JP4407590B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device for an internal combustion engine, particularly a diesel engine.

  A common rail system is known as a fuel injection device for an internal combustion engine. This common rail system includes a pressure accumulator (common rail) that stores fuel in a predetermined pressure state, and injects high pressure fuel supplied from the pressure accumulator into a cylinder of an internal combustion engine from an injector. It has excellent performance such as being able to be controlled independently. In recent years, there has been a demand for higher performance from such a common rail system in terms of exhaust gas purification and fuel consumption reduction, and it is necessary to increase the injection pressure. A known technique that can easily realize this has been proposed (see Patent Document 1).

  The fuel injection device described in Patent Literature 1 includes a “mechanism for controlling the opening / closing operation of the nozzle by hydraulic pressure”, which is an advantage of the common rail system, and a pressure increasing mechanism for increasing the pressure in the accumulator. By providing this pressure increasing mechanism, not only can injection be performed at a higher pressure, but both pressure increasing and injection can be controlled. As a result, it is possible to change the injection pressure in one injection cycle, and it is possible to realize a fine injection at a low pressure and a main injection at an ultra-high pressure, and an injection rate pattern can be optimized. Can be optimized.

However, in the above known technique (Patent Document 1), it is necessary to control two operations, that is, a pressure increasing operation and an injection operation independently, so that at least two actuators are required. There is a problem that the configuration of the system becomes complicated and the cost increases accordingly.
On the other hand, another system has been proposed that can more easily realize the same function as the above-described known technique (Patent Document 1) (see Patent Document 2).

FIG. 13 is a hydraulic circuit diagram of the fuel injection device described in Patent Document 2.
This fuel injection device has a control valve 100 driven by one actuator, and this control valve 100 is connected to a pressure intensifier 110 and a nozzle 120 by fuel passages 130 and 140, respectively. To the pressure accumulator 160. The control valve 100 is provided with a hydraulic port 101 connected to the fuel passages 130 and 140 and a low-pressure port 102 connected to the low-pressure side drain passage 170, and the valve body 103 is connected between the hydraulic port 101 and the low-pressure port 102. The valve is driven between a valve closing position for blocking the gap (the state shown in FIG. 13) and a valve opening position for communicating between the hydraulic pressure port 101 and the low pressure port 102.

  When the valve body 103 is driven to the valve closing position, the fuel pressure of the pressure accumulator 160 is supplied to the control chamber 111 of the pressure intensifier 110 and the back pressure chamber 121 of the nozzle 120. At this time, in the pressure booster 110, the hydraulic pressure on both the upper and lower sides is balanced with respect to the built-in hydraulic piston 112, so that the fuel supplied from the pressure accumulator 160 through the fuel passage 180 to the high pressure chamber 113 is not boosted. Absent. On the other hand, the nozzle 120 receives the fuel pressure in the back pressure chamber 121, and a built-in needle (not shown) maintains a valve-closed state, so that injection is not performed.

Next, when the valve body 103 is driven to the valve open position, the hydraulic port 101 and the low pressure port 102 of the control valve 100 communicate with each other, so that the fuel pressure in the control chamber 111 and the back pressure chamber 121 passes through the control valve 100. Open to the low pressure side. Thereby, in the pressure intensifier 110, the pressure balance between the upper and lower sides of the hydraulic piston 112 is lost, and the hydraulic piston 112 moves downward in the figure, whereby the fuel in the high pressure chamber 113 is increased and supplied to the nozzle 120. Further, in the nozzle 120, the fuel pressure in the back pressure chamber 121 is lowered and the needle is lifted, so that the ultra-high pressure fuel supplied from the pressure intensifier 110 is injected.
Japanese Patent No. 2885076 JP 2003-106235 A

  However, in the fuel injection device described in Patent Document 2, the control chamber 111 of the pressure intensifier 110 and the back pressure chamber 121 of the nozzle 120 are always connected to the pressure accumulator 160. That is, regardless of whether the control valve 100 is open or closed, the control chamber 111 and the back pressure chamber 121 are always in communication with the pressure accumulator 160. For this reason, throttles 190, 200, 210 are provided in the fuel passages 130, 140, 150, respectively. However, even if these three throttles 190-210 are used, the throttles 190-210 affect each other. It is difficult to optimally control the operation of the intensifier 110 and the operation of the nozzle 120.

In particular, although the characteristics of the pressure feeding stroke and the return stroke of the pressure intensifier 110 can be set respectively, when the control valve 100 is opened, the fuel pressure of the pressure accumulator 160 is released to the low pressure side via the control valve 100. Since the fuel flows down from the pressure accumulator 160 and the restriction is restricted in order to reduce energy loss, optimization is further difficult.
The present invention has been made based on the above circumstances, and its purpose is to control the pressure increasing operation of the pressure intensifier and the nozzle injection operation with high accuracy by a control valve driven by one two-position actuator. In addition, a fuel for an internal combustion engine that can prevent a decrease in the degree of freedom of control due to a single actuator, and can prevent fuel from flowing down from the pressure accumulator when the control chamber of the pressure intensifier is opened to the low pressure side. It is in providing an injection device.

(Invention of Claim 1)
The present invention includes a hydraulic pressure supply mode that is driven by a single two-position actuator and supplies fuel pressure in an accumulator or a high pressure chamber to a control chamber of a pressure intensifier and a back pressure chamber of a nozzle, A control valve that switches between a hydraulic release mode that opens the valve to the low pressure side, and a first port connected to the control chamber, and is operated by introducing fuel pressure according to the operation mode of the control valve. It is equipped with a hydraulic valve configured as a three-way valve that switches the port communication destination to either the high pressure side or the low pressure side, and the control valve controls the fuel pressure in the back pressure chamber directly to control the nozzle injection operation A fuel injection device for an internal combustion engine that controls the pressure increase operation of the pressure intensifier by controlling the fuel pressure in the control chamber indirectly through at least a hydraulic valve, Intensifier As delay in pressure operated, characterized in that it to have a delay in operation timing of the hydraulic valve.

