JPH08226527A - Pulley mounting structure of crank shaft - Google Patents

Abstract

PURPOSE: To reduce the weight of a crank shaft so as to ensure its strength by forming a whole peripheral groove which is positioned between a root section of a front shaft section and a fitting section for a pulley of the crank shaft. CONSTITUTION: Load F1 which is input from a timing belt which is stretched around a timing belt pulley 2 and load F2 , F3 , and F4 which are input from each auxiliary machinery belt which is stretched around a belt pulley 3 act on a front shaft section 1 of a crank shaft 1 which is supported on one side on a main bearing through a journal section 14. Flexural rigidity of the front shaft section 11 is reduced in a section where a whole peripheral groove 19 is formed. Since the whole peripheral groove 19 is formed between a fitting section of the front shaft section 11 for the belt pulley 3 and its root section 13, bending stress which acts on the crank shaft 1 due to load F2 , F3 , and F4 is dispersed in the section where the whole peripheral groove 19 is formed to suppress the generation of stress concentration in the root section 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved crankshaft pulley mounting structure in an engine.

[0002]

2. Description of the Related Art For example, a conventional crankshaft pulley mounting structure is shown in FIG. 3 (see Japanese Utility Model Laid-Open No. 3-130461).

To explain this, a journal portion 14 is formed in the middle of the crankshaft 1, and the journal portion 14 is rotatably supported by a main bearing (not shown).

At the axial end of the crankshaft 1, the front shaft portion 1 which axially projects from the journal portion 14 is formed.
1 is formed. The timing belt pulley 2 and the belt pulley 3 are fitted to the front shaft portion 11 and fastened via bolts 4.

The timing belt pulley 2 rotates together with the crankshaft 1 and circulates a timing belt (not shown) to transmit power to a valve train including a camshaft and the like.

The belt pulley 3 rotates together with the crankshaft 1 and circulates a belt (not shown) to transmit power to various auxiliary machines such as an alternator.

[0007]

A timing belt pulley 2 is attached to a front shaft portion 11 of a crankshaft 1, which is cantilevered on a main bearing via a journal portion 14.
The load input from the timing belt applied to the belt pulley 3 and the load input from each accessory belt applied to the belt pulley 3 act.

However, in such a conventional crankshaft pulley attachment structure, since the crankshaft 1 is formed by reducing the diameter of the front shaft portion 11 at the root portion 13, the crankshaft 1 is Bending rigidity is greatly reduced at the root portion 13,
The bending stress acting on the front shaft portion 11 due to the load input from 3 is concentrated on the root portion 13.

Therefore, since it is necessary to secure the strength of the root portion 13, there is a problem that the diameter of the front shaft portion 11 is increased and the weight of the crankshaft 1 is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to secure strength in a crankshaft pulley mounting structure while reducing the weight of the crankshaft.

[0011]

According to a first aspect of the present invention, there is provided a crankshaft pulley mounting structure, which includes a crankshaft for converting reciprocating motion of a piston into rotary motion via a connecting rod. In an engine equipped with a transmitting pulley, a crankshaft is formed with a journal portion that is rotatably supported by the engine body, and a front shaft portion that axially protrudes from the journal portion and that fits the pulley is formed at the shaft end portion of the crankshaft. A full-circumferential groove is formed on the crankshaft between the base portion of the front shaft portion and the fitting portion for the pulley and is recessed over the entire circumference.

According to a second aspect of the invention, there is provided a crankshaft pulley mounting structure according to the first aspect of the invention, wherein the crankshaft has a plurality of pulleys that are fitted to the front shaft portion of the crankshaft and transmit power. In an engine equipped with a plurality of keys for positioning each pulley, a plurality of key grooves are formed on the front shaft to engage with the keys interposed between the pulleys, and the entire circumferential groove is placed between the key grooves. Is formed at a position closer to the root side pulley than the tip side pulley.

According to a third aspect of the present invention, in the crankshaft pulley mounting structure according to the first or second aspect of the present invention, the root portion of the front shaft portion has a recessed portion over the entire circumference so as to prevent interference with the pulley. The escape groove is formed so that the minimum shaft diameter of the portion where the circumferential groove is formed is smaller than the minimum shaft diameter of the portion where the escape groove is formed.

