JP4055330B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device capable of injecting fuel in stages.
[0002]
[Prior art]
Conventionally, in order to achieve both low emissions (NOX, HC, black smoke), high output, and low fuel consumption in a diesel engine, it is necessary to make the injection rate variable according to the operating conditions of the engine. In order to realize this requirement, a nozzle having a two-stage valve opening pressure in which two springs are configured so as to bias a needle is known as a conventional technique.
[0003]
However, with this technique, the fuel pressure pumped from the fuel injection pump varies depending on the engine operating condition, so it is difficult to achieve the injection rate required by the engine under all operating conditions.
[0004]
Therefore, for example, a conventional fuel injection valve disclosed in US Pat. No. 5,694,903 includes a control chamber for applying fuel pressure to the needle in the direction of closing the nozzle hole. This controls injection by the magnitude relationship between the force received in the opening direction by the fuel pressure introduced into the nozzle fuel reservoir and the force received in the injection hole closing direction from the fuel pressure in the control chamber. By changing the opening area of the pilot valve stem that controls the fuel pressure in the control chamber, the control chamber pressure is changed, and the needle is lifted stepwise to obtain the required injection rate.
[0005]
[Problems to be solved by the invention]
However, in the configuration of the conventional fuel injection valve disclosed in US Pat. No. 5,694,903, the control chamber and the high-pressure passage to which high-pressure fuel is supplied are always in communication.
[0006]
On the other hand, by changing the opening area of the pilot valve stem that controls the fuel pressure in the control chamber, the control chamber pressure is changed by discharging the high-pressure fuel in the control chamber to the low-pressure passage, and the needle is lifted stepwise. I am letting.
[0007]
That is, while the needle is being lifted, fuel is always discharged from the high-pressure passage to the low-pressure passage through the control chamber, so the supply pump that pumps the high-pressure fuel does a useless work. In particular, the amount of fuel released into the low pressure passage during the second lift operation of the needle is large, and wasteful work increases, causing deterioration of fuel consumption.
[0008]
In view of the above points, the object of the present invention is to suppress wasteful work without releasing high-pressure fuel supplied to the control chamber to the low-pressure passage in order to control the lift in multiple stages, so that the engine can be fully operated. An object of the present invention is to provide a fuel injection device capable of controlling the needle lift stepwise so that the required injection rate can be stably obtained.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, according to the fuel injection device of the first aspect of the present invention, the first pressure chamber and the low pressure passage are communicated with each other in accordance with the switching operation of the control valve, and the valve member is moved to the first lift. A fuel injection device that is operated and then communicates the second pressure chamber and the low pressure passage to cause the valve member to perform a second lift operation, and introduces high pressure fuel from the high pressure passage to the first pressure chamber and the second pressure chamber. Thus, the valve member closes the nozzle hole. When the valve member first lifts from this state, a communication control unit that controls the communication state between the second pressure chamber and the high pressure passage so as to limit the amount of high pressure fuel flowing into the second pressure chamber from the high pressure passage. Provided.
[0010]
The communication control unit controls the communication with the high pressure passage to control the fuel from the high pressure passage to the low pressure passage even if the control valve connects the second pressure chamber for controlling the second lift operation of the valve member and the low pressure passage. Limit release. Therefore, useless work is suppressed and it contributes to fuel consumption improvement.
[0011]
According to the fuel injection device of the second aspect of the present invention, the communication control unit is provided between the valve body and the valve member, and the valve member flows into the second pressure chamber from the high pressure passage by performing the first lift operation. It was configured to limit the amount of high-pressure fuel.
[0012]
In this way, it is possible to provide a fuel injection device that can accommodate the communication control unit in a compact manner between the valve body and the valve member.
[0013]
According to the fuel injection device of the third aspect of the present invention, in accordance with the switching operation of the control valve, the first pressure chamber communicates with the low pressure passage to perform the first lift operation, and then the second pressure chamber A fuel injection device that causes the needle to perform a second lift operation by communicating with the low pressure passage, and the needle closes the injection hole by introducing high pressure fuel from the high pressure passage to the first pressure chamber and the second pressure chamber. . When the needle first lifts from this state, the communication controller that controls the communication between the high pressure passage and the second pressure chamber that controls the second lift operation of the needle is provided with the first lift operation of the housing portion and the needle. And a transmission member that cooperates with the transmission member.