According to the above configuration, the fuel pressure in the back pressure chamber provided in the nozzle is directly controlled by the control valve, whereas the fuel pressure in the control chamber provided in the pressure intensifier is indirectly controlled via at least the hydraulic valve. Since the control valve is switched from the hydraulic pressure supply mode to the hydraulic pressure release mode, delaying the hydraulic valve operation timing delays the pressure increase operation of the pressure intensifier with respect to the nozzle injection operation. Can be generated. As a result, since the injection is performed before the pressure increase proceeds, the initial stage of the injection can be made low (fuel pressure of the accumulator). Further, micro injection that does not require ultra-high pressure (for example, pilot injection that is performed prior to main injection) can be performed at low pressure (fuel pressure of the accumulator).
The control valve is connected to a valve body driven by an actuator, a back pressure chamber of the nozzle, a switching port connected to the control chamber of the pressure booster via at least a hydraulic valve, and a high pressure chamber of the pressure booster. Alternatively, a high-pressure port connected to the pressure accumulator and a low-pressure port connected to the drain passage on the low-pressure side are provided, and the valve body cuts off between the low-pressure port and the switching port, It is a two-position three-way valve that switches between a hydraulic pressure supply mode that communicates with each other and a hydraulic pressure release mode that shuts off between the high pressure port and the switching port and communicates between the low pressure port and the switching port. Features.
According to the above configuration, the switching port selectively communicates with one of the high-pressure port and the low-pressure port and does not communicate with both ports (the high-pressure port and the low-pressure port) at the same time. Therefore, when the hydraulic pressure release mode is selected, that is, when the fuel pressure in the control chamber and the back pressure chamber is released to the low pressure side, the high pressure port communicating with the high pressure chamber or the accumulator is connected to the switching port and the low pressure port. The gap is blocked by the valve. Thereby, when the hydraulic pressure release mode is selected, the fuel in the pressure accumulator is not allowed to flow down from the control valve to the low pressure side, and energy loss can be suppressed, so that a reduction in fuel consumption of the internal combustion engine can be prevented.
The hydraulic valve has a first port, a second port connected to the control valve switching port, and a third port connected to the pressure accumulator or the high pressure chamber, and the control valve is set to the hydraulic supply mode. Then, the first port and the second port are shut off, the high pressure mode is controlled to communicate between the first port and the third port, and when the control valve is set to the hydraulic release mode, It is characterized by being controlled to a low pressure mode in which the first port and the third port are blocked and the first port and the second port communicate with each other.
Thus, when the hydraulic valve is controlled to the low pressure mode, the fuel pressure in the control chamber is opened to the low pressure side via the control valve, and when the hydraulic valve is controlled to the high pressure mode, the fuel pressure of the accumulator is directly or It is supplied to the control room via the high pressure room.
(Invention of Claim 2)
The fuel injection device for an internal combustion engine according to claim 1, wherein a hydraulic pressure supply passage that bypasses the hydraulic valve and connects the control valve switching port and the control chamber is provided, and the hydraulic pressure supply passage includes a control valve. A check valve is provided to allow the flow of fuel from the valve to the control chamber and prevent its backflow, and the control valve indirectly controls the fuel pressure in the control chamber via the hydraulic valve and the hydraulic supply passage. It is characterized by that.
According to the above configuration, even when the operation of the hydraulic valve is delayed when the control valve is set to the hydraulic supply mode, high-pressure fuel can be supplied from the control valve to the control chamber through the hydraulic supply passage. Regardless of the operation delay, the pressure increasing operation of the pressure intensifier can be immediately terminated.
(Invention of Claim 3)
According to the fuel injection device for an internal combustion engine according to claim 3, the hydraulic valve includes a first port, a second port connected to the drain passage, and a third port connected to the pressure accumulator or the high pressure chamber. And when the control valve is set to the hydraulic pressure supply mode, the first port and the second port are shut off and the first port and the third port are communicated with each other and controlled to the high pressure mode. When the valve is set to the hydraulic pressure release mode, the first port and the third port are blocked and the low pressure mode is controlled to communicate between the first port and the second port.
Thus, when the hydraulic valve is controlled in the low pressure mode, the fuel pressure in the control chamber is opened to the drain passage, and when the hydraulic valve is controlled in the high pressure mode, the fuel pressure in the accumulator is directly or via the high pressure chamber. Supplied to the control room.
In addition, a hydraulic pressure supply passage that connects the control valve switching port and the control chamber is provided, and this hydraulic pressure supply passage allows the flow of fuel from the control valve to the control chamber and prevents backflow. A check valve is provided, and the control valve indirectly controls the fuel pressure in the control chamber via the hydraulic valve and the hydraulic pressure supply passage. According to the above configuration, even when the operation of the hydraulic valve is delayed when the control valve is set to the hydraulic supply mode, high-pressure fuel can be supplied from the control valve to the control chamber through the hydraulic supply passage. Regardless of the operation delay, the pressure increasing operation of the pressure intensifier can be immediately terminated.

(Invention of Claim 4 )
The fuel injection device for an internal combustion engine according to any one of claims 1 to 3, further comprising a pressure introduction path for introducing fuel pressure in accordance with an operation mode of the control valve to the hydraulic valve, and providing a throttle in the pressure introduction path. Thus, the operation of the hydraulic valve is delayed.
By providing a throttle in the pressure introduction path, when the operation mode of the control valve is switched, for example, when the hydraulic pressure supply mode is switched to the hydraulic pressure release mode, the fuel pressure corresponding to the hydraulic pressure release mode is passed through the pressure introduction path. When introduced into the hydraulic valve, introduction of fuel pressure is suppressed by the throttle, so that it is possible to delay the time until the hydraulic valve operates.

(Invention of Claim 5 )
4. The fuel injection device for an internal combustion engine according to claim 1, wherein the operation pressure of the hydraulic valve is set so that the operation of the hydraulic valve is delayed when the operation mode of the control valve is switched. It is characterized by that.
Comparing the case where the operating pressure of the hydraulic valve is large and the case where it is small, the operation timing of the hydraulic valve is delayed when the operating pressure is small compared to when the operating pressure is large. Therefore, by appropriately setting the operating pressure of the hydraulic valve, the operating timing of the hydraulic valve can be delayed when the operating mode of the control valve is switched.

