JPH09177628A - Pressure control valve for fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the delivery pressure of a fuel pump variable in multimodes in response to engine revolutions in such a way that its delivery pressure (injection pressure) is enhanced in a range of high engine revolutions and the like, and let the aforesaid performance be adjusted to the required characteristics of an engine, and thereby contribute toward the enhancement of engine output and the improvement of fuel consumption and exhaust gas characteristics. SOLUTION: It is noted that pressure adjusting springs should be increased in number, namely, the control valve is provided with a pressure adjusting valve body 19 which is lifted up from a seat part (valve seat member 18) upon receiving fuel pressure, and with pressure adjusting springs energizing the pressure adjusting valve body 19 in the seating direction, and in this case, a plurality of the pressure adjusting springs (a first pressure adjusting spring 13 and a second pressure adjusting spring 32) are thereby provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve of a fuel pump, and more particularly to a pressure control valve of a fuel pump such as a cylinder injection type high pressure fuel pump for directly injecting fuel (eg, gasoline) into an engine cylinder. It is about.

[0002]

2. Description of the Related Art A fuel pump in a high-pressure fuel injection system such as a conventional gasoline in-cylinder injection system has a high-pressure fuel pump and a pressure control valve for controlling the fuel pressure. The fuel pump for the high-pressure fuel injection device is proposed in, for example, Japanese Patent Application No. 6-330342 by the present applicant. An outline will be given based on FIG.

FIG. 18 is a schematic overall view of a fuel pump 1 for a high-pressure fuel injection device, and particularly shows a detailed view of a solenoid valve unit 2 portion thereof. The fuel pump 1 for a high-pressure fuel injection device includes a fuel tank 3 and a low-pressure feed pump 4 (low-pressure fuel pump) driven by an electric motor.
And a high-pressure gasoline pump 5 (high-pressure fuel pump) such as a radial piston pump driven by the engine, and a solenoid valve unit 2, and supplies fuel (for example, gasoline) to the injector 7 via the common rail 6.

The solenoid valve unit 2 includes a solenoid valve 9 and a high pressure control valve 10 (high pressure regulator) in a unit housing portion 8.
And.

In the unit housing portion 8, a high pressure side introduction port 11 and a high pressure side passage 12, a low pressure side discharge port 13 and a low pressure side passage 14 (fuel return passage) are formed, and the high pressure side passage 12 and the low pressure side passage 14 are formed. A high pressure control valve 10 and a solenoid valve 9 are provided in parallel so as to straddle them.

The high-pressure gasoline pump 5 supplies high-pressure fuel to the common rail 6 and the injector 7 via the high-pressure fuel supply pipe 15, and the high-pressure fuel control pipe 16 from the common rail 6 to the common rail 6
Is supplied to the high pressure side introduction port 11 of the solenoid valve unit 2, and the low pressure side passage 14 (fuel return passage) is passed through the high pressure control valve 10 and the solenoid valve 9.
The low pressure fuel is circulated to the fuel tank 3 via the low pressure side outlet port 13.

The high pressure control valve 10 includes a valve housing 17, a valve seat member 18, a pressure adjusting valve body 19,
Seat housing 20 and pressure adjusting spring 21
(Regulator spring).

When the pressure from the high pressure side introduction port 11 becomes excessively high, the pressure adjusting valve body 19 resists the urging force of the pressure adjusting spring 21 from the seat portion, that is, the valve seat member 18. Lift and adjust valve body 19
An opening / closing passage 22 (phantom line in the drawing) that connects the high-pressure side passage 12 and the low-pressure side passage 14 can be formed between the valve seat member 18 and the valve seat member 18.

The solenoid valve 9 has an armature 23.
A spring seat member 24, a solenoid spring 25, a solenoid 26, and a valve seat member 27.
And a valve body 28 integrally formed at the tip of the armature 23. The valve body 28 opens and closes an orifice 29 portion communicating with the high pressure side passage 12.

The solenoid valve 9 is "opened" between the high pressure side passage 12 and the low pressure side passage 14 by turning the solenoid 26 "ON" at the time of starting the engine (not shown). Instead of enabling low-pressure fuel to be fed from the low-pressure feed pump 4, starting with low-pressure fuel is possible, and during normal high-pressure operation after the engine is completely decompressed, the solenoid 26 is turned "OFF" so that the high-pressure side passage When the space between the low pressure side passage 12 and the low pressure side passage 14 is “closed”, high pressure injection using the high pressure gasoline pump 5 is performed, but since it is not directly related to the present invention, further detailed description is omitted. To do.

In the fuel pump 1 for a high-pressure fuel injector having such a structure, after the engine is completely exploded, the high-pressure gasoline pump 5 in the normal operation state sucks and discharges fuel, and the common rail 6 and the common rail 6 via the high-pressure fuel supply pipe 15. Fuel is pressure-fed to the injector 7.

However, in the fuel pump 1 for a high-pressure fuel injection device as described above, the characteristic of the high-pressure control valve 10 is set by one pressure adjusting spring 21. That is, since the fuel pressure from the common rail 6 (the discharge pressure Ph from the injector 7) is controlled by the setting force of the pressure adjusting spring 21 and the spring constant, the discharge relative to the engine speed Np (or pump speed) is controlled. There is a limit to making the characteristic of the pressure Ph variable in the low rotation region and the high rotation region of the engine.

That is, as shown in FIG. 19, generally, the discharge pressure Ph increases linearly as the engine speed Np increases. Further, it is possible to control the discharge pressure Ph to move up and down in parallel by setting the inclination gradient by the spring constant of the pressure adjusting spring 21 and selecting the setting force.

