RU2638899C2 - Tank emptying method (versions) - Google Patents

Abstract

FIELD: engine devices and pumps.

SUBSTANCE: invention can be used in fuel feed systems of internal combustion engines (ICE). The method is proposed for emptying a gaseous tank and closing a solenoid tank valve in response to leaks in a fuel line or a fuel distributor for the fuel, including stages at which the fuel tank is emptied by supplying only gaseous fuel to the engine at high pressure in the gaseous fuel tank and feeding gaseous fuel and liquid fuel at low pressure in the tank of gaseous fuel and emptying the tank by closing a valve of the gaseous fuel tank in response to low pressure downstream the valve of gaseous fuel tank and high pressure in the tank.

EFFECT: prevention of fuel loss from gas storage tank when leakage occurs.

8 cl, 7 dwg

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a partial continuation of application for US patent No. 13/431, 295, filed March 27, 2012, the full contents of which are incorporated into the materials of this description by reference for all purposes.

FIELD OF THE INVENTION

The present invention relates to a system and method for closing a valve of a storage tank of a vehicle when leaks in the fuel system are detected. The system and method may be particularly useful for restricting the flow of fuel from tanks that are under pressure.

BACKGROUND

The vehicle may include a pressurized tank that contains fuel or some other gaseous substance that is being used while the vehicle is operating. For example, some vehicles operate using fuel supplied from a pressure tank, while the fuel is stored under pressure, so more fuel can be stored in the tank. Downstream of the tank, a pressure regulator and valves are often included to lower the compressed gas to a more suitable pressure for introduction into the engine, and the compressed gas can be introduced into the engine through pressure lines including a manifold, such as a distribution rail for fuel.

Since the gaseous contents of the storage tank are stored under pressure, a breakthrough of the system into atmospheric pressure can lead to a pressure drop that creates a resulting stream of gaseous fuel from the storage tank to the leakage area. For this reason, vehicles often include leak identification modes to allow the engine to continue to operate when the fuel supply system is subject to a significant leak in the system. One example is shown in US 6,314,948 (publ. 11/13/2001, IPC F02B 47/04, F02D 35/02), which describes a means for detecting pressure in a distributing guide for air to determine if a loss or significant decrease in air pressure has occurred. fed into the distributor guides for fuel and air.

SUMMARY OF THE INVENTION

The authors in the materials of the present description identified the shortcomings of these approaches and proposed a method of closing the tank valve in response to potential leaks in the gas fuel system.

In one aspect, a method for emptying a tank is provided, comprising the steps of:

empty the fuel tank by supplying only gaseous fuel to the engine at high pressure in the gaseous fuel tank and supplying gaseous fuel and liquid fuel at low pressure in the gaseous fuel tank; and

stop emptying by closing the valve of the gaseous fuel tank in response to a low pressure downstream of the valve of the gaseous fuel tank and high pressure in the tank.

In one of the additional options, a method for emptying the tank is proposed, further comprising the step of disabling the fuel nozzle, which is fed with gaseous fuel, when the pressure in the intake manifold of the engine is greater than the ambient pressure, while the termination additionally includes the step where the fuel source is switched.

In a further embodiment, a method for emptying a tank is provided, further comprising the step of disabling the fuel injector, which is supplied with gaseous fuel when the pressure of the gaseous fuel is substantially at ambient pressure.

In one of the additional options, a method is proposed for emptying the tank, in which a fuel nozzle, which is fed with gaseous fuel, injects gaseous fuel into the intake manifold.

In one additional aspect, a method for emptying a tank is proposed, comprising the steps of:

supplying gaseous fuel to the engine from the tank;

carry out the operation of the engine on gaseous fuel and with the first installation of the valve distribution phases in the first state, when the pressure of the gaseous fuel is greater than the first threshold value;

operating the engine on gaseous fuel and with a second setting of valve distribution phases in a first state when the pressure of the gaseous fuel is less than the first threshold value; and

the supply is stopped based on the pressure difference in the gaseous fuel tank and the pressure in the gas rail distributor greater than a threshold value, wherein the pressure in the gaseous fuel tank is greater than the pressure in the gas rail distributor.

In one of the further options, a method for emptying a tank is proposed in which the first state is the rotational speed and engine load, the cessation of which includes closing the valve of the gas fuel tank, wherein the pressure in the gas fuel tank is based on the pressure sensor of the gas fuel tank .

In a further embodiment, a method for emptying a tank is proposed in which the engine inlet valve is opened later relative to the position of the crankshaft when the pressure of the gaseous fuel is less than the first threshold value compared to when the inlet valve is opened when the pressure of the gaseous fuel is greater than first threshold value.

In one of the additional options, a method for emptying the tank is proposed, further comprising the step of injecting gaseous fuel into the engine cylinder at the cylinder inlet stroke when the pressure of the gaseous fuel is less than the first threshold value.

By comparing the pressure in the tank with one or more of the pressure in the fuel rail and the pressure in the fuel line, it is possible to detect leaks in the gas fuel system in some way that provides the ability to accurately identify impairment in the fuel system from the nozzle to the fuel tank still providing increased use of gaseous fuel in the tank even at low pressures. In such a case, the method includes shutting off the supply of gaseous fuel based on too high a pressure in the gaseous fuel tank and insufficient pressure in the gas guide distributor, and closing the valve of the storage tank in response to a detected leak when one or more of the pressure in the guide - the distributor for fuel or pressure in the fuel line drops below the lower threshold value, while the pressure in the tank is higher than the upper threshold value.

In one specific example, based on the differential pressure between the tank and, for example, a high pressure sensor in the fuel line above a threshold value, the method further includes closing the tank valve and switching the fuel source. For example, a vehicle that runs on either gaseous or liquid fuels can switch from operating exclusively on gaseous fuels to operating exclusively on liquid fuels when a leak develops in a gas fuel system. If the engine were to continue operating while gaseous fuel was supplied from the storage tank, the engine could run on a leaner mixture than required, as there could be insufficient fuel consumption from the tank to the engine.

The present description may provide several advantages. In particular, the approach may be applicable to various types of fuel injection systems and gases. In addition, the present description provides an operating mode based on the stored amount of fuel in order to reduce fuel loss. Therefore, the approach can reduce the amount of gaseous fuel that can be released into the atmosphere if a leak develops in the gas fuel system. In addition, when no leaks are detected, the engine system functions as intended, and the system additionally provides the ability to: supply exclusively gaseous fuel to the engine when the pressure of the gaseous fuel is greater than the threshold pressure in the tank; and supplying gaseous fuel and liquid fuel when the pressure of the gaseous fuel is less than the threshold pressure in the tank. By supplying liquid fuel and gaseous fuel to the engine when the pressure in the tank is less than the threshold pressure in the tank, it may be possible to draw additional gas from the storage tank along with the delivery of liquid fuel to the engine, so that the engine does not pass ignition and does not operate richer blends than required. Thus, the gaseous fuel tank can be freed from the compressed gas while the engine provides acceptable performance in some way, which lengthens the working time or range of the vehicle and the engine, since the gas tank can be completely freed from the contents.

The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description when taken individually or in connection with the accompanying drawings. It should be understood that the disclosure of the invention above is presented to familiarize yourself with a simplified form of a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that accompany the detailed description. Moreover, the claimed subject matter is not limited to the options for implementation, which exclude any disadvantages noted above or in any part of this description.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages described in the materials of the present description will be more fully understood after reading the example of an embodiment indicated in the materials of the present description as a description of preferred embodiments of the invention, when taken individually or with reference to the drawings, in which:

FIG. 1 is a schematic illustration of an engine;

FIG. 2 is a schematic illustration of a dual-fuel fuel supply system capable of selectively supplying gaseous and liquid fuels to an engine;

FIG. 3 is a flowchart of an example method illustrating how a controller controls both engine and fuel supply systems;

FIG. 4 is a flowchart of an exemplary method of closing a tank valve in response to a leak in a gaseous fuel supply system;

FIG. 5 and 6 show simulated operating sequences according to the method of FIG. 7;

FIG. 7 is a flowchart of an example method for emptying a pressurized tank on board a vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The present description relates to a method for closing a tank valve in response to a leak in a dual-fuel fuel supply system that encloses compressed gas on board a vehicle. In one non-limiting example, the tank may be filled with fuel, such as compressed natural gas, as illustrated in FIG. 1. FIG. 2 then shows a fuel storage tank with a pressure sensor attached thereto, the location of which within the fuel system makes it possible to detect leaks in the manner described herein. In FIG. 3, the engine system further includes a controller capable of both controlling engine operations and diagnostic procedures according to a method which, as shown in FIG. 4 includes leak detection within the fuel supply system based on pressure measurements and closing the tank valve when a leak is detected. When no leakage is detected, the fuel system functions as intended and the tank can be emptied as described in the simulated sequences provided in FIG. 5 and 6. In one example, the engine can be driven to enhance the extraction of fuel vapor from the tank, therefore, the tank can be emptied more completely. The method of FIG. 7, therefore, provides improved pumping of tanks in engines with direct fuel injection, as well as in engines with fuel injection into the inlet channel.

