JP5325043B2 - Fuel supply device - Google Patents

Description

  The present invention relates to a fuel supply device that transfers fuel from a sub tank to a main tank and supplies fuel from the main tank to an engine.

  Conventionally, a four-wheel drive vehicle or the like employs a vertical fuel tank in which a main tank and a sub tank are arranged with a tank flange having a bottom surface raised upward to avoid interference with a propeller shaft and an exhaust pipe. In such vertical fuel tanks, it is necessary to transfer fuel from one tank to the other, and the fuel between the tanks can be obtained by using a negative-pressure jet pump or by using an electric pump that drives the jet pump. We are transporting.

  However, under low temperature conditions, the viscosity of the fuel increases, so that the required soot transfer performance may not be obtained. Especially in the case of diesel engine cars, the viscosity change accompanying the temperature change of light oil is larger than gasoline, compared to gasoline engine cars, so it is more strongly affected by temperature and is discharged even when using an electric pump as a transfer pump. There is a risk that the amount will be insufficient.

  For this reason, in Patent Document 1, the first and second chambers are provided in the main tank, and the suction port of the delivery passage for sending fuel to the engine and the fuel sucked from the main tank are passed through the sub tank. The discharge port of the soot transfer passage for transferring to the main tank is surrounded by the first chamber, and the discharge port of the return passage for introducing the return fuel from the engine to the main tank and the suction port of the soot transfer passage are surrounded by the second chamber. A vertical fuel tank having a configuration is disclosed.

  In the vertical fuel tank of Patent Document 1, the return fuel having a high temperature is returned into the second chamber to heat the fuel in the second chamber, and the heated fuel having a reduced viscosity is sucked by the transfer pump. As a result, the discharge amount of the transfer pump can be increased.

JP 2008-232088

  However, in the technique of Patent Document 1, although the fuel sucked by the transfer pump is heated to increase the discharge amount, the return fuel from the engine is mixed with the fuel in the second chamber and then sucked by the transfer pump. When the temperature is low, the temperature of the fuel sucked by the transfer pump is lowered, and the effect of increasing the discharge amount is reduced.

  In particular, when the engine is started at a low temperature, even if an electric transfer pump is used to drive the jet pump, the driving voltage decreases, so that the discharge due to the decrease in pump driving force in addition to the increase in fuel viscosity. A decrease in performance occurs, and the fuel transfer performance between tanks decreases accordingly.

  The present invention has been made in view of the above circumstances, and provides a fuel supply device capable of quickly increasing the temperature of fuel transferred from a sub tank to a main tank even under low temperature conditions and ensuring stable fuel transfer. The purpose is to do.

  To achieve the above object, a fuel supply apparatus according to the present invention comprises a fuel tank comprising a main tank and a sub tank, and a fuel supply apparatus having a transfer passage for transferring fuel from the sub tank to the main tank. A chamber surrounding the suction port of the delivery passage for delivering fuel to the engine and the discharge port of the transfer passage, and a chamber passage communicating with the return passage for returning the fuel from the engine. A transfer pump that sucks fuel from the junction of the return passage and the chamber passage and delivers the fuel to the discharge port of the transfer passage; and the transfer pump and the discharge passage discharge port having a suction port in the sub tank And a suction passage connected to the transfer passage.

  According to the present invention, the temperature of the fuel transferred from the sub tank to the main tank can be increased at an early stage even under low temperature conditions, and stable fuel transfer can be ensured.

Explanatory drawing showing the configuration of the fuel supply device

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a fuel tank that stores fuel to be supplied to an engine (not shown), and stores, for example, light oil that is fuel of a diesel engine. The fuel tank 1 is configured as a vertical fuel tank in which a main tank 3 and a sub-tank 4 are disposed with a tank flange 2 having a substantially centered bottom surface sandwiched, and a filler pipe 5 for refueling is disposed in the main tank 3. Has been.

