JPH11236866A - Method and device for feeding fuel to internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To better the fuel injection system of an injection type engine for an automobile, to improve smoothness during the starting of an engine, and to excellently discharge a vaporized fuel in a path. SOLUTION: In a fuel feed method for an internal combustion engine wherein a fuel is pressurized into a high pressure by a high pressure pump 9 and injected directly to a combustion chamber, the sucked fuel is applied in the reverse direction by staggering a timing through inlets 1a and 1b at the two ends of a delivery pipe 1. In this case, since the vaporized fuel in the delivery pipe 1 is discharged to an external part by a pressure generated by a low speed pump 7 during the starting of an engine, starting ability of the engine is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an internal combustion engine applied to a so-called direct injection type engine which directly injects fuel into a combustion chamber.

[0002]

2. Description of the Related Art A mixture of gasoline and air is used as fuel,
In recent years, so-called gasoline engines, which ignite this air-fuel mixture with a spark plug to push down a piston, have recently increased the direct injection of fuel into a combustion chamber like a diesel engine (for example, Japanese Patent Laid-Open No. 7-771).
18, JP-A-7-83134, JP-A-7-293381, etc.).

[0003]

In such a direct-injection engine, wasteful consumption of fuel can be reduced and combustion can be efficiently performed as compared with an in-pipe injection type engine. Although favorable results can be obtained in terms of both fuel efficiency and exhaust gas purification, on the other hand, since a high-pressure pump is required, it is necessary to simultaneously drive two types of low-pressure pump and high-pressure pump as fuel pumps. There is a problem that the burden on the user increases. In addition, when the engine speed is low at the time of starting the engine and when the engine is not stable, the high-pressure pump may not function sufficiently, and on the contrary, the hydraulic pressure generated by the low-pressure pump may be reduced.

[0004] On the other hand, as another problem, the conventional delivery pipe has only one fuel supply inlet, and as a result, evaporative fuel remains inside the delivery pipe as will be described later. Therefore, the fuel pressure may not be maintained properly, and the fuel injection amount may vary. In this regard, none of the above publications has a structure that solves this problem.

[0005] Prior art relating to a direct injection type engine is as follows.
Japanese Patent Application Laid-Open No. H07-77118 discloses a method in which the fuel of the pressure obtained by the low-pressure pump flows by bypassing the high-pressure pump when the rotation speed of the high-pressure pump is low and sufficient fuel pressure cannot be obtained, such as when starting the engine. Although described in the gazette, when the invention of this gazette is applied to a so-called returnless system in which the excess fuel in the delivery pipe is not returned to the upstream side of the high-pressure pump or to the fuel tank, as shown in FIG. When the fuel 2 is added from the fuel inlet 1a in the fuel injector 1 and discharged from the outlet 3 to the injector, the fuel inlet 1a
There is a case where the evaporated fuel 4 remains on the side far from the fuel cell. If the fuel vapor 4 remains here, the fuel pressure will not be maintained properly, and the fuel injection amount may vary.

[0006] The present invention has been made in view of this point, when starting the engine, only the low-pressure pump is started,
It is an object of the present invention to provide a fuel supply method for an internal combustion engine and a device therefor, in which the operation of the low pressure pump is stopped when the function of the high pressure pump becomes sufficient, thereby reducing the load on the engine. At the same time, there is provided a method and an apparatus for stabilizing the fuel supply at the time of starting the engine and quickly discharging the evaporated fuel remaining in the fuel supply system.

[0007]

According to the present invention, there is provided a fuel supply method for an internal combustion engine according to claim 1, wherein the fuel is pressurized to a high pressure by a high pressure pump. In the fuel supply method for an internal combustion engine in which the fuel is directly injected into the combustion chamber, a fuel inlet is provided at both ends of a delivery pipe that distributes the sucked fuel to each cylinder,
Only when the engine is started, fuel is supplied from one inlet of the delivery pipe, and control is performed such that fuel is supplied from the other inlet when the rotation of the engine is stabilized.

According to a second aspect of the present invention, there is provided a fuel supply method for an internal combustion engine in which fuel is pressurized to a high pressure by a high pressure pump and directly injected into a combustion chamber. Fuel is sucked in by the two systems of the pump, and only when the engine is started, the fuel sucked in by the low-pressure pump is supplied from one inlet of the delivery pipe, and when the rotation of the engine is stabilized, the fuel from the high-pressure pump is fed from the other inlet. It is characterized in that it is supplied.

