FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)

“FOOT PEDAL POSITION SENSORY SYSTEM FOR MOTOR VEHICLE”

MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R & D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C., SATPUR,
NASHIK – 422 007,
MAHARASHTRA, INDIA.

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
FIELD OF THE INVENTION:-

This invention relates to a vehicle foot pedal position sensory system, typically of a motor car, incorporating a driver actuating pedal, such as a clutch pedal, brake or accelerator pedal.

BACKGROUND OF THE INVENTION:-

Traditionally, in a car with a manual transmission, clutch is operated by the driver, for Engine Management System the input from clutch pedal is obtained from contact switches such as plunger operated, micro switches etc. Some pedals utilize contact sensors such as rotary potentiometers to generate the control signal as the pedal pivots between various operational positions. One disadvantage with the use of contact sensors and switches are that they tend to wear over time, which can affect the accuracy of the control signal.

An example of a pedal incorporating a contact sensor electric control is shown in U.S. Pat. No. 5819593. The pedal assemblies include a pedal arm that is pivotally mounted within a housing that is supported by a vehicle structure. The pedal structure including a pedal arm pivotally mounted on the carrier and a potentiometer mounted on the carrier and operative to generate an output electrical signal proportioned to the extent of pivotal movement of pedal arm. The generator means includes a potentiometer mounted on the carrier whose setting is varied in response to pivotal movement of the pedal structure of the carrier.

Another example of a pedal with a contact sensor electric control is shown in U.S. Pat. No.5768946. A position sensor is nested into a cup-shaped portion of a molded pedal. The pedal directly drives the position sensor rotor, but the sensor is fully self contained and environmentally sealed. By nesting the sensor within the pedal, additionally, the pedal still retains sufficient width to be designed to have adequate strength. Typically, these sensor modules are potentiometers. The potentiometers are sensitive to dirt and other contaminants and thus must be provided in a sealed environment in order to operate properly. The sensor modules are thus, self-contained and are installed into the pedal housing as a sealed component. The sensor modules are expensive and bulky. The pedal housing must be specially designed to accommodate these large sensor modules, which is undesirable.

Unlike a non-contact pedal with integrated position sensor containing magnetic field generator and magnetic field sensor is shown in U.S. Pat. No. 6809512 in which the sensor requires and has to pass through several bulkhead mounting holes and bolts. Fasteners pass through magnet aperture to retain the magnets and pole pieces.

OBJECTIVE OF THE PRESENT INVENTION:-

A basic objective of the present invention is the provision of an improved vehicle foot pedal position sensing system.
Accordingly invention provides a foot pedal position sensory system for motor vehicle having turning clutch lever consists a blade having foot pad at one end and other end mounted on a pivot located in a motor vehicle pedal box secured in the conventional manner to the stationary support structure or bracket; either a sensor assembly made of hall sensors placed on the said clutch lever and a magnet placed on the said support structure/ bracket or a sensor placed on said support structure/bracket and a magnet placed on the said clutch lever; the said sensor and magnet placed closely with non contact relative movement; and the out put of the said hall sensor connected to engine stop start system and engine management system - torque management where the clutch pedal position is required for engine torque management and stop start engine restarts.

DESCRIPTION OF THE FIGURES:-

The invention is described with reference to accompanying drawing to understand clearly wherein:
Figure 1 is illustrated a perspective of a vehicle foot pedal, typically a clutch pedal;
Figure 2 shows perspective of clutch portion of pedal mounting showing clutch pedal held in the support means by axial pin with a non-contact sensor magnet on pedal shank and on the bracket a sensor.

DETAILED DESCRIPTION OF THE PRESENT INVENTION:-

In the present invention, it requires only four mounting holes for the sensor, of which two are pips meant for accurate placement of sensor. And the magnet needs only to runs over the non-contact surface for providing the accurate position of the pedal.
Considering for instance a clutch pedal, an application exists where the technologies employed in the system incorporate traditional hydraulic clutch system in conjunction with sensing the clutch position, where clutch pedal position determination is important.

The application is Engine Stop Start system and Engine Management System torque management where the clutch pedal position is required for engine torque management and stop start engine restarts.

For the above mentioned clutch pedal application, it is necessary for the system to be able to accurately measure the percentage travel of the clutch pedal. Prior art sensing methods use electrical contact technologies, such as potentiometers, to determine the position of the clutch pedal. The disadvantage of such methods is the associated inaccuracy caused by mechanical tolerance build-up between machined and fabricated parts outside the main actuating control element.

According to the first aspect of the invention, there is provided a system for sensing the position of a vehicle foot pedal, comprising an integrated non-contact sensor which has two hall elements incorporated on the same chip associated with a displaceable element of the pedal. And also the non-contact sensor is having increased durability with very light in weight. Since the present non-contact clutch position sensor requires no major alignment, hence it is simple in packaging aspects.

According to the second aspect of the invention, there is provided a control system for a motor vehicle, having a driver operatable clutch pedal, wherein a non-contact sensor is associated with an actuating element of the clutch pedal, with an electronic control circuit receiving positional information from the sensor

According to a third aspect of the invention, there is provided a motor vehicle incorporating a system in accordance with the first aspect, or a control system in accordance with the second aspect.

A clutch position sensor will detect the top of the travel of clutch pedal which is necessary for engine management system for the torque management. The trigger magnet is positioned on the moving part of clutch pedal and Hall sensor consisting of two Hall chips is positioned on non-moving part of the clutch pedal will be triggered during this part of the clutch travel.

