crank pulley 21 is arranged is set to the pulley side end portion 11p, and the other end side is set to the mission side end portion 11m.
Further, each cylinder 101 is set to the first cylinder 101a to the fourth cylinder (not shown) from the pulley side end portion 11p side toward the mission side end portion 11m.

As shown in FIGS. 1 and 2, the crankshaft 11 includes a crank journal 12, a crankpin 13, a crank arm 14, and a counterweight 15.
The crank journal 12 is a portion of the crankshaft 11 that is supported by a crankcase (not shown), and is rotatably supported around a shaft via a slide bearing (not shown).
The crank pin 13 is a part on which one end of the connecting rod 103 is rotatably supported. The crank pin 13 is disposed in parallel with the crank journal 12 while being offset in the radial direction from the axial center of the crank journal 12. The offset dimension L13 of the crankpin 13 is set to ½ of the stroke of the piston 102.
The crank arm 14 extends in the radial direction from the crank journal 12 and connects the crank journal 12 and the crank pin 13.
The counterweight 15 is a weight for balancing the crankshaft 11 when the crankshaft 11 rotates with the connecting rod 103 and the piston 102 connected to the crankpin 13. The counterweight 15 is disposed while extending to the opposite side of the crank arm 14 with the crank journal 12 interposed therebetween.
A crank throw 16 is constituted by the crank pin 13 and a pair of crank arms 14 that support the crank pin 13. That is, in the crankshaft 11 of the present embodiment, four crank throws 16 a to 16 d are connected by the crank journal 12.

In the present embodiment, when the weight of the crankshaft 11 is reduced, the stroke of the piston 102 and the shaft diameter of the crank journal 12 are kept as they are with respect to the conventional crankshaft (not shown). The diameter is made smaller (smaller) than before.
In the case of the shaft diameter of the conventional crankpin 13, the sum of the radius R12 of the crank journal 12 and the radius R13 of the crankpin 13 is the offset dimension L13 of the crankpin 13 (the axis of the crank journal 12 and the crankpin 13 (L13 <(R12 + R13)), part of the crankpin 13 overlaps the crank journal 12, and the interval between the crank arms 14 is the axial direction of the crankshaft 11 (Y-axis). Sufficient rigidity was ensured with respect to the load in the direction of closing or opening (narrowing) in the direction).
However, in the present embodiment, since the crank pin 13 is reduced in diameter, the sum of the radius R12 of the crank journal 12 and the radius R13 of the crank pin 13 becomes smaller than the offset dimension L13 of the crank pin 13 (L13 > (R12 + R13)), the overlap between the crankpin 13 and the crank journal 12 is eliminated. As a result, the rigidity of the crank arm 14 is lower than that of a conventional crankshaft with respect to a load in a direction in which the interval between the crank arms 14 is narrowed.

The vibration of the engine equipped with the crankshaft 11 of the present embodiment is that the vibration during combustion in the first cylinder 101a is larger than the vibration during combustion in the other cylinders. It has been confirmed in.
Then, by behavior analysis of the crankshaft 11 using CAE (computer-aided engineering), mode coupled vibration of the secondary bending mode of the crankshaft 11 in the Z-axis direction in FIG. 1 and the hub collapse mode is obtained. It became clear that.
Further, the analysis results reveal that strain energy is concentrated on the crank arm 14 and the hub portion 23 in such mode coupled vibration.
In the vibration confirmation test, the vibration of the crankshaft 11 was measured at the tip of a head 31b of a pulley bolt 31 described later.

  For the crank throws 16a to 16d of each cylinder, when the air-fuel mixture in the cylinder 101 burns and the piston 102 moves from the top dead center to the bottom dead center by the expansion pressure (combustion excitation force) of the combustion gas, the connecting rod A load is input to the crankpin 13 via 103. Then, due to the load input to the crank pin 13, a bending deformation occurs in which the distance between the crank arms 14 on the side of the crank journal 12 is narrowed. Further, the bending deformation of the crank arm 14 causes a phenomenon in which the crank journal 12 supporting the crank arm 14 tilts (swings) with the sliding bearing as a fulcrum, resulting in vibration.

  That is, the secondary bending mode of the crankshaft 11 matches the position of the antinode where the amplitude of the vibration mode is maximum with the crankpin 13 of the first cylinder 101a. Therefore, the crank pin 13 of the first cylinder 101a is inclined most in the Z-axis direction with respect to the combustion excitation force generated in each cylinder 101. Further, when the combustion excitation force is generated in the first cylinder 101a, the crank pin 13 of the first cylinder 101a tilts most in the Z-axis direction, so that the crank journals 12a and 12b of the first cylinder 101 swing most greatly. The largest engine vibration occurs.

