JP3183203B2 - High pressure fuel injection system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure fuel injection device for an internal combustion engine that injects high-pressure fuel from a high-pressure fuel pump to the internal combustion engine.

[0002]

2. Description of the Related Art As a device for supplying high-pressure fuel to an internal combustion engine, a device having a high-pressure fuel pump for pressurizing fuel supplied to the engine is generally used (for example, Japanese Patent Application Laid-Open No. HEI 8-112281). "Fuel injection device" described in the gazette).

[0003] As shown in FIG. 3, the high-pressure fuel injection device 100 described in this publication includes a high-pressure supply pump 111, which is provided with a cylinder 120 and a plunger 121 provided in the cylinder 120 so as to be able to reciprocate. And a pump chamber 122 defined by a cylinder 120 and a plunger 121. This plunger 121
It moves up and down with rotation of a crankshaft (not shown) of the engine 115.

[0004] The opening 122a of the pump chamber 122 is provided with an electromagnetic valve 1 provided above the cylinder 120 (upper part in the figure).
It is opened and closed by 41 valve bodies 141a. This solenoid valve 14
Reference numeral 1 denotes an electronic control unit (EC) (not shown) of the engine 115.
U) is controlled to be energized.

The opening 122a is connected to the low-pressure passage 143, the pipe 1
30 and the fuel tank 11 via the low pressure supply pump 114
3 is connected. The low-pressure supply pump 114 sucks the fuel in the fuel tank 113 and pumps the fuel toward the pump chamber 122 side. The pump chamber 122 is connected to a common rail 155 by a pipe 135 provided with a check valve 136.

[0006] A plurality of injectors 156 are provided on the common rail 155 corresponding to each cylinder of the engine 115, and the fuel in the rail 155 is supplied to the injector 156.
From the combustion chamber of each cylinder. The common rail 155 is provided with a pressure sensor 161 for detecting the pressure in the rail 155 and outputting a signal to an electronic control unit (not shown).

In the above-described apparatus 100, when the solenoid valve 141 is opened, the plunger 121 moves down in the cylinder 120, so that the fuel pumped from the supply pump 114 is supplied into the pump chamber 122 through the pipe 130 and the low-pressure passage 143. Introduced via

When the solenoid valve 141 is closed after the introduction of the fuel, the fuel in the pump chamber 122 is released from the plunger 121.
Pressurized with the upward movement. Then, when the fuel pressure in the pump chamber 122 rises above the valve opening pressure of the check valve 136, the valve 136 opens, and fuel is pumped into the common rail 155 through the pipe 135.

In the apparatus 100, the amount of fuel pumped from the pump chamber 122 into the common rail 155 can be adjusted by controlling the closing timing of the solenoid valve 141 by the electronic control unit. That is, the electronic control unit controls the closing timing of the solenoid valve 141 based on information obtained from a cam angle sensor disposed on a crankshaft (not shown) of the engine 115, so that the pressurization start timing is determined, and The amount of fuel discharged has been adjusted. For example, when the solenoid valve 141 is closed simultaneously with the upward movement of the plunger 121, all the fuel introduced into the pump chamber 122 is pressurized and discharged, and in this case, the amount of fuel discharged from the device to the common rail 155 Is the maximum discharge amount.

As described above, according to the device 100, the fuel pressure in the common rail 155 can be maintained at a predetermined value by changing the opening / closing timing of the solenoid valve 141 to change the fuel discharge amount.

[0011]

According to the high-pressure fuel injection device 100, the fuel is temporarily stored in the common rail 155 and then the stored fuel is fed to the injector 156.
In particular, immediately after the start of the engine, each of the pumps 111 and 114 draws fuel from the fuel tank 113 by the rotation of a starter (not shown), and sends the fuel to the common rail 155 for a period until the fuel reaches a predetermined pressure.
Cannot perform fuel injection. For this reason, there is a problem in that the engine startability from immediately after the start of the engine start until the fuel on the common rail 155 reaches the predetermined pressure is reduced.

Therefore, in the device described in the publication, the driving of the low-pressure supply pump 114 is started at the stage when the start of the engine 115 is foreseen, such as when the ignition switch is turned on, and the fuel pressure of the common rail 155 decreases During the period in which the supply pressure is lower than the discharge pressure of the supply pump 114, measures are taken such as driving the low-pressure supply pump 114 at the maximum capacity.

However, if the deterioration of the engine startability is eliminated in such a manner, the control at the time of starting the engine becomes complicated, and the calculation load for the control is increased, which is not preferable.