According to a fourth aspect of the present invention, there is provided a crankshaft pulley mounting structure according to any one of the first to third aspects, wherein the crankshaft is bolted to an engine having bolts for fastening the pulley to the crankshaft. A female threaded portion that is screwed into is formed, and the entire circumferential groove is formed at a position axially separated from the female threaded portion.

[0015]

In the pulley mounting structure for the crankshaft according to the first aspect, the front shaft portion of the crankshaft, which is cantilevered by the engine body via the journal portion, receives an input from a belt or the like wound around the pulley. Load is applied.

The bending rigidity of the front shaft portion is greatly reduced at the portion where the entire circumferential groove is formed, and the entire circumferential groove is formed between the fitting portion of the front shaft portion for the pulley and the root portion. Therefore, the bending stress acting on the front shaft portion due to the load input from the pulley is dispersed to the portion where the circumferential groove is formed, and the concentration of stress on the root portion is suppressed.

In the crankshaft pulley mounting structure according to the second aspect of the invention, since the entire circumferential groove is located between the key grooves and is formed closer to the root side pulley than the tip side pulley, The moment arm of the load input from the pulley on the tip side with respect to the entire circumferential groove is lengthened to effectively disperse the bending stress acting on the front shaft part by the load input from the pulley on the tip side, resulting in stress concentration at the base part. Suppress things.

In the crankshaft pulley mounting structure according to a third aspect of the present invention, the front shaft has a structure in which the minimum shaft diameter of the portion where the circumferential groove is formed is smaller than the minimum shaft diameter of the portion where the escape groove is formed. The rigidity of the part where the entire circumference groove is formed is smaller than the rigidity of the part where the relief groove is formed, and the bending stress that acts on the front shaft part due to the load input from the pulley is effectively dispersed, and Suppresses stress concentration.

In the crankshaft pulley mounting structure according to the fourth aspect, since the entire circumferential groove is formed at a position axially separated from the female screw portion, the entire circumferential groove of the front shaft portion is formed. It is possible to prevent the occurrence of cracks or the like in the female screw portion due to the stress concentrated on the portion where

[0020]

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

In FIG. 1, reference numeral 1 denotes a crankshaft provided in the engine. The crankshaft 1 converts reciprocating motion of a piston (not shown) into rotary motion via a connecting rod. A journal portion 14 is formed in the middle of the crankshaft 1, and the journal portion 14 is rotatably supported by a main bearing (not shown).

At the axial end of the crankshaft 1, the front shaft portion 1 which axially projects from the journal portion 14 is formed.
1 is formed. The axial end portion of the crankshaft 1 is formed by gradually reducing the diameter from the journal portion 14, and the front shaft portion 11 located at the tip of the crankshaft 1 is
It is formed into a right circular cylinder with the smallest outer diameter.

The timing belt pulley 2 and the belt pulley 3 are fitted and connected to the front shaft portion 11 of the crankshaft 1.

The timing belt pulley 2 rotates together with the crankshaft 1, circulates a timing belt (not shown), and transmits power to a valve train including a camshaft and the like.

A pair of guide plates 8 are fitted and provided on the front shaft portion 11 of the crankshaft 1 so as to sandwich the timing belt pulley 2. Each disc-shaped guide plate 8 guides the timing belt so as not to come off the timing belt pulley 2.

The belt pulley 3 rotates together with the crankshaft 1 and circulates a belt (not shown) to transmit power to various auxiliary machines such as an alternator.

A bolt 4 that is screwed onto the crankshaft 1 is provided. The crankshaft 1 is formed with a female screw portion 12 into which the bolt 4 is screwed. The bolt 4 is inserted from the axial end of the crankshaft 1 and screwed into the female screw portion 12.

A washer 5 is interposed between the head of the bolt 4 and the belt pulley 3. The bolt 4 fastens the timing belt pulley 2 and the belt pulley 3 to the crankshaft 1 via the washer 5.

A key 6 for positioning the timing belt pulley 2 and a key 7 for positioning the belt pulley 3 are provided on the crankshaft 1, respectively.

Key grooves 22 and 23 are respectively formed on the inner peripheral surfaces of the boss portions of the timing belt pulley 2 and the belt pulley 3 along the axial direction.

On the other hand, on the outer peripheral surface of the front shaft portion 11, key grooves 16 and 17 recessed in a half-moon shape are formed along the axial direction.

