JPH04262154A - Wrapping transmission device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve durability and restrain noise occurrence with the tension of an endless forwarding body retained always constant by oscillating an oscillation supporting member in a required direction with a temperature sensing element actuated when the tension of the endless forwarding body varies following the temperature variation of an internal combustion engine. CONSTITUTION:A tensioner body 13 and a tensioner pulley boss 15 are oscillated respectively in a clockwise direction with a bolt 11 as a center, in a condition where a notch 16 is abutted to the movable protruded shaft part 18 of a thermostat 17 with a return spring 24. Consequently a toothed belt is stretched, and crank shaft power is transmitted to respective cam shafts of intake and exhaust valves respectively in operating an internal combustion engine. A temperature rise in the internal combustion engine causes increasing inter-shaft distances of the crank shaft and respective cam shafts of the intake and exhaust valves. At that time, the thermostat 17 is actuated to protrude the movable protruded shaft part 18 to rotate the said pulley boss 15 in an counterclockwise direction. Consequently the increase of the tension of the toothed belt, following the increase of the said inter-shaft distances, can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrap transmission device for an internal combustion engine that transmits power by using an endless conveying body such as an endless belt or an endless chain that spans a crankshaft and a valve train.

0002

[Prior art and problems to be solved] In an aluminum alloy internal combustion engine using a timing belt in the valve train,
The thermal expansion coefficient of aluminum alloy is larger than that of the timing belt (approximately 5 times), so when an internal combustion engine is operating, the distance between the shafts of the valve train increases significantly relative to the elongation of the timing belt, and the timing A large tension force was generated in the belt, reducing its durability, and the teeth of the timing belt were forced to mesh with the teeth of the pulley, producing noise.

0003

[Means and effects for solving the problems] The present invention relates to an improvement of a wrap-around transmission for an internal combustion engine that overcomes the above-mentioned difficulties. The wrap transmission device that transmits power from the drive shaft to the driven shaft includes a tensioner body attached to the internal combustion engine body, and a oscillator pivotally supported on the tensioner body so as to be swingable along the feeding surface of the endless feeding body. a dynamic support member; a spring member that presses a contact portion of the swinging member against the endless feeding body to apply tension to the endless feeding body; and a change in the degree of tension of the endless feeding body due to a change in temperature of the internal combustion engine. The present invention is characterized in that it includes a temperature sensing element that swings the swinging support member in a direction that cancels out.

[0004] Since the present invention is configured as described above, even when the internal combustion engine starts operating and the tension of the endless conveying body is about to change due to a change in the temperature of the internal combustion engine, the temperature sensing element does not operate. Then, the swing support member swings in a direction that cancels out the change in the tension, and the tension of the endless feeding body is maintained substantially constant.

The present invention also provides a belt transmission device that spans an endless belt between a drive pulley and a driven pulley of an internal combustion engine and transmits power from the drive pulley to the driven pulley. , a tensioner pulley boss pivotally supported on the tensioner main body so as to be able to swing along the feeding surface of the endless belt; and a tensioner pulley rotatably fitted to the tensioner pulley boss so as to be able to contact the endless belt. , a return spring that presses the tensioner pulley against the endless belt to apply tension to the endless belt; and a return spring that overcomes the spring force of the return spring as the temperature of the internal combustion engine increases and swings the tensioner pulley boss. With this configuration, even if the tension of the endless belt increases due to a rise in the temperature of the internal combustion engine, the operation of the temperature sensing element will prevent the tension from increasing. The tensioner pulley boss swings by overcoming the spring force of the return spring, and the tension of the endless belt is loosened, so that the tension is maintained at a substantially constant level.

Further, the present invention provides a chain transmission device that spans an endless chain between a driving sprocket and a driven sprocket of an internal combustion engine to transmit power from the driving sprocket to the driven sprocket, which includes a tensioner body attached to the internal combustion engine body; , a slipper pivotally supported on the tensioner body so as to be swingable along the feeding surface of the endless chain;
a spring member that presses a contact portion of the slipper against the endless chain to apply tension to the endless chain; and a spring member that swings the slipper in a direction to cancel changes in the tension of the endless chain due to temperature changes of the internal combustion engine. With this structure, even if the tension of the endless chain changes due to a rise in the temperature of the internal combustion engine, the operation of the temperature sensing element will not change. The slipper swings in a direction that cancels out the change in tension,
The tension of the endless chain is maintained substantially constant.

[0007]

[Embodiment] An embodiment of the present invention illustrated in FIGS. 1 to 4 will be described below.

The internal combustion engine 1 is the V-type four-cylinder four-stroke internal combustion engine mounted on a motorcycle (not shown), and
Two drive toothed pulleys 3 are integrally arranged on the left end of the crankshaft 2 (on the near side in FIG. 1) and arranged in the axial direction.

