JP2008002301A - Vehicle fuel supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fuel supply apparatus for a vehicle capable of preventing actuation of a means that actuates during excessive flow of fuel even when a communication valve is opened under such a condition that pressures of a plurality of fuel tanks are different from each other. <P>SOLUTION: Fuel pipes 18A, 18B for respectively supplying fuel to an engine 42 from the two fuel tanks 14A, 14B are connected to each other by a bypass pipe 30. The fuel pipes 18A, 18B can be communicated with each other by opening a bypass valve 32. When an ignition key of a vehicle is turned "ON" under such a condition that the pressure of the fuel tank 14A is higher than that of the fuel tank 14B, the bypass valve 32 is opened and the fuel flows from the high-pressure side fuel pipe 18A to the low-pressure side fuel pipe 18B, so that the pressures of the fuel tanks become equal to each other. Thereafter, since main valves 20A, 20B are opened, the actuation of an excessive flow prevention valve 24A is prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle fuel supply apparatus.

  In a vehicular fuel supply device that supplies compressed natural gas (CNG) to an engine as a fuel, for example, as described in Patent Document 1, a fuel overflow detection valve is provided in a high-pressure piping, and this overflow detection valve is provided. Some have a fuel overflow prevention device that closes the container base valve when a sudden pressure change is detected.

By the way, as described in Patent Document 1, in a configuration in which fuel is supplied from a plurality of fuel tanks to an engine, generally, a plurality of fuel supply systems corresponding to the plurality of fuel tanks are communicated by a communication valve or the like. Often. However, when there is a pressure difference between multiple fuel tanks, fuel may temporarily flow from the relatively high pressure fuel tank to the low pressure fuel tank depending on the timing of opening the communication valve. is there. At this time, the overflow operation means (such as an overflow prevention valve provided in the fuel tank) is activated.
Japanese Patent Laid-Open No. 10-252568

  In view of the above facts, the present invention has an object to obtain a vehicular fuel supply device capable of suppressing the operation of the operation means at the time of overflow even if the communication valve is opened in a state where there is a pressure difference in a plurality of fuel tanks To do.

  According to the first aspect of the present invention, a plurality of fuel tanks that store fuel, a plurality of fuel supply systems that respectively supply fuel from the plurality of fuel tanks to the engine, and the fuel for the fuel supply system A tank opening / closing valve for opening and closing the tank, an overflow operation means for performing a predetermined operation in response to an overflow of fuel from the fuel tank to the corresponding fuel supply system, and a communication valve for communicating the plurality of fuel supply systems And a suppression means that suppresses the predetermined operation of the overflow operation means when both the tank on-off valve and the communication valve shift from the closed state to the open state.

  In this vehicle fuel supply device, when the tank opening / closing valve is opened, fuel is supplied from the fuel tank to the engine through the fuel supply system. Further, in the state where the communication valve is opened, the pressure difference in the plurality of fuel supply systems is eliminated. At this time, when fuel overflow occurs from the fuel tank to the fuel supply system, the overflow operation means performs a predetermined operation. Thereby, overflow is suppressed or stopped.

  Here, in the present invention, when the tank on-off valve and the communication valve shift from the closed state to the open state, the suppressing means suppresses the predetermined operation of the overflow operating means. That is, when pressure differences occur in a plurality of fuel tanks, even if the tank opening / closing valve and the communication valve are opened, the predetermined operation of the overflow operation means is suppressed by the suppression means.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the overflow operation means is an overflow prevention valve that closes the overflow and prevents overflow. To do.

  That is, when an overflow of fuel from the fuel tank to the fuel supply system occurs, the overflow prevention valve that is the operation means at the time of overflow closes. Thereby, the overflow from the fuel tank to the fuel supply system is stopped.

  When the tank opening / closing valve and the communication valve are opened while there is a pressure difference in the fuel tank, the closing of the overflow prevention valve is suppressed by the suppression means.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the suppression means is configured such that the pressure difference between the fuel tank and the fuel supply system corresponding to the fuel tank is equal to or greater than a set value. A flow rate limiting means for limiting the flow rate of fuel from the fuel tank to the fuel supply system, and a pressure for opening the tank on-off valve and the communication valve after the pressure difference between the plurality of fuel supply systems is reduced Difference control means.

