JP2016003621A - Common-rail fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a common-rail fuel injection system capable of suppressing a fall of a fuel pressure right after injection of fuel from an injector without incurring the degradation of assemblability and the risk of fuel leakage.SOLUTION: The present invention concerns a common-rail fuel injection system boosting a pressure of fuel and accumulating the fuel in a common rail 1 and introducing the fuel from the common rail 1 to an injector in a top portion of each cylinder. A coupling connector 7 attached to an opening portion of a fuel supply port to each injector in a cylinder head 3 so as to have a predetermined attachment attitude by being fastened in a plurality of portions and including two coupling ports 5 and 6 is provided, the coupling ports 5 or 6 of the respective coupling connector 7 are coupled by a first fuel injection pipe 8 to form a state of mutually communicating fuel supply systems to the respective injectors, and the remaining coupling ports 5 of the coupling connectors 7 on both ends in an alignment direction are coupled to the common rail 1 by a second fuel injection pipe 9 so as to be able to supply the fuel to each injector by using two systems.

Description

  The present invention relates to an accumulator fuel injection device.

  2. Description of the Related Art Conventionally, an accumulator type fuel injection device has been known as a method for increasing the injection pressure and optimally controlling the injection conditions such as the fuel injection timing and the injection amount in accordance with the operating state of the engine. In this type of accumulator fuel injection system, the high-pressure fuel is accumulated in the common rail by the high-pressure supply pump, and the high-pressure fuel accumulated in the common rail is individually directed to each injector installed in each cylinder of the engine. However, since the fuel pressure drops greatly immediately after the injector needle valve is opened at the time of injection, the average injection pressure during the fuel injection period decreases and the spray does not fly finely. The mixture of fuel and air in the interior deteriorates, so that black smoke is easily generated, fuel efficiency is deteriorated, and the fuel pressure immediately after injection is increased. Fatigue life of the injection material in accordance with pressure pulsation drop there is a problem to decrease in.

  Therefore, as a means for increasing the average injection pressure during the fuel injection period by suppressing the drop in fuel pressure immediately after injection in the injector, the injectors b are connected to each other by a fuel injection pipe c via a connection connector a as shown in FIG. Thus, the fuel supply system is in a state of communicating with each other, and a high pressure fuel is supplied from the common rail d via the two connecting connectors a at both ends in the arrangement direction. In this way, if high pressure fuel is supplied from the common rail d to each injector b in two systems, the drop in fuel pressure immediately after injection in each injector b can be suppressed, and the average during the fuel injection period can be reduced. The injection pressure can be increased.

JP 2013-79594 A

  However, in such a conventional structure, a connection connector a having a connection port e in three directions is used, and the fuel injection pipes c, f are connected between the connection connectors a, between the common rail d, and the injector b. , G, and it is necessary to adjust the direction of the connecting connector a in accordance with the direction of each fuel injection pipe c, f, g. In addition, there is a concern that fuel leakage may occur when the fuel injection pipes c, f, and g are fastened when the direction of the connecting connector a is poor. In addition, k in FIG. 5 shows the cylinder head which accommodates each injector b.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to realize an accumulator fuel injection device that can suppress a drop in fuel pressure immediately after injection in an injector without incurring the risk of assembly and deterioration of fuel leakage. And

  The present invention relates to a pressure accumulation type fuel injection apparatus in which fuel is boosted and stored in a common rail, and the fuel is guided from the common rail to an injector at the top of each cylinder and injected into each cylinder. A connecting connector having two connecting ports is provided so that a predetermined mounting posture is obtained by fastening a plurality of locations to the opening of the fuel supply port to the first connecting port. The fuel supply systems to each injector are connected to each other by one fuel injection pipe, and the connection ports that remain in the connection connectors at both ends in the arrangement direction are connected to the common rail by the second fuel injection pipe. Thus, the fuel can be supplied to each injector in two systems.

