JP2006070992A - Hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and light tensioner capable of locking a compression stroke without using a solenoid valve. <P>SOLUTION: In this hydraulic tensioner 10, a plunger 12 is provided with a first communication passage 30 for communicating a high-pressure chamber 16 with a low-pressure chamber 24, and a cylinder 11 is provided with a second communication passage 51 for communicating the high-pressure chamber 16 with the low-pressure chamber 24, and the second communication passage 51 is provided with a check valve 52 for hindering flow of operating fluid from the high-pressure chamber 16 to the low-pressure chamber 24. The first communication passage 30 is provided with an orifice 45, and a pressure depending valve 40 is provided to close the first communication passage 30 with constant pressure of the high-pressure chamber 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic tensioner such as an auto tensioner that applies tension to a belt or chain stretched between a driving wheel and a driven wheel.

  Since the auto tensioner applies tension to the belt or chain (hereinafter referred to as a belt), when the tension of the belt increases and the plunger is about to be compressed, a damping force is generated for the compression, and the tension of the belt is reduced to reduce the plunger. When trying to stretch, speed up the stretching.

  In addition, there is a hybrid vehicle in which two drive sources including an engine and an electric motor are wound around one belt, and the drive sources are switched as appropriate. In such a hybrid vehicle, there is one in which an auto tensioner for adjusting the belt tension is disposed at a position downstream of the engine and upstream of the electric motor. However, when the engine is started by the electric motor with the engine stopped, the auto tensioner compresses and the belt slips. Therefore, it is necessary to lock the compression stroke of the auto tensioner in order to keep the belt from slipping.

As a conventional auto-tensioner, as described in Patent Document 1, a plunger is slidably inserted into a cylinder, the cylinder is attached to the fixed member side located above, and the plunger is located on the pulley side located below. A high-pressure oil chamber (high-pressure chamber) defined by the cylinder and the pressurizing portion of the plunger is formed in the cylinder, and an oil reservoir chamber having an upper portion as a gas chamber on the outer periphery of the plunger and the cylinder An outer cylinder that divides the (low pressure chamber) is provided, a first communication passage that communicates the gas chamber and the high pressure oil chamber is provided at an upper portion of the cylinder, and the high pressure oil chamber and the oil reservoir chamber communicate with the plunger. A second check passage that closes when compressed, and a second check passage that closes when compressed. It is followed by a provided. And in this auto tensioner, in order to lock the compression stroke at the time of engine starting, it is supposed that the 1st check valve provided in the 1st communicating path is closed by an electromagnetic valve.
JP2004-150602

The conventional tensioner has the following problems.
(1) Solenoid valves are expensive, large and heavy, and are not easily mounted on actual machines.
(2) A control device is required to turn on the solenoid valve when starting the engine.

  An object of the present invention is to provide a hydraulic tensioner that is compact and lightweight and can lock a compression stroke without using a solenoid valve.

  In the first aspect of the invention, a cylinder is disposed in the outer cylinder, a low pressure chamber is defined between the cylinder and the outer cylinder, a plunger is slidably inserted in the axial direction, and the plunger is extended in the extending direction. A spring for biasing is interposed, a high pressure chamber defined by the tip of the cylinder and the plunger is provided in the cylinder, a first communication passage is provided in the plunger for communicating the high pressure chamber and the low pressure chamber, A hydraulic tensioner provided with a second communication passage communicating the high-pressure chamber and the low-pressure chamber, and provided with a check valve for blocking the flow of working fluid from the high-pressure chamber to the low-pressure chamber in the second communication passage. An orifice is provided, and a pressure-dependent valve that closes the first communication path by a constant pressure in the high-pressure chamber is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the pressure-dependent valve is a spool valve that moves in response to the pressure in the high-pressure chamber.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the pressure-dependent valve is built in a plunger.

(Claim 1)
(a) In a normal use state of the hydraulic tensioner, when the plunger is compressed, the check valve of the second communication passage is closed, and the fluid in the high pressure chamber passes through the orifice of the first communication passage to generate a damping force. When the plunger is extended, the check valve of the second communication passage is opened, and the fluid in the low-pressure chamber immediately flows into the high-pressure chamber, so that the extension is accelerated.

  (b) When the plunger of the hydraulic tensioner is rapidly compressed, the pressure in the high pressure chamber exceeds a certain value due to the presence of the orifice, and the pressure dependent valve closes the first communication path. At this time, since the check valve of the second communication path is also closed, the compression stroke of the tensioner is locked.