On the other hand, as a countermeasure against such a decrease in startability,
The publication also describes that a bypass pipe 130a capable of pressure-feeding pressurized fuel from the low-pressure supply pump 114 to the common rail 155 directly is provided by bypassing the high-pressure supply pump 111, as shown by a broken line in FIG. Have been.
A check valve 131 is provided in the bypass pipe 130a to prevent the fuel from flowing back from the common rail 155.

By providing such a bypass pipe 130a, pressurized fuel pumped from the low-pressure supply pump 114 is supplied to the bypass pipe 13a at the start of engine start.
Thus, the power is directly supplied to the common rail 155 via Oa, so that the startability of the engine can be compensated for without any complicated control.

However, in this case, the bypass pipe 13
In addition to being restricted by the space due to the provision of Oa, the piping structure is complicated, and the problem still remains practically.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine capable of eliminating a decrease in engine startability without requiring complicated control and a complicated piping structure. To provide a high-pressure fuel injection device.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the first aspect of the present invention, a high-pressure fuel pump for pressurizing fuel delivered from a fuel tank to a high pressure and discharging the fuel is provided. A fuel distribution pipe for supplying fuel to the internal combustion engine,
A first check valve provided between the fuel distribution pipe and the high-pressure fuel pump to prevent backflow of fuel;
Provided in the fuel pressure path to the pump to prevent fuel backflow
In high-pressure fuel injection system for an internal combustion engine equipped with a second check valve that, fuel is pumped to the high pressure fuel pump the sum of the opening pressure of the first and second check valve from the fuel tank The gist is that the pressure is set lower than the pressure.

[0019]

[0020]

According to the above configuration, the fuel pressure fed from the fuel tank to the high-pressure fuel pump via the second check valve is equal to the valve opening pressure of the first and second check valves. Since the sum is larger than the sum, even when the engine is started, the fuel is quickly supplied from the fuel tank to the fuel distribution pipe. As a result, the startability of the internal combustion engine can be suitably improved without performing any complicated control or separately providing a bypass pipe or the like.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment in which the present invention is embodied in a high-pressure fuel injection device for a gasoline engine for a vehicle will be described below.

FIG. 1 shows a schematic configuration of a high-pressure fuel injection device 10 according to this embodiment. The high-pressure fuel injection device 10 includes a high-pressure fuel pump 11, a spill valve 41, a fuel tank 13, a low-pressure feed pump 14, and the like. The high-pressure fuel pump 11 pressurizes the fuel to a high pressure, and is formed by a cylinder 20, a plunger 21 reciprocating in the cylinder 20, an inner peripheral wall surface of the cylinder 20, and an upper end surface of the plunger 21. Pressurizing chamber 2
2 is provided.

A tappet 23 attached to the lower end (lower end in the figure) of the plunger 21 is pressed against a cam 25 provided on a crankshaft 24 of the engine 15 by the urging force of a spring (not shown). When the cam 25 rotates with the rotation of the crankshaft 24, the plunger 21 reciprocates in the cylinder 20 and the pressure chamber 22
The volume inside changes.

The pressurizing chamber 22 is connected to the fuel tank 13 by an inflow passage 30. The inflow passage 30 is provided with a low-pressure feed pump 14 and a fuel filter 32. The fuel in the fuel tank 13 is sucked and discharged by the low-pressure feed pump 14. The low-pressure feed pump 14 is electrically controlled by an electronic control unit (ECU) 60 of the engine 15. Further, impurities mixed in the fuel are removed by the fuel filter 32.

The discharged fuel flows through the inflow passage 30 and is introduced into the pressurizing chamber 22 through the spill valve 41. The housing (not shown) of the spill valve 41 is fixed to the high-pressure fuel pump 11. The spill valve 41 is an electromagnetic valve, and is controlled by energizing the solenoid coil 45 by the ECU 60 and exciting a stator (not shown). That is, when the stator is not excited in the spill valve 41, the valve element 47 is separated from the opening 22a of the pressurizing chamber 22 by the urging force of the spring 49, and thus the spill valve 41 is always in the open state. .

On the other hand, when the stator is excited by the solenoid coil 45, the armature 48
Is sucked by the stator. As a result, the armature 48 moves to the stator side against the urging force of the spring 49,
By this movement, the valve body 47 closes the opening 22a and the spill valve 41 is closed.

A portion of the inflow passage 30 between the low-pressure feed pump 14 and the fuel filter 32 is connected to the fuel tank 13 by a relief passage 33.
A relief valve 34 is provided in the middle of the relief passage 33. The relief valve 34 opens when the fuel pressure in the inflow passage 30 between the low-pressure feed pump 14 and the fuel filter 32 exceeds a predetermined value. . By opening the relief valve 34, the fuel in the inflow passage 30 is returned to the fuel tank 13 through the relief passage 33. As a result, the pressure of the fuel transferred from the low-pressure feed pump 14 to the fuel filter 32 is maintained substantially constant.

A pressure regulator 50 is provided in the spill passage 39 between the spill valve 41 and the fuel tank 13.
The pressure chamber 2 is provided by the regulator 50.
The fuel pressure going to 2 is kept constant. Moreover, in the present embodiment, the fuel pressure is controlled by a check valve 36 described later.
Is set to a value larger than the valve opening pressure.

The pressurizing chamber 22 is connected by a supply passage 35 to a fuel distribution pipe (common rail) 55 provided in the engine 15. The fuel distribution pipe 55 is for maintaining the fuel at a high pressure and distributing the fuel to an injector 56 described later.

The engine 15 is provided with a plurality of injectors 56 corresponding to each cylinder. Each injector 56 is connected to a fuel distribution pipe 55, respectively.
The high-pressure fuel in the same pipe 55 is distributed and supplied to the injector 56.

The supply passage 35 is provided with a check valve 36 which allows only the flow of fuel from the pressurizing chamber 22 to the fuel distribution pipe 55.
5 is restricted from flowing back to the pressurizing chamber 22.

Further, the fuel distribution pipe 55 is connected to the fuel tank 13 by a relief passage 38 provided with a relief valve 37 on the way. When the fuel pressure in the fuel distribution pipe 55 rises to a predetermined value or more, the relief valve 37 is opened, and the fuel in the distribution pipe 55 is returned to the fuel tank 13 through the relief passage 38. This allows
Excessive fuel pressure in the fuel distribution pipe 55 is prevented.

The injector 56 is an ECU of the engine 15.
By opening and closing based on the signal from 60, a predetermined amount of fuel is injected and supplied to each cylinder of the engine 15.
A fuel pressure sensor 61 is attached to the fuel distribution pipe 55. The fuel pressure sensor 61 detects a fuel pressure in the fuel distribution pipe 55 and outputs a signal corresponding to the pressure to the ECU 60. The ECU 60 includes a CP (not shown).
It comprises a microcomputer having a U, a RAM, a ROM, an IO port and the like.

Next, the operation of the high-pressure fuel injection device of the present embodiment configured as described above will be described. When an ignition switch (not shown) is turned on and power is supplied to the ECU 60, the low-pressure feed pump 14 is driven by a command from the ECU 60. The pump 14 sucks fuel from the fuel tank 13, pressurizes the fuel to a predetermined pressure, and sends the fuel to the spill valve 41 through the inflow passage 30.

At this time, since the stator is not yet excited by the solenoid coil 45 and the spill valve 41 is always open, the fuel pressure-fed to the spill valve 41 reaches the pressurizing chamber 22. . In addition, since the pressure of the fuel is higher than the opening pressure of the check valve 36 as described above, the check valve 36 is opened by the fuel pressure, and the fuel is quickly supplied to the fuel distribution pipe 55 through the supply passage 35. Pumped. Therefore, before the engine 15 is started, the inside of the fuel distribution pipe 55 is filled with fuel having an injection pressure necessary for starting the engine 15.

Next, when an engine starter switch (not shown) is turned on, as described above, the fuel distribution pipe 5 is already turned on.
5 is filled with fuel having an injection pressure necessary for starting the engine 15, so that the engine 15 starts a good start.

When the operation of the engine 15 is started, the cam 25 rotates along with the crankshaft 24, so that the plunger 21 reciprocates up and down in the cylinder 20. Then, the fuel in the fuel tank 13, which is pressure-fed into the inflow passage 30 from the low-pressure feed pump 14, starts to move downward from the top dead center at the same time as the plunger 21 starts to move downward from the top dead center. 22. At this time, the solenoid coil 45 of the spill valve 41
The CU 60 has not yet been energized, and the valve 41 is in an open state.

Next, the plunger 21 starts to move upward from the bottom dead center. At this time, when the spill valve 41 is open, a part of the fuel in the pressurizing chamber 22 overflows into the spill passage 39 and passes through the fuel tank 1 through the pressure regulator 50.
As a result, the entire fuel in the pressurizing chamber 22 is not pumped into the fuel distribution pipe 55.

On the other hand, when the spill valve 41 is closed, the fuel in the pressurizing chamber 22 is pressurized. The pressurized fuel is supplied to the supply passage 3 through the check valve 36.
5 is fed to the fuel distribution pipe 55 by pressure.

Then, the ECU 60 starts closing the spill valve 41, that is, energizes the solenoid coil 45, so that the fuel pressure in the fuel distribution pipe 55 detected by the fuel pressure sensor 61 becomes a predetermined pressure. The timing is adjusted to control the amount of fuel pumped into the fuel distribution pipe 55.

The effects obtained by the above-described embodiment will be described below. In the high-pressure fuel supply device 10 according to this embodiment, the fuel tank 13 is
When the engine 15 is started to start, the plunger 2
The fuel is immediately supplied to the fuel distribution pipe 55 without performing the operation of (1). Therefore, without any complicated control,
In addition, even if bypass pipes are not separately provided, the engine 15
Startability can be improved.

[Second Embodiment] Next, a second embodiment of the present invention will be described, focusing on differences from the first embodiment. In the description of the second embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 2 shows a schematic configuration of the high-pressure fuel injection device 10 according to the present embodiment. The configuration of the present embodiment differs from the configuration of the first embodiment in that a check valve 31 is disposed at the position of the spill valve 41 and the spill valve 41 is disposed downstream of the pressurizing chamber 22. ing.

In the high-pressure fuel injection device 10, the pressurizing chamber 22 is connected to the fuel tank 13 by an inflow passage 30, and the inflow passage 30 has a low-pressure feed pump 14, a fuel filter 32, and a check valve 31 ( (A second check valve). The check valve 31 is connected to the inflow passage 30.
Only the flow of fuel from the low-pressure feed pump 14 to the pressurizing chamber 22 is allowed.

A spill passage 39 between the check valve 31 and the fuel tank 13 is provided with a pressure regulator 50. In the present embodiment, the pressure of the fuel which is fed from the low-pressure feed pump 14 toward the check valve 31 by the regulator 50 is adjusted to the valve opening pressure of the check valve 31 by the check valve 36 ( It is kept constant as a value larger than the value obtained by adding the valve opening pressure of the first check valve.

The pressurizing chamber 22 is connected to the fuel tank 13 by a spill passage 39 whose part connected to the same chamber 22 is common to the supply passage 35. A spill valve 41 is provided in the middle of the spill passage 39. The spill valve 41 is an electromagnetic valve, and is controlled by energizing the solenoid coil 45 by the ECU 60 and exciting a stator (not shown). That is, the spill valve 41
When the stator is not energized, the valve body 47 is separated from the valve seat 46 by the urging force of the spring 49, so that the valve 41 is always open. On the other hand, when the stator is excited by the solenoid coil 45, the armature 48 is attracted to the stator. As a result, the armature 48 moves toward the stator against the urging force of the spring 49, and this movement causes the valve body 4 to move.
7 is seated on the valve seat 46 and the spill valve 41 is closed.

In the spill passage 39 downstream of the spill valve 41, the backflow of fuel from the fuel tank 13 to the spill valve 41 is restricted, and the fuel pressure in the passage becomes equal to or higher than a predetermined pressure. A pressure regulating valve 40 is provided which is opened at this time.

Next, the operation of the high-pressure fuel injection device of the present embodiment configured as described above will be described. When an ignition switch (not shown) is turned on and power is supplied to the ECU 60, the low-pressure feed pump 14 is driven by a command from the ECU 60, and the solenoid coil 45
, And the stator is excited. And the same pump 1
4 sucks the fuel from the fuel tank 13, pressurizes the fuel to a predetermined pressure, and sends the fuel to the check valve 31 via the inflow passage 30.

At this time, as described above, since the fuel pressure is higher than the valve opening pressure of the check valve 31, the check valve 31 is opened.
The fuel reaches the pressure chamber 22. Further, since the stator is excited by the solenoid coil 45 and the spill valve 41 is in the closed state, the fuel in the pressurizing chamber 22 is supplied to the check valve 3.
Go only to 6. Moreover, the pressure of this fuel is
(As described above, the fuel tank 13
Is higher than the sum of the valve opening pressure of the check valve 31 and the valve opening pressure of the check valve 36, the fuel pressure in the pressurizing chamber 22 is , Check valve 36
), The check valve 36 is opened by this fuel pressure, and the fuel is quickly pumped to the fuel distribution pipe 55 through the supply passage 35. Therefore, engine 1
Before the start of the engine 5, the inside of the fuel distribution pipe 55 is filled with fuel having an injection pressure required for starting the engine 15.

