ELECTRIC THROTTLE GRIP
Field of invention
The present invention relates to electric throttle grip for controlling the speed in Ebikes, motorcycles and three wheelers, more particularly, the present invention relates an electric throttle grip with non-contact type dual output sensor having dual Hall element and single magnet integrated in handle bar which converts rotation angle into precise electrical signal.
Background of the present invention
Conventionally, in motorcycles contact type potentiometer is used as throttle position sensor which is mounted on carburetor or throttle body to measure rotation angle of Throttle. The potentiometer converts rotation angle of throttle into electrical signal which is used by Engine control unit to control ignition timing.
In potentiometers, the drawbacks such as wear and tear are more significant when used in throttle position sensor application due to increase safety and reliability requirements. As throttle is mostly used in a small range (up to 30°), the abrasion is biggest in this limited range. Before failure, nonlinear behavior can be observed due to wear of the resistive tracks and material buildup on wipers. The worst effect is exactly in the driving range in which sensor is used the most.
The harsh environmental conditions for throttle position sensors include high temperatures, vibrations and / shocks and exposure to various liquids and gases which can all lead to early failure of the potentiometers.
Finally, being a passive device, neither wire breakages and over voltage nor internal defects can be detected and communicated to the ECU by the potentiometers.
A non-contact type throttle position sensor resolves the above disadvantages of contact type Throttle position sensor, The non-contact type sensors have advantages such as no wear, more reliable, good signal to noise ratio, redundancy possible, wire breakage and

short circuit detection possible & Capable of diagnostic coverage to meet safety requirement.
The magnetic non-contact type throttle position sensors mounted on handle bar, and Mostly, the sensor is mounted inside throttle grip on handle bar which requires complicated design and construction of throttle grip.
US 2005/0251301 Al describes a throttle grip apparatus relates to a throttle grip apparatus provided with a throttle grip rotatably mounted on a tip of a steering bar; an interlocking portion penetrated through the steering bar; a magnet formed at an edge portion of the interlocking portion; and an angle sensor that senses change in magnetic field of magnet in non-contact manner so as to detect rotation angle of throttle grip based upon the detected value of the magnetic field change. The angle sensor is penetrated through a mounting hole formed in a predetermined position of the steering bar, and arranged opposite to the magnet.
In this prior art, special throttle grip needs to be developed for mounting magnet at the end of grip inside of handle bar. Assembly of sensor on handle bar is complicated requires predetermined mounting hole to be drilled on handle bar. Initial setting is required after mounting sensor and magnet assembly on handle bar for zero position.
US 2010/0162848A1 describes a throttle grip apparatus. A throttle grip apparatus is provided with ; a throttle grip rotatably mounted on a leading end of a handle bar of a vehicle ; a magnet rotatable together with the throttle grip; a detector for detecting variations in a magnetic field of the magnet in a non contact manner to detect a rotation angle of the throttle grip;and a frictional plate for generating a rotation load of the throttle grip. The frictional plate is disposed within the handle bar. Special throttle grip needs to be developed for mounting magnet inside of handle bar, assembly of sensor on handle bar is complicated. Manufacturing of Throttle grip becomes complicated.
The US Patent 2009/0201014A1 describes a twist grip control device, in particular for motor vehicles as shown in figure 2.

The device (1) comprises: a stator portion (2) which is stationary in operation, a rotor portion (3) which may be gripped and which is mounted such that it can be manually rotated about an axis (A-A) with respect to the stator portion (2),against the action of an opposing spring (13), a first and a second permanent magnet(11a , 11b) connected to the rotor portion (3) in respective separate angular fields about said axis (A-A) and adapted to generate respective predetermined angular distributions of magnetic field intensity about said axis (A-A) , first and second magnetic field sensors (14a, 14b) Connected to the stator portion (2) in respective separate angular positions about said axis (A-A), and associated with the first and second permanent magnets (11a,11b) respectively in order to provide, when the rotor portion (3) is rotated by a certain angle with respect to the stator portion (2), respective first and second electrical signals indicative of the relative angular position of the rotor portion (3).These signals are correlated with one another in a predetermined relationship.
a) Complicated design and construction of twist grip –
? Positional accuracy of magnet 1 and magnet 2 needs to be maintained which is critical.
? Semicircular shape of PCB is complicated for manufacturing and costly.
b) Correlation between signal 1 and signal 2 is not accurate as variations in magnetic flux density for 2 magnets are different.
c) Excessive errors are involved in synchronization of signal 1 and signal 2.

