JP2007170348A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate assembly and maintenance thereafter by making an arrangement position of a common rail in relation to an injector appropriate and make a connection direction of a fuel pipe appropriate. <P>SOLUTION: In this engine, the common rail 3 is arranged on an engine cover 2 above a cylinder head 1 along a longitudinal direction of the cylinder head 1, a delivery side fuel pipe connection port 4 of the common rail 3 is opened on an opposite side to the injector 5, and the fuel pipe 7 is bent upward from the delivery side fuel pipe connection port 4 and is connected to a supply side fuel pipe connection port 6 of the injector 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine equipped with a common rail.

  In an engine, a technique for saving fuel and reducing noise by supplying high-pressure fuel to each cylinder through a common rail and controlling the pressure of the common rail, that is, the fuel supply pressure and the injection timing of the injector has been widely used.

For example, Japanese Unexamined Patent Application Publication No. 2004-308512 discloses a fuel piping structure between a common rail and an injector in such an engine.
JP 2004-308512 A

  Patent Document 1 describes a piping structure in which all fuel pipes connecting the common rail and the injector are made equal in length, but the installation position of the common rail and the opening direction of the fuel pipe connection port are not appropriate. In addition, the fuel pipe is bent in a complicated manner, and the installation is troublesome and the maintainability is poor.

  Accordingly, an object of the present invention is to make assembly easy and facilitate subsequent maintenance by making the arrangement position of the common rail relative to the injector and making the connecting direction of the fuel pipes appropriate.

The above object of the present invention is achieved by the following configuration.
That is, according to the first aspect of the present invention, the common rail 3 is disposed along the longitudinal direction of the cylinder head 1 on the engine cover 2 above the cylinder head 1, and the discharge side fuel pipe connection port 4 of the common rail 3 is opposite to the injector 5. The engine is configured such that the fuel pipe 7 is connected to the supply side fuel pipe connection port 6 of the injector 5 by being bent upward from the discharge side fuel pipe connection port 4.

According to the first aspect of the present invention, when the fuel pipe 7 is connected to the discharge side fuel pipe connection port 4 of the common rail 3, it is performed from the side of the cylinder head 1.
In the invention of claim 2, the fuel rail (3) side fuel pipe connection port (10) of the fuel pipe (9) piped from the fuel pump (8) to the common rail (3) is connected to the discharge side fuel of the common rail (3). The engine according to claim 1, wherein the engine is provided in line with the pipe connection port (4).

  In the invention according to the second aspect, the fuel pipe 9 piped from the fuel pump 8 to the common rail 3 is arranged and fixed to the side portion of the cylinder head 1.

  According to the first aspect of the present invention, it is easy to attach the fuel pipe 7 to the common rail 3 because it is a side portion of the cylinder head 1, and the fuel pipe 7 is bent without difficulty to connect the fuel pipe 7 on the supply side of the common rail 3. Can be connected to the mouth 6. Moreover, by arranging the common rail 3 along the longitudinal direction of the cylinder head 1, the supply side fuel pipe connection port 6 and the supply side fuel pipe connection port 6 of the injector 5 are arranged in parallel, and the fuel pipes 7 intersect each other. No interference occurs between the fuel pipes 7 due to engine vibration.

  In the second aspect of the present invention, the fuel pipe 9 piped from the fuel pump 8 to the common rail 3 is a side portion of the cylinder head 1, so that the mounting is easy and the thermal influence of the engine is small.

FIG. 1 is an external perspective view showing an upper structure of a diesel engine that embodies the present invention.
The fuel pump 8 is attached to the upper and lower intermediate sides of the engine body 40, and the cylindrical monrail 4 is attached to the lower head cover 2a constituting the cylinder head cover 2 on the upper side of the engine body 40 along the longitudinal direction of the engine. The cylinder head cover 2 includes a lower head cover 2a that covers the entire cylinder head and an upper head cover 2b that covers the injector 5 so that the injector 5 can be removed. Since the upper head cover 2b has a shape that circumvents the injector 5 in a U-shape so that the injector 5 can be removed without removing the upper head cover 2b, maintenance can be performed easily.

  The injector 5 is attached to the cylinder head by being pressed by a clamp 39 in order to keep the injection port position in a predetermined direction. 2 and 3, the clamp 39 includes bifurcated push legs 42a and 42b that engage with the flange portion of the injector 5 and a single support leg 43. The lower end surface 46 of the push legs 42a and 42b is in the longitudinal direction. The lower end surface 45 of the support leg 43 is formed into a spherical shape, the upper end seating surface 44 of the bolt insertion hole 47 is recessed into a spherical shape, and a spherical washer 51 is applied to the upper end seating surface 44 to provide a bolt. Thus, the injector 5 is firmly pressed down at the three points of the bifurcated push legs 42a and 42b of the clamp 39 and the single support leg 43 without touching each other.

