Title of Invention

A DEVICE FOR MEASURING THE STEERING PARAMETERS OF A VEHICLE

Abstract

The device according to this invention comprises an adjustable telescopic arrangement with an outer tube and an inner tube said telescopic arrangement having a first end and a second end. The first end of said telescopic arrangement is attached to vehicle body part (windscreen) and the second end of the telescopic arrangement is attached to the roter of the steering sensor. The telescopic arrangement has a ball and socket joint on its first end connected to a vacuum suction cup. The vacuum suction cup has a ball and the telescopic arrangement has a socket. The socket is positively connected to the outer tube of the telescopic arrangement. Also, since the arrangement according to the present invention comprises an adjustable telescopic shaft, the difference in distance that is caused due to the vacuum cup operation (that caused the sag in the prior art) is compensated by keeping the bolt/screw loose while fixing the vacuum cup and then tightening the bolt/screw, thereby maintaining a positive mechanical coupling between the rotor and the windshield which prevents hysterisis losses.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; rule 13) TITLE OF THE INVENTION A Device for Measuring the Steering Parameters of a Vehicle 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 Pradyumna V. Kulkarni an Indian national 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 Complete specification particularly describes the invention and the manner in which it is to be performed. 1 Field of Invention The present invention relates to a device for measuring the steering parameters of a vehicle such as the steering angle and the steering torque. Background of the Invention An Instrumented Steering Wheel arrangement is used to measure parameters such as steering angle and steering torque. In order to sense the angular rotation of the steering wheel a multi-turn rotary potentiometer sensor is provided. In order to measure the steering torque a strain gauge based torque sensor arrangement is provided. The torque is a resultant of all the frictional forces starting from the road-wheel interface through the rack and pinion gears up to the steering column bearings. In order to supply power to the sensor and to transfer the data from the sensor to the data acquisition system, there is a slip-ring arrangement provided. US patent 6, 402, 196 discloses such an instrumented steering wheel comprising a torque sensor integrated or directly mounted in its armature. Also, prior US patents US 4,860,457, US 4,907,668 and US publication no. 2005/0182575 provide a background regarding the various devices and methods of measuring the torque and steering angle of a vehicle. Essentially, the instrumented steering wheel contains a stator and a rotor. The stator of the sensor is mechanically coupled to the steering column of the steering wheel of the vehicle and the rotor of the sensor is connected to another vehicle component, usually the windscreen. A positive coupling should be provided for both these parts. Usually, this is done by adapting the stator of the sensor to the steering column using caliper or other mechanical arrangements and fixing the rotor of the sensor to the windscreen using vacuum cup and a string or wire rope. By virtue of the 2 elasticity property of the wire rope and the mounting principle of the vacuum cup, some amount of hysterisis is rendered in the device, and in turn in the measurements. In cases of fastening one end of the wire rope to the windshield and another end to the rotor of the steering wheel sensor, sag is created in the wire rope that generates sufficient amount (up to 13%) hysterisis in the measurements. The amount of hysterisis also increases with the increased rate of angular motion of the steering wheel. Wire ropes, due to aging effect, have a tendency to get hard and the hardness causes difficulty in tying knots at either ends. Once used for a test, the same wire rope cannot necessarily be used for the second time. The present invention offers a solution to the above-mentioned disadvantage by providing a device for hysterisis free steering parameters measurements in vehicles. Summary of the Invention The present invention provides a device for measuring the steering parameters comprising an adjustable telescopic arrangement with an outer tube and an inner tube said telescopic arrangement having a first end and a second end. The inner tube may have either radial or axial or both movements with respect to the outer tube. The first end of said telescopic arrangement is attached to a vehicle body part (usually the windscreen) and the second end of the telescopic arrangement is attached to the rotor of the steering sensor, which is provided at the rear of the steering wheel. The telescopic arrangement has a ball and socket joint on its first end connected to a vacuum suction cup. The vacuum suction cup has a ball and the telescopic arrangement has a socket. The socket is positively connected to the outer 3 tube of the telescopic arrangement. The vacuum suction cup is preferably attached to the windscreen of the vehicle. Further, the outer tube has a radial tap of a suitable size. A bolt / screw of the tap size runs through the outer tube up to the inner tube to facilitate adjustment of the telescopic arrangement for various applications. Further the said adjustment can also be done by having external threads on inner tube and respective tapping on outer tube. The second end of the telescopic arrangement is the extension of the inner tube depending on the length of the telescopic arrangement required for the application, which also comprises a socket to be connected to a further ball joint. The second end of the telescopic arrangement is positioned eccentrically or offset from the center with respect to the center-to-center distance from the steering wheel and the vacuum cup arrangement. This invention also provides a method of mounting the device for measuring the steering parameters of the vehicle comprising the following steps: connecting the vacuum cup (7) is connected to the vehicle body, preferably to wind screen (8); connecting the socket (1) to the ball of vacuum cup (7); connecting the socket (5) to the ball of rotor side (9); adjusting the telescopic arrangement (T) by rotating the ball fitted on the rotor side (9), such that it maintains an offset distance with respect to the centre-to-centre distance from the steering wheel (5) and the vacuum cup (7); fastening the bolt / screw (3b) to provide a rigid linkage arrangement for maintaining a positive mechanical coupling between the rotor and the wind screen (8). 