DESC:FIELD OF INVENTION
[0001] The present invention relates to a gas (preferably liquefied petroleum gas) fueled vehicle and more particularly to intake system of such a vehicle.
BACKGROUND OF INVENTION
[0002] An LPG vehicle stores the liquefied petroleum gas in a cylinder at high pressure. A LPG feeding system comprises of a reducer that brings down the LPG pressure to a required level from cylinder to the operating range of engine intake. Currently, in the existing vehicles, the engine lacks intake metering of fuel as per engine demand or as per the engine vacuum. Normally, in carburetor engine, the vacuum felt in induction system is used to meter the fuel using different jet and nozzle sizes. Similar induction based feeding system capable of performing similar metering is not applicable in case of LPG. In such a vehicle, if reducer or mixer is calibrated for full throttle requirements, the emissions at lower throttle are increased. On the other hand, if the said reducer or mixer is calibrated for lower throttle requirements, then optimum torque at full throttle is compromised. Hence, there is requirement of an intake system, which can vary the LPG fuel intake inside the engine with varying load as per the requirement.
SUMMARY OF THE INVENTION
[0003] In order to obviate the limitations and the problems associated with the available LPG feeding and metering system, the present invention discloses an intake system for a LPG vehicle. The LPG metering system as described in the present invention comprises of an actuator, which controls the fuel quantity delivered to the engine. The fuel quantity control is based on atleast one input amongst the pressure, TPS (throttle position sensor), temperature and RPM (revolutions per minute) of the engine through an electrical system such as a solenoid valve, stepper motor, servo motor connected to a reducer/mixture body/pipe. The function of the reducer/mixture is to reduce the operating pressure of the LPG. The described mechanism for metering the fuel can be further used for different engine operating modes like power / economy modes. The present invention describes a LPG metering system, which is applicable to four or a two-stroke engine, an air or liquid cooled gasoline engine and single cylindered or multi-cylindered engines that are naturally aspirated or supercharged engines. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle according to present invention comprises of a LPG tank which stores the liquefied petroleum gas at a higher pressure. A reducer is present which alters the fluid pressure in LPG tank to another pre-determined working pressure and is connected to a throttle body of the LPG engine through a pipe. A controller is adapted to receive signals corresponding to intake pressure, intake temperature, exhaust temperature, and throttle position and engine speed signals through corresponding sensors. The controller generates an output signal corresponding to the received signals from the above sensors. The generated output signal is sent from the controller to said actuator which comprises of a means to control the LPG flow to the engine. The means comprises of either of the electrical based systems such as a solenoid valve, stepper motor or a servo motor and is capable of being operated through said generated output signal from said controller. The actuator is connected in-between the reducer and the throttle body and is actuated by the generated output signal to control the fluid flow rate to said throttle body.
BRIEF DESCRIPTION OF DRAWINGS
[0004] Figure 1 illustrates block diagram for intake system of a typical LPG vehicle according to present invention.
[0005] Figure 2 illustrates block diagram for an open loop intake system of a typical LPG vehicle.
[0006] Figure 3 illustrates block diagram for a closed loop intake system of a typical LPG vehicle.
[0007] Figure 4 illustrates a perspective view of the intake system.
[0008] Figure 5 illustrates another perspective view of the intake system showing the actuator system.
DETAILED DESCRIPTION OF THE INVENTION
[0009] In an LPG vehicle, the fuel feeding to intake system of an engine plays a very vital role in balancing the emissions and desired power output. The current invention is applicable to both a two-stroke engine and a four-stroke engine. The four-stroke/ two-stroke engine as per the present invention may further be either of an air-cooled or liquid cooled single cylindered or multi-cylindered gasoline engine. The present invention is further applicable to both the naturally aspirated or supercharged gasoline engines. The present invention is further applicable to a two, three or a four-valve engine, which is either connected or divided. In the most preferred embodiment, while looking at the mounted engine from magneto side, according to one embodiment of the present invention, the fuel intake system according to the present invention is disposed in a horizontal plane of the cylinder head in the front of intake and exhaust ports. According to yet another embodiment of the present invention, while looking at the mounted engine from magneto side, the fuel intake system according to the present invention is disposed in the horizontal plane of the cylinder head at substantially rear of the intake and exhaust ports.
