Belt tensioner
AssigneeShowa Corporation
InventorKatsushi Tanaka
Life of this patent
Estimating the term…
Abstract
In a belt tensioner, a cylinder is mounted to a side of a stationary member positioned in an upper side. A plunger is mounted to a side of a pulley positioned in a lower side. An outer tube sectioning an oil reservoir forming a gas chamber in an upper portion is provided in an outer periphery of the plunger and the cylinder. A first oil passage communicating the gas chamber with a high pressure oil chamber is provided in an upper portion of the cylinder. A second oil passage communicating the high pressure oil chamber with the oil reservoir is provided in the plunger. An orifice hole is provided in the first oil passage. A first check valve closing at an expansion time is provided in the first oil passage, and a second check valve closing at a compression time is provided in the second oil passage.
Claims38
A belt tensioner positionable between a side of a stationary member and a side of a pulley, arranged and constructed to provide tension to a belt, comprising:
- a plunger slidably inserted into a cylinder;
- the cylinder being mountable to the side of the stationary member positioned in an upper side, and the plunger being mountable to the side of the pulley positioned in a lower side;
- a high pressure oil chamber sectioned by the cylinder and a pressurizer of the plunger being formed within the cylinder;
- an outer tube sectioning an oil reservoir forming a gas chamber in an upper portion being disposed in an outer periphery of the plunger and the cylinder;
- a first oil passage communicating the gas chamber with the high pressure oil chamber being disposed in an upper portion of the cylinder;
- a second oil passage communicating the high pressure oil chamber with the oil reservoir being disposed in the plunger;
- an orifice hole being provided in the first oil passage and a first check valve closing during expansion being disposed in the first oil passage;
- and
- a second check valve closing during compression being disposed in the second oil passage,
- wherein the outer tube comprises a dust boot attachable respectively to the side of the plunger and the side of the cylinder in upper and lower base end portions, and being expandable and contractable in an axial direction.
A belt tensioner positionable between a side of a stationary member and a side of a pulley, arranged and constructed to provide tension to a belt, comprising:
- a plunger slidably inserted into a cylinder;
- the cylinder being mountable to the side of the stationary member positioned in an upper side, and the plunger being mountable to the side of the pulley positioned in a lower side;
- a high pressure oil chamber sectioned by the cylinder and a pressurizer of the plunger being formed within the cylinder;
- an outer tube sectioning an oil reservoir forming a gas chamber in an upper portion being disposed in an outer periphery of the plunger and the cylinder;
- a first oil passage communicating the gas chamber with the high pressure oil chamber being disposed in an upper portion of the cylinder;
- a second oil passage communicating the high pressure oil chamber with the oil reservoir being disposed in the plunger;
- an orifice hole being provided in the first oil passage and a first check valve closing during expansion being disposed in the first oil passage;
- and
- a second check valve closing during compression being disposed in the second oil passage,
- wherein the second oil passage comprises a vertical hole open to the high pressure oil chamber and a transverse hole open to the oil reservoir, a recess portion formed in a side of a high pressure oil chamber in the vertical hole,
- the second check valve being receivable in a recess portion of the vertical hole, being arranged and constructed to be prevented from dropping out to an outer side by a cage-shaped stopper disposed in an opening portion facing the high pressure oil chamber of the recess portion, and comprising a ball valve which is movable close to or apart from a valve seat of the recess portion formed in a step portion between the recess portion and the vertical hole so as to be openable and closable.
A belt tensioner positionable between a side of a stationary member and a side of a pulley, arranged and constructed to provide tension to a belt, comprising:
- a plunger slidably inserted into a cylinder;
- the cylinder being mountable to the side of the stationary member positioned in an upper side, and the plunger being mountable to the side of the pulley positioned in a lower side;
- a high pressure oil chamber sectioned by the cylinder and a pressurizer of the plunger being formed within the cylinder;
- an outer tube sectioning an oil reservoir forming a gas chamber in an upper portion being disposed in an outer periphery of the plunger and the cylinder;
- a first oil passage communicating the gas chamber with the high pressure oil chamber being disposed in an upper portion of the cylinder;
- a second oil passage communicating the high pressure oil chamber with the oil reservoir being disposed in the plunger;
- an orifice hole being provided in the first oil passage and a first check valve closing during expansion being disposed in the first oil passage;
- and
- a second check valve closing during compression being disposed in the second oil passage,
- wherein a mounting member is fixable to a lower portion of the plunger, and the casing comprising the outer tube is independently formed from the mounting member and a dust boot comprising the outer tube is a cover formed by a press work piece, an oil seal is fitted in a liquid tight manner to an expanded opening portion disposed in a lower end opening of the cover, an upper end outer peripheral surface of the casing is insertable in a liquid tight manner to the oil seal of the cover, and the casing is in slidable contact with the oil seal of the cover.
Dependencies are inferred from the claim text.