JPH11324699A - Auxiliary machine drive belt tension structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate any scraping of a coating film of a mating face to prevent loosening of a bolt by avoiding a lowering of a frictional force of the mating face between a crankshaft pulley and a crankshaft. SOLUTION: An endless auxiliary machine drive belt 6 is laid across a crankshaft pulley 3 attached to the tip part of a crankshaft of an engine 1, a water pump pulley 7, and an alternator pulley 8. An endless dummy belt 25 is also laid across a dummy pulley 24 rotatably attached to a cylinder block 15 and a crankshaft dummy pulley 21 integrally installed in the crankshaft pulley 3. The dummy pulley 24 is arranged in the opposite side of the alternator pulley 8 with the shaft end part of the crankshaft 2 set to the center and on an extension line of a bending moment vector generated by a composite force of the belt tensile forces of the auxiliary machine drive belt 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accessory driving belt tensioning structure for an engine in which a mounting bolt of a crankshaft pulley is prevented from being loosened.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a crankshaft pulley 3 is attached to a distal end of a crankshaft 2 of an engine 1 (see also FIG. 7). Rubber, for transmitting torque to auxiliary equipment such as the water pump 4 and the alternator 5;
An endless accessory drive belt 6 is engaged. The accessory drive belt 6 is connected to a water pump pulley 7 provided on the shaft of the water pump 4 from the crankshaft pulley 3 and an alternator pulley 8 provided on the shaft of the alternator 5.
And the torque of the crankshaft 2 is transmitted.

As shown in FIGS. 7 and 8, a crankshaft timing pulley 9 is coaxially and integrally provided on the engine side of the crankshaft pulley 3. A timing belt 12 is wound around a camshaft timing pulley 11 at an end of a camshaft 11A provided on the head 10. by this,
The torque of the crankshaft 2 is transmitted to the camshaft 11A.

As shown in FIGS. 7 and 8, the crankshaft pulley 3 is attached to the distal end of the crankshaft 2 by a single bolt 13. At this time, the crankshaft pulley 3 is pulled in a certain direction by the accessory drive belt 6 which is engaged with the water pump pulley 7 and the alternator pulley 8.

For this reason, as shown in FIGS. 8 and 9, a combined force T _C1 of the belt tensions T _A and T _B of the accessory drive belt 6 is applied to the crankshaft pulley 3 (see a combined vector T _C1 described later). As a result, a bending moment M _A is generated to separate the crankshaft pulley 3 from the joint portion (joint surface, see FIG. 8) T between the crankshaft pulley 3 and the crankshaft 2 (see also FIG. 8).

The parallelogram in FIG. 9 shows the belt tensions T _A and T _B of the accessory drive belt 6 as vectors, and the lines T _A1 and T _{B1 with} arrows are belt tension vectors.
T _C1 is a combined force vector obtained by combining the belt tension vectors T _A1 and T _B1 . A line M _A1 with an arrow is a bending moment vector of the bending moment M _A.

In this case, the bending moment vector M _A1 is represented by the following equation. M _A1 = T _C1 × L _A where T _{C1 is} the belt tension T _A , T _{B of the} accessory drive belt 6
Resultant force vector L _A : crankshaft pulley 3 and crankshaft 2
The distance from the joint T to the resultant force vector T _C1 (see FIG. 8)
reference)

In FIG. 6, reference numeral 14 denotes a cylinder head cover, reference numeral 15 denotes a cylinder block, and reference numeral 16 denotes a cylinder block.
Denotes oil pans. Reference numeral 17 denotes an intake manifold connected to the cylinder head 10, reference numeral 18 denotes an exhaust manifold, in FIG. 8, reference numeral 19 denotes a key for retaining the crankshaft pulley 3, and reference numeral 20 denotes a timing belt guide.

