JP2007303646A - Hydraulic automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain reduction in the service life of a hydraulic automatic tensioner, by preventing abrasion and deformation of a seat surface. <P>SOLUTION: A plunger 24 is arranged in a lower end part of a rod 16 in a cylinder 11 fitted with a sleeve 12, and a passage 27 is formed in the plunger 24. A check ball 32 is movably arranged to the seat surface 31 formed on the opening end on the pressure chamber 25 side of the passage 27, and when pushing-in force is applied to the rod 16, the passage 27 is closed by contacting the check ball 32 with the seat surface 31, and the pushing-in force is damped by a hydraulic fluid sealed in a pressure chamber 25. An elastic member 13 is incorporated between an under surface of the sleeve 12 and a bottom surface of the cylinder 11. The seat surface 31 is closed, and when pressure in the pressure chamber 25 starts to increase, the elastic member 13 is elastically deformed by axially moving the sleeve 12 by the pressure in the pressure chamber 25. The check ball 32 is prevented from being suddenly pressed to the seat surface 31, and abrasion and deformation of the seat surface 31 are prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner used for adjusting the tension of a belt for driving an auxiliary machine such as an alternator.

  As this type of hydraulic auto tensioner, one described in Patent Document 1 has been conventionally known. This hydraulic auto tensioner seals the upper end opening of the cylinder fitted with the sleeve by incorporating an oil seal to prevent leakage of hydraulic oil filled inside, and allows the oil seal to slide freely. An elastic force of a return spring is imparted to the penetrating rod to impart outward protrusion to the rod, and the belt is pressed by the rod to impart tension to the belt.

In addition, a plunger that is slidable along the inner diameter surface of the sleeve is provided at the lower end located in the sleeve of the rod, and a pressure chamber formed below the plunger and a reservoir chamber provided above the plunger are provided on the plunger. A communication passage is formed, a check valve is provided in the passage, and when a pushing force is applied from the belt to the rod, the check ball of the check valve is brought into contact with the seat surface formed at the opening end of the passage to close the passage. The pushing force applied to the rod is buffered by the hydraulic damper action of the hydraulic oil sealed in the pressure chamber.
JP 2001-289290 A

  By the way, in the hydraulic auto tensioner, the accessory driving belt constantly vibrates due to the fluctuation of the load. Therefore, when the check ball of the check valve repeatedly opens and closes and closes the passage by contacting the seat surface, The pressure on the sheet surface gradually increases and the surface pressure on the seat surface gradually increases.

  At this time, in the conventional hydraulic auto tensioner, the lower surface of the sleeve abuts against the bottom surface of the cylinder, and the sleeve is a non-movable support in the axial direction, so that the pressure in the pressure chamber increases rapidly. .

  FIG. 4 (II) shows a change in the generated load at that time, and the generated load increases rapidly as X, and an impact load is applied from the check ball to the seat surface by the rapid pressure increase. Become. Since this impact load is repeatedly applied, the seat surface easily wears and deforms, and the wear and deformation reduces the function of the check valve, which may reduce the life of the hydraulic auto tensioner.

  An object of the present invention is to prevent wear and deformation of a seat surface and to suppress a reduction in the life of a hydraulic auto tensioner.

  In order to solve the above problems, in the present invention, an oil seal for preventing leakage of hydraulic oil filled in the cylinder to the outside is incorporated in the upper end opening of the cylinder fitted with the sleeve, and the oil seal is installed. Plunger that slides along the inner diameter surface of the sleeve at the lower end located in the sleeve of the rod by applying the elastic force of the return spring to the slidably penetrating rod to give outward protrusion. The sleeve is partitioned into a pressure chamber and a reservoir chamber, and a seat surface is provided at the opening end of the pressure chamber side of the passage communicating the pressure chamber formed below the plunger and the reservoir chamber provided above, A check ball is movably provided on the seat surface, and when a pushing force is applied to the rod, the check ball is brought into contact with the seat surface to close the passage, In the hydraulic auto tensioner configured to cushion the pushing force applied to the rod by the hydraulic oil enclosed in the inside, the sleeve is made slidable, and an elastic member is incorporated between the lower surface of the sleeve and the bottom surface of the cylinder. The configuration was adopted.