However, in the high rotation region of the engine, it is necessary to inject (in the vicinity of 180 degrees at the cam angle) in the compression process by the piston (not shown), and the injection time from the injector 7 is limited. In addition, there is a problem that it is difficult to obtain the fuel injection amount according to the target. On the contrary, if the fuel injection amount is set to the target value in the high rotation speed region, there is a problem that it is difficult to control the fuel injection amount in the low rotation speed region such as idling because the injection amount is too large. Therefore, there is a problem in that a compromise setting must be made to match either rotation region.

Further, FIG. 20 is a graph showing the relationship of the discharge pressure Ph with respect to the engine speed Np similarly to FIG. 19, and the required amount is large when the required amount of the fuel injection amount required by the engine is small. There is a problem that the discharge pressure Ph becomes relatively high with respect to time. That is, (flow rate flowing through the high-pressure pressure control valve 10) = (discharge amount of the high-pressure gasoline pump 5)-(injection amount of the injector 7) (hereinafter, referred to as formula (1)), and therefore the injection amount of the injector 7, In a high rotation region where the required amount of the engine is large, the fuel flow rate to the high pressure control valve 10 is reduced and the lift of the pressure adjusting valve body 19 is small (the spring force of the pressure adjusting spring 21 is small).
There is a problem that the discharge pressure Ph is relatively lowered. Therefore, even if an attempt is made to obtain the required fuel injection amount by increasing the discharge pressure Ph in the high speed region, the discharge pressure P is also increased in the low speed region.
There is a problem that h is further increased and, as described above, it is necessary to make a compromise setting for adjusting to either rotation region.

Further, FIG. 21 is a graph showing the relationship between the lift amount L of the pressure adjusting valve body 19 and the opening area S of the opening / closing passage 22. In general, as the lift amount L increases, the opening area S increases. S increases linearly. Therefore,
As described with reference to FIG. 19, in order to control the discharge pressure Ph by the set force and the spring constant of the one pressure adjusting spring 21, the engine speed Np-discharge pressure Ph characteristics according to the engine request. There is a problem that there is a limit to making variable.

It is to be noted that a solenoid valve is used for pressure control as in JP-A-2-108849 and JP-A-4-234562, or a sub-feed pump and a bypass valve as in JP-A-6-37559. There is a method of controlling the pressure by using, but both of them have a problem of high cost.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and by making the characteristics variable with respect to the engine speed, it is possible to contribute to improving the engine output. An object of the present invention is to provide a pressure control valve for a fuel pump that can be used.

Another object of the present invention is to provide a pressure control valve for a fuel pump, which can improve the discharge pressure and the fuel consumption in a high engine speed region.

Another object of the present invention is to provide a pressure control valve for a fuel pump which can improve exhaust gas characteristics by controlling the discharge pressure according to the engine speed.

Further, the present invention provides a pressure control valve for a fuel pump, which is capable of variously varying the discharge pressure (injection pressure) of the fuel pump according to the engine speed to adapt it to the required characteristics of the engine. This is an issue.

Another object of the present invention is to provide a pressure control valve for a fuel pump, which can change the fuel injection amount according to the engine speed.

Another object of the present invention is to provide a pressure control valve for a fuel pump in which the degree of freedom in setting characteristics according to the engine speed is expanded.

It is another object of the present invention to provide a pressure control valve for a fuel pump, which can improve the discharge pressure and increase the fuel injection amount in the high engine speed region.

Further, the present invention provides a pressure control valve for a fuel pump, which is compatible with the engine speed, for improving the discharge pressure in the high engine speed region and decreasing the discharge pressure in the low engine speed region. This is an issue.

Another object of the present invention is to provide a pressure control valve for a fuel pump which can obtain the above characteristics without increasing the cost.

[0027]

That is, according to the present invention, a plurality of pressure adjusting springs are provided, a passage area of a low pressure side passage (fuel return passage) is made variable, and a fuel passage area is a pressure adjusting valve. Focusing on making it variable according to the lift of the body, the first invention controls the fuel pressure of the fuel pump that supplies the high-pressure fuel to the injector that injects the high-pressure fuel into the cylinder of the engine. A pressure control valve for a fuel pump, comprising: a pressure adjusting valve body that is lifted from a seat portion by receiving the fuel pressure; and a pressure adjusting spring that urges the pressure adjusting valve body in the seat direction. At the same time, the pressure adjusting spring is a pressure control valve for a fuel pump, which is provided with a plurality of springs.

Two pressure adjusting springs may be provided in series or in parallel.

When the first pressure adjusting spring and the second pressure adjusting spring are provided as the pressure adjusting springs, the pressure adjusting valve body that has received the fuel pressure from the fuel pump is the first one. The first pressure adjusting spring is lifted against the urging force of the pressure adjusting spring so that the second pressure adjusting spring receives the urging force when lifted by a predetermined amount (pre-lift amount). Also, the pressure adjusting valve body can be lifted against the combined biasing force of the second pressure adjusting spring. Therefore, the setting force of the pressure adjusting spring,
The pressure of the fuel pump can be controlled by the spring constant, the pre-lift amount, etc., and the degree of freedom in setting can be expanded.

The second invention is a pressure control valve of a fuel pump for controlling the fuel pressure of a fuel pump for supplying the high-pressure fuel to an injector for injecting the high-pressure fuel into the cylinder of the engine. Thus, a pressure adjusting valve body that allows the high pressure side passage from the injector to communicate with the fuel return passage, and a return passage area varying mechanism that varies the passage area of the fuel return passage are provided. It is the pressure control valve of the fuel pump.

The passage area of the fuel return passage can be made variable by increasing the fuel return amount in the fuel return passage.

As the return passage area variable mechanism,
A check valve may be provided in the fuel return passage (low pressure side passage).

