JP2018131955A - Timing belt system of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower friction in cold start by preventing excessive adherence of a lubricant to a timing belt and a sprocket.SOLUTION: In a timing belt system of an engine in which a timing belt is wound on a crank sprocket disposed at a crank shaft of an engine and a cam sprocket 5 disposed at a cam shaft 11, and power is transmitted between the crank shaft and the cam shaft 11 in an environment in which a lubricant flows into a space in which the crank sprocket, the cam sprocket 5 and the timing belt exist, a discharge port 33 is formed to discharge the lubricant from a tooth bottom portion 32 between a tooth portion 31 and a tooth portion 31 of the cam sprocket 5, and the lubricant discharged from the discharge port 33 is discharged while avoiding a moving position of the timing belt by a guide portion 40.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a lubrication technique in an engine timing belt system.

Timing chains and timing belts are often used as means for transmitting driving force from a crankshaft of an engine used in a vehicle or the like to a camshaft.
Among them, the timing belt is made of, for example, resin, and generally has low noise compared to the timing chain, but has low durability and may need to be replaced after a long period of operation.

  Patent Document 1 discloses an example of a timing belt system that is a camshaft drive system using a timing belt. The timing belt system of Patent Document 1 includes sprockets at one end of a camshaft projecting from the side surface of the engine body and one end of the crankshaft, and the timing belt is wound around these sprockets to rotate the crankshaft. Along with this, the camshaft is rotated. Further, a cover that covers the sprocket and the timing belt is provided on a side surface of the engine body.

  In recent years, in the timing belt system, a technique for using a timing belt and a sprocket in a space where lubricating oil flows has been developed.

JP-A-9-250355

  However, if the timing belt and sprocket are used in the space where the lubricating oil flows as described above and the lubricating oil is supplied to the meshing portion of the timing belt, the temperature of the lubricating oil is, for example, as during cold start. If the viscosity of the lubricating oil adhering to the timing belt or sprocket increases and the frictional force between the timing belt and sprocket increases, the life of the timing belt decreases, or the timing belt tooth surface If there is a cold lump of lubricating oil, the meshing with the sprocket becomes irregular, which may cause timing belt breakage or tooth skipping.

  The present invention has been made to solve such problems, and an object of the present invention is to prevent excessive adhesion of lubricating oil to the timing belt and the sprocket in the engine timing belt system, thereby cooling the engine. It is to reduce the friction at the start of the state.

  In order to achieve the above object, an engine timing belt system according to the present invention includes a crank sprocket provided on a crankshaft of an engine and a cam sprocket provided on a camshaft. A timing belt system for an engine that transmits power between the crankshaft and the camshaft in an environment where lubricating oil flows into a space where the cam sprocket and the timing belt exist, and is in contact with the timing belt The rotating part is provided with an oil discharge means for guiding the lubricating oil adhering to the rotating part to the outside of the moving position of the timing belt to reduce the lubricating oil from the rotating part.

Preferably, the rotating component is a sprocket or a pulley having a tooth portion that meshes with the timing belt on an outer peripheral surface, and the oil discharging means removes lubricating oil from a tooth bottom portion between two adjacent tooth portions. It is good to have a discharge port to discharge.
Preferably, the oil discharge means includes a guide member that is disposed closer to the shaft core side of the rotating component than the discharge port and guides the lubricating oil discharged from the discharge port. It is preferable that the lower end portion of the guide member protrudes outward from the moving position of the timing belt.

Preferably, a groove that is arranged on the outer peripheral surface of the pulley that supports the back surface of the timing belt so as to incline in the vertical direction and guides the lubricating oil adhering to the pulley outward in the width direction of the pulley. It is good to provide.
Preferably, the tooth portion of the timing belt and the tooth portion of the contact member meshing with the tooth portion extend in the width direction while being inclined in the extending direction of the timing belt, and the tooth portion of the timing belt is in the vertical direction. It is good to arrange so that it may incline.

  According to the timing belt system of the engine of the present invention, the lubricating oil adhering to the rotating part is guided to the rotating part that contacts the timing belt to the outside of the moving position of the timing belt, and the lubricating oil is supplied from the rotating part. Since the oil discharging means for reducing is provided, it is possible to operate the engine by reducing the lubricating oil adhering between the timing belt and the rotating parts. Therefore, even when the viscosity of the lubricating oil increases in a low temperature environment, the sliding resistance when driving the timing belt can be suppressed. Thereby, the load of a timing belt can be suppressed and the lifetime of a timing belt can be improved.

