Inclinometer

1. Field of invention

This invention is related generally to an angle measuring instrument, and more particularly to a inclinometer of the type having a casing, a scale disposed within the casing and a locking device.

2. Description of prior art

Inclinometer can measure the angle between an object and a vertical line in the vertical plane. When using the inclinometer measuring the angle between two objects in a vertical plane, most of the time you have to measure the angles between the objects and vertical line, then calculate the two angle to get the angle between the two objects. It is very inconvenient to use that method. U.S. Pat. No. 4,656,752 discloses a precise-reading angular level that includes a casing, and a rotational protractor rotationally mounted in the casing, a plumbing swing angle indicator pivotally mounted in the casing. By using this device, the user can measure the angle between two objects with one measurement, but still has to manually adjust the inclinometer to zero before making the measurement. That method is inconvenient and may not be accurate due to the error made by manually adjusting it to zero.

It is an objective of the present invention to provide an improved inclinometer to measure the angle between the object and the vertical or horizontal line.

It is another objective of the present invention to provide an improved inclinometer to measure the angle between two objects.

It is another objective of the present invention to provide an improved inclinometer to measure the angle between two objects without calculation.

It is another objective of the present invention to provide that automatically adjust to zero.

It is another objective of the present invention to provide an improved inclinometer that is easy to use and more accurate to measure the angle between two objects.

It is another objective of the present invention to provide an improved inclinometer that is inexpensive easy to manufacture with.

The objective of the present invention is to provide an inclinometer which includes a casing, a gravitated rotational protractor, a pendulum swing angle indicator, a protractor rotation locking device and an object holding strip. By controlling the locking device, the protractor can be released to rotate freely, the pendulum swing needle and the gravitated rotational protractor will always rotate to the relatively same position (the needle point to "0" degree angle ). Then the locking device can lock the protractor at a fixed position, the needle continuing to rotate to measure the angle to which the inclinometer has been tilted.

FIG. 1 is a front view of the present invention;

FIG. 2 is a cross section of the present invention taken at plane 2--2 of FIG. 1;

FIG. 3 is an illustration showing the gravitated rotational protractor of the present invention;

FIG. 4 is a cross section of the protractor taken at plane 4--4 of FIG. 3;

FIG. 5 is a front view of pendulum swing angle indicator;

FIG. 6 is the front view of one embodiment of the protractor rotation locking device, the locking device located at a lateral edge of the protractor;

FIG. 7 is a cross section of another embodiment of rotational locking device taken at plane 2--2 of FIG. 1, the locking device located at a central position;

FIG. 8 is a front view of another embodiment of the present invention, using colored fluid as the angle indicator;

FIG. 9 is a front view of another embodiment of present invention, wherein the angle indicator is a colored ball;

FIG. 10 shows an application when using the present invention for measuring the inclination angle between two objects.

As shown in FIGS. 1-6, the present invention includes a casing, 20, which includes a front transparent plate 22a and a rear plate 22b, the front plate having am angular graduation 28 distributed both rightward and leftward from a central zero graduation on top, a protractor 30 rotationally mounted in the casing 20 at axis 32, a pendulum indicator or needle 40 rotationally mounted on axis 32 of the protractor 30, and a locking device 50 pivotally mounted in the casing 20 through axis 52.

The front plate 22a and rear plate 22b of the casing 20 form the flat bottom surface 24 having two slots, 23 at the left and 25 at the right. Two strips 27 and 29 pass through the corresponding slots. The front plate 22a is formed of transparent material. The rotational protractor 30, shown in FIGS. 3 and 4, made of light weight material such as plastic, has an axis 32 at the center. A weighted disc 34 is embedded on the lower portion of the protractor 30. An angle graduation 36 distributed both rightward and leftward from the central zero graduation coincides with indicator needle 46 while both the protractor and indicator are gravitationally pendant. The pendulum swing angle indicator 40 as shown in FIG. 5, having weight 44 located at one end and needle 46 at the opposite end, is pivotally mounted on the front axis 32a of the protractor 30 through the hole 42 between the weight 44 and needle 46. The locking device as shown in FIG. 6 includes a "V" shaped lever pivotally mounted in the casing at axis 52 located at the medial point of the lever, the lever having on either side of axis 52 one arm 56 extending to the lateral edge of the protractor 30 and another arm 54 having a button formed at the end of the arm 54, the button 58 protruding out of the casing 20 through the window 29 at a lateral side of the casing. A helical spring 51, supported at the axis 52, has one arm 51a mounted on the lever and another arm 51b mounted on the casing to prevent the lever from rotating.

FIG. 7 shows another embodiment of the present invention. A locking device located at the center axis includes a casing having a hole 26 at the center of the front plate 22a, a weighted rotational protractor 70 rotatably mounted on axis 60 in the casing 20, a pendulum swing angle indicator 40 rotatably mounted on a central forward protrusion 72 of the protractor 70, a locking spring 64 placed around the axis 60 located between the rear plate 22b of the casing and a protrusion 62. The axis 60 has control disc 66 located at its front end, the disc having an axial extension spring block protrusion located at approximately middle length of the axis. The disc extension passes through the medial hole 26 of the front plate 22a of the casing 20 and is pivotably mounted on the rear plate 22b. The rotational protractor 70 has a pivot hole 72 at the center to allow the disc extension to pass through. A weight 74 is located at the lower portion of the protractor.

FIGS. 8 and 9 show two other embodiments of the invention. A tube 80, supported on the front plate 22a partially surrounds the periphery of the protractor 30. When half of the tubing is filled with colored fluid 82, the surface line of the fluid 82 indicates the angular reading. When a colored ball 92 is placed in the empty tubing, the lowest point on the ball indicates the angle reading.

Referring now to FIG. 10, for a description of the use of this invention to measure the inclination angle between the surfaces of object A and object B. The bottom surface 24 is placed on the object A and may be fixed in position there by strips 27, 29. Depressing the button 58 or disc 66 frees the protractor 30 or 70 to freely rotate under the effect of gravity on the angle indicator needle 40 or colored fluid 82 or the colored ball 92. In this way the inclinometer adjusts to zero. Then by releasing the push button 58 or control disc 66, the protractor 30 or 70 will be locked in a fixed position. Next, the inclinometer bottom surface 24 is moved onto object B. The indicator needle 40, colored fluid 82, or colored ball 92 will rotate under the effect of gravity to show the inclination angle between object A and B.