As a rotation drive device for an auxiliary machine in an internal combustion engine, there is one disclosed in Japanese Patent Application Laid-Open No. 9-158746. The one disclosed in this publication arranges three auxiliary machines in a triangular point on one longitudinal side surface of an internal combustion engine, and among these auxiliary machines, one auxiliary machine (for example, a cooling water pump), A first endless belt for power transmission is wound around the crankshaft, and a second endless belt for power transmission is wound between this one accessory and the other two accessories. The bending moment of two accessories is avoided.

[0010]

In the prior art described above, as shown in FIGS. 7 and 8, the crankshaft pulley is attached to the tip of the crankshaft by a single bolt. The joint between the shaft pulley and the crankshaft is likely to be loosened. However, at present, there is no mechanism to prevent the loosening of the joint, and the only way to prevent the loosening is to increase the tightening force of the bolt.

[0011] The loosening of the connecting portion will be described in more detail. In other words, a bending moment is generated on the crankshaft pulley by the belt tension of the accessory drive belt so as to separate the joint between the crankshaft pulley and the crankshaft. For this reason, there is a problem that the contact surface pressure of the connecting portion is reduced, and the one-side contact occurs due to the non-uniform surface pressure, and the frictional force of the connecting portion is reduced. Due to the decrease in the frictional force, slippage occurs starting from the torsion torque, and the coating film of the joint portion is scraped, and the axial force of the bolt is reduced, and the bolt is eventually loosened.

[0012] Japanese Patent Application Laid-Open No. 9-158746 discloses a rotary drive device for an auxiliary machine in an internal combustion engine, which includes a first endless belt between one auxiliary machine (for example, a cooling water pump) and a crankshaft. The second endless belt is wound around one accessory and another accessory, but the bending moment of one accessory is not canceled out efficiently.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problem. A dummy pulley for reaction force is provided on the opposite side of auxiliary machinery with respect to a crankshaft pulley, and the dummy pulley and the crankshaft pulley are connected to each other. Auxiliary parts of the engine with a dummy belt interposed between them to avoid a decrease in frictional force at the joint between the crankshaft pulley and the crankshaft, to prevent the paint film at the joint from being scraped and to prevent bolts from loosening. It is an object to provide a drive belt tension structure.

[0014]

According to the first aspect of the present invention,
An endless accessory drive belt is hung between the crankshaft of the engine and the auxiliary machine, and an endless dummy belt is hung between the crankshaft and the dummy pulley rotatably mounted on the engine body. The dummy pulley is centered on the shaft end of the crankshaft,
It is characterized by being arranged on the side opposite to the auxiliary machine.

As described above, the endless accessory drive belt is hung between the crankshaft of the engine and the accessory of the engine, and furthermore, between the crankshaft and the rotatable dummy pulley provided on the engine body. Also hook the endless dummy belt. This dummy pulley is disposed on the opposite side of the auxiliary machine with respect to the shaft end of the crankshaft. During operation of the engine, the belt tension of the auxiliary machine drive belt applied to the crankshaft is reduced to reduce the bending moment. Try to keep it down.

According to a second aspect of the present invention, in the first aspect, the dummy pulley is disposed on an extension of a bending moment vector generated by a belt tension of an accessory driving belt. It is.

In this manner, the dummy pulley is arranged on the extension of the bending moment vector generated by the belt tension of the accessory drive belt, and the engine pulley is bent by reducing the belt tension of the accessory drive belt over the crankshaft during operation of the engine. Moment is greatly suppressed.

According to a third aspect of the present invention, in accordance with the first or second aspect, a crankshaft dummy pulley for engaging the dummy belt with the crankshaft is formed. Are disposed on the outermost side in the axial direction.

A crankshaft dummy pulley, on which the dummy belt is engaged, formed on the crankshaft is disposed on the outermost side in the axial direction of the crankshaft to suppress the bending moment of the accessory drive belt caused by the belt tension in a well-balanced manner.

According to a fourth aspect of the present invention, there is provided a dummy pulley rotatably mounted on an engine body, wherein a plurality of accessory drive belts are independently engaged between a crankshaft of the engine and a plurality of accessories. And an endless dummy belt between the crankshaft and the dummy pulley, wherein the dummy pulley is disposed on a side opposite to the plurality of accessories with respect to a shaft end of the crankshaft. It is assumed that.