  As described above, by incorporating an elastic member between the lower surface of the sleeve and the bottom surface of the cylinder, the check ball comes into contact with the seat surface by the pushing force applied to the rod, the passage is closed, and the pressure in the pressure chamber rises. When starting, the sleeve moves in the axial direction, the elastic member is elastically deformed, and the pushing load applied to the pressure chamber is buffered by the elastic deformation. For this reason, the check ball is not suddenly pressed against the seat surface, wear and deformation of the seat surface can be prevented, and the life reduction of the hydraulic auto tensioner can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a belt tension adjusting device. As shown in the figure, the pulley arm 1 is supported so as to be swingable about a fulcrum shaft 2, and a tension pulley 4 for applying tension to the belt 3 is rotatably supported at the end of the swing side. .

  The pulley arm 1 is connected to a hydraulic auto tensioner 10 according to the present invention, and the pulley arm 1 is urged by the hydraulic auto tensioner 10 in a direction in which the tension pulley 4 presses the belt 3.

  As shown in FIG. 2, the hydraulic auto tensioner 10 has a bottomed cylindrical cylinder 11 whose upper end is open. The cylinder 11 is made of an aluminum alloy, and a bottomed cylindrical sleeve 12 made of steel is slidably fitted therein, and rubber or α-gel (trade name) is provided between the lower surface of the sleeve 12 and the bottom surface of the cylinder 11. ) Or the like is incorporated.

  The cylinder 11 is filled with hydraulic oil. Further, the upper end opening of the cylinder 11 is sealed by incorporating an oil seal 14, and the oil seal 14 prevents leakage of hydraulic oil to the outside.

  The oil seal 14 is retained by a retaining ring 15 attached in the opening of the cylinder 11, and a spring seat 17 is provided at an upper end portion of the rod 16 slidably penetrating the retaining ring 15 and the oil seal 14 and positioned outside the cylinder 11. Is mounted, and a return spring 19 is provided between the spring seat 17 and a flange 18 provided at the lower outer periphery of the cylinder 11 to give the rod 16 outward protrusion.

  As shown in FIG. 1, a connecting piece 20 is formed on the upper surface of the spring seat 17, and the connecting piece 20 is connected to the pulley arm 1 via a bolt 21 screwed into the pulley arm 1. On the other hand, a connecting piece 22 is also provided at the lower end of the cylinder 11, and the connecting piece 22 is connected to the engine block via a bolt 23 screwed into an engine block (not shown).

  As shown in FIG. 2, a plunger 24 slidable along the inner diameter surface of the sleeve 12 is provided at the lower end portion of the rod 16 located in the sleeve 12, and the inside of the sleeve 12 is placed in the pressure chamber 25 by the plunger 24. And a reservoir chamber 26.

  The plunger 24 is formed with a passage 27 communicating with a pressure chamber 25 formed below and a reservoir chamber 26 provided above, and a check valve 30 is provided at the end of the passage 27 on the pressure chamber 25 side. Yes.

  As shown in FIG. 3, the check valve 30 includes a check ball 32 movably provided with respect to a seat surface 31 provided at the opening end of the passage 27, and a retainer that regulates the opening / closing amount of the check ball 32. The retainer 33 is press-fitted into the outer diameter surface of the protrusion 34 formed on the lower surface of the plunger 24.

  The check valve 30 is configured such that when the pressure in the pressure chamber 25 becomes higher than the pressure in the reservoir chamber 26, the check ball 32 contacts the seat surface 31 to close the passage 27.

  In FIG. 2, 35 indicates a plunger spring that presses the plunger 24 against the lower end of the rod 16, and 36 indicates a wear ring that slidably supports the rod 16.

  The belt tension adjusting device shown in the embodiment has the above-described structure, and the tension of the belt 3 changes due to the load fluctuation of the auxiliary machine driven by the belt 3 and the change of the angular velocity of the crankshaft, and the belt 3 is slack. When this occurs, the rod 16 moves outward due to the pressure of the return spring 19 and absorbs the slack of the belt 3.