It is a perspective view showing a schematic structure of a timing belt system of an embodiment of the present invention. It is a side view of the engine which shows the structure of the timing belt system in this embodiment. It is a perspective view which shows the shape of the tooth | gear part in the cam sprocket of this embodiment. It is sectional drawing of the tooth bottom part of the cam sprocket of this embodiment. It is a front view of the cam sprocket in this embodiment. It is a longitudinal cross-sectional view of the cam sprocket in this embodiment. It is a side view of the tensioner pulley in this embodiment. It is a figure which shows the shape of the tooth | gear part inside the timing belt in this embodiment.

Hereinafter, an embodiment of an engine timing belt system embodying the present invention will be described.
An engine 1 to which the timing belt system 2 of the present embodiment is applied is, for example, a travel drive engine mounted on a vehicle.
FIG. 1 is a perspective view showing a schematic structure of a timing belt system 2 of an engine 1 according to an embodiment of the present invention. In this figure, the attachment state of the timing belt 3 and the timing belt cover 4 is shown. FIG. 2 is a side view of the engine 1 showing the structure of the timing belt system 2 in the present embodiment.

  As shown in FIGS. 1 and 2, a timing belt system 2 is provided on a side surface of the engine 1. The timing belt system 2 includes a cam sprocket 5, a crank sprocket 6, idler pulleys 7 and 8, a tensioner pulley 9, and a timing belt 3. The cam sprocket 5, the crank sprocket 6, the idler pulleys 7 and 8, and the tensioner pulley 9 correspond to the rotating parts of the present invention.

  One end of the camshaft 11 protrudes from the side surface of the cylinder head 10 of the engine 1, and the cam sprocket 5 is fixed to one end of the camshaft 11. One end of a crankshaft 13 projects from the side surface of the cylinder block 12 of the engine 1, and the crank sprocket 6 is fixed to one end of the crankshaft 13. Further, idler pulleys 7 and 8 and a tensioner pulley 9 are rotatably supported on the side surface of the cylinder block 12.

An endless timing belt 3 is wound around the cam sprocket 5, the crank sprocket 6, the idler pulleys 7 and 8, and the tensioner pulley 9. The outer peripheral surface of the timing belt 3 is flat, and spline-like tooth portions 31 are formed on the inner peripheral surface.
Therefore, the rotation of the crankshaft 13 causes the camshaft 11 to rotate synchronously via the timing belt 3, thereby opening and closing an intake valve and an exhaust valve (not shown) disposed in the cylinder head 10.

  A timing belt cover 4 that covers the timing belt system 2 is provided on a side surface of the engine 1. The timing belt cover 4 is fixed to the cylinder head 10 and the cylinder block 12 by bolts 20 and seals an internal space in which the timing belt system 2 such as the cam sprocket 5, the crank sprocket 6 and the timing belt 3 is disposed.

In the present embodiment, the engine 1 is arranged such that the camshaft 11 and the crankshaft 13 extend horizontally.
Further, in the timing belt cover 4, for example, the lubricating oil that has risen into the cylinder head 10 of the engine 1 passes through the timing belt cover 4 and is returned to the oil pan 21.
FIG. 3 is a perspective view showing the shape of the tooth portion 31 in the cam sprocket 5 of the present embodiment. FIG. 4 is a sectional view of the tooth bottom portion 32 of the cam sprocket 5 of the present embodiment.

  As shown in FIG. 3, the cam sprocket 5 of the present embodiment is provided with a discharge port 33 (oil discharge means) for discharging the lubricating oil in each of the tooth bottom portions 32 between the adjacent tooth portions 31. For example, the discharge port 33 is disposed at an intermediate position in the circumferential direction of the cam sprocket 5 at the tooth bottom portion 32, and two discharge ports 33 are provided at intervals in the axial direction (width direction) of the cam sprocket 5. In addition, it is good to arrange | position the discharge port 33 for every tooth root part 32, shifting in the axial direction. For example, in FIG. 3, in two tooth bottom portions 32 adjacent to each other with the tooth portion 31, the discharge port 33 is disposed at the width position a in FIG. 3 in one tooth bottom portion 32, and in the other tooth bottom portion 32, A discharge port is disposed at a width position b in FIG.

