This application claims priority to Japanese patent application serial number 2007-301628, the contents of which are incorporated herein by reference.
The present invention relates to a fuel-feeding system for injecting liquid fuel via a fuel injection valve. Particularly, the present invention relates to a fuel-feeding system for injecting liquid fuel via a fuel injection valve in which a fuel pressure (a pressure of the liquid fuel fed to the fuel injection valve) can be changed, and a three-way valve for use in the fuel-feeding system.
Generally, a vehicle driven by an internal-combustion engine is provided with a fuel-feeding system that is capable of injecting liquid fuel into the internal-combustion engine. Often, the engine of the vehicle is stopped after an engine temperature is raised, and is then restarted. For example, often, the engine is stopped in a rest area of an expressway, and is restated within a short period of time afterward. In such a case, bubbles can be produced in a fuel piping of the fuel-feeding system because the fuel in the fuel piping is still hot. Therefore, the fuel cannot be sufficiently fed to the engine when the engine is restarted. As a result, the engine cannot be smoothly restarted.
Conventionally, in order to increase start-up performance of the engine even if the engine temperature is raised, the fuel-feeding system is constructed such that a fuel pressure (a pressure of the fuel fed to a fuel injection valve) can be temporarily increased when the engine is started. According to this structure, when the engine is started, the bubbles produced in the fuel piping can be compressed, so that the fuel can be sufficiently fed to the fuel injection valve (the engine). As a result, the engine can be smoothly restarted.
For example, in order to increase the fuel pressure when the engine is started, the fuel-feeding system is constructed such that the liquid fuel (low-pressure fuel) fed to the fuel injection valve can be temporarily changed to highly pressurized fuel (high-pressure fuel) when the engine is started. Generally, in order to change the low-pressure fuel to the high-pressure fuel, the fuel-feeding system includes a three-way valve that is disposed in the fuel piping.
An example of the three-way valve is shown in
According to the three-way valve 100, when the magnetic coil 111 is actuated, a valve stem 124a of valve element 124 is projected toward the first valve seat 125A, so that the valve element 124 can contact the first valve seat 125A. At this time, the valve element 124 is moved away from the second valve seat 125B. As a result, the second port 122 is closed, so that first and third ports 121 and 123 can communicate with each other. (Thus, the low pressure fuel pumped through the third port 123 can be fed into the fuel injection valve via the first port 121.) Conversely, when the magnetic coil 111 is deactuated, the valve stem 124a is retracted into the magnetic coil 111, so that the valve element 124 can contact the second valve seat 125B. At this time, the valve element 124 is moved away from the first valve seat 125A. As a result, the third port 123 is closed, so that first and second ports 121 and 122 can communicate with each other. (Thus, the high pressure fuel pumped through the second port 122 can be fed into the fuel injection valve via the first port 121.)
Another example of the three-way valve is disclosed in Japanese Laid-Open Utility Model Publication No. 63-182378. The three-way valve taught by this publication may generally include a valve body portion and a magnetic actuator portion coupled to the valve body portion. The valve body portion includes an inlet port, a first outlet port and a second outlet port. The valve body portion further includes a valve unit that is disposed therein. The valve unit is composed of a valve element and first and second valve seats. Further, the magnetic actuator portion includes a magnetic coil.
According to the three-way valve thus constructed, when the magnetic coil is actuated, the valve element can contact the first valve seat. At this time, the valve element is moved away from the second valve seat. As a result, the second outlet port is closed, so that the inlet port and the first outlet port can communicate with each other. Conversely, when the magnetic coil is deactuated, the valve element can contact the second valve seat. At this time, the valve element is moved away from the first valve seat. As a result, the first outlet port is closed, so that the inlet port and the second outlet port can communicate with each other.
Further, an another fuel-feeding system is disclosed in Japanese Laid-Open Patent Publication No. 2002-339823. In the fuel-feeding system, in order to increase start-up performance of the engine under a condition that the engine temperature is raised, the fuel-feeding system is constructed such that the babble containing fuel (hot fuel) remaining in the fuel piping can be instantly replaced with the fuel (cool fuel) in a fuel tank when the engine is started. In particular, the fuel-feeding system includes first and second fuel pumps and a relief valve that are respectively disposed in the fuel piping. The first and second fuel pumps are arranged so as to be switched between a series arrangement and a parallel arrangement in the fuel piping. Also, the relief valve can be switched between a high pressure position and a low pressure position.