  In the main tank 3, a cylindrical chamber 6 having a fuel supply port 6a communicating with the bottom of the main tank 3 at the bottom and an opening 6b at the top is provided. At the bottom of the chamber 6, there is a filter 11 communicated with the suction port of the fuel pump 14 via the delivery passage 12, and a soot transfer passage 24 for transferring fuel between the sub tank 4 and the main tank 3. A filter 21 communicated with the suction port of the transfer pump 23 through a part of the chamber passage 22 is disposed.

  Note that the filter 21 may be disposed in the vicinity of the suction side of the transfer pump 23 as indicated by a one-dot chain line in FIG.

  In the middle of the delivery passage 12, a filter 13 for removing impurities mixed in the fuel is interposed. The fuel in the chamber 6 is sucked by the fuel pump 14 via the filter 11 serving as the suction port of the delivery passage 12, the delivery passage 12, and the filter 13, and a part of the fuel reaching the fuel pump 14 is pumped from the discharge port. Then, it is supplied to each cylinder of an engine (not shown).

  The chamber passage 22 extends above the main tank 3 and is joined via a return passage 15 for returning surplus fuel in the fuel pump 14 and the three-way joint 16 to the suction port of the transfer pump 23. It is communicated. The fuel returned from the engine side via the return passage 15 is mixed with the fuel in the chamber 6 via the chamber passage 22 and sucked into the transfer pump 23, or surplus beyond the capacity of the transfer pump 23. The remaining portion is returned into the chamber 6 through the chamber passage 22.

  On the other hand, a soot transfer passage 24 that opens a discharge port 24 a in the chamber 6 of the main tank 3 is connected to the discharge port of the transfer pump 23. A suction passage 26 extending from a filter 25 that forms a suction port at the bottom of the sub-tank 4 is joined to the soot transfer passage 24 in the chamber 6. The joint 24b between the soot transfer passage 24 and the suction passage 26 sucks the fuel in the sub tank 4 by the negative pressure of the fuel that is pumped from the transfer pump 23 and passes through the joint 24b, and the fuel that is pumped from the transfer pump 23. At the same time, a jet pump is formed to be transferred into the chamber 6.

  The transfer pump 23 is constituted by an electric pump, functions stably without being affected by the operation region of the engine, that is, the operation state, and can secure a predetermined fuel flow rate in the soot transfer passage 24. Further, the jet pump formed by the joint portion 24b between the soot transfer passage 24 and the suction passage 26 may be installed on the sub tank 4 side.

  In the fuel supply device having the above-described configuration, the chamber passage joined by the single chamber 6 in the main tank 3 with the suction port (filter 11) of the delivery passage 12, the discharge port of the soot transfer passage 24, and the return passage 15. 22, the fuel heated by the engine is directly supplied to the suction side of the transfer pump 23. As a result, the temperature of the transferred fuel between the sub tank 4 and the main tank 3 can be raised at an early stage even under a low temperature condition, and a decrease in the discharge amount of the transfer pump 23 can be prevented to ensure stable fuel transfer. be able to. Next, the operation of fuel transfer between the sub tank 4 and the main tank 3 in the fuel supply apparatus will be described.

  When the fuel in the chamber 6 in the main tank 3 is pumped to the engine by the fuel pump 14, the surplus fuel is returned through the return passage 15. This return fuel depends on the relationship between the return flow rate and the soot transfer flow rate through the soot transfer passage 24 (the discharge flow rate of the transfer pump 23), or the suction port direction of the transfer pump 23 or the suction port direction of the transfer pump 23 and the main flow rate. It flows both in the direction of the chamber 6 of the tank 3.

  Here, assuming that the return flow rate is Q1 and the soot transfer flow rate is Q2, when Q1 <Q2 and the return fuel is low, the return fuel via the return passage 15 and the fuel in the chamber 6 of the main tank 3 via the chamber passage 22 Are mixed at the junction of the three-way joint 16 and sucked by the transfer pump 23.

