JPH0124376Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel pressure control device for an electronically controlled fuel injection engine equipped with a turbocharger, and in particular, the invention relates to a fuel pressure control device for an electronically controlled fuel injection engine equipped with a turbocharger. This invention relates to a system that prevents evaporation of fuel in a fuel supply system during hot soaking by acting on a rotor.

[Technical background of the invention] In an electronically controlled fuel injection engine, fuel injection is controlled by controlling the opening time of the fuel injection valve. It is necessary to keep the fuel pressure constant. A pressure regulator is generally employed to maintain constant fuel pressure. This pressure regulator adjusts the opening of the on-off valve in response to changes in the internal pressure of the intake pipe of the internal combustion engine (hereinafter simply referred to as intake pressure), and adjusts the amount of fuel returned to the fuel supply source, thereby pumping the fuel into the fuel pump. It has the function of controlling the fuel pressure from the fuel injection valve to the fuel injection valve at a constant level.

Incidentally, fuel pressure is normally controlled to a limit of +2.55 kg/cm ² due to its relationship with gas concentration and fuel efficiency.
Therefore, when the engine is hot soaked immediately after stopping, the fuel pressure reaches a maximum of +2.55Kg/ ^cm2 , but if vapor is generated at this pressure of 2.55Kg/ ^cm2 , it becomes difficult to restart the engine, which is a problem. Become. Here, hot soak is when the rotation is high and the load is high.
This refers to the period during which the internal combustion engine is in a high temperature state due to a sudden rise in temperature when the internal combustion engine is suddenly stopped.

Therefore, in order to prevent vapor lock during hot soak, a bypass passage is provided between the fuel passage and the fuel return passage, and the bypass passage is opened during hot soak to allow the vapor generated in the fuel passage to escape to the fuel return passage. (Utility Model Application Publication No. 57-115952) has been published in the past.

[Problems with the Background Art] However, the above-mentioned conventional devices do not actively prevent the generation of vapor, but instead adopt a passive means of releasing the residual pressure in the fuel passage and letting the generated vapor escape into the fuel tank. Therefore, even if the difficulty in starting due to the vapor lock could be resolved, a new problem of starting difficulty due to the loss of residual pressure would arise, and therefore a sufficient effect could not always be achieved. Moreover, engines with turbochargers generally cause a rise in engine compartment temperature compared to engines without turbochargers, and the volatility of gasoline in the market has also improved.
The above-mentioned conventional technique of lowering the fuel pressure only promotes the generation of vapor in the fuel supply system including the fuel injection valve, but does not reduce it, so vapor lock cannot be effectively prevented. The difficulty of hot restart could not be resolved.

As a related technology, "Fuel pressure control device for electronically controlled fuel injection engine" (1987--
193965) and “vapor lock prevention device”
(Utility Model Application Publication No. 57-115952) has been proposed.

[Purpose of the invention] The present invention was developed in view of the above-mentioned conventional problems.The purpose of this invention is to actively increase fuel pressure during hot soaking, where vapor is likely to be generated, to effectively reduce vapor generation in the fuel supply system. It is an object of the present invention to provide a fuel pressure control device which prevents this from occurring and reliably eliminates engine troubles caused by hot soaking.

[Summary of the invention] In order to achieve the above object, the fuel pressure control device of the present invention uses a pressure control device that changes the valve opening pressure based on the differential pressure between the fuel chamber and the pressure chamber to constantize the fuel pressure in the fuel supply system. a regulator, a pressure accumulating means for accumulating the pressure of the air pressure source to make the pressure higher than the fuel chamber pressure during hot soak, a switching valve for switching and connecting the pressure chamber from the engine intake system to the pressure accumulating means; The device is equipped with a switching valve actuating means for switching operation during hot soaking.

Preferably, the air pressure source is supercharging pressure from a turbocharger. Further, the switching valve operating means is
Preferably, the driving circuit operates the switching valve when the cooling water temperature or the temperature in the engine room is above a predetermined temperature and the ignition switch is off.

In either form, the switching valve operating means operates during hot soak, and the switching valve switches and connects the pressure chamber of the pressure regulator from the engine intake system to the pressure accumulating means. The pressure of the air pressure source is accumulated, and air having a higher pressure than the fuel chamber pressure during hot soak is applied from the pressure accumulation means to the pressure chamber of the pressure regulator. A pressure difference is created between the fuel chamber and the pressure chamber of the pressure regulator, the valve opening pressure changes in a direction that reduces the amount of fuel returned, and the fuel pressure increases. Therefore, generation of vapor in the fuel supply system is effectively prevented. As a result, vapor lock is obviated and the difficulty of hot restart is eliminated.