With reference to FIG. 1, an internal combustion engine 10 comprising a plurality of cylinders, one cylinder of which is shown in FIG. 1 is controlled by an electronic motor controller 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32 with a piston 36 located therein and connected to the crankshaft 40. The combustion chamber 30 is shown in communication with the intake manifold 44 and exhaust manifold 48 through a corresponding intake valve 52 and exhaust valve 54. Each the intake valve and the exhaust valve may be actuated by the intake valve cam 51 and the exhaust valve cam 53. Alternatively, one or more of the inlet and outlet valves may be actuated by an electromechanically controlled valve coil and armature assembly. The position of the intake valve cam 51 may be detected by the intake valve cam sensor 55. The position of the exhaust cam 53 may be detected by the exhaust cam cam sensor 57.

A direct injection liquid fuel nozzle 66 is shown disposed to inject liquid fuel directly into the combustion chamber 30, which is known to those skilled in the art as direct injection. Alternatively, liquid fuel may be injected into the inlet, which is known to those skilled in the art as injection into the inlet. The direct injection liquid fuel nozzle 66 supplies liquid fuel proportionally to the pulse width from the controller 12. The fuel nozzle 66 receives the liquid fuel through the fuel distributor rail 67, which is supplied by the liquid fuel supply system 230, which includes a fuel tank, a fuel pump and a guide- distributor for fuel.

A direct injection gaseous fuel nozzle 80 is shown disposed to inject gaseous fuel directly into the combustion chamber 30. The direct injection gaseous fuel nozzle 80 may be configured to supply liquid or gaseous fuel. An inlet gas injector 81 for injecting gaseous fuel into an inlet manifold 44. In some examples, an inlet gas nozzle 81 for injecting gas into an inlet may be located at an inlet of a cylinder head. In other examples, the gaseous fuel injector 81 may inject gaseous fuel into the central zone of the intake manifold. Both the direct injection gaseous fuel nozzle 80 and the injection gaseous fuel nozzle 81 can supply gaseous fuel to the engine 10. However, the gaseous fuel can be supplied exclusively through the direct injection gaseous fuel nozzle 80 without injecting the gaseous fuel nozzle 81 into the inlet to other examples. Additionally, gaseous fuel can be supplied exclusively through the gaseous fuel injector 81 to the inlet channel without the direct injection gaseous fuel nozzle 80, in addition to other examples. In general, dual-fuel fuel delivery systems are configured such that liquid fuel is injected directly into the combustion chamber 30 while the gaseous fuel is injected into the inlet channel to the intake manifold 44.

The direct injection gaseous fuel nozzle 80 and the gaseous fuel injection nozzle 81 into the inlet accepts gaseous fuel through the fuel rail 90 and the fuel tank 91. The pressure regulator 86 controls the pressure supplied to the fuel rail 90 with the fuel tank 91. Gas pressure in the fuel tank 91 is read by a pressure sensor 60. The gas pressure in the fuel rail 90 is read by a pressure sensor 61. The direct injection gaseous fuel nozzle 80 and the inlet gas nozzle 81 can be controlled independently by the controller 12, so that each produces a different flow rate at different times.

The intake manifold 44 is shown in communication with a possible electronic throttle 62, which adjusts the position of the throttle valve 64 to control the flow of air from the air intake 42 to the intake manifold 44. The electronic throttle 62 is shown located between the intake manifold 44 and the air intake 42.

An ignition system 88 without a distributor delivers an ignition spark to the combustion chamber 30 through the spark plug 92 in response to the action of the controller 12. A universal exhaust oxygen sensor (UEGO) 126 is shown connected to the exhaust manifold 48 upstream of the catalytic converter 70. Alternatively, a dual-mode exhaust oxygen sensor may be used in place of the UEGO sensor 126.

The catalytic converter 70 of the exhaust gas may include multiple converter units in one example. In yet another example, multiple exhaust emission reduction devices, each with multiple briquettes, may be used. The catalytic converter 70 of the exhaust gases, in one example, may be a three-way catalytic converter.

Controller 12 is shown in FIG. 1 as a conventional microcomputer, including: a microprocessor unit 102, input / output ports 104, read-only memory 106, random access memory 108, non-volatile memory 110, and a traditional data bus. The controller 12 is shown receiving various signals from sensors connected to the engine 10, in addition to those signals discussed previously, including: engine coolant temperature (ECT) from a temperature sensor 112 connected to the cooling pipe 114; a position sensor 134 connected to the accelerator pedal 130 for sensing a force exerted by the foot 132; measuring the pressure in the intake manifold of the engine (MAP) from a pressure sensor 122 connected to the intake manifold 44; an engine position sensor from a Hall effect sensor 118 sensing the position of the crankshaft 40; measuring the mass of air entering the engine from the sensor 120; and measuring the position of the throttle from the sensor 58. Barometric pressure can also be read (sensor not shown) for processing by the controller 12. In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of evenly spaced pulses every revolution of the crankshaft from which rotation speed can be determined engine (RPM in revolutions per minute).

In some embodiments, the engine may be coupled to an electric motor / battery system in a hybrid vehicle. A hybrid vehicle may have a parallel configuration, a serial configuration, or variants or combinations thereof. In addition, in some embodiments, other engine configurations, such as a diesel engine, may be used.

During operation, each cylinder in the engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, typically, the exhaust valve 54 closes and the intake valve 52 opens. Air is drawn into the combustion chamber 30 through the intake manifold 44, the piston 36 moves to the bottom of the cylinder to increase the volume inside the combustion chamber 30. The position in which the piston 36 is near the bottom of the cylinder and at the end of its stroke (for example, when the combustion chamber 30 is at its largest volume) is typically referred to by those skilled in the art as a lower dead point (BDC). At the compression stroke, inlet valve 52 and exhaust valve 54 are closed. The piston 36 moves to the cylinder head to compress air inside the combustion chamber 30. The point at which the piston 36 is at the end of its stroke and closest to the cylinder head (for example, when the combustion chamber 30 is at its smallest volume) is typically indicated by those skilled in the art as top dead center (TDC). In the process, hereinafter referred to as injection, fuel is introduced into the combustion chamber. In the process, hereinafter referred to as ignition, the injected fuel is ignited by a known ignition means, such as spark plug 92, resulting in combustion. At the expansion stroke, expanding gases push the piston 36 back into the BDC. The crankshaft 40 converts the movement of the piston into the torque of the rotating shaft. Finally, at the exhaust stroke, the exhaust valve 54 opens to discharge the combusted air-fuel mixture to the exhaust manifold 48, and the piston returns to the TDC. Note that the above is merely shown as an example, and that the settings for opening and / or closing the inlet and outlet valves can be changed so as to give positive or negative valve closure, late closing of the inlet valve, or various other examples.

FIG. 2 shows an exemplary embodiment of a dual fuel fuel supply system capable of selectively supplying both gaseous fuel and liquid fuel through dual or multiple fuel rail distributors to a plurality of fuel nozzles of an internal combustion engine. Although dual fuel rail distributors are shown in an exemplary fuel supply system, in some examples, a dual fuel fuel supply system may have a single fuel rail distribution to supply both gas and liquid fuels. The fuel supply system 200 comprises a gaseous fuel supply system 202, a liquid fuel supply system 230, and fuel distribution rails 67 and 90. The fuel distribution rail 90 connects the gaseous fuel supply system 202 to the nozzles 81, and the fuel distribution rail 67 connects the liquid fuel supply system 230 to the nozzles 66, where, as a non-limiting example, the nozzles 66 and 81 can supply fuel to different cylinders engine 10.

