JPH03117676A - Fuel injection device - Google Patents

Abstract

PURPOSE:To improve controllability of low pressure injection by a method wherein a boosting injector and a normal injector are mounted facing mating cylinders. CONSTITUTION:In a controller 32, during middle and high load running, fuel accumulated in an accumulator 27 is fed to a boosting injector 15 of each cylinder 11 by switching a switching valve 24 to form high pressure injection. Meanwhile, during low load running of an engine, the switching valve 24 is switched in a reverse direction, and fuel pressurized by a fuel injection pump 19 is fed to a normal injector 16 mounted to a boosting injector 15. This constitution selectively performs high pressure injection and normal injection by switching the different types of injection, and compensates controllability of high pressure injection for poorness by performing normal injection on the low speed side or during low load running.

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a fuel injection device, and in particular, the present invention relates to a fuel injection device, in which the pressure of fuel pressurized by a fuel injection pump is accumulated in an accumulator, and the pressure of the fuel accumulated in the accumulator is increased by a pressure increasing injector to be injected into a cylinder. The present invention relates to a fuel injection device that injects fuel at Summary of the Invention: A pressure booster injector and a normal injector are provided to inject fuel into the cylinders of a diesel engine, and the pressure booster injector supplies fuel accumulated in pressure by an accumulator, and the pressure booster injector supplies fuel accumulated in an accumulator, The fuel injection pump injects pressurized fuel, and when the load is high, a pressure booster injector performs high-pressure injection, and when the load is light, the fuel is injected by a normal injector. It is. In addition, a partition plate is provided in the accumulator connected to the pressure boosting injector for high-pressure injection, and one of the two compartments separated by this partition plate is pressurized by the fuel injection pump. In addition to supplying fuel, a pressure booster injector is connected to each compartment divided by a partition plate, and when the accumulator is partitioned by the partition plate, fuel is not supplied from the fuel injection pump to the part. Fuel is not supplied to the pressure boosting injector corresponding to the compartment, thereby performing a partial shutdown. BACKGROUND OF THE INVENTION A diesel engine uses a fuel injection pump to pressurize fuel, and supplies the pressurized fuel to a fuel injection nozzle so that the fuel is injected into a cylinder through the nozzle. The injected fuel spray is spontaneously ignited and combusted by the heat of the intake air, which has become hot due to compression. High-pressure injection has been proposed to reduce particulates and black smoke contained in the exhaust gas of such diesel engines. For example, 2000 to 3000
It attempts to inject fuel at a pressure of kg/c. If such high-pressure injection were to be performed using a conventional Bosch fuel injection pump, the frame would be large and
It becomes difficult to install it in the engine. Moreover, such a pump has a large driving torque, which causes a loss in engine output. Therefore, a unit injector type pressure booster injector has come to be used for such high pressure injection.

[Problems to be solved by the invention]

If fuel is injected using a pressure booster injector to perform high-pressure injection in order to improve exhaust gas, a problem arises in the stability of the engine at low speeds under light loads. That is, while conventional fuel injection pumps use a stroke control system, pressure booster injectors use electromagnetic valves to control the valve opening time, which has the drawback of being difficult to control. In addition, variations in control tend to occur, and there are problems with the operability of the N magnetic piece and the source pressure during cranking.
There are concerns about starting performance. Further, in such a high-pressure injection system, fuel pressurized by a fuel injection pump is stored in a -H accumulator, and the fuel is supplied from the accumulator to a pressure-increasing injector. Therefore, unlike conventional fuel injection pumps, there is a drawback that it is not possible to perform a partial shutdown by stopping the supply of fuel to some cylinders. The present invention has been made in view of these problems, and it is an object of the present invention to provide a fuel injection device that improves controllability during light loads and also allows partial shutdown as necessary. This is the purpose.