Further, an intake valve camshaft 5 and an exhaust valve camshaft 6 are respectively rotatably supported at the tops of the front and rear cylinders 4 so as to be oriented in the vehicle width direction. A driven toothed pulley 7 and a driven toothed pulley 8 are each integrally fitted to the left end.

Furthermore, a protrusion 10 for supporting the tensioner pulley 9 is protrudingly provided approximately at the center of the cylinder 4 along the rotational surfaces of the drive toothed pulley 3, driven toothed pulley 7, and driven toothed pulley 8. A tensioner body 13 and a tensioner pulley boss 15 are rotatably attached to a bolt 11 screwed into the bolt 11 via a sleeve 12, and a mounting pin 1 is attached to the inner surface of the tensioner body 13.
4 is provided protrudingly.

Furthermore, a notch 16 is formed in the tensioner pulley boss 15 so that the tensioner body 13 can swing within a predetermined range and a thermostat 17 passing through the tensioner body 13 can move in response to the swinging of the tensioner body 13. , tensioner pulley boss 15
A tensioner pulley 9 is rotatably fitted on the outer periphery of the tensioner pulley 9 via a ball bearing 19. Note that clip 20
Tensioner pulley 9 is tensioner pulley boss 15
This is to fix it so that it does not move in the axial direction.

Further, a toothed belt 21 is spanned between the drive toothed pulley 3 and the driven toothed pulleys 7 and 8, and a tensioner pulley 9 is brought into contact with the back surface of the toothed belt 21, applying tension to the toothed belt 21. As shown in FIG. 1, a spring 22 that swings the tensioner body 13 clockwise about the bolt 11 is stretched between the mounting pin 14 of the tensioner body 13 and the cylinder 4.

Furthermore, a coiled return spring 24 is wound around the bolt 11 via a winding element 23.
One end of the return spring 24 is the tensioner body 1
3, and the other end of the return spring 24 is engaged with the tensioner pulley boss 15, so that the tensioner pulley boss 15 swings clockwise about the bolt 11 by the spring force of the return spring 24. is energized by

Furthermore, a spring 25 loosely fitted into the cylindrical portion of the thermostat 17 is interposed between a serp clip 26 engaged with the cylindrical portion of the thermostat 17 and the tensioner body 13, and the spring force of the surp clip 26 is This allows the large diameter portion of the thermostat 17 to be in constant contact with the tensioner body 13.

Since the embodiment shown in FIGS. 1 to 4 is constructed as described above, the end surface of the notch 16 comes into contact with the tip of the movable protruding shaft portion 18 of the thermostat 17 due to the spring force of the return spring 24. With the spring 2
Due to the spring force of 2, the tensioner body 13 swings clockwise around the bolt 11, and the tensioner pulley boss 15 also swings in the same direction, and a constant tension force acts on the toothed belt 21, causing the internal combustion engine 1 to operate. When the power of the crankshaft 2 is transmitted to the intake valve camshaft 5 and the exhaust valve camshaft 6
will be reliably communicated.

When the temperature inside the internal combustion engine 1 increases as time passes after the internal combustion engine 1 is started, the cylinder block and cylinder head of the internal combustion engine 1 made of aluminum alloy expand, and the toothed belt 21 The distance between the crankshaft 2, intake valve camshaft 5, and exhaust valve camshaft 6 increases significantly compared to the elongation of .

However, even if the distance between the crankshaft 2, the intake valve camshaft 5, and the exhaust valve camshaft 6 increases significantly compared to the elongation of the toothed belt 21, as shown in FIG. is activated by the temperature rise in the internal combustion engine 1, the movable protruding shaft portion 18 protrudes, and the toothed belt 2
The tensioner pulley boss 15 rotates counterclockwise around the bolt 11 so that the tension on the crankshaft 2, intake valve camshaft 5, and exhaust valve camshaft 6 is loosened by increasing the distance between the shafts. An increase in the tension force of the belt 21 is prevented, and the tension state of the toothed belt 21 is maintained constant regardless of temperature changes in the internal combustion engine 1.

This prevents noise from being generated when the teeth of the toothed belt 21 mesh with the teeth of the crankshaft 2, intake valve camshaft 5, and exhaust valve camshaft 6 due to excessive tension. The durability of the toothed belt 21 is greatly improved.

In the embodiment shown in FIGS. 1 to 4, the thermostat 17 is used as the temperature sensing element, but as shown in FIG. A coiled shape memory alloy spring 28 is inserted into the notch 16b on the left side of the protruding piece 13a and expands due to temperature rise, with the return spring 27 interposed therein.
The embodiment shown in FIG. 5 may also have the same effect as the embodiment shown in FIGS. 1 to 4.

Furthermore, as shown in FIG. 6, the present invention can be applied to a chain transmission instead of a belt transmission.