The gaseous fuel supply system 202 includes a gaseous fuel source, which, in an exemplary embodiment, is compressed natural gas (CNG). However, the fuel source is non-limiting, and a different fuel source may be used. Gaseous fuel supply system 202 includes a gaseous fuel tank 91 and a flow limiting valve 210 (EFV). The gaseous fuel tank 91 may be a pressurized gaseous fuel tank containing high pressure gaseous fuel, where the "high pressure" is a pressure higher than the pressure of the liquid fuel, while it enters the fuel distribution rail 90 . The pressure sensor 60 may measure the pressure inside the gaseous fuel tank 91 and transmit data to an electronic control unit 250 (ECU), which may be a controller 12. In some embodiments, the pressure sensor 60 may be located near the fuel tank 91, while in other embodiments, it may be coupled to a fuel tank. The pressure sensor 60 may further be connected to an opening 205, which is an opening that limits leakage if the pressure sensor is removed, for example, when the sensor is replaced. In some embodiments, the pressure in the fuel tank may be logically outputted to a pressure sensor in the high-pressure line, for example, pressure sensor 224, within the gaseous fuel supply system 202.

A flow restriction valve 210 is connected to the gaseous fuel tank 91 by a fuel supply line 215, which is a high pressure fuel supply line. A pressure sensor 224 is connected to the fuel supply line 215 and measures the gas pressure inside the high pressure fuel supply line. A pressure regulator 86 downstream of the fuel tank 91 controls the pressure supplied to the fuel rail 90. Downstream of the pressure regulator 86 is a fuel supply line 216, which may be a low pressure fuel line that couples the high pressure fuel supply line 215 to the fuel rail 90. Therefore, the pressure regulator 86 separates the channel into a high pressure region and a low pressure region. In some embodiments, the pressure regulator 86 may include a solenoid-controlled opening / closing solenoid valve at any of the inlet or outlet of the pressure regulator 86. Compared to the high pressure fuel supply line 215, the fuel supply line 216 is a low pressure line, however, the gas pressure in the fuel supply line 216 can sometimes be relatively high, for example, after the pressure regulator 86 supplies gas from the fuel tank 91 to low pressure supply line. Then, once gas in the fuel supply line 216 has been injected into the engine 10, the pressure in the fuel supply line 216 can again return to a relatively low value compared to the pressure in the fuel supply line 215. Thus, the pressure in the fuel supply line 216 can continuously reciprocate as fuel from the fuel tank 91 is injected into the engine 10. A coalescing filter 220 is disposed within the fuel supply line 216, which acts to clean the gaseous fuel by fragmentation filtering particles and oil mist as the gaseous fuel stream reaches the fuel line from the fuel tank 91.

The flow limiting valve 210 controls the flow of gaseous fuel from the gaseous fuel tank 91 and is connected to the ECU 250. The flow limiting valve 210 may include a self-driving mechanical EFV 222, which can automatically return to its original state as soon as the leak is eliminated. However, since the flow restriction valve 210 also has a bypass outlet 229 located in line 219, a small leakage stream may be present when it is subjected to a change in position. Essentially, a mechanical EFV can weaken the flow of fuel from the tank rather than completely isolate it. As soon as the leak is eliminated, the leak flow through the outlet 229 slowly re-increases the pressure of the downstream volume, and therefore, automatically returns the EFV to its original state. The ability to automatically return to original state makes EFV one of the self-returning types. In order for the line to undergo a repeated increase in pressure, a sufficient amount of gas must be present in the tank to feed the fuel line.

The tank valve assembly may further include an electronic solenoid valve 212, which is included and completely shuts off the gas flow. A flow restriction valve shuts off the fuel flow from the tank if the flow exceeds a threshold value indicating the maximum allowable flow of fuel into the engine. Since the electronic solenoid valve 212 is a mechanical device, it has a single adjustment that is set to change the position when the fuel flow to the engine is above the upper allowable fuel consumption of the engine. In some embodiments, the tank valve assembly may also include a shut-off valve 214, which allows refueling when the solenoid valve 212 is closed. In yet another exemplary embodiment, the flow limiting valve 210 may not include a shut-off valve and be solenoid a valve 212 controlled by ECU 250. In yet another embodiment (not shown), the gaseous fuel supply system 202 may be powered by various gaseous fuel sources, such as source of evaporated liquid fuel.

The gaseous fuel supply system 202 comprises a filling inlet 228 that allows the fuel tank 91 to refuel with fuel through the fuel line 217. Two redundant one-way shut-off valves 226 are also included in the fuel line 217 to prevent the flow of gaseous fuel from the fuel supply line 215 to the atmosphere outside the gas fuel system. Redundancy is included in order to isolate the gaseous fluid in the event that the shutoff valve is kept open, for example, being stuck in the open position. Gaseous fuel is added at the filler inlet 228 and flows through the fuel line 217 to the fuel supply line 215, and also through the fuel line 218, where the one-way shut-off valve 214 is oriented in some way that allows flow from the filler inlet 228 to the tank 91 gaseous fuel and prevents the flow of gaseous fuel from the tank 91.

Further, referring to the liquid fuel system, the liquid fuel supply system 230 includes a liquid fuel source, a valve 232, a shutoff valve 235, and a pressure relief valve 236. In an exemplary embodiment, the liquid fuel source includes a liquid fuel tank 240 filled with liquid fuel 244, a fuel level sensor 246, and a fuel pump 248. The liquid fuel 244 may be drawn into the fuel pump 248 from the inlet 234 and pumped into the supply line 237. The fuel pump 248 is controlled by the ECU 250. An optional high pressure pump controlled by the ECU 250 can be inserted downstream of the fuel pump 248 to increase the pressure of the liquid fuel entering the fuel distribution rail 67. The fuel level sensor 246 may be a liquid level sensor that can detect the storage volume in the fuel tank 240 and transmit the storage volume to the ECU 250. The liquid fuel tank 240 may also include a ventilation duct to allow air or fuel vapor to flow under atmospheric pressure into and from the tank.

A one-way shut-off valve 235 is present between the liquid fuel source and the valve 232 to prevent the liquid fuel from flowing back to the liquid fuel source when the liquid fuel is supplied to the fuel distribution rail 67. A pressure relief valve 236 connected between the liquid fuel source and the valve 232 provides a return path for liquid fuel displaced from the fuel distribution rail 67. When the return path of the pressure relief valve 236 is directed back to the pump inlet, as shown in FIG. 2, pressure may be relieved when fuel pump 248 is turned off or operating at partial voltage / speed / pressure. However, in some embodiments, the return path of the pressure relief valve 236 may return to the inside of the tank indicated by the liquid fuel 244. In this configuration, the pressure relief valve 236 may be associated with the inlet pressure of the solenoid valve 232. The threshold value for the valve to open 236 pressure relief, may be greater than the pressure generated by the source of liquid fuel, and less than the minimum pressure for gas injection. The pressure relief valve 236 closes when the liquid fuel flows from the liquid fuel source to the fuel distribution rail 67. In an exemplary embodiment, valve 232 comprises a float valve. The float valve contains a ball that floats in liquid fuel, but drowns in gaseous fuel. When the ball in the float valve sinks, it blocks the path through the valve, and the valve closes. Liquid fuel can flow through the float valve, but gaseous fuel cannot flow through the float valve. In other embodiments, valve 232 may be a solenoid valve controlled by ECU 250. In yet another embodiment, valve 232 may be combined into a single valve supplying a fuel rail. In yet another embodiment, valve 232 may be a shutoff valve, a fuel oil reservoir may be coupled to the fuel rail 67, and pressure relief valve 236 may be omitted.

In FIG. 2, the fuel supply system 200 comprises a fuel distribution guide 67 for liquid fuel inlet from the supply line 239 and a fuel distribution rail 90 for fuel gas inlet from the fuel supply line 216, and a pressure sensor 61 for transmitting pressure of the distribution rail for fuel in the ECU 250. The fuel distribution rails are often tubular and thus, depending on the inclination of the vehicle, the fuel distribution rail should preferably have a drain zhny channel at each end to allow the discharge of liquid fuel from the guide-distributor for fuel. A fuel supply line 216 connects the outlet of the gaseous fuel supply system 202 to the fuel rail 90. Fuel nozzles 81 are mounted on top of the fuel rail 90 so that the fuel nozzle inlets are at least partially facing the surface. In some embodiments, fuel nozzles mounted above the fuel rail may primarily use gas (or vapor) fuel, while fuel nozzles mounted below the fuel rail may primarily use liquid fuel.