(Invention of Claim 6 )
The fuel injection device for an internal combustion engine according to any one of claims 1 to 3, further comprising a pressure introduction path for introducing fuel pressure in accordance with an operation mode of the control valve to the hydraulic valve, and providing a throttle in the pressure introduction path. In addition, the operation pressure of the hydraulic valve is appropriately set to delay the operation of the hydraulic valve.
By providing a throttle in the pressure introduction path, when the operation mode of the control valve is switched, for example, when the hydraulic pressure supply mode is switched to the hydraulic pressure release mode, the fuel pressure corresponding to the hydraulic pressure release mode is passed through the pressure introduction path. When introduced into the hydraulic valve, introduction of fuel pressure is suppressed by the throttle, so that it is possible to delay the time until the hydraulic valve operates.

Also, when the hydraulic valve operating pressure is large and small, the hydraulic valve operating timing is delayed when the hydraulic pressure is small compared to when the hydraulic pressure is large. Therefore, by appropriately setting the operating pressure of the hydraulic valve, the operating timing of the hydraulic valve can be delayed when the operating mode of the control valve is switched.
Therefore, a delay time until the hydraulic valve is actuated can be arbitrarily set by providing a throttle in the pressure introduction path and appropriately setting the operating pressure of the hydraulic valve.

(Invention of Claim 7 )
The fuel injection device for an internal combustion engine according to any one of claims 1 to 6 , wherein the hydraulic valve operates at a pressure difference between at least a fuel pressure corresponding to an operation mode of the control valve and a fuel pressure of the accumulator. And
Since the fuel pressure corresponding to the operation mode of the control valve is introduced into the hydraulic valve, for example, when the control valve is set to the hydraulic release mode, a low pressure is introduced into the hydraulic valve, and the fuel pressure of the accumulator The differential pressure increases. On the other hand, when the control valve is set to the hydraulic pressure supply mode, a high pressure is introduced into the hydraulic valve, so that the differential pressure from the fuel pressure of the accumulator is small or equal. Thereby, the operation of the hydraulic valve can be controlled using the differential pressure between the fuel pressure introduced according to the operation mode of the control valve and the fuel pressure introduced from the accumulator.

  The best mode for carrying out the present invention will be described in detail by the following examples.

FIG. 1 is a hydraulic circuit diagram of the fuel injection device 1 according to the first embodiment, and FIGS. 2 to 4 are hydraulic circuit diagrams including specific configurations of a control valve 5 and a hydraulic valve 18 used in the fuel injection device 1. .
A fuel injection device 1 according to the present invention is employed in, for example, a common rail system of a diesel engine for a vehicle. As shown in FIG. 1, a pressure accumulator 2 that stores fuel in a predetermined pressure state, and a pressure accumulator 2 A pressure booster 3 that boosts the supplied fuel, a nozzle 4 that injects fuel supplied from the pressure booster 3, a control valve 5 that controls the operation of the pressure booster 3 and the operation of the nozzle 4 are provided. Note that the pressure intensifier 3, excluding the pressure accumulator 2, the nozzle 4, the control valve 5, and the like are integrally configured as one fuel injection valve 6, as shown in FIG.

The pressure accumulator 2 is connected to the fuel injection valve 6 by a fuel pipe 7, and the fuel accumulated in the pressure accumulator 2 is supplied to the fuel injection valve 6 through the fuel pipe 7.
The intensifier 3 has a hydraulic piston 8 in which a large-diameter piston 8a and a small-diameter plunger 8b are provided concentrically. The large-diameter cylinder and the small-diameter cylinder in which the hydraulic piston 8 is formed in a body 9 (see FIG. 5). And is slidably accommodated. In the large-diameter cylinder that accommodates the large-diameter piston 8a, a drive chamber 10 is formed above the upper end surface of the large-diameter piston 8a, and a control chamber 11 is formed below the lower end surface of the large-diameter piston 8a. . On the other hand, in the small diameter cylinder in which the small diameter plunger 8b is accommodated, the high pressure chamber 12 is formed below the lower end surface of the small diameter plunger 8b.

The drive chamber 10 is connected to the fuel pipe 7 through the fuel passage 13, and the fuel pressure of the pressure accumulator 2 is supplied through the fuel pipe 7 and the fuel passage 13. The fuel pressure in the drive chamber 10 acts on the upper end surface of the hydraulic piston 8 and urges the hydraulic piston 8 downward in the figure.
The control chamber 11 is connected to a switching port 40 (see FIG. 2) of the control valve 5 through a reciprocating passage described below. As shown in FIG. 5, the control chamber 11 is provided with a spring 14 for urging the hydraulic piston 8 upward in the drawing.

  As shown in FIG. 1, the reciprocating passage is formed by two fuel passages 15 and 16 that connect the switching port 40 of the control valve 5 and the control chamber 11 in parallel. One fuel passage 15 is provided with a check valve 17 that allows the flow of fuel from the control valve 5 toward the control chamber 11 and prevents the reverse flow, and the other fuel passage 16 includes the fuel passage 16. A hydraulic valve 18 that opens and closes is provided. The two fuel passages 15, 16 may be provided completely independently from one end connected to the switching port 40 of the control valve 5 to the other end connected to the control chamber 11. As shown in FIG. 1, one end side and the other end side of both passages 15 and 16 can be provided in common.

  The high pressure chamber 12 is connected to the fuel pipe 7 through a fuel passage 20 having a check valve 19, and fuel is supplied from the pressure accumulator 2. The check valve 19 allows the flow of fuel (fuel supplied from the pressure accumulator 2) toward the high-pressure chamber 12 through the fuel passage 20 and prevents the reverse flow (flow toward the pressure accumulator 2). The high pressure chamber 12 is connected to the oil sump 4a (see FIG. 5) of the nozzle 4 through the fuel passage 21, and the high pressure port 36 (see FIG. 2) of the control valve 5 and the hydraulic pressure through the fuel passage 22. It is also connected to a third port 47 (see FIG. 2) of the valve 18.

As shown in FIG. 5, the nozzle 4 includes a nozzle body 24 having a nozzle hole 23 formed at the tip, a needle 25 accommodated in the nozzle body 24 so as to reciprocate, and an upper portion of the needle 25 in the figure. The nozzle holder 27 and the like forming the back pressure chamber 26 are arranged at the lower part of the body 9 and fixed to the body 9 by the retainer 28.
An annular fuel passage 29 is formed around the needle 25 in the nozzle body 24, and the oil reservoir 4 a is formed at the upstream end of the fuel passage 29. A conical seat surface (not shown) is formed between the fuel passage 29 and the injection hole 23.

