JP2005105870A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a plurality of injection patterns with simple construction having a single actuator, and conduct an injection control with an inexpensive system with an excellent response and high precision. <P>SOLUTION: Fuel fed from an accumulator 10 into a high pressure chamber 24 is pressurized by drive of a booster cylinders 21, 22, and injected from an injection nozzle 30. A control valve 100 driven with a two-position electromagnetic actuator 130 to offer two control functions is provided. The control valve 100 is comprised of a pressure boosting control valve part 110 to control a boosting operation of a booster 20, and an injection control valve 120 to control an injection operation of the injection nozzle 30. Both the two control function parts 110, 120 are comprised of a two-position two-way valve. Two control function parts 110, 120 are formed to possess a time lag in the operations so that boosting control start with the boosting control valve 110 is earlier than injection control start with the injection control valve part 120, and boosting control end is later than the injection control end. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection device for an internal combustion engine, particularly a diesel engine, and more particularly to a fuel injection device provided with a pressure increasing mechanism.

  A common rail system has attracted attention as a fuel injection device for diesel engines. The common rail system is a system that provides a common pressure accumulator (common rail), stores pressurized fuel pumped from a fuel supply pump, and opens and closes the injection nozzle with a hydraulic control valve and injects it into each cylinder. Excellent performance, such as the amount can be controlled independently.

In recent years, there has been a demand for higher performance of such a common rail system from the viewpoint of exhaust gas purification and fuel efficiency improvement. Specifically, it is necessary to increase the fuel injection pressure. In order to realize this easily, for example, a new system having a pressure increasing mechanism as described in Patent Document 1 has been proposed.
Japanese Patent No. 2885076

  The fuel injection device of Patent Document 1 includes a pressure increase mechanism that increases the pressure of the fuel in the pressure accumulator, and a mechanism that hydraulically controls nozzle opening and closing, which is an advantage of the common rail system. In this device, not only can a pressure increase mechanism be used to inject at a higher pressure, but both the pressure increase and the injection can be controlled to achieve a plurality of injection modes such as a micro injection at a low pressure and a main injection at an ultra high pressure. And the injection pressure can be changed in one injection cycle. Therefore, fine control according to the operating state can be performed to optimize the combustion.

  However, in this type of system, since it is necessary to control two operations, that is, a pressure increasing operation and an injection operation independently, at least two actuators are required, and the system configuration is complicated. It is easy to become. For this reason, there exists a problem that cost becomes high, and it is desired to implement | achieve an equivalent function more simply.

  Necessary operations include a mode in which the pressure in the accumulator is injected as it is without increasing the pressure, and a mode in which the pressure is increased and injected at an ultrahigh pressure. In the present invention, these operations can be realized with a simple configuration of one actuator, and in addition, in order to prevent performance degradation such as a decrease in injection pressure caused by using one actuator, the response of the control valve is increased, Another object of the present invention is to provide a high-performance and inexpensive system as a configuration capable of performing timing control with high accuracy.

In the invention of claim 1, the fuel injection device for an internal combustion engine comprises:
An accumulator for accumulating fuel;
A pressure intensifier for increasing the pressure of the fuel supplied from the pressure accumulator to the high pressure chamber by driving the pressure increasing piston;
Opening / closing is controlled by increasing / decreasing the hydraulic pressure of the back pressure chamber, and includes an injection nozzle that injects fuel directly supplied from the accumulator or fuel increased in pressure by the intensifier,
Driven by one two-position electromagnetic actuator to perform two control functions, one of which is a pressure-increasing control valve unit for controlling the pressure-increasing operation of the pressure intensifier, and the other is an injection control valve for controlling the injection operation of the injection nozzle It has a control valve that is a part.
In the control valve, both of the two control function units have the function of a two-position two-way valve, and the start of the pressure increase operation control by the pressure increase control valve unit is the injection operation control by the injection control valve unit. The operation of the two control function units has a deviation so that the end of the pressure increase operation control by the pressure increase control valve unit is earlier than the end of the injection operation control by the injection control valve unit earlier than the start of is there.

