JP2002013453A - Accumulation type fuel system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To damp pulsation from the first time when generating the pressure pulsation and to have a simple and small constitution as a mechanism for damping the pulsation in an accumulation fuel system. SOLUTION: This accumulation fuel system having a fuel feed pump 1, a common rail 2 being connected to the fuel feed pump 1 via fuel feed passage, and a fuel injection valve 3 being connected to the common rail 2 via the fuel feed passage is provided with a pressure damping valve 20 comprising only a valve mechanism damping the pressure wave propagating from the downstream is provided on the way to fuel feed passages (pipes 12 and 13) from the fuel feed pump 1 to the fuel injection valve 3. The pressure damping valve 20 is constituted of a counterflow throttling valve, which is provided with a valve element being energized against the flowing direction from the upstream to the downstream of the fuel feed passage and an orifice channel having an orifice formed in the valve element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator of the type in which high-pressure fuel supplied from a fuel supply pump is stored in a common rail, and the high-pressure fuel stored in the common rail is supplied to an internal combustion engine via a fuel injection valve. The present invention relates to a fuel supply device.

[0002]

2. Description of the Related Art A fuel supply device of this type temporarily stores fuel supplied via a fuel supply pipe by a fuel supply pump in a common rail as shown in Japanese Patent Application Laid-Open No. Hei 8-21333. The fuel stored in the common rail is supplied to each cylinder via a branch supply pipe from an injection valve provided for each cylinder of the internal combustion engine.

In such a fuel supply device, a fuel supply path (a fuel passage in a fuel supply pipe) connecting the common rail and the injection valve or a fuel supply pump and the common rail are connected due to the operation of the injection valve. A reflected wave is generated in the connected fuel supply path (fuel path in the branch supply pipe), and the pressure pulsation accompanying the reflected wave changes the injection characteristics and makes it difficult to perform accurate injection control. For this reason, since it is necessary to eliminate this inconvenience, the publication discloses that at least one of the fuel supply path connecting the fuel supply pump and the common rail and the fuel supply path connecting the common rail and the injection valve have a resonance. There has been proposed a configuration in which a resonator constituted by a chamber and a neck passage connecting the resonance chamber to a fuel supply path is provided, and the pressure pulsation wave is attenuated by the resonator.

[0004] As a specific mode, the first publication of the publication
As shown in the embodiment, the neck passage is provided so as to be branched from the fuel passage, and the resonance chamber is formed beside the fuel supply passage, or as shown in the second to fourth embodiments, the neck passage is provided. A configuration in which the passage and the resonance chamber are formed as a part of a fuel supply passage has been considered.

[0005]

However, in the above-mentioned accumulator type fuel supply device, the fuel filling the fuel supply passage from the fuel supply pump to the fuel injection valve has a very high pressure, and the above-described pressure pulsation does not occur. It is bigger than expected. According to an experiment by the present inventors, a pressure pulsation of about 30 MPa (about 300 Kgf / cm ² ) occurs in a pressure-accumulation type fuel supply device capable of generating a pressure of 140 MPa (about 1400 Kgf / cm ² ). It has been confirmed that when this pressure pulsation wave reaches the upstream components (fuel supply pump, common rail, etc.) even temporarily, it not only changes the injection characteristics, but also possibly damages these components. There is a risk that it will. Further, if the state in which the pressure wave is propagated in the pipes and the common rails constituting the fuel supply path is repeated, erosion of the inner walls of the pipes and the like is promoted, and there is a disadvantage that the life of the component parts is significantly reduced, When designing piping and the like in anticipation of such erosion, there is a concern that the device itself may be increased in size and cost due to an increase in the thickness of parts.

[0006] In this regard, in the above-mentioned conventional technology, a resonance chamber is provided to reduce pressure pulsation.
In the configuration in which the resonance chamber is branched from the fuel passage,
It is unavoidable that a large pulsation at the initial stage of the generation of the pressure wave is transmitted to the upstream component.
Further, in the configuration in which the resonance chamber is provided on the fuel passage, a configuration that suppresses pressure loss during fuel supply is required, and a configuration that attenuates the pressure pulsation by providing the resonance chamber is large. Becomes

Further, it is necessary to design the volume of the resonance chamber for each of the apparatuses having different fuel supply pipe lengths. In particular, according to the relational expression in the publication, the volume of the resonance chamber is determined by the fuel supply pipe. Path length connecting pump and common rail, or
Since the passage length connecting the common rail and the injection valve becomes longer as the passage length becomes longer, depending on the layout to be mounted on the vehicle, there is an inconvenience that it cannot be designed to a desirable size due to the restriction of the mounting space.