Further, as shown in FIG. 4, the tooth bottom portion 32 is formed to be inclined toward the discharge port 33 in the axial direction of the cam sprocket 5.
FIG. 5 is a front view of the cam sprocket 5. FIG. 6 is a longitudinal sectional view of the cam sprocket 5.
As shown in FIGS. 5 and 6, the cam sprocket 5 of the present embodiment further includes a cylindrical guide portion 40 (guide member, oil discharging means) that guides the lubricating oil discharged from the discharge port 33 to the outside of the cam sprocket 5. )have.

  The guide portion 40 is provided closer to the shaft core side than the tooth bottom portion 32, and is arranged coaxially with the shaft core of the cam sprocket 5. The outer peripheral surface of the guide part 40 extends from the vicinity of the inner side surface 41, which is a side surface disposed on the engine side of the cam sprocket 5, while inclining toward the axial core side toward the outer side surface 42 on the opposite side. Further, the end portion 43 on the outer surface 42 side of the guide portion 40 protrudes outward in the axial direction from the outer surface 42 of the cam sprocket 5.

  The engine 1 of the present embodiment is arranged such that the camshaft 11 extends in the horizontal direction. Therefore, in the upper part of the cam sprocket 5, the guide portion 40 is located below the discharge port 33 on the outer surface 42 side of the cam sprocket 5. Inclined downward toward As a result, as indicated by the arrows in FIG. 6, the lubricating oil discharged downward from the discharge port 33 at the upper portion of the cam sprocket 5 falls to the outer peripheral surface of the guide portion 40 and travels along this inclined outer peripheral surface. Then, it flows to the outer surface 42 side and is discharged to the outside of the cam sprocket 5.

  Thereby, when the engine is stopped, the lubricating oil adhering to the meshing portion between the timing belt 3 and the cam sprocket 5 is discharged while avoiding the moving position of the timing belt 3. Therefore, the amount of lubricating oil adhering to the meshing portion between the timing belt 3 and the cam sprocket 5 is reduced. For example, in a cold region, even when the temperature of the lubricating oil decreases and the viscosity increases, The load on the timing belt 3 due to the lubricating oil can be reduced, and thus the life of the timing belt 3 can be extended.

  In FIG. 6, the guide portion 40 is formed integrally with the boss portion 44 into which the camshaft 11 is inserted, the tooth bottom portion 32, and the tooth portion 31, and between the boss portion 44 and the tooth portion 31. However, the guide portion 40 may be provided separately from the cam sprocket 5 and connected by, for example, a bolt or the like. In this way, the guide part 40 can be formed thin.

In addition, a rib extending in the axial direction may be appropriately provided on the outer peripheral surface of the guide portion 40 so that the lubricating oil that has dropped from the discharge port 33 to the outer peripheral surface on the upper side of the guide portion 40 flows to the outer surface 42 side.
Moreover, the guide part 40 does not need to be cylindrical, for example, the structure divided | segmented into the circumferential direction may be sufficient.

In the above embodiment, the present invention is applied to the cam sprocket 5, but it can also be applied to the idler pulley 7 disposed inside the crank sprocket 6 and the timing belt 3.
FIG. 7 is a side view of the tensioner pulley 9.
The outer peripheral surface 50 of the tensioner pulley 9 is a flat circumferential surface that matches the back surface of the flat timing belt 3.

As shown in FIG. 7, in this embodiment, a groove 51 (oil discharging means) for discharging the lubricating oil is further provided on the outer peripheral surface 50.
The groove 51 has a width and a depth of, for example, about several millimeters, and is provided so as to extend while being inclined in the circumferential direction from one end portion in the width direction of the outer peripheral surface 50 of the tensioner pulley 9 to the other end portion.
A plurality of grooves 51 are arranged on the outer peripheral surface 50 at equal intervals. The grooves 51 may be provided on the outer peripheral surface 50 at different intervals.

In addition to the tensioner pulley 9, the idler pulley 8 disposed outside the timing belt 3 and supporting the back surface of the timing belt 3 may be provided with a groove similar to that of the present embodiment.
As described above, the tensioner pulley 9 and the idler pulley 8 that support the back surface (outer surface) of the timing belt 3 are provided with the inclined grooves 51, and therefore, between the timing belt 3 and the pulleys 8 and 9. The lubricating oil flows downward along the groove 51 and is discharged outward from the outer end portions of these pulleys while avoiding the moving position of the timing belt 3.

