JPH08326852A - Timing adjusting device - Google Patents

Abstract

PURPOSE: To appropriately adjust the drive timing by providing an actuating mechanism for actuating a guide for a transmission member so as to adjust the transmission length in accordance with an atmospheric temperature, in a timing adjusting device for adjusting the tension of the transmission member wound on a winder. CONSTITUTION: A timing adjusting device 16 composed of a chain guide 18 as a transmission member guide, and a guide actuating mechanism 20 is provided for a timing chain 14 wound on a drive side timing sprocket 10 and a driven side timing sprocket 12 in an engine 2. The guide actuating mechanism 20 is composed of a temperature sensing element 26 and a spring 38, and presses the timing chain 14 from the outside by means of a pressing member 36 through a piston 46 since thermowax 44 in the temperature sensing element 36 expands when the atmospheric temperature of the engine 2 rises. With this arrangement, the path of the chain is shortened so as to absorb an elongation of the timing chain 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timing adjusting device, and more particularly to a timing adjusting device capable of holding drive timings of a driving side and a driven side at set values.

[0002]

2. Description of the Related Art In a valve operating system of a vehicle engine, a crank pulley or a crank sprocket, which is a driving side winding body provided on a crank shaft, and a cam pulley or a cam sprocket, which is a driven side winding body provided on a cam shaft, are provided. A timing belt or timing chain, which is a transmission tool, is wrapped around the
There is provided a timing adjusting device provided with a tensioner that adjusts the tension of the timing belt or the like to adjust the drive timing of the drive-side crankshaft and the driven-side camshaft.

That is, as shown in FIG.
Is composed of a cylinder block 204, a cylinder head 206, and a crankcase 208. Cylinder block 2
A drive side timing 210 is provided on a crank shaft (not shown) that is axially supported by 04, and a driven side timing sprocket 212 is provided on a cam shaft (not shown) of the cylinder head 206.
0 and the driven side timing sprocket 212 are wound around a timing chain 214, and a tensioner 218 as a timing adjusting device 216 is provided on the slack side of the timing chain 214 to apply an initial tension to the timing chain 214. .

Further, such a timing adjusting device is disclosed, for example, in Japanese Utility Model Laid-Open No. 59-77649. The one described in this publication is inserted into a sliding hole formed in the housing and is biased in the protruding direction and has a rack formed in the protruding direction, and is pivotally mounted in a groove formed in the housing. A ratchet that is biased by rotation to engage with the rack of the plunger and is restrained from rotating when the plunger retracts, and a bimetal member that prevents rotation of the ratchet accompanying advance of the plunger at a predetermined temperature are provided.
The tension of the timing belt caused by the temperature change is adjusted.

[0005]

However, in the conventional timing adjusting device, it is possible to solve the tension change of the timing chain or the like due to the change of the ambient temperature of the valve operating system of the engine. Due to a certain difference in coefficient of thermal expansion, the engine is at normal temperature (when it is cold)
Since the distance between the driving-side timing sprocket and the driven-side timing sprocket changed between the warm-up time and the warm-up time, it was not possible to correct the drive timing deviation between the driving side and the driven side.

For example, in the valve train of the engine 202 shown in FIG. 5, the tension side length 1 between the driving side timing sprocket 210 and the driven side timing sprocket 212 is set to 250 〓, and the cylinder block 204 and the cylinder head 206 are The material is aluminum,
If the timing chain 214 is made of iron, the cylinder block 2 can be used when the ambient temperature rises to 100 ° C.
04 side is 0.275 more than timing chain 214 side
〓 It will grow long. At this time, if the diameter of the drive-side timing sprocket 210 is set to 20 〓, there is a disadvantage that the drive timing is deviated by 1.79 ^O in crank angle. That is, in FIG. 5, since the timing chain 214 is extended to the slack side of the timing chain 214 as the temperature rises, and the cylinder block 204 side extends, the timing of the driven side timing sprocket 212 advances from the initial setting. It is a thing.

[0007]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention adjusts the tension of the transmission member wound around the driving-side winding body and the driven-side winding body to drive the same. In the timing adjusting device for adjusting the drive timing between the driving side and the driven side, a transmission guide that is in contact with the transmission is arranged on the tension side of the transmission, and the substantial length of the transmission according to the ambient temperature state. A guide actuating mechanism for actuating the transmission tool guide to adjust the above is provided.

