JPH063152Y2 - Engine belt pulley fixing structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fixing structure of an engine belt pulley, particularly an intermediate pulley arranged between a crank pulley and a cam pulley.

(Prior Art) In an engine in which a camshaft for driving intake / exhaust valves provided on an upper part of a cylinder head is driven by a timing belt drive mechanism, for example, a practically open Sho 62-90.
As described in Japanese Patent No. 903, an intermediate pulley such as a tensioner pulley or an idler pulley for adjusting tension or a winding angle of a timing belt is usually arranged on an end surface of a cylinder block or a cylinder head in a cylinder row direction. Is.

By the way, a case forming a timing belt chamber that also functions as a pump housing of a water pump or the like is usually fastened to the end surface of the cylinder block in which such a timing belt drive mechanism is disposed, and is disposed at this position. The support shaft of the intermediate pulley is generally screwed to the case that also serves as the pump housing. However, when the support shaft of the intermediate pulley is attached to the case that also serves as the pump housing in this way, the rigidity of this type of case is not sufficient because it is usually made of a light alloy. Of the intermediate pulley and the accuracy of the axial distance between the intermediate pulley and the crank pulley are deteriorated. When the tilt of these pulleys becomes large, thrust acts to shift the belt in the front-rear direction, so that the flange provided on the crank pulley and the belt are strongly hit, and the life of the belt is significantly shortened. Further, in order to support the intermediate pulley by the case as described above, it is necessary to increase the rigidity of the supporting portion and the tightening rigidity with respect to the cylinder block, and the case is inevitably thick and large. It will be connected to things.

(Object of the Invention) The present invention has been made in view of the above problems, and prevents the intermediate pulley shaft center from collapsing in the timing belt drive mechanism, and the accuracy of the axial distance between the intermediate pulley and the crank pulley. It is an object of the present invention to provide a belt pulley fixing structure for an engine that enhances the engine speed and enables the case that forms the timing belt chamber that also serves as the pump housing to be made compact.

(Structure of the Invention) The present invention increases the support rigidity of the intermediate pulley by directly fixing the intermediate pulley in the timing belt mechanism to the cylinder block with high rigidity via the case that also serves as the pump housing, and also by co-fastening. The case is made compact and the fastening rigidity with respect to the cylinder block is improved, and its configuration is as follows. That is, the belt pulley fixing structure for an engine according to the present invention is an engine in which a case forming a timing belt chamber that also serves as a pump housing is fastened to an end face of a cylinder block in the cylinder row direction.
It is characterized in that a mounting seat surface of an intermediate pulley arranged between the crank pulley and the cam pulley is formed, and the intermediate pulley is directly fastened to the cylinder block via the case.

(Function) The intermediate pulley has sufficient mounting rigidity because the mounting seat surface is formed in the case that doubles as the pump housing, and the supporting shaft penetrates through the case and is fastened to the highly rigid cylinder block. To be done. Therefore, although the protrusion length from the fixing point to the cylinder block to the point where the belt tension acts is long, the tilt of the pulley shaft core can be reduced. Further, since the support shaft of the intermediate pulley is fixed to the cylinder block, the accuracy of the axial distance between the crank pulley on the crankshaft positioned on the main bearing portion of the same cylinder block and the intermediate pulley is improved. Further, since the intermediate pulley penetrates the case and is attached to the cylinder block, the case itself can be formed compact, and the rigidity of the case is improved by jointly tightening the intermediate pulley.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a sectional view of FIG. 1 seen from the direction AA.

In this embodiment, a crankcase cover 2 is attached to the end surface of the cylinder block 1 in the lower cylinder row direction. A crank pulley 4 is attached to a protruding portion of a crank shaft 3 which penetrates the crank case cover 2 and protrudes to the front side, and a damper pulley 5 is arranged on the tip side of the crank pulley 4. 4,5
Are fastened together by fixing bolts 6. A flange portion 4a is integrally formed at an end portion of the crank pulley 4 on the engine body side, and a plate member 7 constituting the other flange portion is sandwiched between the other end portion of the crank pulley 4 and the damper pulley 5. It is worn.

