JPH10141451A - Tensile force adjusting device for chain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a necessity of the formation of an oil passage in a tensile force adjusting device for a chain which uses a hydraulic chain tensioner. SOLUTION: A slipper 4 and a chain tensioner 10 which presses a chain on a loose side 3a through the slipper 4 are provided on the chain on the loose side 3a which runs by facing sideways. A chain tensioner 10 of oil sealing type is adopted as the chain tensioner 10, the chain tensioner 10 is supported in such a manner that a cylinder chamber 13 faces upward and downward and the chain tensioner can oscillate freely, a contact part 41 of a rod 20 of the chain tensioner 10 is provided on the chain tensioner 10, and the slipper 4 is pressed by a lower end of a body 11 to give tensile force to the chain on the loose side 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain tension adjusting device for maintaining a constant chain tension of a chain such as a camshaft driving chain.

[0002]

2. Description of the Related Art Generally, in a chain for driving a camshaft, an adjusting force of a chain tensioner is applied to maintain a predetermined tension. Although there is a mechanical type of the above chain tensioner, since a change in chain tension cannot be smoothly absorbed, a hydraulic chain tensioner has been widely used in place of such a mechanical chain tensioner. It has become to.

[0003]

The hydraulic chain tensioner conventionally known is of an oil supply type for supplying oil, so that an oil passage communicating with the oil supply port of the chain tensioner is formed in the engine block. There is a need to. In addition, since oil must be supplied to the chain tensioner from the oil passage, an oil pump is required.When using an oil pump that supplies oil to other sliding parts, a large pump with a large discharge rate is required. There is a disadvantage that it must be used.

An object of the present invention is to provide a tension adjusting device for a chain using a hydraulic chain tensioner, which eliminates the need for machining an oil passage and the use of an oil pump.

[0005]

In order to solve the above-mentioned problems, the present invention provides a tension adjusting device for a chain, comprising: a slipper for guiding a chain on a slack side chain of the chain; A chain tensioner for applying a tension adjusting force to the chain through the lower end of the chain tensioner is inserted into the body,
An oil-sealed chain tensioner that has a rod that is provided with an outward projecting property by a rod spring and buffers the oil enclosed in the body provided to the rod, and swings the body of the chain tensioner. It is movably supported, and a configuration is adopted in which a contact portion of a rod is provided at a fixed portion on the chain tensioner so that the slipper is pressed at the lower end of the body.

Here, in order to reduce the weight of the chain tensioner, the body body forming the body is formed of aluminum.

If the chain tensioner and the slipper are separately assembled, it takes time and effort to assemble, and the slipper is integrally provided at the lower end of the body in order to facilitate the assembly.

Further, if the viscosity of the oil enclosed in the chain tensioner changes due to a temperature change, the response of the chain tensioner to fluctuations in the tension of the chain deteriorates, and the response is improved. An oil based on polyalphaolein having a constant viscosity over a wide range is used.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a chain transmission device for driving a camshaft. In a chain 3 for transmitting rotation of a crankshaft 1 to a camshaft 2, a slack side chain 3a running in a lateral direction is positioned above a tension side chain 3b. It is a layout.

A slipper 4 for guiding the movement of the chain 3 is provided above the slack side chain 3a, and a chain tensioner 10 is disposed on the slipper 4.

FIGS. 2 and 3 show the slipper 4 and the chain tensioner 10 in detail. One end of the slipper 4 is supported by a pin 5 to be swingable, and a guide groove 6 for guiding the movement of the chain 3 is formed on the lower surface.

The chain tensioner 10 has a body 11, and the body 11 forms a cylinder chamber 13 having an upper part opening in a body main body 12 made of aluminum, and a steel sleeve 14 is inserted into the cylinder chamber 13. doing.

The body body 12 has a mounting piece 15 at an upper portion on one side. A projection 16 is provided on the lower surface of the body 12, and a spherical surface 17 formed on the lower surface of the projection 16 is in contact with the slipper 4.

The upper opening of the cylinder chamber 13 is hermetically sealed by mounting an oil seal 18.
An air layer is formed between the cylinder and the oil filled in the cylinder chamber 13.

The oil seal 18 has a rod insertion hole 19
And a rod 20 inserted into the rod insertion hole 19
Has a step 21 in the middle of the outer periphery, and a wear ring 23 slidably inserted into a small-diameter shaft portion 22 below the step 21 is pressed by a rod spring 24 and pressed against the step 21, and The rod 20 is provided with an outwardly projecting property by the elastic force. Reference numeral 25 denotes an oil passage hole formed in the wear ring 23. The wear ring 23 may be fixed to the rod 20 by press fitting.

At the lower end of the rod 20, the rod 20
Is provided with a damper 30 for buffering the pushing force applied to the pressure sensor.

The buffer damper 30 has a plunger 31 slidable along the inner diameter surface of the sleeve 14 at the lower end of the rod 20. The plunger 31 communicates a lower pressure chamber 32 and an upper reservoir chamber 33. A passage 34 is formed, and a check valve 35 is provided at a lower end of the passage 34. The check valve 35 closes the passage 34 when the pressure in the pressure chamber 32 becomes higher than the pressure in the reservoir chamber 33. 3
Reference numeral 6 denotes a plunger spring that pushes up the plunger 31.