Objects of the invention
The main object of the present invention is to provide an electrical throttle grip.
Still another object of the present invention is to provide a low cost electric throttle grip which is easy to manufacture without compromising on high precision output performance.
Yet another object of the present invention is to use same electric throttle grip to provide redundant outputs to increase reliability of product.
One more object of the present invention is to derive two synchronized outputs (output 1 and output 2).

Summary of the invention
Accordingly, the present invention is directed to electric throttle grip, which substantially obviates one or more problems due to limitations and disadvantages of the related art. The electric throttle grip which mainly comprises of four major sub assemblies as follows: Throttle grip assembly, Magnet holder assembly, Sensor assembly and Case assembly. The magnet holder comprises of rare earth sector magnet with angle ?m > ?t placed inside a magnet holder at specified location. Where,
?m: angular length of sector magnet.
?t : angular movement of throttle grip.

Magnet holder freely rotates inside magnet holder case and torsion spring assists magnet holder to retain its initial position after the throttle grip is released. Throttle grip assembly comprises throttle grip and throttle pipe. Throttle pipe has slots for receiving protrusion of magnet holder. The throttle grip rotates along with throttle pipe and drives magnet holder.

Sensor Assembly comprises of two Hall elements precisely located inside IC-holder and electrically connected to a PCB. The signal is transmitted through wiring harness connected to PCB at opposite end. The IC holder is placed inside PCB body. The PCB body is further clamped to lower case by screws. A specified relation is maintained between both Hall elements and magnet. Throttle grip assembly, Magnet holder assembly and Sensor assembly are finally enclosed inside case assembly. The upper case and lower case are clamped to each other by screws.

The unique electric throttle grip eliminates one or more drawbacks of the prior art and provide a robust and simple design.

In an embodiment of the present invention, the electric throttle grip uses single sector magnet specially magnetized & dual Hall element. The construction of the throttle grip of the present invention reduces effect of assembly variations on output linearity of the electric throttle grip.

In still another embodiment of the present invention, there is no effect of assembly variations on output linearity of the electric throttle grip and best linearity is maintained over its entire operating range.

In yet another embodiment of the present invention, correlation between signal 1 and signal 2 is accurately maintained.

In a further embodiment of the present invention, synchronization of signal 1 and signal 2 is precisely maintained.

In a further more embodiment of the present invention, the electric throttle grip is serviceable in aftermarket and hence affordable.

In one more embodiment of the present invention, the electric throttle grip provides redundant outputs to increase reliability of throttle grip.

Brief description figures
Figures 1 and 2 shows electric throttle grip of prior art.
Figure 3 illustrates front, bottom and side view of electric throttle grip according to an embodiment of the present invention.
Figure 4 illustrates an exploded view of the electric throttle grip of according to an embodiment of present invention.
Figure 5a illustrates the cross-sectional view taken along axis A- A of electric throttle grip shown in figure 3.
Figure 5b illustrates the enlarged cross-sectional view taken along axis A- A of electric throttle grip shown in figure 3.
Figure 6 illustrates the enlarged cross-sectional view taken along axis B-B of electric throttle grip shown in figure 3.
Figure 7 illustrates basic construction of Magnet & its magnetization, of the present invention in which the angle ?m is > ?t.
Figure 8a illustrates the relation between magnetic flux density (Gauss) and the rotation angle of throttle grip illustrated in figure 4.
Figure 8b illustrates the relation between angular rotation & redundant electrical output of Electric throttle grip illustrated in figure 4.
Figure 8c illustrates the relation between Linearity error& the rotation angle, of Electric throttle grip illustrated in figure 4.