  The fuel sucked by the transfer pump 23 is discharged into the soot transfer passage 24 and discharged into the chamber 6 from the discharge port 24a. At this time, the fuel in the sub tank 4 is sucked through the filter 25 and the suction passage 26 by the negative pressure of the fuel passing through the joint 24b between the soot transfer passage 24 and the suction passage 26, and is transferred into the chamber 6. .

  On the other hand, when Q1> Q2 and the amount of return fuel is large, a part of the return fuel that has passed through the return passage 15 is sucked into the transfer pump 23 and the surplus is discharged into the chamber 6 through the chamber passage 22. Is done. When Q1 = Q2, the entire amount of return fuel is sucked into the transfer pump 23, and the fuel flow in the chamber passage 22 is stopped.

  Thus, when the temperature is low, the hot and low-viscosity return fuel from the engine can be supplied to the suction side of the transfer pump 23, and the fuel sucked by the transfer pump 23 by mixing the return fuel with the fuel in the chamber as in the prior art. The temperature of the fuel flowing through the transfer pump 23 can be increased as compared with the conventional case.

  For example, in a common rail type diesel engine, the temperature of the return fuel from the engine immediately rises with respect to the fuel in the tank (for example, it becomes higher by about 15 ° C.). By supplying the fuel that has been heated much more than the fuel in the tank to the suction side of the transfer pump 23, the pump discharge amount of the transfer pump 23 can be increased, resulting in a shortage of the pump discharge amount even at low temperatures. Absent.

  In addition, by supplying the return fuel from the engine side upstream of the transfer pump 23, the return back pressure can be reduced, the suction load of the transfer pump 23 is reduced, and the pump discharge amount is reduced while saving power. Can be increased. In addition, since the return fuel heated by the engine flows through the soot transfer passage 24 via the transfer pump 23, the amount of fuel suction from the sub tank 4 via the suction passage 26 can be secured at the joint portion 24b. The fuel in the sub tank 4 can be transferred to the main tank 3 in a stable state.

  In particular, the temperature of the fuel flowing from the transfer pump 23 to the soot transfer passage 24 is increased at an early stage even when starting the engine under a low temperature condition in which the viscosity of the fuel increases and the drive voltage of the transfer pump 23 decreases. The suction load of the transfer pump 23 can be reduced, and stable soot transfer performance can be ensured regardless of the decrease in pump drive voltage.

  Further, unlike the conventional case, there is no need to provide a plurality of chambers such as a chamber for supplying fuel to the engine and a chamber for returning return fuel from the engine in the main tank. Can be abolished to simplify the pipeline structure.

  In the above embodiment, the fuel supply device for a diesel engine has been described as an example. However, the present invention may be applied to a fuel supply device for a gasoline engine, particularly a fuel supply device for an in-cylinder fuel injection type gasoline engine. An effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Tank saddle part 3 Main tank 4 Sub tank 6 Chamber 12 Delivery path 15 Return path 16 Three-way joint (merging part)
22 Chamber passage 23 Transfer pump 24 Firewood transfer passage 26 Suction passage

Claims (3)

In a fuel supply device having a fuel tank composed of a main tank and a sub tank, a transfer passage for transferring fuel from the sub tank to the main tank,
A chamber provided in the main tank and surrounding a suction port of a delivery passage for sending fuel to the engine and a discharge port of the transfer passage;
A chamber passage communicated with the chamber and joined with a return passage for returning fuel from the engine;
A transfer pump that sucks fuel from a junction between the return passage and the chamber passage and delivers the fuel to a discharge port of the transfer passage;
A fuel supply device comprising: a suction passage in the sub-tank that is connected to the transfer passage between the transfer pump and a discharge port of the transfer passage. 2. The fuel supply apparatus according to claim 1, wherein the fuel tank is a vertical fuel tank in which the main tank and the sub tank are arranged with a flange having a substantially centered bottom surface interposed therebetween.   The fuel supply device according to claim 1 or 2, wherein the engine is a diesel engine, and the fuel is diesel fuel.

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