JPS6327173Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention adjusts the tension of the timing belt for transmitting the rotation of the crankshaft in an internal combustion engine to the camshaft for opening and closing intake valves and exhaust valves. It relates to a device for.

[Conventional technology]

This type of timing belt uses a toothed belt, but if this timing belt is loose, the meshing of the teeth will skip, causing a phase shift in synchronous transmission from the crankshaft to the camshaft. Therefore, it is necessary to apply appropriate tension to this timing belt.

For this reason, conventionally, a tension adjustment device such as that described in Japanese Utility Model Publication No. 58-5149 has been used for this timing belt. In other words, in this conventional tension adjustment device, a tension adjustment pulley that contacts the timing belt is attached to a substantially triangular support plate that is rotatably supported by a pin to a cover case that houses the timing belt. The support plate is configured to be fixed to the cover case with bolts, and a tension spring is installed between the support plate and the cover case to bias the tension adjustment pulley in the direction of the timing belt. Then, by loosening the bolt for fixing the support plate to the cover case, the tension adjustment pulley is pressed against the timing belt by the tension spring force, and a predetermined tension is applied to the timing belt. Later, the bolts were tightened to fix the support plate unrotatably.

[Problem that the invention attempts to solve]

However, in this conventional tension adjustment device, the tension adjustment pulley is rotatably pivoted to the cover case with a pin, and is supported in a substantially triangular shape that is fixed unrotatably with a bolt. Since it is attached to a plate and a tension spring is attached to this support plate, in addition to the large number of parts, the support plate becomes large and the installation space and weight increase. The tension spring used here may break due to the intense vibrations of the internal combustion engine, or
Alternatively, there have been frequent accidents in which the tension spring becomes disengaged from the support plate or the cover case and falls off, damaging the timing belt. Another problem is that when tightening the bolts after applying a predetermined tension to the timing belt, a special tool must be used with a regulated tightening torque so that the tension of the timing belt does not change due to this tightening. It was hot.

The present invention aims to solve this problem.

[Means for solving problems]

Therefore, the present invention provides a tension adjustment device in which a tension adjustment pulley is in contact with a timing belt wound between a crankshaft and a camshaft in an internal combustion engine, in which the tension adjustment pulley is formed in a cylindrical shape. The support plate is rotatably fitted onto the outer periphery of the support plate, while the support has a mounting hole parallel to the axis of the tension adjustment pulley at a position offset by an appropriate distance from the center of the tension adjustment pulley. A bolt is drilled and rotatably inserted into the mounting hole, and is screwed into the cylinder block or cylinder head of the internal combustion engine. An adjustment screw that presses the tension adjustment pulley against the timing belt, and the axis of the adjustment screw is aligned with the line connecting the tension adjustment pulley's contact point with the timing belt and the rotation center of the tension adjustment pulley. The structure is such that they are screwed together in a direction inclined at an appropriate angle.

〔Example〕

The following drawings show examples of the present invention (Figures 1 to 3).
To explain this, 10 in the figure indicates the main drive pulley 12 and the camshaft 13 on the crankshaft 11.
A timing belt is wound around the upper driven pulley 14, 15 is a cover case that covers the entire timing belt 10, and 16 is the crankshaft 11.
The tension adjustment pulleys in contact with the outer surface of the timing belt 10 are shown between the main drive pulley 12 and the driven pulley 14 on the camshaft 13 at the top, and the cover case 15 is a cylinder block or cylinder in an internal combustion engine. It is attached to the cylinder block and cylinder head separately from the head, or it is molded integrally with the cylinder block and cylinder head. The tension adjustment pulley 16 is formed into a cylindrical shape, and is rotatably fitted on the outer periphery of a disk-shaped support 17 via a ball bearing 18.
, the rotation center point O of the tension adjustment pulley 16
Mounting hole 19 at a position eccentrically eccentric by an appropriate distance e from
is drilled parallel to the axis of the pulley 16, and a bolt 20 with a head 20a is rotatably inserted into the mounting hole 19.
b is screwed into the female threaded hole 21 in the cylinder block integrally formed with the cover case 15, while the cover case 15 has a comparative part for pressing the tension adjustment pulley 16 in the direction of the timing belt 10. An adjustment screw 22 with a head 22a having a narrow diameter is connected to the timing belt 10 of the tension adjustment pulley 16 so that the axis 22b of the adjustment screw is connected to the timing belt 10 of the tension adjustment pulley 16.
The tension adjustment pulley 16 is screwed in a direction inclined at an appropriate angle θ with respect to a line 23 connecting a contact point S with the rotation center point O of the tension adjustment pulley 16.

In this configuration, in order to set the tension of the timing belt 10, after loosening the bolt 20 while the internal combustion engine is stopped, pinch the head 22a of the adjustment screw 22 with your fingertips and turn it.
The tension adjustment pulley 16 is pressed against the timing belt 10 to apply a predetermined tension to the timing belt 10.