The half-moon shaped key 6 is interposed between the key groove 22 and the key groove 16 and positions the timing belt pulley 2 with respect to the crankshaft 1. The half-moon shaped key 7 is interposed between the keyway 23 and the keyway 17,
The belt pulley 3 is positioned with respect to the crankshaft 1.

An escape groove 18 is formed in the root portion 13 of the front shaft portion 11 over the entire circumference. The escape groove 18 is recessed with respect to the outer peripheral surface of the front shaft portion 11,
The interference with the inner circumference of the belt pulley 2 or the guide plate 8 is prevented.

A circumferential groove 19 is formed in the middle of the front shaft portion 11 over the entire circumference. The entire circumferential groove 19 is recessed with respect to the outer peripheral surface of the front shaft portion 11, and suppresses the concentration of stress on the root portion 13 as described later.

The bottom of the entire circumferential groove 19 has a cross section curved in an arc shape and is curved in a concave shape to disperse bending stress generated in the front shaft portion 11 as described later.

The entire circumferential groove 19 is formed between the root portion 13 and the fitting portion for the timing belt pulley 2. The entire circumferential groove 19 is located between the key grooves 16 and 17, and is formed close to the key groove 16.

In the front shaft portion 11, the minimum axial diameter D ₁ of the portion where the circumferential groove 19 is formed is smaller than the minimum axial diameter D _{2 of the} portion where the clearance groove 18 is formed. That is, the entire circumferential groove 19 is deeper than the escape groove 18.

The entire circumferential groove 19 is formed at a position axially separated from the female screw portion 12. End 24 of female screw portion 12
Is formed closer to the root portion 13 in the axial direction than the entire circumferential groove 19.

With the above construction, the operation will be described.

The front shaft portion 1 of the crankshaft 1 which is cantilevered on the main bearing via the journal portion 14.
1 includes a load F ₁ input from the timing belt wound around the timing belt pulley 2 and loads F ₂ , F ₃ and F ₄ input from each accessory belt wound around the belt pulley 3. Works.

Since the crankshaft 1 has a structure in which the front shaft portion 11 is formed by reducing its diameter at the root portion 13, the bending rigidity of the crankshaft 1 is greatly reduced at the root portion 13, and the entire circumferential groove 19 is formed. If not, the bending stress acting on the crankshaft 1 due to the loads F _{1 to} F ₄ input from the pulleys 2 and 3 concentrates on the root portion 13.

The bending rigidity of the front shaft portion 11 is greatly reduced at the portion where the circumferential groove 19 is formed, and the circumferential groove 19 is located between the fitting portion of the front shaft portion 11 for the belt pulley 3 and the root portion 13. Because of the structure formed by the above, loads F ₂ , F ₃ , F ₄ input from the belt pulley 3
Bending stress acting on the crankshaft 1 by the circumferential groove 19
Are dispersed in the area where the ridges are formed to suppress the concentration of stress on the root portion 13.

Since the entire circumferential groove 19 is located between the key grooves 16 and 17 and is formed in the vicinity of the key groove 16, the load F ₂ applied to the entire circumferential groove 19 from the belt pulley 3 is The moment arms of F ₃ and F ₄ are lengthened, and the bending stress acting on the crankshaft 1 by the loads F ₂ , F ₃ and F ₄ input from the belt pulley 3 is effectively dispersed, and stress concentration occurs at the root portion 13. Suppress things.

The minimum shaft diameter D ₁ of the entire circumferential groove 19 is set to the clearance groove 18
Due to the structure in which it is formed smaller than the minimum shaft diameter D _{2 of} the belt pulley 3, the rigidity of the front shaft portion 11 where the entire circumferential groove 19 is formed is smaller than the rigidity where the minimum shaft diameter D ₁ is formed. Loads input from F ₂ , F ₃ , F ₄
Thus, the bending stress acting on the front shaft portion 11 is effectively dispersed, and the stress concentration at the root portion 13 is suppressed.

The entire circumferential groove 19 of the front shaft portion 11 has a structure in which the circumferential circumferential groove 19 having a cross section curved in an arc shape is formed at a position axially separated from the female screw portion 12.
The internal threaded portion 1 is caused by the stress concentrated on the area where 9 is formed.
It is possible to prevent cracks and the like from occurring in 2.

