JP2007016953A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic auto tensioner constituted to start to operate a hydraulic damper immediately after the start of an engine. <P>SOLUTION: A plunger 13, and a return spring 14 imparting outward projecting property to the plunger 13, are built in a cylinder chamber 12 of a housing 11. The housing 11 is provided with an oil feeding passage 16 communicating with a pressure chamber 15 formed behind the plunger 13. Packing 40 is provided in the pressure chamber 15 to reduce volume, and when starting the engine, the pressure chamber 15 is immediately filled with oil fed into the oil feeding passage 16. Hydraulic damper action is thereby exhibited from immediately after the start of the engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an auto tensioner that keeps the tension of a timing chain or timing belt for driving a camshaft constant.

  In general, in a chain transmission that transmits the rotation of the crankshaft to the camshaft using a timing chain (hereinafter simply referred to as a chain) or a timing belt, an adjustment force of an auto tensioner is applied to the slack side of the chain to increase the chain tension. I try to keep it constant.

  As the auto tensioner, a plunger in a cylinder chamber formed in the housing and a return spring for imparting outward protrusion to the plunger are incorporated, and the housing communicates with a pressure chamber formed on the back of the plunger. 2. Description of the Related Art Conventionally, an oil supply type is known in which an oil supply passage is formed and a pushing force applied to a plunger by an engine oil supplied from the oil supply passage into a pressure chamber is buffered.

  By the way, in the conventional oil supply type auto tensioner, since the oil in the pressure chamber returns to the oil pump when the engine is stopped, a small amount of oil is left in the pressure chamber.

  For this reason, when the engine is restarted, the oil pump discharge amount is small immediately after the engine is started, and it takes time until the oil is filled in the pressure chamber. There was a disadvantage that occurred.

  An object of the present invention is to provide an oil supply type auto tensioner that shortens the filling time of oil in a pressure chamber and exhibits a hydraulic damper action immediately after the engine is started.

  In order to solve the above-mentioned problems, in the present invention, a plunger and a return spring for imparting outward protrusion to the plunger are incorporated in a cylinder chamber formed in the housing, and the back portion of the plunger is incorporated in the housing. An auto tensioner is formed in which an oil supply passage communicating with the pressure chamber formed in the pressure chamber is formed, and the pushing force applied to the plunger by the oil supplied from the oil supply passage to the pressure chamber is buffered. Therefore, a configuration was adopted in which the volume of the pressure chamber was reduced.

  Here, the padding is formed into a cylindrical shape, a flange is formed on the outer periphery of the end of the columnar padding, and the padding is integrated with the plunger by applying a spring force of a return spring to the flange and pressing the padding against the plunger. Therefore, the generation of abnormal noise due to the collision of the filling can be prevented.

  In addition, by incorporating the cylindrical stuffing into the end of the return spring, it is possible to prevent the return spring from bending in the length direction, so-called bending of the return spring, and the return spring spring force Can always be loaded in the axial direction.

  As described above, since the volume in the pressure chamber is reduced by filling the pressure chamber, the oil filling time in the pressure chamber can be shortened. For this reason, when the engine is started, the pressure chamber is immediately filled with oil, and the hydraulic damper action is exhibited immediately after the engine is started, thereby preventing chain flapping.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a chain transmission for driving a camshaft, and a chain 5 is spanned between a sprocket 2 attached to an end of a crankshaft 1 and a sprocket 4 attached to an end of a camshaft 3. .

  A chain guide 6 is provided on the slack side of the chain 5. The chain guide 6 can swing about the shaft 7 and is pressed against the chain 5 by an adjusting force loaded from the auto tensioner 10.

  As shown in FIG. 2, the auto tensioner 10 has a housing 11 attached to the engine cover. A cylinder chamber 12 having a closed end is formed in the housing 11, and a plunger 13 and a return spring 14 that imparts outward protrusion to the plunger 13 are incorporated in the cylinder chamber 12.

  The housing 11 is provided with an oil supply passage 16 communicating with a pressure chamber 15 formed on the back of the plunger 13, and a check valve 17 is provided at an oil outlet portion of the oil supply passage 16. The check valve 17 closes the oil supply passage 16 when the pressure of the oil in the pressure chamber 15 becomes higher than the supply pressure of the oil sent to the oil supply passage 16.

  The plunger 13 is provided with a spring accommodating recess 18, a valve accommodating recess 19 and an oil discharge passage 20 in order from the rear end side located in the cylinder chamber 12, and the spring accommodating recess 18 is a part of the pressure chamber 15. And the tip of the return spring 14 is accommodated therein. The long return spring 14 can be employed by forming the spring accommodating recess 18, and the axial length of the housing 11 can be made compact.

  The oil drain passage 20 communicates the pressure chamber 15 with the outside. The oil discharge passage 20 is opened and closed by a relief valve 21 incorporated in the valve housing recess 19.

  Here, the relief valve 21 closes the oil discharge passage 20 when the oil pressure in the pressure chamber 15 is equal to or lower than the set pressure, and opens the oil discharge passage 20 when the pressure exceeds the set pressure.

  Between the housing 11 and the plunger 13, there is provided a backward movement restricting means 30 for preventing the plunger 13 from moving backward toward a closed end of the cylinder chamber 12 by a predetermined amount or more.

  As shown in FIG. 3, the backward movement restricting means 30 forms a ring accommodating groove 31 in the inner periphery of the opening of the cylinder chamber 12, and accommodates a register ring 32 that is elastically deformable in the radial direction in the ring accommodating groove 31. A plurality of circumferential grooves 33 tightened by the register ring 32 are provided at equal intervals in the axial direction on the outer periphery of the plunger 13, and a tapered surface having a smaller diameter toward the tip of the plunger 13 on the inner periphery of each circumferential groove 33. 33a and an engagement surface 33b extending radially outwardly from the small diameter end of the tapered surface 33a are provided.

  In the backward movement restricting means 30 configured as described above, when the plunger 13 moves outward by the pressing force of the return spring 14, the tapered surface 33a expands the diameter of the register ring 32. The plunger 13 moves outward due to the diameter expansion, and when a pushing force is applied to the plunger 13, the register ring 32 comes into contact with the rear wall 31 a of the ring receiving groove 31 and stops. The mating surface 33b is engaged and the plunger 13 is held in a stopped state.

  As shown in FIG. 2, a padding 40 is incorporated in the spring accommodating recess 18 formed in the plunger 13. The padding 40 has a columnar shape, and a flange 41 is provided on the outer periphery of the tip portion. The padding 40 is provided with an oil passage 42 penetrating from the front end surface to the rear end surface.

  The padding 40 is inserted into the end portion of the return spring 14, and the pressing force of the return spring 14 is applied to the flange 41 and pressed against the closed end of the spring accommodating recess 18.

  In the assembled state of the auto tensioner 10 as shown in FIG. 1, when the chain 5 vibrates due to a change in angular velocity during one rotation of the crankshaft 1 or a torque fluctuation of the camshaft 3, When the return spring 14 is pressed, the plunger 13 moves outward (moves forward) to absorb the slack of the chain 5.

  When the plunger 13 moves forward, the register ring 32 is pushed by the taper surface 33a to increase the diameter, and therefore does not hinder the forward movement of the plunger 13. When the movement amount of the plunger 13 becomes larger than the pitch of the circumferential groove 33, the next circumferential groove 33 corresponds to the register ring 32, and the circumferential groove 33 is tightened by the register ring 32.

  On the other hand, when the chain 5 is tensioned, a pushing force is applied to the plunger 13 via the chain guide 6. At this time, when the pressure in the pressure chamber 15 rises and the pressure becomes higher than the supply pressure of oil supplied from the oil pump to the oil supply passage 16, the check valve 17 closes the oil supply passage 16 and is enclosed in the pressure chamber 15. The pushing force applied to the plunger 13 is buffered by the hydraulic damper action of the oil.

  When the pressure in the pressure chamber 15 exceeds the set pressure of the relief valve 21, the relief valve 21 opens the oil discharge passage 20, and the oil in the pressure chamber 15 is discharged from the oil discharge passage 20 to the outside. For this reason, the chain 5 is prevented from being over-tensioned.

  When the engine is stopped, the oil pump is also stopped, so that the supply of oil to the oil supply passage 16 is interrupted.

  Immediately after the engine is stopped, the pressure in the pressure chamber 15 is high, so the check valve 17 closes the oil supply passage 16, but the oil in the pressure chamber 15 is minutely formed on the sliding surfaces of the cylinder chamber 12 and the plunger 13. Since the pressure leaks to the outside through a small gap, the pressure in the pressure chamber 15 gradually decreases, and the check valve 17 opens the oil supply passage 16 due to the decrease in pressure.

  Further, the check valve 17 may be opened due to an impact or the like when the door is closed. With the opening of the check valve 17, the oil in the pressure chamber 15 flows from the oil supply passage 16 to the oil pump side, and the inside of the pressure chamber 15. The amount of oil decreases.

  At this time, since the retracted position of the plunger 13 is restricted by the backward movement restricting means 30, only the amount of oil is reduced while the volume of the pressure chamber 15 is constant.

  For this reason, when the engine is started, since the discharge amount of the oil pump immediately after the start is small, it takes time until the pressure chamber 15 is filled with oil.

  However, as shown in the embodiment, by providing the padding 40 in the pressure chamber 15, the volume of the pressure chamber 15 can be reduced, so that the oil filling time for the pressure chamber 15 can be shortened. Can do.

  For this reason, when the engine is started, the pressure chamber 15 is immediately filled with oil, so that the hydraulic damper action is exhibited immediately after the engine is started, and it is possible to prevent the chain 5 from fluttering. .

  Further, the stuffing 40 is provided with a flange 41, and the stuffing 40 moves integrally with the plunger 13 by applying a pressing force of the return spring 14 to the flange 41 and pressing the stuffing 40 against the plunger 13.

  Therefore, there is no inconvenience that the stuffing 40 collides with the plunger 13 to generate an abnormal noise, and the stuffing 40 is incorporated in the end of the return spring 14 to prevent the return spring 14 from bending. In addition, since an unbalanced load is not applied to the plunger 13 from the return spring 14, the function of the hydraulic auto tensioner can be sufficiently exhibited.

Front view of a chain transmission device using a hydraulic auto tensioner according to the present invention 1 is a longitudinal front view of the hydraulic auto tensioner shown in FIG. Enlarged sectional view showing the backward movement restricting means

Explanation of symbols

11 Housing 12 Cylinder chamber 13 Plunger 14 Return spring 15 Pressure chamber 16 Oil supply passage 40 Stuffing

Claims (3)

  A plunger and a return spring that imparts outward protrusion to the plunger are incorporated in a cylinder chamber formed in the housing, and an oil supply passage that communicates with a pressure chamber formed on the back of the plunger is formed in the housing. In the auto tensioner configured to cushion the pushing force applied to the plunger by the oil supplied from the oil supply passage to the pressure chamber, the pressure chamber is filled to reduce the volume of the pressure chamber. Auto tensioner.   The autotensioner according to claim 1, wherein the padding is formed in a columnar shape, a flange is formed on an outer periphery of an end of the columnar padding, and the padding is pressed against the plunger by applying a spring force of a return spring to the flange.   The auto tensioner according to claim 2, wherein the cylindrical stuffing is incorporated in an end portion of a return spring.

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