[0014]
The communication control unit controls the communication with the high pressure passage and releases the fuel from the high pressure passage to the low pressure passage even if the second pressure chamber for controlling the second lift operation of the needle and the low pressure passage are connected by the control valve. To control. Therefore, useless work is suppressed and it contributes to fuel consumption improvement.
[0015]
According to the fuel injection device of the fourth aspect of the present invention, before the first lift operation of the needle, the second lift operation is determined by communicating the first annular groove portion, the second annular groove portion, and the third annular groove portion. The needle closes the nozzle hole by communicating the two pressure chambers with the high pressure passage.
[0016]
From this state, the transmission member that cooperates with the first lift operation of the needle completes the first lift operation, so that the end of the third annular groove portion communicates with the first annular groove portion and the second annular groove portion. The communication control unit is configured to control to limit the amount of high-pressure fuel flowing from the second annular groove into the first annular groove.
[0017]
Since the communication control unit can accommodate the communication control unit between the hollow portion in the valve body and the transmission member that cooperates with the first lift operation of the needle, it is possible to provide a compact fuel injection device. It becomes.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
(First embodiment)
The configuration of the fuel injection device according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall cross-sectional view showing a fuel injection device according to a first embodiment of the present invention.
[0020]
As shown in FIG. 1, the structure of the fuel injection device 1 is basically that a first control piston 25 and a second control piston 24 are arranged in a hollow portion 11d in the fuel injection valve housing 11, and each control piston 25, By controlling the fuel pressure in the first pressure chamber 60 and the second pressure chamber 65 facing each of the first and second pressure chambers 60 by the electromagnetic valve 30 disposed above the first pressure chamber 60, the fuel pressure is provided below the second control piston 24. By changing the lift amount of a needle 21 that opens and closes an injection hole 12b, which will be described later, the injection rate shape can be freely set.
[0021]
Here, in the fuel injection device of the present invention, the fuel pressure in the first pressure chamber 60 is changed, and the second control piston 24 together with the first control piston 25 is lifted for the first time, whereby a second control piston 24 and a cavity to be described later are hollow. The communication control unit 10 provided between the high pressure passage 51 and the second pressure chamber 65 for controlling the second lift operation flows into the second pressure chamber from the high pressure passage. The high-pressure fuel amount to be controlled can be controlled. Hereinafter, the overall configuration of the fuel injection device of the present invention will be described in detail with reference to FIG.
[0022]
The fuel injection device 1 is inserted and mounted in an engine head of an engine (not shown), and is configured to directly inject fuel into each cylinder of the engine. The high-pressure fuel discharged from the fuel injection pump is accumulated at a predetermined pressure in a pressure accumulation chamber of a pressure accumulation pipe (not shown) and supplied to the fuel injection device 1. The fuel injection pump adjusts the fuel discharge pressure in accordance with the engine speed, load, or intake fuel pressure, intake air amount, and coolant temperature.
[0023]
The housing 11 and the valve body 12 of the fuel injection device 1 are fastened by a retaining nut 14 with a tip packing 13 interposed therebetween. The valve member 20 includes a needle 21, a rod 23, a second control piston 24, and a first control piston 25 from the nozzle hole 12b side. The rod 23, the second control piston 24, and the first control piston 25 constitute a transmission member.
[0024]
The needle 21 is supported by the valve body 12 so as to reciprocate. The needle 21 is urged by a first spring 15 to a valve seat 12 a formed on the valve body 12 via a rod 23. The second spring 16 is fitted around the rod 23 in the housing 11 so as to be coaxial with the rod 23 and presses the spring seat 17 against the chip packing 13. As shown in FIG. 1, when the spring seat 17 is seated on the tip packing 13, the lower end surface 17a of the spring seat 17 forms a clearance h1 with the shoulder portion 22 of the needle 21, that is, a first lift amount. . When the spring seat 17 is seated on the tip packing 13, the lower end surface 17a of the spring seat 17 protrudes from the lower end surface 13a of the tip packing 13 by h2, that is, the second lift amount. Therefore, the maximum lift amount of the needle 21 is h1 + h2.
[0025]
The electromagnetic valve 30 is fastened to the upper portion of the housing 11 with a nut 31. The electromagnetic valve 30 includes an armature 32, a body 33, a plate 34, a coil 35, a first control valve 40, a second control valve 43, a first spring 42, a second spring 44, and the like. The first control valve 40 and the second control valve 43 are movable members.