Further, a case 8 forming a timing belt chamber is mounted on the end surface of the cylinder block 1 above the mounting position of the crankcase cover 2. The case 8 also serves as a pump housing, and a bearing portion 10 for supporting an impeller shaft 9 of a water pump is formed on one side of the case 8. The bearing portion 10 has radial ribs extending toward the outer periphery of the pump housing portion. 11 is provided. A plurality of boss portions 12 for fixing the case 8 to the cylinder block by bolts and enhancing the sealing performance of the pump chamber are formed on the outer peripheral edge of the pump housing portion. In addition, at the tips of the two ribs on the side, a boss portion 13 for attaching an auxiliary machine is provided.
Are formed. An idler pulley 14 is arranged on the upper side and a tensioner pulley 15 is arranged on the lower side at positions diagonally above and below the case 9. Further, two cam pulleys 17 and 18 on the intake cam side and the exhaust cam side are provided on the upper end surface of the cylinder head 16, and one timing belt 19 is provided between the cam pulleys 17 and 18 and the crank pulley 4. It is stretched. The idler pulley 14 is on the tension side of the timing belt 19 and contacts the timing belt 19 from the outside. Further, the tensioner pulley 15 is on the loose side of the timing belt, is eccentrically supported, and is urged by the spring 20 to also come into contact with the timing belt 19 from the outside. Case 9
Further, the crankcase cover 2 is formed with mating surfaces 21 and 22 of the belt covers so as to surround these two intermediate pulleys and the timing belt.

As shown in FIG. 2, the idler pulley 14 has a non-rotating portion 23 positioned on a mounting seat surface 24 formed on the case 9, and is fixed to the cylinder block 1 by a fixing bolt 25 penetrating the case 9. There is. As described above, since the non-rotating portion 23 of the idler pulley 14 is fixed to the cylinder block 1 by the fixing bolt 25 penetrating the case 8, the supporting rigidity is high, and therefore, the fall due to the belt tension is suppressed to be small. Further, since both the idler pulley 14 and the crankshaft 3 are fixed or axially supported by the cylinder block 1, it is easy to ensure the accuracy of the axial distance between the idler pulley 14 and the crankshaft 3.

The case 8 has a boss portion 12 on the pump housing portion side.
Besides, another boss portion 26 is provided on the opposite side. Then, the case 8 is fastened to the cylinder block 1 by bolts 27 penetrating the boss portions 12 and 26. Further, the case 8 has a shape in which it is fastened together with the idler pulley 14 by the fixing bolt 25, so that higher fastening rigidity can be obtained.

In addition, in this embodiment, the idler pulley is fixed to the cylinder block directly through the case as described above, but in addition to this idler pulley,
The tensioner pulley can be directly fixed to the cylinder block via the case. Of course, a structure in which only the tensioner pulley is fixed to the cylinder block is also possible. In particular, when both the idler pulley and the tensioner pulley arranged diagonally are directly attached to the cylinder block via the case in this way, the diagonal co-fastening effect further enhances the rigidity of the case, and consequently The supporting rigidity of the pulley is also improved.

(Effect of the Invention) Since the present invention is configured as described above, it is possible to prevent the intermediate pulley shaft center from falling in the timing belt drive mechanism and to improve the accuracy of the axial distance between the intermediate pulley and the crank pulley. You can Also, by tightening together,
It is possible to reduce the size of the case that forms the timing belt chamber that also serves as the pump housing and increase the rigidity thereof.

[Brief description of drawings]

FIG. 1 is an overall view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1: Cylinder block, 4: Crank pulley, 8: Case, 14: Idler pulley, 15: Tensioner pulley, 17, 18: Cam pulley, 19: Timing belt, 25: Fixing bolt.

Claims (1)

[Scope of utility model registration request] 1. An engine in which a case forming a timing belt chamber that also serves as a pump housing is fastened to an end surface of a cylinder block in the cylinder row direction, the case including:
A belt pulley fixing structure for an engine, characterized in that an attachment seat surface of an intermediate pulley arranged between a crank pulley and a cam pulley is formed, and the intermediate pulley is fastened directly to the cylinder block via the case. .