FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Attack angle measuring device and method of measuring attack angle
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Ashfaque Ahmed Ansari & Sudhir M Sutar
all Indian nationals of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed.


FIELD OF INVENTION
This invention relates to the attack angle measuring device and particularly to the device used for measuring the attack angle of windshield having a curved surface with a curvature across the width of the vehicle.
BACKGROUND OF THE INVENTION
Windshield wiping mechanism is generally used in vehicles to wipe the windshield glass to make it free from water, dirt and dust.
A typical system for wiping a windshield includes a wiper blade and arm assembly. The arm is typically mounted to a pivot shaft which is reciprocally rotated by a mechanical linkage connected to a wiper motor. The resulting reciprocal rotation of the arm causes the wiper blade to wipe across the windshield. A second arm with a second wiper blade is frequently provided as well.
Wiper blade comprises a rubber wiping portion, a base to hold the rubber, and a means by which the wiper arm can be hooked to the blade. Since the wiper blade reciprocates across windshield, the attack angle changes with each stroke. The attack angle is the angle of inclination of the axis of wiping portion with respect to a normal to the surface of windshield. At the close (parking) position the attack angle is positive and at the open position it is negative. As the wiper blade reciprocates continuously, the attack angle changes from positive to negative and so on. If the attack angle variation is large, then there will be juddering of the wiper blade. So to minimize the "juddering", the wiper arm should be designed such that it compensates the variation of the windshield glass curvature and its fixture. To quantify the attack angle during design of wiper arm, the gauge is developed.
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OBJECTS OF INVENTION
The main object of this invention is to provide a device which will be used to measure the windshield wiper attack angle contributed by the wiper arm.
BRIEF DESCRIPTION OF INVENTION
The attack angle measuring devices in accordance with this invention comprises a base plate with studs, a holder for holding the wiper arm and a scale with pointer.
BRIEF DESCRIPTION OF DRAWINGS
Figure la, lb and lc shows the front, top and left side view of the "Attack angle measuring device" in accordance with this invention.
Figure 2 shows the diagram of the "Attack angle measuring device" mounted on vehicle in accordance with this invention.
DETAIL DESCRIPTION OF INVENTION WITH REFERENCE TO DRAWING
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Referring to figure 1 & figure 2,
The attack angle measuring device in accordance with this invention basically comprises a base plate (1) with three studs (2) mounted in triangular direction, a holder (7) with holding pin (8) for holding the wiper arm and a scale (3) with pointer (4). The base plate (1) is attached with three studs (2), which rest on the windshield glass (A). Another plate (6) with the engraved scale (3) is attached to the base plate (1) in vertical direction. A holder (7) with a holding pin (8) for hooking the wiper
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blade is pivotally connected to the vertical plate (6) with the aid of bush & bearing (5) so that vertical plate (6) with base plate (1) is free to rotate on its pivoting point. A pointer (4) is attached to holder (7) and project vertically to move across the scale. The three studs on the base plate rest on the windshield glass and base plate positioned parallel to surface of the windshield by rotating on the pivot point. The pointer attached to the holder moves across the scale to shows the angle by which the base plate is inclined. The wiper arm is hooked to holding pin of the device and the device is place on its base plate on the windshield. The base plate along with vertical plate will rotate on the pivot point so that three studs are touched on windshield. The base plate rotation is measured from the scale.
METHOD OF MEASURING THE ATTACK ANGLE
1. Mount the wiper arm (9) on the spindle (10) at parking position (B).
2. Hook the wiper arm (9) to the holding pin (8) of the attack angle measuring device.
3. Place the device on the windshield glass such that all three studs (2) are touching the windshield glass (A).
4. Observe the pointer (4) on the scale (3) and record the attack angle.
5. Rotate the device on the spindle (10) to open position (C). Observe the pointer (4) on the scale (3) and record the attack angle.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
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WE CLAIM
1. An attack angle measuring device for measuring the attack angle of wiper arm
on wind shield glass of the vehicle comprising:
a base plate with at least three studs;
a vertical plate with an engraved scale mounted to said base plate;
a holder for holding the wiper arm pivotally connecting to said vertical plate such that said vertical plate along with said base plate is free to rotate on a pivoting point; and
a pointer member attached to said holder and extending vertically to move across said engraved scale to indicate the angle by which the base plate is inclined with respect to the windshield.
2. The attack angle measuring device as claimed in claim 1, wherein said at least three studs are mounted in a triangular manner.
3. The attack angle measuring device as claimed in claim 1, wherein said holder comprises a holding pin to hold said wiper arm.
4. The attack angle measuring device as claimed in claim 3, wherein the holder with said holding pin is pivotally connected to said vertical plate by bush and bearing arrangement.
5. The attack angle measuring device as claimed in claim 1, wherein the at least
three studs attached to the base plate rests on the windshield glass to maintain the
position of said base plate parallel to the surface of said windshield.
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6. A method of measuring attack angle with a device as claimed in the preceding
claims comprising the steps of;
a) mounting of wiper arm on a spindle at closed position.
b) hooking said wiper arm to said holder of said device.
c) placing the device on the windshield glass such that all the studs are touching the windshield glass.
d) observing the pointer on the scale and recording the attack angle.
e) moving said wiper arm around the spindle to an open position.
f) observing the pointer on the scale and recording the attack angle.

7. The attack angle measuring device as hereinabove claimed is with reference to the accompanying drawings.
8. A method of measuring attack angle as described in the substantially as herein described with reference to accompanying drawings.

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Dated this 12m day of January 2009

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TATA MOTORS LIMITED By their Agent & Attorney
(Karuna Goleria) of DePENNING & DePENNING