[0026]
The second control valve 43 supports the first control valve 40 so as to be reciprocally movable by an inner peripheral wall, and is arranged coaxially. The second control valve 43 can be seated on a valve seat 33 a formed on the body 33 by the biasing force of the second spring 44, and the first control valve 40 can be seated on the plate 34 by the biasing force of the first spring 42. The core 41 located above the first control valve 40 is lifted upward by an exciting suction force generated by energizing the coil 35 and abuts against the end 43a of the second control valve 43 to lift H1 (FIG. 2). ). When the current value supplied to the coil 35 from this position is higher, the exciting suction force acting on the core 41 of the first control valve 40 is increased, the first control valve 40 and the second control valve 43 are both raised, 2 The control valve 43 comes into contact with the locking portion 32b of the armature 32 and is lifted by H2 to stop. Therefore, the first control valve 40 performs the maximum lift of H1 + H2.
[0027]
The first control piston 25 and the second control piston 24 are slidably fitted in the hollow portion 11 d of the housing 11 in the same direction as the axial direction of the needle 21, and the first control piston 25 is moved in the direction opposite to the injection hole. The pressure chamber 60 and the second control piston 24 are arranged so that the second pressure chamber 65 faces the direction opposite to the injection hole, and the fuel pressure in the pressure chambers 60 and 65 is changed to change the first control piston 25 and the first control piston 25, respectively. 2 The control piston 24 was lifted and arranged to cooperate with the needle 21 via the rod 23. In this example, although the 1st control piston 25 and the 2nd control piston 24 were made into a different body, you may comprise integrally.
[0028]
The supply of high-pressure fuel to the first pressure chamber 60 that controls the first lift operation is sequentially introduced into the fuel inlet 50, the high-pressure passage 51, and the inlet throttle 61. In order to change the fuel pressure in the first pressure chamber 60 in the high pressure state to the low pressure state, the first control valve 40 is opened, the outlet throttle 62 formed in the plate 34 is opened, the fuel passage 64, the low pressure The fuel is discharged sequentially to the passage 56 and the fuel outlet 58 and reaches the fuel tank 3. Here, the channel area of the outlet throttle 62 is larger than the channel area of the inlet throttle 61.
[0029]
Supply of high-pressure fuel to the second pressure chamber 65 that controls the second lift operation is introduced into the second pressure chamber 65 through the fuel inlet 50 and the high-pressure passage 51, but the high-pressure passage 51, the second pressure chamber 65, In the meantime, the communication control unit 10 is provided for controlling the communication state between the two so as to limit the amount of high-pressure fuel flowing into the second pressure chamber 65 from the high-pressure passage 51. The communication control unit 10 is provided between the second control piston 24 that cooperates with the first lift operation of the needle 21 and the hollow portion 11d in the housing 11, and the second control piston 24 performs the first lift. Thus, the communication state between the high pressure passage 51 and the second pressure chamber 65 is controlled.
[0030]
In this example, the communication control unit 10 is configured between the second control piston 24 and the hollow portion 11 d in the housing 11. However, for example, a rod that is another transmission member that cooperates with the first lift operation of the needle 21. 23 or the first control piston 25 and the hollow portion 11d in the housing 11 may be configured.
[0031]
The communication control unit 10 described above connects the first annular groove portion 11 a having a diameter larger than the diameter of the cavity portion 11 d provided in the cavity portion 11 d of the housing portion 11, and the first annular groove portion 11 a and the high-pressure passage 51. A second annular groove portion 11b having a diameter larger than the diameter of the hollow portion provided in the hollow portion 11d of the housing portion 11, the second annular groove portion 11b, and the second lift operation of the needle 21 are controlled. The third annular groove having a smaller diameter than the diameter of the second control piston 24 provided in the first communication passage 71 connecting the two pressure chambers 65 and the second control piston 24 cooperating with the first lift operation of the needle 21. 24a.
[0032]
Before the second control piston 24 cooperating with the needle 21 performs the first lift together with the first control piston 25, the high-pressure fuel in the high-pressure passage 51 is the second communication passage 72, the first annular groove portion 11a, the third annular portion. The high pressure fuel is supplied to the second pressure chamber 65 through the groove portion 24 a, the second annular groove portion 11 b, and the first communication passage 71. At this time, the space between the end portion 24b of the third annular groove portion 24a and the end portion 11c of the first annular groove portion 11a is in an open state as shown in FIG.