  (c) Since the hydraulic tensioner can lock the compression stroke as described above (b) without using a solenoid valve, it can be reduced in cost, reduced in size and weight, and does not require an electric control device.

(Claim 2)
(d) Since the pressure-dependent valve is a spool valve, when the pressure in the high pressure chamber increases, the spool is pushed back due to the pressure difference between the front and rear of the spool, and the valve closes the first communication path.

(Claim 3)
(e) Since the pressure-dependent valve is built in the plunger, the size can be reduced.

  1 is an overall cross-sectional view showing a hydraulic tensioner, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a cross-sectional view showing a pressure-dependent valve.

  For example, in a hybrid vehicle, the hydraulic auto tensioner 10 is provided between a fixed member such as an engine block and an idle pulley, and presses the idle pulley against a belt stretched between a drive wheel and a driven wheel. Apply tension to the belt.

  As shown in FIGS. 1 to 3, the auto tensioner 10 includes a pressurizing portion 13 provided with a piston ring 13 </ b> A (seal member) of a plunger 12 slidably inserted in an axial direction inside a cylinder 11, and vertically The cylinder 11 on the lower side is attached to the fixed member side, and the idle pulley is attached to the plunger 12 side on the upper side. The plunger 12 includes an attachment member 14 at the top. The cylinder 11 includes an attachment member 15 at the lower part.

  The auto tensioner 10 forms in the cylinder 11 a high pressure oil chamber 16 (high pressure chamber) partitioned by the cylinder 11 and the pressurizing portion 13 of the plunger 12. The plunger 12 comprises the pressurizing part 13 with the plunger 12 itself, and the distal end part (lower end part) of the plunger 12 is slightly larger in diameter than the base end part (upper end part). The pressurizing unit 13 is in sliding contact with the inner periphery of the cylinder 11. The plunger 12 locks the stepped end surface near the base end portion (small diameter portion) of the pressurizing portion 13 in the axial direction to a retaining ring 17 engaged with the inner periphery of the upper end opening of the cylinder 11 to restrict the extended end. When the plunger 12 is compressed, an annular gap is formed between the outer periphery of the base end part following the pressurizing part 13 of the plunger 12 and the inner circumference of the cylinder 11. This annular gap is a part of an oil reservoir chamber 24 described later. It becomes what constitutes.

  The plunger 12 may have a large diameter portion that slides in contact with the inner periphery of the cylinder 11 at the maximum compression, and the retaining ring 17 provided on the inner periphery of the upper end opening of the cylinder 11 may be removed.

  The auto tensioner 10 is provided with a casing 21 that is integrally formed with a mounting member 15 that is fixed to the lower portion of the cylinder 11 by caulking or the like. The casing 21 has an upper end opened, and a flexible boot 23 is provided between the opening 21 </ b> A of the casing 21 and the upper mounting member 14 on the plunger 12 side. The boot 23 includes a thin portion 23C that can extend and contract in the axial direction at an intermediate portion between the lower thick portion 23A and the upper thick portion 23B, and the lower locking convex portion 23D is formed into an annular concave portion on the outer periphery of the casing 21. The upper locking projection 23E is liquid-tightly engaged with the annular groove of the upper mounting member 14 in a liquid-tight manner. The casing 21 and the boot 23 form the outer cylinder 20. In the auto tensioner 10, the space that the outer cylinder 20 seals between the cylinder 11 and the outer periphery of the plunger 12 is an oil reservoir chamber 24 (oil level L) (low pressure chamber), and the upper portion of the oil reservoir chamber 24 is gas. Let it be chamber 24A. Oil as a working fluid is loaded into the high-pressure oil chamber 16 and the oil reservoir chamber 24. The thin portion 23C of the boot 23 absorbs the expansion and contraction of the plunger 12.

  The boot 23 has an intermediate portion in the axial direction as a thin portion 23C, and the inner diameter of the thin portion 23C is narrower than the inner diameters of the upper and lower thick portions 23A and 23B so as to be slidable into the outer peripheral downward skirt portion 14A of the upper mounting member 14. Adhere. The lower thick portion 23A of the boot 23 mainly defines the gas chamber 24A, and the upper thick portion 23B of the boot 23 defines the exhaust chamber 24B and extends in the axial direction of the inner periphery of the thin portion 23C of the boot 23. A spline groove-shaped ventilation groove 23F communicates the gas chamber 24A with the exhaust chamber 24B. The upper thick portion 23B of the boot 23 includes an exhaust check valve 25 for exhausting high-temperature expanded air from the gas chamber 24A and the exhaust chamber 24B to the outside. The exhaust check valve 25 prevents the inflow of air from the outside to the exhaust chamber 24B.