  Thus, in this way, as usual, high pressure fuel is supplied to each injector in two systems from the common rail to suppress the drop in fuel pressure immediately after injection in each injector, and the average injection pressure during the fuel injection period This makes it possible to finely fly the spray, thereby promoting the mixing of fuel and air in each cylinder, suppressing the generation of black smoke and avoiding the deterioration of fuel consumption. Furthermore, the pressure pulsation due to the drop in fuel pressure immediately after injection is alleviated, and the fatigue life of the injection system material is extended.

  In addition, when the connection connector is attached to the opening of each fuel supply port of the cylinder head, the connection connector becomes a predetermined attachment posture by fastening at a plurality of locations, and the directions of the two connection ports are always determined to be the same direction. Therefore, it does not take time and effort to adjust the direction of the connecting connector in accordance with the direction of each fuel injection pipe, the assembling property of each connecting connector is improved, and the risk of fuel leakage when the fuel injection pipe is fastened is reduced. .

  Further, in the present invention, the fuel inlet is opened at a position corresponding to the fuel supply port of the cylinder head on the side surface of the injector, and is inserted into the fuel supply port when the connecting connector is mounted, and the tip is on the side surface of the injector. It is preferable that a nozzle portion fitted and connected to the fuel inlet portion is provided on the back surface of the connection connector.

  In this case, when the nozzle part on the back surface of the connecting connector is inserted into the fuel supply port of the cylinder head and the connecting connector is attached, the tip of the nozzle part is attached to the fuel inlet part on the side of the injector simultaneously with the attachment of the connecting connector. Therefore, it is not necessary to perform a connection operation on the injector side, and a simple connection connector can be assembled.

  In the present invention, the gap between the outer peripheral surface of the nozzle portion of the connector and the inner peripheral surface of the fuel supply port is liquid-tightly sealed by the seal ring, and the gap sealed by the seal ring is the fuel return line. It is preferable to be configured so as to communicate with each other. In this case, even if fuel leaks from the connection portion between the tip of the nozzle portion of the connection connector and the fuel inlet portion of the injector, the fuel is returned to the fuel return line. It is possible to return the fuel tank to the fuel tank.

  According to the above-described pressure accumulation type fuel injection device of the present invention, the following various excellent effects can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the fuel supply system to each injector is in a state of communicating with each other, and fuel is supplied from the common rail to each injector via the connecting connectors at both ends in the arrangement direction. Supplying by the system to suppress the drop in fuel pressure immediately after injection, thereby promoting the mixing of fuel and air in each cylinder to suppress the generation of black smoke and avoid deterioration of fuel consumption, and to reduce pressure pulsation The fatigue life of the injection system material can be relaxed and can eliminate the trouble of adjusting the direction of each connecting connector and can avoid the deterioration of the assembling property of each connecting connector. The risk of fuel leakage can also be significantly reduced.

  (II) According to the invention described in claim 2 of the present invention, the tip of the nozzle portion can be fitted and connected to the fuel inlet portion on the side surface of the injector at the same time as the connection connector is mounted, and the connection work to the injector side is unnecessary. And simple assembly of the connector can be realized.

  (III) According to the invention described in claim 3 of the present invention, even if fuel leaks from the connecting portion between the tip of the nozzle portion of the connecting connector and the fuel inlet portion of the injector, the fuel is returned to the fuel return line. The fuel can be returned to the fuel tank and fuel leakage to the outside of the engine can be reliably prevented.

It is a perspective view which shows an example of the form which implements this invention. It is sectional drawing explaining the connection state of the connection connector of FIG. 1, and an injector. It is sectional drawing explaining the mounting state of the connection connector of FIG. It is the schematic which shows another form example of this invention. It is the schematic which shows a prior art example.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 show an example of an embodiment for carrying out the present invention. As in the case of the conventional example of FIG. 5 described above, the fuel is boosted and stored in the common rail 1, and each cylinder is supplied from the common rail 1 to each cylinder. The accumulator type fuel injection device is configured such that fuel is guided to the top injector 2 (see FIG. 2 and FIG. 3) and injected into each cylinder, but fuel supply to each injector 2 in the cylinder head 3 is achieved. A connection connector 7 provided with two connection ports 5 and 6 is provided so as to have a predetermined mounting posture by fastening a plurality of locations to the opening of the port 4 (see FIG. 3). One of the connection ports 5 or 6 is connected by a fuel injection pipe 8 (first fuel injection pipe) so that the fuel supply system to each injector 2 is in communication with each other, and the connection connectors 7 at both ends in the arrangement direction thereof. Left one by one The connection hole 5 is characterized by being configured so as to supply fuel in conjunction with the common rail 1 to each injector 2 by a fuel injection pipe 9 (second fuel injection pipe) in two systems.

