"•field of the invention

This invention relates to the field of mechanical throttle system for the vehicles with spark ignition engines.

Background of the invention

Engine speed limitation and governing is done to limit the speed of vehicles and to prevent damage to the components of engine. Moreover, engine/ vehicle speed limitation off late has taken the shape of a regulatory framework in many countries, owing to safety issues and the need to restrict the speed of a particular class of vehicles. While speed limitations for system with electronic throttle control are well known, there exists a need to implement a similar strategy in case of mechanical throttle system for the vehicles with spark ignition engines also. In the case of systems fitted with mechanical throttle control, speed limitation is done by enabling fuel cut-off from the injector upon receiving feedback from the control unit. This abrupt fuel cut-off from the injector gives a momentary jerky feeling to the driver, as the engine is devoid of fuel for a short interval of time. Once normal fuel supply resumes, the driver again experiences a jerky feeling, till the fuel supply to the engine is stabilized. On the contrary, in an electronic throttle system, for speed limitation, the throttle is actuated directly by the control unit without the interference of the driver thereby providing a smooth driving experience.

Hence there is a need to actuate the throttle, by a suitable mechanism or device that simulates the effect of electronic control in the mechanical throttle system used in two wheelers.
US patent publication, US-20120090575 talks about an electronic throttle valve to control the amount intake air in internal combustion engine. The apparatus has a motor for driving an electronic throttle valve to adjust an amount of intake air in an internal combustion engine. A control unit generates an electric power supply command to the motor based on angle information detected by an angle detection unit i.e. angle sensor, and supplies electric power to the motor through an electric power supply unit. The control unit generates the command after detection of the Engine speed abnormality, based on the throttle angle information before detection of the engine speed abnormality.

Brief description of the accompanying drawings

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawings:

Figure 1 illustrates a device for controlling speed in a mechanical throttle system;

Figure 2 illustrates an actuating mechanism for throttle adjustment, and

Figure 3 illustrates a method for controlling the mass flow rate of air passing through the intake path of an engine.

Detailed description of the embodiments
Figure 1 illustrates a device 100 for controlling speed in a mechanical throttle system. The device 100 disclosed herein is connected to a first input cable 101 on one side and to a mechanical throttle on the other side by a second cable 102. The device 100 is enclosed within a housing 110. The device 100 comprises a hollow cylindrical shaft 103 with internal threads 103a and at least a partially threaded 103b outer surface forming a pinion. A first shaft 104 with threads complementary to internal threads 103a of the hollow cylindrical shaft 103 is positioned coaxially within the hollow cylindrical shaft 103 and adapted to translate to and fro in the hollow shaft along a fixed guide 105. The first shaft 104 slides along the fixed guide 105 through a slot located on the first shaft 104. The guide 105 helps to maintain the assembly of first shaft 104 and the hollow cylindrical shaft 103, and also prevent the first shaft 104 from over-travel. A second shaft 106 is provided with threads 106a adapted to couple with the pinion formed on the outer surface of the hollow cylindrical shaft 103. An actuator 107 is adapted to drive the second shaft 106. The second shaft acts like a rack so as to couple with the pinion formed on the hollow cylindrical shaft 103. The hollow cylindrical shaft 103 is fitted such that it can rotate freely but cannot translate and the first shaft 104 is fitted such that it can translate along the guide but cannot rotate. The rotation / translation of the second shaft 106 is adapted to cause rotation of the hollow cylindrical shaft 103. The rotation of the hollow cylindrical shaft 103 results in translation of first shaft 104 along the fixed guide 105 within the hollow cylindrical shaft 103 thereby changing the effective length of the cable to open and/ or close the throttle based on the positional feedback of the throttle conveyed from a position sensor 108 to a control unit 109. The position sensor 108 is mounted on a throttle body. The length of the fixed guide 105 is a function of the throttle opening between maximum and minimum opening position. That is, for one single traverse of the first shaft 104 along the fixed guide 105, the throttle would have opened in the interval of 0% (completely closed) to 100% (fully open) or the maximum opening can be restricted to have <100% based on the speed limitation strategy.