The back pressure chamber 26 is connected to the switching port 40 of the control valve 5 through a fuel passage 30 having a throttle 30a.
When the fuel pressure in the high pressure chamber 12 is supplied to the back pressure chamber 26 via the control valve 5, the needle 25 is urged by the fuel pressure and the spring 31 (see FIG. 5) disposed in the back pressure chamber 26. And is pressed in the valve closing direction (downward in FIG. 5), and a seat line (not shown) provided at the tip of the needle 25 is seated on the seat surface, and the fuel passage 29 and the injection hole 23 Block the gap. On the other hand, when the fuel pressure in the back pressure chamber 26 is released to the low pressure side through the control valve 5, the needle 25 is lifted to open between the fuel passage 29 and the injection hole 23, thereby supplying the oil sump 4a. The fuel to be discharged is injected from the injection hole 23 through the fuel passage 29.

  As shown in FIG. 5, the control valve 5 has a valve chamber 5a formed in the body 32, a valve body 5b accommodated in the valve chamber 5a, and a two-position actuator 33 for driving the valve body 5b. The retainer 34 is disposed on the body 9 and is fixed to the body 9. As shown in FIG. 2, the valve chamber 5 a has a high pressure port 36 to which the fuel pressure of the high pressure chamber 12 is supplied via the fuel passage 22, and a low pressure port 39 that leads to the fuel tank 38 via the drain passage 37. And a switching port 40 connected to the control chamber 11 of the pressure booster 3 through the reciprocating passage (fuel passages 15 and 16) and connected to the back pressure chamber 26 of the nozzle 4 through the fuel passage 30. It has been.

  The valve body 5b shuts off the low pressure port 39 and the switching port 40 and communicates between the high pressure port 36 and the switching port 40 (state shown in FIGS. 1, 2 and 5). The oil pressure release mode (the state shown in FIGS. 3 and 4) in which the high pressure port 36 and the switching port 40 are blocked and the low pressure port 39 and the switching port 40 communicate with each other can be switched. That is, the control valve 5 is configured as a two-position three-way valve that can switch the fuel flow direction in accordance with the operation mode.

  As shown in FIG. 2, the actuator 33 includes a disk-shaped armature 41 connected to the valve body 5b, an electromagnetic coil 43 that is energized and controlled by an electronic control device (hereinafter referred to as ECU 42) mounted on the vehicle, The armature 41 is constituted by a return spring 44 and the like for urging the armature 41 downward in the figure. When a magnetic force is generated by energization of the electromagnetic coil 43, the actuator 33 receives the magnetic force to attract the armature 41 and moves upward in the figure against the reaction force of the return spring 44 to generate a driving force. . When the energization of the electromagnetic coil 43 is stopped, the armature 41 is pushed back by the reaction force of the return spring 44 due to the disappearance of the magnetic force, and returns to the initial state shown in FIG. The hydraulic circuit diagram shown in FIG. 2 shows an example in which the operating direction of the armature 41 is opposite to that in FIG. That is, FIG. 5 shows an example in which the armature 41 moves downward in the figure by receiving a magnetic force when the electromagnetic coil 43 is energized, and FIG. 2 shows an example in which the armature 41 moves upward in the figure.

As shown in FIG. 2, the hydraulic valve 18 includes a valve chamber 18a, a valve body 18b accommodated in the valve chamber 18a, a spring 18c for urging the valve body 18b, and the like.
The valve chamber 18 a has a first port 45 connected to the control chamber 11 of the pressure booster 3, a second port 46 connected to the switching port 40 of the control valve 5, and the pressure booster 3 via the fuel passage 22. A third port 47 connected to the high pressure chamber 12 is provided.
The valve body 18b shuts off between the first port 45 and the second port 46 and communicates between the first port 45 and the third port 47 (shown in FIGS. 2, 3, and 5). State) and a low-pressure mode (state shown in FIG. 4) that communicates between the first port 45 and the second port 46 and blocks between the first port 45 and the third port 47. it can.
The spring 18c is accommodated in a working chamber 18d that is recessed below the valve chamber 18a, and urges the valve body 18b to the high pressure mode side (upward in FIG. 2).

  The hydraulic valve 18 is always supplied with the fuel pressure of the accumulator 2 via the fuel passage 48 connected to the fuel pipe 7, and the fuel pressure applies the valve body 18b to the low pressure mode side (downward in FIG. 2). It is fast. In addition, fuel pressure corresponding to the operation mode of the control valve 5 is introduced into the working chamber 18d through a pressure introduction path 49 connected to the switching port 40 of the control valve 5. In other words, when the control valve 5 is set to the hydraulic pressure supply mode, the fuel pressure in the high pressure chamber 12 is introduced into the working chamber 18d from the pressure introduction path 49, and the force that biases the valve body 18b to the low pressure mode side and the high pressure mode. Since the difference from the force urging to the side is small or equal, the valve body 18b is urged by the spring 18c to enter the high pressure mode.

On the other hand, when the control valve 5 is set to the hydraulic pressure release mode, the differential pressure applied to the valve body 18b increases due to the working chamber 18d leading to the low pressure side (the force for urging the valve body 18b to the low pressure mode side). Therefore, the valve body 18b is urged toward the low pressure mode against the reaction force of the spring 18c to enter the low pressure mode. That is, the hydraulic valve 18 is configured as a two-position three-way valve that switches between the high pressure mode and the low pressure mode according to the operation mode of the control valve 5.
However, when the control valve 5 is switched from the hydraulic pressure supply mode to the hydraulic pressure release mode, a restriction 50 (see FIGS. 1 and 2) is provided in the pressure introduction path 49 so that a delay occurs in the timing at which the hydraulic valve 18 is switched from the high pressure mode to the low pressure mode. Reference) is provided.