  At this time, since the pressure in the pressure chamber 25 becomes lower than the pressure in the reservoir chamber 26, the check ball 32 is separated from the seat surface 31 to open the passage 27, and the hydraulic oil in the reservoir chamber 26 is discharged from the passage 27 to the pressure chamber. 25, the rod 16 and the plunger 24 rapidly move outward to absorb the slack of the belt 3 immediately.

  On the other hand, when the tension of the belt 3 increases, a pushing force is applied from the belt 3 to the rod 16. At this time, since the pressure in the pressure chamber 25 becomes higher than the pressure in the reservoir chamber 26, the check ball 32 contacts the seat surface 31 to close the passage 27, and the rod 16 is loaded with the hydraulic oil sealed in the pressure chamber 25. The pushing force is buffered.

  When the pushing force is larger than the elastic force of the return spring 19, the hydraulic oil in the pressure chamber 25 flows into the reservoir chamber 26 through a minute leak gap formed between the sliding surface of the sleeve 12 and the plunger 24. The rod 16 is slowly retracted to a position where the elastic force of the return spring 19 is balanced, and the tension of the belt 3 is kept constant.

  Here, when the pushing force is applied to the rod 16 and the check ball 32 comes into contact with the seat surface 31, the passage 27 is closed and the pressure in the pressure chamber 25 starts to rise, the sleeve 12 reaches the closed end of the cylinder 11. The elastic member 13 is elastically deformed. The pushing load applied to the pressure chamber 25 is buffered by the elastic deformation of the elastic member 13, and the generated load in the pressure chamber 25 is indicated by Y as shown in FIG. Will rise smoothly.

  In this way, by incorporating the elastic member 13 between the lower surface of the sleeve 12 and the bottom surface of the cylinder 11, the pressure in the pressure chamber 25 can be raised smoothly, so that the check ball 32 is suddenly applied to the seat surface 31. It is never pushed.

  For this reason, wear and deformation of the seat surface 31 can be prevented, and a decrease in the life of the hydraulic auto tensioner can be suppressed.

  In the embodiment, the passage 24 for communicating the pressure chamber 25 and the reservoir chamber 26 is provided in the plunger 24, but the lower portion of the reservoir chamber 26 and the lower portion of the pressure chamber are communicated between the fitting surfaces of the cylinder 11 and the sleeve 12. A passage may be provided, and a check valve may be provided at the end of the passage on the pressure chamber side.

Front view of belt tension adjusting device using hydraulic auto tensioner according to the present invention 1 is a longitudinal front view of the hydraulic auto tensioner shown in FIG. Sectional drawing which expands and shows the plunger part of the hydraulic auto tensioner shown in FIG. (I) is a graph showing the generated load in the pressure chamber of the hydraulic auto tensioner shown in FIG. 2, and (II) is a graph showing the generated load in the pressure chamber of the conventional hydraulic auto tensioner.

Explanation of symbols

11 Cylinder 12 Sleeve 13 Elastic member 14 Oil seal 16 Rod 19 Return spring 24 Plunger 25 Pressure chamber 26 Reservoir chamber 27 Passage 31 Seat surface 32 Check ball

Claims (1)

  An oil seal that prevents leakage of hydraulic oil filled in the cylinder is built into the top opening of the cylinder fitted with the sleeve, and the elastic force of the return spring is applied to the rod that slidably passes through the oil seal. In this way, a plunger that is slidable along the inner diameter surface of the sleeve is provided at the lower end located in the sleeve of the rod to partition the inside of the sleeve into a pressure chamber and a reservoir chamber. A seat surface is provided at the pressure chamber side opening end of the passage communicating with the pressure chamber formed below the plunger and the reservoir chamber provided above, and a check ball is movably provided on the seat surface; When a pushing force is applied to the rod, the check ball is brought into contact with the seat surface to close the passage, and the rod is loaded by the hydraulic oil sealed in the pressure chamber. In hydraulic auto-tensioner which is adapted to buffer the write power, the sleeve is slidable, hydraulic auto-tensioner, wherein incorporating the elastic member between the bottom surface of the lower surface and the cylinder of the sleeve.

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