A plurality of endless accessory drive belts are independently engaged between a crankshaft of the engine and a plurality of accessories, and a dummy pulley rotatably attached to the engine body. An endless dummy belt is also hung between the crankshaft. And
A dummy pulley is arranged on the opposite side of the plurality of accessories around the shaft end of the crankshaft to reduce the belt tension of the accessory drive belt applied to the crankshaft during operation of the engine and reduce the bending moment. Try to suppress.

According to a fifth aspect of the present invention, in accordance with the fourth aspect, the dummy pulley has a plurality of accessory drive belts independently engaged between the crankshaft and a plurality of accessories. Are arranged on an extension of a combined bending moment vector obtained by combining the individual bending moment vectors.

As described above, the dummy pulley is arranged on an extension of the combined bending moment vector obtained by combining the individual bending moment vectors of the plurality of accessory drive belts, and the auxiliary drive belt of the accessory drive belt that is applied to the crankshaft during operation of the engine. The belt moment is greatly reduced by reducing the belt tension.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3 by attaching the same reference numerals to the same members as in FIGS. In the figure, a crankshaft pulley 3 is attached to a tip end of a crankshaft 2 disposed along the longitudinal direction of the engine 1 by bolts 13.

As shown in FIG. 2, a crankshaft timing pulley 9 is formed coaxially and integrally with one side of the crankshaft pulley 3, that is, on the engine 1 side. In the figure, the crankshaft dummy pulley 21 is coaxial and integrally formed. That is, the crankshaft dummy pulley 21 is mounted on the outermost side of the crankshaft 2 in the axial direction.

The crankshaft pulley 3 and the engine 1
An endless accessory drive belt 6 is wound around a water pump pulley 7 and an alternator pulley 8 provided on respective drive shafts of a water pump 4 and an alternator 5, which are the auxiliary devices. Force is transmitted to each of the accessories 4,5. A timing belt 12 is engaged between the crankshaft timing pulley 9 and a camshaft timing pulley 11 provided on the cylinder head 10.

The cylinder block 15 which is the main body of the engine 1 is provided with a downward bracket 22. A dummy pulley 24 is attached to a tip of a shaft portion 23 provided on the bracket 22 by a bolt 23A. I have. An endless dummy belt 25 is wound around the dummy pulley 24 and the crankshaft dummy pulley 21 provided integrally with the crankshaft pulley 3.

By wrapping the dummy belt 25 in this manner, as shown in FIGS. 2 and 3, the resultant force T _C1 (the later-described resultant force vector) of the belt tensions T _A and T _B of the accessory drive belt 6 is applied. T _C1 ), and the resultant force T of the belt tensions T _X and T _Y of the dummy belt 25 described later and the bending moment M _A (see the bending moment vector M _A1 ).
_Z1 and (later the resultant force vector T _C1 reference) bending moment generated by M _D (see bending moment vector M _D1) comes to equilibrium. In other words, the moment M _D bending by Damipuri 24 and the dummy belt 25
Thereby, the bending moment M _A caused by the auxiliary equipment such as the water pump 4 and the alternator 5 and the auxiliary equipment drive belt 6 is canceled.

This will be described in detail with reference to the vectors shown in FIGS. In FIG. 3, the crankshaft pulley 3 is cranked by a combined force T _C1 (combined force vector T _C1 ) obtained by combining the belt tension vectors T _A1 and T _B1 of the belt tensions T _A and T _B of the accessory drive belt 6. _A bending moment M _A (bending moment vector M _A1 ) acting to separate the shaft pulley 3 from the coupling portion T of the crankshaft 2 (see FIG. 2) acts.

On the other hand, the dummy pulley
Belt tension T_X , T_Y Belt tension vector
T_X1, T_Y1Combined power T_Z1(Synthetic force vector
T_Z1), A crank integrated with the crankshaft pulley 3
The auxiliary drive belt is attached to the rank shaft dummy pulley 21.
6 bending moment M_A (Bending moment vector
M _A1) And the bending moment M in the opposite direction_D (Bending Momen
To vector M_D1) Is working.