Thus, when the engine is stopped, when the engine 1 is started in a state where the lubricating oil between the timing belt 3 and the pulleys 8 and 9 is discharged and the temperature of the lubricating oil decreases and the viscosity increases. The load on the timing belt 3 can be reduced.
FIG. 8 is a view showing the shape of the tooth portion 61 inside the timing belt 3.
As shown in FIG. 8, the tooth portion 61 inside the timing belt 3 of the present embodiment that meshes with the tooth portion 31 of the cam sprocket 5 is in the extension direction of the timing belt 3, that is, the moving direction of the timing belt 3. It is formed so as to be inclined in the extending direction from the vertical direction. Further, as the teeth 61 of the timing belt 3 are inclined, the teeth of the cam sprocket 5, the crank sprocket 6 and the inner idler pulley 7 that mesh with the teeth 61 are inclined.

Moreover, about the tooth | gear part 61 inside the timing belt 3, the intensity | strength is made higher in the site | part (c in the figure) of the timing belt moving direction ahead side than the moving direction back side. For example, the thickness of the tooth portion 61 may be increased by thickening the tooth cloth disposed inside the tooth portion 61.
In this way, by inclining the teeth 61 inside the timing belt 3, the lubricating oil adhering to the timing belt 3 flows to the lower end along the teeth 61, and from the timing belt 3. Is also discharged to the side. Thereby, the lubricating oil adhering to the timing belt 3 can be removed.

  Further, since the tooth portion 61 of the timing belt 3 is inclined with respect to the moving direction, when the tooth portion 61 of the timing belt 3 meshes with the tooth portion 31 of the crank sprocket 6 or the cam sprocket 5, Engage from the leading end C in the moving direction. Thus, at the beginning of meshing, only a part of the tooth portion 61 is meshed, so that a large load acts on the distal end portion C of the tooth portion 61 that is the meshing portion. In the present embodiment, since the strength of the distal end portion C in the moving direction of the tooth portion 61 is increased, the durability of the timing belt 3 can be appropriately improved.

The description of the embodiment is finished as above, but the aspect of the present invention is not limited to the above embodiment. For example, the inclination of the guide portion 40, the groove 51, and the tooth portion 61 of the timing belt 3 does not necessarily have to be adopted. However, it is desirable to provide the guide portion 40 according to the discharge port 33.
The present invention can be widely applied to a timing belt system of an engine that is lubricated with a lubricating oil.

1 Engine 2 Timing Belt System 3 Timing Belt 5 Cam Sprocket (Rotating Parts)
6 Crank sprocket (Rotating parts)
7 idler pulley (rotary parts)
8 idler pulley (rotary parts)
9 Tensioner pulley (Rotating parts)
31 Tooth part 32 Tooth bottom part 33 Discharge port (oil discharge means)
40 Guide part (guide member, oil discharge means)
51 grooves 61 teeth

Claims (5)

A timing belt is wound around a crank sprocket provided on an engine crankshaft and a cam sprocket provided on a camshaft, and lubricating oil flows into a space where the crank sprocket, the cam sprocket and the timing belt are present. An engine timing belt system for transmitting power between the crankshaft and the camshaft in an environment,
The rotating component that contacts the timing belt is provided with an oil discharging means that guides the lubricating oil adhering to the rotating component to the outside of the moving position of the timing belt to reduce the lubricating oil from the rotating component. A featured engine timing belt system. The rotating component is a sprocket or pulley having a tooth portion meshing with the timing belt on an outer peripheral surface,
2. The engine timing belt system according to claim 1, wherein the oil discharge unit has a discharge port for discharging lubricating oil from a tooth bottom portion between two adjacent tooth portions. The oil discharging means is
A guide member that is disposed closer to the axis side of the rotating component than the discharge port and guides the lubricating oil discharged from the discharge port;
The guide member is inclined in the vertical direction,
The engine timing belt system according to claim 2, wherein an end portion on a lower side of the guide member protrudes outward from a moving position of the timing belt.   The outer peripheral surface of the pulley that supports the back surface of the timing belt is disposed so as to be inclined in the vertical direction, and a groove that guides the lubricating oil adhering to the pulley outward in the width direction of the pulley is provided. The engine timing belt system according to any one of claims 1 to 3.   The tooth part of the timing belt and the tooth part of the contact member meshing with the tooth part extend in the width direction while inclining in the extending direction of the timing belt, and the tooth part of the timing belt is inclined in the vertical direction. The engine timing belt system according to any one of claims 1 to 4, wherein the engine timing belt system is arranged.

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