JPS6016779Y2 - Fuel injection device for internal combustion engines - Google Patents

Description

[Detailed explanation of the idea] Industrial applications The present invention relates to a fuel injection device for an internal combustion engine.

Problems to be Solved by the Prior Art and Ideas There is a fuel injection device that includes an injector that is operated by pressurized oil from a pump driven by an engine.

In this type of device, a pressure accumulator is provided on the pressure oil passage connecting the pump and the injector in order to avoid pressure pulsations.

However, since this pressure accumulator has a large capacity suitable for normal operation in which a large amount of oil is pumped, it has an adverse effect when starting the engine.

That is, at the time of starting, the pump is driven by the rotation of the engine by the starter motor, but since oil is consumed by operating the injector at the same time as starting, it takes time for the pressure in the pressure accumulator to reach a predetermined value.

As a result, the injector does not operate ideally, and if conditions are bad, combustion becomes unstable, causing smooth or difficult starting.

In view of the drawbacks of the prior art, it is an object of the present invention to provide a configuration that can stably ensure fuel oil pressure to the injector immediately after starting.

According to the present invention, in a fuel injection device having an injector operated by fuel oil pressure from a pressure source driven by an engine, the injector is supplied via the pressure source pump and a small-capacity first pressure accumulator. and the downstream side of the first pressure accumulator is connected to a large-capacity second pressure accumulator via a throttle,
A fuel injector is provided in which the second pressure accumulator is bypassed from the passage connecting the first pressure accumulator to the injector and is connected to the injector via a check valve.

The pressure in the first pressure accumulator with a small working capacity rises immediately after starting, so that the operation of the injector is ensured.

In addition, the pressure introduced through the throttle gradually increases the pressure in the large capacity second pressure accumulator, ensuring the pressure necessary for normal operation.

Embodiment The fuel injection system will be described below with reference to the drawings. The fuel injection device is composed of an injector 1, a pressure source 6, a controller 5, and a fuel tank 7.

The injector 1 basically consists of a nozzle 9 and a plunger 1.
1, spool valve 13, and three solenoid valves 15.17.1
It consists of 9.

The solenoid valves 15, 17, and 19 share the role of controlling the operation of the injector as follows.

That is, if the solenoid valve 17 is open and the solenoid valve 19 is closed, the pressure in the spool valve drive chamber 20 will rise due to the fuel oil pressure from the pressure source 3, causing the spool valve 13 to move against the spring 21 and to the right, opening port a and closing port b.

Therefore, the fuel oil pressure from the pressure source 3 lowers the plunger 11, pressurizes the fuel in the fuel chamber 23, and the fuel is injected from the nozzle 9 into a combustion chamber (not shown).

Next, when the solenoid valve 17 is returned to the closed position and the second solenoid valve 19 is switched to the open position, the pressure in the spool valve drive chamber 20 is released to the tank 7, so that the spool valve 13 is rotated by the force of the spring 21. to the left, closing port a and opening port b.

After this, when the solenoid valve 15 is opened, the plunger 11 is raised by the fuel pressure from the pressure source 3 introduced into the fuel chamber 23 via the check valve 25, and at the same time, fuel for the next injection enters the fuel chamber 23. is filled with.

The controller 5 controls the opening and closing of the three electromagnetic valves 15, 17 and 19 described above.

That is, the controller 5 includes an engine rotation speed sensor S.
1. Accelerator pedal depression amount detection sensor S2, engine temperature sensor S3, engine cylinder mark sensor S4, emergency state detection sensor such as fuel leakage from piping force or engine overrun, etc., sensor S6 for detecting oil pressure from pressure source 3. Signals are input, and in response to the signals from these sensors, the controller 5 opens and closes the three solenoid valves 15, 17, and 19, for example, at the timing shown in FIG.

The analog or digital configuration and operation of the controller 5 are well known and are not relevant to the main part of the present invention, so a description thereof will be omitted.

According to the present invention, the pressure source 3 for pumping fuel to the injector 1 is constructed as follows.

That is, the pressure source 3 includes an engine-driven pump 31, a first pressure accumulator 33 with a small capacity, and a second pressure accumulator 35 with a large capacity.
are the main components.

The first pressure accumulator 33 is connected downstream of the pump 31 and is connected to the passage 3
6 to the injector 1.

The second pressure accumulator 35 is connected downstream of the first pressure accumulator 33 via a throttle 37 .

Furthermore, the second pressure accumulator 35 is in a position bypassed from the passage 36 connecting the first pressure accumulator 33 to the injector 1 , and the second pressure accumulator 35 is connected to the injector 1 via a check valve 39 . .

Furthermore, the second pressure accumulator 35 is connected to the fuel tank 7 via the pressure regulating valve 41.
connected to the side.

Note that 43 is a strainer. The operation of the present invention will be described below. At startup, the pump 31 is rotated by a portion of the driving force of a starter motor (not shown), and oil enters the first pressure accumulator 33.

The flow rate to the second pressure accumulator 35 is kept small by the function of the throttle 37, and the check valve 39 prevents the pressure from flowing out from the passage 36 to the pressure accumulator 35, so that the first pressure accumulator with a small capacity is 33 generates a large pressure immediately after starting, and the injector 1 becomes operable, improving starting performance.

Incidentally, the injectors may operate at all %WJ, but the cylinder reduction operation (the first pressure accumulator 33 is connected to only some of the injectors due to the configuration, or even if all the injectors are connected, the operating cylinders are limited by the controller), Alternatively, the effect is further improved by stopping the operation for a certain period of time (for example, until the output of the pressure sensor S6 that detects the fuel oil pressure of the pressure source 3 reaches a specified value).

Via the throttle 37, fuel is gradually introduced into the second pressure accumulator 35, so that the pressure in this second pressure accumulator 35 reaches the pressure determined by the pressure regulating valve 41 after the time period from start-up has elapsed.

At this time, the check valve 39 is opened, and the hydraulic pressure from the second pressure accumulator 35 can be supplied to the injector 1, allowing smooth entry into normal operation.

In the above configuration, the details of the structure of the injector and the type of hydraulic oil do not matter.

For example, the pressure source may consist of two systems: a high pressure for driving the piston and a low pressure for driving the spool valve.

Further, a device such as a bladder type accumulator or a surge tank may be used as the first pressure accumulator 33, but since the capacity is small, it is also possible to configure the first pressure accumulator by the volume of the piping.

Effects of the invention According to the invention, a small-capacity first pressure accumulator 33 and a large-capacity second pressure accumulator 35 are provided together, and at the time of startup, fuel oil pressure can be quickly obtained in the first pressure accumulator 33. Injection is performed by using the engine, and after transition to steady operation, fuel oil pressure obtained in the second pressure accumulator 35 is used to perform injection.

Therefore, it is possible to improve startability without affecting the injection operation during normal operation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the overall configuration of the present invention, and FIG. 2 is an operation timing diagram of the solenoid valve in FIG. 1. 1... Injector, 3... Pressure source,
31... Pump, 33... First pressure accumulator, 35... Second pressure accumulator, 37...
Throttle, 39... Check valve.

Claims (1)

[Scope of utility model registration request] In a fuel injection device having an injector actuated by fuel oil pressure from a pressure source driven by an engine, a pump of the pressure source is connected to the injector via a first pressure accumulator of small capacity; The downstream side is connected via a restriction to a second pressure accumulator of large capacity, the second pressure accumulator being in a position bypassed from the passage connecting the first pressure accumulator to the injector, and via a check valve. Fuel injection device connected to the injector.