Therefore, in the present invention, in a pressure-accumulation type fuel supply device, the pulsation can be attenuated from the first generation of the pressure pulsation, and the mechanism for attenuating the pulsation is realized with a simple and small configuration. It is an object of the present invention to provide a pressure-accumulation type fuel supply device that can perform pressure reduction.

[0009]

In order to achieve the above object, an accumulator fuel supply device according to the present invention comprises a fuel supply pump, a common rail for storing fuel, and a fuel supply provided for each cylinder of an internal combustion engine. An injection valve, and a high-pressure fuel pressurized by the fuel supply pump can be supplied to the common rail via a fuel supply path connecting the fuel supply pump and the common rail, and the common rail and each of the fuels are provided. The fuel stored in the common rail can be supplied to each fuel injection valve via a fuel supply path connecting the injection valve to the fuel injection valve. Pressure damping means constituted only by a valve mechanism for attenuating a pressure wave propagating from the downstream side in the fuel supply path leading to Section 1).

Therefore, the pressure wave generated in the fuel supply passage due to the operation of the injection valve and the like is attenuated by the pressure damping means provided in the middle of the fuel supply passage. It is possible to attenuate the pressure wave sent upstream from the attenuating means. Further, since the pressure damping means is constituted only by the valve mechanism, it is possible to avoid an increase in the size of the device and to simplify the structure.

Here, the pressure attenuating means includes a valve body urged against the flow direction from the upstream side to the downstream side of the fuel supply passage, and an upstream side of the valve body formed on the valve body. It is practical to use a backflow throttle valve having an orifice passage having an orifice that constantly communicates with the downstream side (claim 2).

According to such a configuration, at the time of fuel supply, the valve is pushed up to send the fuel to the downstream side at once, and when a pressure wave is generated, the valve is closed and the downstream side is passed only through the orifice passage. Is released to the upstream side.
For this reason, the propagation of the pressure wave to the upstream side can be reduced, and the pressure wave can be gradually attenuated by the orifice passage, thereby preventing damage to the components of the accumulator type fuel supply device and increasing the pressure wave. A stable injection characteristic can be maintained without disturbance of the injection characteristic.

In particular, if the pressure attenuating means is provided in the fuel supply path connecting the fuel supply pump and the common rail (claim 3), the transmission of pressure waves propagating from the common rail to the fuel supply pump can be suppressed. It is possible to eliminate the possibility of damage to the fuel supply pump. In addition, when there is a great demand to avoid disturbance of the injection characteristics or damage to the common rail due to the pressure wave generated by the operation of the fuel injection valve, a pressure attenuation means is provided in the fuel supply path connecting the fuel injection valve and the common rail. It may be provided (claim 4). Further, the pressure damping means may be provided in each of a fuel supply path connecting the fuel supply pump and the common rail and in a fuel supply path connecting the common rail and the fuel injection valve. ).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The overall structure of a pressure accumulating fuel supply device according to the present invention will be described below.
As shown in FIG. 1, a fuel supply pump 1 pressurizes and supplies fuel, a common rail 2 for storing fuel, and a fuel injection valve 3 provided for each cylinder of the internal combustion engine.

The fuel supply pump 1 has two plungers (not shown), and a supply pump 4 for pressurizing and feeding the introduced fuel, and a fuel metering for adjusting the amount of fuel oil supplied to the supply pump 4. A unit (FMU) 5 and a feed pump 6 for sucking up fuel and supplying it to the FMU 5 are assembled and configured.
The fuel pipe system of the accumulator type fuel supply device includes a pipe 10 connecting the fuel tank 7 and the feed pump 6, a pipe 11 connecting the feed pump 6 and the FMU 5, a supply pump 4 of the fuel supply pump 1, and the common rail 2. And a pipe 13 connecting the common rail 2 and each fuel injection valve 3.
The fuel oil sucked up by this is supplied to a fuel metering unit (FMU) 5, the amount of fuel oil supplied to the supply pump 4 is adjusted by the FMU 5, and the fuel oil is alternately pressurized by two plungers 4 (not shown). The fuel oil is fed to the common rail 2 under pressure, and fuel is supplied from the common rail 2 to each fuel injection valve 3. Here, a fuel supply path connecting the fuel supply pump 1 and the common rail 2 is formed by the pipe 12, and a fuel supply path connecting the common rail 2 and each fuel injection valve 3 is formed by the pipe 13.