Next, another embodiment shown in FIG. 2 will be described. It should be noted that the same reference numerals are used for the portions corresponding to those in FIG.

A sprocket 32, a drive spacer 31, and a belt pulley 3 are fitted and provided on the front shaft portion 11 of the crankshaft 1.

The sprocket 32 is the crankshaft 1
Along with this, a chain (not shown) circulated around the same is circulated to transmit power to a valve train including a camshaft and the like.

The drive spacer 31 rotates together with the crankshaft 1 and drives an oil pump (not shown).

The bolt 4 fastens the sprocket 32, the drive spacer 31, and the belt pulley 3 to the crankshaft 1 via the washer 5.

A key 36 for positioning the sprocket 32 and the drive spacer 31 with respect to the crankshaft 1 and a key 7 for positioning the belt pulley 3 are provided. Key grooves 34 and 35 are formed along the axial direction on the inner peripheral surfaces of the sprocket 32 and the drive spacer 31 which are fitted to the front shaft portion 11. On the other hand, on the outer peripheral surface of the front shaft portion 11, a key groove 37 that is recessed in a half-moon shape is formed along the axial direction. The half-moon shaped key 36 has keyways 34 and 35 and a keyway 37.
The sprocket 32 and the drive spacer 31 are positioned with respect to the crankshaft 1.

A full-circumferential groove 19 is formed in the middle of the front shaft portion 11 over the entire circumference thereof, and suppresses the concentration of stress on the root portion 13, as will be described later. The entire circumferential groove 19 is formed with a cross section curved in an arc shape.

The entire circumferential groove 19 is formed between the base portion 13 and the fitting portion for the belt pulley 3. The entire circumferential groove 19 is located between the key grooves 37 and 17, and
It is formed in the vicinity of 7.

With the above construction, the operation will be described below.

By the load F ₁ input from the chain wound around the sprocket 32 and the loads F ₂ , F ₃ and F ₄ input from the accessory belts wound around the belt pulley 3, the crankshaft 1 Bending stress acts on. Since the crankshaft 1 has a structure in which the front shaft portion 11 has a diameter reduced at the root portion 13, the bending rigidity of the crankshaft 1 is greatly reduced at the root portion 13 and is input from the sprocket 32 and the belt pulley 3. Load F
_The bending stress acting on the crankshaft 1 due to ₂ , F ₃ and F ₄ is concentrated on the root portion 13.

Since the entire circumferential groove 19 is formed between the fitting portion of the front shaft portion 11 for fitting the belt pulley 3 and the root portion 13, the bending rigidity of the crankshaft 1 is formed by the entire circumferential groove 19. is greatly reduced at the site were, by the load F _2, F _3, F ₄ inputted from the belt pulley 3 by dispersing bending stress acting on the crankshaft 1, suppresses stress that concentration occurs at the base portion 13.

[0057] All peripheral groove 19 is located between each keyway 37,17, since it is formed adjacent to the keyway 37, the load F ₂ is inputted from the belt pulley 3 with respect to the total circumferential groove 19, The moment arms of F ₃ and F ₄ are lengthened, and the bending stress acting on the crankshaft 1 by the loads F ₂ , F ₃ and F ₄ input from the belt pulley 3 is effectively dispersed, and stress concentration occurs at the root portion 13. Suppress things.

[0058]

As described above, the pulley mounting structure for a crankshaft according to claim 1 is provided with a crankshaft for converting the reciprocating motion of the piston into a rotary motion via a connecting rod, and the crankshaft is connected to the crankshaft to drive power. In an engine provided with a pulley for transmitting power, a crankshaft is formed with a journal portion that is rotatably supported by the engine body, and a front shaft portion into which the pulley is fitted by axially protruding from the journal portion at the shaft end portion of the crankshaft. The crankshaft is formed between the root of the front shaft and the fitting portion for the pulley, and a full-circumferential groove that is recessed over the entire circumference is formed. The bending stress that acts on the base is dispersed in the area where the circumferential groove is formed, and stress concentration occurs at the root. Suppressed, while reducing the weight of the crank shaft, it is possible to increase the supporting rigidity of the pulley.