  FIG. 4 is a partial cross-sectional view showing the attachment of the injector 5 and the clamp 39. The injector 5 is fitted into the nozzle hole of the cylinder head 49 through the lower head cover 2a and pressed by the clamp 39. A bolt to be inserted into the bolt insertion hole 47 is screwed into a screw hole of the cylinder head 49, and a high rigidity boss 50 reaching the cylinder head 49 is inserted into the lower head cover 2a at a position where the support leg 43 of the clamp 39 abuts.

  The common rail 3 formed in a cylindrical shape is attached with the discharge-side fuel pipe connection port 4 and the supply-side fuel pipe connection port 10 facing outward along the recessed groove portion of the lower head cover 2a. Similarly, the supply side fuel pipe connection port 6 of the injector 5 is fixed outward, and the discharge side fuel pipe connection port 4 of the common rail 4 and the supply side fuel pipe connection port 6 of the injector 5 are connected by a fuel pipe 7. ing. The fuel pipe 7 is bent without difficulty so that each pipe has the same length. A fuel pipe 9 piped from the fuel pump 8 through the intake manifold 41 is connected to the supply side fuel pipe connection port 6 of the common rail 3. The fuel pipe 9 is fixed on the intake manifold 41 with a clamp 48.

The return pipe 20 from the injector 5 passes over the upper head cover 2 b and enters the fuel pump 8, and is further connected to the fuel tank 15.
An exhaust manifold 52 is arranged on the opposite side of the engine body from the intake manifold 41, and an EGR cooler 53 is attached to the lower part of the exhaust manifold 52 to balance the left and right.

  As shown in FIG. 6, the EGR cooler 53 and the EGR valve 54 are attached to the fuel pump 8 below the intake manifold 41 of the engine body 40, and the fuel filter 17 is attached to the lower side of the EGR cooler 53, The lower space of the intake manifold 41 may be used effectively so that various maintenance can be performed on one side of the engine body 40.

  FIG. 7 is a plan sectional view of the combustion chamber of the cylinder, and the peripheral wall has a hexagonal hole shape. 55 is an upper surface of the piston, and a raised portion 56 is formed at the center thereof, and six grooves 57 are provided in the raised portion 56 from the center toward the peripheral wall of the combustion chamber 54. The direction of each groove 57 has an angle θ slightly inclined from the orthogonal to the peripheral wall 59, and the mist fuel sprayed from the injection port of the injector 5 to the center of the raised portion 56 hits the peripheral wall 59 through the groove 57. It flows in one direction and rotates. Reference numeral 58 denotes an air inlet.

  Since the groove 57 of the raised portion 56 corresponds to the number of injection ports of the injector 5, there are six spray ports in this embodiment. With such a structure, the fuel is completely burned, and the generation of smoke and nitrogen oxides can be reduced.

Next, the fuel injection control state will be described with reference to the fuel supply system diagram shown in FIG.
The fuel in the fuel tank 15 is sucked into the fuel pump 8 driven by the engine through the fuel filter 17 through the suction passage 16, and the high-pressure fuel pressurized by the fuel pump 8 is guided to the common rail 3 through the discharge passage 18. Stored.

  The high-pressure fuel in the common rail 3 is supplied to the injectors 5 corresponding to the number of cylinders by the high-pressure fuel supply pipes 7, and the injectors 5 are opened for each cylinder based on a command from an engine control unit (hereinafter referred to as “ECU”) 19. In operation, high pressure fuel is injected into each cylinder combustion chamber of the engine.

  Excess fuel (return fuel) in each injector 5 is led to a common return pipe 21 by each return pipe 20, and returned to the fuel tank 15 by this return pipe 21.

  Further, a pressure control valve 22 is provided in the fuel pump 8 in order to control the fuel pressure in the common rail 3 (common rail pressure). This pressure control valve 22 adjusts the flow area of the return pipe 20 of the surplus fuel from the fuel pump 8 to the fuel tank 15 by the duty signal from the ECU 19, thereby adjusting the fuel discharge amount to the common rail 3 side. Thus, the common rail pressure can be controlled. Specifically, the target common rail pressure is set according to the engine operating conditions, and the common rail pressure is fed back via the pressure control valve 22 so that the common rail pressure detected by the common rail pressure sensor 23 matches the target common rail pressure. Control.

FIG. 9 is a signal input control block diagram of the ECU 18.
Engine speed sensor 24, cylinder discrimination sensor 25, accelerator pedal or accelerator lever opening sensor 26, intake air turbo pressure sensor 27, intake air temperature sensor 28, radiator water temperature sensor 29, intake air amount sensor 30, position of work lever Each information of the sensor 31, the common rail pressure sensor 23, and the timer 35 is input to the ECU 19, and a glow plug control signal 32, an injector control signal 33, and a common rail pressure control signal 34 are output from the ECU 19.

Next, the control state of this diesel engine is demonstrated using a data map and a flowchart.
In a diesel engine, it is known to perform a pilot injection that injects a small amount of fuel in a pulse manner prior to a main injection, thereby shortening an ignition delay and reducing a so-called knocking noise peculiar to a diesel engine.

