Patent Application
20090020088
The present application claims the benefit of patent application number 2007-175032, filed in Japan on Jul. 3, 2007, the subject matter of which is hereby incorporated herein by reference.
The present invention relates to a lash adjuster.
JP-A-2004-278377 discloses a lash adjuster and a valve apparatus of a background art. The lash adjuster includes a body and a plunger in a cylindrical shape, a pressure chamber is partitioned between the body, and a bottom portion of the plunger inserted into the body by increasing or reducing a volume at inside of the pressure chamber by a working fluid introduced into the pressure chamber, the plunger is moved in an axial direction, and a valve clearance in a valve apparatus of an internal combustion engine is automatically adjusted. A gap between an inner peripheral face of the body and an outer peripheral face of the plunger is constituted by a small clearance for leaking the working fluid from the pressure chamber, when the plunger is moved to a lower side relative to the body and the working fluid at inside of the pressure chamber is compressed, the working fluid at inside of the pressure chamber is made to flow out to an outer side of the pressure chamber by passing the small clearance, and a total length of the lash adjuster is slightly shortened.
The small clearance is requested to be controlled highly accurately in order to ensure a performance of the lash adjuster. However, there is a situation that the control of the gap between the inner peripheral face of the body and the outer peripheral face of the plunger is technically difficult and a productivity is poor. Particularly, when it is necessary to further narrow the gap between the inner peripheral face of the body and the outer peripheral face of the plunger by a request for downsizing the lash adjuster, a further deterioration in the productivity is concerned.
The invention has been accomplished based on the above-described situation and it has an object to promote a productivity by facilitating a gap control.
A lash adjuster of the invention comprises a body in a cylindrical shape and a plunger inserted to inside of the body. The plunger partitions a pressure chamber at inside of the body by being integrated to the body, and is moved in an axial direction at inside of the body by increasing or reducing a volume at inside of the pressure chamber by making a working fluid flow to inside of the pressure chamber or flow out from the pressure chamber. Further, between an inner peripheral face of the body and an outer peripheral face of the plunger, a spacer filling a gap between the two faces is interposed.
According to the lash adjuster of the invention, the spacer having a large control width is made to handle a gap control, and therefore, different from the background art, it is not necessary to strictly control a gap between the inner peripheral face of the body and an outer peripheral face of the plunger, the gap control is facilitated, and promotion of a productivity can be achieved.
A valve apparatus of the invention comprises a cam rotated by being transmitted with a power of an engine, a rocker arm pivoted in accordance with rotation of the cam, a cylinder head including a feeding path of making a working fluid flow and a lash adjuster of automatically adjusting a valve clearance of a valve inserted to the cylinder head. The cylinder head is recessed to be formed with a support hole at an upper face thereof and opened with an oil feeding port intersected with the filling path at an inner peripheral face of the support hole. The lash adjuster comprises a body in a cylindrical shape inserted to inside of the support hole of the cylinder head and a plunger pivotably supporting the rocker arm at an upper end portion thereof, inserted to inside of the body. The plunger partitions a pressure chamber at inside of the body by being integrated to the body, and is moved in an axial direction at inside of the body by increasing and reducing a volume at inside of the pressure chamber by making a working fluid flow to inside of the pressure chamber by passing the oil filling port from the filling path or making the working fluid flow out from the pressure chamber. Further, between an inner peripheral face of the body and an outer peripheral face of the plunger, a spacer filling a gap between the two faces is interposed.
Embodiments 1 through 5 specifying the invention will be explained in reference to the drawings as follows.
A lash adjuster 10 of Embodiment 1 details of which are shown in
As shown by
An outer peripheral face of the cylinder portion 22 of the body 20 is formed with an outer side recess portion 23 over an entire periphery thereof at a position opposed to the oil feeding port 83, further, an inner peripheral face of the cylinder portion 22 of the body 20 is formed with an inner side recess portion 24 in a constrained shape over an entire periphery thereof at a position opposed to the outer side recess portion 23. Further, the cylinder portion 22 of the body 20 is bored with a body hole 25 opened to the outer side recess portion 23 and the inner side recess portion 24.
