Measuring and testing – Test stand – For engine
Reexamination Certificate
1998-12-07
2001-12-04
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Test stand
For engine
C073S117020, C073S117020, C073S114220
Reexamination Certificate
active
06324902
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an apparatus and method for inspecting a phase angle error of a camshaft for an internal combustion engine.
(b) Description of the Related Art
Generally, a camshaft is driven at one-half crankshaft speed in a four-stroke-cycle engine by either a gear, a chain and sprocket, or a cog belt and sprocket. The camshaft has as many cams as the number of intake and exhaust valves. The cams are formed at a predetermined phase angle to open and close the valves at a controlled rate of speed, as well as at precise times in relation to piston position.
Therefore, if the phase angle becomes mis-aligned when manufacturing the camshaft, precise valve timing cannot be attained, lowering the performance of the engine. It is therefore necessary to check the phase angle error of each camshaft. The following method is typically used to inspect the phase angle error.
The phase angle of a camshaft is measured by an apparatus and then compared with a design phase angle to determine if the camshaft is fit for use in an actual engine. A well known apparatus for measuring the phase angle is the three-dimensional measuring apparatus.
The three-dimensional measuring apparatus comprises a detector moving along X, Y and Z axes perpendicular to each other, and a measuring device that reads the amount of movement of the detector along the axes and measures a position and outer shape of an object. The phase angle of a camshaft can be measured using such a three-dimensional measuring apparatus.
However, the three-dimensional measuring apparatus is expensive. One reason for the high cost is that the three-dimensional measuring apparatus is designed to make various measurements (i.e., location, distance, outline, and shape) of numerous different objects in addition to the phase angle of camshafts. Also, the measuring process is complicated, increasing the amount of time needed to measure the camshaft phase angle, as well as requiring a skilled operator to perform the measurements.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in an effort to solve the above-described drawbacks.
It is an object of the present invention to provide an apparatus for inspecting a phase angle error of a camshaft, which is inexpensive and simple in structure.
It is another object of the present invention to provide a method for inspecting a phase angle of a camshaft, which can reduce the amount of time needed to take measurements.
It is still another object of the present invention to provide an apparatus for inspecting a phase angle of a camshaft, which is easy to operate.
To achieve the above objects, the present invention provides an apparatus for inspecting a phase angle error of a camshaft having a plurality of cams and a first location hole with a predetermined design phase angle with respect to the cams, the apparatus comprising a supporter for horizontally supporting the camshaft; a clamping member for fixing at least one reference cam of the camshaft at a predetermined angle; and a first inspecting member for inspecting an actual location of the first location hole of the camshaft, thereby inspecting a phase angle error of the camshaft.
If the camshaft has a second location hole having a predetermined design phase angle with respect to the cams, the apparatus may further comprise a second inspecting member for inspecting an actual location of the second location hole of the camshaft, thereby inspecting a phase angle error of the camshaft.
The apparatus may further comprise a horizontal base plate on which the supporter and the clamping member are fixed.
The supporter comprises a first block having a groove on which a first end of the camshaft is stably disposed, and a second block having a groove on which a second end of the camshaft is stably disposed.
The clamping member comprises a cam master having a recess complemental to a lobe of the reference cam, and a hydraulic pressure assembly for securely fixing the reference cam on the cam master by pressing a base circular portion of the reference cam.
The hydraulic pressure assembly comprises a hydraulic cylinder for generating pressing force, a press rod for transmitting the pressing force to the reference cam, and a press pad connected to the press rod to press the reference cam against the cam master.
Each of the measuring member comprises a check pin for checking the actual location of the location hole and a supporting plate for movably supporting the check pin such that the check pin moves toward a design location of the location hole, the design location of the location hole having the predetermined design phase angle with respect to the reference cam.
Each of the check pins comprises a first rod movably supported by the supporting plate, a second rod extending from the first rod and having a diameter equal to that of the location hole, and a taper rod extending from the second rod and tapered at a predetermined angle such that according to an amount of an insertion depth of the taper rod into the location hole, a deviation of the actual location of the location hole from the design location can be checked, thereby determining the phase angle error of the camshaft.
According to another aspect, the present invention provides a method for inspecting a phase angle error of a camshaft having first and second location holes each having a predetermined design phase angle with respect to a reference cam of the camshaft, comprising the steps of fixing the camshaft such that the reference cam cannot be moved; inserting a first checking member into the first location hole, the first checking member moving toward a design location of the first location hole; checking a deviation of an actual location of the first location hole from the design location in accordance with an amount of inserting depth of the first checking member into the first location hole; and determining if the camshaft passes or fails in accordance with an amount of the deviation of the actual location first location hole.
The method may further comprise the steps of inserting a second checking member into a second location hole, the second checking member moving toward a design location of the second location hole; checking a deviation of an actual location of the second location hole from the design location in accordance with an amount of inserting depth of the second checking member into the second location hole; and determining if the camshaft passes or fails in accordance with an amount of the deviation of the actual locations of the first and second location holes.
REFERENCES:
patent: 5024187 (1991-06-01), Bakker
patent: 5508944 (1996-04-01), Danielli
patent: 5529034 (1996-06-01), Sone et al.
Fuller Benjamin R.
Hyundai Motor Company
Stevens Maurice
LandOfFree
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