In order to cancel the bending moment M _A of the crankshaft pulley 3 and to generate the bending moment M _D in this manner, the belt tension T _X of the dummy belt 25 is set.
Determining the mounting position of the T _Y and Damipuri 24. For this reason, the mounting position of the dummy pulley 24 is determined by the combined force vector T _A1 and T _B1 of the accessory drive belt 6.
It is located on the extension of _C1 .

The bending moment vector M _A1 of the crankshaft pulley 3 by the accessory drive belt 6 is represented by the following equation. M _A1 = T _C1 × L _A where T _{C1 is} the belt tension T _A , T _{B of the} accessory drive belt 6
Resultant force vector L _A : crankshaft pulley 3 and crankshaft 2
And the distance from the joint T to the combined vector T _C1 (see FIG. 2).

Further, the crankshaft dummy pulley 21 by the dummy belt 25 bending moment vector M _D1
Is represented by the following equation. −M _D1 = − (T _Z1 × L _D ) where T _{Z1 is} the belt tension T _X , T _{Y of the} dummy belt 25.
Resultant force vector L _D : crankshaft pulley 3 and crankshaft 2
From the joint T to the composite vector T _Z1 (see FIG. 2)

Accordingly, the relationship between the bending moment vector M _{A1 of the} accessory drive belt 6 applied to the crankshaft pulley 3 and the bending moment vector M _D1 of the dummy belt 25 for canceling the bending moment M _A1 is shown below. M _A1 = T _C1 × L _A = −M _D1 = − (T _Z1 × L _D ) or M _A1 + M _D1 = (T _C1 × L _A ) + (T _Z1 × L _D ) Thus, the dummy pulley 24 is arranged. With this arrangement, the bending moment M _A of the accessory drive belt 6 is canceled, and the joint T between the crankshaft pulley 3 and the crankshaft 2 is firmly held without being separated.

Since the present invention is constructed as described above, the engine 1 is operated, the crankshaft 2 is rotated, the crankshaft pulley 3 is rotated, and the rotational force is applied to the water pump pulley 7 and the alternator pulley 8 The power is transmitted to the water pump 4 and the alternator 5 via the accessory drive belt 6 engaged with the motor.

At the time of rotation of the crankshaft pulley 3, the auxiliary drive belt 6 is attached to the crankshaft pulley 3.
Belt tension T _A, by a synthetic force T _C1 was synthesized T _B (resultant force vector T _C1), although the bending moment M _A as to separate the coupling portion T of the crankshaft pulley 3 and the crank shaft 2 is generated a crank shaft dummy pulley 21 formed integrally with the crankshaft pulley 3, the dummy belt 25 is engaged between the Damipuri 24 provided in the engine body, the dummy belt 25 belt tension T _X, by T _Y the combined resultant force T _Z1 (resultant force vector T _Z1), a crankshaft pulley 3 integral with the crankshaft dummy pulley 21
The bending moment M _D (bending moment vector M _D1 ) which cancels the bending moment M _A (bending moment vector M _A1 ) generated by the accessory drive belt 6.
Occurs. Therefore, loosening of the crankshaft pulley 3 is suppressed.

The dummy pulley 24 is arranged on the extension line of the bending moment vector M _A1 generated by the resultant force vector T _C1 of the belt tensions T _A and T _B of the accessory drive belt 6, but this is not the case. It may be simply arranged on the opposite side of auxiliary equipment such as the water pump 4 and the alternator 5 about the shaft end of the crankshaft 2.
Even in this case, the bending moment M _A of the crankshaft pulley 3 can be suppressed to some extent.

Next, the embodiment shown in FIGS. 4 and 5 will be described. 1 to 3 are denoted by the same reference numerals. In this embodiment, a plurality (two) of accessory drive belts are used. Basically Figures 1 to 3
However, it is necessary to combine a plurality of bending moments generated by the two accessory drive belts 6A and 6B.