[0033]
When the second control piston 24 cooperating with the needle 21 performs the first lift h1, the end 24b of the third annular groove 24a moves and lifts more than contacting the end 11c of the first annular groove 11a. Thus, the communication between the first annular groove 11a and the third annular groove 24a is blocked. Therefore, the communication between the second pressure chamber 65 and the high pressure passage 51 is blocked. The first lift amounts h1 and h3 at this time are set so that h1> h3. Here, if h1 <h3 is set, the passage of the first annular groove 11a and the third annular groove 24a is narrowed to restrict the introduction of the high-pressure fuel flowing from the high-pressure passage 51 into the second pressure chamber 65. Can do.
[0034]
In order to change the fuel pressure in the second pressure chamber 65 in the high pressure state to the low pressure state, the second control valve 43 is opened to open the valve seat 33a formed in the body 33, and the fuel passage 68, the fuel passage 64, The low pressure passage 56 and the fuel outlet 58 are sequentially discharged to reach the fuel tank 3. Here, the flow passage area of the outlet throttle 67 provided in the fuel passage 68 is larger than the flow passage area of the inlet throttle 66 provided in the first communication passage 71.
[0035]
Thus, the needle 21 is lifted stepwise by changing the fuel pressure in the first pressure chamber 60 and the second pressure chamber 65 to lift the first control piston 25 and the second control piston 24 stepwise. ing. The needle 21 is seated on the valve seat 12a to close the plurality of nozzle holes 12b. The injection rate is variable by providing the nozzle holes 12b opened by the first lift and the nozzle holes 12b opened by the second lift.
[0036]
Next, the operation of the fuel injection device 1 will be described with reference to FIGS. 1, 2, and 3. FIG. 2 is a partial cross-sectional view showing a first lift according to the first embodiment. FIG. 3 is a partial cross-sectional view showing a second lift according to the first embodiment.
[0037]
First, fuel is discharged from a fuel injection pump (not shown) and delivered to a pressure accumulating pipe (not shown). The high-pressure fuel accumulated at a predetermined fuel pressure in the pressure accumulation chamber of the pressure accumulation pipe is supplied to the fuel injection device 1. Further, a control valve drive current corresponding to the engine operating condition is generated by an engine control unit (ECU) (not shown) and supplied to the coil 35 of the electromagnetic valve 30 shown in FIG. When an exciting suction force is generated in the coil 35 by supplying the drive current, the first control valve 40 is sucked against the biasing force of the first spring 42. Then, the outlet throttle 62 is opened, and the first pressure chamber 60 communicates with the low-pressure side fuel passage 64 via the outlet throttle 62. Since the flow passage area of the outlet throttle 62 is set larger than that of the inlet throttle 61, the amount of outflow fuel is larger than the inflow fuel, and the fuel pressure in the first pressure chamber 60 begins to decrease. The fuel pressure in the first pressure chamber 60 decreases, and the force in the nozzle hole closing direction, which is the resultant force of the set load of the first spring 15 and the force received from the fuel pressure in the first pressure chamber 60 and the second pressure chamber 65, is obtained. When the force becomes smaller than the force that pushes up the needle, the needle 21 starts to open. When the exciting suction force generated by the coil 35 is smaller than the resultant force of the first spring 42 and the second spring 44, the first control valve 40 stops at the position of the first lift amount H1 shown in FIG.
[0038]
When the first control valve 40 is opened and the first lift amount H1 shown in FIG. 2 is reached, the fuel pressure in the first pressure chamber 60 decreases, and the force combined with the initial set load of the first spring 15 decreases. Thus, the needle 21 is pushed up against the first spring 15 by the fuel pressure from the high pressure passage 51, and the first control piston 25 and the second control piston 24 are lifted together via the rod 23, and the needle 21 is in the injection hole 12b. Open the valve. Then, the needle 21 rises to the first lift amount h1. Since the initial set load of the second spring 16 is applied from the first lift amount h1, the needle 21 stops the lift at h1.
[0039]
Here, when the needle 21 lifts the first lift amount h1 together with the second control piston 24, the end 24b of the third annular groove 24a, which is a part of the communication control unit 10, moves, and the first annular groove 11a. The first annular groove portion 11a and the third annular groove portion 24a are disconnected from each other by being lifted beyond the contact with the end portion 11c, and the communication between the second pressure chamber 65 and the high pressure passage 51 is interrupted. At this time, the fuel pressure in the second pressure chamber 65 maintains a high pressure state, and the needle 21 is stopped at the position of the first lift amount h1.
[0040]
Next, when a high current flows through the coil 35 of the electromagnetic valve 30, the excitation attractive force increases, and the second control valve 43 is also valved against the urging force of the first spring 42 and the second spring 44 together with the first control valve 40. The seat 33a is opened and the lift state (H1 + H2) shown in FIG. 3 is reached. When the second control valve 43 opens the valve seat 33a, the high-pressure fuel in the second pressure chamber 65 is discharged. At this time, the connection with the high-pressure passage 51 is blocked by the above-described communication control unit 10 provided on the upstream side of the fuel supply where high-pressure fuel is introduced into the second pressure chamber 65, so that the high-pressure in the second pressure chamber 65 is The fuel pressure drop can be realized with high responsiveness. Therefore, the valve opening response of the needle 21 is improved.
[0041]
Even if the communication control unit 10 is configured to narrow the passage between the second pressure chamber 65 and the high pressure passage 51, the introduction of the high pressure fuel from the high pressure passage 51 to the second pressure chamber 65 is suppressed, and the second pressure is reduced. The pressure drop of the high-pressure fuel in the chamber 65 is promoted, and the valve opening response of the needle 21 is improved. In addition, if the communication control unit 10 is aimed at an appropriate throttle effect, there is a margin in the machining accuracy of the axial position dimensions of the end 24b of the third annular groove 24a and the end 11c of the first annular groove 11a. It becomes easy.
[0042]
In this way, the fuel pressure in the second pressure chamber 65 decreases, and the 21 dollar 21 starts to lift from the first lift amount h1 and rises to the second lift amount h2. The lift of the needle 21 is h1 + h2, and stops at the maximum lift state. When the lift of the needle 21 is in the maximum lift state of h1 + h2, the communication control unit 10 remains disconnected from the second pressure chamber 65 and the high pressure passage 51. Therefore, while the needle 21 is being lifted for the second time, the communication control unit 10 prevents the high pressure fuel from being discharged from the high pressure passage 51 to the low pressure passage 56 via the second pressure chamber 65. The useless work of the supply pump that pumps is suppressed.
[0043]
Further, the above-described communication control unit 10 is configured to narrow the passage between the second pressure chamber 65 and the high pressure passage 51, and can adjust the fuel flow rate between the second pressure chamber 65 and the high pressure passage 51. Therefore, the outlet throttle 67 and the inlet throttle 66 provided at the fuel inlet / outlet of the second pressure chamber 65 can be eliminated. Therefore, it contributes to an improvement in cost and further responsiveness.
[0044]
The shape of the end 24b and the end 11c may not be a surface substantially perpendicular to the axial direction, and may be, for example, a tapered surface or a curved surface.
[0045]
As the fuel pressure in the second pressure chamber 65 decreases, the force for opening the needle 21 further increases, but the shoulder 22 of the needle 21 is locked to the lower end surface 13 a of the tip packing 13. Therefore, the needle 21 does not lift any more. The tip packing 13 receives the load in the nozzle hole opening direction.
[0046]
When the predetermined drive pulse time has passed, the supply of drive current to the coil 35 is stopped, and the first control valve 40 and the second control valve 43 are closed. When the first control valve 40 closes the outlet throttle 62, the first pressure chamber 60 is in a high pressure state by the high pressure fuel from the inlet throttle 61, and the first control piston 25 and the second control cooperate with the needle 21. The piston 24 moves in the valve closing direction. With the movement of the second control piston 24, the end portion 24b of the third annular groove portion 24a, which is a part of the communication control portion 10, moves and passes through the end portion 11c of the first annular groove portion 11a. 11a communicates with the third annular groove 24a. Therefore, the second pressure chamber 65 and the high pressure passage 51 are communicated, and high pressure fuel is introduced into the second pressure chamber 65.
[0047]
On the other hand, when the second control valve 43 is seated on the valve seat 33a, the second pressure chamber 65 is in a high pressure state, and a force in the valve closing direction of the needle 21 is added, so that the needle 21 is completely closed. The valve state is reached, and the nozzle hole 12b is reliably closed to the state shown in FIG.
[0048]
(Second Embodiment)
The second embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a fuel injection device according to a second embodiment of the present invention. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0049]
In the first embodiment and the second embodiment, the first control piston and the second control piston, and the fuel pressure in the first pressure chamber and the second pressure chamber respectively facing the control piston are controlled by the solenoid valve 30. Although the lift amount of the needle 21 is changed and the injection rate shape can be freely set, the arrangement of the first pressure chamber and the second pressure chamber facing the first control piston and the second control piston is different. Also in the second embodiment, the second control piston that cooperates with the first lift operation of the needle 21 as in the first embodiment performs the first lift, thereby controlling the high pressure passage 51 and the second lift operation. The communication control unit 10 is configured to control the communication state with the two pressure chambers so as to limit the amount of high-pressure fuel flowing from the high-pressure passage 51 into the second pressure chamber.
[0050]
Hereinafter, the configuration of the fuel injection device according to the second embodiment will be described focusing on the periphery of the communication control unit 10. The configuration of the electromagnetic valve 30 in FIG. 4 is schematically shown. The valve portion 30a of the electromagnetic valve 30 shows a state where no drive current is supplied to the coil 35, the valve portion 30b shows a state where only the first control valve is lifted, and the valve portion 30c includes the first control valve and The state which the 2nd control valve is lifting is shown.
[0051]
The first control piston 27 is located on the side opposite to the injection hole of the second control piston 24. In a state where the needle 21 is seated on the valve seat 12a, the first control piston 27 is not in contact with the second control piston 24. A first pressure chamber 60 is formed between the second control piston 24 and the first control piston 27, and a second pressure chamber 65 is formed on the opposite side of the first control piston 27 from the first pressure chamber 60. Yes.
[0052]
Here, the supply of high-pressure fuel to the second pressure chamber 65 that controls the second lift operation is introduced into the second pressure chamber 65 through the fuel inlet 50 and the high-pressure passage 51. A communication control unit 10 that controls communication between the chamber 65 and the chamber 65 is provided. The communication control unit 10 is provided between the second control piston 24 that cooperates with the first lift operation of the needle 21 and the hollow portion 11d in the housing 11, and the second control piston 24 performs the first lift. Thus, the communication state between the high pressure passage 51 and the second pressure chamber 65 is controlled to limit the amount of high pressure fuel flowing into the second pressure chamber 65 from the high pressure passage 51.
[0053]
Before the second control piston 24 cooperating with the needle 21 performs the first lift, the high-pressure fuel in the high-pressure passage 51 flows through the second communication passage 72, the first annular groove portion 11a, the third annular groove portion 24a, and the second annular groove. The high pressure fuel is supplied to the second pressure chamber 65 by being introduced into the groove portion 11 b and the first communication passage 71 in order. At this time, the space between the end portion 24b of the third annular groove portion 24a and the end portion 11c of the first annular groove portion 11a is in an open state as shown in FIG.
[0054]
In the process in which the valve portion 30b is selected and the second control piston 24 cooperating with the needle 21 performs the first lift h1 and contacts the first control piston 27, the end portion 24b of the third annular groove portion 24a moves. The first annular groove portion 11a and the third annular groove portion 24a are disconnected from each other by being lifted beyond the end 11c of the first annular groove portion 11a. Therefore, the communication between the second pressure chamber 65 and the high pressure passage 51 is blocked. The first lift amounts h1 and h3 at this time are set so that h1> h3.
[0055]
Next, the valve portion 30c is selected, and the first control piston 27 and the second control piston 24 both perform a second lift.
[0056]
When a predetermined drive pulse time has passed, supply of drive current to the coil 35 is stopped, the valve portion 30a is selected, the first pressure chamber 60 is in a high fuel pressure state, and the second control piston 24 is closed. Move in the direction. At this time, the communication control unit 10 causes the high pressure passage 51 and the second pressure chamber 65 to communicate with each other, the second pressure chamber 65 is also in a high fuel pressure state, the needle 21 is completely closed, the injection hole 12b is closed, and the injection is performed. Stop.
[0057]
In the above embodiment, a two-stage lift is realized. However, for example, even if the number of control chambers that apply fuel pressure to the valve member in the injection hole closing direction is three or more, the communication control unit 10 controls the second and subsequent stages. The communication between the chamber and the high-pressure passage can be blocked.
[0058]
In the above description of the operation, the control example in which the switching to the second lift operation of the needle is performed in the process of one injection is shown. However, as a control example performed in the process of one injection other than this example, For example, the second lift operation is performed in the high speed range, and the valve is closed only by the first lift operation in the low speed range.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view showing a fuel injection device according to a first embodiment of the present invention.
FIG. 2 is a partial sectional view showing a first lift according to the first embodiment.
FIG. 3 is a partial sectional view showing a second lift according to the first embodiment.
FIG. 4 is a cross-sectional view showing a fuel injection device according to a second embodiment of the present invention.
[Explanation of symbols]
12b nozzle hole
21 Needle (Valve member)
12a Valve seat
12 Valve body
60 First pressure chamber
65 Second pressure chamber
51 High pressure passage
56 Low pressure passage
30 Control valve
1 Fuel injector
10 Communication control unit
24, 25, transmission member (valve member)
11 Housing
11d cavity
11b First annular groove
11a Second annular groove
24a Third annular groove
71 First communication passage
72 Second communication passage
24b End of third annular groove

Claims (4)

A valve member for opening and closing the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the valve member is seated on the valve seat to close the nozzle hole, and the valve member is separated from the valve seat; A valve body that opens the nozzle hole;
A first pressure chamber and a second pressure chamber for applying fuel pressure to the valve member in the nozzle hole closing direction;
A high pressure passage for introducing high pressure fuel into the first pressure chamber and the second pressure chamber;
A control valve that switches a communication state with a low-pressure passage that discharges the high-pressure fuel from the first pressure chamber and the second pressure chamber;
In response to the switching operation of the control valve, the first pressure chamber and the low pressure passage are communicated to cause the valve member to perform a first lift operation, and then the second pressure chamber and the low pressure passage are communicated. In the fuel injection device for causing the valve member to perform a second lift operation,
Communication control for controlling the communication state between the second pressure chamber and the high pressure passage so as to limit the amount of high pressure fuel flowing from the high pressure passage into the second pressure chamber during the first lift operation of the valve member. A fuel injection device comprising a portion. The communication control unit is provided between the valve body and the valve member, and limits the amount of high-pressure fuel flowing into the second pressure chamber from the high-pressure passage when the valve member performs a first lift operation. The fuel injection device according to claim 1, wherein the fuel injection device is configured as follows. A needle that opens and closes the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the needle is closed on the valve seat to close the nozzle hole, and the needle is separated from the valve seat to cause the injection. A valve body that opens a hole;
A plurality of transmission members cooperating with the needle;
A housing portion having a hollow portion in which the transmission member is slidably disposed;
The transmission member slidably disposed inside the cavity,
A first pressure chamber and a second pressure chamber for applying fuel pressure to the transmission member in the nozzle hole closing direction;
A high pressure passage for introducing high pressure fuel into the first pressure chamber and the second pressure chamber;
A control valve that switches a communication state with a low-pressure passage that discharges the high-pressure fuel from the first pressure chamber and the second pressure chamber;
In response to the switching operation of the control valve, the first pressure chamber and the low-pressure passage are communicated to cause the needle to perform a first lift operation, and then the second pressure chamber and the low-pressure passage are communicated. In the fuel injection device for causing the needle to perform the second lift operation,
A communication control unit that controls the communication state between the second pressure chamber and the high pressure passage so as to limit the amount of high pressure fuel flowing from the high pressure passage into the second pressure chamber during the first lift operation of the needle. And the communication control part is provided between the transmission member cooperating with the first lift operation of the needle and the housing part. The communication control portion includes a first annular groove portion having a diameter larger than the diameter of the hollow portion provided in the housing portion,
A first communication passage connecting the first annular groove and the second pressure chamber;
A second annular groove portion having a diameter larger than the diameter of the hollow portion provided in the housing portion;
A second communication passage connecting the second annular groove and the high-pressure passage;
A third annular groove provided on the transmission member that cooperates with the first lift operation of the needle, and having a diameter smaller than the diameter of the cavity;
Before the first lift operation of the needle, the first annular groove, the second annular groove, and the third annular groove are communicated to communicate the second pressure chamber and the high-pressure passage.
When the transmission member cooperating with the first lift operation of the needle completes the first lift operation, the end of the third annular groove portion communicates with the first annular groove portion and the second annular groove portion. The fuel injection device according to claim 3, wherein the fuel injection device is configured to control the amount of high-pressure fuel flowing into the first annular groove from the second annular groove.

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