By the way, since the vibration of the crankshaft 11 is caused by the low rigidity of the crank pulley 21, the vibration can be suppressed by increasing the rigidity of the crank pulley 21. The rigidity of the crank pulley 21 can be increased by increasing the size of each part. However, if the size of each part is simply increased, the weight of the crank pulley 21 increases.
In order to reduce the weight of the engine 1, the diameter of the crankpin 13 is reduced. However, if the weight of the crank pulley 21 is increased in order to suppress vibration caused by the reduction in the diameter, the meaning of reducing the diameter of the crankpin 13 is meant. Will disappear.
Therefore, the present application proposes a shape of the crank pulley 21 that can increase rigidity against a load input to the crank pulley 21 during combustion in the first cylinder 101a while suppressing an increase in weight.

As shown in FIGS. 2 to 5, the crank pulley 21 includes a rim portion 22 around which the transmission belt BLT is wound, a hub portion 23 fixed to the crankshaft 11, and a connecting portion that connects the rim portion 22 and the hub portion 23. 24. The crank pulley 21 is disposed on the pulley-side end portion 11p of the crankshaft 11 by a pulley bolt 31.
The rim portion 22 has an annular shape and has a three-layer structure including a small diameter portion 22a, a medium diameter portion 22b, and a large diameter portion 22c from the inside in the radial direction. The small diameter portion 22a is made of cast iron. The middle diameter portion 22b is configured by a damper made of an elastic material such as rubber. The large-diameter portion 22c is made of cast iron similar to the small-diameter portion 22a, and has a belt groove 22d along the circumferential direction on the outer periphery. Then, the transmission belt BLT is wound around the belt groove 22d.
The rim portion 22 constitutes a dynamic damper with the above three-layer structure. The rim portion 22 is a single-degree-of-freedom system resonance transmitted from the crankshaft 11 to which the rotational torque is intermittently applied to the small-diameter portion 22a by the action of the damper of the medium-diameter portion 22b and the inertial mass of the large-diameter portion 22c. The torsional vibration having a point is separated into two resonance points of the two-degree-of-freedom system, and the torsional vibration is suppressed.

The hub part 23 is formed in a disk shape by a hard resin material similar to the small diameter part 22a. The hub portion 23 is located at the center of the rim portion 22, and a fixing hole 23a is opened at the center of the plate surface. On one plate surface of the hub portion 23, the forming rib 23b is erected while forming a hexagon so as to surround the periphery of the fixing hole 23a. Note that the male screw portion 31a of the pulley bolt 31 passes through the fixing hole 23a.
The pulley bolt 31 is screwed into a female screw hole 11 a that opens at the shaft end of the pulley-side end portion 11 p of the crankshaft 11. At that time, the pulley bolt 31 has a male screw portion 31 a passing through the fixing hole 23 a of the hub portion 23, and a head portion 31 b is engaged with the periphery of the fixing hole 23 a, and the crank pulley 21 is attached to one end of the crankshaft 11. Fix it.

  As shown in FIGS. 2 and 3, the connecting portion 24 is a pair that radially connects the hub portion 23 and the rim portion 22 along the extending direction (Z-axis direction) in which the crank arm 14 extends from the crank journal 12. It is comprised by the spoke-like member. In other words, the pair of spoke-like members are arranged opposite to the arm-side spoke 24a (one spoke-like member) arranged opposite to the crank arm 14 of the adjacent first cylinder 101a and the counterweight 15 of the adjacent first cylinder 101a. Weight side spoke 24b (the other spoke-like member). That is, the arm-side spokes 24 a and the weight-side spokes 24 b are arranged linearly along the extending direction of the adjacent crank arms 14 with the hub portion 23 interposed therebetween.

  Each of the arm-side spokes 24 a and the weight-side spokes 24 b is composed of a plate-like member that faces the rotation surface of the crank pulley 21. Each of the arm-side spokes 24a and the weight-side spokes 24b has a substantially triangular shape whose dimension along the circumferential direction gradually decreases from the hub part 23 side toward the rim part 22 side. The arm-side spokes 24a and the weight-side spokes 24b are provided with reinforcing ribs 25 on both plate surfaces. The shapes of the arm-side spokes 24a and the weight-side spokes 24b are set so that the weights including the reinforcing ribs 25 are equal.