By varying the passage area of the fuel return passage by the return passage area varying mechanism, the back pressure in the fuel return passage is made variable, the lift of the pressure adjusting valve element is controlled, and the discharge pressure of the fuel pump is controlled. Can be controllable.

A third aspect of the present invention is a pressure control valve of a fuel pump for controlling the fuel pressure of a fuel pump for supplying the high pressure fuel to an injector for injecting the high pressure fuel into the cylinder of the engine. Thus, a pressure adjusting valve body that lifts from the seat portion to open the opening / closing passage is provided, and the fuel passage area of the opening / closing passage is changed stepwise according to the lift of the pressure adjusting valve body. It is a pressure control valve of a fuel pump.

The pressure adjusting valve body is opened to the outside as shown in FIG. 18 (the method of opening to the fuel return passage side, that is, the downstream side).
To open the fuel passage (upstream side to the fuel return passage), or by designing the shape of the pressure regulating valve body and the seat portion, the fuel passage area can be increased with the lift. It can be changed.

In the pressure control valve of the fuel pump according to the present invention, its characteristics can be changed with respect to the engine speed with a degree of freedom to improve engine output, improve fuel efficiency, and improve exhaust gas. it can.

For example, in the first invention, from the case of one pressure adjusting spring as shown in FIG. 18, at least two pressure adjusting springs are provided so that the spring constant according to the number of revolutions can be selected. Thus, the discharge pressure can be made variable. Therefore, it is possible to increase the discharge pressure and increase the fuel injection amount in the high rotation region of the engine, and to maintain the constant pressure by suppressing the increase of the discharge pressure in the low rotation region to reduce the drive torque. .

In the second aspect of the invention, the passage area of the low pressure side passage (fuel return passage) of the pressure control valve is made variable by the return passage area varying mechanism using a check valve or the like. When the amount of fuel injected into the cylinder of the engine is large in the region, that is, when the fuel flow rate to the downstream side of the pressure control valve is small, the opening area of the fuel return passage is made small to make the passage area "small", The back pressure in the fuel return passage can be increased. Further, when the fuel flow rate is high in a low engine speed region, the opening area can be increased to make the passage area "large" and the back pressure can be reduced. Thus, the back pressure in this fuel return passage can be controlled with respect to the engine speed.

Therefore, when the amount of fuel injection required by the engine is large, that is, when the fuel flow rate in the fuel return passage is small, the passage area is set to "small" and the back pressure applied to the pressure adjusting valve body is set to "large". It is possible to prevent a relative decrease in the discharge pressure when the required fuel injection amount in the engine is “large”. On the contrary, when the fuel injection amount required by the engine is small, that is, when the fuel flow rate in the fuel return passage is large, the passage area is set to "large",
The back pressure applied to the pressure adjusting valve body is set to "small", and the relative increase in the discharge pressure when the required fuel injection amount in the engine is "small" can be suppressed. Thus, it is possible to reduce the relative difference in the discharge pressure with the increase in the engine speed when the fuel injection amount required by the engine is small and large, and the fuel injection amount in the high engine speed region can be reduced. Can be increased and the rated output can be improved.

In the third aspect of the invention, the fuel passage area of the opening / closing passage formed by the lift of the pressure adjusting valve body from the seat portion is made variable stepwise according to the lift of the pressure adjusting valve body. Therefore, as in the case of the first invention, the discharge pressure of the fuel pump (fuel pressure from the injector or the common rail) is made variable according to the engine speed, and the discharge pressure is increased especially in the high rotation range. Therefore, the fuel injection amount can be increased and the engine output can be improved.

However, in the low rotation speed region of the engine, the discharge pressure can be reduced to reduce the fuel injection amount, so that the discharge pressure is not increased and the drive torque is not increased in the entire rotation speed region. Fuel consumption can be improved.

Further, since the discharge pressure can be finely controlled according to each upturning region, the exhaust gas characteristics can be improved.

Further, since it is easy to reduce the seat diameter of the seat portion of the pressure adjusting valve body, it is possible to increase the valve lift, and it is possible to prevent dust from being caught in the seat portion. It will be easy.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a pressure control valve for a fuel pump according to an embodiment of the present invention will be described with reference to the drawings. However, the same parts as those in FIGS. 18 to 21 are designated by the same reference numerals, and detailed description thereof will be omitted. First, FIGS. 1 to 4
1 is a drawing related to the first invention, FIG. 1 is a cross-sectional view of a main part of a pressure control valve 30 of a fuel pump according to a first embodiment, and in the pressure control valve 30 of the fuel pump,
As a member corresponding to the pressure adjusting spring 21 in the high pressure control valve 10 shown in FIG. 18, a first pressure adjusting spring 31 and a second pressure adjusting spring 3 are used.
2 are provided in series.

The first pressure adjusting spring 31 is the first
In the spring chamber 33 of the pressure adjusting valve body 19
And a spring seat portion 34 of the valve housing 17 are arranged between them, and a first spring setting force adjusting shim 35 is interposed.

The second pressure adjusting spring 32 has a second
In the spring chamber 36 of the pusher rod 37
And a seat housing 20, and a pre-lift adjustment shim 38 is interposed between the pusher rod 37 and the spring seat portion 34. By rotating the seat housing 20 with respect to the valve housing 17, the second pressure adjusting spring 3 is rotated.
The setting force of 2 can be adjusted.

The pusher rod 37 is a pressure adjusting valve body 1.
This is arranged with a gap of 9 and a pre-lift amount Lpre. Further, in the figure, reference numeral 39 indicates a sealing member such as an O-ring.

Pressure control valve 3 of the fuel pump having such a configuration
At 0, the discharge pressure Ph of the high pressure fuel from the high pressure side passage 12 lifts the pressure adjusting valve body 19 against the urging force of the first pressure adjusting spring 31, and as the engine speed increases. , When the pre-lift amount Lpre is lifted, the pressure adjusting valve element 19 and the pusher rod 37 are lifted together against the combined biasing force of the first pressure adjusting spring 31 and the second pressure adjusting spring 32. .