When a predetermined tension is applied to the timing belt 10 in this manner, the support body 17 is fixed to the cover case 15 in an unrotatable manner by tightening the bolt 20.
0, the tension adjustment pulley 16 is in contact with the adjustment screw 22, and the tension adjustment pulley 16 is held so as not to be displaced by the tightening of the bolt 20. When tightening the bolt 20, there is no need to use a special tool that regulates the tightening torque as in the conventional method, and after tightening the bolt 20, turn the adjusting screw 22 in the opposite direction to adjust the tension. Either keep it away from the adjustment pulley 16 or remove it from the cover case 15 (note that after the adjustment screw 22 is removed from the cover case 15, the female screw hole is plugged with a rubber plug (not shown). ), and while the internal combustion engine is in operation, the support body 17 remains unrotatably fixed to the cover case 15 by tightening the bolts 20 in this manner.

Further, when setting the tension by turning the adjustment screw 22, the axis of the adjustment screw 22 is aligned with the timing belt of the tension adjustment pulley 16, as shown by the two-dot chain line in FIG. 1
When screwed together in the same direction as the line 23 connecting the contact point S with respect to 0 and the rotation center point O of the tension adjustment pulley 16, the pressing force of the adjustment screw 22 against the tension adjustment pulley 16 F0 is the timing belt 1 of the tension adjustment pulley 16.
Since it acts as a pressing force F1 against 0, the pressing force F0 by turning the adjustment screw 22 is
When ±ΔF changes, the pressing force F1 of the pulley 16 against the timing belt 10 also changes by the same amount ±ΔF.
The variation in the pressing force F0 caused by changing by ΔF and turning the adjustment screw 22 directly becomes a variation in the pressing force F1 on the timing belt 10, which in turn causes variation in the tension of the timing belt 10. By this, the timing belt 10
It becomes difficult to adjust the tension to a predetermined value.

Therefore, in the present invention, the adjustment screw 22 is connected to the axis 22b of the adjustment screw to the tension adjustment pulley 16.
A line 23 connecting the contact point S with respect to the timing belt 10 and the rotation center point O of the tension adjustment pulley 16
With this structure, the pressing force F0 of the adjustment screw 22 against the tension adjustment pulley 16 is attenuated by cos θ, and the timing belt 10 In other words, the pressing force F1 of the tension adjustment pulley 16 against the timing belt 10 is transmitted to
is F1=F0×cosθ, so F0 is ±
Even if ΔF changes, this amount of change ±ΔF will be attenuated by cos θ and will appear in the pressing force F1 against the timing belt 10, which is due to variations in the pressing force F0 due to turning the adjustment screw 22. This makes it possible to reduce the variation in the pressing force F1 applied to the timing belt 10.

[Functions and effects of the idea]

As described above, in the present invention, a pulley for tension adjustment is formed into a cylindrical shape and rotatably fitted on the outer periphery of a support, and a bolt rotatably inserted into a mounting hole of the support is attached to a cover case. It is attached by screwing together, and the tension adjustment pulley is pressed against the timing belt by an adjustment screw screwed into the cover case, and it is different from the conventional large triangular shape. Since a supporting plate and a tension spring are not required, the number of parts is reduced and the structure is extremely simple, making it possible to provide the engine at a low cost, reducing the installation space and reducing the weight of the internal combustion engine.

Moreover, the adjustment screw is screwed in a direction in which the axis of the adjustment screw is inclined by an appropriate angle with respect to a line connecting the contact point of the tension adjustment pulley with the timing belt and the rotational center point of the tension adjustment pulley. By adopting the configuration, it is possible to reduce the width of variation in the pressure force of the tension adjustment pulley against the timing belt due to variation in the pressure force against the tension adjustment pulley due to turning the adjustment screw. Therefore, the tension of the timing belt can be easily adjusted to approximately a predetermined value using the adjustment screw.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall view, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is an enlarged view of the main part of FIG.
FIG. 10...Timing belt, 11...Crankshaft, 13...Camshaft, 15...Cover case, 1
6...Tension adjustment pulley, 17...Support, 18
... Ball bearing, 19 ... Mounting hole, 20
...Bolt, 21...Adjustment screw.

Claims (1)

[Scope of utility model registration request] In a tension adjustment device in which a tension adjustment pulley is in contact with a timing belt wound between a crankshaft and a camshaft in an internal combustion engine, the tension adjustment pulley is formed in a cylindrical shape and the outer periphery of the support is A mounting hole is formed in the support body at a position eccentric from the rotation center of the tension adjustment pulley by an appropriate distance and parallel to the axis of the tension adjustment pulley. A bolt rotatably inserted into a mounting hole is screwed into a member such as a cylinder block or cylinder head in an internal combustion engine, while the tension adjustment pulley is attached to a cover case for a cylinder block or cylinder head or a timing belt in an internal combustion engine. the adjustment screw that presses against the timing belt,
An internal combustion engine characterized in that the axis of the adjustment screw is screwed in a direction inclined at an appropriate angle with respect to a line connecting the contact point of the tension adjustment pulley with the timing belt and the rotation center of the tension adjustment pulley. timing belt tension adjustment device.