  As shown in FIGS. 2 to 5, the reinforcing rib 25 has a central portion on both front and back plate surfaces of the connecting portion 24 along the extending direction of the crank arm 14 of the first cylinder 101 a adjacent to the crank pulley 21. The outer periphery of the hub part 23 and the inner periphery of the rim part 22 are connected. Further, the reinforcing rib 25 is set so that the height dimension H25 from the plate surface to the tip of the connecting portion 24 does not change from the hub portion 23 side to the rim portion 22 side. Further, the reinforcing ribs 25 are erected on the front side and the back side in FIGS. 3 and 4, and the cross section has a cross shape. Further, the height of the reinforcing rib 25 is different between the front side and the back side, and the height H25a on the front side is set to be higher than the height H25b on the back side.

Next, the function and effect of the engine 1 according to this embodiment will be described.
A reinforcing rib 25 is provided on the connecting portion 24 along the extending direction of the crank arm 14 of the first cylinder 101a adjacent to the crank pulley 21 so as to suppress an increase in weight during combustion in the first cylinder 101a. The rigidity of the connecting portion 24 can be increased against vibration transmitted to the crank pulley 21. Accordingly, the crank pulley 21 can be prevented from falling due to vibrations transmitted to the crank pulley 21 during combustion in the first cylinder 101a.
Further, since the rigidity of the connecting portion 24 is increased, the tension of the transmission belt BLT more effectively acts on the pulley-side end portion 11p of the crankshaft 11, and the inclination of the pulley-side end portion 11p is restricted. Thereby, the bending vibration of the crankshaft 11 accompanying the reduction in rigidity due to the weight reduction of the crankshaft 11 (the diameter reduction of the crankpin 13) can be suppressed.

  The connecting portion 24 is composed of a pair of spoke-like members that connect the hub portion 23 and the rim portion 22 in a radial manner. One of the spoke-like members, the arm-side spokes 24a, is disposed opposite to the crank arm 14, and the other spoke-like shape. The weight side spoke 24b, which is a member, is disposed on the opposite side of the arm side spoke 24a with the hub portion 23 interposed therebetween, so that the crank pulley does not increase the weight of the connecting portion 24 and burns in the first cylinder 101a. The rigidity can be increased with respect to the vibration transmitted to 21.

Since the dimension along the circumferential direction of the spoke-like member is provided with a substantially triangular shape that gradually decreases from the hub portion 23 side toward the rim portion 22 side, the spoke-like member is provided during rotation of the crank pulley 21. The applied load (inertial force) can be reduced.
Although the crank pulley 21 of the present embodiment is installed in an in-line four-cylinder engine, it is not limited to the in-line four-cylinder engine for the above reasons, and is applicable to various types of engines such as a six-cylinder engine and a V-type engine. It is possible to obtain the same effect.

Second Embodiment
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Constituent elements similar to those in the first embodiment are given the same reference numerals, and redundant descriptions are omitted.
A greatly different configuration between the present embodiment and the first embodiment is a configuration of a connecting portion 24A and a reinforcing rib 25A, as shown in FIGS.
Unlike the substantially triangular shape as in the above-described embodiment, the connecting portion 24A of the present embodiment is a substantially rectangular shape with a constant dimension along the circumferential direction along the extending direction of the crank arm 14 adjacent to the crank pulley 21A. It has. Note that the connecting portion 24A is composed of a pair of spoke-shaped members including arm-side spokes 24aA and weight-side spokes 24bA, and each of the arm-side spokes 24aA and weight-side spokes 24bA is the rotation surface of the crank pulley 21A. The point comprised by the plate-shaped member which faced is the same as that of the said 1st Embodiment.

As shown in FIGS. 6 to 8, the reinforcing rib 25 </ b> A according to the present embodiment includes an outer periphery and a rim of the hub portion 23 along both edge portions on both the front and back plate surfaces of the arm-side spoke 24 a </ i> A and the weight-side spoke 24 b </ It is erected so as to connect the inner periphery of the portion 22 and has a substantially H-shaped cross section. That is, four reinforcing ribs 25A are provided upright on each of the arm side spokes 24aA and the weight side spokes 24bA along the extending direction of the crank arm 14 adjacent to the crank pulley 21A.
As shown in FIG. 8, the reinforcing rib 25A is set such that the height H25A from the plate surface to the tip of the connecting portion 24A is larger on the hub portion 23 side than on the rim portion 22 side. That is, the height dimension H25A of the reinforcing rib 25A is formed so as to gradually decrease from the hub part 23 side toward the rim part 22 side.
The reinforcing ribs 25A are erected on the front side and the back side in FIG. 6 and have a substantially H-shaped cross section. Further, the reinforcing rib 25A has a height dimension H25A different between the front side and the back side, and the front side height dimension H25aA is set to be higher than the back side height dimension H25bA.