[Means to solve the problem]

A first aspect of the present invention provides a device for accumulating fuel pressurized by a fuel injection pump in an accumulator, increasing the pressure of the fuel accumulated in the accumulator by a pressure increasing injector, and injecting it into a cylinder. A normal injector is provided corresponding to each cylinder so as to be juxtaposed with a pressure injector, and the normal injector is connected to the fuel injection pump via a switching valve. A second aspect of the invention is a device in which fuel pressurized by a fuel injection pump is stored in an accumulator, and the pressure of the fuel stored in the accumulator is increased by a pressure increasing injector and injected into a cylinder. means is provided in the accumulator, the pressure boosting injector is connected to a portion of each compartment of the accumulator partitioned by the partitioning means, and one partition of the accumulator partitioned by the partitioning means and the fuel injection pump It is designed to connect.

[Effect]

Therefore, according to the first invention, by switching the switching valve, high pressure injection is performed by the pressure increasing injector through the accumulator, and when the engine is under a light load, by switching the switching valve to the opposite side, the fuel injection pump It becomes possible to inject fuel by supplying pressurized fuel to a normal injector,
In particular, controllability under light loads can be improved. Further, in the second invention, when the accumulator is partitioned by the partition plate, fuel is supplied from the fuel injection pump only to one of the two partitions partitioned by the partition plate, and the pressure increase corresponding to this partition is Only the injectors will be supplied with fuel. Therefore, the fuel supply to the cylinder corresponding to the booster injector connected to the other compartment of the accumulator is cut off, resulting in a partial shutdown of the engine. K Embodiment FIG. 1 shows a diesel engine equipped with a fuel injection device according to a first embodiment of the present invention, and six cylinders 11 are formed in the cylinder block of this engine 10. . A piston 12 is slidably held in each cylinder 11, and the upper opening of the cylinder 11 is closed by a cylinder head 13. A pressure booster injector 15 and a normal injector 16 for injecting fuel into the combustion chamber 14 of the piston 12 are respectively attached to the cylinder head 13. Further, a fuel injection pump 19 is attached to the side of this diesel engine 10. The fuel injection pump 19 is provided with a camshaft 20, and a timer 21 is attached to this camshaft 20.
The timing of fuel injection is adjusted by In addition, the fuel injection pump 19 has a mechanical governor 2.
2 is attached, and the amount of fuel injected at one time is adjusted by this governor 22. Further, the discharge side of each pump unit of the fuel injection pump 19 is connected to a switching valve 24 via a connecting pipe 23. The switching valve 24 is equipped with two systems of outlet boats, and a filling pipe 25 and an injection pipe 26 are connected to each boat. The filling pipe 25 is adapted to be connected to an accumulator 27. This accumulator 27 is connected to the pressure increasing injector 15 via a solenoid valve 28 and an injection pipe 29. On the other hand, the injection pipe 26 is connected to a normal injector 15 attached to the cylinder head 13 corresponding to each cylinder 11. In order to control the switching valve 24 and the solenoid valve 28,
This engine 10 is provided with a controller 32. The input side of the controller 32 is connected to a rotation detection sensor 33 and a load sensor 34. The rotation detection sensor 33 is configured to detect the rotation speed of the engine 10, and the load sensor 34 is configured to detect the load on the engine 10. The controller 32 controls the electromagnetic valve 28 and a solenoid coil 35 that switches the switching valve 24. In the above configuration, this diesel engine 1
0, high pressure injection is performed by the pressure booster injector 15 when the load is high, whereas fuel is injected by the normal injector 16 when the load is light. The controller 32 reads the rotational speed and load of the engine 1o using the rotation detection sensor 33 and the load sensor 34, and when it is determined that the pressure increasing injector is used as shown in FIG. The switching valve 24 is switched to the filling pipe 25 side. Therefore, the fuel pressurized by the fuel injection pump 19 passes through the switching valve 24 and the filling pipe 25 to the accumulator 2.
7, and the fuel in the accumulator 27 is 200~
It will accumulate at a pressure of 300 kg/cm. Then, the solenoid valve 28 is controlled by the controller 32 at a predetermined timing. The solenoid valve 28 controls the injection timing and injection amount. Note that the injection amount is controlled by the time that the solenoid valve 28 is open. When the solenoid valve 28 is opened, the fuel stored in the accumulator 27 is supplied to the pressure boosting injector 15, and this injector 15 increases the pressure by 10 to 20 times to 2000 to 2000.
The pressure of the fuel is increased to 6000 kg/cm and is injected into the combustion chamber 14 formed at the top of the piston 12. Such a pressure booster injector 1
