JPH0146711B2 - - 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 have an injector that is actuated by fuel oil pressure from a pressure source driven by an engine. In this type of device, the pressure source includes a pressure accumulator located between the pump and the injector, which suppresses pulsations in the hydraulic pressure fed from the pump to the injector and makes it constant. However, in this case, the presence of the pressure accumulator causes operational instability when starting the engine. In other words, the hydraulic pressure required to start the engine is obtained by using the driving force of the starter motor, for example, but at the time of starting, for example, oil is consumed in the injector immediately after starting, and oil is also consumed from the pump discharge side to the pressure accumulator and injector. Since the volume on the inlet side is large, the pressure in the pressure accumulator cannot be raised quickly, and the operation of the injector becomes uncertain, resulting in combustion fluctuations, resulting in uneven starting, and even inability to start under poor conditions.

Furthermore, even when the engine is not starting up, if there is a sudden transition from low-pressure injection to high-pressure injection, the volume is large, so the pressure cannot be raised quickly and optimum fuel cannot be obtained.

The present invention aims to solve the drawbacks of the conventional technology and improve engine performance such as startability.
To achieve this purpose, the pressure pump is designed so that its pressure feeding timing is synchronized with the injector's operation timing, and when the pressure of the pressure source is below a predetermined value, such as during startup, the pressure pump and the injector are directly connected. The injector can be operated directly with the discharge pressure of 100 ml, and after the fuel pressure rises and stabilizes to a specified value, it is passed through the pressure accumulator.

The configuration of the present invention will be specifically explained below with reference to the drawings. FIG. 1 shows the conceptual configuration of the present invention, in which the fuel injection device includes the injector 1, fuel pressure source 3, controller 5, and fuel tank 7. It consists of

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 15
is open (FIG. 2 A to B), 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, and the port a
is opened and port b is closed. Therefore, the hydraulic pressure from the pressure source 3 causes the plunger 11 to descend and the fuel chamber 2
The fuel in the nozzle 9 is pressurized to overcome the setting force of the spring 24 to open the nozzle 9, and the fuel is injected into a combustion chamber (not shown). When the solenoid valve 17 opens (FIG. 2 C to D), the pressure in the chamber 20 is released to the tank 7, so the spool valve 13 is displaced to the left in the figure by the force of the spring 21, closing port a and then Open port b. After that, if the solenoid valve 19 is opened (FIG. 2 E to F), the plunger 11 can be 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, the The chamber 23 is filled with fuel for 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
Signal from _S6 is input. In response to signals from these sensors, the controller 5 opens and closes the three solenoid valves during one cycle of the engine (that is, two revolutions of the engine in a 4-cycle engine) as shown in FIG. 2, for example. It should be noted that the hardware and software configurations of the controller 5 are well known, so their explanation will be omitted.

The hydraulic power source 3 that produces pressure-feeding oil to the injector 1 includes an engine-driven pump 31, a pressure accumulator 33, and a pressure regulating valve 3.
5, a filter 36, and a solenoid valve 41 driven by the controller 5. In the illustrated position, the electromagnetic switching valve 41 directly connects the pump 31 to the injector 1 via a passage 43. However, injector 1 is in passage 4.
It is connected to the pressure accumulator 33 via 5. Solenoid valve 4
1 switches to the right side, the pump 31 communicates with the injector 1 via the passage 46, but at this time the direct connection passage 43 is separated from the pump 31. pump 31
It is essential in the present invention that the pumping timing is designed to be synchronized with the injection operation timing of the injector. That is, during the period from A to B in FIG. 2 when the injector injects fuel, the pump performs pressure feeding timings G to H as shown in FIG. 3.

The operation of the present invention will be described below. At startup, the pressure detected by the pressure sensor S ₆ is small, and upon receiving this signal, the controller 5 sets the solenoid valve 41 to the left port position in the figure, and the pump 31 and injector 1 are connected to each other. They are directly connected via the passage 43. As shown in Figs. 2 and 3, the injector's injection operation timings A to B and the pump's pressure feeding timings G to H are synchronized, so even if the injector 1
Even if the average pressure applied to the nozzle 9 is small, it can exceed the required operating pressure of the injector during injection (peak pump pressure), so fuel is injected from the nozzle 9. Therefore, starting is stabilized. In this case, some of the oil escapes to the pressure accumulator 33 through the passage 45 and gradually increases the pressure there.