  Conventionally, the pilot injection is fixed to be performed once or twice before the main injection, but in the embodiment of the present invention, this is changed according to the state of the engine, thereby reducing noise and incomplete combustion. The generation of white smoke and black smoke is suppressed.

  After the engine is started, pilot injection is controlled by a pilot injection control map showing the relationship between the engine speed and the fuel injection amount in FIG. There are one to three pilot injections, but a transition region is provided between each pilot frequency range to switch the pilot frequency by shifting the time for each cylinder.

  In the transition region, for example, in the case of a four cylinder engine, when switching from no pilot to one pilot as shown in FIG. By increasing the number of cylinders that perform pilot injection at regular intervals, a rapid increase in noise can be suppressed.

The start of pilot injection in this transition region may be started at equal intervals by two cylinders by igniting the ignition order or skipping one cylinder as shown in FIG.
The pilot injection pressure in this transition region is lower than the main injection pressure, but the pilot injection pressure is set to be high for the first time and low for the second time, or low for the first time and high for the second time. The first time and the second time can be set to the same pressure, and may be set appropriately.

  Diesel engines generate black smoke and increase noise during sudden acceleration, etc. To prevent this, the opening speed of the accelerator pedal is detected and the interval between the number of pilot injections and the main injection is changed. I am doing so.

  In the acceleration state as shown in FIG. 13, pilot injection control as shown in FIG. 14 is performed. In other words, the pilot injection is decreased and the pilot injection timing is shortened as the acceleration is accelerated from the rapid acceleration, and the pilot injection amount is increased.

  Conventionally, when the engine is lightly loaded, fuel injection is performed once every two cycles instead of every cycle, and the common rail pressure is reduced to reduce fuel consumption. To prevent this, exhaust gas and harmful gas were discharged. To prevent this, the common rail pressure remains high and the injection timing is set to once every four cycles, for example, to simplify the control and burn the fuel completely. I can do it.

  When the diesel engine is driven at an output of 90% or more, it becomes overheated, but the degree of overheating varies depending on the temperature of the intake air. That is, the higher the outside air temperature, the easier it is to overheat. Therefore, the correction maps of FIGS. 15 to 17 are used depending on the detected temperature of the intake air temperature sensor 28. That is, the injection amount is decreased as the intake air temperature rises in FIG. 15, the injection timing is changed from the retarded angle to the advanced angle as the intake air temperature rises in FIG. 16, and the common rail fuel is increased as the intake air temperature rises in FIG. The pressure is increased. This correction% is based on an intake air temperature of 0 ° C.

  Since the fact that the diesel engine has become overheated is also detected by the water temperature of the radiator, as shown in FIG. 18, when the water temperature detected by the radiator water temperature sensor 30 exceeds the normal temperature (80 ° C.), the injector 5 The injection timing is advanced than usual. Thereby, overheating of the engine can be prevented without reducing the output.

1 is an external perspective view of a diesel engine according to the present invention. It is a partially enlarged front view of the embodiment of the present invention. It is a partially expanded plan view of an embodiment of the present invention. It is a partially expanded cross-sectional perspective view of the Example of this invention. 1 is an overall rear view of an embodiment of the present invention. It is a front view of this invention Example. It is a partially expanded plan view of an embodiment of the present invention. It is a fuel supply system figure of an example of the present invention. It is a control block diagram of an embodiment of the present invention. It is a control map of the engine speed of this invention Example, and the number of times of pilot injection. It is a control map of the cylinder which performs engine speed of this invention Example and pilot injection. It is a control map of the cylinder which performs engine speed and pilot injection of another example. It is a rotation rise pattern figure of this invention Example. It is a pilot injection pattern figure at the time of a rotation rise of the example of the present invention. 4 is an intake air temperature and injection amount correction control map according to an embodiment of the present invention. It is an intake air temperature and injection timing correction control map of the Example of this invention. 4 is an intake air temperature and common rail pressure correction control map according to an embodiment of the present invention. It is time passage explanatory drawing of the intake air temperature of this invention Example, and injection timing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Engine cover 3 Common rail 4 Discharge side fuel pipe connection port 5 Injector 6 Supply side fuel pipe connection port 7 Fuel pipe 8 Fuel pump 9 Fuel pipe 10 Supply side fuel pipe connection port

Claims (2)

  A common rail (3) is arranged along the longitudinal direction of the cylinder head (1) on the engine cover (2) at the top of the cylinder head (1), and the discharge side fuel pipe connection port (4) of the common rail (3) is an injector. Open to the opposite side of (5), bend upward from the discharge side fuel pipe connection port (4) and connect the fuel pipe (7) to the supply side fuel pipe connection port (6) of the injector (5) The engine that becomes.   The common rail (3) side fuel pipe connection port (10) of the fuel pipe (9) piped from the fuel pump (8) to the common rail (3) is arranged side by side on the discharge side fuel pipe connection port (4) of the common rail (3). The engine according to claim 1.

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