Next, the operation of the fuel injection device 1 will be described based on the time charts shown in FIGS. 2 to 4 and 6. Note that (1), (2), and (3) in FIG. 6 correspond to the states shown in FIGS. 2, 3, and 4, respectively.
When the electromagnetic coil 43 of the actuator 33 is in the OFF state, the control valve 5 is set to the hydraulic pressure supply mode as shown in FIG. In this hydraulic pressure supply mode, the switching port 40 and the low pressure port 39 are disconnected, and the high pressure port 36 and the switching port 40 communicate with each other. As a result, the high pressure chamber 12 of the pressure intensifier 3 and the back pressure chamber 26 of the nozzle 4 communicate with each other via the control valve 5. 26.

  The hydraulic valve 18 has a valve body because the fuel pressure introduced through the fuel passage 48 and the fuel pressure introduced through the pressure introduction passage 49 have the same high pressure (fuel pressure of the accumulator 2). 18b is urged by the spring 18c to be controlled to the high pressure mode. As a result, the fuel pressure of the pressure accumulator 2 is supplied to the control chamber 11 of the pressure booster 3 through the one fuel passage 15 and the hydraulic valve 18. At this time, since the fuel pressure of the pressure accumulator 2 is also supplied to the drive chamber 10 in the pressure intensifier 3, the fuel pressure acting on the upper and lower end faces of the hydraulic piston 8 is balanced. As a result, the hydraulic piston 8 is biased by the spring 14 (see FIG. 5) and moves upward in the drawing, and the high pressure chamber 12 is filled with fuel as the volume of the high pressure chamber 12 increases. In this state, the back pressure chamber 26 of the nozzle 4 has the same fuel pressure as that of the high pressure chamber 12, that is, the fuel pressure of the accumulator 2, so that the needle 25 does not lift, and the fuel passage 29 in the nozzle 4 Since the space between the nozzle holes 23 is blocked, fuel is not injected.

Next, when a drive signal (see FIG. 6A) is output from the ECU 42 to the actuator 33 and the electromagnetic coil 43 is energized, as shown in FIG. 3, the control valve 5 changes from the hydraulic pressure supply mode to the hydraulic pressure release mode. Switch. In this hydraulic pressure release mode, the high pressure port 36 and the switching port 40 are disconnected, and the switching port 40 and the low pressure port 39 communicate with each other. As a result, the back pressure chamber 26 of the nozzle 4 communicates with the drain passage 37 on the low pressure side, and the fuel pressure in the back pressure chamber 26 is released, so that the needle 25 is lifted and the fuel supplied to the oil sump 4a. Is ejected from the nozzle hole 23.
At this time, the hydraulic valve 18 maintains the high pressure mode shown in FIG. 3 until the fuel pressure in the back pressure chamber 26 drops to a predetermined pressure. 8 will not operate. Therefore, the injection pressure of the nozzle 4 is not the ultrahigh pressure increased by the pressure booster 3 but is substantially equal to the fuel pressure of the pressure accumulator 2.

  Thereafter, the fuel pressure in the back pressure chamber 26 decreases to a predetermined pressure, and the hydraulic valve 18 is switched from the high pressure mode to the low pressure mode after a delay time set by the throttle 50 of the pressure introduction passage 49 (see FIG. 4). ). As a result, the control chamber 11 of the intensifier 3 and the switching port 40 of the control valve 5 communicate with each other via the hydraulic valve 18, so that the fuel pressure in the control chamber 11 is released to the low pressure side. As a result, since the pressure balance between the upper side and the lower side acting on the hydraulic piston 8 is lost, the hydraulic piston 8 is pressed down by the fuel pressure in the drive chamber 10.

  Along with the pressure increasing operation of the hydraulic piston 8, the fuel pressure in the high pressure chamber 12 starts to increase, and finally the pressure is increased according to the cross-sectional area ratio between the large diameter piston 8a and the small diameter plunger 8b. For example, when the fuel pressure of the accumulator 2 is 50 MPa and the cross-sectional area ratio between the large diameter piston 8a and the small diameter plunger 8b is set to 4: 1, the fuel pressure in the high pressure chamber 12 is 4 × 50 = 200 MPa. As a result, the ultra-high pressure fuel boosted by the pressure booster 3 is injected from the nozzle 4. When pilot injection (microinjection) is performed prior to main injection, by returning from the state of FIG. 3 to the state of FIG. 2 immediately, injection at a low pressure is possible before the pressure increase proceeds. . Further, in the main injection, by continuing the state of FIG. 4 and proceeding with the pressure increasing operation, it is possible to perform injection at an ultrahigh pressure.

Thereafter, when energization to the electromagnetic coil 43 is stopped at a predetermined timing (for example, when a predetermined injection amount is reached), the control valve 5 is switched from the hydraulic pressure release mode to the hydraulic pressure supply mode. The high pressure (fuel pressure of the accumulator 2) is supplied to 26 and the needle 25 is pushed back, whereby the injection by the nozzle 4 is completed.
On the other hand, the pressure intensifier 3 is controlled by one fuel passage 15 that bypasses the hydraulic valve 18 although the hydraulic valve 18 is operated with a delay after the operation mode of the control valve 5 is switched (the low pressure mode is switched to the high pressure mode). Since the chamber 11 and the switching port 40 of the control valve 5 are directly connected, regardless of the state of the hydraulic valve 18, when the control valve 5 is switched from the hydraulic release mode to the hydraulic supply mode, it passes through one fuel passage 15. Thus, a high pressure (fuel pressure of the accumulator 2) is supplied to the control chamber 11. As a result, as the pressure in the control chamber 11 increases, the hydraulic piston 8 immediately stops the pressure increasing operation and starts the return stroke. Thereafter, the hydraulic valve 18 is switched to the high pressure mode with a delay, and this continues to supply high pressure to the control chamber 11.
FIG. 7 shows the result of numerical analysis by computer simulation. However, this is an example in which the cross-sectional area ratio of the hydraulic piston 8 is 2: 1. According to this simulation, it can be seen that substantially the same operation and performance as those described above can be obtained.

(Effect of Example 1)
The fuel injection device 1 described in the first embodiment includes two fuel passages 15 and 16 that connect the switching port 40 of the control valve 5 and the control chamber 11 of the pressure booster 3. The two fuel passages 15 and 16 can be properly used according to the operation mode. That is, when the control valve 5 is set to the hydraulic release mode, the hydraulic valve 18 provided in the other fuel passage 16 is controlled to the low pressure mode, so that the control chamber 11 passes through the other fuel passage 16 from the control chamber 11 to the low pressure side. The pressure can be released. One fuel passage 15 is provided with a check valve 17 that prevents the flow of fuel from the control chamber 11 toward the control valve 5, so that the fuel pressure in the control chamber 11 passes through the one fuel passage 15. Therefore, it is not opened to the low pressure side.