When fuel injectors 66 are liquid fuel injectors, fuel pump 248 and a possible high pressure pump are turned on, valve 232 is open, and pressure relief valve 236 and flow restriction valve 210 are closed. Liquid fuel flows from the liquid fuel tank 240 to the inlet 234 and through the supply lines 237 and 239 to the fuel distribution rail 67. The fuel distribution rail 67 is filled with liquid fuel under pressure, which can be injected by the fuel nozzle 66 in proportion to the pulse width of the FPW-2 signal received from the controller 12.

When fuel injectors 81 inject gaseous fuel, fuel pump 248 and a possible high pressure pump can be turned off, valve 232 is closed and flow restriction valve 210 is open. Gaseous fuel flows from the gaseous fuel tank 91 through the fuel supply lines 215 and 216 to the fuel rail 90. The fuel distribution rail 90 is filled with compressed gaseous fuel, which can be injected by the fuel nozzle 81 in proportion to the pulse width of the FPW-2 signal received from the controller 12.

In order to switch from liquid fuel to gaseous fuel, the fuel pump 248 and a possible fuel pump are taken out of operation, and the flow restriction valve 210 is opened. In some embodiments, where a single fuel rail is used to inject both types of fuel, during the transition, the fuel rail may contain gaseous fuel and liquid fuel at the same time. High pressure gaseous fuel flows into and rises to the top of the fuel rail. The position and orientation of the nozzles in the upper part of the fuel distributor rail accelerates the transition from liquid fuel to gaseous fuel, since gaseous fuel rising upward is preferably supplied to the nozzles. Injection of gaseous fuel with a fuel nozzle may begin even before the fuel rail is completely free of liquid fuel. The use of high pressure gaseous fuel forces liquid fuel to flow from the fuel distributor rail back to the liquid fuel tank 240 through a path including a pressure relief valve 236. The transition ends when the gaseous fuel reaches the float valve 232. The float valve 232 sinks when it is exposed to liquid fuel drain, protecting the gaseous fuel from entering the liquid fuel supply system 230.

On the contrary, the transition from gaseous fuel to liquid fuel in an exemplary system having a single fuel distributor guide, the flow restriction valve 210 is closed, and the fuel pump 248 and a possible fuel pump are turned on. The remaining gaseous fuel in the fuel rail is fed into the nozzles as the liquid fuel flows into the fuel rail. Gaseous fuel is quickly removed from the fuel distribution rail, since the fuel distribution rail holds a small mass of gaseous fuel compared to liquid fuel.

The various components described above with reference to FIG. 2 can be controlled by an ECU 250, which includes a controller 12 with computer readable instructions for performing procedures and procedures for regulating a vehicle system, a plurality of sensors 252, and a plurality of actuators 254.

FIG. 3 is a flowchart of an example method 300 illustrating how a controller 12 can monitor sensors (eg, pressure sensor 60) and read diagnostic codes within the system to determine the amount and types of fuel supplied to the engine system 10. At 302, method 300 includes monitoring sensors within the fuel supply system 200. For example, the pressure sensor 60 may measure the pressure inside the gaseous fuel tank 91 while the pressure sensor 224 measures the pressure inside the high pressure fuel supply line 215. Each of these sensors, in this case, can transmit data to the controller 12, which can additionally use information to determine if a leak exists in the high-pressure supply line. If a leak is detected, the controller 12 may set a diagnostic code indicating the leak and store the code status in memory to inform the passenger of the vehicle. If a leak is detected at step 302, the gaseous fuel supply system 202 may continue to operate as intended, and the method 300 proceeds to step 304.

At 304, method 300 includes using a controller 12 to determine engine operating conditions. Then, based on the conditions identified, the controller 12 may supply gaseous or liquid fuel, or a combination thereof, to the fuel rail to feed the engine 10. For example, a high pressure engine in the intake manifold may indicate that the engine is operating at high load engine. To provide engine load, the controller 12 can adjust the amount of gaseous fuel injected into the intake manifold or the inlet of the engine cylinder in response to pressure in the engine intake manifold, thereby generating the desired engine torque. After adjusting engine operation, method 300 may continue to monitor the engine system and make further adjustments in response to sensors within the engine system.

FIG. 4 shows a flowchart of an example method 400 that closes a tank valve in response to leaks detected in a gaseous fuel supply system. For example, a fuel line leak may result in a circuit of a vehicle’s high pressure piping being burst at atmospheric pressure. As a result, fuel consumption from the storage tank can be enhanced since gaseous fuel stored under higher pressure flows into the leakage region having lower pressure. Although, in the presence of a leak, a certain amount of gaseous fuel can still be distributed among the engine nozzles, some of the gaseous fuel can be removed from the fuel system. Therefore, fuel supply systems often become equipped with a flow restriction valve that closes to attenuate the flow of fugitive gas when a leak is present. For this reason, the flow valve described herein includes an electronic solenoid valve connected to a mechanical flow restriction valve to restrict fuel flow when a leak is detected in a gas fuel system.

At step 402, a leak develops in the gas fuel system, which causes a pressure drop. In response to a pressure drop, gaseous fuel may flow from the fuel tank and thereby reduce the mass of stored fuel contents. For example, the fuel inlet may be stuck in the open position, causing the fuel to flow out of the system if the EFV does not change position to restrict the flow of fuel from the tank. In response to a leak in the system, method 400 includes monitoring sensors within the fuel supply system. For example, controller 12 may receive data from a pressure sensor 61 inside a fuel rail or pressure sensor 60 located near a storage tank. Based on the received data, the controller 12, which includes a microprocessor unit and various memory units, can be programmed to make adjustments based on a leak in the fuel supply system.

At step 404, method 400 includes measuring a fuel flow rate from a tank and comparing the measured flow rate with a threshold flow rate selected to indicate possible leaks in the system. For example, a leak in the low pressure fuel supply line 216 may cause the pressure measured by the pressure sensor 61 to decrease. This pressure drop may cause the fuel nozzles 81 to remain open longer, which, in turn, may cause the pressure regulator 86 to respond by increasing the flow of fuel from the tank to raise the pressure of the fuel supplied to the nozzles.

At 406, fuel consumption above a threshold causes the flow restriction valve to slam shut, which limits fuel flow from the fuel tank. Then, at step 408, the controller 12 can switch the fuel source to liquid fuel in response to a drop in injection pressure, which results in a limited flow of gaseous fuel. If the mechanical EFV is self-driving, which means that it can automatically return to its original state as soon as the leak is repaired, the valve can still have a small leak flow when it changes position. Essentially, a mechanical EFV can significantly attenuate fuel flow from a tank, rather than completely isolating it. Therefore, to ensure that fuel is no longer lost from the storage tank, at step 410, the tank valve and / or regulator valve is closed by the controller 12. Returning to step 404, if the measured fuel flow from the tank is below the threshold flow, the controller 12 can determine that the fuel supply system is working as intended, and to continue monitoring sensors within the fuel system.

To confirm the presence of a leak in the gas fuel system, method 400 additionally uses pressure data from sensors in the system to diagnose a leak. Therefore, in step 412, method 400 includes comparing the pressure in the high pressure fuel supply line (P _HPL ) with the gas pressure in the tank (P _Tank ) to determine if a leak has developed in the high pressure fuel supply line. For example, if an orifice is blown in a high-pressure fuel line, such as a fuel supply line 215, then the pressure measured downstream of the tank may decrease as some gas escapes from the fuel supply system. Essentially, the pressure measured by the pressure sensor 224 in the fuel line can be significantly lower than the pressure of the tank measured by the pressure sensor 60. If the pressure P _HPL in the fuel line remains below the first lower threshold value while the pressure P _Tank in the tank is above the upper threshold value, so that the difference between P _HPL and P _{Tank is} greater than the first threshold value of the difference, at step 414, the method identifies a leak in the fuel supply line and sets a diagnostic code to indicate a leak in 418. When the leak is confirmed in the gas fuel system, the tank valve and the solenoid valve can remain closed until the vehicle is about to deserves, or, in some cases, the vehicle is not subject to re-ignition is switched on.