Therefore, as shown in FIG. 2, the passage area between the pressure adjusting valve body 19 and the seat portion (valve seat member 18) varies depending on the cross-sectional shape of the pressure adjusting valve body 19 as it lifts. The discharge pressure Ph characteristic corresponding to the characteristic of the first pressure adjusting spring 31 can be obtained in the low rotation region, and the first pressure adjusting spring 31 and the second pressure can be obtained in the high rotation region. It is possible to obtain the discharge pressure Ph characteristic according to the combined characteristic of the adjusting spring 32. Particularly, by arbitrarily selecting the spring constant of the second pressure adjusting spring 32, the gradient in the high rotation region can be changed.

Further, by arbitrarily selecting the pre-lift amount Lpre, it is possible to set an inflection portion in the graph and set a boundary between the low rotation region and the high rotation region.

Therefore, the engine speed Np (or pump speed) can be set by arbitrarily selecting the set force of the first pressure adjusting spring 31 and the second pressure adjusting spring 32, its spring constant, and the pre-lift amount Lpre. It is possible to set the characteristic of the discharge pressure Ph with respect to the rotational speed.

FIG. 3 is a cross-sectional view of a main part of a pressure control valve 40 of a fuel pump according to the second embodiment. As a member corresponding to the pressure adjusting spring 21, a first pressure adjusting spring 41 and a pressure adjusting valve 41 are provided. Second pressure adjusting spring 4
2 and has a spring seat portion 3 of the valve housing 17 contrary to the case of the pressure control valve 30 of the fuel pump of FIG.
A first spring 41 is provided between the seat 4 and the seat housing 20, and a second pressure adjusting spring 42 is provided between the spring seat portion 34 and the second movable spring seat 43.

That is, the first pressure adjusting spring 41
Is disposed between the seat housing 20 and the first movable spring seat 44, and the seat housing 2
It is possible to adjust the setting force of the first pressure adjusting spring 41 by screwing 0.

The second pressure adjusting spring 42 is
The spring seat portion 34 and the second movable spring seat 4 with the second spring set force adjusting shim 45 interposed therebetween.
3 and the second movable spring seat 43 is seated on the spacer 46.

The pressure adjusting valve body 19 is provided with an intermediate plate 47.
It is connected to the first movable spring seat 44 via the push rod 48.

A pre-lift amount Lpre is set between the intermediate plate 47 and the spacer 46, and depending on the thickness of the spacer 46 or the intermediate plate 47, the pre-lift amount Lpr.
e can be adjusted.

Pressure control valve 4 of the fuel pump having such a configuration
Even at 0, the high pressure fuel pressure from the high pressure side passage 12 resists the urging force of the first pressure adjusting spring 41, the pressure adjusting valve element 19, the intermediate plate 47, the push rod 48, and the first movable spring. When the seat 44 is lifted and lifted by the pre-lift amount Lpre, the first
Pressure adjusting valve body 19 against the combined biasing force of the pressure adjusting spring 41 and the second pressure adjusting spring 42
Will lift.

Therefore, similar to the pressure control valve 30 of the fuel pump of FIG. 1, the characteristics as shown in FIG. 2 can be obtained, and the degree of freedom in design can be expanded.

Since the pre-lift amount Lpre can be adjusted by the thickness of the spacer 46 or the intermediate plate 47, when the pressure control valve 40 of the fuel pump is tightened and attached to the solenoid housing portion 8, the change of the pre-lift amount Lpre is small. can do.

FIG. 4 is a sectional view of a main part of a pressure control valve 50 of a fuel pump according to the third embodiment. As a member corresponding to the pressure adjusting spring 21, a first pressure adjusting spring 51 and a first pressure adjusting spring 51 are provided. 2 pressure adjusting spring 52
Is provided, but the fuel pump pressure control valve 30 (FIG. 1)
Alternatively, unlike the case of the pressure control valve 40 (FIG. 3) of the fuel pump, the first pressure adjusting spring 51 and the second pressure adjusting spring 51
The pressure adjusting springs 52 are provided in parallel.

That is, the first pressure adjusting spring 51
Is provided between the pressure adjusting valve body 19 and the seat housing 20, and the seat housing 20 can be screw-rotated to adjust the setting force of the first pressure adjusting spring 51.

The second pressure adjusting spring 52 is provided between the movable spring seat 54 which is in contact with the spacer 53 and the spring seat portion 34 of the valve housing 17, and the second spring set force adjusting shim 55 is interposed. Let

A pre-lift amount Lpre is set between the pressure adjusting valve body 19 and the spacer 53, and the spacer 53
Since the pre-lift amount Lpre can be adjusted depending on the plate thickness, it is possible to reduce a change in the pre-lift amount Lpre when the pressure control valve 50 of the fuel pump is fastened and attached to the solenoid housing portion 8.

Pressure control valve 5 of the fuel pump having such a configuration
At 0, as with the pressure control valve 30 of the fuel pump of FIG. 1 and the pressure control valve 40 of the fuel pump of FIG. 3, the two first pressure adjusting springs 51 and the second pressure adjusting springs 52 The characteristic as shown in FIG. 2 can be obtained.

The pressure control valve 50 of the fuel pump is the first
Since the pressure adjusting spring 51 and the second pressure adjusting spring 52 are provided in parallel, the vertical dimension can be shortened, and the pressure control valve 30 of the fuel pump and the pressure control valve 40 of the fuel pump have the same width. The dimensions can be reduced.

Next, FIGS. 5 to 11 are drawings related to the second invention, and FIG. 5 is a cross-sectional view of the main part of the pressure control valve 60 of the fuel pump according to the fourth embodiment. In the pressure control valve 60 of the pump, the high pressure control valve 1
In addition to 0, the return passage area variable mechanism 61 is provided on the downstream side.
Is provided.

That is, the return passage area variable mechanism 61
Has a variable area passage 62 in the middle of the low pressure side passage 14 (fuel return passage) in the high pressure control valve 10, and has a check valve 63 provided in the variable area passage 62.
The check valve 63 includes a throttle nozzle 64 that receives fuel pressure from the low pressure side passage 14 and the throttle nozzle 6
4 is a check valve spring 65 that can always urge 4 to the upstream side.
And.

The variable area passage 62 has a conical portion 62A which conically expands from the upstream side to the downstream side thereof and a cylindrical portion 62B which follows the conical portion 62A. The conical portion 62A and the cylindrical portion 62B are further extended from the middle thereof. It communicates with the low pressure side passage 14 on the downstream side.

Throttle nozzle 64 of check valve 63
Has a thinner tip rod portion 64A and a thicker large diameter portion 64B, and the tip rod portion 64A faces the low pressure side passage 14 and the conical portion 62A of the variable area passage 62 located upstream thereof.

Pressure control valve 6 of the fuel pump having such a configuration
At 0, as shown in the graph of FIG.
Area S1 of the area variable passage 62 part in the middle of 4
Changes stepwise according to the lift amount L1 of the throttle nozzle 64 (or the engine speed Np).

In FIG. 6, the solid line shows the case where the fuel injection amount required by the engine is small (the amount of return fuel to the low pressure side passage 14 is large), and the dotted line shows the fuel injection amount required by the engine. Is large (the amount of return fuel to the low pressure side passage 14 is small) (the above-mentioned formula (1), (flow rate through the high pressure control valve 10) = (discharge amount of the high pressure gasoline pump 5) − (Refer to the injection amount of the injector 7).

Further, the opening area up to the point Q at which the lift of the throttle nozzle 64 starts to act effectively can be set as the minimum opening area of the throttle nozzle 64.

Further, as shown in FIG. 7, the lift amount L1 of the throttle nozzle 64 linearly changes from the rotational speed corresponding to the engine rotational speed Np (rotational speed corresponding to the point Q). However, also in FIG. 7 and the following FIGS. 8 and 9, the solid line and the dotted line indicate the case where the fuel injection amount required by the engine is small and the fuel injection amount required by the engine is large, as in FIG. Are shown respectively.

Further, as shown in FIG. 8, the low pressure side passage 14
The gradient of the back pressure Pr in the variable area passage 62 changes from the point Q at which the throttle nozzle 64 starts to lift with respect to the engine speed Np. FIG. 8
In (and FIG. 9 to be described later), the imaginary line is only provided with a throttle mechanism (not shown) for narrowing the passage area of the low pressure side passage 14, and the check valve 63 or the like is not provided as the return passage area variable mechanism 61. The virtual relationship in the case is shown. That is, when the passage area of the variable area passage 62 is not fixed and is fixedly throttled, the engine speed N
The back pressure Pr continues to increase as p increases,
Along with this increase, the discharge pressure Ph also simply increases.

Therefore, as in the pressure control valve 60 of the fuel pump according to the present invention (second invention), by providing the check valve 63 in the return passage area variable mechanism 61, the pressure (or fuel) in the low pressure side passage 14 is increased. The throttle nozzle 64 is lifted in accordance with the flow rate) to make the passage area of the variable area passage 62 variable, so that the back pressure characteristics shown by the solid line and the dotted line in FIG. 8 can be suppressed.

Moreover, when the fuel injection amount required by the engine is large, that is, when the fuel flow rate in the low pressure side passage 14 (fuel return passage) is small, the low pressure side passage 14 is provided.
Or when the passage area of the variable area passage 62 is “small”, the back pressure Pr applied to the pressure adjusting valve body 19 of the high pressure control valve 10 is “large”, and the required fuel injection amount in the engine is “large”. It is possible to prevent a relative decrease in the discharge pressure. Conversely, when the fuel injection amount required by the engine is small, that is, when the fuel flow rate in the low pressure side passage 14 is large, the passage area is set to "large" and the back pressure applied to the pressure adjusting valve body 19 is set to "small". The relative increase in discharge pressure when the required fuel injection amount in the engine is "small" can be suppressed. Thus, it is possible to control the flow rate in the fuel return passage as the engine speed Np increases and reduce the relative difference in the back pressure Pr when the fuel injection amount required by the engine is small or large. it can.

FIG. 9 is a graph showing the relationship of the discharge pressure Ph with respect to the engine speed Np, and the lift of the throttle nozzle 64 effectively acts due to the back pressure Pr characteristic with respect to the engine speed Np as shown in FIG. At the rotation speed Np corresponding to the point Q at which the discharge starts, the discharge pressure Ph has a predetermined gradient.

Therefore, it is possible to reduce the relative difference in the discharge pressure Ph with the increase of the engine speed Np when the amount of fuel injection required by the engine is small and large, and it is possible to reduce the engine speed range. In, it is possible to increase the fuel injection amount and improve the rated output.

As the return passage area variable mechanism 61 and the check valve 62 thereof in the second invention, a modification as shown in FIG. 10 is possible. That is, instead of the throttle nozzle 64, a rod-shaped throttle nozzle 67 is provided, and the area variable passage 68 and the low pressure side passage 14 having a circular cross section corresponding to the area variable passage 62 are provided.
The throttle nozzle 67 can be exposed inside.

FIG. 11 is a graph similar to FIG. 9, showing the relationship between the engine speed Np and the discharge pressure Ph.
Even if the throttle nozzle 67 starts to lift due to the return fuel pressure of the low-pressure side passage 14, the low-pressure side passage 14 is squeezed while facing the inside of the low-pressure side passage 14, as shown in FIG. The discharge pressure Ph rapidly rises and gradually increases with a predetermined gradient when reaching the area variable passage 68 portion. As described with reference to FIG. 9, the engine speed Np when the fuel injection amount required by the engine is small and when the fuel injection amount is large.
It is possible to reduce the relative difference between the discharge pressures Ph due to the rise of the.

In addition, as the structure of the check valve, an on / off valve, a relief valve, or any other desired structure can be adopted. The check valve setting force, spring constant, lift start timing and lift end timing, and further, Desired Ph characteristics can be obtained by arbitrarily designing the shapes of the throttle nozzle and the variable area passage.

The return passage area variable mechanism or its check valve is used as a pressure control valve (high pressure control valve 10).
It is also possible to reduce the control pressure in the pressure control valve by providing it on the upstream side (high pressure side passage 12) and reducing the fuel pressure in the high speed rotation region of the engine.

Next, FIGS. 12 to 17 are drawings relating to the third invention, and FIG. 12 is a cross-sectional view of an essential part of the pressure control valve 70 of the fuel pump according to the fifth embodiment. The pressure control valve 70 of FIG. 18 or the pressure control valve in FIG. 18 or the first and second inventions (the high pressure control valve) is an outward opening valve type, and has a structure of an inside opening valve type. The fuel passage area is made variable according to the lift of the pressure adjusting valve body 71 corresponding to the body 19.

That is, the valve housing 7 corresponding to the valve housing 17 shown in FIG. 1 or FIG.
2, the seat housing 73 corresponding to the seat housing 20, and the valve seat member 74 (seat portion) corresponding to the valve seat member 18 form a spring chamber 75, and the pressure adjusting spring 2 is formed in the spring chamber 75.
1 is accommodated and the pressure adjusting valve body 71 is urged in the seat direction via the spring seat 76.

The bypass passage 77 connecting the spring chamber 75 and the low pressure side passage 14 is connected to the solenoid housing portion 8.
Formed.

An opening / closing passage 78 (phantom line in the figure) corresponding to the opening / closing passage 22 can be formed between the pressure adjusting valve body 71 and the valve seat member 74. The tip rod portion 71A of the pressure adjusting valve body 71 faces the low pressure side hole portion 74A of the valve seat member 74.

Pressure control valve 7 of the fuel pump having such a configuration
At 0, the pressure adjustment valve body 71 is lifted due to the pressure increase from the high pressure side passage 12, and the area of the opening / closing passage 78 is changed.

That is, as shown in FIG. 13, the opening area S2 of the opening / closing passage 78 changes stepwise according to the lift amount L2 of the pressure adjusting valve body 71. Regions I, II, and III of the lift amount L2 in FIG. 13 correspond to regions I, II, and III of the rotation speed Np in FIG. 14, respectively.

As shown in the drawing, the opening area S2 is constant during the so-called throttle state in which the tip rod portion 71A of the pressure adjusting valve body 71 faces the low pressure side hole portion 74A of the valve seat member 74.

Therefore, as shown in FIG. 14, the discharge pressure Ph can be varied stepwise with respect to the engine speed Np.

Further, by forming a multistage taper portion in the opening / closing passage 78 portion or the pressure adjusting valve body 71, it is possible to obtain a multistage Ph characteristic as required as shown in FIG.

Further, the pressure control valve 70 of this fuel pump
Indicates that the pressure adjusting valve body 71 is in the upstream direction (the low pressure side passage 14
From the high pressure side passage 12) to a so-called inward opening valve type, so that the discharge pressure Ph can be controlled by directly controlling the passage area of the opening / closing passage 78 as described above, and for pressure adjustment. Since it is easy to reduce the seat diameter of the valve body 71, the lift amount L of the pressure adjusting valve body 71 is reduced.
2 can be increased, and there is an advantage that dust can be easily prevented from being caught in the sheet portion.

FIG. 16 is a sectional view of a main part of a pressure control valve 80 of a fuel pump according to the sixth embodiment. In the pressure control valve 80 of the fuel pump, the pressure corresponding to the pressure adjusting valve element 19 is used. The valve seat 81 is provided with the adjusting valve body 81.
The effective opening area of the opening / closing passage 22 between the pressure adjusting valve body 81 and the pressure adjusting valve body 81 is made variable with the lift of the pressure adjusting valve body 81.

The valve seat member 18 is attached to the pressure adjusting valve body 81.
Of the upstream side lateral passage 82 that opens toward the inner wall of the pressure regulating valve body 81, the downstream side lateral passage 83 that opens into the middle constricted portion 81A of the pressure adjusting valve body 81, and the upstream side lateral passage 82 and the downstream lateral passage 83 And a vertical passage 84.

A first throttle lift Lt1 is provided between the upper end surface 12A of the high pressure side passage 12 and the lower end portion 81B of the middle constricted portion 81A, and the upper end surface 12A of the high pressure side passage 12 and the upper end surface 82A of the upstream side passage 82 are formed. A second throttle lift Lt2 is defined between and. Further, the passage area of the seat portion between the pressure adjusting valve body 81 and the valve seat member 18 is set to S81, the passage area of the vertical passage 84 is set to S84, and the first throttle lift Lt1 and the second throttle lift Lt2 are set.
The area of the passage between the pressure adjusting valve element 81 and the valve seat member 18, which corresponds to the difference between the two, is S18. However, S1
8 <S84.