[00010] The proposed actuator, which is an electrically operated valve connected to reducer and provides a mechanism to control fuel flow to meter the LPG fuel supplied to engine. The electrically operated valve gets the signal from controller for its operation. The actuator receives signal from controller based on the signal received by controller from at least one of the pressure sensor, temperature sensor, throttle position sensor or an engine speed sensor. According to yet another embodiment of the present invention, a TCI signal (a different controller unit) actuates the electrically operated valve or actuator instead of the primary controller employed for controlling the actuator. Under fail-safe conditions, if the actuator malfunctions and encounters any operating problem, a TCI generates a dashboard signal and simultaneously bypasses the actuator. Once, actuator is under “bypass”, the flow is directly through the reducer. The disclosed actuator as per the current invention provides a metered quantity of LPG to the engine with input such as ambient pressure, intake pressure, intake temperature, exhaust temperature, throttle position and engine speed, thus improving the fuel efficiency and reducing the exhaust emissions.
[00011] Figure 1 illustrates block diagram for intake system of a typical LPG vehicle. As illustrated in the block diagram, the LPG tank (10) stores the compressed gas at high pressure, which flows to an LPG reducer on demand. Generally, the negative pressure or the vacuum present inside the engine determines the flow rate of the compressed LPG gas from the LPG tank to the LPG reducer. The reducer is calibrated for the full throttle requirement and the zero throttle requirement flow rate of the LPG gas from the reducer to the throttle valve. When the vehicle is running, the desired fuel is fed from the LPG reducer to the engine through the throttle valve body.
[00012] Figure 2 illustrates block diagram for an open loop intake system of a typical LPG vehicle. Here, in this case, the controller TCI (20) communicates with the actuator (reducer electrical unit) and provides the signal for feeding calculated amount of fuel from reducer to the intake manifold. This open loop system does provide the fuel to the engine based on the inputs received from sensors corresponding to the intake pressure, intake temperature, exhaust temperature, TCI and engine speed by controller.
[00013] Figure 3 illustrates block diagram for a closed loop intake system of a typical LPG vehicle. Here, in this case, the controller TCI communicates with the actuator (reducer electrical unit) and provides the signal for feeding calculated amount of fuel from reducer to the intake manifold. The TCI receives the input from plurality of sensors (21) comprising an intake pressure sensor, intake temperature sensor, exhaust temperature sensor, and throttle position sensor and engine speed sensor. As illustrated in the current closed loop block diagram, the feedback of emission parameter is determined using a Lambda sensor. The TCI controller receives feedback signal from lambda sensor to perform corrections in the fuel flow rate through the reducer.
[00014] Figure 4 illustrates a perspective view of the intake system. Figure 4 shows a reducer 41, actuator 42, and throttle body 43, intake port 44, an air filter 45 and data cable 47. The LPG fuel from the reducer 41 is fed to the actuator 42 that is further mounted on the throttle body 43. According to one embodiment of the present invention, the actuator 42 is capable of receiving communication signal from a controller and generates corresponding electrical signals to control the fuel flow by using an electromechanical fluid-flow control device. The actuator 42 is further capable of sensing the signal corresponding to its health to the controller. When actuator is functioning according to the requirements, the actuator sends a “good health” signal to the controller. When actuator is under fault, the actuator sends a “bad health” signal to the controller. The LPG fuel flows through throttle body 43, to the intake port of the engine. The data signal cable 47 transmits the data signal from the TCI (controller) to the actuator 42. The actuator 42 on receiving the data signals from the TCI (controller) through the data cable 47 controls the fluid flow to the throttle body 43. The actuator 42 further comprises of a bypass passage which is used for flow
[00015] Figure 5 illustrates another perspective view of the intake system showing the actuator system. Figure 4 shows the reducer 41, actuator 42, and throttle body 43, intake port 44, the air filter 45 and the data cable 47. The main advantage of using the actuator 42 in between the throttle body 43 and the reducer 41 and using feedback of Lambda sensor to TCI (the controller) is that, the LPG flow from the reducer to the throttle body varies depending on the set point of emission values. The emission values can be set and the controller will function to keep the emission values close to the set point in automatic control mode.