Returning to step 412, if the P _HPL is substantially equal to the P _Tank , the method continues to monitor pressure data from the fuel rail to determine if there is a leak in the system. Essentially, at step 420, method 400 includes comparing the pressure in the low pressure fuel line (P _LPL ) with adjustable fuel pressure control (P _Regulator ). For example, if the difference between the pressure P _LPL in the low pressure fuel line and the regulated pressure P _{Regulator is} greater than the second difference threshold value, a leak in the system is confirmed. Moreover, if the P _LPL is lower than the P _Regulator , the leak can be isolated by the low pressure fuel line, for example, in the fuel supply line 216 or the fuel rail 90. However, if the P _{LPL is} larger than the P _Regulator , a leak may exist in the high pressure region. In one example, if the diaphragm of the pressure regulator breaks, the pressure in the fuel rail can increase as the gas content flows into the fuel rail, which can also cause damage to the nozzles in some cases. Therefore, method 400 can also be used to reduce damage within the fuel system. If the difference between the pressure P _LPL in the fuel line and P _Regulator remains, at step 414, the method identifies a leak in the fuel supply line and sets a diagnostic code to indicate the leak at step 418. In the same manner as described above with reference to block 412, when the leak is confirmed in the gas fuel system, the tank valve and the solenoid valve can remain closed until the vehicle is serviced or undergoes a new ignition switch.

At 420, if P _HPL and P _LPL are substantially equal to P _Tank and P _Regulator, respectively, then method 400 may continue to operate as intended, even if the EFV was subjected to a change of position. Method 400 offers advantages for the reason that the leak detection system can automatically reset if the EFV changes position when the leak is virtually absent in the system.

Referring to a method of emptying a pressurized fuel tank on board a vehicle to help empty the tank, the controller 12 may include instructions to ignore the various safety features described that close the tank valve in response to a leak. Essentially, when the actual or inertial pressure in the tank is below the threshold pressure in the tank, the contents of the tank can still be emptied by the methods below. However, in order to bleed the tank to dryness, the pressure in the fuel rail can sometimes fall below the regulated pressure, which is a problem for method 400, which can interpret the low pressure in the fuel rail as a leak that gives rise to the valve was closing. Therefore, in order to empty the contents of the tank, the controller 12 may also be able to ignore the leak detection system and keep the tank valve open, thereby allowing the contents of the tanks to empty in the manner described.

FIG. 5 shows a simulated operating sequence according to the method of FIG. 7, when the engine has gaseous fuel injectors injected into the inlet channel without direct injection gaseous fuel nozzles. The sequence of FIG. 5 may be provided by the system of FIG. 1 according to the method of FIG. 7. Vertical labels are shown at times T ₀ -T ₅ to identify specific points of interest of interest during the sequence.

The first graph from above in FIG. 5 represents the pressure in the intake manifold of the engine versus time. The Y axis represents the pressure in the intake manifold of the engine, and the pressure in the intake manifold rises in the direction of the arrow of the Y axis. The X axis represents time, and the time increases on the left side of FIG. 5 to the right side of FIG. 5. The horizontal mark 502 represents the ambient air pressure. The pressure above the ambient pressure is above the horizontal mark 502. The pressure below the ambient pressure is below the horizontal mark 502.

The second graph from above in FIG. 5 represents the amount of liquid fuel injection versus time. The Y axis represents the amount of liquid fuel injected into the engine, and the amount of injected liquid fuel increases in the direction of the arrow of the Y axis. The X axis represents time, and the time increases on the left side of FIG. 5 to the right side of FIG. 5.

The third graph from above in FIG. 5 represents the amount of gaseous fuel injection injected into the engine through the gaseous fuel nozzle of the injection into the inlet, versus time. The Y axis represents the amount of gaseous fuel injected through the hole or central nozzle. The amount of gaseous fuel injected into the engine increases in the direction of the arrow of the Y axis. The X axis represents time, and the time increases on the left side of FIG. 5 to the right side of FIG. 5.

The fourth graph from above in FIG. 5 represents the state of disabling the injection of a gaseous fuel injector into the inlet channel, and whether or not the injection of the gaseous fuel injection nozzle from the operation is taken out of operation. The Y axis represents the operating state of the gaseous fuel injector injection into the inlet channel. The inlet of the gaseous fuel injection into the inlet channel is valid when the signal is at a low level. The gaseous fuel injector injects into the inlet channel out of operation when the signal is at the upper level. The X axis represents time, and time increases on the left side of FIG. 5 to the right side of FIG. 5.

The fifth graph from above in FIG. 5 represents the pressure in the distribution rail / storage tank for gaseous fuels versus time. The Y axis represents the fuel pressure within the fuel pressure in the gaseous fuel storage tank, and the fuel pressure increases in the direction of the arrow of the Y axis. The X axis represents time, and the time increases on the left side of FIG. 5 to the right side of FIG. 5. The horizontal mark 504 represents the threshold pressure in the tank, where the liquid fuel injection is actuated to provide the required combustion in the engine. In one example, the horizontal mark 504 represents the pressure of the fuel, where less than the required amount of gaseous fuel flows into the engine than is required to provide the required level of engine torque. The gaseous fuel pressure is at ambient pressure when the gaseous fuel pressure reaches the X axis.

At time T ₀ , the pressure in the intake manifold of the engine is relatively low, indicating a low engine load. The amount of liquid fuel injection is essentially zero, and the engine is driven exclusively by gaseous fuel, although, earlier in time, the engine could be operated on liquid fuel (for example, during engine start). The gaseous fuel nozzle is driven as indicated by the state of withdrawal of the gaseous fuel nozzle from operation. The amount of gaseous fuel stored in the gaseous fuel tank is at a higher level.

Between time T ₀ and time T ₁ , the pressure in the intake manifold of the engine rises, indicating that the engine is operating at a higher engine load. The amount of gaseous fuel injected into the engine intake manifold or cylinder inlet increases as the pressure in the engine intake manifold rises so that the required engine torque can be output. The gaseous fuel injector injection into the inlet channel remains active, and the pressure in the gaseous fuel tank decreases as the gaseous fuel is consumed by the engine.

At time T ₁ , the pressure in the intake manifold reaches a higher pressure, where the gaseous fuel nozzle is taken out of operation. The gaseous fuel nozzle can be taken out of operation, so that the engine power output can be further increased when additional air is allowed to flow into the engine to be combined with liquid fuel. Additional air flows into the engine when the gaseous fuel injector injects into the intake channel or central injection is taken out of operation, since the volume in the intake manifold is not displaced by the gaseous fuel. Thus, the amount of injected liquid fuel increases between the time T ₁ and the time T ₂ in order to increase the engine power output to meet the desired engine torque. The gaseous fuel nozzle is active, and is not in a deactivated state when the pressure in the intake manifold of the engine rises. The pressure in the gaseous fuel tank continues to decrease as gaseous fuel is consumed. In some cases, when the engine output is high, a combination of liquid and gaseous fuels can be supplied to produce the required engine torque.

At time T ₂ , the pressure in the intake manifold of the engine decreases to a level where the return of the gaseous fuel nozzle increases, and where the liquid fuel nozzle is taken out of operation. The gaseous fuel nozzle remains active, and the pressure in the gaseous fuel tank continues to decrease as gaseous fuel is consumed.

Between time T ₂ and time T ₃ , the pressure in the intake manifold rises and falls depending on the engine load. Engine load may increase or decrease in response to the torque required by the driver. The gaseous fuel nozzle remains active and gaseous fuel is injected into the engine. The amount of gaseous fuel stored in the gaseous fuel storage tank continues to decrease as gaseous fuel is consumed by the engine.

At time T ₃ , the pressure of the gaseous fuel stored in the gaseous fuel tank decreases to a level lower than the predetermined threshold pressure in the tank indicated by a horizontal mark 504 (e.g., 250 psi). At a pressure below the threshold pressure indicated by the horizontal mark 504, less than the required amount, fuel can flow out of the gaseous fuel storage tank into the engine. The threshold pressure in the fuel tank indicated by a horizontal mark 504 may vary for different operating conditions. For example, the threshold pressure in the tank, indicated by a horizontal mark 504, may increase as the pressure in the intake manifold of the engine increases. Conversely, in some examples, when the pressure in the gaseous fuel tank decreases below the threshold pressure in the tank indicated by the horizontal mark 504, the pressure in the fuel rail may also drop in response to the reduced pressure in the tank. For example, when gaseous fuel is the only fuel source, the pressure drop in the fuel rail is obtained from the pressure drop in the tank, since the pressure in the tank also corresponds to the pressure in the high-pressure fuel line and the injection pressure.