That is, as shown in FIGS. 4 and 5, a first accessory drive belt 6A is hung between the first crankshaft pulley 3A, the water pump pulley 7 and the alternator pulley 8. Thereby, the first auxiliary machine drive belt 6A is attached to the first crankshaft pulley 3A.
Belt tensions T _A , T _B of the belt tension vectors T _A1 , T _B
The _B1 synthesized composite force T _C1 (see resultant force vector T _C1), the junction of the first crankshaft pulley 3A, a crankshaft pulley 3A and the crank shaft 2 T
(See FIG. 4) Bending moment M to be further separated
_A is generated (the bending moment vector M _{A1 in} FIG. 5).
See also

The bending moment vector M _{A1 in} this case is represented by the following equation. M _A1 = T _C1 × L _A where, T _C1: belt tension T of the first accessory drive belt 6A
_A , T _B, the resultant force vector L _A : the distance from the joint T between the first crankshaft pulley 3A and the crankshaft 2 to the resultant force vector T _C1 (see FIG. 4).

The second crankshaft pulley 3 is coaxially formed integrally with the first crankshaft pulley 3A.
B and compressor pulley 26 of air conditioner (not shown)
A second auxiliary device drive belt 6B is wound around a pump pulley 27 of a power steering pump (not shown).

Thus, the second crankshaft pulley
The belt tension T of the second auxiliary device driving belt 6B
_D , T_E Belt tension vector T_D1, T_E1The combination of
Vigor T _F1(Synthetic force vector T_F12)
Connection of link shaft pulley 3B to crankshaft 2
Moment to be bent away from part T (see FIG. 4)
To M_B Is generated (the bending moment vector M shown in FIG. 5)._B1
reference).

In this case, the bending moment vector M _B1 is represented by the following equation. M _B1 = T _F1 × L _B where T _{F1 is} the belt tension T of the second auxiliary device drive belt 6B.
_D, the resultant force vector L _B of T _E: second crankshaft pulley 3B and the distance from the coupling portion T of the crank shaft 2 to the resultant force vector T _F1 (see FIG. 4)

A combined bending moment vector M _C1 is generated by the bending moment vector M _A1 of the first crank shaft pulley 3A and the bending moment vector M _B1 of the second crank shaft pulley 3B shown in FIG. To cancel the resultant bending moment vector M _C1 ,
On the extension of the resultant bending moment vector M _C1 , and
The dummy pulley 2 is located at a position opposite to the water pump 7 and the compressor pulley 27 around the first crankshaft pulley 3A and the second crankshaft pulley 3B.
4 is installed.

The dummy pulley 24, the first crankshaft pulley 3A and the second crankshaft pulley 3B
The dummy belt 25 is wound around the crankshaft dummy pulley 21 provided coaxially with the belt, and the belt tension vectors T _X1 and T _Y1 of the belt tensions T _X and T _Y of the wound dummy belt 25 are _calculated . Due to the combined resultant force T _Z1 (combined force vector T _Z1 ), the crankshaft dummy pulley 21 has a bending moment MD (bending moment vector M _{D) in the} opposite direction to the combined bending moment vector M _C1.
D1 ) is generated, and the bending moment M _D (bending moment vector M _D1 ) cancels the resultant bending moment (the resultant bending moment vector M _C1 ).

[0046] In this case, the bending moment vector M _D1 crankshaft dummy pulley is indicated by the following equation. M _D1 = T _Z1 × L _D where, T _Z1: belt tension of the dummy belt 25 T _X, T _Y
The resultant force vector L _D: a distance from the coupling portion T between the first crankshaft pulley 3A and the crank shaft 2 to the combined vector T _Z1 (see FIG. 4).