[00016] Moreover, the closed loop involving the feedback from the Lambda sensor for controlling the emissions can function with either one or more than one inputs namely the input of ambient pressure, intake pressure, intake temperature, exhaust temperature, TPS and engine speed. In yet another embodiment of the present invention, the actuator 42 is an electromechanical device, which is capable to process electrical, electronic or digital signal into actuation of a solenoid to vary the cross section of the available flow path and finally to control the LPG flow.
[00017] Hence, the disclosed intake system for a LPG (liquefied petroleum gas) fuelled vehicle comprises of a LPG tank which stores the liquefied petroleum gas at a higher pressure. A reducer (41) is present which alters the fluid pressure in LPG tank to a pre-determined working pressure and is connected to a throttle body (41) of an LPG engine through a pipe. A controller (41) is adapted to receive signals of intake pressure, intake temperature, exhaust temperature, and throttle position and engine speed and to generate a signal corresponding to the received signals. The actuator (42) further comprises of either of the electrical based systems such as a solenoid valve, stepper motor or a servomotor and operates through signal received from the controller.
[00018] The above description describes the present invention in order to enable a personal skilled in the art to appreciate the invention and it’s working. It will be obvious that the invention described above which uses an actuator to control fuel flow rate may be performed in many other possible ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the present invention.
,CLAIMS:We claim:
1. An intake system for a LPG (liquefied petroleum gas) fuelled vehicle comprising:
a LPG tank (10) which stores the liquefied petroleum gas at a higher pressure;
a reducer (41) which alters the fluid pressure in LPG tank (10) to a pre-determined working pressure and is connected to a throttle body (43) of an LPG engine through a pipe (48);
a controller (20) adapted to process a plurality of signals received from plurality of sensors (21), said plurality of signals comprising signals from intake pressure sensor, intake temperature sensor, exhaust temperature sensor, throttle position sensor and engine speed sensor; and
an actuator (42) comprising of at least one electro mechanical device such as a solenoid valve, stepper motor or a servo motor and capable of being operated through signal received from said controller;
characterized in that:
the actuator (42) is disposed in the fuel flow passage in between said reducer (41) and the throttle body (43) where the fuel pressure is substantially lower than the fuel pressure in said LPG tank (10).
2. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1, wherein said actuator (42) is by passed and the fluid flows directly from the reducer (41) to the throttle body (43) through said bypass passage in case of actuator (42) failure.
3. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1, wherein said actuator (42) varies flow area within the fuel flow passage in between said reducer (41) and a throttle body (43) to control fuel flow rate.
4. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1, wherein said actuator is capable of receiving digital signals from controller (20).
5. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1 wherein in said intake system comprises of a bypass passage parallel to said fuel flow passage.
6. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1, wherein said actuator (42) is capable of receiving analog signals from controller (20).
7. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1, wherein said actuator (42) sends health signal to said controller (20); the said health signal comprises of a good health signal and a bad health signal.
8. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1 or claim 6, wherein said actuator (42) is bypassed in case of bad health signal sent to controller (20).
9. The intake system for a LPG (liquefied petroleum gas) fuelled vehicle as claimed in claim 1 or claim 6 or claim 7 wherein during said “bad health” signal from said actuator (42) to said controller (20), the fuel flow passage is from said reducer (41) to said throttle body (43) through said “bypass passage”.