[0008]

According to the structure of the present invention, since the transmission is extended to the tension side, even if a material having a large coefficient of thermal expansion is used for the cylinder block, the driven side winding body is driven at the same timing as the initial setting. Further, the impact load acting on the transmission at the time of startup is reduced by the guide actuation mechanism, and further, since the transmission guide is provided on the tension side of the transmission, vibration of the transmission is suppressed.

[0009]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 3 show a first embodiment of the present invention. In FIG. 1, 2 is an engine,
Reference numeral 4 is a cylinder block, 6 is a cylinder head, and 8 is a crankcase. A crankshaft (not shown) pivotally supported by the cylinder block 4 is provided with a drive side timing sprocket 10 which is a drive side winding body. A cam shaft (not shown) pivotally supported by the cylinder head 6 is provided with a driven side timing sprocket 12 which is a driven side winding body.

A timing chain 14, which is a transmission tool, is wound around the driving side timing sprocket 10 and the driven side timing sprocket 12.

A timing adjusting device 16 is provided in order to adjust the tension of the timing chain 14 to adjust the driving timing between the driving side and the driven side.

As shown in FIG. 1, the timing adjusting device 16 comprises a chain guide 18 which is a transmission guide and a guide operating mechanism 20 which operates the chain guide 18, and is arranged on the tension side of the timing chain 14. It

The chain guide 18 contacts the timing chain 14, and in the first embodiment, as shown in FIG. 3, the first pressing member 22, the second pressing member 24, and the first pressing member 24. It is composed of a central member 26 located at the central portion so as to connect the second pressing member 24 and the second pressing member 24, and has a balance type.

As shown in FIG. 3, the first pressing member 22 includes
Arc-shaped first contacting the inner surface of the timing chain 14
A contact surface 28 is formed. This first pressing member 22
Is to push the timing chain 14 in the tensioning direction. Further, the second pressing member 24 is provided with an arc-shaped second contact surface 30 that is in contact with the outer surface of the timing chain 14. The second pressing member 24 presses the timing chain 14 in a direction to loosen it. Further, the central member 26 is formed with a shaft hole 34 through which the pivot 32 is inserted. This pivot 32 is used for the cylinder block 4
Fixed to. As a result, the chain guide 18 is rotatable about the central member 26.

The guide operating mechanism 20 is composed of a temperature sensitive operating tool 36 and a spring 38, and is disposed inside the timing chain 14. The temperature-sensitive operating tool 36 includes a wax case 40 fixedly mounted on the cylinder block 4, a thermowax 44 which is enclosed in a housing hole 42 of the wax case 40 and expands and contracts depending on an ambient temperature state, and the thermowax 44. Piston 46 that moves back and forth due to expansion and contraction
Consists of The tip side of the piston 46 is locked by a locking tool 48 fixed to the second pressing member 24.

One end of the spring 38 is attached to the cylinder block 4 and the other end of the spring 38 is the first pressing member 22.
It has an urging force that is attached to the rear surface of the first pressing member 22 and presses the first pressing member 22 inside the timing chain 14.

Next, the operation of the first embodiment will be described.

When the engine 2 is at normal temperature (when it is cold), as shown in FIG. 1, since the thermowax 44 of the temperature-sensitive operating tool 36 of the guide operating mechanism 20 is not expanded, the chain path of the timing chain 14 is long. So that
By the biasing force of the spring 38, the first pressing member 22 presses the timing chain 14 from the inside to the outside, and the second pressing member 24 presses the timing chain 14 from the outside to the inside.

When the ambient temperature of the engine 2 rises, as shown in FIG. 2, the chain guide 18 is rotated as shown in FIG. 2, and when the thermowax 44 expands, the piston 46 pushes to move forward. Since the second pressing member 24 is pressed to the outside of the timing chain 14, the chain guide 18 is pushed back to the left around the central member 26, which shortens the chain path, and thus the timing chain 14 is stretched. To the side,
Compensating for the small growth on the timing chain 14 side,
It can be the same as the extension on the cylinder block 4 side.

When the engine 2 is at room temperature, the thermowax 44 shrinks and the piston 46, as shown in FIG.
Has retreated and has lengthened the chain path.

