JP2005351144A - Fuel supply system of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the pulsation of fuel pressure by minimizing the pressure loss with a simple structure in a fuel supply system of an engine. <P>SOLUTION: Since a relief valve 24 as a flow regulating valve capable of regulating the fuel flow rate is arranged in a feed pipe 20 between a filter 19 connected to a fuel pump 23, and a delivery pipe 21 connected to an injector 22, when the fuel pressure pulsates resulting that fuel liquid column of the feed pipe 20 between the filter 19 and the delivery pipe 21 resonates in the low rotational speed range of the engine, the pulsation of the fuel pressure can be reduced by the pressure loss generated in the relief valve 24. The opening of the relief valve 24 is increased in the high-speed range of the engine in which the fuel liquid column does not resonate so that the pulsation prevention of the fuel pressure and the pressure loss can be compatible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine fuel supply device that supplies fuel in a fuel tank to an injector via a fuel pump, a filter, and a delivery pipe.

A branch point connected to the high pressure regulator is formed in the middle of the high pressure fuel discharge passage connecting the high pressure pump for supplying fuel to the engine at a high pressure and a delivery pipe provided with a plurality of injectors. Patent Document 1 listed below discloses a damper (pulsation damper), a fixed orifice provided between the branch point and the delivery pipe, and a fuel pressure pulsation absorbed by the high pressure damper and the fixed orifice.
JP 2001-55961 A

  However, the above-mentioned conventional one has a problem that not only the structure of the high-pressure damper is complicated and causes an increase in cost, but also the layout in a narrow engine room becomes difficult due to its large size. In addition, the fixed orifice is small and low in cost, but there is a problem that pressure loss occurs when the fuel passes, and there is a problem that the pressure loss becomes large especially at high speed rotation of the engine where the amount of fuel supply increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce fuel pressure pulsation while minimizing pressure loss with a simple structure.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel supply apparatus for an engine that supplies fuel in a fuel tank to an injector via a fuel pump, a filter, and a delivery pipe. A fuel supply device for an engine is proposed in which a flow rate adjustment valve capable of adjusting the flow rate of fuel is arranged between pipes.

  According to the invention described in claim 2, in addition to the configuration of claim 1, the flow rate adjusting valve is opened when a predetermined valve opening pressure is applied, and the filter side to the delivery pipe side are opened. A fuel supply apparatus for an engine is proposed, which is constituted by a relief valve that allows fuel movement and prevents fuel movement in the opposite direction.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, the flow rate adjusting valve is opened when a predetermined valve opening pressure is applied, and from the filter side to the delivery pipe side. A first relief valve that allows fuel movement and prevents fuel movement in the opposite direction, and opens when a predetermined valve opening pressure is applied, allowing fuel movement from the delivery pipe side to the filter side Then, a fuel supply device for an engine is proposed in which the second relief valve for preventing the movement of fuel in the opposite direction is arranged in parallel.

  According to the invention described in claim 4, in addition to the structure of claim 1, the flow rate adjusting valve is integrated with a joint of a feed pipe for supplying fuel from a fuel tank or a fuel pump module. A featured fuel supply device is proposed.

  The relief valve 24 (first relief valve 24) and the second relief valve 24 'of the embodiment correspond to the flow rate adjusting valve of the present invention.

  According to the first aspect of the present invention, since the flow rate adjusting valve capable of adjusting the flow rate of the fuel is disposed between the filter connected to the fuel pump and the delivery pipe connected to the injector, the fuel liquid column between the filter and the delivery pipe is arranged. When the fuel pressure pulsates due to resonance at a predetermined engine speed, the pulsation of the fuel pressure can be reduced by the pressure loss generated in the flow regulating valve. Further, at the engine speed at which the fuel liquid column does not resonate, the pressure loss can be reduced by increasing the opening of the flow rate adjusting valve, so that both the prevention of pulsation of fuel pressure and the reduction of pressure loss can be achieved.

  According to the configuration of the second aspect, since the flow rate adjusting valve is constituted by a relief valve that only allows the movement of fuel from the filter side to the delivery pipe side, the pulsation of the fuel pressure can be achieved by changing the valve opening pressure of the relief valve. The prevention effect can be easily tuned.

  According to the configuration of the third aspect, the first relief valve that allows only the movement of the fuel from the filter side to the delivery pipe side of the flow rate adjusting valve, and the first relief valve that allows only the movement of the fuel from the delivery pipe side to the filter side. Since the two relief valves are arranged in parallel, the pulsation preventing effect of the fuel pressure can be easily tuned by changing the valve opening pressures of the first and second relief valves. Moreover, by providing the first and second relief valves, it is possible to further increase the pulsation preventing effect by generating pressure loss when the fuel moves in both directions.

  According to the configuration of the fourth aspect, since the flow rate adjusting valve is integrated with the joint of the feed pipe for supplying the fuel from the fuel tank or the fuel pump module, it contributes to the reduction of the number of parts and the number of assembling steps. it can.

  Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.