During working of the device 100, the first input cable 101 is generally linked to the accelerator of the vehicle and is actuated by a user. Prior to the activation of the device 100, the first shaft 104 will be in a condition so as to traverse freely within the hollow cylindrical shaft 103. The throttle position sensor 108 will sense the fuel supply demand in terms of throttle opening and convey the same to the control unit 109. If the supply demand exceeds a threshold value the control unit 109 activates the actuator 107, causing the second shaft 106 the rotate the hollow cylindrical shaft 103. The rotation of the hollow cylindrical shaft 103 causes the first shaft 104 to traverse within the hollow cylindrical shaft 103, and causes the first shaft 104 and the hollow cylindrical shaft 103 to move close to one-another and in turn reduce the effective length of the input cable. The above mentioned device 100 for controlling speed in a mechanical throttle system can be used in both carburetor and fuel injection systems. Figure 2 illustrates an actuating mechanism for throttle adjustment. The actuator 107 is in communication with the control unit 109 for controlling speed in the mechanical throttle system. In an embodiment the actuator 107 can be a solenoid valve a stepper motor, a pneumatic actuator and a hydraulic actuator. The actuator 107 can have rotary or translator motion. The actuator 107 receives the throttle position Signal from the control unit 109. The actuator 107 converts the signal into corresponding rotary / translator motion of the second shaft 106.

Figure 3 illustrates a method for controlling the mass flow rate of air passing through the intake path of an engine. A position sensor 108 detects 301 the speed of the engine based on the throttle opening. The speed of the engine is compared 302 with the threshold limit for that particular throttle opening. A control unit 109 receives 303 the position of the throttle from a position sensor 108 mounted on a throttle body. An actuator 107 is actuated 304 in response to increase in engine speed above a specified threshold value based on the positional feedback of the throttle conveyed from the position sensor 108 to the control unit 109.ln response to the actuation, a second shaft 106 is rotated 305 to cause rotation of the first shaft 104 that is in geared connection with a hollow cylindrical shaft 103, causing the first shaft 104 to move within the hollow cylindrical shaft 103 for reducing the effective length of the input cable 101 and the second cable 102, and hence control the mass flow rate of air flowing through the throttle body by effectively changing the throttle opening and/ or closing based on the response from the actuator 107. It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

*We Claim:

1. A device (100) for controlling speed in a mechanical throttle system, wherein said device (100) is connected to a first input cable (101) on one side and to a mechanical throttle on the other side by a second cable (102), said device (100) comprising a hollow cylindrical shaft (103) with internal threads (103a) and at least a partially threaded (103b) outer surface forming a pinion; a first shaft (104) with threads (104a) complementary to internal threads (103a) of said hollow cylindrical shaft (103) and positioned coaxially within said hollow cylindrical shaft (103) and adapted to translate to and fro in said hollow cylindrical shaft (103) along a fixed guide (105);
a second shaft (106) with threads (106a) adapted to couple with the pinion formed on the outer surface of said hollow cylindrical shaft (103), and an actuator (107) adapted to drive said second shaft (106), wherein rotation of said second shaft (106) is adapted to cause rotation of said hollow cylindrical shaft (103), and rotation of said hollow cylindrical shaft (103) results in translation of first shaft (104) along said fixed guide (105) within said hollow cylindrical shaft (103) thereby changing the effective length of the cable to open and/ or close the throttle based on the positional feedback of said throttle conveyed from a position sensor (108) to a control unit (109).

2. The device (100) as claimed in claim 1, wherein said actuator (107) is selected from one of a combination of solenoid valve , a stepper motor, a pneumatic actuator and a hydraulic actuator.

3. The device (100) as claimed in claim 1, wherein said device (100) is enclosed within a housing (110).

4. The device (100) as claimed in claim 1, wherein said position sensor (108) mounted on a throttle body.

5. The device (100) as claimed in claim 1, wherein the length of said fixed guide (105) is a function of said throttle opening between maximum and minimum opening position.•

6.wuThe device (100) as claimed in claim 1, wherein said actuator (107) is in communication with said control unit (109) for controlling speed in said mechanical throttle system.

7. A method for controlling the speed in a mechanical throttle system, comprising: detecting the speed of the engine based on the throttle opening by a position sensor (108); comparing said speed with the threshold limit for that particular throttle opening; receiving the position of the throttle by a control unit (109) from a position sensor (108) mounted on a throttle body; actuating an actuator (107) in response to increase in engine speed above a specified threshold value based on the positional feedback of said throttle conveyed from a position sensor (108) to a control unit (109), and rotating a second shaft (106) in response to said actuation of said to cause rotation of first shaft (104) that is in geared connection with a hollow cylindrical shaft (103) for varying the effective length of throttle cable.

8. The method of claim 6, further comprising controlling mass flow rate of air through the intake path of engine based on response from said actuator (107).