The fuel pipe system of the accumulator type fuel supply device is provided on an overflow valve (not shown) provided on the fuel supply pump 1 and on the common rail 2 so that when the fuel oil pressure in the rail becomes higher than a specified pressure, the fuel pipe system in the rail is opened. The feed pump 6 has a pressure limiting valve 8 for discharging fuel oil, and a pipe 14 for connecting a fuel outlet communicating with a control chamber (not shown) of each fuel injection valve 3 to the fuel tank 7.
To return the fuel oil at a predetermined pressure or higher sent to the supply pump 4 through the FMU 5 to the fuel tank 7 and return the fuel oil at a predetermined pressure or higher in the common rail 2 to the fuel tank 7 to prevent the pressure in the common rail from rising. The high-pressure fuel oil in a control chamber (not shown) of the fuel injection valve 3 is discharged to the fuel tank 7 at the start of injection to open the fuel injection valve 3.

The fuel injection valve 3 is controlled by an electronic control unit (ECU) 14 based on various information signals such as engine speed detected by various sensors and switches (not shown). It operates and injects high-pressure fuel in the common rail at an optimal injection timing and injection amount.

In such an accumulator type fuel supply device,
In this example, a pressure damping valve 20 composed of a backflow throttle valve is provided in the middle of a pipe 12 connecting the fuel supply pump 1 and the common rail 2.

FIG. 2 shows a specific configuration of the pressure damping valve.
The pressure decay valve 20 is connected to a pipe 1 leading to the common rail 2.
2a to which connection body 2a is connected, and this connection body 2
1 and a valve holder 22 to which a pipe 12b communicating with the fuel supply pump 1 is connected and screwed to the fuel supply pump 1.
The coupling body 21 is formed with a through hole 24 having an outlet opening 23 whose diameter is conically increased toward the end face to which the pipe 12a is connected. The through hole 24 is formed in the axial direction. The pipe 12b is connected to the valve holder 22. A through-hole 26 is provided in the axial direction, which is provided with an inlet opening 25 whose diameter increases in a conical shape toward the end face and communicates with the through-hole 24 of the coupling body 21.

In the through hole 26 of the valve holder 22, a region whose diameter is increased on the side opposite to the inlet opening 25, that is, on the side that is screwed with the coupling body 21, is formed. The sheet member 27 and the spacer 28 are fixed by a screw member 29 screwed into the through hole 26 from the side of the coupling body 21.

The seat member 27 is held at its periphery by the valve holder 22, has a through hole 32 formed in the axial direction, and has a seat surface 31 on the spacer-side end surface on which a valve 30 to be described later is seated. .

On the other hand, the spacer 28 is fixed so as to be sandwiched between the seat member 27 and the screw member 29, and a valve housing space 33 is formed between the spacer 28 and the seat member 27. The valve element 30 is housed in the element 33.

The spacer 28 has a notch 34 formed by cutting a peripheral wall in an axial direction from a contact surface with the valve holder, and a stopper 35 for restricting the lift of the valve body 30 is formed. Have been. This stopper portion 35
Is formed so that the inner wall surface of the spacer 28 protrudes inward, and the distance from the sheet member 27 to the stopper portion 35 is shorter than the axial dimension of the cutout portion 34.

The valve element 30 is accommodated in the valve element accommodating space 33 so as to cover the through hole 32 of the seat member 27 and to allow movement in the axial direction. It is constantly urged in the contact direction. The spring 41 is disposed so as to pass through a through hole 40 formed in the spacer 28, and
9, a spring receiving portion 38 formed by reducing the diameter in the middle of an axial through hole 37, and a valve body 30.
Step 39 formed by reducing the diameter of the side opposite to the side facing the sheet surface 31 to the small diameter section 30a
It is armed between. The stopper portion 35 comes into contact with the step portion 39 when the valve body 30 is lifted, and the small-diameter portion 30a of the valve body 30 has a small diameter portion 30a even if a spring is interposed between the small hole 30a and the through hole 40 of the spacer 28. The diameter is formed such that a sufficient gap is formed. Also, the valve body 30
An orifice passage 42 having an orifice is formed at the center thereof so as to penetrate in the axial direction.