  1 to 5 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of an engine fuel supply apparatus according to a first embodiment. FIG. 2 shows a structure of a flow control valve according to a second embodiment. FIG. 3 is a graph showing the relationship between camshaft rotation speed and fuel pressure fluctuation amount, FIG. 4 is a graph showing the relationship between crankshaft rotation speed and average fuel pressure, and FIG. 5 is a graph showing the relationship between crank angle and fuel pressure. It is a graph which shows a relationship.

  As shown in FIG. 1, a fuel tank T for an automobile includes a tank body 11 for storing fuel and a filler pipe 12 for supplying fuel to the tank body 11. A recess 15 formed in the body 13 of the automobile and opened and closed by a lid 14 is provided with an oil filler port 16 connected to the upper end of the filler pipe 12, and the open end of the oil filler port 16 can be closed with a cap 17. . Inside the tank body 11, there is provided a fuel pump 23 that supplies the fuel pumped up through the strainer 18 to the injectors 22 of the engine E through the filter 19, the pressure regulator 28, the feed pipe 20 and the delivery pipe 21.

  By returning the surplus fuel to the tank body 11 via the pressure regulator 28, there is no return pipe for returning surplus fuel from the delivery pipe 21 to the fuel tank T, and this fuel supply device has a return pipe. It has a so-called returnless system.

  In the middle of the feed pipe 20 connecting the filter 19 and the delivery pipe 21, a relief valve 24 constituting the flow control valve of the present invention is arranged. The relief valve 24 accommodates a spherical valve body 26 inside a valve housing 25 having a valve seat 25a, and urges the valve body 26 in a direction to be seated on the valve seat 25a by a valve spring 27. When the pressure on the filter 19 side exceeds the pressure on the delivery pipe 21 and exceeds a predetermined valve opening pressure, the valve opens, allowing fuel to move from the filter 19 side to the delivery pipe 21 side, and fuel in the opposite direction. It is designed to prevent movement.

  FIG. 2 shows a second embodiment of the flow control valve of the present invention. A valve housing 25 'provided with a valve seat 25a' in the first relief valve 24 having the same structure as the relief valve 24 of the first embodiment. A second relief valve 24 'composed of a valve body 26' and a valve spring 27 'is arranged in parallel. The second relief valve 24 ′ is disposed in the opposite direction to the first relief valve 24 ′, and opens when the pressure on the delivery pipe 21 side exceeds a predetermined valve opening pressure than the pressure on the filter 19 side, The movement of the fuel from the delivery pipe 21 side to the filter 19 side is allowed, and the movement of the fuel in the opposite direction is prevented.

  Next, the operation of the embodiment having the above configuration will be described.

  When the injector 22 is opened and fuel injection is started, the fuel pressure in the delivery pipe 21 decreases, and the fuel pressure in the delivery pipe 21 increases rapidly at the moment when the fuel injection is finished and the injector 22 is closed. To do. The pressure wave generated at that time propagates in the feed pipe 20 toward the filter 19, and is phase-inverted at the opening end of the filter 19 and propagates in the feed pipe 20 toward the delivery pipe 21. 20 and the fuel pressure in the delivery pipe 21 pulsate at a predetermined cycle. When the fuel injection period of each injector 22 coincides with the pulsation period mainly at the time of low speed rotation such as when the engine E is started or idling, the fuel liquid column in the feed pipe 20 resonates and the fuel pressure varies. This may increase the adverse effect of controlling the fuel injection amount from the injector 22.

  In the case where the fixed orifice and the relief valve are not provided, as shown by the one-dot chain line in FIG. 3, the fluctuation amount of the fuel pressure rapidly increases due to the resonance phenomenon in the starting rotation range where the camshaft rotational speed is 0 to 350 rpm. I understand.

  In contrast, in this embodiment, when the fuel pressure fluctuates, a slight pressure loss is generated in the fuel passing through the relief valves 24, 24 'having a predetermined valve opening pressure, thereby preventing the resonance phenomenon from occurring. Pressure pulsation can be avoided.

  In the second embodiment in which the first relief valve 24 and the second relief valve 24 ′ are arranged in parallel and in opposite directions, the fuel can be moved in both directions, but the first relief valve 24 having only one relief valve 24 is provided. In one embodiment, when the injector 22 is closed and the fuel pressure in the feed pipe 20 on the delivery pipe 21 side is shockedly increased, the valve body 26 colliding with the valve seat 25a of the relief valve 24 rebounds, When the valve body 26 is seated on the valve seat 25a again by the resilient force of the valve spring 27, the relief valve 24 is opened and closed in a vibrational manner, and the movement of fuel from the delivery pipe 21 side to the filter 19 side is permitted. .

  Thus, compared with the first embodiment having only one relief valve 24, the second embodiment having two first and second relief valves 24, 24 'is bi-directional of fuel. Therefore, as is clear from FIG. 3, the pressure fluctuation is smaller in the second embodiment shown by the broken line than in the first embodiment shown by the solid line.

  As indicated by the one-dot chain line in FIG. 4, the average fuel pressure is maintained substantially constant even when the crankshaft rotational speed (engine rotational speed) is increased in the case without the fixed orifice or the relief valve. On the other hand, in the case where the fixed orifice indicated by the two-dot chain line is provided, the average fuel pressure rapidly decreases as the crankshaft rotational speed increases, and a large pressure loss is generated by the fixed orifice. Understand.

  In the first embodiment having only one relief valve 24 (see the solid line), the average fuel pressure is slightly reduced as compared with the one having no fixed orifice or relief valve, but the average fuel pressure is determined by the rotation of the crankshaft. Even if the number increases, it remains almost constant. Further, in the second embodiment (see the broken line) provided with the two first and second relief valves 24, 24 ', the average fuel pressure gradually decreases as the crankshaft rotational speed increases. Is equivalent to the first embodiment, and it can be seen that the pressure loss is smaller than that of the first embodiment.

  As shown by the one-dot chain line in FIG. 5, the fuel pressure pulsates greatly with the change of the crank angle in the case without the fixed orifice or the relief valve. As shown by the broken line, it can be seen that the pulsation of the fuel pressure is greatly reduced in the second embodiment including the two first and second relief valves 24 and 24 '. Even in the first embodiment having only one relief valve 24, the same pulsation reducing effect can be achieved.

  As described above, an extremely simple and low-cost structure in which the relief valve 24 (24 ') is disposed between the filter 19 and the delivery pipe 21, and the pulsation of fuel pressure generated particularly when the engine E rotates at a low speed is reduced. This makes it possible to stabilize the fuel injection amount from the injectors 22. In addition, the pressure loss can be suppressed to a minimum particularly when the engine E rotates at a high speed as compared with the case where the conventional fixed orifice is used. In addition, since the relief valve 24 (24 ') is employed as the flow rate adjusting valve, the valve opening pressure is adjusted by changing the spring constant of the valve spring 27 (27'), thereby easily reducing the pulsation effect of the fuel pressure. Can be tuned.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, although the relief valves 24 and 24 'are exemplified as the flow control valves in the embodiment, a check valve having a valve opening pressure of approximately 0 or a solenoid valve capable of electrically adjusting the opening degree can be employed. When a solenoid valve is used, the opening is reduced during low-speed rotation of the engine E, where fuel pressure pulsation is likely to occur, and the pressure loss is actively increased. If the pressure loss is reduced by increasing the degree, it is possible to more effectively achieve both pulsation prevention and pressure loss reduction.

  In the embodiment, the relief valves 24 and 24 'are arranged at the intermediate portion of the feed pipe 20. However, the relief valves 24 and 24' are arranged at any position between the filter 19 and the delivery pipe 21 regardless of the inside or outside of the fuel tank T. can do.

  The relief valves 24 and 24 'are integrated into the joint of the feed pipe 20, or the relief valves 24 and 24' are provided in a fuel pump module in which the strainer 18, fuel pump 23, filter 19, pressure regulator 28 and the like are modularized. They may be integrated, thereby reducing the number of parts and the number of assembling steps.

  Further, the relief valves 24 and 24 'are not limited to those using the spherical valve body 26, but can be of any structure, and any one of the first and second relief valves 24 and 24' can be adopted. May be constituted by an orifice.

1 is an overall configuration diagram of an engine fuel supply apparatus according to a first embodiment. The figure which shows the structure of the flow control valve which concerns on 2nd Example. Graph showing the relationship between camshaft rotation speed and fuel pressure fluctuation Graph showing the relationship between crankshaft speed and average fuel pressure Graph showing the relationship between crank angle and fuel pressure

Explanation of symbols

19 Filter 20 Feed pipe 21 Delivery pipe 22 Injector 23 Fuel pump 24 Relief valve, first relief valve (flow control valve)
24 'Second relief valve (flow adjustment valve)
T Fuel tank

Claims (4)

In an engine fuel supply device for supplying fuel in a fuel tank (T) to an injector (22) via a fuel pump (23), a filter (19) and a delivery pipe (21),
A fuel supply device for an engine, wherein a flow rate adjusting valve (24, 24 ') capable of adjusting a flow rate of fuel is disposed between the filter (19) and the delivery pipe (21).   The flow rate adjusting valve is opened when a predetermined valve opening pressure is applied to allow the fuel to move from the filter (19) side to the delivery pipe (21) side, and to prevent the fuel from moving in the opposite direction. The fuel supply device for an engine according to claim 1, characterized by comprising a relief valve (24).   The flow rate adjusting valve is opened when a predetermined valve opening pressure is applied to allow the fuel to move from the filter (19) side to the delivery pipe (21) side, and to prevent the fuel from moving in the opposite direction. A first relief valve (24) that opens and opens when a predetermined valve opening pressure is applied, allowing fuel to move from the delivery pipe (21) side to the filter (19) side, and fuel in the opposite direction The fuel supply apparatus for an engine according to claim 1, wherein the second relief valve (24 ') for preventing the movement of the engine is arranged in parallel. The flow rate adjusting valve (24, 24 ') is integrated with a joint of a feed pipe (20) for supplying fuel from a fuel tank (T) or a fuel pump module. Engine fuel supply device.

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