According to a third aspect of the present invention, in the method according to the second aspect, the low-pressure pump is driven by electric power, the high-pressure pump is driven mechanically by the output of an engine, and the flow from the low-pressure pump is controlled. Is supplied from one end inlet of the delivery pipe, and the flow from the high pressure pump is supplied from the other end inlet of the delivery pipe.At the time of starting the engine, the low pressure pump is started first, and the residual fuel in the delivery pipe is supplied to the high pressure pump. It is characterized in that the low-pressure pump is stopped when the fuel is discharged from the fuel supply system to the outside and the rotation of the engine is stabilized.

According to a fourth aspect of the present invention, a low-pressure pump and a high-pressure pump are connected in series, and the suction side of the low-pressure pump is opened in a fuel tank. One outlet of a delivery pipe for distributing fuel to each cylinder is connected to the discharge side, and between the other inlet of the delivery pipe and the suction side of the high-pressure pump, the other end of the delivery pipe is connected from the suction side of the high-pressure pump. A check valve is connected to allow a flow to the inlet side.

In the invention described in claim 5, both the low-pressure pump and the high-pressure pump are opened in the fuel tank, and a fuel inlet is provided at both ends of the delivery pipe. The discharge side of the pump is connected, and the discharge side of the high-pressure pump is connected to the other inlet.

Further, in the invention described in claim 6, both suction sides of the low-pressure pump and the high-pressure pump are opened in the fuel tank, fuel inlets are provided at both ends of the delivery pipe, and the low-pressure pump is provided at one of the inlets. Connect the discharge side of the pump, connect the discharge side of the high-pressure pump to the other inlet, and connect the upper end of the passage whose lower end opens to the fuel tank via the high-pressure pressure regulator to the connection side of the low-pressure pump of the delivery pipe. The upper end of a passage having a lower end opening to the fuel tank is connected to the connection side of the delivery pipe to the high pressure pump via an electromagnetic switching valve and a low pressure regulator, and the fuel pressure holding means and the electromagnetic pressure are connected in parallel with the high pressure pump. A bypass passage provided with a switching valve in series is connected.

According to the present invention, both low-pressure pump and high-pressure pump suction ports are opened in the fuel tank, and fuel inlets are provided at both ends of the delivery pipe. Connect the discharge side of the pump, connect the discharge side of the high-pressure pump to the other inlet, and connect the upper end of the passage whose lower end opens to the fuel tank via the high-pressure pressure regulator to the connection side of the low-pressure pump of the delivery pipe. A bypass passage provided with a low-pressure pressure regulator and an electromagnetic switching valve in series is connected to the connection side of the delivery pipe to the high-pressure pump.

With this configuration, fuel from a low-pressure pump capable of obtaining a stable pressure even when the engine starts at a low rotational speed is supplied from one inlet of the delivery pipe. Residual fuel is discharged from the fuel supply system on the high pressure pump side, which is the other inlet, to the fuel tank side, or from the injector to the combustion chamber of the engine. When the rotation speed of the engine is sufficiently high and stable, the high-pressure pump directly sucks the fuel, so that the low-pressure pump can be stopped.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an embodiment of a fuel supply device for an internal combustion engine according to the present invention will be described below with reference to FIG. Fuel 2 is put in the fuel tank 5,
A filter 6 is provided in the fuel 2. An electric low-pressure pump 7, a filter 8, and a mechanically driven high-pressure pump 9 are connected in series to the filter 6 by a passage 10, and a delivery side of the high-pressure pump 9 is provided with a fuel inlet at both ends. It is connected to one inlet 1 a of the pipe 1. An injector 11 that distributes fuel to each cylinder of an engine (not shown) is connected to the delivery pipe 1.

At the connection point between the low pressure pump 7 and the filter 8,
A passage 13 having a low-pressure pressure regulator 12 whose discharge side is opened to the fuel tank 5 side is connected. At a connection point between the high-pressure pump 9 and the inlet 1a of the delivery pipe 1, the discharge side is opened to the fuel tank 5 side. The passage 15 having the high pressure regulator 14 is connected.
A check valve 16 is connected to the other inlet 1 b of the delivery pipe 1 by a passage 17, the check valve 16 opening in a direction flowing from the passage 10 to the inlet 1 b of the delivery pipe 1.