[Embodiment of the invention] Hereinafter, a preferred embodiment of the fuel pressure control device according to the invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a fuel pressure control device showing an embodiment of the present invention.

As shown in the figure, 1 is a fuel supply source, from which fuel is pumped by a fuel pump 2 and flows through a fuel filter 3 to a fuel injection valve 4, and an intake pipe 6 leading to each cylinder 5 from the tip of the fuel injection valve 4. They are simultaneously injected inside. Further, the remaining fuel that is not injected returns to the fuel supply source 1 through the fuel chamber below the diaphragm in the pressure regulator 7. The line from the fuel pump 2 to the fuel chamber of the pressure regulator 7 constitutes the fuel supply system 20 of the present invention. In the pressure regulator 7, an intake pressure for adjusting the force of the spring is introduced into the pressure chamber 21 above the diaphragm, and if the fuel pressure in the fuel chamber is higher than the sum of the spring and intake pressure, Overcoming the pressure sum, the diaphragm is pushed up, the on-off valve 8 is opened, and the fuel returns to the fuel supply source 1. However, if the fuel pressure is low, the on-off valve 8 remains closed and the fuel does not return to the fuel supply source 1. Due to this action, the fuel pump 2
The fuel pressure from the pressure regulator 7 to the pressure regulator 7 is kept constant. On the other hand, intake pressure is introduced into the pressure chamber 21 of the pressure regulator 7 through an introduction pipe 10 branched from the middle of the intake pipe 6 extending from the turbocharger 9 to the cylinder 5.

A turbo supercharger 9 is installed downstream of the turbo supercharger 9.
A pressure accumulating means 11 is provided for accumulating the supercharging pressure as a positive pressure working fluid to make the pressure higher than the fuel chamber pressure during hot soak. In this embodiment, this pressure accumulating means 11 is constituted by a high pressure chamber with a check valve, and maintains high pressure even when the turbocharger 9 is stopped. Furthermore, although the supercharged air from the turbocharger 9 is used as the positive pressure working fluid, an air pressure source separate from the supercharged air may be used.

On the other hand, the working fluid from the pressure accumulating means 11 is sucked into the introduction pipe 10 that introduces the intake pressure into the pressure chamber 21 of the pressure regulator 7 in order to close the on-off valve 8 of the pressure regulator 7. A switching valve 12 is provided to introduce air into the pressure chamber 21 of the pressure regulator 7 instead of atmospheric pressure and throttle the amount of fuel returned to the fuel supply source 1. The switching valve 12 is, for example, a solenoid-type two-way valve that selectively switches the introduction pipe 10 on the pressure regulator 7 side to the intake pipe 6 and the pressure accumulating means 11.

The switching valve 12 is provided with a switching valve actuating means 15 including a temperature switch 13 that detects that the cooling water temperature or the temperature in the engine room is higher than a predetermined temperature, and an ignition switch 14 in parallel. There is. The switching valve 12 is connected to the pressure accumulating means 11 side only when the ignition switch 14 is turned OFF, the engine is stopped, and the temperature switch 13 is turned OFF by detecting that the cooling water temperature is higher than a predetermined temperature. Under other conditions, the configuration is such that it is connected to the intake pipe 6 side. Note that 16 in the figure is a battery.

The operation of this embodiment having the above configuration will be described.

If the intake pressure is simply introduced into the pressure chamber 21 of the pressure regulator 7 during a hot soak when the engine is stopped after high-speed driving, the intake pressure will drop to atmospheric pressure over time. The on-off valve 8 opens and the return amount increases, and the absolute pressure of the fuel also decreases as the differential pressure decreases while maintaining the differential pressure of 2.55 Kg/cm ² . Moreover, this pressure difference also applies to the check valve of the fuel pump 2 or the on-off valve 8.
Since the fuel pressure cannot be maintained completely due to leakage, the absolute pressure of the fuel decreases rapidly, and becomes a cause of vapor generation during hot soaking. On the other hand, the volatility of gasoline fuel is increasing year by year, and in the case of engines equipped with a turbo supercharger 9, vapors are generated due to the high temperature of the engine compartment, in combination with the above factors. This makes hot restart difficult.