  The outer cylinder 20 is composed of only a single boot that has upper and lower ends engaged with the cylinder 11 side and the plunger 12 side, respectively, and expands and contracts in the axial direction. Not required.

  The auto tensioner 10 is provided with a first communication passage 30 that connects the high-pressure oil chamber 16 and the oil reservoir chamber 24 (gas chamber 24 </ b> A) to the plunger 12. The first communication passage 30 is open to the oil reservoir chamber 24 in a crossing communication with the large-diameter to small-diameter vertical holes 31 that open to the high-pressure oil chamber 16 and the upper-side small-diameter holes of the vertical holes 31. It consists of a horizontal hole 32. A pressure-dependent valve 40 is built in the vertical hole 31 of the plunger 12.

  The pressure-dependent valve 40 is composed of a spool valve 40A, and an annular spring receiver 41 and a valve seat 42 are inserted into the medium diameter hole of the vertical hole 31, and these springs are inserted into the large diameter hole of the vertical hole 31 by these valve cases 43. The receiver 41 and the valve seat 42 are held. A spool 44 is accommodated in the valve seat 42 with play, and a stem 44A fixed on the central axis of the spool 44 is passed through a central hole of the valve seat 42 through an orifice 45 formed of an annular gap. The spring 46 accommodated in the valve seat 42 while being backed up by the spring receiver 41 urges the stem 44 </ b> A to the side of the valve seat 42 that protrudes from the seat surface 42 </ b> A.

  The protruding end of the stem 44A enables the ball valve 47 held in the central recess 43A of the valve case 43 to be pushed. The valve case 43 holds the ball valve 47 in a freely movable manner in the central recess 43 </ b> A, and opens a communication hole 43 </ b> B provided in communication with both sides in the radial direction of the central recess 43 </ b> A into the high-pressure oil chamber 16. The spool 44 and the ball valve 47 constitute a spool valve 40A of the present invention, which abut against each other by the pressure of the high pressure oil chamber 16, and contact the seat surface 42A of the valve seat 42 in response to the pressure of the high pressure oil chamber 16. Move away. The spool 44 and the ball valve 47 may be integrally joined.

  In the pressure-dependent valve 40, when the pressure in the high pressure oil chamber 16 is smaller than a certain pressure, the urging force of the spring 46 projects the stem 44A of the spool 44 from the seat surface 42A, and the ball valve 47 moves to the seat surface 42A. The high pressure oil chamber 16 communicates with the oil reservoir chamber 24 through the orifice 45 while opening the first communication passage 30. When the pressure in the high-pressure oil chamber 16 reaches a certain pressure, the ball valve 47 is pressed against the seat surface 42A by this pressure to close the first communication passage 30, and the high-pressure oil chamber 16 is not in communication with the oil reservoir chamber 24. Become.

  The auto tensioner 10 is provided with a second communication passage 51 that connects the high-pressure oil chamber 16 and the oil reservoir chamber 24 to the cylinder 11, and the second communication passage 51 closes when the plunger 12 is compressed and opens when the plunger 12 is extended. A check valve 52 is provided. The second communication passage 51 includes a hole 51 </ b> A provided in the valve seat 53 press-fitted into the lower end portion of the cylinder 11, and a groove 51 </ b> B provided in the casing 21 fixed to the lower portion of the cylinder 11. The second check valve 52 is a ball valve, is provided on the seat surface of the valve seat 53, and is prevented from falling outward by a cage-like valve stopper 54 provided around the seat surface of the valve seat 53. The valve 55 is pressed against the seat surface of the valve seat 53 by a spring 55 backed up by the valve stopper 54, and opens and closes to and from the seat surface.

  The auto tensioner 10 includes a spring seat 61 formed on the casing 21 in an oil reservoir chamber 24 formed between the outer cylinder 20 and the cylinder 11 and the plunger 12, and a spring seat 62 supported by the upper mounting member 14 as a backup. And a coil spring 63 for biasing the cylinder 11 and the plunger 12 in the extending direction.