Next, when the engine starter switch is turned on, as described above, the inside of the fuel distribution pipe 55 is already filled with the fuel having the injection pressure necessary for starting the engine 15, so that the engine 15 starts a good start. Start.

When an engine starter switch (not shown) is turned on, the ECU 60 switches the solenoid coil 45
Stop supplying power to Next, when the operation of the engine 15 is started, the cam 25 rotates along with the crankshaft 24, so that the plunger 21 reciprocates vertically in the cylinder 20. And the low pressure feed pump 1
The fuel in the fuel tank 13 that has been pressure-fed into the inflow passage 30 from 4 is introduced into the pressurizing chamber 22 via the check valve 31 at the same time that the plunger 21 starts to move down from the top dead center. At this time, the solenoid coil 45 of the spill valve 41 is connected to the ECU 6
0 indicates that no current is supplied, and the valve 41 is in an open state.

Next, the plunger 21 starts to move upward from the bottom dead center. At this time, when the spill valve 41 is open, a part of the fuel in the pressurizing chamber 22 overflows the spill passage 39 and returns to the fuel tank 13. On the other hand, when the spill valve 41 is closed, the fuel in the pressurizing chamber 22 is pressurized. Then, the pressurized fuel is pumped to the fuel distribution pipe 55 through the check valve 36 and the supply passage 35.

As described above, also in this embodiment, the fuel pressure fed from the fuel tank 13 to the check valve 31 is obtained by adding the valve opening pressure of the check valve 36 to the valve opening pressure of the check valve 31. Therefore, when the engine 15 starts to be started, the fuel is quickly supplied to the fuel distribution pipe 55 without the operation of the plunger 21. Therefore, the startability of the engine 15 can be improved without performing any complicated control and without separately providing a bypass pipe or the like.

Each of the above embodiments can be embodied by changing the configuration as in another embodiment described below. In these other embodiments, substantially the same operation and effects as those of the above embodiments can be obtained.

(A) In each of the above embodiments, the configuration is such that the drive of the low-pressure feed pump 14 is started in response to a command from the ECU 60 upon turning on the ignition switch.
It is not limited to this.

For example, a switch different from the ignition switch may be provided so that the driving of the low-pressure feed pump 14 is started. (B) In each of the above embodiments, the driving of the low-pressure feed pump 14 is performed according to a command from the ECU 60. However, the present invention is not limited to this. For example, a predetermined drive voltage may be supplied directly from the battery when the ignition switch is turned on.

(C) In each of the above embodiments, the present invention is applied to a high-pressure fuel injection device
However, the present invention is applicable to, for example, a diesel engine, and is not limited to a vehicle, and may be applied to a stationary power engine.

(D) In the second embodiment, the portions connected to the pressurizing chamber 22 in the supply passage 35 and the spill passage 39 are common, but each passage 35 and 39 is May be connected separately.

(E) In the above embodiments, the spill valve 41
Although a normally-open solenoid valve is used as the above, a normally-closed solenoid valve may be employed.

[0061]

According to the first aspect of the present invention, in the high-pressure fuel injection device for an internal combustion engine, fuel is quickly supplied to the fuel distribution pipe even when the engine is started. Therefore, the startability of the internal combustion engine can be improved without performing any complicated control and without providing a separate bypass pipe or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a high-pressure fuel injection device according to a first embodiment.

FIG. 2 is a schematic configuration diagram illustrating a high-pressure fuel injection device according to a second embodiment.

FIG. 3 is a schematic configuration diagram showing an example of a fuel injection device according to a conventional technique.

[Explanation of symbols]

11 high-pressure fuel pump, 13 fuel tank, 15 engine, 30 inflow passage, 31, 36 check valve, 35 supply passage, 50 pressure regulator, 55 fuel distribution pipe (common rail).

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 37/00 F02M 37/00 311

Claims (1)

(57) [Claims] 1. A high-pressure fuel pump for pressurizing fuel discharged from a fuel tank to a high pressure and discharging the fuel, a fuel distribution pipe for supplying the discharged fuel to an internal combustion engine, the fuel distribution pipe and the high-pressure fuel pump. A first check valve provided between the first and second pumps to prevent a backflow of fuel;
A high-pressure fuel injection device for an internal combustion engine, comprising: a second check valve provided in a feed path to prevent a backflow of fuel; wherein a sum of valve opening pressures of the first and second check valves is determined by the fuel A high-pressure fuel injection device for an internal combustion engine, wherein the pressure is set to be lower than the fuel pressure fed from the tank to the high-pressure fuel pump.