Detailed description of the invention
Accordingly, the present invention provides A Electric throttle grip used for governing the speed in two & three wheelers, which converts rotation angle into redundant electrical outputs.

An embodiment of the present invention provides an electrical throttle grip comprising:
Two Hall element and single magnet specifically arranged in RH handle bar switch to get two redundant, linear, independent output signals, A sector magnet with angular length of sector ( ?m) greater than angular movement of throttle grip (?t), with width “A” specifically selected to provide sufficient flux density to Hall element 19a and 19b , and specially magnetized with N and S poles, precisely located in slot provided in magnet holder 7, having projections 7a, 7b and stopper 7c which rotates between end stopper’s 6a & 6b provided in magnet holder case 6, and the projections 7a,7b engage with throttle pipe having two slots 2a and 2b,on which the throttle grip is fixed , any angular movement of the throttle grip assembly along axis x-x’ comprising of throttle pipe 2 and throttle grip 1 engaged with magnet holder 7 comprising magnet 8 , causes similar rotation of magnet holder 7 along axis x-x’ and precise angular movement of magnet with respect to Hall element 19a and 19b , This whole construction reducing effect of assembly variations on output linearity of the electric throttle grip.

In another embodiment of the present invention in the Hall element 19a and 19b are precisely located in IC holder 11, in such way that they are kept adjacent to each other to form a predetermined air gap between single magnet 8 and Hall element 19a and 19b.

In still another embodiment of the present invention the Hall element 19a and 19b are programmable type & programmed in specific manner to get two redundant, linear, independent output signals for ?t angular rotation of throttle grip.

In yet another embodiment of the present invention with two Hall element & single magnet were correlation between output signal 1 and output signal 2 is accurately maintained.

In a further embodiment of the present invention with two Hall element & single magnet were, synchronization of output signal 1 and output signal 2 is precisely maintained.

Referring now to the drawings, there is shown an illustrative embodiment of the invention Electric throttle grip. It should be understood that the invention is susceptible to various modifications and alternative forms; specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below.

The complete assembly of electric throttle grip is shown in figure 3. The Electric throttle grip will now be described in detail with reference to figures 4, 5 and 6. It mainly consists of four major sub assemblies as follows: Throttle grip assembly, Magnet holder assembly, Sensor assembly & Case assembly. The magnet holder consists of rare earth sector magnet with angle ?m>?t .The magnet is precisely located in slot provided in magnet holder. The magnet holder has projections 7a, 7b and stopper 7c which rotates between end stopper’s 6a & 6b provided in magnet holder case 6. The initial position ?t1 is ensured by stopper 6a & final position ?t2 is ensured by stopper 6b. A torsion spring of stainless steel material is used to provide resistance to rider, while rotation of throttle grip. One end of torsion spring is fixed in magnet holder case 6 & other end is located in magnet holder 7. The torsion spring assists magnet holder to retain its initial position after the throttle grip is released. The force of torsion spring is such that it gives same feel to rider as that of Mechanical throttle grip. The magnet holder case assembly is fixed in lower case 4 by M5 fasteners. Throttle Grip assembly consists of throttle grip and throttle pipe. Throttle pipe 2 has slots 2a and 2b for receiving protrusion of magnet holder 7a and 7b.The throttle grip rotates along with throttle pipe and drives magnet holder.

Sensor Assembly consists of 2 Hall element 19a and 19b precisely located in IC holder 11.The 2 Hall element 19a and 19b are placed adjacent to each other inside IC holder 11 and soldered to PCB 18. The PCB is located in PCB holder 13 and wiring harness 15 soldered to PCB at opposite end slides inside sensor body 10. O ring 12 provided circumferentially on PCB holder 13, provides necessary sealing form dust water etc. The rib 10a ensures precise location of sensor body inside lower case 4.

The fastener 20 ensures tight fixing of sensor body 10 with lower case 4.Finally upper case and lower case are assembled together with 2 nos. M5 fasteners 16 to form RH switch assembly.