Therefore, when the valve body 30 is in contact with the stopper 35, the notch 3 is provided beside the valve body 30.
4 forms an oil feed passage 36 that connects the through hole 32 of the sheet member 27 and the through hole 37 of the screw member 29. When the valve body 30 is seated on the seat surface 31 of the seat member 27, the through hole 32 of the seat member 27 and the through hole 37 of the screw member 29 communicate with each other only through the orifice passage 42.

In the above configuration, when fuel is supplied from the fuel supply pump 1 to the common rail 2, FIG.
As shown in FIG. 5, the high pressure fuel sent from the fuel supply pump 1 causes the valve body 30 to lift against the spring force and abut against the stopper 35 of the spacer 28, thereby forming an oil feed formed beside the valve body 30. The fuel flows from the through hole 32 of the sheet member 27 to the through hole 37 of the screw member 29 through the passage 36, and is sent to the common rail 2. Then, from the common rail 2 side (downstream side) to the fuel supply pump 1 side (upstream side)
As shown in FIG. 3B, the valve body 30 is seated on the seat surface 31 and the fuel flows from the downstream side to the upstream side only through the orifice passage 42 as shown in FIG. .

For this reason, the reflected wave from the common rail 2 toward the fuel supply pump 1 escapes toward the fuel supply pump only through the orifice passage 42, and is reflected from the common rail 2 toward the fuel supply pump 1. Waves can be blocked by the pressure damping valve 20. At this time, the reflected wave is reflected by the pressure attenuation valve 20 and tends to propagate toward the common rail.
Of the reflected wave reaching the orifice passage 42
The pressure is attenuated by the pressure attenuating valve 20 through the pipe 12b on the upstream side through the valve.

Therefore, the reflected wave generated by the operation of the fuel injection valve 3 is rapidly attenuated by the pressure damping valve 20 provided in the middle of the pipe, and the pressure wave reaching the fuel supply pump 1 passes through the orifice passage 42. Since the leak is very small, the fuel supply pump 1 can be prevented from being damaged due to the pressure pulsation, and the pressure pulsation in the pipe can be rapidly attenuated to suppress the erosion of the pipe due to the pressure pulsation. And the durability of the piping is not impaired.

In the above-described configuration example, an example is shown in which the pressure damping valve 20 composed of the backflow throttle valve is provided in the pipe 12 connecting the fuel supply pump 1 and the common rail 2. , The position indicated by the dashed line in FIG.
A pressure damping valve 20 similar to the above may be provided in the middle of the pipe 12 connecting the fuel injection valve 3 and the common rail 2. Such a configuration is particularly useful when the common rail 2 is physically susceptible to pressure waves or when there is a strong demand to avoid the disadvantage that the injection characteristics are affected by the propagation of the pressure waves into the common rail. It is effective for Further, if necessary, the pressure damping valve 20 may be provided both in the middle of the pipe 12 connecting the fuel supply pump 1 and the common rail 2 and in the middle of the pipe 13 connecting the fuel injection valve 3 and the common rail 2. It may be.

[0030]

As described above, according to the present invention,
Since a pressure damping means including only a valve mechanism for attenuating a pressure wave propagating from the downstream side is provided in the fuel supply path from the fuel supply pump to the fuel injection valve of the accumulator type fuel supply device, the fuel injection is performed. Pressure waves generated in the fuel supply path due to valve operation etc. can be rapidly attenuated, and pressure waves sent upstream from the pressure attenuating means from the first time the pressure waves are generated can be reliably attenuated. it can.

As a result, stable injection characteristics can be obtained, and the fuel supply pump and the common rail can be damaged by pressure pulsation, and erosion of piping and the like caused by pressure pulsation can be suppressed, and the life of components can be reduced. Can be lengthened. Therefore, it is not necessary to change the design so as to increase the pressure resistance on the premise of the pressure pulsation, and the reliability of the current accumulator type fuel supply device can be improved.
Further, since the pressure damping means itself is constituted only by the valve mechanism, the size of the pressure damping means can be reduced, so that it can be easily mounted on a vehicle regardless of the layout of the fuel supply path. Become.