Further, when the control valve 5 is set to the hydraulic pressure supply mode, the hydraulic valve 18 is controlled to the high pressure mode, so that the control chamber 11 passes through the fuel passage 15 and the hydraulic valve 18 to the control chamber 11 with high pressure (the fuel in the accumulator 2). Pressure).
According to the above configuration, the speed at which the fuel pressure in the control chamber 11 is released (pressure release speed) and the speed at which fuel pressure is supplied to the control chamber 11 (pressurization speed) can be individually controlled. As shown in FIG. 6 (f), the pressure increase speed (the broken line A in the figure) of the pressure intensifier 3 can be changed according to the pressure release speed, and the return speed of the pressure intensifier 3 is changed according to the pressure speed. Can be changed (broken line B in the figure).

  Moreover, in Example 1, since the throttle 50 is provided in the pressure introduction path 49 leading to the working chamber 18d of the hydraulic valve 18, the broken lines in FIGS. 6D and 6E correspond to the mode switching of the control valve 5. As indicated by C, the timing of mode switching of the hydraulic valve 18 can be delayed. As a result, it is possible to delay the operation of the pressure booster 3 (pressure increase start timing). In this way, by changing the pressure increase speed of the pressure booster 3, the return speed of the pressure booster 3, and the pressure increase start time of the pressure booster 3, as shown in FIG. This makes it possible to optimize the injection rate pattern. As is well known, this optimization of the injection rate pattern is effective for exhaust gas purification and output improvement of an internal combustion engine. Further, by changing the return speed of the intensifier 3, particularly in a high-speed internal combustion engine, setting such as increasing the time for returning to the initial position becomes possible without affecting other characteristics.

Furthermore, by delaying the pressure increase start timing of the pressure intensifier 3, the initial stage of injection can be made low pressure, the period can be changed by the throttle 50, and a minute injection (for example, pilot injection) that does not require super high pressure can be performed. At times, since the time for the injection state is extremely short, it is possible to inject at a pressure that is not pressurized (fuel pressure of the accumulator 2).
In the control valve 5 described in the first embodiment, for example, when the hydraulic pressure supply mode is switched to the hydraulic pressure release mode, the high-pressure port 36 and the low-pressure port 39 are temporarily in communication with each other. Since no fuel dripping occurs except for a slight switching leak, energy loss can be suppressed and fuel consumption reduction of the internal combustion engine can be prevented.

Furthermore, as described above, since the end of the pressure increasing operation can be performed substantially simultaneously with the end of the injection operation, it is not necessary to operate the pressure intensifier 3 wastefully, and waste of driving energy can be eliminated.
As described above, the fuel injection device 1 described in the first embodiment can achieve ultra-high pressure injection with little loss with a simple configuration using only one control valve 5 driven by the two-position actuator 33, and Various injection patterns such as low-pressure and ultrahigh-pressure injection can be realized. In addition, since the operation of the intensifier 3 can be optimized, it is possible to create optimum injection characteristics and to optimize the return time.

(Modification)
In the first embodiment, a throttle 50 is provided in the pressure introduction path 49 to delay the operation of the pressure booster 3 (pressure increase start timing) by delaying the timing at which the hydraulic valve 18 switches from the high pressure mode to the low pressure mode. However, the delay time can be adjusted by appropriately setting the operating pressure of the hydraulic valve 18 instead of providing the throttle 50. For example, the delay time can be set by the load of the spring 18c that biases the valve body 18b of the hydraulic valve 18. Alternatively, the timing at which the hydraulic valve 18 operates can be delayed by the cooperation of the effect of the throttle 50 provided in the pressure introduction path 49 and the operating pressure of the hydraulic valve 18.

FIG. 8 is a hydraulic circuit diagram of the fuel injection device 1 according to the second embodiment.
The fuel injection device 1 shown in the second embodiment is an example in which the third port 47 of the hydraulic valve 18 is connected to the pressure accumulator 2, and other configurations are the same as those of the first embodiment.
In the configuration of the second embodiment, when the hydraulic piston 8 of the pressure booster 3 is restored, that is, when the hydraulic valve 18 is switched from the low pressure mode to the high pressure mode, the pressure accumulator is not passed through the high pressure chamber 12 of the pressure booster 3. Since pressure can be supplied from 2 to the control chamber 11 via the hydraulic valve 18, the return of the hydraulic piston 8 is more stable and reliable.

FIG. 9 is a hydraulic circuit diagram of the fuel injection device 1 according to the third embodiment.
In the fuel injection device 1 shown in the third embodiment, the third port 47 of the hydraulic valve 18 is connected to the accumulator 2 and the high-pressure port 36 of the control valve 5 is connected to the accumulator 2 as in the second embodiment. The other configuration is the same as that of the first embodiment.
In the configurations of the first and second embodiments, the fuel pressure of the pressure accumulator 2 is supplied to the high pressure port 36 of the control valve 5 via the high pressure chamber 12, but in the configuration of the present embodiment, the fuel of the pressure accumulator 2 is supplied. The pressure is supplied directly to the high pressure port 36 without going through the high pressure chamber 12. As a result, since the pressure supply to the back pressure chamber 26 of the nozzle 4 is more stable, the nozzle 4 is reliably operated.
Further, since the increased ultrahigh pressure in the high pressure chamber 12 is not used for control, the pressure loss can be reduced.

FIG. 10 is a hydraulic circuit diagram of the fuel injection device 1 according to the fourth embodiment.
The fuel injection device 1 shown in the fourth embodiment is an example in which the fuel passage 15 and the check valve 17 described in the first embodiment are omitted, and other configurations are the same as those in the first embodiment.
The hydraulic valve 18 of the present invention is configured as a two-position three-way valve that switches between the low pressure mode and the high pressure mode, and the high pressure port 36 of the control valve 5 and the third port 47 of the hydraulic valve 18 are constantly at high pressure, so When the valve 5 is set to the hydraulic pressure supply mode (the state shown in FIG. 10), high pressure (fuel pressure of the accumulator 2) is supplied to the first port 45 of the hydraulic valve 18 regardless of the operating state of the hydraulic valve 18. Is done.