Pressure control valve 8 of the fuel pump having such a configuration
At 0, the opening area S3 changes stepwise according to the lift amount L3 of the pressure adjusting valve body 81 as shown in FIG. In the figure, the pressure adjusting valve body 81 is connected to the upstream side passage 8.
2, the change of the passage area S81 when the downstream side passage 83 and the vertical passage 84 are not formed is shown by an imaginary line.

That is, the substantial passage area of the opening / closing passage 22 is the passage area S81 until the pressure adjusting valve body 81 is lifted by the fuel pressure from the high pressure side passage 12 and reaches the first throttle lift Lt1. . Between the first throttle lift Lt1 and the second throttle lift Lt2, the passage area S18 is initially set, and the upper end surface 82A of the upstream side lateral passage 82 reaches the lower end surface 12B of the high pressure side passage 12 and exceeds the upper end surface 12A. Up to the passage area S84. Further, when the lift is made beyond the second throttle lift Lt2, the throttle area is brought about by the passage area S84.

Therefore, similarly to the relationship of FIG. 14 with respect to FIG. 13, the discharge pressure Ph can be changed stepwise according to the engine speed Np.

[0099]

As described above, according to the present invention, a plurality of pressure adjusting springs are used, the passage area of the low pressure side passage (fuel return passage) is made variable, and the fuel passage area is pressure adjusted. By making it variable according to the lift of the valve body, it is possible to change the discharge pressure according to the required characteristics of the engine according to the engine speed, and to change the pressure control valve according to the required characteristics of the engine. The characteristics can be set in many degrees of freedom.

[0100]

[Brief description of the drawings]

FIG. 1 is a drawing related to a first invention and is a cross-sectional view of a main part of a pressure control valve 30 of a fuel pump according to a first embodiment.

FIG. 2 is a discharge pressure Ph with respect to the engine speed Np.
6 is a graph showing the relationship of.

FIG. 3 is a sectional view of an essential part of a pressure control valve 40 of the fuel pump according to the second embodiment.

FIG. 4 is a sectional view of an essential part of a pressure control valve 50 of a fuel pump according to the third embodiment.

FIG. 5 is a drawing related to the second invention and is a cross-sectional view of a main part of a pressure control valve 60 of a fuel pump according to a fourth embodiment.

FIG. 6 is a diagram showing a low pressure passage 14 for a lift amount L1 (or engine speed Np) of a throttle nozzle 64.
6 is a graph showing the relationship of the open area S1 of the area variable passage 62 part in the middle of the process.

FIG. 7 is a graph showing the relationship between the engine speed Np and the lift amount L1 of the throttle nozzle 64.

FIG. 8 is a low pressure side passage 1 with respect to the engine speed Np.
4 is a graph showing the relationship of back pressure Pr in the area 4 to variable area passage 62.

[Fig. 9] Similarly, the discharge pressure Ph with respect to the engine speed Np.
6 is a graph showing the relationship of.

FIG. 10 is a sectional view of relevant parts of a variation of the return passage area variable mechanism 61 or the check valve 62 thereof.

[Fig. 11] Similarly, the discharge pressure P with respect to the engine speed Np.
It is a graph which shows the relationship of h.

FIG. 12 is a drawing relating to the third invention and is a cross-sectional view of the main parts of a pressure control valve 70 of the fuel pump according to the fifth embodiment.

FIG. 13 is a graph showing the relationship between the lift amount L2 of the pressure adjusting valve body 71 and the opening area S2 of the opening / closing passage 78.

[FIG. 14] Similarly, the discharge pressure P with respect to the engine speed Np.
It is a graph which shows the relationship of h.

FIG. 15 is a graph showing the relationship between the lift amount L2 of the pressure adjusting valve body 71 and the opening area S2 of the opening / closing passage 78.

FIG. 16 is a sectional view of a main part of a pressure control valve 80 of a fuel pump according to the sixth embodiment.

FIG. 17 is a graph showing a relationship between the lift amount L3 of the pressure adjusting valve body 81 and the opening area S3.

FIG. 18 is a schematic overall view of a fuel pump 1 for a high-pressure fuel injection device proposed by the present applicant.

FIG. 19 is a discharge pressure P with respect to the engine speed Np.
It is a graph which shows the relationship of h.

FIG. 20 is the same as the discharge pressure P with respect to the engine speed Np.
It is a graph which shows the relationship of h.

FIG. 21 is a graph showing the relationship between the lift amount L of the pressure adjusting valve body 19 and the opening area S of the opening / closing passage 22.

[Explanation of symbols]