A control circuit (electronic / electronic)
A control module (abbreviation ECM) 18 is mounted. The control circuit 18 includes an ignition switch ON signal (Ig), a starter switch ON signal (Sta), an engine speed signal (Ne), a throttle opening signal (Tha), and an intake pressure signal (Pin).
And a fuel pressure signal of the delivery pipe 1 described later is input,
The operation of the low-pressure pump 7 is controlled according to those conditions.

When the driver turns on an ignition switch (not shown), the low pressure pump 7 is operated by the output signal of the control circuit 18 and the fuel 2 in the fuel tank 5 is supplied to the high pressure pump 9.
To the suction side. When the engine is started by turning on the starter switch, the high pressure pump 9 also operates. However, when the engine is started, the rotation speed is low (around 400 rpm) and the rotation is unstable. Can not get. At this time, the check valve 16 is opened by the pressure generated by the low-pressure pump 7, and the fuel is supplied from the inlet 1b side. When the fuel is supplied from the inlet 1b in this way, the evaporated fuel 4 collects on the outlet 3 side to the injector as shown in FIG. 2 and is sent to the combustion chamber together with the fuel 2 to be discharged.

The circuit shown in FIG. 3 is another example of the embodiment of the present invention. In this circuit, the suction side of the low-pressure pump 7 is opened through the filter 6 in the fuel tank 5, and the suction side of the high-pressure pump 9 is also opened through the filter 19 through the filter 19.
Open inside. The discharge side of the low pressure pump 7 is connected to one inlet 1 a of the delivery pipe 1 by a passage 21 connecting the filter 8 and the check valve 20. The end of the passage 22 provided with the high-pressure pump 9 is connected to the delivery pipe 1.
Is connected to the other inlet 1b. In the vicinity of the filter 19 in this passage, a check valve 24 that opens in a direction to return the fuel 2 to the fuel tank 5 side through a passage 23 is connected. An accumulator 25 is provided in a part of the passage 22 so as to adjust the pressure of this system.

The upper end of the passage 13 from the high pressure regulator 14 is connected to the fuel inlet 1a on the side of the delivery pipe 1 to which the low pressure pump 7 is connected. Passage 13
Open at the lower end of the fuel tank 5. An upper end of a passage 27 having an electromagnetic switching valve 26 and a low-pressure pressure regulator 12 and having a lower end opening to the fuel tank 5 is connected to an inlet 1 b of the delivery pipe 1 on the side to which the high-pressure pump 9 is connected. In parallel with the high-pressure pump 9, a bypass 28 having a throttle 28 serving as a fuel pressure holding means and an electromagnetic switching valve 29 provided in series is connected.

In the above circuit, a fuel pressure sensor 31 is attached to the delivery pipe 1.
The internal pressure of the fuel is converted into an electric value, and the signal is output to the control circuit 18. Control circuit 18
, Knows the state of the engine based on this signal and the signals described above, and controls the low-pressure pump 7 and the electromagnetic switching valves 26 and 29.

The operation of the above circuit will be described. In the drawing, solid arrows indicate a low-pressure flow of the fuel, and white arrows indicate a high-pressure flow of the fuel.

When the driver starts the engine by turning on an ignition switch (not shown), the low-pressure pump 7 is operated by the output signal of the control circuit 18, and the fuel 2 in the fuel tank 5 is supplied to the inlet 1a side of the delivery pipe 1. To send to. By turning on the starter switch to start the engine, the high-pressure pump 9 also operates. However, when the engine is started, the rotation speed is low and the rotation is unstable. Can not. For this reason, the delivery pipe 1 has an inlet 1b from the inlet 1a side.
The fuel flows to the fuel tank 5 through two paths on the electromagnetic switching valve 26 side and the electromagnetic switching valve 29 side which are open at this time by the output signal of the control circuit 18. At this time, the fuel vapor is discharged together with the fuel 2.

When the rotation of the engine is stabilized and the high-pressure pump 9 functions sufficiently, the control circuit 18 stops the low-pressure pump 7 and closes the electromagnetic switching valves 26 and 29 at the same time. Thereby, the fuel is supplied to the delivery pipe 1 only from the high-pressure pump 9 as indicated by the white arrow. Excess fuel in the delivery pipe 1 flows from the passage 21 to the passage 13, opens the high pressure regulator 14, and returns to the fuel tank 5.