As a result, even if the engine 2 has a different coefficient of thermal expansion and the ambient temperature of the engine 2 rises, the drive timings of the driving side and the driven side can be maintained at the set values.

Further, since the chain guide 18 is provided on the tension side of the timing chain 14, the vibration of the timing chain 14 can be suppressed.

Further, since the impact load acting on the timing chain 14 at the time of starting is buffered by the spring 38 via the chain guide 18, the starting can be smoothly performed.

Furthermore, as shown in FIG. 3, since the chain guide 18 is a balance type, the main parts are housed inside the timing chain 14, and the guide operating mechanism 2
0 can also be housed inside the timing chain 14 and can be made compact.

FIG. 4 shows a second embodiment of the present invention.

In the second embodiment, the parts having the same functions as those in the first embodiment will be described with the same reference numerals.

The features of the second embodiment are as follows. That is, the chain guide 18 includes the pressing member 102. The pressing member 102 has an arcuate contact surface 104 that contacts the outer surface of the timing chain 14.

One end of the pressing member 102 is swingably provided by a pivot 106 fixed to the cylinder block 4.

The other end of the pressing member 102 is supported by the guide operating mechanism 20. In this case, in the second embodiment, the other end of the pressing member 102 is pressed from the inner side of the timing chain 14 to the outer side by the temperature-sensitive operation tool 36, and the spring 38 moves from the outer side to the inner side of the timing chain 14. Pressed.

According to the construction of the second embodiment, at normal temperature, the chain guide 18 is pressed by the spring 38 to press the timing chain 14 from the outside to the inside centering on the pivot 106 and is supported by the piston 46. Therefore, the force of the piston 46 and the force of the spring 38 are balanced.

Then, when the atmospheric temperature rises, the thermowax 44 expands and the pushing member 102 is pushed rightward (clockwise) by the pushing of the piston 46, so that the chain path is shortened, which causes the timing. The chain 14 is fed out, and the timing chain 14 is extended by an amount corresponding to the extension of the cylinder block 4 side due to the temperature rise, and the drive timing is held at the set value. Thereby, the driving side and the driven side can be driven at the same timing. Moreover, the structure of the chain guide 18 can be simplified.

[0032]

As is apparent from the above detailed description, according to the present invention, the transmission guide which is in contact with the transmission is disposed on the tension side of the transmission, and the length of the transmission is substantially increased according to the ambient temperature condition. By providing a guide operation mechanism that operates the transmission guide to adjust the height, even if a material with a large coefficient of thermal expansion is used for the cylinder block, the driven side winding body is driven at the same timing as the initial setting. Also, the impact load acting on the transmission at the time of starting is buffered by the guide actuating mechanism, and further, since the transmission guide is provided on the tension side of the transmission, vibration of the transmission can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a timing adjusting device provided in an engine at room temperature.

FIG. 2 is a configuration diagram of a timing adjusting device provided in the engine at a high temperature.

FIG. 3 is an enlarged configuration diagram of a timing adjustment device.

FIG. 4 is an enlarged configuration diagram of a timing adjusting device according to a second embodiment.

FIG. 5 is a configuration diagram of a conventional timing adjustment device.

[Explanation of symbols]

 2 engine 4 cylinder block 6 cylinder head 10 driving side timing sprocket 12 driven side timing sprocket 14 timing chain 18 chain guide 20 guide operating mechanism 36 temperature-sensitive operating tool 38 spring

Claims (3)

[Claims] 1. A timing adjusting device for adjusting drive timing between a driving side and a driven side by adjusting tension of a transmitting tool wound around a driving side winding body and a driven side winding body. And a guide actuating mechanism for activating the transmission guide so as to adjust the substantial length of the transmission according to the ambient temperature condition. A timing adjustment device characterized by. 2. The transmission guide is configured by connecting a first pressing member that presses an inner surface of the transmission and a second pressing member that presses an outer surface of the transmission by a central member. The timing adjusting device according to claim 1, wherein the timing adjusting device is a transmission guide that is rotatably provided around a central member. 3. The transmission tool guide according to claim 1, wherein one end of the transmission guide is pivotally supported so as to be swingable, and the other end of the transmission guide is a pressing member supported by the guide operating mechanism. Timing adjustment device.