  That is, when the pressure difference between the plurality of fuel supply systems is reduced, the pressure decreases in the fuel supply system that was at a relatively high pressure before the pressure difference was reduced, and this fuel supply system and the corresponding fuel tank A pressure difference will occur (or the pressure difference will increase). When the pressure difference is equal to or greater than the set value, the fuel supply from the fuel tank to the fuel supply system is suppressed by the flow rate limiting means. As a result, since the fuel flows from the fuel tank to the fuel supply system, the pressure difference between the fuel tank and the fuel supply system is reduced. Further, in the state after the pressure difference between the plurality of fuel supply systems is reduced, the tank opening / closing valve and the communication valve are in the open state, but the overflow from the fuel tank to the corresponding fuel supply system Is suppressed, so that the predetermined operation of the overflow operation means is also suppressed.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the pressure difference control means opens the communication valve before the tank opening / closing valve is opened.

  As described above, the predetermined operation of the overflow operation means can be suppressed with a simple configuration in which the communication valve is opened before the tank opening / closing valve is opened.

  Note that the “predetermined operation” of the overflow operation means according to the inventions of claims 1 to 4 includes, in addition to stopping the outflow of fuel from the fuel tank to the fuel supply system, as can be seen from the above. It also includes reducing the flow rate. In other words, an operation for suppressing fuel overflow from the fuel tank to the fuel supply system is included. On the other hand, the “flow rate limiting means” described in claim 3 limits the fuel flow rate from the fuel tank to the fuel supply system, but does not suppress the overflow itself.

  Since the present invention has the above-described configuration, the operation of the overflow operation means can be suppressed even if the communication valve is opened in a state where there are pressure differences among the plurality of fuel tanks.

  FIG. 1 shows a schematic configuration of a fuel supply device 12 according to the first embodiment of the present invention. The fuel supply device 12 is applied to an automobile that uses compressed natural gas (CNG) as fuel.

  The fuel supply device 12 has a plurality (two in this embodiment) of fuel tanks 14A and 14B in which compressed natural gas (CNG) is accommodated. Fuel pipes 18A and 18B are connected to the fuel tanks 14A and 14B via tank main valves 16A and 16B, respectively. In the present embodiment, the fuel pipes 18A and 18B are connected to the injectors of the two banks 44A and 44B of the V-type engine 42, for example, one to one so as to supply fuel. Instead of this, for example, a configuration in which a plurality of fuel pipes 18A and 18B are connected to one injector may be employed, and the correspondence between the fuel pipe and the injector is not particularly limited.

  Each of the tank main valves 16A and 16B has pilot valves 22A and 22B and overflow prevention valves 24A and 24B in addition to the main valves 20A and 20B. Even if the pilot valves 22A and 22B perform the valve opening operation to open the main valves 20A and 20B, the internal pressures of the corresponding fuel pipes 18A and 18B with respect to the internal pressures of the fuel tanks 14A and 14B are higher than a predetermined value set in advance. When it is low, the valve is opened before the main valves 20A and 20B, and the fuel is gradually sent from the fuel tanks 14A and 14B to the corresponding fuel pipes 18A and 18B. The main valves 20A and 20B are opened when the pressure difference between the fuel tanks 14A and 14B and the corresponding fuel pipes 18A and 18B is equal to or less than the set value (preferably, the pressure difference is eliminated). Structure.

  The overflow prevention valves 24A and 24B are normally open, but fuel overflow (a large amount of fuel flows in a short time from the fuel tanks 14A and 14B toward the corresponding fuel pipes 18A and 18B). It has a function of closing the valve when it is about to occur and preventing this overflow.

  Each of the fuel pipes 18A and 18B is provided with pressure reducing valves 26A and 26B in front of the engine 42 (on the fuel tanks 14A and 14B side), and the engine in a state where the fuel in the fuel pipes 18A and 18B is decompressed. 42 can be supplied.

  Further, pressure sensors 28A and 28B are provided on the fuel tanks 14A and 14B side further than the pressure reducing valves 26A and 26B. These pressure sensors 28A and 28B can detect the pressures in the corresponding fuel pipes 18A and 18B. As shown in FIG. 2, data detected by the pressure sensors 28 </ b> A and 28 </ b> B is sent to the control circuit 34.