The nozzle of the gaseous fuel injection into the inlet or central injection remains active, and the gaseous fuel continues to flow into the engine at time T ₃ . However, the amount of gaseous fuel supplied to the engine is supplemented by the injection of liquid fuel into the engine. Thus, the liquid fuel nozzle is driven to supply fuel to the engine cylinder. Thus, combustion stability and air-fuel ratio control can be adjusted to the required levels. Additionally, as the pressure in the intake manifold increases with increasing engine load, a smaller amount of gaseous fuel is able to be introduced into the intake manifold of the engine. Therefore, the amount of liquid fuel as a percentage of both types of fuel entering the engine rises as the pressure in the intake manifold increases. While the pressure in the intake manifold decreases with engine load, more gaseous fuel can be introduced into the engine, and the percentage of liquid fuel injected into the engine is substantially reduced. The oxygen sensor in the engine exhaust system can be used to correct the amount of liquid fuel so that the combined mixture of gaseous and liquid fuel produces the desired air-fuel mixture when combined with the air entering the engine cylinders. The pressure of the gaseous fuel stored in the storage gas tank continues to decrease as the gaseous fuel is consumed by the engine.

At time T ₄ , the pressure in the intake manifold of the engine rises to a level greater than the ambient air pressure, which means that the gaseous fuel injector injects into the inlet or central injection and the gaseous fuel flow to the engine is temporarily stopped. Decommissioning a gaseous fuel nozzle reduces the likelihood of outside air entering the gas storage tank when the pressure in the intake manifold is high. In this way, air can be prevented from entering the storage tank at higher pressures in the intake manifold and lower pressures in the storage tank. The pressure in the intake manifold can reach pressures higher than the ambient pressure when the compressor raises the pressure of the air entering the engine.

At time T ₄ , the pressure in the intake manifold of the engine decreases to a level lower than the ambient pressure, and the gaseous fuel nozzle is reactivated. Since the pressure in the intake manifold is lower than the ambient pressure, the intake manifold of the engine can facilitate the flow of gaseous fuel from the storage tank into the engine. Thus, the fuel pressure in the storage gas tank can be reduced with the assistance provided by the low pressure in the intake manifold of the engine. The liquid fuel nozzle continues to deliver fuel to the engine, while the amount of gaseous fuel continues to decrease.

At time T ₅ , the pressure in the storage gas tank is reduced to ambient pressure, and the gaseous fuel nozzle is taken out of operation in order to prevent the ambient air from penetrating into the storage gas tank. In addition, the disengagement of the gaseous fuel nozzle when the pressure in the gaseous fuel tank reaches ambient pressure prevents the formation of a vacuum in the storage gas tank, so that no flow is caused between the atmosphere and the gaseous fuel tank. The liquid fuel nozzle delivers fuel to the engine alone after a time T ₅ , and the amount of liquid fuel is related to the engine load, which may affect the pressure in the intake manifold of the engine. In other examples, the gaseous fuel tank may be reduced to a predetermined vacuum, if required. Thus, the pressure in the gaseous fuel tank can be reduced, so that essentially all of the fuel in the gas storage tank can be used to generate energy to drive the engine. In addition, a smooth transition between engine operation exclusively using gaseous fuel and engine operation exclusively using liquid fuel is thus ensured.

With reference to FIG. 6 shows a second simulated operating sequence according to the method of FIG. 7. The sequence of FIG. 6 includes graphs similar to those shown in FIG. 5. Therefore, a description of similar graphs is omitted for the sake of brevity. The differences between the figures are described. The sequence of FIG. 6 may be provided by the system of FIG. 1 according to the method of FIG. 7. Vertical labels are shown at times T ₀ -T ₆ to identify specific points of interest of interest during the sequence.

The example of FIG. 6 differs from the example in FIG. 5 for the reason that the engine receives directly injected gaseous fuel. Direct injection requires a fairly high injection pressure if the injection occurs after the inlet valve is closed, thus leaving more pressure in the tank than might be required during refueling. This example transfers the fuel supply from direct gas injection after IVC to direct injection to IVC, and then, possibly PFI or CFI subsequently. As gaseous fuel supply restrictions are met, gaseous fuel is supplemented by liquid fuel. In addition, the setting of the distribution phases of the intake valves can be varied to improve the increase in vacuum in the engine, thus allowing additional emptying of the gaseous fuel tank.

The third graph from above in FIG. 6 shows the amount of gaseous fuel injected through the ^1st nozzle of gaseous fuel direct injection into the engine cylinder. The Y axis represents the amount of gaseous fuel injected into the engine through the direct injection gaseous fuel nozzle. The amount of gaseous fuel increases in the direction of the arrow of the Y axis. The X axis represents time, and time increases on the left side of FIG. 6 to the right side of FIG. 6.

The fourth graph from above in FIG. 6 shows the amount of gaseous fuel injected through the ^2nd nozzle of the gaseous fuel injection into the inlet channel or the central injection into the engine intake system. The Y axis represents the amount of gaseous fuel injected into the engine through the gaseous fuel nozzle of the injection into the inlet or central injection. The amount of gaseous fuel increases in the direction of the arrow of the Y axis. The X axis represents time, and time increases on the left side of FIG. 6 to the right side of FIG. 6.

The fifth graph from above in FIG. 6 is a signal that indicates the removal of gaseous fuel nozzles from operation. The direct injection gaseous fuel injector is shut down when the signal is at an average level. Both the direct injection gaseous fuel injector and the gaseous fuel injection nozzle into the inlet or central injection are taken out of operation when the signal is at the upper level. Both the direct injection gaseous fuel injector and the gaseous fuel injection nozzle in the inlet or central injection are effective when the signal is at a lower level, but are not necessarily injecting gaseous fuel.

A horizontal mark 602 represents ambient pressure. The pressure above the horizontal mark 602 is higher than the ambient pressure. The pressure below the horizontal mark 602 is lower than the ambient pressure. The horizontal mark 604 represents the first threshold pressure in the tank, where the engine is controlled to continue to allow the direct injection fuel nozzle to continue to inject gaseous fuel into the cylinder. The horizontal mark 606 represents the second threshold pressure in the tank where the direct-injection gaseous fuel injector is taken out of operation. Horizontal mark 608 represents the third threshold pressure in the tank where liquid fuel injection begins, while gas flow through the fuel injection nozzle into the inlet or central injection slows down, but continues.

At time T ₀ , the pressure in the intake manifold is low, indicating that the engine is operating at low load. The liquid fuel nozzle does not inject fuel into the engine and is not a gaseous fuel nozzle of either injection into the inlet or central injection. The direct injection gaseous fuel injector delivers fuel to the engine, and the pressure in the storage gas tank is relatively high.

Between time T ₀ and time T ₁ , the pressure in the intake manifold of the engine rises and falls depending on the engine load. The direct-injection gaseous fuel injector is pressurized, which allows direct injection into the engine at a compression stroke. Air entering the engine can be compressed by a compressor. The inlet valve of the cylinder receiving the gaseous fuel can open at +20 degrees of the crankshaft rotation angle from top dead center in the intake stroke during this time. The pressure in the gas storage tank decreases as the engine continues to run.

At time T ₁ , the pressure in the storage gas tank reaches the first threshold pressure in the tank, and the engine is controlled to allow continued fuel injection through the direct injection gaseous fuel nozzle. In one example, setting the moment of fuel injection moves from the compression stroke to the intake stroke when the pressure in the cylinder is lower. As a result, fuel continues to flow through the direct injection gaseous fuel injector. In addition, the opening time of the intake valve can be delayed later than 20 degrees of the crankshaft angle after the top dead center of the intake stroke in order to reduce the pressure in the cylinder during fuel injection.

At time T ₂ , the pressure in the storage gas tank reaches a second threshold pressure in the tank, where the direct injection gaseous fuel nozzle is taken out of operation, and the fuel starts to flow through the gaseous fuel injection nozzle into the inlet or central injection. Since the vacuum in the intake manifold may be low, the injection of gaseous fuel through the gaseous fuel nozzle of the central injection begins to drain the storage tank further. The gaseous fuel continues to flow out through the central gas nozzle or the injection into the inlet between the time T ₂ and T ₃ .

