DESC:FIELD OF DISCLOSURE
The present disclosure relates to the vehicle speed sensors.

DEFINITIONS
The expression “vehicle” used in the context of this disclosure refers but is not limited to automobiles, motorcycles, cars, jeeps, trucks, two wheeler vehicles, three wheeler vehicles, four wheeler vehicles, multi-wheeled vehicles, locomotives, rail vehicles and the like.

BACKGROUND
All vehicles include a speed indicator generally referred to as speedometer that displays the instantaneous speed of a vehicle. The speed of the vehicle is typically measured by speed sensors mounted in the vehicle. Speed sensors monitor the movement of vehicle components and acceleration. Speed sensors are usually either inductive or optical sensors and typically located at the transmission or transaxle of the vehicle. The sensors measure transmission/transaxle output or wheel speed. The information regarding the measured speed is typically provided to a vehicle control unit that uses this information to modify engine functions such as ignition timing, air-fuel ratio, transmission shift points, and to initiate diagnostic routines.

Different types of speed sensors are used depending on the type of vehicle control units and speedometers used in the vehicle. Some vehicles use analog speed sensors while some vehicles use digital speed sensors. Furthermore modern vehicles typically comprise multiple sensors mounted in the vehicle to control different components of the vehicle. For example vehicles with power steering use the speed sensor input to regulate power steering pressures for higher assist at slow speeds, making parking lot manoeuvres easier to perform. Vehicles with anti-lock brake system (ABS) use sensor information to determine when a wheel is locked up and releases pressure to that wheel to maintain directional stability. Some vehicle manufacturers use a rear axle mounted speed sensor for both ABS and computer related vehicle speed functions. Instrument Cluster (IC) and Hybrid Electric Cluster (HEC) modules use vehicle speed info for speedometer operation. However to achieve all the aforementioned features, different speed sensors are required including analog as well as digital type.

However, a major disadvantage of the use of speed sensors in vehicles is that the sensors can be damaged by moisture, excessive cooling and heating, transmission contaminates, and road debris. In addition to wear, these sensors may have metal contamination, gear damage, or exposure to water intrusion depending where the senor is located. Furthermore due to malfunctioning and/or failure of the sensors, the vehicle’s fuel economy gets affected, the vehicle can experience rough shifting, the speedometer can fluctuate drastically, and in some instances, the vehicle can be rendered inoperable.

Hence, there is need for a speed sensor that can be protected from external environment and can be used with analog as well as digital speedometers and vehicle control units for controlling multiple components of a vehicle.

OBJECTS
Some of the objects of the present disclosure aimed to ameliorate one or more problems of the prior art or to at least provide a useful alternative are listed herein below.

An object of present disclosure is to provide a speed sensor for sensing the speed of a vehicle that can be used with both analog and digital speedometers;

Another object of the present disclosure is to provide a speed sensor for sensing the speed of a vehicle that can be used with a wide variety of vehicle control units;

Still another object of the present disclosure is to provide a speed sensor that can remain undamaged from moisture, excessive heating/cooling, transmission contaminates, and road debris; and

Yet another object of the present disclosure is to provide a speed sensor that can improve vehicle fuel economy.

Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The speed sensor of the present disclosure will now be described with the help of the accompanying drawing, in which:

Figure 1 illustrates a conventional arrangement of analog speedometer in accordance with prior art.

Figure 2 illustrates an arrangement of a speed sensor in accordance with the present disclosure.

Figure 3 illustrates a schematic representation of a speed sensor in accordance with the present disclosure.

Figure 4 illustrates block representation of the speed sensor.

DETAILED DESCRIPTION
The speed sensor of the present disclosure will now be described with reference to the embodiment shown in the accompanying drawing. The embodiment does not limit the scope and ambit of the disclosure. The description relates purely to the examples and preferred embodiment of the disclosed method and its suggested applications.

The embodiment herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

Modern vehicles typically comprise at least one vehicle control unit that controls one or more of the electrical system or subsystems and other components of the vehicle. The speed sensor of the present disclosure can be used in vehicles wherein both analog and digital signals are required by a vehicle control unit to control different components of the vehicle.

All vehicles include a speed indicator generally referred to as speedometer for indicating the instantaneous speed of the vehicle. The speed of the vehicle is typically measured by speed sensors mounted in the vehicle. Speed sensors monitor movement of vehicle components and acceleration. Speed sensors are usually either inductive or optical sensors and typically located at the transmission or transaxle of the vehicle. The sensors measure transmission/transaxle output or rotation speed of the wheels of the vehicle and send that information to the speedometer for indicating the speed. The rotational speed measured by the sensors is communicated to the speedometer via speed drive cables.