In this structure, when the engine is started (i.e., an ignition is turned on), the first and second fuel pumps are switched to the series arrangement in the fuel piping, and at the same time, the relief valve is switched to the low pressure position. Thereafter, the first and second fuel pumps are operated while the fuel injection valve is not actuated. As a result, the fuel (hot fuel) in the fuel piping can be purged and replaced with the fuel (cool fuel) in the fuel tank. Subsequently, the first and second fuel pumps are switched to the parallel arrangement in the fuel piping, and at the same time, the relief valve is switched to the high pressure position. Thereafter, the first and second fuel pumps are operated, and at the same time, the fuel injection valve is actuated. Thus, the fuel (cool fuel) in the fuel piping can be injected via the fuel injection valve. The fuel (cool fuel) thus injected does not contain the bubbles. Therefore, the fuel can be sufficiently fed to the engine. As a result, the engine can be smoothly restarted even if the engine is in a heated condition.
However, the fuel-feeding system taught by Japanese Laid-Open Patent Publication No. 2002-339823 includes the first and second (two) fuel pumps that can be switched between the series arrangement and the parallel arrangement in the fuel piping. Therefore, a plurality of valves are required in order to switch the fuel pumps between the series arrangement and the parallel arrangement. As a result, the number of components of the fuel-feeding system is increased. This may lead to a complicated structure of the fuel-feeding system. Also, the fuel-feeding system includes the relief valve that can be switched between the high pressure position and the low pressure position. However, such a relief valve may have a complicated structure. This may lead to an increased manufacturing cost of the fuel-feeding system. In addition, such a relief valve cannot be easily switched between the high pressure position and the low pressure position.
Thus, there is a need in the art for an improved fuel-feeding system of an internal combustion engine.
For example, in one embodiment of the present invention, a fuel-feeding system may include a fuel tank containing liquid fuel; a fuel pump capable of pumping the liquid fuel contained in the fuel tank; a fuel injection valve capable of injecting the liquid fuel pumped by the fuel pump; and a three-way valve having a first port, a second port and a third port. The three-way valve is constructed so as to be switched between a first condition in which the first, second and third ports communicate with each other and a second condition in which only the first and third ports communicate with each other. The first port communicates with the fuel pump via a first external conduit. The second port communicates with the fuel tank via a second external conduit having a first relief valve that is set to a first setting pressure. The third port communicates with the fuel tank via a third external conduit having a second relief valve that is set to a second setting pressure higher than the first setting pressure. The fuel injection valve is connected to the third external conduit at a position between the third port and the second relief valve, so that a pressure of the liquid fuel fed to the fuel injection valve can be switched between the first setting pressure and the second setting pressure when the three-way valve is switched between the first condition and the second condition.
According to the fuel-feeding system thus constructed, the liquid fuel pumped by the fuel pump can be adjusted to the first setting pressure or the second setting pressure by simply switching the three-way valve between the first condition and the second condition. Also, the pressure of the pumped liquid fuel can be accurately controlled to the first setting pressure or the second setting pressure by means of the first and second relief valves.
Further, the fuel-feeding system can be structurally simplified. In addition, the pressure of the pumped liquid fuel can be switched between the first setting pressure and the second setting pressure during operation of the fuel-feeding system.
In another embodiment of the present invention, a three-way valve may include a magnetic coil; a valve unit that is actuated by the magnetic coil; a first port, a second port and a third port; a fluid roundabout cavity in which the valve unit is disposed; and a main internal passage that extends along a valve axis of the valve unit. The three-way valve is constructed so as to be switched between a first condition in which the first, second and third ports communicate with each other and a second condition in which only the first and third ports communicate with each other. In the first condition, fluid introduced via the first port can flow through the second and third ports, and in the second condition, the fluid introduced via the first port can flow through the third port without flowing through the second port. The third port is positioned closer to the magnetic coil than the first port. The first and third ports, the main internal passage and the fluid roundabout cavity are arranged and constructed such that the fluid introduced into the main internal passage via the first port can be introduced into the fluid roundabout cavity and then be directed into the third port.
The three-way valve thus constructed result in a simplified structure. Also, the three-way valve may have increased cooling performance of the magnetic coil.
Other objects, features, and advantages, of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.
In the following, a fuel-feeding system according to a detailed representative embodiment of the present invention will be described with reference to
Further, in this embodiment, a fuel-feeding system for an internal-combustion engine is exemplified as the fuel-feeding system.