Figure 7, illustrates basic construction of Magnet & its magnetization, of the present invention in which the angle ?m> ?t. The magnet can be of any rare earth material such as Ndfeb or SmCo. The magnet angular length is limited by angle ?m. Angle ?m is > ?t, and width “A” of magnet is specifically selected to provide sufficient flux to both Hall element 19a and 19b. The magnet is specially magnetized with N and S poles formed on magnet. Angle ?m/2 limits angular length of each pole N and S. The flux density of both N and S poles should be sufficient enough to operate the Hall element 19a and 19b.

With reference to figures 5 and 6 , as the throttle grip 1 rotates along with the throttle pipe 2, the magnet holder 7 rotates and hence the sector magnet 8 moves with respect to both Hall element 19a and 19b generating a variable magnetic field. When the magnet is at initial position ?t1 both Hall element 19a and 19b receive maximum negative flux density. As the magnet rotates and reaches its final position ?t2 both Hall element 19a and 19b receive maximum positive Flux density. Hall element 19a and 19b convert variable flux density into electrical voltage signal. The electrical voltage signal at any point of is the measure of throttle grip angular rotation. This voltage signal is transmitted to control unit through wiring harness. Depending upon this signal the ECU or MCU will decide to alter the ignition timing in Fuel injection bikes or alter the speed of vehicle in E-bikes respectively.

Figure 8a, illustrates the relation between magnetic flux density (Gauss) & the rotation angle of throttle grip illustrated in figure 4.

As the magnet 8 rotates from ßy to ßz, the Flux density output varies from -ve Bmax to +ve Bmax. It is observed from figure 8a, that the useful range is obtained for rotation angle ßy1 to ßz1 as we observe best linearity in this range. At the start and end of the graph the variations in flux density is maximum.

Figure 8b illustrates the relation between angular rotation ?t & redundant electrical output of Electrical throttle grip illustrated in figure 4. As the throttle grip rotates from ?t1 to ?t2, dual redundant outputs are received. Two outputs can be programmed independently in “N” no. of ways to get proportional /crossed outputs.

For e.g.; Output 1 varies from low to high i.e.; 0.5V to 4.5V and Output 2 varies from high to low i.e.; 4.5V to 0.5V. The two output signals cross each other at common point (?t’ angular rotation of throttle grip). At this point both Output 1 and Output 2 are same.

As the Hall element used is programmable type, both Hall element 19a and 19b receive same flux density at each point of angular rotation , but the electrical outputs from both the Hall element are different. It is observed that Output 1 is reverse of Output 2.Thus having two redundant outputs improves reliability of Electric throttle grip.

Figure 8c illustrates the relation between Linearity error& the rotation angle ?t, of Electric throttle grip illustrated in Figure 4. As observed from the graph the Linearity error of both outputs is < ± 1% over ?t1 to ?t2 angular rotation of throttle grip. As common magnet is used for generating magnetic field, any variations in magnetic flux density are common for both Hall element 19a and 19b.

Correlation between output signal 1 and output signal 2 is accurately maintained as same variations in magnetic flux density are applicable for both Hall element 19a and 19b due to single magnet.

Synchronization of output signal 1 and output signal 2 is precisely maintained.

Advantages of the present invention
The main advantage of the present invention is that it is capable of maintaining best linearity and does not have the effect of mechanical variations.

Another advantage of the present invention is that the linearity of sensor output signal is best over wide rotation angle. Another advantage of the present invention is that the correlation between output signal 1 and output signal 2 is accurately maintained as same variations in magnetic flux density are applicable for both Hall elements due to single magnet. Further synchronization of output signal 1 and output signal 2 is precisely maintained.

Another advantage of the present invention is it provides redundant output and increases reliability of product.

The present invention is described with reference to the figures and specific embodiments; this description is not meant to be construed in a limiting sense.