Referring to figure 1, a conventional arrangement of analog speedometer (150) in accordance with prior art is shown. The analog speedometer (150) is connected to a speed drive cable (10) that rotates in proportion to the wheel speed of the vehicle. An insulation cover (20) surrounds the speed drive cable (10) for protecting the speed drive cable (10) from damages caused by external environment.

Based on the type of speedometer, typically electronic/digital or analog/mechanical, the speed sensor capable of transmitting corresponding signals is used. For electronic/digital speedometers, the speed sensor capable of transmitting digital signals is used whereas for analog/mechanical speedometers, the speed sensor capable of transmitting analog signals is used. The use of multiple speed sensors make the sensors vulnerable to moisture, excessive cooling and heating, transmission contaminates, road debris, water intrusion and the like and also affect the vehicles fuel economy.

Referring to figure 2, an arrangement of a speed sensor (110) in accordance with the present disclosure is shown. The speed sensor (110) comprises an input shaft (120), an output shaft (130), a sensor element (160) and a digital output terminal (140). The input shaft (120) is connected to a speed drive cable (40) covered with an insulation cover (50). The speed drive cable (40) is connected to the transmission of the vehicle generating rotational speed. The sensor element (160) converts the analog wheel speed into digital wheel speed data and the digital output terminal (140) is used for providing digital wheel speed data to a digital speedometer. The input shaft (120) and the output shaft (130) of the present disclosure are hollow tubes and telescopic coupling is used. Whereas, other forms like a stub, solid pipe and other coupling means such as using a key coupling, a universal joint or the like as thought by a person skilled in the art may be used.

The speed communicated via the speed drive cable (40) is provided to the analog speedometer (150) through the speed sensor (110) without affecting the speedometer performance. The output shaft (130) is used for providing connection to the analog speedometer (150). Thus, the speed sensor (110) arrangement of the present disclosure eliminates the need of mounting different types of sensors on different wheels of the vehicle.

Referring to figure 3, a schematic representation of the speed sensor (110) in accordance with the present disclosure is illustrated. The figure shows the packaged speed sensor (110) comprising the input shaft (120), the output shaft (130) and the digital output terminal (140). The output shaft (130) is adapted for interfacing with the analog speedometer (150).
The speed sensor (110) of the present disclosure can be used in vehicles that require both analog and digital signals. The speed sensor (110) of the present disclosure can be used with analog/mechanical speedometers as well as digital/electronic speedometers, engine control unit (ECU), electronic capacitor discharge ignition (CDI), inductive discharge ignition (IDI) and the like.

Figure 4 illustrates the block representation of the speed sensor (110). The figure shows the speed sensor (110) including the sensor element (160) connected with the input shaft (120) and the output shaft (130). The sensor element (160) senses analog wheel speed provided by the input shaft (120) and converts it into digital wheel speed of the vehicle. The sensor element (160) provides the digital wheel speed data through digital output terminal (140). The speed sensor (110) further includes a Radio Frequency (RF) circuit (170) for transmitting digital wheel speed data of the vehicle to the digital speedometers or other electronic modules requiring the digital wheel speed information. The RF circuit (170) is further connected to a power source (180) for supporting RF signal transmissions by the RF circuit (170).

Thus, the speed sensor (110) of the present disclosure can be used with analog speedometers, digital speedometers and vehicle control units, for controlling multiple components of the vehicle thereby saving costs and improving the reliability of the speedometer without affecting vehicle functionality requirement.

TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE

The technical advancements offered by the speed sensor of the present disclosure include the realization of:

• usability with both analog and digital vehicle control units/speedometers;

• usability with a wide variety of vehicle control units;

• remaining undamaged from moisture, excessive heating/cooling, transmission contaminates, and road debris; and

• improving vehicle fuel economy.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:1. A speed sensor adapted to receive analog signals of vehicle speed based on rotational output, the speed sensor comprising:
an input shaft for receiving analog signal adapted to communicate with a rotational wheel speed sensing element to receive rotational wheel speed;
an output shaft configured to be connected to an analog type mechanical speedometer for displaying vehicle speed signals;
a sensor element fitted within the housing of the sensor adapted to sense the analog wheel speed and convert it into digital wheel speed data; and
a digital output terminal adapted to transmit digital wheel speed data to devices of said vehicle in need of such data.
2. The speed sensor as claimed in claim 1, wherein the sensor element is connected to a Radio Frequency (RF) circuit adapted to transmit the digital wheel speed data, via a RF signal, to the digital speedometers or other electronic modules requiring the digital wheel speed information.
3. The speed sensor as claimed in claim 1, wherein the digital output terminal is configured to provide the wheel speed data either continuously or at predetermined intervals.
4. The speed sensor as claimed in claim 2, wherein the speed sensor includes a power source to support transmission of RF signals via the RF circuit.
5. The speed sensor as claimed in claim 1, wherein the output shaft and the sensor element work in tandem or independently to provide analog output and digital output respectively.