However, in the present invention, the pressure chamber 21 is used in the pressure regulator 7 instead of the intake pressure during hot soak.
By applying high-pressure working fluid to the
The above-mentioned problem is resolved. That is, when the switching valve operating means 15 detects the hot soak time after the engine is stopped, the switching valve 12 is activated by the pressure regulator 7.
The inlet pipe 10 communicating with the pressure chamber 21 is switched and connected from the intake pipe 6 to the pressure accumulating means 11. Due to this switching connection, high-pressure working fluid flows from the pressure accumulating means 11 into the pressure chamber 21 of the pressure regulator 7, and the on-off valve 8
is closed and the amount of fuel returned to the fuel supply source 1 is stopped. The inflow of the working fluid from the pressure accumulating means 11 is as follows:
Although it depends on the amount of pressure accumulated in the pressure accumulation means 11, since it has a check valve to prevent backflow, it can continue for a long time until the engine temperature is sufficiently lowered. Therefore, the fuel pressure within the fuel supply system 20 from the fuel pump 2 to the pressure regulator 7 can be maintained at a large value regardless of the intake pressure. the result,
The generation of vapor is suppressed, vapor lock can be effectively prevented, hot restart becomes smooth, and starting performance is improved.

When not hot soaking, the switching valve operating means 15 switches and connects the inlet pipe 10 leading to the pressure chamber 21 of the pressure regulator 7 to the intake pipe 6, so that the pressure chamber 21 of the pressure regulator 7 Intake pressure is introduced into the engine, and the differential pressure between the fuel pressure and the intake pressure is maintained at a predetermined value of 2.55 kg/cm ² . Therefore, increases in gas concentration, fuel consumption, and CO that would occur if the fuel pressure was too high can be effectively avoided.

As described above, according to the above embodiment, the fuel supply system 20 during hot soaking can be improved without impairing the operating performance.
It is possible to effectively solve the problem of hot restart caused by vapor generation inside the engine.

FIG. 2 shows another embodiment of the present invention, which is particularly applied to an engine equipped with an intercooler 17. In order to prevent fuel evaporation, it is effective to increase the pressure of the fuel supply system. Intercooler 17 if equipped with intercooler 17
Since there is a pressure loss due to There is.

Further, the drive circuit serving as the switching valve actuating means 15 is a series circuit of the ignition switch 14 and the controller 18, and the ignition switch 14 is turned ON.
The switching valve 12 can also be controlled later by the controller 18 in accordance with engine operation, thereby optimizing the fuel pressure.

[Effects of the invention] In summary, according to the invention, during hot soaking, air with a pressure higher than the fuel chamber pressure is added from the pressure accumulating means to the pressure chamber of the pressure regulator, so that the fuel pressure in the fuel supply system can be increased. to raise the level of
The generation of vapor within the fuel supply system can be effectively prevented. Therefore, the difficulty of hot restart caused by this can be reliably resolved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a preferred embodiment of a fuel pressure control device according to the present invention, and FIG. 2 is a block diagram showing a main part of another embodiment. In the figure, 1 is a fuel supply source, 7 is a pressure regulator, 8 is an on-off valve for the pressure regulator, 9 is a turbo supercharger, which is an example of a pneumatic source, and 11 is a pressure regulator.
12 is a pressure accumulating means, 12 is a switching valve, 15 is a switching valve operating means, 20 is a fuel supply system, and 21 is a pressure chamber of a pressure regulator.

Claims (1)

[Scope of claim for utility model registration] 1. A pressure regulator that stabilizes the fuel pressure in the fuel supply system by changing the valve opening pressure based on the differential pressure between the fuel chamber and the pressure chamber, and accumulating the pressure of the air pressure source. a pressure accumulating means for making the fuel chamber pressure higher than the pressure in the fuel chamber during a hot soak; a switching valve for switching and connecting the pressure chamber from the engine intake system to the pressure accumulating means; and a switching valve operating means for switching and operating the pressure chamber during a hot soak. A fuel pressure control device characterized by: 2. The fuel pressure control device according to claim 1, wherein the air pressure source is supercharging pressure from a turbocharger. 3. Registration of a utility model characterized in that the switching valve operating means is a drive circuit that switches and operates the switching valve when the cooling water temperature or the temperature in the engine room is above a predetermined temperature and the ignition switch is off. A fuel pressure control device according to claim 1.