4 Due to the ball and socket arrangement at both ends, the device according to this invention can be easily mounted and dismounted. As a result, the instrumentation time for the vehicle under test, man hours and in turn the testing time can be greatly reduced. Data from the sensors can be acquired, transmitted and monitored using the data acquisition system and displayed using data displaying means as is known in the art. The instrumented data acquisition system is the aggregate of the sensing devices, which may be installed in its entirety or specific parts to monitor the steering performance. The present invention is interested in providing a novel device for measuring the various steering parameters so that the data collected, monitored and displayed by the data acquisition means is more accurate by reducing or eliminating losses, such as hysterisis loss. Brief Description of the Drawings 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, Fig 1A & IB shows the prior art device for measuring the steering parameters of a vehicle Fig 2 shows the hysterisis loop graph between actual and measured load with respect to prior art. Fig 3 shows the telescopic arrangement according to the main embodiment of this invention 5 Fig 4 shows the device incorporating the telescopic arrangement according to the present invention. Detailed description of the drawings The figure 1A and IB illustrates the existing device for measuring the steering parameters of a vehicle. The device according to the prior art comprised a string/wire rope (R) whose one end was fixed to the rotor ball joint (6) of the steering wheel sensor and the other end would be knotted to a vacuum cup (7) after determining the approximate length between the rotor and the windshield. Sufficient amount of tension is applied to the string and the vacuum cup (7) would then be attached to the windshield (8). Vacuum cup fixture works on the principle of adhesion using vacuum pressures. A lever (L) is applied to pull the vacuum cup (7) at the center in order to create partial vacuum. The distance from the vacuum cup (7) center to the ball joint on the rotor of the instrumented steering wheel decreases on pushing the lever. This produces a sag in the wire rope (R). This sag generates a sizeable amount of hysterisis in the measurements. The amount of hysterisis also increases with the increased rate of angular motion of the Steering wheel. Figure 2 shows the behavior of the load as a hysterisis loop, after the vacuum cup is fixed to the windshield using a string. To overcome this obvious disadvantage, the present invention discloses a novel device that eliminates the hysterisis drawback as will be discussed in detail below. Figure 3 illustrates the device according to this invention wherein it comprises rigid telescopic shaft (T) having an outer tube (2) and a coaxial adjustable inner tube (4) extending from within the outer tube (2) to an adjustable distance away from the outer tube (2), as is clear from figure 3. The outer tube (2) of the telescopic shaft (T) 6 contains a radial tap (3 a) of a suitable size at a distance from both the ends of the rigid telescopic shaft. A bolt / screw (3b), preferably an Allen bolt, of the same size of the tap runs through the outer tube (2). The telescopic shaft has a first and second end, wherein each end comprises a socket (1,5) that is joined to a ball joint. The socket joint (1) positively joined at the first end is connected to a vacuum suction cup (7) (fig 4) and the socket joint (5) at the second end is positively joined to the rotor side of the steering wheel sensor (fig 4). Figure 4 shows the detailed working construction of the device according to this invention. The vacuum suction cup (7) is fixed to a vehicle body part, usually the windscreen (8), by the principle of adhesion by vacuum pressure. The vacuum suction cup (7) shall have a ball arrangement and the first end of the rigid telescopic shaft shall be provided with the socket arrangement (1). Similarly, the rotor side (9) of the steering sensor shall have a ball arrangement to be joined with the socket arrangement (5) of the second end of the rigid telescopic shaft (T). The ball and socket joint on the rotor side (9) of the telescopic arrangement is kept off-center with respect to the center-to-center distance from the steering wheel (S) and the vacuum cup (7) arrangement as can be seen in figure 4. This deliberate offset from the center axis is maintained to negate all hysterisis effects. The vacuum cup (7) is first tightened on to the windshield by pushing the lever (L) and the instrumented steering wheel is fitted to the steering column. Then the first and second ends of the rigid telescopic shaft arrangement is fixed at the respective ends of the ball joints of the vacuum cup and the rotor side of the steering sensor. The bolt / screw (3b) is then tightened to ensure a rigid and hysterisis-free coupling arrangement to measure the steering parameters measurements such as steering angle and steering