At time T ₃ , the pressure in the storage gas tank reaches a third threshold pressure in the tank, where the liquid fuel nozzle begins to inject fuel into the engine to promote sustainable combustion, when there may be pressure in the storage gas tank insufficient to drive the engine with the torque required by the driver. Gaseous fuel also continues to flow into the engine at a lower flow rate, further emptying the gas storage tank.

Between time T ₄ and time T ₅ , the pressure in the intake manifold rises to a level greater than the ambient pressure. The gaseous fuel injector injection into the inlet channel or the central injection is temporarily taken out of operation, and the flow of gaseous fuel into the engine is stopped. The injection of gaseous fuel into the engine continues after time T ₅ .

At time T ₆ , the pressure in the storage gas tank reaches ambient pressure, and both nozzles of the gaseous fuel, direct and injection into the inlet channel are taken out of operation. Liquid fuel continues to be injected into the engine based on engine load.

Thus, in some examples, both nozzles of gaseous fuel, direct and injection into the inlet can be actuated to empty the gaseous fuel storage tank. Although FIG. 5 and 6 mention gaseous fuel nozzles, the description is not limited to gaseous fuels and applies to other gases such as nitrous oxide.

Next, with reference to FIG. 7, a flowchart of an exemplary method for emptying a pressurized tank is shown. The method can be stored as executable instructions in read-only memory in the controller and system, as shown in FIG. 1. The method may include the sequences of FIG. 5 and 6.

At 740, method 700 includes determining whether a diagnostic code has been set in response to a leak in the gas fuel system. If the controller 12 determines that a diagnostic code indicating a leak has been set, then the flow restriction valve may also be closed to restrict the flow of gas from the storage fuel tank. Since the gas flow is shut off, the method 700 further includes means for operating the fuel supply system in the default mode, which is indicated at step 742. In the default mode, the controller 12 includes a fuel pump 248 for supplying liquid fuel 244 from the liquid tank 240 fuel to the fuel distribution rail 67 to power the engine 10. Returning to step 740, if the controller 12 determines that a diagnostic code indicating a leak has not been set, the fuel supply system 200 may continue to operate as intended, and Supply fuel based on the amount of gaseous fuel remaining in the fuel tank 91 and the torque required by the driver.

At 702, method 700 determines engine operating conditions. Engine operating conditions may include, but are not limited to, engine speed, engine load, gaseous fuel pressure, ambient temperature, and engine coolant temperature. Method 700 proceeds to step 704 after engine operating conditions are determined.

At 704, method 700 evaluates whether or not the direct injection gaseous fuel injector engine is included. The configuration of the engine fuel injectors can be stored. If method 700 concludes that the engine includes direct injection gaseous fuel nozzles, the answer is “Yes,” then method 700 proceeds to step 706. Otherwise, the answer is “No,” and method 700 proceeds to step 720.

At step 706, method 700 evaluates whether or not the pressure of the gaseous fuel is greater than the first threshold pressure in the tank. If method 700 concludes that the pressure of the gaseous fuel is greater than the first threshold pressure in the tank, the answer is “Yes,” then method 700 proceeds to step 714. Otherwise, the answer is “No,” and method 700 proceeds to step 708. Pressure gaseous fuels can be read inside the gas storage tank or along a pipe or channel between the storage tank and the engine. In one example, the pressure of the gaseous fuel is determined inside the fuel rail at a location downstream of the pressure regulator.

At 714, method 700 drives the engine by injecting gaseous fuel through a direct injection gaseous fuel injector. The direct injection gaseous fuel injector injects gaseous fuel in the first part of the compression stroke; however, gaseous fuel injection may start later in the intake stroke (for example, 20 degrees of crankshaft rotation to bottom dead center in the intake stroke). The intake valve distribution phase setting is also set to base the valve distribution phase setting, where the intake valve opens at ± 20 degrees of crankshaft rotation from top dead center in the intake stroke. Method 700 proceeds to step 716 after the gaseous fuel injection time is determined and issued.

At step 716, method 700 deactivates the injection of liquid fuel (eg, injection of gasoline fuel). Liquid fuel injection is taken out of operation to conserve liquid fuel. In one example, liquid fuel can be stored for cold starting. Thus, the engine can be started using liquid fuel, and then proceed to work exclusively using gaseous fuel. The method 700 proceeds to exit after the injection of liquid fuel is taken out of operation.

At 708, method 700 controls the direct injection of gaseous fuel to inject most of the gaseous fuel during a cylinder intake stroke. For example, 80% of the gaseous fuel injected during a cylinder cycle can be injected at the cylinder intake stroke. Additionally, the engine torque value may be limited to less than the threshold torque value in this mode, since gaseous fuel displaces fresh air from part of the cylinder volume while the intake valve is open. If the torque required by the driver is greater than the threshold torque of the engine, the fuel oil injection may be actuated to provide the desired engine torque. Additionally, in one example, the timing of the opening of the intake valve (IVO) is adjusted to be late in the intake stroke (for example, it is delayed to at least 20 degrees from the crankshaft after the top dead center in the intake stroke). In other examples, the IVO may be delayed later than 90 degrees of the crankshaft angle after top dead center in the intake stroke. The method 700 proceeds to step 710 after the setting of the moment of direct injection of gaseous fuel and the setting of the distribution phases of the intake valves are configured.

At step 710, method 700 evaluates whether or not the pressure of the gaseous fuel is greater than the second threshold pressure in the tank. If so, the answer is “Yes”, then the method 700 proceeds to the exit, and the fuel is directly injected, and the setting of the distribution phases of the intake valves is controlled according to 708. Otherwise, the answer is “No”, and the method 700 proceeds to step 712.

At 712, method 700 deactivates the direct injection of the gaseous fuel nozzle, and the injection of the gaseous fuel directly into the engine cylinder is stopped. The direct injection gaseous fuel injector can be taken out of operation by simply issuing a shutdown command to the direct injection gaseous fuel injector. Method 700 proceeds to step 720 after the gaseous fuel nozzle is taken out of operation.

At step 720, method 700 drives the injection of gaseous fuel with an injection into the inlet or central injection when an injection into the inlet or central injection of the gaseous fuel is available. Injection into the inlet or central injection of gaseous fuel may be available with liquid and direct injection of gaseous fuel, as shown in FIG. 1. In addition, the fuel injection system may include injection into the inlet or central injection of gaseous fuel and injection of liquid fuel without direct injection of gaseous fuel. The method 700 proceeds to step 722 after the injectors of the gaseous fuel injection into the inlet or central injection are actuated.

At 722, method 700 evaluates whether or not the pressure of the gaseous fuel in the gaseous fuel storage tank or in the fuel rail is greater than the third threshold pressure in the tank. If so, the answer is “Yes”, then the method 700 proceeds to step 724. If not, the answer is “No”, then the method 700 proceeds to step 726.

At step 724, method 700 injects gaseous fuel through a fuel injection nozzle into an inlet or central injection based on engine operating conditions (e.g., rotation speed and engine load). In addition, the installation of the valve valve distribution phases may be a predetermined basic setting of the valve distribution phases, where the intake valves open within ± 20 degrees of the crankshaft angle of rotation from the top dead center of the starting stroke. In some examples, the liquid fuel injection may be actuated when the torque required by the driver is higher than a threshold value, so that the engine can satisfy the torque required by the driver. Method 700 proceeds to exit after gaseous fuel injectors inject gas into the engine inlet or central injection into the engine according to engine operating conditions.

At step 726, method 700 drives liquid fuel injection and adjusts the desired exhaust gas lambda value. The exhaust gas lambda value is the oxygen concentration of the exhaust gas produced by the stoichiometric air-fuel ratio divided by the desired or actual air-fuel ratio. Thus, the air-fuel mixture in the engine is depleted when the lambda is greater than 1, and the air-fuel mixture in the engine is enriched when the lambda value is less than 1. Feedback on the lambda value is provided by the oxygen sensor in the exhaust system. In one example, the amount of gaseous fuel entering the cylinder is estimated from the pressure of the gaseous fuel and the nozzle over time. If there is insufficient flow of gaseous fuel into the cylinder to provide the required engine torque level, liquid fuel is injected along with the gaseous fuel to satisfy the required engine torque. For example, if the required engine torque is 200 N ∙ m and the injected amount of gaseous fuel can provide 60 N ∙ m, the fuel oil nozzle is turned on to provide 140 N ∙ m of torque. The amount of air in the engine is adjusted to provide the desired lambda value by adjusting the position of the throttle or setting the valve distribution phases. Thus, when the pressure in the intake manifold of the engine is increasing due to an increase in engine load, the flow of gaseous fuel decreases and the flow of liquid fuel increases. In addition, when the pressure in the intake manifold of the engine decreases due to the reduced engine load, the percentage of liquid fuel supplied to the engine relative to the total amount of fuel supplied to the engine decreases. Method 700 proceeds to step 728 after the quantities of gaseous and liquid fuels are dispensed.

