JPH08189445A - Solenoid valve unit for fuel injection device - Google Patents

Abstract

PURPOSE: To provide a solenoid valve for a fuel injector, by which generation of vapor is suppressed even in a hot restart and certainty of action can be improved, by stabilizing fuel force feeding in a start, of an engine. CONSTITUTION: Considering that a valve opening pressure of a check valve 44, which is arranged in the downstream of a solenoid valve 43, is set to be lower than the valve opening pressure of a low-pressure pressure control valve in a high pressure gasoline pump, the check valve 44 arranged between a low pressure side passage 16 and a fuel tank and the low-pressure pressure control valve arranged between a high pressure pump and the fuel tank are arranged. A valve opening pressure of the low-pressure pressure control valve is set to be higher than the valve opening pressure of the check valve 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve unit for a fuel injection system, and more particularly to a fuel injection system capable of appropriately controlling the fuel pressure in a cylinder gasoline injection system at the time of starting and during normal operation. The present invention relates to a solenoid valve unit.

[0002]

2. Description of the Related Art In a conventional in-cylinder gasoline injection system, when the engine is restarted when it is still hot after the engine is stopped, that is, at the time of so-called hot restart, the temperature in the engine room remains high, so fuel (for example,
There is a problem that bubbles (vapor) are easily generated in the pipe of gasoline). Therefore, a mechanism for maintaining the stability of the fuel pressure and eliminating the vapor at the time of the hot restart is required.

In particular, when the fuel is pressure-fed to the injector by using a high-pressure pump such as a high-pressure gasoline pump driven by the rotation of the engine, the high-pressure pump discharges a small amount of fuel when the engine speed is low. There is a problem that it is difficult to remove the vapor during the hot restart.

In Japanese Patent Laid-Open No. 5-321782, a pressure adjusting valve is provided between a high pressure pump and a low pressure pump, and fuel from an overflow control valve in the high pressure pump is circulated to the pressure adjusting valve to recirculate the fuel to the high pressure pump. Disclosed is a fuel injection device that makes the pressure on the suction side of the fuel injection device constant.

Further, as a mechanical pressure flow control valve,
It is disclosed in Japanese Utility Model Publication No. 60-56872. In such a mechanical pressure control valve, when the pressure of fuel pumped from the pump exceeds the urging force of the valve urging spring, fuel is injected from the injector via the common rail (high pressure accumulator). Is able to.

As described above, in order to solve various problems such as difficulty in air bleeding at the time of hot restart, insufficient fuel injection amount at the time of starting or at extremely low speed, and pressure instability of high-pressure fuel, A solenoid valve unit for a fuel injection device as shown in FIGS. 11 to 14 has been proposed (see Japanese Patent Application No. 6-139729 by the present applicant).

FIG. 11 is a schematic view of the fuel injection device 1, FIG.
2 is a cross-sectional view of a solenoid valve unit 2 using a single solenoid valve. The fuel injection device 1 includes a fuel tank 3, a low pressure feed pump (low pressure pump) 4,
It has a high-pressure gasoline pump (high-pressure pump) 5, a common rail 6, an injector 7, and a solenoid valve unit 2.

The low-pressure feed pump 4 electrically drives the engine (not shown) irrespective of the number of revolutions of the engine, and therefore its discharge amount is constant regardless of the number of revolutions of the engine. The high-pressure gasoline pump 5 is driven by the rotation of the engine, and supplies the common rail 6 and therefore the injector 7 with an amount of fuel according to the engine speed.
It can be pumped at high pressure.

The solenoid valve unit 2 has a high pressure control valve 8 and a single solenoid valve 9, and has a high pressure side introduction port 10 of the high pressure control valve 8 and a low pressure side derivation port 11 of the high pressure control valve 8. High pressure control valve 8 between
And the solenoid valve 9 are connected in parallel,
A return port 12 from the high pressure gasoline pump 5 is connected to a solenoid valve 9. A control circuit 13 for the solenoid valve 9 is provided.

As shown in FIG. 12, in the solenoid valve unit 2, the high pressure control valve 8 and the solenoid valve 9 are arranged in a unit housing 14 thereof, and a high pressure side introduction port 10, a low pressure side discharge port 11 and a return are provided. The port 12 is opened.

The high pressure control valve 8 is the high pressure side introduction port 1
High pressure side passage 15 and low pressure side outlet port 1 communicating with 0
1. The pressure adjusting valve body (valve body) 17 is seated on the valve seat member 18, and the pressure adjusting spring 19 moves the pressure adjusting valve body 17 so as to intersect the low pressure side passage 16 communicating with 1. By energizing in the valve closing direction, the high pressure side passage 15 and the low pressure side passage 16 are shut off.

When the pressure from the high pressure side introduction port 10 becomes excessively high, the pressure adjusting valve body 17 lifts from the valve seat member 18 against the urging force of the pressure adjusting spring 19 to adjust the pressure. An opening / closing passage 20 (phantom line in the drawing) that connects the high-pressure side passage 15 and the low-pressure side passage 16 can be formed between the valve body 17 and the valve seat member 18. In addition,
The structure of the high pressure control valve 8 may be a spool valve type.

The solenoid valve 9 is connected to the high pressure side passage 15 described above.
And the low pressure side passage 16 and the return port side passage 21 are provided so as to straddle the armature 22, the spring seat member 23, and the solenoid spring 24.
And the spring seat member 25 and the valve spring 2
6, a solenoid 27, a first valve body 28,
It has a connecting rod 29, a second valve body 30, and a valve seat member 31.

First valve body 28, connecting rod 29
And the second valve body 30 has this armature 2
The first valve body 28 is seated on the first seat surface 31A of the valve seat member 31,
The second valve body 30 is the second of the valve seat member 31.
The sheet can be seated on the seat surface 31B.