Therefore, the resultant bending moment vector M _C1 and the bending moment vector M
_The following equation holds between _D1 and _D1 . M _C1 + M _D1 = M _C1 + (T _Z1 × L _D )

The operation of the embodiment shown in FIGS. 4 and 5 will be described below. When the engine 1 is operated to rotate the crankshaft 2, the first crankshaft pulley 3
A and the second crankshaft pulley 3B rotate, and the water pump pulley 7 and the alternator pulley 8, which are auxiliary equipment, rotate via the first auxiliary equipment drive belt 6A and the second auxiliary equipment drive belt 6B, and the air conditioner Compressor pulley 26 and power steering pump pulley 27
Rotates.

With this rotation, the belt tension T of the first auxiliary machine drive belt 6A is applied to the first crankshaft pulley 3A.
_A bending force M _A (bending moment vector M _A1 ) is generated by a combined force T _C1 (synthesized force vector T _C1 ) of _A and T _B , and the belt of the second accessory drive belt 6B is attached to the second crankshaft pulley 3B. moment M _B bent by the tension T _D, the resultant force of T _E T _F1 (resultant force vector T _F1)
(Bending moment vector M _B1 ) is generated. Therefore, a combined bending moment M _C of the bending moment M _A and the bending moment M _B is generated on the first crank shaft pulley 3A and the second crank shaft pulley 3B.

[0050] However, as an extension of the synthesis bending moment M _C, and Damipuri opposite to the first crankshaft pulley 3A and the second crankshaft pulley 3B 2
4, a dummy belt 25 is wound around the dummy pulley 24 and a crankshaft dummy pulley 21 provided integrally with the first crankshaft pulley 3A and the second crankshaft pulley 3B. since moment M _D bending by the dummy belt 25
As a result, the resultant bending moment M _C is canceled. As a result, the first crankshaft pulley 3A and the second crankshaft pulley 3B are firmly held on the crankshaft 2.

It should be noted that a plurality of accessories, for example,
Between the pump 4, the alternator 5, and the crankshaft 2
Tension T of the first auxiliary device driving belt 6A
_A , T _B Combined force T_C1(Synthetic force vector T_C1Song by
Moment vector M_A1And air conditioner compressor
Pulley 26, power steering pump pulley 27 and
And the second auxiliary device driven between the crankshafts 2
Belt tension T of belt 6B_D , T_E Combined force T_F1(Synthesis
Force vector T_F1) Bending moment vector M_B1When
Bending moment vector T obtained by combining_C1On the extension of
The dummy pulley 24 is arranged at
Instead of the dummy pulley 24, the shaft end of the crankshaft 2
Centering on a plurality of accessories, such as water pumps
4 and alternator 5, and air conditioner compressor
Pulley 26 and power steering pump pulley 27
May be simply arranged on the opposite side. like this
Anyway, the bending moment of the crankshaft pulley 3
M_A Can be suppressed to some extent.

[0052]

According to the first aspect of the present invention, the dummy pulley is disposed on the side opposite to the auxiliary machine of the engine with the center of the shaft end of the crankshaft as a center. The belt tension and bending moment of the machine drive belt can be suppressed. Thus, it is possible to suppress a decrease in the frictional force at the joint between the crankshaft and the crankshaft pulley, to suppress the wear of the coating film at the joint, and to prevent the bolt from being loosened.

According to a second aspect of the present invention, the dummy pulley is
Since it is arranged on the extension of the bending moment vector generated by the belt tension of the accessory drive belt, the belt tension and the bending moment of the accessory drive belt applied to the crankshaft during operation of the engine can be greatly suppressed. As a result, a reduction in the frictional force at the joint between the crankshaft and the crankshaft pulley can be significantly suppressed, and the wear of the coating film at the joint can be reliably suppressed. Therefore, loosening of the bolt can be reliably prevented.

According to the third aspect of the present invention, the dummy pulley on the crankshaft, on which the dummy belt engages, is disposed on the outermost side in the axial direction of the crankshaft. The bending moment can be suppressed in a well-balanced manner.