1 Fuel pump for high-pressure fuel injection device (Fig. 18) 2 Solenoid valve unit (Fig. 18) 3 Fuel tank 4 Low-pressure feed pump (low-pressure fuel pump) 5 High-pressure gasoline pump (high-pressure fuel pump) such as radial piston pump 6 Common rail 7 Injector 8 Solenoid Housing Part 9 Solenoid Valve 10 High Pressure Control Valve (High Pressure Regulator) 11 High Pressure Side Introduction Port 12 High Pressure Side Passage 12A Upper End Surface of High Pressure Side Passage 12 (FIG. 16, Sixth Embodiment, Third Invention) 12B Lower end surface of high-pressure side passage 12 (FIG. 16, sixth embodiment, third invention) 13 low-pressure side outlet port 14 low-pressure side passage (fuel return passage) 15 high-pressure fuel supply pipe 16 high-pressure fuel control pipe 17 valve Housing 18 Valve seat member (seat part) 19 Pressure Adjusting valve body 20 Seat housing 21 Pressure adjusting spring (regulator spring) 22 Opening / closing passageway 23 Armature 24 Spring seat member 25 Solenoid spring 26 Solenoid 27 Valve seat member 28 Valve body 29 Orifice 30 Fuel pump pressure control valve (Fig. 1) , 1st embodiment, 1st invention) 31 1st pressure adjustment spring 32 2nd pressure adjustment spring 33 1st spring chamber 34 Spring seat part of valve housing 17 35 1st spring set force adjustment Shim 36 Second spring chamber 37 Pusher rod 38 Pre-lift adjustment shim 39 Sealing member such as O-ring 40 Fuel pump pressure control valve (FIG. 3, second embodiment, first invention) 41 First pressure adjustment Spring 4 2 Second pressure adjusting spring 43 Second movable spring seat 44 First movable spring seat 45 Second spring set force adjusting shim 46 Spacer 47 Intermediate plate 48 Push rod 50 Fuel pump pressure control valve (Fig. 4, No. 1) Third Embodiment, First Invention) 51 First Pressure Adjusting Spring 52 Second Pressure Adjusting Spring 53 Spacer 54 Movable Spring Seat 55 Second Spring Set Force Adjusting Shim 60 Fuel Pump Pressure Control Valve (Fig. 5. Fourth embodiment, second invention) 61 Return passage area variable mechanism 62 Area variable passage 62A Conical portion of variable area passage 62B Cylindrical portion of variable area passage 63 Check valve 64 Throttle nozzle 64A Throttle Thinner tip rod part of nozzle 64 64B slot Thicker nozzle 64 with larger diameter 65 Check valve spring 67 Rod-shaped throttle nozzle (Fig. 10, second invention) 68 Circular sectional variable area passage 70 Fuel pump pressure control valve (Fig. 12, 5th embodiment) Form of the third invention) 71 pressure adjusting valve body 71A tip rod portion of the pressure adjusting valve body 71 72 valve housing 73 seat housing 74 valve seat member (seat portion) 74A low pressure side hole portion of the valve seat member 74 75 Spring Chamber 76 Spring Seat 77 Bypass Passage 78 Opening / Closing Passage 80 Fuel Pump Pressure Control Valve (FIG. 16, Sixth Embodiment, Third Invention) 81 Pressure Adjustment Valve Body 81A Pressure Adjustment Valve Body 81 Constricted part 81B Lower end of middle constricted part 81A 82 Upstream lateral passage 82A Upper end surface of upstream lateral passage 82 83 Downstream lateral passage 84 Vertical passage Np Engine speed Ph Discharge pressure from injector 7 (fuel pressure from common rail 6) L Lift amount of pressure adjusting valve body 19 (Fig. 21) S Opening / closing passage for lift amount L of pressure adjusting valve body 19 Opening area of 22 portion (FIG. 21) Lpre Pre-lift amount of the valve body 19 for pressure adjustment (FIG. 1,
3, FIG. 4, first invention) Lift amount of L1 throttle nozzle 64 (FIGS. 6, 7,
Second invention) S1 Variable area passage 62 in the middle of the low pressure side passage 14
Partial aperture area (FIG. 6, second invention) Pr Back pressure in low pressure side passage 14 or area variable passage 62 (FIG. 8, second invention) L2 Throttle lift amount of pressure adjusting valve body 71 (FIG. 1
3, FIG. 15, fifth embodiment, third invention) S2 Opening area of opening / closing passage 78 (FIG. 13, fifth embodiment, third invention) Lt1 Pressure adjusting valve body 81 No. 1 throttle lift (FIG. 16, sixth embodiment, third invention) Lt2 Second throttle lift of pressure adjusting valve body 81 (FIG. 16, sixth embodiment, third invention) L3 Lift amount of valve body 81 for pressure adjustment (FIG. 17, sixth embodiment, third invention) S3 Opening area of opening / closing passage 22 (FIG. 17, sixth embodiment, third invention) S18 A passage area between the pressure adjusting valve body 81 and the valve seat member 18 corresponding to the difference between the first throttle lift Lt1 and the second throttle lift Lt2 (see FIG. 1).
6, sixth embodiment, third invention) S81 A passage area of a seat portion between the pressure adjusting valve body 81 and the valve seat member 18 (FIG. 16, sixth embodiment,
Third invention) S84 Passage area of the vertical passage 84 (FIG. 16, sixth embodiment, third invention)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Aoki 3-13-26, Yasumi-cho, Higashimatsuyama, Saitama Prefecture Zexel Higashimatsuyama Factory

Claims (5)

[Claims] 1. A pressure control valve of a fuel pump for controlling a fuel pressure of a fuel pump for supplying the high-pressure fuel to an injector for injecting the high-pressure fuel into an engine cylinder, the seat part receiving the fuel pressure. And a pressure adjusting spring for urging the pressure adjusting valve body in the seat direction. The pressure adjusting spring is provided with a plurality of pressure adjusting springs. Fuel pump pressure control valve. 2. The pressure control valve for a fuel pump according to claim 1, wherein the pressure adjusting spring is provided in series or in parallel. 3. A pressure control valve of a fuel pump for controlling a fuel pressure of a fuel pump for supplying the high pressure fuel to an injector for injecting the high pressure fuel into a cylinder of an engine, wherein the injector receives the fuel pressure. The fuel pump is provided with: a pressure adjusting valve body capable of communicating the high pressure side passage from the fuel return passage with the fuel return passage; and a return passage area varying mechanism for varying the passage area of the fuel return passage. Pressure control valve. 4. The pressure control valve for a fuel pump according to claim 3, wherein the passage area of the fuel return passage is made variable by increasing the fuel return amount in the fuel return passage. 5. A pressure control valve of a fuel pump for controlling a fuel pressure of a fuel pump for supplying the high-pressure fuel to an injector for injecting the high-pressure fuel into a cylinder of an engine, the seat part receiving the fuel pressure. A pressure adjusting valve element for lifting the valve opening and opening the opening / closing passage is provided, and the fuel passage area of the opening / closing passage is changed stepwise according to the lift of the pressure adjusting valve element. Control valve.