On the other hand, the plunger 60 constitutes a shape of a bottomed cylinder raising a peripheral wall 62 in a shape of a circular cylinder from a peripheral edge of a bottom wall 61 in a circular shape, fitted to the body 20 and is made to be movable in an axial direction (up and down direction) while bringing an outer peripheral face thereof into sliding contact with an inner peripheral face of the body 20. An upper end portion (top portion) of the plunger 60 is formed with a support portion 63 in a semispherical shape engaged with and supporting one end portion of the rocker arm 90 and the support portion 63 is formed with a vertical hole 64 capable of supplying a working fluid to the rocker arm 90.
An inner portion of the plunger 60 is made to constitute a lower pressure chamber 65 surrounded by the bottom wall 61 and the peripheral wall 62, and an inner portion of the body 20 includes a high pressure chamber 26 between the bottom portion 21 and the bottom wall 61 of the plunger 60 (in correspondence with a pressure chamber of the invention). A center of the bottom wall 61 is formed with a communicating hole 66 for communicating the lower pressure chamber 65 and the high pressure chamber 26.
The high pressure chamber 26 is integrated with a retainer 92, the retainer 92 is pressed to a lower face of the bottom wall 61 of the plunger 60 by an urge force of a retainer spring 93 brought into contact with the bottom portion 21 of the body 20. Further, inside of the high pressure chamber 26 is provided with a check valve 94 in a spherical shape for opening and closing the communicating hole 66, and a valve spring 95 is interposed between the check valve 94 and the retainer 92. The check valve 94 is constituted to be normally urged to an upper side by the valve spring 95 and to be opened only when a hydraulic pressure at inside of the lower pressure chamber 65 is elevated more than a hydraulic pressure at inside of the high pressure chamber 26.
A position of the outer peripheral face of the plunger 60 opposed to the inner side recess portion 24 of the body 20 is formed with a recess portion 67 over an entire periphery thereof. Further, the peripheral wall 62 of the plunger 60 is formed with a plunger hole 68 for communicating the lower pressure chamber 65 and the recess portion 67 on an upper side of the body hole 25.
Now, the outer peripheral face of the peripheral wall of the plunger 60 is formed with a ring-like groove 69 over an entire periphery thereof. The ring-like groove 69 is installed at a height position on a lower side of the recess portion 67 and confined in a range of a thickness of the bottom wall 61. Further, the outer peripheral face of the peripheral wall 62 of the plunger 60 is mounted with one spacer 50 fitted to the ring-like groove 69.
In details, the spacer 50 is constituted as a plate in a shape of a circular ring made of a synthetic resin having heat resistance and predetermined elasticity of fluororesin (ethylene tetrafluoride (PTFE)) or the like. The spacer 50 is interposed in a gap between the inner peripheral face of the cylinder portion 22 of the body 20 and the outer peripheral face of the peripheral wall 62 of the plunger 60 in a compressed state while being fitted to the ring-like groove 69, whereas in a single product state, the spacer 50 is provided with a plate width of a dimension slightly larger than a separating distance between a groove bottom of the ring-like groove 69 and the inner peripheral face of the cylinder portion 22 of the body 20, in an integrated state, the spacer 50 is provided with a plate width of a dimension the same as the separating distance. Further, the inner peripheral face of the cylinder portion 22 of the body 20 and the outer peripheral face of the peripheral wall 62 of the plunger 60 are opposed to each other in parallel by being spaced apart from each other by a small clearance 40 therebetween in a state of interposing the spacer 50 between the two faces.
Further, the spacer 50 is notched to be formed with a flow path 51 for leaking a work fluid introduced into the high pressure chamber 26. The flow path 51 is constituted by notching a portion of an outer peripheral edge of the spacer 50 by a small amount in a rectangular shape, and the working fluid at inside of the high pressure chamber 26 is made to be able to flow out to the upper side by only passing the flow path 51. The opening dimension of the flow path 51 is determined in correspondence with an individual one of the lash adjuster 10.