The auto tensioner 10 operates as follows.
(1) The auto tensioner 10 presses the idle pulley against the belt by the urging force of the coil spring 63 and applies a predetermined tension to the belt.

  (2) When the tension of the belt is reduced and the plunger 12 is to be extended by the coil spring 63, the high pressure oil chamber 16 becomes negative pressure, and the check valve 52 of the second communication passage 51 is immediately opened. Is quickly supplied to the high-pressure oil chamber 16, and the plunger 12 is quickly extended.

  (3) When the tension of the belt increases and the plunger 12 is compressed by the belt, the check valve 52 of the second communication passage 51 is closed, and the pressure of the high-pressure oil chamber 16 is increased. However, when the pressure in the high-pressure oil chamber 16 increases to such a level, the pressure-dependent valve 40 does not close, and the oil in the high-pressure oil chamber 16 flows through the orifice 45 to the oil reservoir chamber 24 to generate a pressure-side damping force.

  (4) When the belt tension suddenly increases and the plunger 12 is rapidly compressed by the belt, the pressure in the high pressure oil chamber 16 exceeds a certain value due to the presence of the orifice 45, and the pressure dependent valve 40 is connected to the first communication path. Close 30. As a result, both the pressure-dependent valve 40 of the first communication passage 30 and the check valve 52 of the second communication passage 51 are closed, and the oil in the high-pressure oil chamber 16 is confined to lock the compression stroke of the plunger 12.

According to the present embodiment, the following operational effects can be obtained.
(a) In a normal use state of the auto tensioner 10, when the plunger 12 is compressed, the check valve of the second communication passage 51 is closed, and the fluid in the high pressure oil chamber 16 passes through the orifice 45 of the first communication passage 30 and is attenuated. Generate power. When the plunger 12 is extended, the check valve 52 of the second communication passage 51 is opened, and the fluid in the oil reservoir chamber 24 immediately flows into the high-pressure oil chamber 16 to accelerate the extension.

  (b) When the plunger 12 of the auto tensioner 10 is rapidly compressed, the pressure in the high pressure oil chamber 16 exceeds a certain value due to the presence of the orifice 45, and the pressure dependent valve 40 closes the first communication passage 30. At this time, since the check valve 52 of the second communication passage 51 is also closed, the compression stroke of the auto tensioner 10 is locked.

  (c) Since the auto tensioner 10 can lock the compression stroke as described above (b) without using a solenoid valve, it can be reduced in cost, size and weight, and does not require an electric control device.

  (d) Since the pressure dependent valve 40 is composed of the spool valve 40A, when the pressure in the high pressure oil chamber 16 increases, the spool 44 is pushed back by the pressure difference between the front and rear of the spool 44, and the ball valve 47 is Close the passage 30.

  (e) Since the pressure dependent valve 40 is built in the plunger 12, the size can be reduced.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

FIG. 1 is an overall sectional view showing a hydraulic tensioner. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a sectional view showing the pressure dependent valve.

Explanation of symbols

10 Hydraulic Tensioner 11 Cylinder 12 Plunger 16 High Pressure Oil Chamber (High Pressure Chamber)
20 Outer cylinder 24 Oil reservoir (low pressure chamber)
30 First communication passage 40 Pressure dependent valve 40A Spool valve 45 Orifice 51 Second communication passage 52 Check valve

Claims (3)

Place the cylinder in the outer cylinder,
A low pressure chamber is defined between the cylinder and the outer cylinder,
Insert the plunger into the cylinder slidably in the axial direction,
With a spring that biases the plunger in the direction of extension,
In the cylinder, a high-pressure chamber partitioned by the tip of the cylinder and plunger is provided,
The plunger is provided with a first communication passage communicating the high pressure chamber and the low pressure chamber,
In the hydraulic tensioner, the cylinder is provided with a second communication passage that communicates the high pressure chamber and the low pressure chamber, and the second communication passage is provided with a check valve that prevents the flow of working fluid from the high pressure chamber to the low pressure chamber.
A hydraulic tensioner, wherein an orifice is provided in the first communication path, and a pressure-dependent valve that closes the first communication path by a constant pressure in the high-pressure chamber is provided.   The hydraulic tensioner according to claim 1, wherein the pressure-dependent valve is a spool valve that moves in response to a pressure in the high-pressure chamber.   The hydraulic tensioner according to claim 1 or 2, wherein the pressure dependent valve is built in a plunger.

Images