As shown in
As shown in
The first relief valve 42 may preferably be designed for low pressure service. The first relief valve 42 can be set to a first or low setting pressure with a high degree of accuracy. The first setting pressure may preferably be about 284 kPa. Conversely, the second relief valve 43 may preferably be designed for high pressure service. The second relief valve 43 can be set to a second or high setting pressure with a high degree of accuracy. The second setting pressure may preferably be about 400 kPa.
Therefore, when the liquid fuel is pumped by the fuel pump 41 while the second port 22 of the three-way valve 1 is opened (the first and third ports 21 and 23 of the three-way valve 1 are constantly opened), the first relief valve 42 may suitably function, so that the liquid fuel can be fed into the third external conduit 43A (the delivery tube 44A) at a low pressure corresponding to the first setting pressure. If a pressure of the pumped liquid fuel exceeds the first setting pressure, a portion of the liquid fuel can be discharged into the fuel tank 40 via the first relief valve 42, so that the pressure of the liquid fuel in the third external conduit 43A can be maintained in the first setting pressure. Conversely, when the liquid fuel is pumped by the fuel pump 41 while the second port 22 of the three-way valve 1 is closed, the second relief valve 43 may suitably function, so that the liquid fuel can be fed into the third external conduit 43A (the delivery tube 44A) at a high pressure corresponding to the second setting pressure. If the pressure of the pumped liquid fuel exceeds the second setting pressure, a portion of the liquid fuel can be discharged into the fuel tank 40 through the return pipe 45 via the second relief valve 43, so that the pressure of the liquid fuel in the third external conduit 43A can be maintained in the second setting pressure.
The three-way valve 1 is connected to a control unit (not shown), so as to be switched between a first or low pressure condition and a second or high pressure condition. In the low pressure condition, the second port 22 is opened so that the first, second and third ports 21, 22 and 23 can communicate with each other. Conversely, in the high pressure condition, the second port 22 is closed so that only the first and third ports 21 and 23 can communicate with each other. As described above, when the three-way valve 1 is switched to the low pressure condition, the first relief valve 42 may suitably function, so that the liquid fuel pumped into the third external conduit 43A by the fuel pump 41 can be maintained in the first setting pressure. Conversely, when the three-way valve 1 is switched to the high pressure condition, the second relief valve 43 may suitably function, so that the liquid fuel pumped into the third external conduit 43A can be maintained in the second setting pressure.
Further, the three-way valve 1 can be switched between the low pressure condition and the high pressure condition during operation of the fuel-feeding system S.
As shown in
Further, as best shown in
As shown in
Further, as shown in
Next, operation of the fuel-feeding system S will be described in detail.
When the magnetic coil 11 of the magnetic actuator portion 10 is actuated based on a signal from the control unit, the valve unit V of the three-way valve 1 is closed as described above (
Conversely, when the magnetic coil 11 of the magnetic actuator portion 10 is deactuated based on the signal from the control unit, the valve unit V of the three-way valve 1 is opened as described above (
According to the fuel-feeding system S thus constructed, the liquid fuel can be fed into the third external conduit 43A (the delivery tube 44A) at the first setting pressure or the second setting pressure by simply switching the three-way valve 1 between the first (low) pressure condition and the second (high) pressure condition. Also, the pressure of the liquid fuel fed into the third external conduit 43A can be accurately set to the first setting pressure or the second setting pressure by means of the first and second relief valves 42 and 43.
Further, in the fuel-feeding system S using the three-way valve 1, as shown by bold arrows in
Further, in order to increase cooling performance of the three-way valve 1, the connecting plate 13 may preferably be formed from a material having an excellent heat conductivity. Also, the connecting plate 13 can be treated so as to have an uneven surface, thereby increasing an area of contact with the liquid fuel. In such a case, the connecting plate 13 may preferably be treated so as to effectively prevent from producing turbulence in the fuel when the fuel pump 41 is actuated.
Further, in order to increase cooling performance of the three-way valve 1, the valve body portion 20 can be formed from a material having an excellent heat conductivity. In addition, cooling fins can be additionally formed in the valve body portion 20.
Naturally, various changes and modifications may be made to the three-way valve 1 of the fuel-feeding system S. For example, the arrangement of the first to third ports 21, 22 and 23 and the valve unit V can be changed, if necessary.
A representative example of the present invention has been described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present invention and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the foregoing detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe detailed representative examples of the invention. Moreover, the various features taught in this specification may be combined in ways that are not specifically enumerated in order to obtain additional useful embodiments of the present invention.
Number | Date | Country | Kind |
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2007-301628 | Nov 2007 | JP | national |