  That is, in the example shown in FIG. 1, each connecting connector 7 is fastened to the left and right by bolts 10 so as to determine a predetermined mounting posture, and one connecting port 5 of each connecting connector 7 is laterally connected. 1 and the other connecting port 6 protrudes upward, and the upwardly connecting ports 6 in the first and second connecting connectors 7 from the left in FIG. The side connection ports 5 in the second and third connection connectors 7 and the upward connection ports 6 in the third and fourth connection connectors 7 are connected by a U-shaped fuel injection pipe 8 respectively. In addition, the side connection ports 5 in the first and fourth connection connectors 7 from the left in FIG. 1 are connected to the longitudinal ends of the common rail 1 by U-shaped fuel injection pipes 9, respectively. ing.

  Further, as shown in FIG. 2, a fuel inlet portion 13 forming a female tapered seat surface is opened at a position corresponding to the fuel supply port 4 of the cylinder head 3 on the side surface of the injector 2. On the back side, a nozzle having a male taper shape is inserted into the fuel supply port 4 when the connecting connector 7 is mounted, and the tip is fitted and connected to the tapered seating surface of the fuel inlet portion 13. A portion 14 is provided.

  Here, the fuel injection mechanism of the injector 2 is as shown in FIG. 2, and when the solenoid 15 is in a non-excited state and the valve body 16 is closed by the elastic force of the spring 17, the pressure accumulating chamber 18 becomes the fuel. The piston 19 is lowered to the lowest position by being held in a predetermined pressurized state by the fuel from the inlet portion 13, and the needle 20 is pushed to the lowest position where the injection port 21 can be closed by the piston 19. Yes.

  When the solenoid 15 is energized by energization to open the valve body 16, the fuel in the pressure accumulating chamber 18 is released to the outside of the injector 2 through the relief port 22, and the pressure accumulating chamber 23 to which pressure from the common rail 1 side is applied, The pressure balance with the pressure accumulating chamber 18 is lost, the pressing by the piston 19 is released, the needle 20 rises against the resilience of the spring 24, the injection port 21 opens, and the fuel is injected from the injection port 21 vigorously. Will be.

  Here, the fuel released from the relief port 22 to the outside of the injector 2 is extracted to the fuel return line 25 and returned to the fuel tank (not shown). A gap between the outer peripheral surface and the inner peripheral surface of the fuel supply port 4 is liquid-tightly sealed by the seal ring 26, and the gap sealed by the seal ring 26 communicates with the fuel return line 25. Yes.

  Thus, in this way, as before, high pressure fuel is supplied from the common rail 1 to each injector 2 in two systems to suppress the drop in fuel pressure immediately after injection in each injector 2, and during the fuel injection period Since it is possible to increase the average injection pressure and finely fly the spray, this promotes the mixing of fuel and air in each cylinder, thereby suppressing the generation of black smoke and avoiding deterioration of fuel consumption. Furthermore, the pressure pulsation due to the drop in fuel pressure immediately after injection is alleviated, and the fatigue life of the injection system material is extended.

  Moreover, when the connection connector 7 is attached to the opening of each fuel supply port 4 of the cylinder head 3, the connection connector 7 becomes a predetermined attachment posture by fastening a plurality of locations, and the two connection ports 5, 6 are connected. Since the direction is always determined to be the same direction, the trouble of adjusting the direction of the connection connector 7 in accordance with the direction of the fuel injection pipes 8 and 9 is eliminated, and the assembly property of each connection connector 7 is improved and fuel injection is performed. The risk of fuel leakage when the pipes 8 and 9 are fastened is reduced.