torque. Also, since the arrangement according to the present invention comprises an adjustable telescopic shaft, the difference in distance that is 7 caused due to the vacuum cup operation (that caused the sag in the prior art) is compensated by keeping the bolt / screw (3b) loose while fixing the vacuum cup and then tightening the bolt/screw (3b), thereby having a rigid linkage arrangement and maintaining a positive mechanical coupling between the rotor and the windshield which prevents hysterisis losses. The device according to this invention can be reliably used for multiple occasions, unlike the conventional method of tying wire ropes or strings, which have a property to break or warp and cannot necessarily be used for a second time. Due to the ball and socket arrangement at both ends, the invention can be very easily mounted and dismounted. As a result, instrumentation time, man-hours etc. are considerably reduced. 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. 8 Claim: 1. A device for measuring the steering parameters of a vehicle by acquiring and communicating signals from angle and torque sensors to the data acquisition system said device comprising a rigid telescopic shaft (T) having a first end and a second end; said telescopic shaft comprising an outer tube (2) and a coaxial adjustable inner tube (4) extending from within the outer tube (2) and up to an adjustable distance away from said outer tube (2); said first and second end of the telescopic shaft being positively connected to a socket joint (1,5) that is coupled to a corresponding ball joint at either ends; the socket joint (1) positively coupled at the first end is connected to a vacuum suction cup (7) and the socket joint (5) at the second end is positively coupled to the rotor side (9) of the telescopic arrangement; and the ball and socket joint on the rotor side (9) of the telescopic arrangement is maintained at an offset distance with respect to the center-to-center distance from the steering wheel (S) and the vacuum cup (7) arrangement to eliminate hysterisis effect. 2. The device as claimed in claim 1, wherein the said vacuum cup (7) is fixed to a vehicle body part, preferably the windscreen (8), by the principle of adhesion by vacuum pressure. 3. The device as claimed in claim 1 or 2, wherein the outer tube (2) of the telescopic shaft (T) has a radial tap (3 a) of a suitable size at a distance from both the ends of the rigid telescopic shaft to accommodate a bolt or screw 9 (3b) to facilitate adjustability of the inner tube (4) with respect to the outer tube (2), thereby having a rigid linkage arrangement and maintaining a positive mechanical coupling between the rotor and the windshield to eliminate hysterisis loss. 4. The device as claimed in claims 1 to 3 wherein the inner tube (4) may have external threads and outer tube (2) may have respective tapping to facilitate adjustability of the inner tube (4) with respect to the outer tube (2), thereby having a rigid linkage arrangement and maintaining a positive mechanical coupling between the rotor and the windshield to eliminate hysterisis loss. 5. The device as claimed in claims 1 to 4, wherein the inner tube (4) may have either radial or axial or both movements with respect to the outer tube (2). 6. The device as claimed in claim 2, wherein the vacuum cup (7) is fixed to the windshield by means of a lever (L) that is operably connected to the vacuum cup (7). 7. The device as claimed in claim 1, wherein the socket joints (1) and (5) can be interchangeably connected to ball of a vacuum cup (7) or rotor side (9). 8. The method of mounting the device for measuring the steering parameters of the vehicle as claimed in any of above said claims wherein the said method comprises the steps of: connecting the vacuum cup (7) is connected to the vehicle body, preferably to wind screen (8); connecting the socket (1) to the ball of vacuum cup (7); connecting the socket (5) to the ball of rotor side (9); 10 adjusting the telescopic arrangement (T) by rotating the ball fitted on the rotor side (9), such that it maintains an offset distance with respect to the centre-to-centre distance from the steering wheel (5) and the vacuum cup (7); fastening the bolt / screw (3b) to provide a rigid linkage arrangement for maintaining a positive mechanical coupling between the rotor and the wind screen (8). 9. A device for measuring the steering parameters of a vehicle and the method of mounting the said device substantially as herein described with reference to figs. 3 and 4 of the accompanying drawings. Dated this 18th day of December 2006 TATA MOTORS LIMITED By their Agent & Attorney (Karuna Goleria) of DePENNING & DePENNING 11 ABSTRACT ("A Device for Measuring the Steering Parameters of a Vehicle") The device according to this invention comprises an adjustable telescopic arrangement with an outer tube and an inner tube said telescopic arrangement having a first end and a second end. The first end of said telescopic arrangement is attached to a vehicle body part (windscreen) and the second end of the telescopic arrangement is attached to the rotor of the steering sensor. The telescopic arrangement has a ball and socket joint on its first end connected to a vacuum suction cup. The vacuum suction cup has a ball and the telescopic arrangement has a socket. The socket is positively connected to the outer tube of the telescopic arrangement. Also, since the arrangement according to the present invention comprises an adjustable telescopic shaft, the difference in distance that is caused due to the vacuum cup operation (that caused the sag in the prior art) is compensated by keeping the bolt / screw loose while Fixing the vacuum cup and then tightening the bolt / screw, thereby maintaining a positive mechanical coupling between the rotor and the windshield which prevents hysterisis losses. (Fig 3) 12