As the pressure attenuating means, a valve body seated on the seat portion against the flow direction from the upstream side to the downstream side of the fuel supply passage, and the upstream side and the downstream side of the valve body formed on the valve body And an orifice passage that constantly communicates with the backflow throttle valve.
In addition to suppressing the pressure loss during fuel supply, the pressure wave does not propagate to the upstream side at once, so that the components on the upstream side can be protected, and the pressure wave gradually moves to the upstream side by the orifice passage. Since the pressure pulsation is released and attenuated, the pressure pulsation can be effectively attenuated.

The pressure attenuating means may be provided in the middle of a fuel supply path connecting the fuel supply pump and the common rail. In this case, the risk of damage to the fuel supply pump is reduced. An accumulator-type fuel supply device emphasizing protection of the fuel supply pump can be provided. Further, a pressure damping means may be provided in the fuel supply path connecting the fuel injection valve and the common rail. In this case, the pressure-accumulation type fuel supply system emphasizing the stability of the injection characteristics and the protection of the common rail. An apparatus can be provided. Further, if the pressure attenuating means is provided in each of the fuel supply path connecting the fuel supply pump and the common rail, and in the fuel supply path connecting the common rail and the fuel injection valve, the fuel supply pump and the fuel supply pump are provided. While protecting both the common rail and the common rail, it is possible to stabilize the injection characteristics and reduce the erosion of the piping constituting each fuel supply passage.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a fuel system of an accumulator-type fuel supply device according to the present invention.

FIG. 2 is a cross-sectional view showing a specific configuration example of a pressure damping valve.

FIG. 3 is a diagram for explaining the operation of the pressure damping valve shown in FIG. 2, and FIG. 3 (a) shows a state during fuel supply;
FIG. 3B shows a state in which the valve body is seated on the seat part by the reflected wave.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel supply pump 2 Common rail 3 Fuel injection valve 12 Piping 20 Pressure damping valve 30 Valve element 31 Seat part 42 Orifice passage

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 37/00 311 F02M 37/00 311A (72) Inventor Kotaro Tatsuzaki 3-13-26 Yayumicho, Higashimatsuyama-shi, Saitama 3G066 AA07 AB02 AC01 AC09 AD12 BA12 BA38 BA67 CB01 CB08T CB09 CB11 CB12 CC01 CE13

Claims (5)

[Claims] 1. A fuel supply pump, a common rail for accumulating fuel, and a fuel injection valve provided for each cylinder of an internal combustion engine, wherein a fuel supply passage connecting the fuel supply pump and the common rail is provided. High-pressure fuel pressurized by the fuel supply pump can be supplied to the common rail, and the fuel stored in the common rail is injected into each fuel via a fuel supply path connecting the common rail and each of the fuel injection valves. In a pressure accumulating fuel supply device capable of supplying a valve, a pressure attenuation constituted only by a valve mechanism that attenuates a pressure wave propagating from a downstream side in the fuel supply path from the fuel supply pump to the fuel injection valve. An accumulator type fuel supply device characterized by comprising means. 2. The valve according to claim 1, wherein the pressure attenuating means includes a valve body urged against a flow direction from an upstream side to a downstream side of the fuel supply passage, and an upstream side of the valve body formed on the valve body. The accumulator-type fuel supply device according to claim 1, further comprising a backflow throttle valve having an orifice passage having an orifice constantly communicating with a downstream side. 3. The accumulator type fuel supply device according to claim 1, wherein the pressure attenuation means is provided in a fuel supply passage connecting the fuel supply pump and the common rail. 4. The accumulator type fuel supply device according to claim 1, wherein the pressure damping means is provided in a fuel supply passage connecting the common rail and the fuel injection valve. 5. The pressure reducing means is provided in each of a fuel supply passage connecting the fuel supply pump and the common rail and a fuel supply passage connecting the common rail and the fuel injection valve. The accumulator type fuel supply device according to claim 1 or 2, wherein the pressure storage type fuel supply device is provided.