  Therefore, according to the above embodiment, the fuel supply systems to the injectors 2 are in communication with each other and connected to the connecting connectors 7 at both ends in the arrangement direction with the common rail 1 via the fuel injection pipes 9. Supplying fuel to the injector 2 in two systems to suppress the drop in fuel pressure immediately after injection, thereby promoting the mixing of fuel and air in each cylinder to suppress the generation of black smoke and avoid deterioration of fuel consumption In addition, the pressure pulsation can be eased and the fatigue life of the injection system material can be lengthened, and the trouble of adjusting the direction of each connecting connector 7 can be made unnecessary. Deterioration can be avoided, and the risk of fuel leakage can be significantly reduced.

  Particularly in this embodiment, when the nozzle portion 14 on the back surface of the connecting connector 7 is inserted into the fuel supply port 4 of the cylinder head 3 and the connecting connector 7 is attached, the nozzle portion 14 is simultaneously installed with the connecting connector 7. Since the tip of this is fitted and connected to the fuel inlet 13 on the side surface of the injector 2, it is possible to eliminate the need for connecting work to the injector 2 side, and to achieve simple assembly of the connecting connector 7. Even if the fuel leaks from the connection portion between the tip of the nozzle portion 14 of the connecting connector 7 and the fuel inlet portion 13 of the injector 2, the fuel can be returned to the fuel tank (not shown) through the fuel return line 25. As a result, fuel leakage to the outside of the engine can be reliably prevented.

  Here, in the embodiment shown in FIGS. 1 to 3, the case of four cylinders is illustrated, but of course, the present invention can be similarly applied to an engine having a number of cylinders other than four cylinders, for example, as shown in FIG. 4. The present invention can be applied to such an eight-cylinder engine without any problem. For such an engine having a relatively large number of cylinders, the connecting connectors 7 are assembled into a plurality of groups (two groups in the illustrated example) as shown in the figure. It is also possible to divide and connect the connecting connectors 7 at both ends in the direction of each group via the common rail 1 and the fuel injection pipe 9.

  In addition, the pressure accumulation type fuel injection device of the present invention is not limited to the above-described embodiment, and the direction of the connection port in each connection connector is not limited to the illustrated example, and does not depart from the gist of the present invention. Of course, various changes can be made within the range.

DESCRIPTION OF SYMBOLS 1 Common rail 2 Injector 3 Cylinder head 4 Fuel supply port 5 Connection port 6 Connection port 7 Connection connector 8 Fuel injection pipe (1st fuel injection pipe)
9 Fuel injection pipe (second fuel injection pipe)
13 Fuel Inlet Port 14 Nozzle Port 25 Fuel Return Line 26 Seal Ring

Claims (3)

  A pressure accumulation type fuel injection device that boosts fuel and stores it in a common rail, and directs the fuel from the common rail to an injector at the top of each cylinder and injects the fuel into each cylinder. Fuel supply to each injector in a cylinder head A connection connector having two connection ports, which is mounted so as to have a predetermined mounting posture by fastening at a plurality of positions with respect to the opening portion of the port, is provided, and a first fuel injection is made between one connection port of each connection connector Connected by pipes, the fuel supply system to each injector is in communication with each other, and the connection ports remaining one by one in the connecting connectors at both ends in the alignment direction are connected to the common rail by the second fuel injection pipes to each injector. An accumulator fuel injection device characterized in that fuel can be supplied in two systems.   A fuel inlet portion is opened at a position corresponding to the fuel supply port of the cylinder head on the side surface of the injector, and is inserted into the fuel supply port when the connecting connector is mounted, and the tip is inserted and connected to the fuel inlet portion on the side surface of the injector. The pressure accumulation type fuel injection device according to claim 1, wherein the nozzle portion is provided on a back surface of the connection connector.   A gap between the outer peripheral surface of the nozzle portion of the connecting connector and the inner peripheral surface of the fuel supply port is sealed in a liquid-tight manner by a seal ring, and the gap sealed by the seal ring is configured to communicate with the fuel return line. The pressure accumulation type fuel injection device according to claim 1 or 2, wherein

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