  The fuel pipes 18A and 18B are connected by a bypass pipe 30. A bypass valve 32 is disposed in the bypass pipe 30, and the fuel pipes 18 </ b> A and 18 </ b> B can be communicated by opening the bypass valve 32.

  The main valves 20A and 20B of the tank main valves 16A and 16B, the pilot valves 22A and 22B, the overflow prevention valves 24A and 24B, and the bypass valve 32 are all electromagnetic valves in this embodiment, and are shown in FIG. As described above, the control circuit 34 controls the opening and closing. Further, the control circuit 34 is also input with the state (on / off) of an ignition key (not shown) of the automobile.

  Next, the operation of the fuel supply device 12 of this embodiment will be described.

  As shown in the timing chart of FIG. 3, before the engine is started (when the engine is started is indicated by T1), the bypass valve 32 is in a closed state, and the main valves 20A and 20B are also closed. Therefore, the fuel does not inadvertently flow out from the fuel tanks 14A and 14B to the fuel pipes 18A and 18B. In the present embodiment, the case where a pressure difference occurs between the fuel tanks 14A and 14B (between the fuel pipes 18A and 18B) at this stage (the fuel tank 14A is higher in pressure than the fuel tank 14B) will be described below. . In general, the fuel tanks 14A and 14B and the corresponding fuel pipes 18A and 18B have the same pressure.

  Here, when the ignition key of the automobile is set to “On” at the timing indicated by T <b> 1 in FIG. 3, the control circuit 34 first energizes the bypass valve 32 to open the valve. As a result, fuel flows from the high-pressure side fuel pipe 18A to the low-pressure side fuel pipe 18B through the bypass pipe 30, and these pressures become equal (this timing is indicated by T2). After the fuel pipes 18A and 18B are at the same pressure in this way, in other words, the control circuit 34 is in a state where the internal pressure of the corresponding fuel pipe 18A is lower than the relatively high pressure fuel tank 14A. The valves 20A and 20B are energized to open. That is, the state where both the main valves 20A and 20B and the bypass valve 32 are opened is realized in a state where the pressure difference between the fuel pipes 18A and 18B is reduced.

  Here, as in this embodiment, the case where the bypass valves 32 and the main valves 20A and 20B are opened at the same time instead of opening the main valves 20A and 20B after the bypass valve 32 is opened is considered. In this case, since the main valves 20A and 20B are opened in a state where the fuel pipes 18A and 18B are not at the same pressure, the relatively high pressure fuel tank 14A is changed to the low pressure fuel tank 14B. There is a risk that the fuel will flow at a stretch and the high pressure side overflow prevention valve 24A will be activated.

  In contrast, in the present embodiment, as described above, the bypass valve 32 is first opened to make the fuel pipes 18A and 18B have the same pressure, so that the corresponding fuel is supplied to the high-pressure side fuel tank 14A. The pipe 18A has a lower pressure than before the bypass valve 32 is opened. That is, a pressure difference is generated between the fuel tank 14A and the fuel pipe 18A (if there is already a pressure difference, the pressure difference increases). Accordingly, when the main valves 20A and 20B are subsequently opened, the pilot valve 22A is opened before the main valve 20A, and the fuel gradually flows from the fuel tank 14A to the fuel pipe 18A, so that the pressure between the fuel tank 14A and the fuel pipe 18A is increased. The difference is reduced (preferably eliminated). Thus, fuel flows from the fuel tank 14A to the fuel pipe 18A in a state where the operation of the overflow prevention valve 24A is suppressed. In this way, by suppressing the operation of the overflow prevention valve 24A (not to close the overflow prevention valve 24A), it is possible to prevent a situation where the supply of fuel to the engine 42 is stopped and It becomes possible to supply fuel to the engine 42.

  Moreover, since the bypass valve 32 is simply opened before the main valves 20A and 20B are opened, no complicated structure or control is required.

  In the above description, the case where the fuel tank 14A has a relatively high pressure relative to the fuel tank 14B has been taken as an example. However, when the fuel tank 14B has a relatively high pressure relative to the fuel tank 14A, the fuel tanks 14A and 14B. As for the fuel pipes 18 and 18B, the operation is symmetrical to the above.