The foot pedal position sensory system of the present invention offers the following advantages over the conventional method.
- Increased durability of the clutch position sensing sensor as conventionally a clutch micro switch was being used
- Lower cost as compared to the conventional switch which is used for sensing the clutch travel.
- This is an integrated sensor which has two hall elements incorporated on the same chip. This enables both top of the travel and bottom of the travel detection integrated into a single sensor which saves lot of packaging work.
- No Major Alignment issues observed as they are located by four points and out of these four, two are pips. The pip will help in locating the sensor at its correct position.
- No separate requirement of resilient member to create hysteresis effect in the pedal arm movement.
- No breakage of plunger – As the sensor is a non contact sensor there will be no damage due to mechanical contact like in contact switch which will result in damage to plunger.
- No exclusive housing required for the connector in the pedal assembly – as the sensor has flexible pigtail connector.
- The employment of a non-contact sensor advantageously eliminates the wear characteristics associated with mechanical micro switches or similar prior art systems. Whilst the use of the pedal positioning sensor system for the brake pedals provides the possibility of a "drive by wire" system for a road vehicle.

PREFERRED FEATURES OF THE INVENTION:-

The pedal is a clutch pedal and/or brake pedal. The non-contact sensor is a Hall Effect sensor. The magnetic element is the main actuating control element of the pedal.
The angular movement of the magnet member is converted to a voltage representing the position of the foot-pedal via non-contact sensing surface.
The output of this buffering circuitry is then output as an analogue voltage representing the position of the foot-pedal or is further conditioned and output digitally.
This position signal is then used by EMS for Engine Stop Start application or EMS -TM
The position signal is also used to provide instrumentation information to the driver of the car (for example as a warning tone or visual display).
The control circuitry is internal or external to the position sensing circuitry.
The various aspects of the invention thus provide: 1. electrically contact free monitoring of foot-pedal position; 2. foot-pedal angular displacement calculated by Magnet’s travel.

DESCRIPTION OF THE EMBODIMENT:-

The invention will now be described in greater detail, by way of example, with reference to the accompanying diagrammatic drawing.

In the figure1 is illustrated a vehicle foot pedal 1, typically a clutch pedal. The pedal 1 comprises a blade 2 carrying at one end a foot pad 3, with its other end mounted on a pivot 4 located in a motor vehicle pedal box secured in the conventional manner to support structure 5 such as the vehicle dash or crossbeam, whereby the pedal 1 is pivotable under the control of the driver.

Associated with the blade 2 is, in accordance with the invention, a non-contact sensor magnet 6 in figure 2 on pedal shank and on the bracket a sensor 7 in figure 2 which is hall effect type which is capable of sensing the position of the magnet 6 in the pedal shank and hence the clutch pedal 1.

As presented here, a non contact sensor utilizes magnet 6 on pedal shank to generate magnetic fields that vary as function of position and a sensor 7 in figure 2 to detect varying magnetic field to measure the position of the shank. The sensor is a Hall Effect device 7 in figure 2 is used to produce an electrical signal that is dependent upon the magnitude of the magnetic flux incident upon the device.

The Sensor 7 may be physically attached to the component to be monitored and move relative to the stationary magnet 6 as the component moves. Conversely, here the sensor 7 is stationary with the magnet 6 affixed to pedal shank to be monitored. In either case, the position of the component to be monitored can be determined by the electrical signal produced by the Hall Effect device 7. Hence, the pedal and sensor assembly 7 detects the motion of the pedal as it is depressed by the foot of a user.

As stated above, the sensor 7 and electronic control circuit are stationary while the magnet 6 moves about the axis. The electronic control circuit for processing the signals from Hall Effect devices. Since it is an integrated sensor 7 which has two hall elements incorporated on the same chip for the detection of both top of the travel and bottom of the travel which saves lot of packaging work. The Hall Effect device is electrically connected to the terminals.

The electrical terminals are designed for interconnection with standard mating connector. As the magnetic field generated by the magnetic field actuator 6 varies with angular motion about axis, the signal produced by two hall chips changes linearly, the output from each hall element is taken separately and the output of this is then output as a fixed analog voltage representing the position of the foot-pedal.

In other words, the magnetic field sensor 7 detects the variable magnetic field such that as the pedal shank rotates as the two hall chips generates an electric signal proportional to strength of the variable magnetic field, this signal is then output as a fixed analog voltage representing the top of travel and bottom of travel of the pedal arm. This analog signal is then sent to controller like EMS, Engine Stop Start.

WE CLAIM:-

1. A foot pedal position sensory system for motor vehicle having turning clutch lever consists a blade having foot pad at one end and other end mounted on a pivot located in a motor vehicle pedal box secured in the conventional manner to the stationary support structure or bracket; either a sensor assembly made of hall sensors placed on the said clutch lever and a magnet placed on the said support structure/ bracket or a sensor placed on said support structure/bracket and a magnet placed on the said clutch lever; the said sensor and magnet placed closely with non contact relative movement; and the out put of the said hall sensor connected to engine stop start system and engine management system - torque management where the clutch pedal position is required for engine torque management and stop start engine restarts.
2. A foot pedal position sensory system as claimed in claim 1 wherein the said hall sensor mounted on the said support structure or bracket and magnet is mounted on the said clutch lever blade/pedal shank turns non contact manner about axis vicinity to the stationery sensor.
3. A foot pedal position sensory system as claimed in claim 1 wherein the said hall sensor is mounted over the said clutch lever blade/pedal shank and stationery magnet mounted on the support structure or bracket such that the sensor turns non contact manner about the axis vicinity to the said magnet.
4. A foot pedal position sensory system as claimed in claim 1 to 3 wherein the said sensor comprises two hall sensor mounted on the chip of electronic control circuit.