By injecting fuel at a very high pressure according to No. 5, it becomes possible to prevent the generation of particulates and black smoke in the exhaust gas, thereby making it possible to improve the exhaust gas. When the controller 32 determines based on the rotation detection sensor 33 and the load sensor 34 that the normal injector 16 is used, the solenoid coil 35 switches the switching valve 24 to the injection pipe 26 side, and the solenoid valve 28 is switched to the injection pipe 26 side. left in a closed state. Therefore, fuel pressurized by the fuel injection pump 19 is intermittently supplied to the normal injector 16 through the switching valve 24 and the injection pipe 26.
6 to normal pressure, i.e. 200-300 kg/
Fuel is injected at a pressure of cj. In this way, since the normal injector 16 is used to inject fuel during light loads, especially at low speeds, it becomes possible to directly control the fuel injection pump 19. Therefore, the use of the solenoid valve 28 is eliminated, making it possible to avoid deterioration of controllability due to malfunction of the solenoid valve 28 and problems with source pressure at startup, making it possible to stabilize control at light loads or at low speeds. It becomes possible to do so. FIG. 2 shows the pressure of fuel applied to the fuel injection nozzle and the concentration of exhaust gas, and as the injection pressure increases, the concentration of exhaust gas decreases. As shown in FIG. 3, the controller 32 switches between the pressure boosting injector 15 and the normal injector 16 depending on the operating state of the engine 10. Therefore, such an engine 10
According to this, as shown in FIG. 4, the injection pressure increases depending on the engine load, and the severity of smoke is reduced accordingly. Therefore, it is possible to simultaneously achieve improvements in exhaust gas caused by high-pressure injection and improvements in controllability caused by normal fuel injection in a low-speed range. Next, a second embodiment will be explained with reference to FIG. This second embodiment relates to a high-pressure injection type diesel engine capable of performing a partial shutdown, and each cylinder 11 of the engine 10 holds a piston 12, and the cylinder 1
1 is closed by a cylinder head 13. An injector 15 is attached to the cylinder head 3 so that the pressure increasing injector 15 injects fuel toward a combustion chamber 14 formed on the top surface of the piston 12. A fuel injection pump 19 is attached to the side surface of the cylinder block of the engine 10, and a timer 21 is attached to the camshaft 20 of this fuel injection pump 19 to adjust the timing of fuel injection. . Further, a mechanical governor 22 is provided on the pump 19 in order to adjust the fuel injection [1] by the fuel injection pump 19. Each pump unit of the fuel injection pump 19 is connected to an accumulator 27 via a filling pipe 25. The accumulator 27 is connected to the pressure increasing injector 15 via a solenoid valve 28 and an injection pipe 29. Moreover, the accumulator 27 is provided with a partition plate 37, and the inside of the accumulator 27 is divided into two parts by this partition plate 37.
It can be divided into two sections. A solenoid coil 38 is used to open and close the partition plate 37. This solenoid coil 38 is connected to the controller 32
It is now controlled by. controller 3
2 is also connected to a solenoid valve 28 that controls the supply of fuel to each booster injector 15. A rotation detection sensor 33 and a load sensor 34 are connected to the input side of the controller 32. These sensors 33 and 34 detect the rotation speed and load of the engine 10, respectively. In the above configuration, normally the accumulator 27
The partition plate 37 has moved upward, and the spaces before and after the accumulator 27 are in communication with each other. Therefore, the fuel pressurized by the fuel injection pump 19 is filled into the accumulator 27 through the filling pipe 25, and the pressure is accumulated. When the solenoid valve 28 is opened at a predetermined timing by the controller 32, the fuel pressure accumulated in the accumulator 27 is supplied to the pressure boosting injector 15 through the injection pipe 29, and the pressure boosting injector 15 supplies the fuel pressure accumulated in the accumulator 27 to the pressure boosting injector 15. Fuel will be injected toward the combustion chamber 14 at the top. As a result, normal operation of the diesel engine 10 is performed. Next, the solenoid coil 38 is controlled by the controller 32.
When the partition plate 37 is closed by operating the accumulator 27, the accumulator 27 is divided into two spaces, the front and the rear. Since the three pump units of the fuel injection pump 12 inject fuel only into the compartments on the front side of the partition plate 37 of the accumulator 27, the fuel does not flow into the compartments on the rear side of the partition plate 37. Pressure will no longer accumulate. Therefore, although fuel is injected into the front three cylinders of this engine 10 by the pressure booster injector 15, fuel is no longer injected into the rear three cylinders, resulting in a partial shutdown. That is, in a six-cylinder engine, fuel is injected only to the front three cylinders, and fuel is cut off to the rear three cylinders. For this reason, the previous 3
The ignition order is set so that operation is performed by injection in only the cylinders. Therefore, according to such an engine 1o, high pressure injection is performed by the accumulator 27 and the pressure boosting injector 15, and exhaust gas is improved. Furthermore, by partitioning the seven cumulators 27 with the partition plates 37 as necessary, it becomes possible to perform a partial shutdown, and it becomes possible to improve the startability of the engine 10 and the white smoke and odor at the time of starting.