The control performed by the control circuit 18 in the circuit of FIG. 3 will be described with reference to the flowchart of FIG. When control is started in step S1, it is determined in subsequent step S2 whether the engine is operating or stopped,
When the engine is operating, it is determined in the next step S3 whether or not the current rotational speed Ne of the engine is smaller than a predetermined rotational speed NE1. As a result, if the rotational speed is higher than the predetermined rotational speed NE, it is determined in the following step S4 whether the pressure value Pf detected by the fuel pressure sensor 31 is smaller than a predetermined pressure value PF1 set in advance.

When it is determined in step S4 that the pressure value Pf is larger than the predetermined pressure value PF, the two electromagnetic switching valves 26 and 29 are closed.

When it is determined in step S2 that the engine is stopped, in step S3 the engine speed Ne is determined.
Is determined to be smaller than the predetermined rotation speed NE1, and when it is determined in step S4 that the pressure value Pf detected by the fuel pressure sensor 31 is smaller than the predetermined pressure value PF1. At step S6, the two electromagnetic switching valves 26 and 29 are opened, and at step S7, the low-pressure pump 7 is operated.
When the electromagnetic switching valves 26 and 29 are opened, the delivery pipe 1
The residual fuel inside is returned to the fuel tank 1 through the electromagnetic switching valves 26 and 29 at the pressure generated by the low-pressure pump 7.

In step S5, the two electromagnetic switching valves 26, 2
9 is closed, in the following steps S8 and S9, the determination using the rotational speed NE2 and the pressure value PF2 as the second reference values is performed again in the same procedure as performed in steps S3 and S4. Done. That is, at step S9, the current rotational speed Ne of the engine
Is smaller than a predetermined rotational speed NE2 set in advance.

As a result, if the rotational speed is higher than the predetermined rotational speed NE, the pressure value Pf detected by the fuel pressure sensor 31 is set at a predetermined pressure value PF2 in a subsequent step S9.
A determination is made whether it is less than. If it is determined in step S9 that the pressure value Pf is larger than the predetermined pressure value PF2, the low-pressure pump 7 is stopped in step S10, and the process ends in step S11. Thereafter, the same control is repeatedly performed. Becomes

When it is determined in step S8 that the engine speed Ne is lower than the predetermined speed NE2, the pressure value Pf detected by the fuel pressure sensor 31 is lower than the predetermined pressure value PF2. When it is determined that it is smaller, the process proceeds to step S7 to stop the low-pressure pump 5, and proceeds to step S11 to repeat the above-described control.

The circuit shown in FIG. 5 is a modification of the embodiment of the present invention. This circuit is different from the circuit of FIG. 3 in that the throttle 27 provided in the bypass passage 30 in FIG.
Is provided with the low-pressure pressure regulator 12 and the electromagnetic switching valve 26 provided in the first embodiment.

This circuit basically performs the same function as that of FIG. The only difference is that the system for discharging the evaporated fuel in the delivery pipe 1 at the pressure generated by the low-pressure pump 7 is only one system that passes through the bypass passage 30, and the entire flow rate is accordingly passed. And the number of parts can be reduced.

[0033]

The present invention is a fuel supply method and apparatus for an internal combustion engine configured as described above.
According to the first aspect of the present invention, the evaporated fuel in the delivery pipe can be discharged by adding the fuel in the reverse direction from the fuel inlets provided at both ends of the delivery pipe. According to the second aspect of the present invention, the fuel from the low-pressure pump and the fuel from the high-pressure pump are appropriately switched, so that the evaporated fuel can be efficiently discharged. Further, according to the third aspect of the invention, it is possible to discharge the fuel vapor when the engine is started. Since the low-speed pump stops when the rotation of the engine stabilizes, the operation time of the low-speed pump is shortened,
This has the effect of saving power consumption, consequently saving fuel, and requiring only a small capacity pump.

Further, according to the invention of the device described in claim 4, by simply connecting one check valve, the fuel vapor is discharged by the pressure generated by the low pressure pump when the high pressure pump does not function sufficiently. It can be performed. Further, according to the inventions described in claims 5 to 7, it is possible to obtain an apparatus that realizes the method described in claims 1 and 2, respectively.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a case where two fuel inlets are provided in a delivery pipe.