According to a fourth aspect of the present invention, the dummy pulley is
Since the plurality of engine accessories are disposed on the opposite side of the crankshaft shaft center, the belt tension and bending moment of the accessory drive belt applied to the crankshaft during operation of the engine can be suppressed. . Thus, it is possible to suppress a decrease in the frictional force at the joint between the crankshaft and the crankshaft pulley, to suppress the wear of the coating film at the joint, and to prevent the bolt from being loosened.

According to a fifth aspect of the present invention, the dummy pulley is
Since the individual bending moment vectors of multiple accessory drive belts are arranged on the extension of the combined bending moment vector, the belt tension and bending moment of the accessory drive belt on the crankshaft during engine operation are greatly reduced. can do. As a result, it is possible to suppress a decrease in the frictional force at the joint between the crankshaft and the crankshaft pulley, and it is possible to reliably suppress the wear of the coating film at the joint. Therefore, loosening of the bolt can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of an embodiment of the present invention and showing an arrangement of a crankshaft pulley, a water pump pulley, and the like provided in an engine.

FIG. 2 is an enlarged sectional view schematically showing a part of a crankshaft pulley and a dummy pulley of FIG.

FIG. 3 is a schematic diagram showing a belt tension vector, a resultant force vector, and a bending moment vector of the accessory drive belt and the dummy belt of FIG.

FIG. 4 is an enlarged sectional view schematically showing a part of a crankshaft pulley and a dummy pulley provided in an engine in another example of the embodiment of the present invention.

FIG. 5 is a schematic view showing a combined bending moment vector of two accessory drive belts and a bending moment vector of a dummy belt in another example of the embodiment of the present invention.

FIG. 6 is a front view showing a conventional arrangement of a crankshaft pulley and a water pump pulley of an engine.

FIG. 7 is a cross-sectional view of FIG. 6 showing the mounting of the crankshaft pulley and the crankshaft timing pulley.

FIG. 8 is a cross-sectional view schematically showing attachment of the crankshaft pulley and the crankshaft timing pulley shown in FIG.

9 is a schematic diagram showing a belt tension vector, a resultant force vector, and a bending moment vector of the accessory drive belt of FIG.

[Explanation of symbols]

Reference Signs List 1 engine 2 crankshaft 4 water pump 5 alternator 6 accessory drive belt 6A first accessory drive belt 6B second accessory drive belt 15 cylinder block 21 crankshaft dummy pulley 24 dummy pulley 25 dummy belt 26 compressor pulley 27 pump pulley M _A bending moment M _B bending moment M _A1 bending moment vector M _B1 bending moment vector M _C1 synthesis bending moment vector T _A belt tension T _B belt tension

Claims (5)

[Claims] An endless accessory drive belt is hung between a crankshaft of an engine and an accessory, and a dummy pulley rotatably mounted on an engine body, and an endless dummy belt between the crankshaft and the engine. Wherein the dummy pulley is disposed on a side opposite to the accessory with respect to a shaft end of the crankshaft. 2. The accessory drive belt tensioning structure for an engine according to claim 1, wherein the dummy pulley is disposed on an extension of a bending moment vector generated by a belt tension of the accessory drive belt. 3. A crankshaft dummy pulley on which the dummy belt is engaged with the crankshaft is formed.
3. The belt structure for driving an auxiliary machine of an engine according to claim 1, wherein the crankshaft dummy pulley is arranged on an outermost side in an axial direction of the crankshaft. 4. A dummy pulley rotatably mounted on an engine body, wherein a plurality of accessory drive belts are independently engaged between a crankshaft of the engine and a plurality of accessories, and the crankshaft is An endless dummy belt is interposed therebetween, and the dummy pulley is arranged on a side opposite to the plurality of accessories with respect to an end of the shaft of the crankshaft. Drive belt tension structure. 5. A combined bending moment vector obtained by combining individual bending moment vectors of a plurality of accessory drive belts independently engaged with the crankshaft and a plurality of accessories, respectively, in the dummy pulley. The accessory driving belt tensioning structure for an engine according to claim 4, wherein the belt is arranged on an extension line.