That is, the drive sprocket 30 is fitted to the crankshaft 2, and the intake valve camshaft 5
, a driven sprocket 31 on the exhaust valve camshaft 6,
32 respectively, and these drive sprockets 3
0, an endless chain 33 made of steel is bridged between the driven sprockets 31 and 32, and a tensioner body 35 is oscillated between the drive sprocket 30 and the driven sprocket 32, adjacent to the drive sprocket 30, and connected to the internal combustion engine 1 via a bolt 34. Tensioner body 3 is pivoted for free movement.
A mounting pin 36 is integrally protruded from the mounting pin 36, and a spring 38 for biasing the mounting pin 36 clockwise is interposed between the mounting pin 36 and the internal combustion engine 1.

[0022] And the protrusion 37 of the tensioner body 35
A slipper 39 having a notch 40 into which it can be loosely fitted is pivotally attached to the bolt 34, and a return spring (not shown) that biases the slipper 39 clockwise is attached to the tensioner body 35 and the slipper 39. The protruding piece 37 of the tensioner body 35 passes through the movable protruding shaft portion 18 of the thermostat 17, and the tip of the movable protruding shaft portion 18 is brought into contact with the end surface of the notch 40.

In the chain transmission device constructed as described above, even if the coefficient of thermal expansion of the internal combustion engine 1 made of aluminum alloy is larger than that of the endless chain 33 made of steel, the difference in elongation causes the difference in the coefficient of thermal expansion of the endless chain 33. The increase in tension is prevented,
It is possible to improve the durability of the endless chain 33 and prevent noise.

[0024]

[Effects of the Invention] In this way, in the present invention, the tension of the endless conveying body such as an endless belt or an endless chain is maintained approximately constant, so the durability of the endless conveying body is improved and noise generation is suppressed. Ru.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of a wrap-around transmission device for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged front view of the main part thereof.

FIG. 3 is an enlarged front view of main parts in a high temperature state in FIG. 2;

FIG. 4 is a longitudinal side view taken along line IV-IV in FIG. 2;

FIG. 5 is an enlarged front view of main parts of another embodiment.

FIG. 6 is a front view of yet another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Internal combustion engine, 2...Crankshaft, 3...Drive toothed pulley, 4...Cylinder, 5...Intake valve camshaft, 6...Exhaust valve camshaft, 7, 8...Driven toothed pulley, 9...Tensioner pulley, 10 ...Protrusion, 11...Bolt, 12...
Sleeve, 13...Tensioner body, 14...Mounting pin, 15...Tensioner pulley boss, 16...Notch, 1
7...Thermostat, 18...Movable protruding shaft portion, 19...Ball bearing, 20...Clip, 21...Toothed belt, 22
... Spring, 23 ... Winding element, 24 ... Return spring, 25 ... Spring, 26 ... Surp clip, 27 ... Coiled return spring, 28 ... Coiled shape memory alloy spring, 30 ... Drive sprocket, 31, 32 ... Driven sprocket , 33... Endless chain, 34... Bolt, 35... Tensioner body, 36
...Mounting pin, 37...Protrusion piece, 38...Spring, 39...
Slipper, 40...notch.

Claims (3)

[Claims] 1. A tensioner main body attached to an internal combustion engine main body in a wrap transmission device that spans an endless feeding body between a drive shaft and a driven shaft of an internal combustion engine and transmits power from the drive shaft to the driven shaft; A swinging support member pivotally supported on the tensioner body so as to be able to swing freely along the feeding surface of the endless feeding body and a contact portion of the swinging member are pressed against the endless feeding body to apply tension to the endless feeding body. and a temperature sensing element that swings the swinging support member in a direction that cancels a change in the tension of the endless feeding body due to a temperature change in the internal combustion engine. Wrap transmission device. 2. A belt transmission device that transmits power from the drive pulley to the driven pulley by extending an endless belt between a drive pulley and a driven pulley of an internal combustion engine, comprising: a tensioner body attached to the internal combustion engine body;
a tensioner pulley boss pivotally supported on the tensioner main body so as to be able to swing along a feeding surface of the endless belt; a tensioner pulley rotatably fitted to the tensioner pulley boss so as to be able to contact the endless belt; a return spring that presses the tensioner pulley against the endless belt to apply tension to the endless belt; and a return spring that presses the tensioner pulley against the endless belt and applies tension to the endless belt; A belt transmission device for an internal combustion engine, characterized by comprising a sensing element. 3. A chain transmission device that spans an endless chain between a driving sprocket and a driven sprocket of an internal combustion engine to transmit power from the driving sprocket to the driven sprocket, the chain transmission device comprising: a tensioner main body attached to an internal combustion engine main body; a slipper pivotally supported on the tensioner main body so as to be able to swing along a feeding surface of the internal combustion engine; a spring member that presses a contact portion of the slipper against the endless chain to apply tension to the endless chain; A chain transmission device for an internal combustion engine, comprising: a temperature sensing element that swings the slipper in a direction that cancels a change in the tension of the endless chain due to a temperature change.