According to a second aspect of the invention, there is provided a crankshaft pulley mounting structure according to the first aspect of the invention, wherein a plurality of pulleys are fitted to the front shaft portion of the crankshaft and transmit power, and the pulleys are mounted on the crankshaft. In an engine provided with a plurality of keys for positioning the pulleys, a plurality of key grooves that engage with the keys interposed between the pulleys are formed on the front shaft portion, and the entire circumferential groove is provided between the key grooves. Since the entire circumferential groove is formed closer to the root side pulley than the tip side pulley, the moment arm for the load input from the tip side pulley is lengthened to The bending stress that acts on the crankshaft due to the input load is effectively dispersed, and the stress concentration at the root is suppressed, and the crankshaft is lightened. While reducing the reduction, it is possible to increase the supporting rigidity of the pulley.

According to a third aspect of the present invention, in the crankshaft pulley mounting structure according to the first or second aspect of the present invention, the base shaft portion of the front shaft portion has a recess over the entire circumference so as to prevent interference with the pulley. Since the clearance groove is formed and the minimum shaft diameter of the part where the circumferential groove is formed is made smaller than the minimum shaft diameter of the part where the clearance groove is formed, the front shaft part has rigidity of the part where the circumferential groove is formed. However, it becomes smaller than the rigidity of the part where the minimum shaft diameter is formed, the bending stress acting on the front shaft part is effectively dispersed by the load input from the pulley, and the stress concentration at the root part is suppressed, It becomes possible to increase the supporting rigidity of the pulley while reducing the weight of the pulley.

According to a fourth aspect of the present invention, in the crankshaft pulley mounting structure according to any one of the first to third aspects of the present invention, in the engine provided with a bolt for fastening the pulley to the crankshaft, the crankshaft is bolted. By forming a female screw portion that is screwed into, and forming the entire circumferential groove at a position axially separated from the female screw portion, due to the stress concentrated on the portion where the entire circumferential groove of the front shaft portion is formed,
It is possible to prevent cracks and the like from occurring in the female screw portion and to reduce the weight of the crankshaft.

[Brief description of drawings]

FIG. 1 is a sectional view of a crankshaft and the like showing an embodiment of the present invention.

FIG. 2 is a sectional view of a crankshaft and the like showing another embodiment of the present invention.

FIG. 3 is a sectional view of a crankshaft and the like showing a conventional example.

[Explanation of symbols]

 1 Crank Shaft 2 Timing Belt Pulley 3 Belt Pulley 4 Bolt 6 Key 7 Key 11 Front Shaft Part 12 Female Threaded Part 13 Root Part 14 Journal Part 16 Key Groove 17 Key Groove 18 Escape Groove 19 Full Circumferential Groove 31 Drive Spacer 32 Sprocket 34 Key Groove 35 key groove 36 key

Claims (4)

[Claims] 1. An engine having a crankshaft for converting reciprocating motion of a piston into rotary motion through a connecting rod, and a pulley connected to the crankshaft for transmitting power, the crankshaft being rotatably supported by an engine body. The front shaft part that axially projects from the journal part to fit the pulley is formed at the shaft end part of the crankshaft, and the base part of the front shaft part and the fitting part to the pulley are fitted to the crankshaft. A crankshaft pulley mounting structure, characterized in that a full-circumferential groove that is located between and is formed over the entire circumference is formed. 2. An engine having a plurality of pulleys fitted to a front shaft portion of a crankshaft for transmitting power, and having a plurality of keys for positioning each pulley with respect to the crankshaft, wherein each pulley is provided on the front shaft portion. A plurality of key grooves that engage with the key that is inserted between them are formed, and the entire circumferential groove is formed between each key groove, and the entire circumferential groove is formed on the root side pulley rather than the tip side pulley. The crankshaft pulley attachment structure according to claim 1, wherein the crankshaft pulley attachment structure is formed at a position close to the. 3. A relief groove that is recessed over the entire circumference is formed at the base portion of the front shaft portion so as to prevent interference with the pulley, and the relief groove has a minimum shaft diameter at the portion where the circumferential groove is formed. The crankshaft pulley mounting structure according to claim 1 or 2, wherein the shaft is formed to have a diameter smaller than a minimum shaft diameter of a portion to be formed. 4. An engine provided with a bolt for fastening a pulley to a crankshaft, wherein a crankshaft is formed with an internal thread portion to be screwed with the bolt, and the entire circumferential groove is formed at a position axially separated from the internal thread portion. The structure for mounting a pulley on a crankshaft according to any one of claims 1 to 3, characterized in that: