JPH08233041A - Autotensioner - Google Patents

Abstract

PURPOSE: To enable a guide member for guiding a power transmission means to rock, with a fulcrum member as a fulcrum, so as to simplify the structure, by making a sealing member emerge or sink from or under a pressure chamber being supplied with oil pressure from an oil pressure supply passage thereby varying the volume. CONSTITUTION: Since a pressure chamber 31 is always communicating with outside (atmosphere) through an orifice 37 and an oil discharge port 36, oil pressure is supplied from a ball valve 33 so that the pressure may be specified pressure while the oil pressure within the pressure chamber 31 leaks to outside. Especially, the oil pressure leaking from an oil discharge port 36 flows out to the sliding face 26 of the guide member 21, so the sliding of a chain becomes smooth. Moreover, when oil pressure is supplied from the oil pressure supply port 23 of the fulcrum member 22 to the oil pressure supply passage 25 of the guide member 21 through a passage, the oil pressure is supplied onto the periphery of the fulcrum member 22 since the passage and the oil pressure supply port 25 are communicating with each other on the periphery of the fulcrum member 22, and when the guide member 21 rocks, it performs lubrication effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto tensioner.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, an automatic tensioner disclosed in Japanese Utility Model Laid-Open No. 64-25557 discloses
It is stretched between the two pulleys 101 and 102, and serves to properly maintain the tension of the chain 103 that transmits power.

The automatic tensioner 110 is fixed to a member such as an engine block (not shown), and the urging force of the hydraulic pressure and the spring pressure in the pressure chamber 111 formed inside the chain is transmitted from the plunger 112 via the chain guide 113 to the chain. It is given to 103. Then, as is well known, by moving the plunger 112 in the horizontal direction in the drawing,
The tension of the chain 103 is adjusted.

By the way, the automatic tensioner 1 shown in FIG.
Although 10 is a very commonly used one, the tensioner 110 and the chain guide 113 are independent of each other, resulting in a high manufacturing cost and a large number of assembly steps.

[0005]

Therefore, an object of the present invention is to simplify the automatic tensioner.

[0006]

The first means taken in the present invention for solving the above-mentioned problems is power transmission means, a guide member for guiding the power transmission means, and swinging of the guide member. A fulcrum member that is freely supported, a pressure chamber formed inside the guide member, a sealing member that can be retracted and retracted in the pressure chamber, and a volume of the pressure chamber is variable, and a hydraulic pressure is applied to the pressure chamber. That is, the automatic tensioner is composed of a hydraulic pressure supply passage for supplying the.

In addition to the first means, the second means taken in the present invention to solve the above-mentioned problems is that the oil drain hole of the pressure chamber is opened on the sliding surface of the guide member. Is.

In addition to the first means, a third means taken in the present invention to solve the above-mentioned problems is a hydraulic supply hole having a hydraulic supply passage formed in the fulcrum member, and the fulcrum member. That is, they are communicated on the outer circumference of.

[0009]

According to the above-mentioned first means, the volume of the pressure chamber to which the hydraulic pressure is supplied from the hydraulic pressure supply passage is made variable by the protruding and retracting of the sealing member with respect to the pressure chamber. The guide member that guides swings about the fulcrum member.

According to the above-mentioned second means, the oil flowing out from the oil drain hole is supplied to the sliding surface of the guide member.

According to the above-mentioned third means, oil is supplied from the hydraulic pressure supply hole formed in the fulcrum member to the hydraulic pressure supply passage on the outer circumference of the fulcrum member.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a power transmission means composed of a chain 14 is arranged between a crank pulley 11 and timing pulleys 12 and 13 of an engine (not shown). The chain 14 needs to be stretched with an appropriate tension, and since the chain 14 expands and contracts depending on the ambient temperature, the auto tensioner 20 is required.

The automatic tensioner 20 will be described with reference to FIG.

The chain guide (guide member) 21 is swingable around a pin (fulcrum member) 22 as a fulcrum. A hydraulic pressure supply hole 23 is formed at substantially the center of the pin 22 and communicates with a hydraulic pressure source (hydraulic pump) not shown. A passage 24 that opens from the hydraulic pressure supply hole 23 toward the outer periphery of the pin 22
The hydraulic pressure supply hole 23 communicates with the hydraulic pressure supply passage 25 formed in the chain guide through the outer periphery of the pin 22. The right side surface of the chain guide 21 is formed in an arc shape and serves as a sliding surface 26 of the chain 14.

The pin 22 is located at the lower end of the chain guide 21, and the hydraulic pressure supply path 25 extends upward from this lower end and communicates with the pressure chamber 31 located at the upper end of the chain guide 21. In the pressure chamber 31, a ball valve 32 is provided in a communication portion with the hydraulic pressure supply passage, and allows the hydraulic pressure to flow only from the hydraulic pressure supply passage 25 to the pressure chamber 31. The left end of the pressure chamber 31 is liquid-tightly sealed by a rod (sealing member) 33, and a spring 34 is stretched between the pressure chamber 31 and the right end thereof. Rod 33 is pressure chamber 3
The pressure chamber 31 is variable in volume within the pressure chamber 31. The left end of the rod 33 is formed in a spherical shape and is in contact with a stationary member 35 such as a chain case. The pressure chamber 31 further has an oil drain hole 36, and the oil drain hole 36 is opened on the sliding surface 26 of the guide member 21. An orifice 37 is inserted in the middle of the oil drain hole 36.

The automatic tensioner 20 having the above structure
The action of will be described below.

With the start of the engine, the chain 14 transfers the rotational torque of the crank pulley 11 to the timing pulley 1.
Transfer to 2 and 13. At the same time, the hydraulic pressure source generates hydraulic pressure and supplies the hydraulic pressure to the pressure chamber 31 via the hydraulic pressure supply hole 23, the passage 24, the hydraulic pressure supply passage 25 and the ball valve 32. The chain 14 expands and contracts according to the temperature atmosphere and the operating condition of the engine, but it is necessary to be stretched with a predetermined tension in order to perform a normal power transmission function. The tension of the chain 14 is formed by the sum of the hydraulic pressure in the pressure chamber 31 and the urging pressure of the spring 34. Here, since the pressure chamber 31 is in constant communication with the outside (atmosphere) through the orifice 37 and the oil drain hole 36, the hydraulic pressure inside the pressure chamber 31 leaks to the outside, but the pressure becomes a predetermined pressure. Thus, the hydraulic pressure is supplied from the ball valve 32. In particular, the hydraulic pressure leaking from the oil drain hole 36 flows out to the sliding surface 26 of the guide member 21, so that the chain 14 slides smoothly. Further, when hydraulic pressure is supplied from the hydraulic pressure supply hole 23 of the fulcrum member 22 to the hydraulic pressure supply passage 25 of the guide member 21 via the passage 24, the passage 24 and the hydraulic pressure supply passage 25 communicate with each other on the outer circumference of the fulcrum member. Therefore, hydraulic pressure is supplied to the outer circumference of the fulcrum member 22, and a lubricating effect is achieved when the guide member 21 swings.

Now, from the state shown in FIGS.
If 4 is extended, the tension of the chain 14 will be reduced as it is. However, at the same time, the urging pressure of the spring 34 moves the guide member 21 to the right with respect to the rod 33 that maintains the same position. (Rotate to the right using the fulcrum member 22 as a fulcrum) As a result, the volume in the pressure chamber 31 increases, and the hydraulic pressure in the pressure chamber 31 decreases. Then, the ball valve 32 is opened to supply the hydraulic pressure into the pressure chamber 31, and the hydraulic pressure inside the pressure chamber 31 becomes a predetermined pressure, that is, the tension of the chain 14 also becomes a predetermined pressure.

On the contrary, from the state shown in FIGS.
If 4 is contracted, the tension of the chain 14 will increase as it is. However, at the same time, this tension pushes the guide member 21 leftward (swings leftward about the fulcrum member 22 as a fulcrum), so that the volume in the pressure chamber 31 is reduced,
The hydraulic pressure in the pressure chamber 31 rises. Then, the hydraulic pressure in the pressure chamber 31 is discharged to the outside through the orifice 37 and the oil discharge hole 36, and the hydraulic pressure in the pressure chamber 31 becomes a predetermined pressure, that is, the tension of the chain 14 also becomes a predetermined pressure.

[0021]

According to the first aspect of the present invention, the pressure chamber supplied with the hydraulic pressure from the hydraulic pressure supply passage has a variable volume due to the sealing member projecting and retracting with respect to the pressure chamber. Since the guide member that guides the transmission means swings around the fulcrum member as a fulcrum, it is possible to apply an appropriate tension to the power transmission means by the hydraulic pressure of the pressure chamber.

According to the second aspect of the invention, since the oil drain hole is opened on the sliding surface of the guide member, the lubricating oil can be supplied to the power transmission means sliding on the sliding surface, and the power transmission can be achieved. The sliding of the means can be made smooth and the life of the power transmission means can be extended.

According to the third aspect of the present invention, the guide member is supported by the fulcrum member, and the hydraulic pressure supply passage formed in the guide member is on the outer circumference of the hydraulic pressure supply hole formed in the fulcrum member and the fulcrum member. Since they are communicated with each other, the lubricating oil can be supplied to the supporting portion between the guide member and the fulcrum member, and the rocking of the guide member relative to the fulcrum member becomes smooth.

[Brief description of drawings]

FIG. 1 is a system of an auto tensioner according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of part A in FIG.

3 is a side view of the auto tensioner of FIG. 1. FIG.

FIG. 4 is a conventional auto tensioner.

[Explanation of symbols]

21 ... Guide member, 22 ... Support member, 25 ...
-Hydraulic supply path, 31 ... Pressure chamber, 33 ... Sealing member.

Claims (3)

[Claims] 1. A guide member for guiding a power transmission means, a fulcrum member for rotatably supporting the guide member, a pressure chamber formed inside the guide member, and a pressure chamber capable of projecting and retracting in the pressure chamber. The auto tensioner includes a sealing member that makes the volume of the pressure chamber variable, and a hydraulic pressure supply path that supplies hydraulic pressure to the pressure chamber. 2. The automatic tensioner according to claim 1, wherein an oil drain hole of the pressure chamber is opened on a sliding surface of the guide member. 3. The auto tensioner according to claim 1, wherein the hydraulic pressure supply passage communicates with a hydraulic pressure supply hole formed in the fulcrum member on an outer circumference of the fulcrum member.