Due to such a difference in configuration, in addition to the operational effects obtained from the first embodiment, the following operational effects are obtained in the present embodiment.
By making the height dimension H25A of the reinforcing rib 25A higher on the hub side than on the rim side, the outer peripheral side of the crank pulley 21A is reduced in weight, and the inertial force applied to the connecting portion 24A during rotation of the crank pulley 21A is reduced. be able to.
A plurality of reinforcing ribs 25A are erected along the extending direction of the crank arm 14 for each of the spoke-like members to form a substantially H-shaped cross section, thereby suppressing an increase in the weight of the crank pulley 21A. The rigidity of 24A can be increased.

In the crank pulley 21A of the present embodiment, the arm side spokes 24aA and the weight side spokes 24bA are configured by members having the same shape, but are not limited to such a form.
For example, the rigidity of the arm side spoke 24aA is greater than that of the weight side spoke 24bA while considering that the weight of the arm side spoke 24aA that is one spoke-like member and the weight side spoke 24bA that is the other spoke-like member are the same. Each section coefficient should just be set so that it may become high.
That is, the arm side spoke 24aA may be formed of a member having a substantially H-shaped cross section as in the second embodiment, and the weight side spoke 24bA may be formed of a member having a substantially cross-shaped cross section as in the first embodiment. .

By adopting such a configuration, the following operational effects can be obtained.
The rotation of the crank pulley 21A can be stabilized by making the weight of the arm-side spoke 24aA, which is one spoke-like member, equal to the weight of the weight-side spoke 24bA, which is the other spoke-like member.
By making the rigidity of the arm side spoke higher than that of the weight side spoke, the tension of the transmission belt BLT more effectively acts on the pulley side end portion 11p of the crankshaft 11, and the pulley side end portion 11p. The inclination of is regulated. Thereby, the bending vibration of the crankshaft 11 accompanying the reduction in rigidity due to the weight reduction of the crankshaft 11 (the diameter reduction of the crankpin 13) can be suppressed.

DESCRIPTION OF SYMBOLS 1 Engine 11 Crankshaft 12 Crank journal 14 Crank arm 21 Crank pulley 22 Rim part 23 Hub part 24 Connection part 24a One spoke-like member (arm side spoke)
24b The other spoke-shaped member (weight side spoke)
25 Reinforcement rib H25A Height dimension BLT Transmission belt

Claims (7)

A crank pulley comprising a rim portion having an annular shape, a hub portion located at the center of the rim portion, and a connecting portion connecting the hub portion and the rim portion, and a transmission belt is wound around the rim portion. When,
A crank journal rotatably supported around an axis, a crank arm extending in a radial direction from the crank journal, and a crank shaft having the hub portion fixed to one end;
In an engine equipped with
A reinforcing rib is erected on the connecting portion,
The reinforcing rib
An engine that connects between the hub portion and the rim portion along an extending direction of the crank arm adjacent to the crank pulley. The connecting portion is
Along the extending direction, a pair of spoke-shaped members that radially connect the hub portion and the rim portion,
One spoke-like member is disposed opposite the crank arm,
The engine according to claim 1, wherein the other spoke-like member is disposed on the opposite side of the one spoke-like member with the hub portion interposed therebetween. The spoke-shaped member is
The engine according to claim 2, wherein a dimension along a circumferential direction gradually decreases from the hub part side toward the rim part side. The connecting portion is
The cross-sectional shape is set so that the weight of the one spoke-like member is equal to the weight of the other spoke-like member, and the section modulus of the one spoke-like member is larger than that of the other spoke-like member. The engine according to claim 2 or claim 3, wherein The reinforcing rib is
The engine according to any one of claims 1 to 4, wherein a height dimension from the connecting portion to a tip is set larger on the hub portion side than on the rim portion side. The reinforcing rib is
The engine according to any one of claims 2 to 5, wherein a plurality of the pair of spoke-like members are erected on each of the pair of spoke-like members. The reinforcing rib is
The engine according to any one of claims 2 to 5, wherein the engine is erected on both edges along the extending direction.

Images