The chain tensioner 10 is a gas-liquid two-phase oil-sealed type in which an oil and air layer is provided in a cylinder chamber 13. In the chain tensioner, a rod spring 24 is stored outside a sleeve 14. When the space 26 is formed, the axial length of the body 11 can be reduced in size by an amount corresponding to the height of the storage space 26.

The chain tensioner 10 includes a mounting piece 15
Is supported by a pin 40 so as to be swingable, and a stopper pin 41 as a contact portion with which the rod 20 abuts is fixed to an upper portion of the chain tensioner.

When the tension of the slack side chain 3a changes due to the fluctuation of the rotation torque and the slack side chain 3a is slackened, the rod 20 is pressed against the stopper pin 41 by the pressing of the rod spring 24. The body 11 swings downward about the pin 40.

At this time, since the pressure in the pressure chamber 32 becomes lower than the pressure in the reservoir chamber 33, the check valve 35 opens the passage 34 and the oil in the reservoir chamber 33
4 smoothly flows into the pressure chamber 32. For this reason, the body 11 swings rapidly downward, and absorbs the slack of the slack side chain 3 a via the slipper 4.

Conversely, when the tension of the slack side chain 3a increases, the slack side chain 3a presses the body 11 upward through the slipper 4. At this time, since the pressure in the pressure chamber 32 becomes higher than the pressure in the reservoir chamber 33, the check valve 35 closes the passage.

Therefore, the pressing force for pushing up the body 11 is buffered by the oil sealed in the pressure chamber 32, and the slack side chain 3a is held in a tension state. When the above pressing force is stronger than the elasticity of the rod spring 24, the pressure chamber 3
The oil of No. 2 leaks from the leak gap formed between the sliding surface of the plunger 31 and the sleeve 14 into the reservoir chamber 33, and the body 11 slowly moves upward to a position where the above pressing force and the elasticity of the rod spring 24 are balanced. do it,
The tension of the slack side chain 3a is kept constant.

Here, the oil sealed in the cylinder chamber 13 of the chain tensioner 10 may be any of mineral oil, silicone oil, and oil containing polyalphaolefin as a main component. When an oil containing polyalphaolefin as a main component is used as the oil, the viscosity of the oil is substantially constant over a wide temperature range from a low temperature to a high temperature. Even if it occurs, the oil in the reservoir chamber 33 flows smoothly from the passage 34 into the pressure chamber 32, and the slack of the chain during the low temperature start can be smoothly absorbed.

Further, since polyalphaolefin has excellent lubricity, it is possible to improve the slidability of the plunger 31 and prevent the sliding surface from being worn.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the slipper 4 is integrally provided at the lower end of the body 11.

By integrating the body 11 and the slipper 4 as described above, the assembly is easier than in the case where the chain tensioner 10 and the slipper 4 are separately assembled.

In the embodiment, the chain tensioner 10
The oil-sealed type of gas-liquid two-phase structure in which the change in the volume of oil in the reservoir chamber 33 due to the movement of the plunger 31 is absorbed by the air layer between the oil seal 18 and the oil has been described. Not done. For example,
An oil-sealed chain tensioner that absorbs a change in volume of oil filling the reservoir chamber by deformation of the bellows may be used.

[0029]

As described above, in the present invention, since the tension of the chain is kept constant by using the oil-sealed chain tensioner of the gas-liquid two-phase structure, it is not necessary to supply oil. For this reason, the processing of the oil passage and the use of the oil pump can be eliminated.

Further, since the body is formed of aluminum, the weight can be reduced.

Since the slipper is provided integrally with the lower end of the body, the assembling can be facilitated.

By using an oil containing polyalphaolefin as a main component, even if the chain suddenly slackens at a low temperature start, the slack can be smoothly absorbed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a partially cutaway front view showing the same chain tensioner.

FIG. 3 is a longitudinal side view of the above.

FIG. 4 is a partially cutaway front view showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 chain 3a slack side chain 4 slipper 10 chain tensioner 11 body 12 body body 20 rod

Claims (4)

[Claims] 1. A tension adjusting device for a chain, comprising: a slipper for guiding a chain on a slack side chain of the chain; and a chain tensioner for applying a tension adjusting force to the chain via the slipper. The tensioner has a rod having a lower end inserted into the body and having an outward protruding property provided by a rod spring, and a pushing force applied to the rod is buffered by oil sealed in the body. A chain of an oil-sealed chain tensioner, which swingably supports the body of the chain tensioner, and has a fixed portion on the chain tensioner provided with a rod abutting portion to press the slipper at the lower end of the body. Tension adjustment device. 2. The tension adjusting device for a chain according to claim 1, wherein the body includes a body main body made of aluminum. 3. The chain tension adjusting device according to claim 1, wherein the slipper is provided integrally with a lower portion of the body. 4. The chain tension adjusting device according to claim 1, wherein the oil contains polyalphaolefin as a main component.