FIG. 3 is a circuit diagram showing another example of the embodiment of the present invention.

FIG. 4 is a flowchart illustrating the operation of a control circuit in the circuit of FIG. 3;

FIG. 5 is a circuit diagram showing still another example of the embodiment of the present invention.

FIG. 6 is a sectional view of a conventional delivery pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Delivery pipe 1a Inlet 1b Inlet 2 Fuel 4 Evaporated fuel 5 Fuel tank 7 Low-speed pump 9 High-speed pump 12 Low-pressure pressure regulator 14 High-pressure pressure regulator 15 Check valve 16 Bypass passage 18 Control circuit 26 Electromagnetic switching valve 29 Electromagnetic switching valve 29

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 37/00 F02M 37/00 C 37/08 37/08 A

Claims (7)

[Claims] 1. A fuel supply method for an internal combustion engine in which fuel is pressurized to a high pressure by a high-pressure pump and directly injected into a combustion chamber, wherein fuel inlets are provided at both ends of a delivery pipe for distributing the sucked fuel to each cylinder. A fuel supply method for an internal combustion engine, wherein fuel is supplied from one inlet of a delivery pipe only when the engine is started, and supplied from the other inlet when the rotation of the engine is stabilized. 2. A fuel supply method for an internal combustion engine in which fuel is pressurized to a high pressure by a high-pressure pump and directly injected into a combustion chamber, wherein the fuel is sucked from a fuel tank by two systems of a low-pressure pump and a high-pressure pump. Only when the engine is started, the fuel sucked by the low pressure pump is supplied from one inlet of the delivery pipe, and when the rotation of the engine is stabilized, the fuel from the high pressure pump is supplied from the other inlet. Engine fuel supply method. 3. The low-pressure pump is driven by electric power, the high-pressure pump is driven mechanically by the output of an engine, and a flow from the low-pressure pump is supplied from one end of a delivery pipe.
The flow from the high-pressure pump is supplied from the other end inlet of the delivery pipe, and at the time of starting the engine, the low-pressure pump is started in advance, and the residual fuel in the delivery pipe is discharged to the outside from the fuel supply system of the high-pressure pump. 3. The method according to claim 2, wherein the low-pressure pump is stopped when the rotation of the engine is stabilized. 4. A low pressure pump and a high pressure pump are connected in series, a suction side of the low pressure pump is opened in a fuel tank, and a discharge side of the high pressure pump has one inlet of a delivery pipe for distributing fuel to each cylinder. And a check valve that allows a flow from the suction side of the high-pressure pump to the other inlet side of the delivery pipe is connected between the other inlet of the delivery pipe and the suction side of the high-pressure pump. A fuel supply device for an internal combustion engine. 5. A low-pressure pump and a high-pressure pump are opened in the fuel tank at both suction sides, fuel inlets are provided at both ends of the delivery pipe, and one of the inlets is connected to a discharge side of the low-pressure pump. A fuel supply device for an internal combustion engine, wherein a discharge side of a high-pressure pump is connected to an inlet. 6. A low-pressure pump and a high-pressure pump are opened at both suction sides in a fuel tank, fuel inlets are provided at both ends of a delivery pipe, one of the inlets is connected to a discharge side of the low-pressure pump, and the other is connected to the other side. The inlet is connected to the discharge side of the high-pressure pump, and the connection side of the delivery pipe to the low-pressure pump is connected to the upper end of a passage whose lower end opens to the fuel tank via a high-pressure pressure regulator. The lower end is connected to the upper end of a passage that opens to the fuel tank via an electromagnetic switching valve and a low-pressure pressure regulator, and a bypass passage provided with fuel pressure holding means and an electromagnetic switching valve in series with the high-pressure pump in parallel. A fuel supply device for an internal combustion engine, wherein the fuel supply device is connected. 7. Opening both suction sides of a low-pressure pump and a high-pressure pump in a fuel tank, providing fuel inlets at both ends of a delivery pipe, connecting one of the inlets to the discharge side of the low-pressure pump, The inlet is connected to the discharge side of the high-pressure pump, and the connection side of the delivery pipe to the low-pressure pump is connected to the upper end of a passage whose lower end opens to the fuel tank via a high-pressure pressure regulator. And a bypass passage provided with a low-pressure pressure regulator and an electromagnetic switching valve in series.