【Effect of the invention】

As described above, in the first invention, a normal injector is provided corresponding to each cylinder so as to be juxtaposed with a pressure booster injector, and the normal injector is connected to a fuel injection pump via a switching valve. It is something. Therefore, it is possible to selectively perform high-pressure injection and normal injection, and by performing normal injection at low speeds or under light load, it is possible to compensate for poor controllability of high-pressure injection. Further, the second invention provides a partitioning means for the accumulator, and a pressure boosting injector is connected to each section of the accumulator partitioned by the partitioning means, and a fuel injection injector is connected to one section of the accumulator partitioned by the partitioning means. It is designed to be connected to a pump. Therefore, when the accumulator is divided into two sections by the partition means, fuel is no longer supplied to the booster injector corresponding to the section not connected to the fuel injection pump, resulting in a partial shutdown of the engine.

[Brief explanation of drawings]

Fig. 1 is a side view of a diesel engine having a fuel injection device according to a first embodiment of the present invention, Fig. 2 is a graph showing the relationship between fuel injection pressure and exhaust gas concentration, and Fig. 3 is a graph showing the relationship between fuel injection pressure and exhaust gas concentration. FIG. 4 is a graph showing the switching region, FIG. 4 is a graph showing injection pressure and smoke amount with respect to engine load, and FIG. 5 is a front view of a diesel engine equipped with a fuel injection device according to a second embodiment.・The names of the main parts in the drawing are as follows. 10... Diesel engine 11... Cylinder 14... Combustion chamber 15... Pressure booster injector 16... Normal injector 19... Fuel injection pump 24... Switching valve 27... Accumulator 28 ... Solenoid valve 37 ... Partition plate 38 ... Solenoid coil

Claims (1)

[Claims] 1. Fuel pressurized by a fuel injection pump is stored in an accumulator, and the pressure of the fuel stored in the accumulator is increased by a pressure boosting injector and injected into a cylinder. In the apparatus, a normal injector is provided corresponding to each cylinder so as to be juxtaposed with the pressure boosting injector, and the normal injector is connected to the fuel injection pump via a switching valve. Fuel injection device. 2. In an apparatus in which fuel pressurized by a fuel injection pump is stored in an accumulator, and the pressure of the fuel stored in the accumulator is increased by a pressure increasing injector and injected into a cylinder, the partition means is The pressure boosting injector is provided in an accumulator, and the pressure boosting injector is connected to each compartment of the accumulator partitioned by the partitioning means, and one partition of the accumulator partitioned by the partitioning unit is connected to the fuel injection pump. A fuel injection device characterized by: