JP2007218401A - Hydraulic type automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic type automatic tensioner which is highly reliable in the operation for the tensional variation of a belt, and shortens the whole length of the tensioner. <P>SOLUTION: In the hydraulic type automatic tensioner, working oil is stored in a cylinder 7 having a sleeve 6 inserted and fixed thereinto. The inside space of the cylinder 7 is partitioned into a pressure chamber 9 and a reservoir chamber 10 by means of a plunger 8 slidably inserted into the sleeve 6. The pressure chamber 9 and the reservoir chamber 10 are made to communicate with each other via a leakage clearance 17. The pressure chamber 9 and the reservoir chamber 10 are made to communicate via a passage 24 in which a check valve 18 is provided so as to allow only the flow of the working oil in the direction from the reservoir chamber side toward the pressure chamber side. A rod 11 is provided so as to integratedly move together with plunger 8. A return spring 16 is provided so as to energize the rod 11 in the direction to enlarge the volume of the pressure chamber 9. In this case, the check valve 18 is composed of: a hemispherical valve body 19 having a spherical seat surface; a valve seat 20 provided so as to come into contact with and separate from the valve body 19; and a retainer 21 for keeping the posture of the valve body 19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner used for maintaining tension of a belt that drives an auxiliary machine such as an alternator.

  An auxiliary machine of an automobile, for example, an alternator, a car air conditioner, a water pump, or the like has a rotating shaft connected to a crankshaft of an engine by a belt, and is driven by the engine through the belt. In order to keep the tension of this belt within an appropriate range, generally, a pulley arm that is swingable about a fulcrum shaft, a tension pulley that is rotatably attached to the pulley arm, and a direction in which the tension pulley is pressed against the belt. A tension adjusting device including a hydraulic auto tensioner that urges a pulley arm is used.

  As a hydraulic auto tensioner to be incorporated in this tension adjusting device, hydraulic oil is stored in a cylinder inserted and fixed to a sleeve, and the inside of the cylinder is divided into a pressure chamber and a reservoir chamber by a plunger slidably inserted into the sleeve. A rod that moves integrally with a return spring in a direction in which the volume of the pressure chamber expands is known (Patent Documents 1 and 2). In this auto tensioner, the rod moves to a position where the urging force of the return spring balances with the belt tension, thereby absorbing the belt tension fluctuation and keeping the belt tension within an appropriate range.

  In addition, the pressure chamber and the reservoir chamber communicate with each other through a first passage that forms a throttle. When the rod moves in a direction in which the volume of the pressure chamber decreases, the hydraulic oil in the pressure chamber passes through the first passage. Flows into reservoir chamber. At this time, since the flow rate of the hydraulic oil flowing through the first passage is limited, the rod moves slowly, and the belt tension is kept stable.

  Furthermore, the pressure chamber and the reservoir chamber communicate with each other via a second passage provided with a ball check valve that allows only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side, thereby increasing the volume of the pressure chamber. When the rod moves in the direction, hydraulic oil flows from the reservoir chamber side to the pressure chamber side through the ball check valve. Therefore, the rod quickly moves in the direction in which the volume of the pressure chamber increases, and absorbs the slack of the belt quickly.

  However, in ball check valves that use balls as the valve body, increasing the ball diameter and increasing the flow rate of the valve increases the inertia of the ball and decreases the responsiveness of the valve. If the responsiveness is increased, the flow area of the valve becomes narrow and the flow rate of the valve becomes insufficient. Therefore, in the conventional hydraulic auto tensioner using this ball check valve, when the ball diameter is increased to absorb the sudden slackness of the belt, the response to the minute tension fluctuation of the belt is lowered, while the belt If the ball diameter is made small in order to improve the response to minute tension fluctuations, there has been a problem that it is impossible to absorb the sudden slack of the belt.

The ball check valve is thick. Therefore, if the ball diameter is increased to absorb the sudden slack of the belt, it is necessary to lengthen the entire length of the hydraulic auto tensioner in order to avoid the plunger from interfering with the ball check valve at the stroke end.
JP-A-10-19099 JP-A-10-306860

  The problem to be solved by the present invention is to provide a hydraulic auto tensioner that can absorb rapid slack of the belt and is excellent in responsiveness to minute tension fluctuations of the belt.

  In order to solve the above problems, hydraulic oil is stored in a cylinder having a sleeve fixed therein, and the cylinder is partitioned into a pressure chamber and a reservoir chamber by a plunger slidably inserted into the sleeve to form a throttle. The pressure chamber is connected to the pressure chamber via a first passage, and the pressure chamber is connected to the reservoir chamber via a second passage provided with a check valve that allows only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side. In the hydraulic auto-tensioner provided with a return spring that connects the reservoir chamber to each other and moves integrally with the plunger, and urges the rod in a direction in which the volume of the pressure chamber increases. A hemispherical valve body having a spherical seat surface, a valve seat provided so as to be able to contact and separate from the valve body, and a retainer for maintaining the posture of the valve body It was.

  This hydraulic auto tensioner is preferably formed with a recess on the opposite side of the seat surface of the valve body.

  The hydraulic auto tensioner of the present invention has a check valve with a hemispherical valve body, so the inertia of the valve body is small, and even when the diameter of the valve body is increased to widen the flow path area of the valve, the valve response is excellent. high. Therefore, it is possible to absorb the rapid slack of the belt while ensuring the response to the minute tension fluctuation of the belt.

  Further, when the valve body has a recess on the opposite side of the seat surface, the inertia of the valve body is small, so that the responsiveness of the check valve is higher and the responsiveness to minute tension fluctuations of the belt is more excellent.

  FIG. 1 shows a tension adjusting device for a belt 1 for driving an automobile auxiliary machine. This tension adjusting device has a tension pulley 2 that contacts the belt 1 and a pulley arm 3 that rotatably supports the tension pulley 2, and the pulley arm 3 is supported so as to be swingable about a fulcrum shaft 4. The pulley arm 3 is connected to the hydraulic auto tensioner 5 according to the first embodiment of the present invention. The hydraulic auto tensioner 5 biases the pulley arm 3 and presses the tension pulley 2 against the belt 1.

  As shown in FIG. 2, the hydraulic auto tensioner 5 has a cylinder 7 in which a sleeve 6 is inserted and fixed, and hydraulic oil is stored inside the cylinder 7. On the other hand, a plunger 8 is slidably inserted into the sleeve 6, and the inside of the cylinder 7 is partitioned into a pressure chamber 9 and a reservoir chamber 10 by the plunger 8. Further, a rod 11 extending upward from the plunger 8 is connected to the plunger 8 so that the rod 11 and the plunger 8 move integrally. A spring seat 12 is attached to the upper end of the rod 11.

  An oil seal 13 that slidably penetrates the rod 11 and seals the hydraulic oil in the cylinder 7 and a retaining ring 14 that prevents the oil seal 13 from being detached are attached to the upper portion of the cylinder 7. A flange portion 15 is formed on the outer periphery of the cylinder 7, and a return spring 16 that urges the rod 11 in a direction to increase the volume of the pressure chamber 9 is incorporated between the flange portion 15 and the spring seat 12. Yes.

  The pressure chamber 9 and the reservoir chamber 10 communicate with each other via a leak gap 17 formed between the sliding surfaces of the sleeve 6 and the plunger 8. The leak gap 17 is very small, and the flow rate of the hydraulic oil flowing through the leak gap 17 is limited.

  A check valve 18 is press-fitted into the lower end of the sleeve 6. As shown in FIG. 3, the check valve 18 includes a hemispherical valve body 19 having a spherical seat surface, an annular valve seat 20 provided opposite to the valve body 19, and a posture of the valve body 19. The retainer 21 is held. This check valve 18 allows the flow of hydraulic oil in a direction that separates the valve body 19 from the valve seat 20, but prohibits the flow of hydraulic oil in the direction that presses the valve body 19 against the valve seat 20.

  On the other hand, a communication groove 22 is formed on the inner periphery of the cylinder 7 from the position of the upper end of the sleeve 6 to the inner bottom of the cylinder 7 as shown in FIGS. As shown, a communication groove 23 is formed from the communication groove 22 to the check valve 18 at the lower end of the sleeve 6. Therefore, a passage 24 that connects the pressure chamber 9 and the reservoir chamber 10 is formed between the sleeve 6 and the cylinder 7.

  Next, an operation example of the hydraulic auto tensioner 5 will be described.

  When the load on the auxiliary machine fluctuates and the tension of the belt 1 increases, the tension is transmitted to the hydraulic auto tensioner 5 via the pulley arm 3 and the pressure in the pressure chamber 9 increases. When the pressure in the pressure chamber 9 becomes higher than the pressure in the reservoir chamber 10, the hydraulic oil in the pressure chamber 9 flows into the reservoir chamber 10 through the leak gap 17. At this time, since the check valve 18 is closed, the hydraulic oil does not flow through the passage 24. As the hydraulic oil flows through the leak gap 17 in this way, the plunger 8 moves, and the tension pulley 2 moves to a position where the tension of the belt 1 and the urging force of the return spring 16 are balanced. At this time, since the flow rate of the hydraulic oil flowing through the leak gap 17 is limited, the tension pulley 2 moves slowly and absorbs the tension while keeping the belt 1 in a stable state.

  On the other hand, when the load of the auxiliary machine fluctuates and the tension of the belt 1 decreases, the pressure of the pressure chamber 9 decreases due to the urging force of the return spring 16. When the pressure in the pressure chamber 9 becomes lower than the pressure in the reservoir chamber 10, the check valve 18 is opened, and the hydraulic oil in the reservoir chamber 10 flows into the pressure chamber 9 through the passage 24. The plunger 8 is moved by the flow of the hydraulic oil, and the tension pulley 2 is moved to a position where the tension of the belt 1 and the biasing force of the return spring 16 are balanced. Therefore, the tension pulley 2 moves quickly and absorbs the slack of the belt 1 quickly.

  The hydraulic auto tensioner 5 has a semispherical valve body 19 of the check valve 18 so that the inertia of the valve body 19 is small, and when the diameter of the valve body 19 is increased to widen the flow passage area of the check valve 18, The check valve 18 operates sensitively to fluctuations in the pressure in the pressure chamber 9. Therefore, it is possible to absorb the sudden slackness of the belt 1 while ensuring responsiveness to minute tension fluctuations of the belt 1.

  Further, since the valve body 19 of the check valve 18 is hemispherical, the thickness of the check valve 18 is small even when the diameter of the valve body 19 is increased to widen the flow passage area of the check valve 18. Therefore, the plunger 8 hardly interferes with the check valve 18 at the lower end of the pressure chamber 9 at the stroke end where the volume of the pressure chamber 9 is minimized, and the overall length of the hydraulic auto tensioner 5 can be suppressed.

  The valve body 19 of the check valve 18 is preferably formed of ceramics or resin. In this case, the inertia of the valve body 19 becomes smaller than that in the case where it is made of steel, so that the check valve 18 operates sensitively to fluctuations in the pressure in the pressure chamber 9, and the hydraulic pressure against minute fluctuations in the tension of the belt 1. The responsiveness of the type auto tensioner 5 can be improved.

  Further, as shown in FIG. 5, the valve body 19 of the check valve 18 may have a shape having a recess 25 on the opposite side of the spherical sheet surface by press molding of a metal plate or injection molding of resin. In this way, the inertia of the valve body 19 can be further reduced, and the manufacturing cost of the hydraulic auto tensioner 5 can be suppressed.

  In the above embodiment, the leak gap 17 is used as a passage for forming a throttle between the pressure chamber 9 and the reservoir chamber 10, but the passage for forming the throttle may be provided by another method. For example, a through hole may be formed in the plunger so that the pressure chamber communicates with the reservoir chamber, and an orifice throttle or a choke throttle may be attached to the through hole.

  FIG. 6 shows a hydraulic auto tensioner 30 according to a second embodiment of the present invention. As in the first embodiment, the hydraulic auto tensioner 30 is configured such that a plunger 33 is slidably inserted into a sleeve 32 fixed in the cylinder 31, and the inside of the cylinder 31 is urged by the plunger 33 into the pressure chamber 34 and the reservoir chamber. It is divided into 35. The pressure chamber 34 and the reservoir chamber 35 communicate with each other via a leak gap 36 formed between the sliding surfaces of the sleeve 32 and the plunger 33.

  The plunger 33 is formed with a through hole 37 penetrating vertically, and the lower end of the rod 38 is inserted into the through hole 37. A communication groove 39 extending in the vertical direction is formed in the inner periphery of the through hole 37, whereby a passage 40 communicating the pressure chamber 34 and the reservoir chamber 35 between the rod 38 inserted into the through hole 37 and the plunger 33. Is formed. Further, since the spring 41 incorporated in the pressure chamber 34 presses the plunger 33 against the rod 38, the rod 38 moves integrally with the plunger 33.

  A check valve 42 is provided at the lower end of the plunger 33. As shown in FIG. 7, the check valve 42 holds a hemispherical valve body 43 having a spherical seat surface and the posture of the valve body 43. And a retainer 44. The retainer 44 is sandwiched between the spring 41 and the plunger 33, and moves integrally with the plunger 33 by the urging force of the spring 41. The plunger 33 functions as a valve seat that contacts and separates from the valve body 43.

  A spring seat 45 is attached to the upper end of the rod 38, and the rod 38 is urged between the flange portion 46 formed on the outer periphery of the cylinder 31 and the spring seat 45 in the direction of expanding the volume of the pressure chamber 34. A return spring 47 is incorporated.

  The hydraulic auto tensioner 30 also operates in the same manner as in the first embodiment. That is, when the belt tension increases and the pressure in the pressure chamber 34 becomes higher than the pressure in the reservoir chamber 35, the hydraulic oil in the pressure chamber 34 flows into the reservoir chamber 35 through the leak gap 36, and the plunger 33 moves. To do. At this time, since the flow rate of the hydraulic oil flowing through the leak gap 36 is limited, the tension pulley moves slowly and absorbs the tension while keeping the belt in a stable state.

  On the other hand, when the belt tension decreases and the pressure in the pressure chamber 34 becomes lower than the pressure in the reservoir chamber 35, the check valve 42 opens, and the hydraulic oil in the reservoir chamber 35 flows into the pressure chamber 34 through the passage 40. The plunger 33 moves. At the same time, the hydraulic oil in the reservoir chamber 35 flows into the pressure chamber 34 through the leak gap 36, so that the tension pulley moves quickly and absorbs the slack of the belt quickly.

  In the hydraulic auto tensioner 30, the valve body 43 of the check valve 42 is hemispherical as in the first embodiment, so that the inertia of the valve body 43 is small and the diameter of the valve body 43 is increased to increase the flow path of the check valve 42. Even when the area is increased, the check valve 42 operates sensitively to fluctuations in the pressure in the pressure chamber 34. Therefore, it is possible to absorb the rapid slack of the belt while ensuring the response to the minute tension fluctuation of the belt.

  Further, since the valve body 43 of the check valve 42 is hemispherical, the thickness of the check valve 42 is small even when the diameter of the valve body 43 is increased to widen the flow passage area of the check valve 42. Therefore, the check valve 42 at the lower end of the plunger 33 does not easily interfere with the inner bottom surface of the pressure chamber 34 at the stroke end where the volume of the pressure chamber 34 is minimized, and the overall length of the hydraulic auto tensioner 30 can be suppressed.

  The valve body 43 of the check valve 42 is preferably formed of ceramics or resin. In this case, the inertia of the valve body 43 is smaller than that of the case where it is made of steel. Therefore, the check valve 42 operates sensitively to the fluctuation of the pressure in the pressure chamber 34, and the hydraulic pressure is applied to the minute tension fluctuation of the belt. The responsiveness of the auto tensioner 30 can be improved.

The front view which shows the tension adjusting device incorporating the hydraulic auto tensioner of 1st Embodiment of this invention 1 is a sectional view of the hydraulic auto tensioner of FIG. 2 is an exploded perspective view of the sleeve and the check valve in FIG. Sectional view along line IV-IV in FIG. Sectional drawing which shows the modification of the check valve of FIG. Sectional drawing which shows the hydraulic auto tensioner of 2nd Embodiment of this invention FIG. 6 is an exploded perspective view showing the check valve of FIG.

Explanation of symbols

5 Hydraulic auto tensioner 6 Sleeve 7 Cylinder 8 Plunger 9 Pressure chamber 10 Reservoir chamber 11 Rod 16 Return spring 17 Leak gap 18 Check valve 19 Valve body 20 Valve seat 21 Retainer 24 Passage 25 Recess 30 Hydraulic auto tensioner 31 Cylinder 32 Sleeve 33 Plunger 34 Pressure chamber 35 Reservoir chamber 36 Leak gap 38 Rod 40 Passage 42 Check valve 43 Valve element 44 Retainer 47 Return spring

Claims (2)

  A hydraulic oil is stored in a cylinder 7 having a sleeve 6 fixed therein, and the cylinder 7 is partitioned into a pressure chamber 9 and a reservoir chamber 10 by a plunger 8 slidably inserted into the sleeve 6 to form a throttle. Via the second passage 24 provided with a check valve 18 that allows the pressure chamber 9 and the reservoir chamber 10 to communicate with each other through the passage 17 and allows only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side. The pressure chamber 9 and the reservoir chamber 10 are communicated with each other, a rod 11 that moves integrally with the plunger 8 is provided, and a return spring 16 that urges the rod 11 in a direction in which the volume of the pressure chamber 9 increases is provided. In the hydraulic auto tensioner, the check valve 18 includes a hemispherical valve body 19 having a spherical seat surface, and a valve seat 20 provided so as to be able to contact and separate from the valve body 19. , Hydraulic auto-tensioner, characterized in that is constituted by a retainer 21 for holding the posture of the valve body 19.   The hydraulic auto tensioner according to claim 1, wherein the valve body (19) has a recess (25) on the opposite side of the seat surface.

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