JPH0144899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine.

There are fuel injection devices that include 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 oil is consumed by operating the injector at the same time as starting, so 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 secure oil pressure to the injector immediately after startup. In order to achieve this objective, the present invention provides a passage that bypasses the existing pressure accumulator, and also provides a small-capacity second pressure accumulator as necessary, and at the time of startup, the pump is connected to the main pressure accumulator. By separating it from the injector and communicating only with the bias passage, stable pressure can be applied to the injector from an early stage.

The structure of the present invention will be explained in detail below with reference to the drawings. In FIG. 1, the fuel injection device is comprised of an injector 1, a fuel oil pressure source 3, a controller 5, and a fuel tank 7.

The injector 1 basically includes a nozzle 9, a plunger 11, a spool valve 13, and three electromagnetic valves 15, 17, and 19. Solenoid valve 1
5, 17, and 19 share the role of controlling the operation of the injector as follows. That is, the solenoid valve 17 is open,
When the solenoid valve 19 is in the closed position, the pressure in the chamber 20 increases due to the fuel oil pressure from the pressure source 3, and the spool valve 13 is displaced to the right in the figure against the spring 21, opening port a. Let b be closed. Therefore, the hydraulic pressure from the pressure source 3 causes the plunger 11 to descend,
The fuel in the fuel chamber 23 is pressurized, and the fuel is injected from the nozzle 9 into a combustion chamber (not shown). Next, by returning the solenoid valve 17 to the closed position and switching the solenoid valve 19 to the open position, the pressure in the chamber 20 is released to the tank 7, and the spool valve 13 is displaced to the left in the figure by the force of the spring 21. , closes port a and then opens port b. After this, if the solenoid valve 15 is opened, the fuel chamber 23
The plunger 11 can be raised by the fuel pressure from the pressure source 3 introduced through the check valve 25, and at the same time the chamber 23 is filled with fuel for the next injection.

The controller 5 includes the three electromagnetic valves 15 described above,
17 and 19 are opened and closed. That is, the controller 5 includes an engine rotation speed sensor S ₁ , an accelerator pedal depression amount detection sensor S ₂ , an engine temperature sensor S ₃ , an engine cylinder mark sensor S ₄ , and a sensor for detecting emergency conditions such as fuel leakage from piping and engine overrun. S ₅ , sensor for detecting oil pressure from pressure source 3
Signals from _S6 are input, and in response to the signals from these sensors, the controller 5 opens and closes the three electromagnetic valves at the timing shown in FIG. 2, for example. The analog or digital configuration and operation of the controller 5 are well known and are not related to the main part of the present invention, so a description thereof will be omitted.

According to the present invention, the hydraulic power source for forming the pressure-feeding oil to the injector 1 is constructed as follows. That is, the main components of the pressure source include an engine-driven pump 31, a large-capacity main pressure accumulator 33, a small-capacity sub-pressure accumulator 35, and a spool-type control valve 37. The control valve 37 has a pressure acting on the hydraulic chamber 39 and a spring 41.
Port C moves left and right as shown in the figure in balance with the setting force.
and d. Port c is pump 31
The port d is connected to the main pressure accumulator 33. The main pressure accumulator 33 is further connected to the injector 1 via a check valve 43 and to the tank 7 via a pressure regulating valve 45 . The auxiliary pressure accumulator 35 is provided so as to bypass the main pressure accumulator 33, and is located on the passage 51 between the injector 1 and the pump discharge side. Furthermore, the pressure of the auxiliary pressure accumulator 35 acts via the passage 53 on the working chamber 39 of the spool valve. Note that an independent device such as a bladder type accumulator or a surge tank can be used as the auxiliary pressure accumulator 35, but since the capacity is small, the capacity of the piping 51 between the pump 31 and the injector 1 should be appropriately designed. By doing so, it is also possible to provide a function as a pressure accumulator.

In this way, the pump 31
3, port d, to the injector 1 via the first passage including the check valve 43, and to the injector 1 via the second passage including the auxiliary pressure accumulator 35 and the passage 53.
The system is designed to supply pressure-fed oil to both.

A strainer 5 is installed between the pump 31 and the tank 7.
5 is provided to purify the fuel from the tank.