  As described above, in the fuel supply device 12 of the present embodiment, the bypass valve 32 is opened before the main valves 20A and 20B of the fuel tanks 14A and 14B are opened. Therefore, there is a pressure difference between the fuel tanks 14A and 14B. Even in some cases, the operation of the overflow prevention valves 24A and 24B can be suppressed.

  In the above-described embodiment, the case where the internal pressures of the fuel pipes 18A and 18B detected by the pressure sensors 28A and 28B are equal is used as a determination index for the timing of opening the main valves 20A and 20B. The determination index is not limited to this. For example, even if the internal pressures of the fuel pipes 18A and 18B are not equal, the main valves 20A and 20B may be opened with a pressure difference within a predetermined value set in advance. In any configuration, the valve opening control of the main valves 20A and 20B can be reliably performed based on the detection results by the pressure sensors 28A and 28B.

  Furthermore, regardless of the pressure difference between the fuel pipes 18A and 18B, a change in pressure of each of the fuel pipes 18A and 18B is detected, and when the pressure change disappears or when the pressure change becomes gentle, the fuel pipe 18A , 18B, the main valve 20A, 20B may be opened, assuming that the pressure difference is also reduced.

  In addition, the timing for opening the main valves 20A and 20B from the state of the bypass valve 32 may be obtained. For example, the current value to the solenoid valve coil that constitutes the bypass valve 32 may be used as a basis. Alternatively, the main valves 20A and 20B may be opened, assuming that the pressure difference between the fuel pipes 18A and 18B has decreased after a predetermined time has elapsed since the bypass valve 32 was opened. In these configurations, the pressure sensor 28A is unnecessary.

  In the above description, the main valve 20A, 20B, the pilot valves 22A, 22B and the overflow prevention valves 24A, 24B of the tank main valves 16A, 16B are all controlled by the control circuit 34. It is sufficient that at least the main valves 20A and 20B are controlled.

  In the above description, the fuel supply device having the configuration including two fuel tanks and fuel pipes is described. However, the present invention can also be applied to a configuration having more fuel tanks and fuel pipes.

It is a schematic block diagram which shows the fuel supply apparatus of one Embodiment of this invention. It is a block diagram of the fuel supply apparatus of one Embodiment of this invention. It is a timing chart which shows the valve opening timing of the fuel supply apparatus of one Embodiment of this invention.

Explanation of symbols

12 Fuel supply devices 14A and 14B Fuel tanks 16A and 16B Tank original valves 18A and 18B Fuel piping (fuel supply system)
20A, 20B Main valve (tank open / close valve, pressure difference control means)
22A, 22B Pilot valve (flow restriction means, suppression means)
24A, 24B Overflow prevention valve (operating means during overflow)
26A, 26B Pressure reducing valves 28A, 28B Pressure sensor 30 Bypass pipe 32 Bypass valve (communication valve, pressure difference control means)
34 Control circuit (pressure difference control means, suppression means)
42 Engine (Engine)
44A and 44B banks

Claims (4)

A plurality of fuel tanks containing fuel;
A plurality of fuel supply systems each supplying fuel to the engine from the plurality of fuel tanks;
A tank opening and closing valve for opening and closing the fuel tank with respect to the fuel supply system;
Overflow operation means for performing a predetermined operation with respect to fuel overflow from the fuel tank to the corresponding fuel supply system;
A communication valve for communicating a plurality of the fuel supply systems;
Suppressing means for suppressing the predetermined operation of the overflow operation means when both the tank opening and closing valve and the communication valve are shifted from the closed state to the opened state;
A fuel supply device for vehicles, comprising:   The vehicular fuel supply device according to claim 1, wherein the overflow operation means is an overflow prevention valve that closes the overflow and prevents overflow. The suppression means is
Flow rate limiting means for limiting a fuel flow rate from the fuel tank to the fuel supply system when a pressure difference between the fuel tank and the fuel supply system corresponding to the fuel tank is equal to or greater than a set value;
Pressure difference control means for opening the tank on-off valve and the communication valve after the pressure differences of the plurality of fuel supply systems are reduced; and
The vehicular fuel supply device according to claim 1, wherein the vehicular fuel supply device is provided.   The vehicular fuel supply apparatus according to claim 3, wherein the pressure difference control means opens the communication valve before the tank opening / closing valve is opened.

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