  That is, since the hydraulic valve 18 operates with a predetermined delay time when the operation mode of the control valve 5 is switched, for example, when the control valve 5 is switched from the hydraulic release mode to the hydraulic supply mode, the hydraulic valve 18 Temporarily maintains the low pressure mode. At this time, the hydraulic valve 18 communicates between the first port 45 and the second port 46, and the second port 46 and the switching port 40 of the control valve 5 are directly connected. The high pressure supplied to the switching port 40 is also supplied to the first port 45 of the hydraulic valve 18. Thereafter, when the hydraulic valve 18 is switched from the low pressure mode to the high pressure mode after a predetermined delay time, a high pressure is supplied to the first port 45 via the high pressure chamber 12 connected to the third port 47.

Therefore, when the control valve 5 is switched from the hydraulic pressure release mode to the hydraulic pressure supply mode at the end of injection, a high pressure is supplied to the first port 45 of the hydraulic valve 18 regardless of the operating state of the hydraulic valve 18, and the high pressure is increased. By being supplied to the third control chamber 11, the pressure increasing operation can be immediately terminated.
Thereby, the fuel passage 15 and the check valve 17 described in the first embodiment can be eliminated, and the circuit configuration can be simplified.

FIG. 11 is a hydraulic circuit diagram of the fuel injection device 1 according to the fifth embodiment.
The fuel injection device 1 shown in the fifth embodiment is an example in which the fuel passage 15 and the check valve 17 described in the third embodiment are eliminated, and other configurations are the same as those in the third embodiment.
As in the case of the fourth embodiment, when the control valve 5 switches from the hydraulic release mode to the hydraulic supply mode at the end of injection, high pressure is supplied to the first port 45 of the hydraulic valve 18 regardless of the operating state of the hydraulic valve 18. Then, when the high pressure is supplied to the control chamber 11 of the pressure booster 3, the pressure increase operation can be immediately terminated. Thereby, the fuel passage 15 and the check valve 17 described in the third embodiment can be eliminated, and the circuit configuration can be simplified.

FIG. 12 is a hydraulic circuit diagram of the fuel injection device 1 according to the sixth embodiment.
In the fuel injection device 1 shown in the sixth embodiment, the second port 46 of the hydraulic valve 18 is connected to the drain passage 37 on the low pressure side, and other configurations are the same as those in the first embodiment.
In this case, when the control valve 5 is in the hydraulic pressure release mode, it is not necessary to pass the fuel flowing out from the control chamber 11 of the pressure booster 3 through the control valve 5, so that the control valve 5 is smaller than the configuration of the first embodiment. Can be When the control valve 5 is in the hydraulic pressure supply mode, the fuel supplied to the control chamber 11 passes through the control valve 5. However, when the fuel is supplied to the control chamber 11, the required time is longer than when the fuel flows out. Even if 5 is downsized, there is no restriction.

1 is a hydraulic circuit diagram of a fuel injection device (Example 1). 1 is a hydraulic circuit diagram including specific configurations of a control valve and a hydraulic valve used in a fuel injection device (Example 1). 1 is a hydraulic circuit diagram of a fuel injection device (Example 1). 1 is a hydraulic circuit diagram of a fuel injection device (Example 1). 1 is an overall cross-sectional view showing a structure of a fuel injection valve (Example 1). It is a time chart which concerns on the action | operation of a fuel-injection apparatus (Example 1). It is a graph which shows the result of having analyzed numerically the operation | movement of the fuel-injection apparatus by simulation (Example 1). (Example 2) which is the hydraulic circuit figure of a fuel-injection apparatus. (Example 3) which is a hydraulic circuit diagram of a fuel-injection apparatus. (Example 4) which is a hydraulic circuit diagram of a fuel-injection apparatus. (Example 5) which is a hydraulic circuit diagram of a fuel-injection apparatus. (Example 6) which is a hydraulic circuit diagram of a fuel-injection apparatus. 1 is a hydraulic circuit diagram of a fuel injection device (prior art).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection device for internal combustion engines 2 Pressure accumulator 3 Pressure booster 4 Nozzle 5 Control valve 5b Valve body of control valve 8 Hydraulic piston 11 Control chamber of pressure booster 12 High pressure chamber of pressure booster 15 One fuel passage (hydraulic supply passage)
16 Other fuel passage (fuel passage for releasing the fuel pressure in the control chamber to the low pressure side)
17 Check valve provided in one fuel passage 18 Hydraulic valve 18b Valve body of hydraulic valve 25 Needle 26 Back pressure chamber of nozzle 33 Two-position actuator 36 High pressure port of control valve 37 Drain passage 39 Low pressure port of control valve 40 Control Valve switching port 45 Hydraulic valve first port 46 Hydraulic valve second port 47 Hydraulic valve third port 49 Pressure introduction path 50 Restriction provided in pressure introduction path

Claims (7)

a) a pressure accumulator for storing fuel in a predetermined pressure state;
b) a control chamber in which fuel pressure increases or decreases due to inflow or outflow of fuel; a high pressure chamber to which fuel is supplied from the accumulator; and a hydraulic piston that moves according to increase or decrease in fuel pressure in the control chamber; A pressure intensifier for increasing the pressure of the fuel in the high pressure chamber by the pressure increasing operation of the hydraulic piston;
c) a back pressure chamber in which the fuel pressure increases or decreases due to the inflow or outflow of fuel, and a needle that moves according to the increase or decrease in the fuel pressure in the back pressure chamber, and the fuel supplied via the pressure intensifier A nozzle that injects by opening the needle;
d) a hydraulic pressure supply mode driven by a single two-position actuator to supply fuel pressure in the accumulator or the high pressure chamber to the control chamber and the back pressure chamber; and fuel pressure in the control chamber and the back pressure chamber. A control valve that switches between a hydraulic release mode that opens to the low pressure side;
e) having a first port connected to the control chamber and operating by introducing a fuel pressure according to the operation mode of the control valve, thereby connecting the first port to the high pressure side and the low pressure side; A hydraulic valve configured as a three-way valve to switch to either one of
The control valve controls the injection operation of the nozzle by directly controlling the fuel pressure in the back pressure chamber, and indirectly controls the fuel pressure in the control chamber through at least the hydraulic valve. A fuel injection device for an internal combustion engine for controlling a pressure increasing operation of a pressure intensifier,
With respect to the injection operation of the nozzle, the operation timing of the hydraulic valve is delayed so that a delay occurs in the pressure increase operation of the pressure intensifier ,
The control valve is connected to a valve body driven by the actuator, a back pressure chamber of the nozzle, a switching port connected to the control chamber of the pressure booster via at least the hydraulic valve, and the booster. A high-pressure port connected to the high-pressure chamber of the pressure device or the accumulator, and a low-pressure port connected to the drain passage on the low-pressure side, the valve body blocking between the low-pressure port and the switching port The hydraulic pressure supply mode for communicating between the high pressure port and the switching port, and the valve body shuts off between the high pressure port and the switching port, and between the low pressure port and the switching port. A two-position three-way valve that switches between communicating with the hydraulic release mode;
The hydraulic valve includes the first port, a second port connected to the switching port of the control valve, and a third port connected to the pressure accumulator or the high pressure chamber. When the hydraulic pressure supply mode is set, the control valve is controlled to a high pressure mode in which the first port and the second port are disconnected and the first port and the third port communicate with each other. Is set to the hydraulic pressure release mode, the first port and the third port are disconnected, and the first port and the second port are controlled to be in a low pressure mode. A fuel injection device for an internal combustion engine. The fuel injection device for an internal combustion engine according to claim 1,
A hydraulic pressure supply passage that bypasses the hydraulic valve and connects the control valve switching port and the control chamber is provided, and a flow of fuel from the control valve to the control chamber is provided in the hydraulic pressure supply passage. Is provided with a check valve that prevents backflow,
The fuel injection device for an internal combustion engine , wherein the control valve indirectly controls the fuel pressure in the control chamber via the hydraulic valve and the hydraulic pressure supply passage . a) a pressure accumulator for storing fuel in a predetermined pressure state;
b) a control chamber in which fuel pressure increases or decreases due to inflow or outflow of fuel; a high pressure chamber to which fuel is supplied from the accumulator; and a hydraulic piston that moves according to increase or decrease in fuel pressure in the control chamber; A pressure intensifier for increasing the pressure of the fuel in the high pressure chamber by the pressure increasing operation of the hydraulic piston;
c) a back pressure chamber in which the fuel pressure increases or decreases due to the inflow or outflow of fuel, and a needle that moves according to the increase or decrease in the fuel pressure in the back pressure chamber, and the fuel supplied via the pressure intensifier A nozzle that injects by opening the needle;
d) a hydraulic pressure supply mode driven by a single two-position actuator to supply fuel pressure in the accumulator or the high pressure chamber to the control chamber and the back pressure chamber; and fuel pressure in the control chamber and the back pressure chamber. A control valve that switches between a hydraulic release mode that opens to the low pressure side;
e) having a first port connected to the control chamber and operating by introducing a fuel pressure according to the operation mode of the control valve, thereby connecting the first port to the high pressure side and the low pressure side; A hydraulic valve configured as a three-way valve to switch to either one of
The control valve controls the injection operation of the nozzle by directly controlling the fuel pressure in the back pressure chamber, and indirectly controls the fuel pressure in the control chamber through at least the hydraulic valve. A fuel injection device for an internal combustion engine for controlling a pressure increasing operation of a pressure intensifier,
With respect to the injection operation of the nozzle, the operation timing of the hydraulic valve is delayed so that a delay occurs in the pressure increase operation of the pressure intensifier,
The control valve is connected to a valve body driven by the actuator, a back pressure chamber of the nozzle, a switching port connected to the control chamber of the pressure booster via at least the hydraulic valve, and the booster. A high-pressure port connected to the high-pressure chamber of the pressure device or the accumulator, and a low-pressure port connected to the drain passage on the low-pressure side, the valve body blocking between the low-pressure port and the switching port The hydraulic pressure supply mode for communicating between the high pressure port and the switching port, and the valve body shuts off between the high pressure port and the switching port, and between the low pressure port and the switching port. A two-position three-way valve that switches between communicating with the hydraulic release mode;
The hydraulic valve has the first port, a second port connected to the drain passage, and a third port connected to the accumulator or the high pressure chamber, and the control valve is in the hydraulic supply mode. Is set to a high pressure mode in which the first port and the second port are disconnected and the first port and the third port communicate with each other, and the control valve is controlled by the hydraulic pressure. When set to the open mode, the first port and the third port are shut off, and the first port and the second port are communicated with each other, and the low pressure mode is controlled.
A hydraulic pressure supply passage is provided to connect between the control valve switching port and the control chamber. The hydraulic pressure supply passage allows the flow of fuel from the control valve to the control chamber and prevents the reverse flow. A fuel injection device for an internal combustion engine, comprising a check valve for preventing the internal combustion engine. The fuel injection device for an internal combustion engine according to any one of claims 1 to 3 ,
A pressure introduction path for introducing fuel pressure in accordance with the operation mode of the control valve to the hydraulic valve, and providing a throttle in the pressure introduction path to delay the operation of the hydraulic valve ; A fuel injection device for an internal combustion engine. The fuel injection device for an internal combustion engine according to any one of claims 1 to 3 ,
The fuel injection device for an internal combustion engine , wherein the operation pressure of the hydraulic valve is set so that the operation of the hydraulic valve is delayed when the operation mode of the control valve is switched . The fuel injection device for an internal combustion engine according to any one of claims 1 to 3 ,
A pressure introduction path for introducing fuel pressure in accordance with the operation mode of the control valve to the hydraulic valve; providing a throttle in the pressure introduction path; and appropriately setting the operating pressure of the hydraulic valve, A fuel injection device for an internal combustion engine characterized by delaying the operation of a hydraulic valve . The fuel injection device for an internal combustion engine according to any one of claims 1 to 6 ,
The fuel injection device for an internal combustion engine , wherein the hydraulic valve is operated by a differential pressure between a fuel pressure corresponding to at least an operation mode of the control valve and a fuel pressure of the accumulator .

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