The operation of the present invention will be described below. When the engine is started, the pump 31 is rotationally driven by a starter motor (not shown), and pressure is generated on the discharge side of the pump 31 and introduced into the sub-accumulator 35. Working chamber 3 during startup
Since the pressure inside pump 9 is small, the spool valve 37 is positioned so as to separate ports c and d by the action of the spring 41, and the check valve 43 is activated so that the pump 31 is separated from the main pressure accumulator 33. Thus, pump 3
1 and injector 1 are auxiliary pressure accumulator 3 with small capacity.
5. Communicate with each other only through 5. Therefore, the pressure within this pressure accumulator 35 quickly rises to a predetermined pressure, so that proper operation of the injector 1 is achieved immediately after starting. In addition, the injector 1 operates the solenoid valves 15, 17, and 19 as shown in FIG.
However, if the controller 5 is configured so that the solenoid valves 15, 17, and 19 do not operate until the pressure detected by the pressure sensor _S6 reaches a predetermined value, it is possible to perform the normal operation of opening and closing. Sometimes oil is not consumed in injector 1, so sub-accumulator 35
The pressure rise will be more rapid, resulting in a favorable result. Alternatively, the effect of rapid pressure rise can be obtained even if only some of the cylinders are operated at the time of startup based on the signal from the cylinder mark sensor, or by connecting pressure accumulators to only some of the injectors.

In this way, when the pressure in the sub-accumulator 35 increases to a specified value or higher, the spool valve 37 opens in response to this pressure.
moves to the right in the figure against spring 41, and ports c and d
The flow path area between the main pressure accumulator 33 and the main pressure accumulator 33 introduces surplus oil in an amount corresponding to the pressure of the pressure accumulator 35. Therefore, the pressure in the main pressure accumulator 33 gradually increases while maintaining the pressure in the sub pressure accumulator 35 at a specified level. When the pressure in the main pressure accumulator 33 increases in this manner, the pressure regulating valve 45 operates to adjust the pressure, and the pressure is supplied to the injector 1 via the check valve 43, resulting in a normal operating state.

The embodiment shown in FIG. 3 is characterized in that a pressure regulating valve 60 is disposed between the auxiliary pressure accumulator 35 and the main pressure accumulator 33 instead of the spool valve 37 in FIG. The pressure regulating valve 60 disconnects the main pressure accumulator 33 from the pump 31 and quickly increases the pressure to the injector 1 until the pressure in the sub pressure accumulator 35 reaches a specified value. Further, when the pressure in the sub pressure accumulator 35 increases, the pressure regulating valve 60 introduces excess oil into the main pressure accumulator 33 in accordance with this pressure, thereby transitioning to a normal operating state. The embodiment shown in FIG. 3 is advantageous in that the configuration is simpler than that shown in FIG.

The embodiment shown in FIG. 4 differs from the hydraulic type shown in FIGS. 1 and 3 in that it uses a solenoid valve 80 that is electrically driven by the controller 5. The pump 31 is connected to the main pressure accumulator 33 or the auxiliary pressure accumulator 35 by a three-position electromagnetic switching valve 80. The pressure regulating valve 45 is provided between the sub-pressure accumulator 35 and the tank 7.

To describe the operation of this embodiment, when the engine starts, the pressure detected by the sensor _S6 is small, and in response to this signal, the controller 5 sets the switching valve 80 to the leftmost port position in the figure. Therefore, the pressure from the pump 31 is pumped and introduced only to the sub-accumulator 35, and the pressure of the sub-accumulator 35, which has a small capacity, quickly rises. When the pressure in the subaccumulator 35 rises to a predetermined value, the sensor _S6 detects this and the controller causes the switching valve 80 to move to the center port position. Therefore, while the hydraulic pressure is continuously supplied to the auxiliary pressure accumulator 35, pressure is also introduced to the main pressure accumulator 33, and the pressure there gradually increases. After passing through such an intermediate state, the controller 5
With the switching valve 80 in the right port position, the pump 3
1 is connected to the main pressure accumulator 33 and enters the normal operating state. At this time, since the main pressure accumulator 33 and the sub pressure accumulator 35 are connected through the check valve 43, the sub pressure accumulator 33
5 performs an auxiliary pressure accumulation operation, and a pressure regulating valve 45
It also serves as a passageway.

It goes without saying that in each of the embodiments shown in FIGS. 1, 3, and 4 above, the structure of the injector and the type of hydraulic oil are not characteristics, so it does not matter what they are.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention, FIG. 2 is a diagram showing an example of the operation timing of the three solenoid valves in FIG. 1, and FIG. 3 is a partial diagram of another embodiment. FIG. 4 shows the third embodiment. 1...Injector, 5...Controller, 7
... Tank, 31 ... Pump, 33 ... Main pressure accumulator, 35 ... Sub-pressure accumulator, 37, 60, 80 ... Control valve.

Claims (1)

[Claims] 1. In an internal combustion engine equipped with an injector 1 operated by pressurized oil from a pump 31, a first passage supplies pressurized oil from the pump 31 to the injector 1 via a main pressure accumulator 33;
The second passages 35 and 53 supply pressurized oil from the pump 31 to the injector 1 by bypassing the pump 31 until the pressure in the second passages 35 and 53 reaches a predetermined pressure at the time of starting the engine. from 1st
The supply of pressurized oil to the second passage 3 is blocked.
A fuel injection device for an internal combustion engine, comprising control means 37, 60, and 80 for supplying pressure-fed oil from a pump 31 only to fuel injection devices 5 and 53.