Next, an operation of the lash adjuster 10 according to the embodiment will be explained. A portion of the work fluid flowing in the feeding path 82 is introduced into the lash adjuster 10 by successively passing the oil feeding port 83, the body hole 25, and the plunger hole 68 and is stored at inside of the lower pressure chamber 65 and the high pressure chamber 26. Further, when a cam 70 is rotated along with a cam shaft 71 transmitted with a power of an engine and the rocker arm is pressed from an upper side by a cam nose 72, the plunger is moved to a lower side relative to the body 20 by being pressed by the rocker arm 90, the working fluid flowing into the high pressure chamber 26 is compressed and a pressure at inside of the high pressure chamber 26 is elevated. In accordance with elevation of the pressure at inside of the high pressure chamber 26, a small amount of the work fluid at inside of the high pressure chamber 26 is moved up to meander through the gap between an inner peripheral face of the cylinder portion 22 of the body 20 and the outer peripheral face of the peripheral wall 62 of the plunger 60, passes through the flow path 51 of the spacer 50 and the small clearance 40, thereafter, made to flow into the lower pressure chamber 65 by way of the plunger hole 68. An entire length of the lash adjuster 10 is shortened slightly by an amount of the work fluid flowing out from inside of the high pressure chamber 26. Further, by elevating the pressure at inside of the high pressure chamber 26, the body 20 and the plunger 60 are integrated to be rigid and the lash adjuster 10 functions as a fulcrum of the operation of the rocker arm 90.
When the cam nose 72 is brought into a state of being directed to the upper side from a lowermost point in accordance with rotation of the cam 70, a force of pressing the rocker arm 90 is nullified, and the plunger 60 is pressed back to the upper side by the pressure at inside of the high pressure chamber 26 and the urge force of the retainer spring 93. When the pressure at inside of the high pressure chamber 26 is lowered to be lower than the pressure at inside of the lower pressure chamber 65 in accordance with movement of the plunger 60 to the upper side, the check valve 94 is opened against the urge force of the valve spring 95, the work fluid introduced into the lower pressure chamber 65 is made to flow into the high pressure chamber 26 by passing the communicating hole 66 and the entire length of the lash adjuster 10 is expanded. By the operation of expanding the lash adjuster 10, a gap is prevented from being brought about between the support portion 63 of the plunger 60 and the rocker arm 90.
According to Embodiment 1, by interposing the spacer 50 between the inner peripheral face of the cylinder portion 22 of the body 20 and the outer peripheral face of the peripheral wall 62 of the plunger 60 and making the work fluid at inside of the high pressure chamber 26 flow out from the flow path 51 provided at the spacer 50, the gap control is made to be handled by the spacer 50 having a large control width, and therefore, different from the background art, the gap between the inner peripheral face of the cylinder portion 22 of the body 20 and the outer peripheral face of the peripheral wall of the plunger 60 may not be controlled strictly and promotion of a productivity can be achieved. As a result, the lash adjuster 10 can be downsized.
Particularly, the flow path 51 is formed at the spacer made of a synthetic resin, and therefore, a working performance of the flow path 51 is facilitated and a dimensional accuracy of the flow path 51 can be promoted in comparison with a case of being formed at the body 20 or the plunger 60 made of a metal. In this case, only one of the flow path 51 is formed at the spacer 50, and therefore, the dimensional accuracy is further promoted.
Further, the ring-like groove 69 for fitting the spacer 50 is provided at a position in correspondence with the bottom wall 61 of the plunger 60, and therefore, the groove depth is not particularly restricted by the thickness of the peripheral wall 62, for example, the groove bottom face can also be disposed on the side of the bottom wall 61, and a degree of freedom of design is promoted.
Otherwise, the flow path may be provided at the outer peripheral face of the peripheral wall 62 of the plunger 60, or may be provided by penetrating the bottom wall 61 of the plunger 60 partitioning the high pressure chamber 26 and the low pressure chamber 65. In this way, with regard to a mode of installing the flow path, a certain latitude may be provided to a variation, and therefore, by selecting a pertinent mode in accordance with a situation, a function characteristic of the lash adjuster 10 can sufficiently be achieved.
Further, a plurality of rectangular flow paths may be notched to be formed at an outer peripheral edge of a spacer.
Further, various modes of the flow paths of Embodiments 1 through 5 may mixedly be utilized such that a rectangular flow path and a circular flow path are mixedly provided to the outer peripheral edge of the spacer.
The invention is applicable to an internal combustion engine of a gasoline engine, a diesel engine or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-175032 | Jul 2007 | JP | national |