The valve seat member 31 is formed with a communication passage 31C capable of communicating the high pressure side passage 15 and the low pressure side passage 16, and the return port side passage 21 and the low pressure side passage 16.

In the solenoid valve 9 having such a configuration, its operation will be described with reference to the chart of the operating state of each element of FIG. 13 and the graph of the fuel pressure and the engine speed of FIG. 14, and the chart of FIG. like,
When starting the engine, set the solenoid valve 9 to "OF
By setting "F", the first valve body 28 lifts from the first seat surface 31A to "open" between the high pressure side passage 15 and the low pressure side passage 16 (in the chart of FIG. 13, The high-pressure side passage 15 is shown as “open”), and the second valve body 30 seats on the second seat surface 31B to “close” between the return port side passage 21 and the low-pressure side passage 16. (In the diagram of FIG. 13, the return port side passage 21 is shown as “closed”).

Therefore, since the space between the high pressure side passage 15 and the low pressure side passage 16 is "open", the high pressure side passage 15
Does not rise to high pressure, and the common rail 6 in FIG.
And the pressure of the injector 7 becomes low pressure, and the low pressure fuel using the low pressure feed pump 4 instead of the high pressure gasoline pump 5 can be started. (Refer to the column of “used pump” in FIG. 13) Further, since the low pressure side passage 16 and the return port side passage 21 are not in communication with each other, the inside of the fuel pipe from the low pressure feed pump 4 having a constant discharge amount has a low pressure. A large amount of fuel flows, the inside of the fuel pipe is filled with the fuel, and the generation of vapor can be suppressed. Even at this start-up, the high pressure gasoline pump 5 is cooled and lubricated without any problem by the large flow rate of fuel from the low pressure feed pump 4.

Returning to the diagram of FIG. 13, when the engine is in normal high pressure operation after a complete explosion, the solenoid valve 9 is turned on so that the first valve body 28 is seated on the first seat surface 31A. Then, the high pressure side passage 15 and the low pressure side passage 1
6 is closed and the second valve body 30 is in the second position.
When the space between the return port side passage 21 and the low pressure side passage 16 is "opened" by lifting from the seat surface 31B of the above, the high pressure side passage is closed because the high pressure side passage 15 and the low pressure side passage 16 are "closed". 15 rises to high pressure, the pressures of the common rail 6 and the injector 7 become high, and high-pressure injection using the high-pressure gasoline pump 5 is performed. Further, when the solenoid valve 9 is turned “ON”, the second valve body 30 lifts from the second seat surface 31B, and the low pressure side passage 16
Since the return port side passage 21 communicates with the return port side passage 21, cooling and lubrication of the high-pressure gasoline pump 5 with fuel are smoothly performed as usual.

The fuel pressure to the common rail 6 or the injector 7 and the engine speed change with time are shown in FIG.
As shown in FIG. 4, by setting an accessory position (not shown) of the key to “ON”, the low-pressure feed pump 4 starts to operate and its fuel pressure rises, and further, the ignition position (not shown) of the key. )) To "O
By setting to "N", the engine starts cranking. Until the ignition position is turned "ON", the high pressure side passage 15 and the low pressure side passage 16 are "opened".
In addition, the connection between the return port side passage 21 and the low pressure side passage 16 is “closed”, and when the ignition position is “ON”, the low pressure start by the low pressure feed pump 4 is performed as described above.

Turn the solenoid valve 9 from "OFF" to "O".
If it is “N”, as described above, the space between the high pressure side passage 15 and the low pressure side passage 16 is “closed” and the return port side passage 2
It is possible to “open” between 1 and the low pressure side passage 16,
After that, even if the solenoid valve 9 is turned "OFF", the state between the high pressure side passage 15 and the low pressure side passage 16 is "closed" and the state between the return port side passage 21 and the low pressure side passage 16 is "open". (See the control signal to the solenoid 27 shown in FIG. 14), the control signal to the solenoid 27 can be simplified, and the energization time of the solenoid 27 can be shortened.

After this low pressure start, the space between the high pressure side passage 15 and the low pressure side passage 16 is "closed" and the return port side passage 2
By "opening" between 1 and the low pressure side passage 16,
As the engine speed increases, the fuel pressure increases, and normal high pressure operation is performed by high pressure fuel injection.

When the key is turned "OFF", the high pressure side passage 15 and the low pressure side passage 16 are "open" and the return port side passage 21 and the low pressure side passage 16 are "closed". .

According to the solenoid valve unit 2, the single solenoid valve 9 (the single solenoid 2
Since the high pressure side passage 15 and the return port side passage 21 can be opened / closed by 7), it is possible to contribute to cost reduction.

As described above, at the time when the engine is completely detonated and the normal high pressure operation is performed, the fuel pressure from the high pressure side introduction port 10 is sufficiently high even if the solenoid valve 9 is turned off. (Because of the so-called high-pressure biasing type structure in which the high pressure of fuel acts in the seat direction of the first valve body 28 of the solenoid valve 9), the first valve body 28 resists the biasing force of the solenoid spring 24. First seat surface 31A of the valve seat member 31
The seat state to the high pressure side passage 15 and the low pressure side passage 16 is maintained in a "closed" state, so that high pressure fuel can be supplied by the high pressure gasoline pump 5 and high pressure fuel can be supplied. The holding property can be improved.

Therefore, the control signal to the solenoid 27 of the solenoid valve 9 can be simplified (see FIG. 1).
(See the control signal to the solenoid 27 shown in FIG. 4). Further, the solenoid 27 of the solenoid valve 9 may have a small generated force.

However, as shown in FIG. 13, the solenoid valve 9 is turned off after the engine is stopped.
By setting the high pressure side passage 15 and the low pressure side passage 16 from "closed" to "open", the return port side passage 2
It becomes possible to change from "open" to "close" between 1 and the low-pressure side passage 16. That is, once the pressure becomes high, the fuel pressure cannot be made low until the engine is stopped. Therefore, when the transmission (not shown) is switched, the pressure between the high pressure side passage 15 and the low pressure side passage 16 is " When the engine speed is reduced while the "closed" state is maintained and the space between the return port side passage 21 and the low pressure side passage 16 is kept "open" and the high pressure gasoline pump 5 cannot be switched to the low pressure feed pump 4. Since the discharge amount of the high-pressure gasoline pump 5 also decreases, engine stall may occur. Therefore, after the engine is started, the low-pressure feed pump 4 ensures a predetermined flow rate of the low-pressure fuel even if the engine is extremely low-speed, and the high-pressure and the low-pressure are switched according to the operating condition of the engine during normal operation as necessary. Is desirable.

Further, the solenoid valve unit 2
In this case, since the high pressure control valve 8 and the solenoid valve 9 for switching between high pressure and low pressure are separately required, it is difficult not only to reduce the cost of parts but also to downsize the whole, reduce the number of assembling steps, and improve the reliability. There is a problem.

[0028]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and various circumstances, and it is possible to perform stable fuel pressure feeding at the time of starting the engine, so that the present invention is particularly effective at the time of hot restart. It is an object of the present invention to provide a solenoid valve unit for a fuel injection device that can suppress the generation of vapor even at any time and improve the reliability of operation.

Another object of the present invention is to provide a solenoid valve unit for a fuel injection device, which is capable of sending fuel at a low pressure at the time of starting and switching to a high pressure at the time of normal operation.

Further, according to the present invention, the fuel can be sent at a low pressure at the time of starting, and the pressure can be switched to a high pressure at the time of normal operation by constructing the pressure switching valve from a single solenoid valve (electromagnetic valve), thereby enabling cost reduction. An object is to provide a solenoid valve unit for a fuel injection device.

Further, according to the present invention, a magnet valve (on / off valve) is used to secure a predetermined flow rate of low-pressure fuel by a low-pressure pump even after the engine is started and the engine is at an extremely low rotation speed. Also, it is possible to switch between high pressure and low pressure as needed according to the operating condition of the engine, and at the time of starting or extremely low speed, fuel injection by low pressure fuel supply pressure (common rail pressure) by the low pressure pump. It is an object of the present invention to provide a solenoid valve unit for a fuel injection device that enables the above.

Further, according to the present invention, the control signal of the solenoid valve can be simplified by causing the high pressure fuel to face the valve body of the solenoid valve in the direction opposite to the seat direction (high pressure facing type). An object of the present invention is to provide a solenoid valve unit for an injector.

Further, the present invention provides a solenoid valve unit for a fuel injection device, which can realize simplification and cost reduction of the solenoid valve unit by integrating a high pressure control valve and a solenoid valve for switching between high pressure and low pressure. The challenge is to provide.

[0034]

[Means for Solving the Problems] That is, the first invention is
A high pressure opposed type is adopted instead of the high pressure bias type described based on FIG. 12, a check valve is provided downstream of the solenoid valve, and the opening pressure of this check valve is set to the low pressure control valve of the high pressure gasoline pump. Focusing on making the pressure lower than the valve pressure, the fuel injection device includes a low-pressure pump that supplies low-pressure fuel from a fuel tank, and a high-pressure pump that supplies low-pressure fuel from the low-pressure pump as high-pressure fuel to an injector of an engine. A solenoid valve unit for a vehicle, wherein a unit housing having a high pressure side introduction port from the injector and a low pressure side introduction port to the fuel tank is provided, and a high pressure side passage communicating with the high pressure side introduction port, and A low-pressure side passage communicating with the low-pressure side outlet port is formed in this unit housing to It is possible to communicate with the high-pressure side introduction port and the low-pressure side outlet port through a high-pressure pressure control valve that communicates or blocks the high-pressure side passage and the low-pressure side passage according to the pressure of the introduction port, and the high-pressure pressure control valve. A solenoid valve that opens and closes between the high-pressure side passage and the low-pressure side passage, a check valve arranged between the low-pressure side passage and the fuel tank, and between the high-pressure pump and the fuel tank. The low pressure control valve to be arranged is provided, and the opening pressure of the low pressure control valve is set to be larger than the opening pressure of the check valve, and at the time of starting the engine, the high pressure side passage and the low pressure side passage are And controlling the solenoid valve so that the high pressure side passage and the low pressure side passage are shut off during normal operation of the engine. A fuel injection system for a solenoid valve unit according to symptoms.

The second aspect of the present invention focuses on forming an orifice in the high pressure side passage to arbitrarily set the pressure in the pipe, and a low pressure pump for supplying low pressure fuel from a fuel tank, and this low pressure pump. A high-pressure pump that supplies low-pressure fuel from the engine to the injector of the engine as high-pressure fuel,
A solenoid valve unit for a fuel injection device having: a high pressure side introduction port from the injector;
A unit housing having an opening for the low pressure side outlet port to the fuel tank is provided, and a high pressure side passage communicating with the high pressure side inlet port and a low pressure side passage communicating with the low pressure side outlet port are formed in this unit housing. A high pressure control valve that connects or disconnects the high pressure side passage and the low pressure side passage according to the pressure of the high pressure side introduction port, and the high pressure side introduction port and the low pressure side discharge port via the high pressure pressure control valve. A solenoid valve that is communicable and that opens and closes between the high-pressure side passage and the low-pressure side passage, and a low-pressure pressure control valve that is arranged between the high-pressure pump and the fuel tank are provided. When the orifice is formed in the passage and the solenoid valve is opened, the opening pressure of this low pressure control valve is made larger than the pressure in the high pressure side passage. The diameter of the orifice is set so that the high pressure side passage and the low pressure side passage are communicated with each other when the engine is started, and the high pressure side passage and the high pressure side passage are connected during normal operation of the engine. A solenoid valve unit for a fuel injection device, wherein the solenoid valve is controllable so as to shut off the low-pressure passage.

The third aspect of the present invention focuses on integrating the high pressure control valve and the solenoid valve for switching between high pressure and low pressure, and includes a low pressure pump for supplying low pressure fuel from a fuel tank, and a low pressure pump from this low pressure pump. A high-pressure pump for supplying low-pressure fuel as high-pressure fuel to an injector of an engine, and a solenoid valve unit for a fuel injection device, wherein a high-pressure side introduction port from the injector and a low-pressure side discharge port to the fuel tank are provided. A unit housing having an opening is provided, and a high-pressure side passage communicating with the high-pressure side introduction port and a low-pressure side passage communicating with the low-pressure side discharge port are formed in this unit housing, and the pressure of the high-pressure side introduction port is adjusted depending on the pressure. A high pressure control valve that connects or disconnects the high pressure side passage and the low pressure side passage,
A solenoid valve for opening and closing between the high-pressure side passage and the low-pressure side passage is provided, and the solenoid valve and the high-pressure pressure control valve are integrated by making their respective valve bodies common. It is a characteristic solenoid valve unit for a fuel injection device.

The high pressure control valve, the solenoid valve, and the check valve or the orifice can be formed in a single unit housing.

A damper portion can be formed on the low pressure side or the high pressure side of the high pressure control valve.

The valve body of the solenoid valve or the high-pressure control valve may be a flat valve body.

[0040]

In the fuel injector solenoid valve unit according to the present invention, since the high pressure side passage and the low pressure side passage are communicated with each other when the engine is started, the pressure on the high pressure pump side of the high pressure control valve rises. Therefore, the low-pressure fuel from the low-pressure pump is directly supplied to the common rail or the injector without the need for high-pressure pumping of the fuel. Further, since the high pressure side passage and the low pressure side passage are cut off during the normal operation of the engine, the pressure of the high pressure pump rises, and the normal high pressure fuel can be pumped.

That is, by utilizing the characteristics of the low-pressure pump, which has a low discharge pressure but is capable of obtaining a sufficient discharge flow rate at the time of starting, the high-pressure pump is invalidated at the time of engine starting, or the fuel supply circuit is arranged so as not to perform fuel compression here. By switching between the two, the fuel is supplied using the low-pressure pump instead of the high-pressure pump, so it is possible to supply a sufficient amount of fuel to the injector, especially at the time of starting, and to prevent Occurrence can be suppressed. After the engine is completely detonated after the engine is started, by switching the solenoid valve, it is possible to perform normal fuel supply, that is, supply of high-pressure fuel from the high-pressure pump.

According to the first aspect of the invention, the opening pressure of the low pressure control valve of the high pressure pump is set higher than the opening pressure of the check valve of the solenoid valve unit. At times, the above-mentioned action can be realized, and even during normal operation after the complete explosion, the low pressure control valve is kept in the "closed" state by turning the solenoid "ON / OFF" according to the operating state of the engine. It is possible to "open and close" the check valve and immediately "open and close" the solenoid valve, enabling the low pressure pump to supply the required amount of fuel as needed at low speed without stopping the engine. A stable fuel supply can be realized.

Further, according to the second invention, the solenoid valve is “opened” (ON) by arbitrarily setting the diameter of the orifice formed in the high pressure side passage instead of the check valve as in the first invention. Since the pressure in the high pressure side passage can be set lower than the valve opening pressure of the low pressure control valve at this time, the same operation as that of the first invention can be expected without using the check valve.

Furthermore, according to the third aspect of the invention, since the high pressure control valve and the solenoid valve are integrated, it is possible to switch between high pressure and low pressure by operating a single valve body, thereby reducing cost and downsizing. It is possible to improve reliability.

[0045]

Embodiment Next, an embodiment of the first invention (first embodiment)
Fig. 1 shows a solenoid valve unit for a fuel injection device
It will be described with reference to FIG. However, the same parts as those in FIGS. 11 to 14 are designated by the same reference numerals, and the detailed description thereof will be omitted. FIG. 1 is a schematic diagram of a solenoid valve unit 41 for a fuel injection device 40. The fuel injection device 40 includes a fuel tank 3, a low pressure feed pump (low pressure pump) 4, and a high pressure gasoline pump 5 ( High pressure pump) and low pressure control valve 4 of high pressure gasoline pump 5
2, the common rail 6, and the injector 7
And a solenoid valve unit 41. The common rail 6 is connected to the injector 7 via the first bank rail 6A and the second bank rail 6B having a smaller capacity.

The solenoid valve unit 41 has a single solenoid valve 43, the high pressure control valve 8 and a check valve 44, and the solenoid valve 43 is provided with an orifice 45. A return connection point 47 is provided from the check valve 44 through the low pressure side outlet port 46.

A high pressure control valve 8 and a solenoid valve 43 are provided in parallel between the high pressure side inlet port 10 and the low pressure side outlet port 46, and a check valve 4 is provided.
4 are provided in series.

FIG. 2 is a sectional view of the solenoid valve unit 41. The high pressure control valve 8 has substantially the same structure as that shown in FIG. 12, and a check valve 44 is arranged downstream of the low pressure side passage 16. I am doing it.

The solenoid valve 43 is provided in the high pressure side passage 15
And the low pressure side passage 16 are provided so as to straddle the armature 48 and the spring seat member 49.
, A solenoid spring 50, a solenoid 51,
It has a valve seat member 52 and a valve body 53.

The valve body 53 is formed integrally with the tip of the armature 48.
3 seats on the seat surface 52A of the valve seat member 52, and the valve seat member 52 is formed with a communication passage 52B capable of communicating the high pressure side passage 15 and the low pressure side passage 16 via the orifice 45.

The opening pressure of the low pressure control valve 42 is set higher than the opening pressure of the check valve 44.

In the solenoid valve unit 41 having such a configuration, a chart showing the operating state of each element in FIG.
The operation will be described with reference to the graphs of the fuel pressure and the engine speed shown in FIG. 4, and as shown in the chart of FIG. 3, when the engine is started, the solenoid valve 43 is turned “ON” so that the valve The body 53 lifts from the seat surface 52A of the valve seat member 52 to “open” the space between the high pressure side passage 15 and the low pressure side passage 16 (in the diagram of FIG. 3, the high pressure side passage 15 is shown as “open”). Since the opening pressure of the low pressure control valve 42 is higher than the opening pressure of the check valve 44, the low pressure control valve 42 is "closed".

Therefore, since the space between the high pressure side passage 15 and the low pressure side passage 16 is "open", the high pressure side passage 15
Does not rise to a high pressure, the pressures of the common rail 6 and the injector 7 in FIG. 1 become a low pressure, and the low-pressure fuel can be started using the low-pressure feed pump 4 instead of the high-pressure gasoline pump 5. ("Used pump" in Figure 3
In addition, a large amount of low-pressure fuel flows in the fuel pipe from the low-pressure feed pump 4 having a constant discharge amount, and the fuel pipe is filled with the fuel, so that the generation of vapor can be suppressed. Even at this start-up, the high pressure gasoline pump 5 is cooled and lubricated without any problem by the large flow rate of fuel from the low pressure feed pump 4.

Returning to the diagram of FIG. 3, the solenoid valve 43 is turned “OFF” during normal high pressure operation after the engine is completely exploded.
As a result, the valve body 53 has the seat surface 52A.
When the seat between the high-pressure side passage 15 and the low-pressure side passage 16 is “closed”, the high-pressure side passage 15 rises to a high pressure, the pressures of the common rail 6 and the injector 7 become high, and the high-pressure gasoline pump 5 is used. The high-pressure injection was performed. Further, when the solenoid valve 43 is turned “OFF”, the high-pressure side passage 15 rises to high pressure, the pressures of the common rail 6 and the injector 7 become high pressure, and the low-pressure control valve 42 is also opened as appropriate to turn off the high-pressure gasoline pump 5. Cooling and lubrication with fuel will proceed smoothly as usual.

The fuel pressure to the common rail 6 or the injector 7 and the engine speed change with time are shown in FIG.
As shown in FIG. 4, by setting the accessory position (not shown) of the key to “ON”, the low-pressure feed pump 4 starts to operate and its fuel pressure rises, and further, the ignition position (not shown) of the key. ) To "O
By setting to "N", the engine starts cranking. Until the ignition position is turned "ON", the high pressure side passage 15 and the low pressure side passage 16 are "opened".
In addition, the low pressure control valve 42 is closed and the low pressure start is performed by the low pressure feed pump 4 as described above at the time when the ignition position is “ON”.

Turn the solenoid valve 43 from "ON" to "O".
FF ”, as described above, the space between the high pressure side passage 15 and the low pressure side passage 16 is“ closed ”, and the low pressure pressure control valve 42.
Can be "open".

When the key is turned "OFF", the high pressure side passage 15 and the low pressure side passage 16 are "closed" and the low pressure control valve 42 is "closed".

Since the check valve 44 is arranged downstream of the solenoid valve 43 and the high pressure control valve 8, the low pressure of a predetermined pressure can be maintained even after the engine is stopped.

In the present embodiment, the valve body 53 is of a high pressure facing type so as to face the high pressure and seat on the seat surface 52A of the valve seat member 52, and the valve body 53 is biased in the direction of closing the high pressure side passage 15. Therefore, as described above, the solenoid valve 43 is set to “ON” at the time of starting, and the solenoid valve 43 is set to “OF” at the time of normal operation after the complete explosion.
It is sufficient to perform two-step control by simply setting "F".
Compared to the three-stage control in which the solenoid valve unit 2 according to FIGS. 1 to 14 is "OFF" at the start, "ON" after the complete explosion, and "OFF" again during the normal operation, the valve is stopped until the engine is stopped. It does not mean that the body 53 does not operate, and the "O" of the solenoid valve 43 is
The valve body 53 is immediately activated by "FF" and its control is easy.

Moreover, as shown in FIG. 3, even during the normal operation after the complete explosion, the valve body 53 is immediately ready to be operated by changing the solenoid valve 43 from "OFF" to "ON" during the normal low pressure operation. Becomes That is, when the solenoid valve 43 is turned "ON", the valve body 53 is lifted from the seat surface 52A so that the space between the high pressure side passage 15 and the low pressure side passage 16 is "opened", and the check is performed. Since the valve opening pressure of the valve 44 is lower than the valve opening pressure of the low pressure control valve 42, the low pressure control valve 42 remains closed and a required amount of fuel is supplied from the low pressure feed pump 4 instead of the high pressure gasoline pump 5 to the common rail. Or can be supplied to the injector 7.

Next, in the present invention, the high pressure side passage 15
"Open (ON)" of the solenoid valve 43 by setting the diameter of the orifice 45 communicating with the solenoid valve to a predetermined value.
Sometimes, the set valve opening pressure of the low pressure control valve 42 is the high pressure side passage 15
The check valve 44 does not need to be provided as long as it is possible to realize a relationship in which the pressure is larger than the pressure.

That is, FIG. 5 is a schematic view of a solenoid valve unit 56 for a fuel injection device 55 according to an embodiment (second embodiment) of the second invention, and FIG. 6 is a sectional view of the solenoid valve unit 56. Yes, the fuel injector 55
Is a fuel tank 3, a low-pressure feed pump (low-pressure pump) 4, a high-pressure gasoline pump 5 (high-pressure pump), a low-pressure control valve 42 of the high-pressure gasoline pump 5, a common rail 6, an injector 7, and a solenoid valve unit. 56 and.

The solenoid valve unit 56 is shown in FIG.
2 is different from the solenoid valve unit 41 shown in FIG. 2 in that the check valve 44 is omitted, and the set valve opening pressure of the low pressure control valve 42 when the solenoid valve 43 is “open (ON)” is the high pressure side passage 15. The diameter of the orifice is selected so as to be larger than the pressure.

By using the solenoid valve unit 56 having such a configuration, the same operation as that of the solenoid valve unit 41 described above, which is shown in FIG. 3, can be achieved. Therefore, the description thereof will be omitted. However, when the diameter of the orifice 45 is increased, it is necessary to strengthen the solenoid spring 50 in the solenoid valve 43, that is, to strengthen (enlarge) the solenoid valve 43. Therefore, only by setting the diameter of the orifice 45, the low pressure control valve is required. The set valve opening pressure of 42 is the high pressure side passage 15
There is a limit to making the pressure larger than the pressure of 1. In such a case, it is necessary to provide the check valve 44 and configure the solenoid valve unit 41 of FIGS. 1 and 2.

The third invention is characterized in that the solenoid valve 43 portion and the high pressure control valve 8 portion in the first invention are integrated. A solenoid valve unit 60 according to an embodiment (third embodiment) of the third invention will be described with reference to FIG. FIG.
3 is a cross-sectional view of the solenoid valve unit 60, wherein the solenoid valve unit 60 is the valve housing 1;
4 has the check valve 44 and a single solenoid valve 61.

The solenoid valve 61 has a structure in which the high pressure control valve 8 and the solenoid valve 43 in the solenoid valve unit 41 according to the first embodiment are integrated, and includes an armature portion 62A, a valve body portion 62B, and It has a needle valve 62 integrally formed with a damper portion 62C on the high pressure side. The needle valve 62 integrates and shares the pressure adjusting valve body 17, which is the valve body of the high-pressure control valve 8, the armature 48 and the valve body 53 of the solenoid valve 43.

The armature portion 62A is acted upon by the solenoid 51 and the solenoid spring 50, and the valve body portion 62B is acted upon by the pressure adjusting spring 19 to connect and disconnect the high pressure side passage 15 and the low pressure side passage 16 to establish a damper. The portion 62C is the sliding hole A1 of the valve seat member 18.
By sliding inside 8, the damper effect is exhibited.
The solenoid spring 50 may not be provided if the biasing force of the pressure adjusting spring 19 is appropriately set.

In the solenoid valve unit 60 having such a structure, the armature portion 62A is pulled upward by turning the solenoid 51 "ON", so that the valve body portion 62B is lifted from the valve seat member 18 and the high pressure side passage is opened. 15 and the low pressure side passage 16 are connected. Therefore, similar to the solenoid valve unit 41, the fuel of the required flow rate is supplied from the low-pressure feed pump 4 instead of from the high-pressure gasoline pump 5 at the time of starting the common rail 6.
Or can be supplied to the injector 7.

When the solenoid 51 is turned "OFF", the valve body 62B seats on the valve seat member 18, shuts off the passage between the high pressure side passage 15 and the low pressure side passage 16, and opens the pressure adjusting spring 19. Since the valve body portion 62B is opened / closed according to the pressure and the fuel pressure, the same function as that of the high pressure control valve 8 can be exerted.

Further, in the operation of the needle valve 62, even if the fuel pressure from the high pressure side passage 15 is temporarily changed or abnormally changed, the needle valve 62 slides in the sliding hole 18A with a predetermined oil tightness. Since the damper portion 62C exerts a damper effect, the needle valve 62 is prevented from overshooting or undershooting, and stability as the high pressure control valve 8 can be provided.

In the second embodiment, the damper portion 6
2C is provided on the high-pressure side passage 15 side, that is, on the high-pressure side, but it may be provided on the low-pressure side passage 16 side, that is, on the low-pressure side. FIG. 8 is a sectional view of a solenoid valve unit 70 according to another embodiment (third embodiment) in which a damper portion is provided on the low pressure side. The solenoid valve unit 70 has a solenoid valve 71.

The solenoid valve 71 is the valve seat member 1
8 to the valve seat member 72, the needle valve 62
Is provided, and a pressure adjusting spring 74 corresponding to the pressure adjusting spring 19 and the solenoid spring 50 is provided.

The needle valve 73 has an armature damper portion 73 in which an armature portion and a damper portion are integrated.
A and the valve body 73B are integrally formed,
The valve body portion 73B is seated on the valve seat member 72. The armature damper portion 73A slides vertically in the sliding cylinder portion 75.

In the solenoid valve 71 having such a structure, the armature damper portion 73A is lifted upward in the figure by turning the solenoid 51 "ON", so that the valve body portion 73B is lifted from the valve seat member 72 and the high pressure side. The passage 15 and the low pressure side passage 16 communicate with each other. Therefore, similar to the solenoid valve unit 41, the fuel of the required flow rate is supplied from the low-pressure feed pump 4 instead of from the high-pressure gasoline pump 5 at the time of starting the common rail 6.
Or can be supplied to the injector 7.

When the solenoid 51 is turned "OFF", the valve body portion 73B seats on the valve seat member 72, shuts off the passage between the high pressure side passage 15 and the low pressure side passage 16, and opens the pressure adjusting spring 74. Since the valve body portion 73B is opened / closed according to the pressure and the fuel pressure, it is possible to exhibit the same function as that of the high pressure control valve 8.

The check valve 44 can be omitted as in the second aspect of the invention by arbitrarily setting the diameter of the orifice 45 that opens and closes the valve body portion 73B.

Further, in the operation of the needle valve 73 as described above, a predetermined oil-tightness is maintained in the sliding cylindrical portion 75 to slide against the primary fluctuation or abnormal fluctuation of the fuel pressure from the high pressure side passage 15. The armature damper portion 73A that performs the above-described function exhibits a damper effect, whereby the needle valve 73 is prevented from overshooting or undershooting, and the high pressure control valve 8 can be provided with stability.

Therefore, also in the solenoid valve 71 according to the third embodiment, the same effect as the solenoid valve 61 (FIG. 7) in the second embodiment is exerted, and the action of the high pressure control valve 8 and the solenoid are performed. The action of the valve 43 can be obtained.

If it is desired to further increase the damper effect, a flat plate type valve body 76 may be used instead of the rod type such as the valve body 62 or the valve body 73 as shown in FIG. it can. The valve body 76 includes an armature damper portion 76A in which a flat plate-shaped armature portion and a circumferential flange-shaped damper portion are integrated, and a conical valve body portion 7.
6B is integrally formed, and the valve body portion 73B is seated on the valve seat portion 77 in which the high pressure side passage 15 is opened. The armature damper portion 76A slides vertically on the inner wall surface of the solenoid chamber 78.

With this structure, the cross-sectional area of the armature damper portion 76A as the armature portion becomes large, and the damping force can be increased.

Further, the solenoid valve 43 portion and the high pressure control valve 8 portion in the first aspect of the invention, such as the solenoid valve 61 and the solenoid valve 71, are integrally formed, so that the valve as shown in FIG. Since the seat portion is one place like the seat member 18 (FIG. 7) or the valve seat member 72 (FIG. 8), the control pressure of the solenoid valve 61 and the solenoid valve 71 does not decrease even at a low flow rate (in the drawing, (Solid line), a constant pressure can be controlled.

[0082]

As described above, according to the present invention, it is possible to supply low-pressure fuel to the injector by the low-pressure pump with no load on the high-pressure pump at the time of starting, so that it is possible to prevent the occurrence of vapor at the time of hot restart, During high-pressure operation, high-pressure fuel can be supplied from a high-pressure pump as before.
It is possible to realize stable engine driving.

Further, according to the first aspect of the invention, since the opening pressure of the low pressure control valve of the high pressure pump is set to be higher than the opening pressure of the check valve of the solenoid valve unit, even during normal operation after the complete explosion of the engine. By controlling the solenoid valve, it becomes possible to control the supplied fuel pressure to a high pressure or a low pressure as required.

According to the second invention, the same operation as the first invention can be achieved by setting the diameter of the orifice of the high pressure side passage instead of the check valve.

According to the third aspect of the invention, since the high pressure control valve and the solenoid valve are integrated, the cost can be reduced, the overall size can be reduced, and the reliability can be improved.

[0086]

[Brief description of drawings]

FIG. 1 is a schematic diagram of a solenoid valve unit 41 for a fuel injection device 40 according to an embodiment (first embodiment) of the first invention.

FIG. 2 is a sectional view of a solenoid valve unit 41 of the same.

FIG. 3 is a diagram showing an operating state of each element in the solenoid valve unit 41.

FIG. 4 is a graph of fuel pressure to the injector 7 and engine speed.

FIG. 5 is a solenoid valve unit 56 for a fuel injection device 55 according to an embodiment (second embodiment) of the second invention.
FIG.

FIG. 6 is a sectional view of a solenoid valve unit 56 of the same.

FIG. 7 is a sectional view of a solenoid valve unit 60 provided with a damper portion on the high pressure side according to an embodiment (second embodiment) of the third invention.

FIG. 8 is a sectional view of a solenoid valve unit 70 provided with a damper portion on the low pressure side according to another embodiment (third embodiment) of the third invention.

FIG. 9 is a main-portion cross-sectional view showing an example in which a flat plate type valve body 76 is adopted in the third invention.

FIG. 10 is a graph showing the relationship between the flow rate and the control pressure applied to the solenoid valve in the third invention.

FIG. 11 has been proposed in order to solve various problems such as difficulty in air bleeding at the time of hot restart, insufficient fuel injection amount at the time of starting or at extremely low speed, and pressure instability of high-pressure fuel. FIG. 3 is a schematic diagram of the fuel injection device 1.

FIG. 12 is a sectional view of a solenoid valve unit 2 using the same solenoid valve.

FIG. 13 is a chart of the operating status of each element in the solenoid valve 9.

FIG. 14 is a graph of fuel pressure applied to the injector 7 and engine speed.

[Explanation of symbols]

 1 Fuel Injector 2 Solenoid Valve Unit of Fuel Injector 1 3 Fuel Tank 4 Low Pressure Feed Pump (Low Pressure Pump) 5 High Pressure Gasoline Pump (High Pressure Pump) 6 Common Rail 6A First Bank Rail 6B Second Bank Rail 7 Injector 8 High Pressure Pressure control valve 9 Single solenoid valve 10 High pressure side introduction port 11 Low pressure side discharge port 12 Return port 13 Solenoid valve control circuit 14 Unit housing 15 High pressure side passage 16 Low pressure side passage 17 Pressure adjustment valve body (valve body) 18 Valve seat member 18A Sliding hole of valve seat member 19 Pressure adjusting spring 20 Opening / closing passage 21 Return port side passage 22 Armature 23 Spring seat member 24 Solenoid spring 25 Spring seat member 26 Valves Ring 27 Solenoid 28 First valve body 29 Connecting rod 30 Second valve body 31 Valve seat member 31A First seat surface of valve seat member 31B Second seat surface of valve seat member 31C Valve seat member 31 Communication passage 40 Fuel injection device 41 Solenoid valve unit of fuel injection device 40 42 Low pressure control valve 43 Single solenoid valve 44 Check valve 45 Orifice 46 Low pressure side outlet port 47 Return connection point 48 Armature 49 Spring seat member 50 Solenoid spring 51 Solenoid 52 Valve seat member 52A Seat surface of valve seat member 52 52B Communication passage of valve seat member 53 Valve body 55 Fuel injection device 56 Solenoid valve of fuel injection device 55 Knit 60 Solenoid valve unit 61 Single solenoid valve 62 Needle valve 62A Needle valve 62 armature part 62B Needle valve 62 valve body part 62C Needle valve 62 damper part 70 Solenoid valve unit 71 Solenoid valve 72 Valve seat member 73 Needle valve 73A Needle valve 73 armature damper part 73B Needle valve 73 valve body part 74 Pressure adjusting spring 75 Sliding cylinder part 76 Valve body 76A Valve body 76 armature damper part 76B Valve body 76 valve body part 77 Valve seat Part 78 Solenoid chamber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuro Hozumi 3-13-26, Yasuyukicho, Higashimatsuyama-shi, Saitama Prefecture XXEL Higashi-Matsuyama Plant (72) Inventor Takeo Kushida 3--13, Hakumatsucho, Higashimatsuyama, Saitama No.26 Stock Company Zexel Higashi Matsuyama Factory

Claims (7)

[Claims] 1. A solenoid valve unit for a fuel injection device, comprising: a low pressure pump for supplying low pressure fuel from a fuel tank; and a high pressure pump for supplying low pressure fuel from the low pressure pump as high pressure fuel to an injector of an engine. A unit housing having a high-pressure side introduction port from the injector and a low-pressure side discharge port to the fuel tank is provided, and a high-pressure side passage communicating with the high-pressure side introduction port and a low-pressure side discharge port are provided. A low-pressure side passage is formed in this unit housing, and a high-pressure control valve that connects or disconnects the high-pressure side passage and the low-pressure side passage according to the pressure of the high-pressure side introduction port; The high-pressure side inlet port and the low-pressure side outlet port can communicate with each other, and the high-pressure side passage and the front A solenoid valve that opens and closes between the low pressure side passage, a check valve arranged between the low pressure side passage and the fuel tank, a low pressure pressure control valve arranged between the high pressure pump and the fuel tank, The opening pressure of the low pressure control valve is set to be higher than the opening pressure of the check valve, and when the engine is started, the high pressure side passage and the low pressure side passage are communicated with each other, and A solenoid valve unit for a fuel injection device, wherein the solenoid valve is controllable so as to block the high-pressure side passage and the low-pressure side passage during normal operation. 2. A solenoid valve unit for a fuel injection device, comprising: a low pressure pump for supplying low pressure fuel from a fuel tank, and a high pressure pump for supplying low pressure fuel from the low pressure pump as high pressure fuel to an injector of an engine. A unit housing having a high-pressure side introduction port from the injector and a low-pressure side discharge port to the fuel tank is provided, and a high-pressure side passage communicating with the high-pressure side introduction port and a low-pressure side discharge port are provided. A low-pressure side passage is formed in this unit housing, and a high-pressure control valve that connects or disconnects the high-pressure side passage and the low-pressure side passage according to the pressure of the high-pressure side introduction port; The high-pressure side inlet port and the low-pressure side outlet port can communicate with each other, and the high-pressure side passage and the front A solenoid valve that opens and closes a low-pressure side passage and a low-pressure pressure control valve that is arranged between the high-pressure pump and the fuel tank are provided, an orifice is formed in the high-pressure side passage, and the solenoid valve is The diameter of the orifice is set so that the opening pressure of the low pressure control valve can be set to be larger than the pressure in the high pressure side passage when the valve is opened. And the low pressure side passage are communicated with each other, and the solenoid valve is controllable so as to disconnect the high pressure side passage and the low pressure side passage during normal operation of the engine. Solenoid valve unit for. 3. A solenoid valve unit for a fuel injection device, comprising: a low-pressure pump for supplying low-pressure fuel from a fuel tank, and a high-pressure pump for supplying low-pressure fuel from the low-pressure pump as high-pressure fuel to an injector of an engine. A unit housing having a high-pressure side introduction port from the injector and a low-pressure side discharge port to the fuel tank is provided, and a high-pressure side passage communicating with the high-pressure side introduction port and a low-pressure side discharge port are provided. A low-pressure side passage is formed in this unit housing, and a high-pressure control valve that connects or disconnects the high-pressure side passage and the low-pressure side passage according to the pressure of the high-pressure side introduction port; the high-pressure side passage and the low-pressure side passage And a solenoid valve for opening and closing between the solenoid valve and the high pressure control. The valve is a solenoid valve unit for a fuel injection device, which is integrated by making each valve body common. 4. The high pressure control valve, the solenoid valve, and the check valve or the orifice are formed in a single unit housing, as claimed in any one of claims 1 to 3. A solenoid valve unit for a fuel injection device described in 1. 5. The solenoid valve unit for a fuel injection device according to claim 3, wherein a damper portion is formed on the low pressure side of the high pressure control valve. 6. The solenoid valve unit for a fuel injection device according to claim 3, wherein a damper portion is formed on the high pressure side of the high pressure control valve. 7. The solenoid valve unit for a fuel injection device according to claim 3, wherein the solenoid valve or the valve body of the high-pressure control valve is a flat valve body.