At step 728, method 700 evaluates whether or not the absolute pressure in the manifold is greater than the pressure of the gaseous fuel in the storage tank or in the fuel rail. If so, the answer is “Yes”, then the method 700 proceeds to step 732. Otherwise, the answer is “No”, and the method 700 proceeds to step 730.

At step 730, method 700 evaluates whether or not the pressure of the gaseous fuel in the storage tank or fuel rail is within the threshold pressure at ambient pressure. For example, method 700 estimates whether or not the pressure in the storage tank is within 1 bar of atmospheric pressure. If the pressure of the gaseous fuel is within the threshold pressure at ambient pressure, method 700 proceeds to step 732. Otherwise, method 700 proceeds to exit.

At step 732, method 700 deactivates the injection of gaseous fuel into the engine. Gaseous fuel injection can be taken out of operation by simply giving a command to the gaseous fuel nozzle to an off state. The gaseous fuel nozzle can be taken out of operation until the gaseous fuel tank is refilled. Method 700 proceeds to exit after gaseous fuel injection is taken out of operation.

Thus, method 700 can begin to inject gaseous fuel through a direct injection nozzle and transfer to gaseous fuel injection through injection nozzles into the inlet or central injection. In addition, method 700 can shut down all gaseous fuel nozzles when the pressure in the gaseous fuel storage tank is less than the threshold pressure in the tank. Thus, the operation of the engine and the gaseous fuel nozzle can be controlled to reduce the pressure and the amount of gaseous fuel in the gaseous fuel storage tank.

Thus, the method of FIG. 7 provides a method for emptying a tank, which includes supplying exclusively gaseous fuel to the engine when the pressure of the gaseous fuel is greater than a threshold pressure in the tank; and supplying gaseous fuel and liquid fuel when the pressure of the gaseous fuel is less than the threshold pressure in the tank. In this way, the engine can continue to operate and give out torque, while the additional gas is drawn from the gaseous fuel storage tank. The method further comprises disabling the fuel injector, which is supplied with gaseous fuel when the pressure in the intake manifold of the engine is greater than the ambient pressure.

In yet another example, the method further includes disabling the fuel injector, which is supplied with gaseous fuel when the pressure of the gaseous fuel is substantially at ambient pressure. The method also includes those cases where a fuel injector that is fed with gaseous fuel injects gaseous fuel into the intake manifold. The method includes those cases when the pressure of the gaseous fuel is within the storage tank. The method also includes those cases where the pressure of the gaseous fuel is within the channel between the storage tank and the engine.

In yet another example, the method of FIG. 7 provides a method for emptying a tank, including supplying gaseous fuel to the engine through the tank; the operation of the engine on gaseous fuel and with the first installation of the valve distribution phases in the first state, when the pressure of the gaseous fuel is greater than the first threshold pressure in the tank; and the operation of the engine on gaseous fuel and with a second setting of valve distribution phases in a first state when the pressure of the gaseous fuel is less than the first threshold pressure in the tank. Thus, the setting of the distribution phases of the intake valves can be adjusted to increase the amount of vacuum in the cylinder, thereby causing flow from the storage gas tank to the engine.

The method includes cases where the first state is the rotational speed and engine load. The method also includes cases where the engine inlet valve opens later relative to the crankshaft position, when the pressure of the gaseous fuel is less than the first threshold pressure in the tank, compared to when the inlet valve opens when the pressure of the gaseous fuel is greater than the first threshold pressure in the fuel tank. The method further comprises injecting gaseous fuel into the engine cylinder at a cylinder inlet stroke when the pressure of the gaseous fuel is less than the first threshold pressure in the tank. The method further comprises injecting gaseous fuel into the engine cylinder at a compression stroke of the cylinder when the pressure of the gaseous fuel is greater than the first threshold pressure in the tank. The method further comprises directly injecting gaseous fuel into the engine cylinder through the nozzle and disengaging the nozzle when the pressure in the tank is substantially at ambient pressure.

In yet another example, the method of FIG. 7 provides a method for emptying a tank, including supplying gaseous fuel to the engine through the tank; engine operation on the first gaseous fuel nozzle when the gaseous fuel pressure is greater than the first threshold pressure in the tank; and engine operation on the second gaseous fuel nozzle when the gaseous fuel pressure is less than the first threshold pressure in the tank. The method includes those cases where the first gaseous fuel nozzle injects gaseous fuel directly into the cylinder, and when the second gaseous fuel nozzle injects gaseous fuel into the intake manifold. The method also includes those cases where the first gaseous fuel nozzle is shut down, when the gaseous fuel pressure is less than the first threshold pressure in the tank. The method also includes those cases when the second gaseous fuel nozzle is shut down, when the pressure gaseous fuel is substantially at ambient pressure.

In yet another example, the method further includes commissioning the liquid fuel nozzle when the pressure of the gaseous fuel is less than the second threshold pressure in the tank. The method further comprises adjusting the fuel-air ratio of the engine in response to the output of the oxygen sensor by adjusting the setting of the injection timing of the liquid fuel nozzle. The method further comprises delaying the installation of the opening moment of the engine intake valve in response to gaseous fuel pressure, while the first gaseous fuel nozzle is actuated while the second gaseous fuel nozzle is not actuated. The method further comprises disabling the second nozzle of the gaseous fuel when the pressure in the intake manifold is greater than the ambient pressure. Although some examples describe gaseous fuel injection, it should be understood that other non-fuel gases can also be injected as described herein.

This completes the description. Reading it by experts in the field of technology would recall many changes and modifications without leaving the essence and scope of the description. For example, in-line engines I3, I4, I5, V-engines V6, V8, V10 and V12 operating on natural gas, gasoline, diesel fuel or alternative fuel configurations could use the present description to take advantage.

Claims (14)

1. The method of emptying the tank, which includes stages in which: empty the fuel tank by supplying only gaseous fuel to the engine at high pressure in the gaseous fuel tank and supplying gaseous fuel and liquid fuel at low pressure in the gaseous fuel tank; and stop emptying by closing the valve of the gaseous fuel tank in response to a low pressure downstream of the valve of the gaseous fuel tank and high pressure in the tank. 2. The method according to claim 1, further comprising the step of disabling the operation of the fuel injector, which is supplied with gaseous fuel, when the pressure in the intake manifold of the engine is greater than the ambient pressure, wherein the termination further includes the step of which switch the fuel source. 3. The method of claim 2, further comprising the step of disabling the fuel injector, which is supplied with gaseous fuel when the pressure of the gaseous fuel is substantially at ambient pressure. 4. The method of claim 3, wherein the fuel injector, which is fed with gaseous fuel, injects gaseous fuel into the intake manifold. 5. A method of emptying a tank, comprising the steps of: supplying gaseous fuel to the engine from the tank; carry out the operation of the engine on gaseous fuel and with the first installation of the valve distribution phases in the first state, when the pressure of the gaseous fuel is greater than the first threshold value; operating the engine on gaseous fuel and with a second setting of valve distribution phases in a first state when the pressure of the gaseous fuel is less than the first threshold value; and the supply is stopped based on the pressure difference in the gaseous fuel tank and the pressure in the gas rail distributor greater than a threshold value, wherein the pressure in the gaseous fuel tank is greater than the pressure in the gas rail distributor. 6. The method according to claim 5, wherein the first state is the rotational speed and engine load, the cessation of which includes closing the valve of the gaseous fuel tank, wherein the pressure in the gaseous fuel tank is based on the pressure sensor of the gaseous fuel tank. 7. The method of claim 5, wherein the engine inlet valve is opened later relative to the crankshaft position when the gaseous fuel pressure is less than the first threshold value, compared to when the inlet valve is opened when the gaseous fuel pressure is greater than the first threshold value. 8. The method according to claim 5, further comprising the step of injecting gaseous fuel into the engine cylinder at a cylinder inlet stroke when the pressure of the gaseous fuel is less than the first threshold value.

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