Documents:

2068-MUM-2006-ABSTRACT(12-6-2009).pdf

2068-MUM-2006-ABSTRACT(13-2-2009).pdf

2068-mum-2006-abstract(granted)-(3-5-2010).pdf

2068-mum-2006-abstract.doc

2068-mum-2006-abstract.pdf

2068-MUM-2006-CANCELLED PAGES(12-6-2009).pdf

2068-MUM-2006-CANCELLED PAGES(13-2-2009).pdf

2068-MUM-2006-CLAIMS(12-6-2009).pdf

2068-MUM-2006-CLAIMS(13-2-2009).pdf

2068-mum-2006-claims(granted)-(3-5-2010).pdf

2068-mum-2006-claims.doc

2068-mum-2006-claims.pdf

2068-mum-2006-correspondance-received.pdf

2068-MUM-2006-CORRESPONDENCE(12-6-2009).pdf

2068-MUM-2006-CORRESPONDENCE(13-2-2009).pdf

2068-MUM-2006-CORRESPONDENCE(2-1-2007).pdf

2068-MUM-2006-CORRESPONDENCE(29-3-2010).pdf

2068-MUM-2006-CORRESPONDENCE(IPO)-(20-7-2009).pdf

2068-mum-2006-correspondence(ipo)-(4-5-2010).pdf

2068-mum-2006-description (complete).pdf

2068-MUM-2006-DESCRIPTION(COMPLETE)-(12-6-2009).pdf

2068-MUM-2006-DESCRIPTION(COMPLETE)-(13-2-2009).pdf

2068-mum-2006-description(granted)-(3-5-2010).pdf

2068-MUM-2006-DRAWING(12-6-2009).pdf

2068-MUM-2006-DRAWING(13-2-2009).pdf

2068-mum-2006-drawing(granted)-(3-5-2010).pdf

2068-mum-2006-drawings.pdf

2068-MUM-2006-FORM 1(12-6-2009).pdf

2068-MUM-2006-FORM 1(18-12-2006).pdf

2068-MUM-2006-FORM 18(2-1-2007).pdf

2068-mum-2006-form 2(12-6-2009).pdf

2068-mum-2006-form 2(13-2-2009).pdf

2068-mum-2006-form 2(granted)-(3-5-2010).pdf

2068-MUM-2006-FORM 2(TITLE PAGE)-(12-6-2009).pdf

2068-MUM-2006-FORM 2(TITLE PAGE)-(13-2-2009).pdf

2068-mum-2006-form 2(title page)-(granted)-(3-5-2010).pdf

2068-MUM-2006-FORM 3(13-2-2009).pdf

2068-MUM-2006-FORM 5(13-2-2009).pdf

2068-MUM-2006-FORM 8(13-2-2009).pdf

2068-MUM-2006-FORM 9(2-1-2007).pdf

2068-mum-2006-form-1.pdf

2068-mum-2006-form-2.doc

2068-mum-2006-form-2.pdf

2068-mum-2006-form-26.pdf

2068-mum-2006-form-5.pdf

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