We Claim:
1. An electric throttle grip for motorcycle, comprising:
a throttle grip assembly comprising
a throttle pipe rotatably mounted on handle bar of the motorcycle and a throttle grip provided on the throttle pipe for manually rotating the throttle pipe; a throttle position sensing assembly comprising:
an first part and second part forming a casing encasing an inner end of the throttle pipe;
a magnet-holder secured with the throttle pipe so that the throttle pipe and the magnet holder is rotatable together about a common axis against a force of a torsion spring;
a sector magnet accommodated in a recess provided on the magnet holder;
a sensor assembly disposed in the second part of the casing, the sensor assembly comprising two magnetic field sensors located adjacent to each other so as to receive equal amount of magnetic flux at given angular position of the throttle pipe thereby providing two outputs indicative of the angular position of the throttle pipe.
2. An electric throttle grip as claimed in claim 1, wherein the inner end of the throttle pipe comprises a circular flange portion having a pair of slots.
3. An electric throttle grip as claimed in claim 2, wherein the magnetic holder comprises a pair of projections received in the pair of slots provided in the flange portion for securing the magnetic holder with the throttle pipe.
4. An electric throttle grip as claimed in claim 1, wherein an intermediate holder disposed in the casing, the intermediate holder comprising:
an interior for receiving the magnetic holder so that the magnet holder is rotatable inside the interior of the intermediate holder;
an exterior provided with a sensor locator having a cavity for accommodating the sensor assembly.
5. An electric throttle grip as claimed in claim 4, wherein the magnet holder is provided with a stopper adapted to cooperate with two angularly spaced apart end stoppers formed on the intermediate holder defining an initial position (t1) and a final position (tc) respectively so as to define angle of rotation (t) of magnet holder or throttle grip in which (t) = (t2) - (t1).
6. An electric throttle grip as claimed in claim 4, wherein the sector magnet accommodated in the magnet holder has angular length (m) and width (A) in that the angular length (m) is greater than angle of rotation (t).
7. An electric throttle grip as claimed in claim 4, wherein the recess accommodating the magnet is formed in the magnet holder at a location so that rotation of the magnet holder inside the intermediate holder between the initial position t1 and the final position t2 traverses the magnet over the sensor locator accommodating the sensor assembly.
8. An electric throttle grip as claimed in claim 4, wherein the sensor assembly is accommodated in the sensor locator so that the magnetic field sensors are located adjacent to each other in the direction of the width of the magnet so that both the magnetic field sensors receive equal amount of magnetic flux for each angular position of the magnet holder or the throttle grip.
9. An electric throttle grip as claimed in claim 4, wherein the second part of the casing comprises a hole for receiving the sensor locator of the intermediate holder and the sensor assembly.
10. An electric throttle grip as claimed in claim 1, wherein the sensor assembly comprises a sensor body accommodating two magnetic field sensors precisely
located on a integrated circuit (IC) holder which is soldered to a printed circuit board (PCB) and a PCB holder (13) for locating the PCB inside the sensor body or mounted on track form on sensor body.
11. An electric throttle grip as claimed in claim 4, wherein the magnetic field sensors are Hall elements or Magneto resistive elements or advance magnetic or electromagnetic elements
12. An electric throttle grip as claimed in claim 4, wherein the hall elements are configured so as to provide two redundant output signals i.e. output signal-1 and output signal-2 indicative of angle of rotation of the magnet holder and the throttle pipe.
13. An electric throttle grip as claimed in claim 4, wherein the intermediate holder is secured with the second part of the casing with the help of fasteners.
14. An electric throttle grip as claimed in claim 1, wherein the sensor assembly is secured with the second part of the casing with the help of a fastener.
15. An electric throttle grip as claimed in claim 4, wherein the first part of the casing is secured with the second part of the casing with the help of fasteners.
16. An Electric throttle grip as claimed in claim 1, wherein the Hall elements (19a ,19b) are programmable type and programmed so as to obtain two redundant, linear, independent output signals for angular rotation (9t) of throttle grip.
17. An Electric throttle grip as claimed in claim 1, wherein the casing is integrated with one or more switch modules for performing one or more functions or accessories of the motorcycles.
18. An Electric throttle grip as claimed in claim 17, wherein the first part and the second part of the casing is provided with slots/windows for disposing the sswitch modules.
19. An Electric throttle grip as claimed in claim 18, wherein the one or more switch modules are selected from Start module, Engine Kill switch module, and Mode switch module.
20. An electric throttle grip for motorcycle substantially as herein described with reference to the accompanying drawings.