When the pressure detected by the sensor S ₆ increases as time passes after starting, the controller 5 sets the solenoid valve 41 to the right port position. the result,
The direct connection channel 43 is separated from the pump 31, and the pump is sent to the injector 1 only via channels 46, 45, which are provided with a pressure accumulator 33. As a result, the hydraulic pressure supplied to the injector 1 is kept constant by the pressure accumulator 33.
Ideal operation is realized.

The embodiment shown in FIG. 4 is a case where the above-mentioned basic structure of the present invention is applied to a multi-cylinder engine. In this case, there are 4 cylinders, 1-a, 1-b, 1-c, 1
-d four injectors are provided. There are 4 pumps: 31-a, 31-b, 31-c, 31-d.
The injection operation timing and pumping timing of the injector and pump section of the corresponding cylinder are synchronized in the same manner as described in FIGS. 2 and 3. A spool valve 41 is provided for each cylinder to switch communication between the inlet port e and the outlet port c or d. That is, the inlet port e is connected to the corresponding pump section 31-a, 31-b, 3
1-c or 31-d. One outlet port c is independent piping 43-a, 43-b, 43-
c, 43-d corresponding injector 1-
a, 1-b, 1-c, and 1-d, and the other outlet port d is connected to the pressure accumulator by a common pipe 46. In addition, the injector is connected to the passage 45-
It is connected to the pressure accumulator 33 by a, 45-b, 45-c, and 45-d. Unlike in FIG. 1, the spool valve 41 is operated by the hydraulic pressure acting on the hydraulic chamber 70.

To describe the operation of the embodiment shown in FIG. 4, at the time of starting, the pressure in the chamber 70 is small, so the pressure in the chamber 70 is small, so the device assumes a position displaced to the right in the figure by the force of the spring 72, and ports e and c are electrically connected. Therefore, each pump section 31-a, 31
-b, 31-c, and 31-d are directly connected to the injectors 1-a, 1-b, 1-c, and 1-d of the corresponding cylinders, respectively, and the timings of both are as shown in Figs. Since the injectors are synchronized each time, the injector opens according to the principle described in FIG. 1, and stable starting can be performed. At this time, excess oil is removed from passages 45-a and 45-
b, 45-c, and 45-d to return to the pressure accumulator 33 and gradually increase the pressure there.

When the pressure in the pressure accumulator 33 increases and the pressure in the hydraulic chamber 70 reaches a predetermined value, the spool 41 resists the spring 72 and is displaced to the left in the figure, bringing ports e and d into electrical continuity, and connecting each pump section 31-a. ,31-b,3
1-c, 31-d are all connected to the pressure accumulator 33,
Start normal operation.

In the embodiment shown in FIG. 4 as well, the spool valve 41
Instead, an electromagnetic switching valve similar to that shown in FIG. 1 can be used.

Since the feature of the present invention is that the injector and the pump are directly connected in a timely manner at the time of starting, the specific structure of the injector and the hydraulic power source may be of any type.

It is preferable to use a double-action type pump 31, as this will provide another pressure feed when no injection is performed, and it will quickly reach stable operation. Moreover, it is preferable that the pump 31 is equipped with a check valve on the discharge side.

As described above, in the fuel injection device for an internal combustion engine of the present invention, when the pressure source pressure is below a predetermined pressure, such as during startup, the pump and injector can be directly connected, and the apparent volume Higher pressure injection can be obtained by reducing the pressure and using the instantaneous pumping force (peak pressure).

Therefore, desired injection can be obtained more quickly than in conventional fuel injection devices, and engine performance such as improved startability is improved. Furthermore, it becomes possible to obtain optimal combustion by high-pressure injection during transient operation without driving torque loss, and it also has the effect of purifying exhaust gas and improving fuel efficiency.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the basic configuration of the present invention, Figure 2 is a schematic diagram showing the basic configuration of the present invention.
3 is a timing diagram of an injector, FIG. 3 is a timing diagram of a pump, and FIG. 4 is a diagram showing an example of application of the present invention to a multi-cylinder engine. 1...Injector, 3...Pressure source, 33...
Pressure accumulator, 41... switching valve.

Claims (1)

[Claims] 1. In an internal combustion engine equipped with an injector that is operated by pressure from a pressure source driven by the engine, the pressure source includes a pump that rotates in synchronization with the engine, and the pressure feeding timing of the pump and the operation timing of the injector are synchronized. are selected so that they are substantially synchronous, and when the pressure of the pressure source is below a predetermined pressure, the pump is connected directly to the injector, and when the pressure of the pressure source exceeds the predetermined pressure, the pump is connected to the accumulator. A fuel injection device characterized by having a switching valve that switches the path between these two states according to the pressure of a pressure source so that the fuel injection device is connected to an injector via the fuel injection device.