  In the above configuration, when the two-position electromagnetic actuator is energized, first, the pressure increase control valve portion of the control valve starts the pressure increase control. The pressure increase control valve portion has a two-position two-way valve structure, and drives the pressure increase piston by opening and closing between the control chamber of the pressure increaser and the fuel return passage. Next, the injection control valve portion having the two-position two-way valve structure opens and closes between the back pressure chamber of the injection nozzle and the fuel return passage to start injection control. When the energization to the actuator is stopped, the injection control ends first, and then the pressure increase control ends.

  Thus, by providing a deviation in the operation of the two control function units, the delay of the pressurization and pressurization due to the system operation delay is eliminated, and the decrease in the injection pressure at the end of the injection is prevented. Allows injection of. Further, if injection is performed for a short time before the pressure increase proceeds, minute injection at a low pressure is possible.

  Accordingly, two operations of pressure increase and injection are controlled by one actuator and one valve body, and an injection pattern such as main injection at an ultrahigh pressure and micro injection at a low pressure is possible with a simple configuration. The actuator is an inexpensive electromagnetic actuator that can be combined with a simple control valve with a two-position two-way valve structure to reduce the overall cost of the system, and it is an inexpensive system with high responsiveness and high accuracy. Can be performed.

  According to a second aspect of the present invention, the control valve is configured to always balance the pressure in the operation direction. By balancing the pressure, the required attractive force of the electromagnetic actuator can be reduced and the structure can be reduced.

  According to a third aspect of the present invention, the movable member of the control valve is composed of one valve body directly connected to the electromagnetic actuator. By providing a single valve element and a two-position electromagnetic actuator, control can be performed with a simple structure and good response.

  According to a fourth aspect of the present invention, the movable member of the control valve has a spool valve shape having a cylindrical seal portion. When a spool valve is used, the configuration of the two control function units is easy, the pressure balance structure is easy to adopt, and the size can be reduced.

  According to a fifth aspect of the present invention, the control edge of the cylindrical seal portion of the movable member is brought into the pressure increasing operation control state prior to the injection operation control according to the lift of the movable member, and the injection operation control according to the return lift. It arrange | positions so that it may be in the completion | finish state of pressure increase operation | control control later.

  Specifically, in the spool valve constituting the control valve, the timing of communication / blocking of the flow path is set by appropriately setting the positions of the edge of the cylindrical seal portion that controls the injection operation and the edge that controls the pressure increase operation. The desired control state can be realized by shifting.

  According to a sixth aspect of the present invention, the movable member of the control valve comprises two valve bodies, one of which is the first valve body that controls the pressure-increasing operation of the pressure-increasing control valve section, and the other is the injection control valve. The first valve body is directly connected to the electromagnetic actuator as a second valve body for controlling the injection operation of the part. The second valve body is driven by the driving force of the electromagnetic actuator via the first valve body.

  The movable member of the control valve can also be composed of two valve bodies. In this case, there is an advantage that an operation deviation can be easily set by adjusting a gap between the two valve bodies.

  In a seventh aspect of the invention, the movable member of the control valve has a cone sheet or a flat sheet. Since the sealing performance is improved by changing the seal structure to a cone sheet or a flat sheet, the axial seal length can be eliminated, and the required lift can be reduced, so that the control valve can be miniaturized.

  In the invention according to claim 8, in the initial state where the two valve bodies of the control valve are arranged coaxially, the two valve bodies are both seated, and in the pressure increasing operation stop state and the injection operation stop state, respectively. A gap corresponding to the displacement of the operation is provided between the two valve bodies.

  When the electromagnetic actuator is energized from this initial state, the first valve body integrated with the electromagnetic actuator is lifted to start the pressure increasing operation control of the pressure increasing control valve portion. When the clearance is lifted, the first valve body comes into contact with the second valve body, and thereafter, the first valve body lifts together. That is, the gap between the operations of the two valve bodies can be adjusted by the gap between the two valve bodies.

  According to the ninth aspect of the present invention, the gap between the two valve bodies of the control valve is set by adjusting the seat position of at least one of the valve bodies, adjusting the length between the seat and the contact end surface, or adjusting the shim.

  The gap that causes the operation deviation can be easily set by adjusting the position where the seat surface of at least one valve body is seated or adjusting the distance between the contact end surfaces from the seat. Alternatively, by using a shim to adjust the distance between the two valve bodies, a gap corresponding to a shift in operation can be easily set without changing the valve body shape.

  The present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of a fuel injection device of the present invention, which is embodied as a fuel injection device applied to a common rail system of a vehicle diesel engine. As shown in FIG. 1, the fuel injection device 1 includes, as main components, a pressure accumulator (common rail) 10 that accumulates fuel, a pressure intensifier 20 that boosts fuel from the pressure accumulator 10, and a pressure accumulator 10. And the control valve 100 for controlling the operation of the pressure intensifier 20 and the injection nozzle 30. Further, fuel passages 6, 61 to 64 communicating with these components and fuel return passages 7, 71, 72 reaching the fuel tank T are provided, and a check valve 40 and several throttles 51 are provided in the middle of the fuel passage. , 52, 53, 54 are disposed.

  The pressure booster 20 has a pressure boosting piston composed of a large diameter piston 21 and a small diameter plunger 22, and boosts the fuel supplied from the pressure accumulator 10 to the high pressure chamber 24 via the check valve 40. The injection nozzle 30 is controlled to open and close by increasing or decreasing the hydraulic pressure in the back pressure chamber 34 communicating with the high pressure chamber 24. The control valve 100 shown generally has two control function units, one of which is a pressure-increasing control valve unit 110 for controlling the pressure-increasing operation of the pressure-intensifier 20, and the other is controlling the injection operation by the injection nozzle 30. It becomes the injection control valve part 120 which performs. Here, the function is divided into two parts for convenience, but these are driven by one two-position actuator 130. Both the pressure increase control valve part 110 and the injection control valve part 120 are two-position two-way valves. It has the function of

  2 to 5 show a first embodiment of the present invention. FIG. 2 is a detailed configuration example of the control valve 100 of FIG. 1, and an example of the overall configuration of the fuel injection device 1 including the control valve 100 is shown in FIG. In FIG. 5, the fuel injection device 1 injects the first body B1 and the second body B2 in which the control valve 100 is accommodated in the upper end side of the body B in which the pressure intensifier 20 is accommodated in the lower end side of the body B. A third body B3 and a fourth body B4 that constitute the nozzle 30 are disposed, and are fixed oil-tight by retainers 201 and 202. A fuel introduction pipe 203 (left side in FIG. 1) to which the fuel passage 6 leading to the pressure accumulator 10 is connected and a fuel lead-out pipe 204 to which a fuel return passage 7 leading to the fuel tank T is connected to the side of the body B. (The right side of FIG. 1) is formed to protrude.

  The pressure accumulator 10 is supplied with fuel pressurized by a known fuel pump (not shown) having a variable discharge mechanism. The pressure of the fuel stored in the pressure accumulator 10 is controlled by changing the discharge amount from the fuel pump by a control device (not shown). Thus, by using the pressure accumulator 10, there is an advantage that a stable pressure can be maintained regardless of the operating state. The fuel in the pressure accumulator 10 is supplied to the pressure booster 20 through the fuel passages 61 and 62 branched from the fuel passage 6, and is supplied from the fuel passage 62 to the injection nozzle 30 through the fuel passage 63.

  The intensifier 20 has a large-diameter piston 21 that can slide while maintaining oil-tightness inside the large-diameter bore 2a, and a small-diameter plunger 22 that can slide while maintaining oil-tightness inside the small-diameter bore 2b. The large-diameter piston 21 and the small-diameter plunger 22 are provided so as to slide in the vertical direction substantially in unison with their axes aligned, and function as a pressure-increasing piston. A space surrounded by the upper end surface of the large-diameter piston 21 (the end surface opposite to the small-diameter plunger 22) and the upper-end inner peripheral surface of the large-diameter bore 2a is a drive chamber 23. High pressure fuel is introduced into the drive chamber 23 from the fuel passage 61 so that downward hydraulic pressure acts on the pressure increasing piston.

  On the other hand, a space surrounded by the lower end surface of the small diameter plunger 22 (the end surface opposite to the large diameter piston 21) and the lower end inner peripheral surface of the small diameter bore 2b is a high pressure chamber 24. The high-pressure chamber 24 communicates with the fuel reservoir 36 of the injection nozzle 30 through the fuel passage 63, and communicates with the fuel passage 62 through the check valve 40 and through the fuel passage 64 having the throttle 52. It communicates with the back pressure chamber 34. The check valve 40 allows only the fuel flow in the direction of the high pressure chamber 24 and the injection nozzle 30, and includes, for example, a ball-shaped valve element disposed in a large diameter portion provided in the middle of the fuel passage 62. . The valve body is normally urged in the valve closing direction (upward) by a return spring, but the illustration is omitted here.

  A control chamber 25 is formed by the lower end surface of the large diameter piston 21 (the end surface on the small diameter plunger 22 side), the lower end inner peripheral surface of the large diameter bore 2a, and the upper end outer peripheral surface of the small diameter plunger 22. The control chamber 25 is provided with a return spring 26 that urges the large-diameter piston 21 upward. The pressure in the control chamber 25 is controlled by the control valve 100 communicating with the fuel passage 72 having the throttle 54, and the pressure-increasing piston (the large diameter piston 21 and the small diameter plunger 22) slides in the bore. Thus, the fuel in the high pressure chamber 24 can be increased.

  The injection nozzle 30 slides in the vertical direction in the figure while maintaining oil tightness in a bore 32 provided in the fourth body B4, and applies a back pressure to the needle valve 31 to open and close the injection hole 35. A back pressure chamber 34 is provided. The back pressure chamber 34 is formed by the upper end surface of the needle valve 31 and the inner peripheral surface of the upper end of the bore 32, and a spring 33 that urges the needle valve 31 in the valve closing direction is disposed in the back pressure chamber 34. . The injected fuel is supplied from the fuel passage 63 to the nozzle hole 35 through the fuel reservoir 36 provided around the intermediate portion of the needle valve 31.

  The control valve 100 has two control functions, and the valve body 101, which is a movable member, slides in the up-down direction in the figure while maintaining oil tightness in the bore provided in the first body B1, thereby increasing the pressure intensifier 20. The pressure boosting piston drive and the injection from the injection nozzle 30 are controlled. A disc-shaped armature 132 is coupled to the upper end of the valve body 101 and operates as a two-position electromagnetic actuator 130 in cooperation with the electromagnetic coil 131 and the return spring 133. The armature 132, the electromagnetic coil 131, and the return spring 133 are accommodated in the second body B2.

  The valve body 101 is a spool valve structure having a cylindrical seal portion, and has two small diameter portions 102 and 103 in the axial direction (operation direction). The two small-diameter portions 102 and 103 are arranged at a sufficient interval in the vertical direction in the figure, and a plurality of annular grooves 112 and 111 and annular grooves 121 and 122 are formed on the inner peripheral surfaces of the opposing bores, respectively. They are provided in this order in the vertical direction. The small diameter portions 102 and 103, the annular grooves 111 and 112, and the annular grooves 121 and 122 constitute control function portions, respectively, and perform opening / closing control of the flow path according to the positions of the small diameter portions 102 and 103. . That is, the upper narrow diameter portion 102 and the annular grooves 111 and 112 constitute a pressure increase control valve portion 110 that opens and closes as a two-position two-way valve, while the lower narrow diameter portion 103 and the annular groove 121, 122 comprises the injection control valve part 120 which opens and closes as a 2 position 2 way valve.

  In the pressure increase control valve portion 110, the annular groove 111 communicates with the fuel tank T via the fuel return passage 7, and the annular groove 112 communicates with the control chamber 25 of the pressure booster 20 via the throttle 54 and the fuel return passage 72. ing. Therefore, by switching the position of the valve body 101 with the actuator 130, the annular groove 111 and the annular groove 112 communicate with each other through the gap around the small diameter portion 102, or the communication is blocked. With this opening / closing operation, the pressure in the control chamber 25 can be increased or decreased to control the drive of the hydraulic piston of the pressure intensifier 20.

  In the injection control valve unit 120, the annular groove 121 communicates with the back pressure chamber 34 of the injection nozzle 30 via the throttle 53 and the fuel return passage 71, and the annular groove 122 communicates with the fuel tank T via the fuel return passage 7. ing. Then, by switching the position of the valve body 101 with the actuator 130, the annular groove 121 and the annular groove 122 communicate with each other through the gap around the small diameter portion 103, or the communication is blocked. With this opening / closing operation, the pressure in the back pressure chamber 34 can be increased or decreased to control the driving of the needle valve 31.

  Here, the valve body 101 has the same diameter in the vertical direction and the lower end of the valve body 101 via the annular groove 122, with the diameters of the sliding portions of the narrow diameter portions 102 and 103 being constant, and the area receiving the hydraulic pressure. It is arranged in a low pressure chamber at the lower end of the bore communicating with the fuel return passage 7. Thereby, the axial pressure applied to the valve body 101 is canceled, and the pressure is always balanced regardless of the state of operation. Thereby, the required suction | attraction force of the actuator 130 of the control valve 100 can be reduced, and it can comprise in a small size.

  The constitutional feature of the present invention is that the control valve 100 as a two-position valve driven by the two-position actuator 130 is provided with two control valve portions 110 and 120, and these two control valve portions 110, This is because there is a deviation in operation between 120. Specifically, the operation control timing of the pressure increase control valve unit 110 and the injection control valve unit 120 is shifted so that the pressure increase operation control start of the pressure increase control valve unit 110 is early and the control end is delayed, that is, When the injection is started from the injection stop state, the injection control valve unit 120 operates after the operation of the pressure increase control valve unit 110, and when the injection is stopped, the operation is delayed after the operation of the injection control valve unit 120. The pressure increase control valve unit 110 is configured to operate to suppress a decrease in the injection pressure. In the present embodiment, as shown in FIG. 2, when the operating lift position of the pressure increase control valve section 110 is ha and the operating lift position of the injection control valve section 120 is hi, the valve body is such that hi> ha. 101, and there is a shift in operation of X = hi-ha.

  The operation of the fuel injection device having the above configuration will be described with reference to FIGS. FIG. 2 shows a state in which the valve body 101 of the control valve 100 is at the initial position (upper end position) by the return spring 133 (FIG. 5). In this state, in the pressure increase control valve portion 110, the cylindrical seal surface 104 following the lower end of the small diameter portion 102 blocks communication between the annular groove 111 and the annular groove 112, and is in a closed state. At this time, in the pressure intensifier 20, the pressure in the control chamber 25 communicating with the annular groove 112 is increased by the pressure from the pressure accumulator 10 communicating through the fuel passage 62 and the throttle 51, and this same pressure is the fuel pressure. Since the high pressure chamber 24 is also supplied to the high pressure chamber 24 through the drive chamber 23 and the fuel passage 62 through the passage 61, the force received from the upper and lower chambers 23, 24, 25 of the pressure intensifier 20 is balanced. . At this time, the large-diameter piston 21 and the small-diameter plunger 22 are moved upward in the drawing by the return spring 26 (FIG. 5), and the high-pressure chamber 24 is filled with fuel through the fuel passage 62 and the check valve 40.

  In this initial state, the injection control valve portion 120 is in a closed state because the cylindrical seal surface 105 following the lower end of the small diameter portion 103 blocks communication between the annular groove 121 and the annular groove 122. At this time, the pressure of the back pressure chamber 34 of the injection nozzle 30 becomes the same as the pressure of the high pressure chamber 24 communicating with the throttle 52 and the fuel passage 64, that is, the same pressure as the accumulator 10, and the needle valve 31 (FIG. 5) The sum of the oil pressure acting downward and the spring force is greater than the oil pressure upward. Therefore, the injection nozzle 30 is not opened and no injection is performed.

  Next, when the electromagnetic coil 131 of the actuator 130 is energized, a suction force is generated, and the valve body 101 of the control valve 100 starts to move downward in the drawing. FIG. 3 shows a moving state. In the pressure increase control valve unit 110, the cylindrical seal surface 104 is lowered to a position where the annular groove 111 and the annular groove 112 are communicated with each other, and is in an open state. Accordingly, the control chamber 25 of the intensifier 20 communicates with the fuel return passage 7 via the throttle 54, the fuel return passage 72, the annular groove 112, and the annular groove 111. As a result, the pressure in the control chamber 25 is released, the balance of the force received by the large-diameter piston 21 of the intensifier 20 from the upper and lower chambers 23, 24, and 25 is lost, and the large-diameter piston 21 and the small-diameter plunger 22 move downward. Begin.

  Due to the lift of the pressure increasing piston, the pressure in the high pressure chamber 24 starts to increase. Finally, when the cross-sectional area ratio of the large-diameter piston 21 and the small-diameter plunger 22 is increased, for example, when the pressure of the accumulator 10 is 50 MPa and the cross-sectional area ratio is set to 4, the pressure in the high-pressure chamber 24 is 4 times. The pressure is increased to 200 MPa. In this state, since the injection control valve unit 120 is still closed, the injection nozzle 30 is not opened and injection is not performed. Since the actuator 130 has two positions, this state is not stable and shows a transient state.

  FIG. 4 shows a state where the valve body 101 further moves and is displaced to the lower end position. In this state, the communication state of the pressure increase control valve unit 110 remains as shown in FIG. 3, and the injection control valve unit 120 is in an open state in which the annular groove 121 and the annular groove 122 communicate with each other. Accordingly, since the back pressure chamber 34 of the injection nozzle 30 communicates with the fuel return passage 7 via the throttle 53, the fuel return passage 71, the annular groove 121, and the annular groove 122, the nozzle back pressure is released.

  Here, the pressure in the back pressure chamber 34 immediately before being opened is the same high pressure as that of the high pressure chamber 24 that communicates, and the fuel reservoir 36 that acts upward on the needle valve 31 also has the same high pressure. Since the upward force is reduced by the inner part of the seat diameter, the valve closing remains maintained. When the back pressure is released, the upward oil pressure overcomes the downward force of the spring 33 (FIG. 5), and the injection nozzle 30 opens. Then, the fuel whose pressure has been increased in the high pressure chamber 24 is injected from the injection hole 35 (FIG. 5) through the fuel passage 63 and the fuel reservoir 36.

  By continuing this state and proceeding with the pressure-increasing operation by lifting the pressure-increasing piston, main injection at an ultrahigh pressure becomes possible. At the time of the minute injection, the state of FIG. 4 is immediately returned to the state of FIG. 2, so that the injection can be performed before the pressure increase proceeds, that is, at a lower pressure. To end the injection, the control valve 100 is returned to the initial position by stopping energization of the actuator 130, and the state shown in FIG. 2 is obtained.

  FIG. 6 is a timing chart showing the above operation. In the figure, the timing of a) corresponds to the initial state of FIG. 2, the timing of b) corresponds to the transient state of FIG. 3, and the timing of c) corresponds to the injection state of FIG. When the drive signal is output to the actuator 130 and the valve body 101 starts to move, first, the pressure increasing port (annular groove 112-annular groove 111) of the pressure increasing control valve unit 110 shifts from the closed state to the open state. As the pressure in the control chamber 25 is released due to the opening of the pressure-increasing port, the pressure-intensifying piston of the pressure intensifier 20 starts to lift, and the fuel in the high-pressure chamber 24 is increased in pressure. Furthermore, when the valve body 101 moves, injection is started from the injection nozzle 30 at the same time as the injection port (annular groove 121-annular groove 122) shifts from the closed state to the open state. The reverse is true when injection stops.

  What should be noted in the present invention is that the injection start timing e) of the injection control valve section 120 is delayed from the pressure increase start timing d) of the pressure increase control valve section 110 (A in the figure). This is that the pressure increase end timing g) of the pressure control valve section 110 is delayed from the injection end timing f) of the injection control valve section 120 (B in the figure). This is due to the operation deviation X = hi-ha provided between the two control valve portions 110 and 120 in the configuration of the valve body 101 described above. In the present invention, by providing this operation deviation, the volume of each chamber 23, 24, 25 of the pressure intensifier 20 and the movement stroke of the pressure increasing piston are changed according to the volume of each chamber 34, 36 of the injection nozzle 30 and the needle valve. It is possible to suppress the system operation delay due to being larger than 31 lift.

  Accordingly, the pressure booster 20 does not inject the fuel without sufficiently increasing the pressure, and the injection at an ultrahigh pressure is possible with a simple configuration. Here, FIG. 6 is an example, and the drive signal to the actuator 130 and the displacement X of the operation can be appropriately changed. Therefore, the injection control is started or ended at the desired timing of pressure increase, and according to the operation state. Optimal injection characteristics can be obtained.

  In the injection that does not require ultra-high pressure, such as micro injection, the time that the injection control valve unit 120 is in the injection state is extremely short, and the pressure increase operation time of the pressure increase control valve unit 110 associated therewith is also short. It is possible to perform injection at a relatively low pressure before the pressurization proceeds by using. Furthermore, since the pressure increasing period is longer than the injection period, so-called after injection, in which minute injection is performed at an ultrahigh pressure immediately after main injection, is also possible. Further, it is possible to prevent a pressure drop at the end of injection, which has been a problem in the past.

  As described above, the present invention uses only one control valve 100 having a simple configuration in which one two-position electromagnetic actuator 130 and one valve body 101 are combined. A control function can be provided. Further, by providing a deviation in operation between these two control function units, it is possible to perform injection without loss due to the injection pressure increased and pressurized over the entire injection period, and the main injection, the low pressure or the ultrahigh pressure in the ultrahigh pressure injection Various injection patterns such as micro injection can be realized. The control valve 100 has a simple configuration in which the valve body 101 is pressure-balanced and a deviation is set between the control edges of the two control units. The actuator 130 is a low-cost electromagnetic type and a two-position type valve body. 101 and good control compatibility. Therefore, a high-performance fuel injection device excellent in economy and controllability has been obtained.

  A second embodiment of the present invention will be described with reference to FIGS. The basic configuration and operation of the fuel injection device of the present embodiment are the same as those of the first embodiment, and the configuration of the control valve 100 is different. Hereinafter, this difference will be mainly described. As shown in FIGS. 7 and 8, in this embodiment, the valve body 101 of the control valve 100 is divided into two parts, the pressure increase control valve part 110 side and the injection control valve part 120 side, and pressure increase control as the first valve body is performed. The valve body 101a performs pressure increase operation control, and the injection control valve body 101b as the second valve body performs injection operation control. In the first embodiment, the valve body 101 has a cylindrical seal structure. However, in this embodiment, the seat portions of the increase control valve body 101a and the injection control valve body 101b are formed as cone sheets (conical sheet) 106, 107. Yes. Alternatively, a flat sheet can be used instead of the cone sheet.

  In FIG. 7, the pressure increase control valve body 101 a has a conical portion whose diameter is reduced upward with a lower end portion located in the annular groove 111, and an outer peripheral surface thereof is a cone seat 106. The intermediate part continuing above the conical part is a small diameter part. The armature 132 of the actuator 130 is coupled to the upper end of the pressure increase control valve body 101a. An annular groove communicating with the control chamber 25 of the pressure booster 20 through the fuel return passage 72 and the throttle 54 is seated on the cone seat 106 of the pressure increase control valve body 101a at the upper end position shown in the figure when not energized. The communication between 112 and the annular groove 111 communicating with the fuel return passage 7 is closed. At this time, the high pressure fuel from the pressure accumulator 10 is supplied to the control chamber 25 of the pressure booster 20 communicating with the annular groove 112.

  The injection control valve body 101b has an intermediate portion as a small diameter portion, a lower end portion located in the annular groove 122 as a conical portion whose diameter is reduced upward, and an outer peripheral surface thereof as a cone seat 107. In the state of FIG. 7, the cone seat 107 of the injection control valve body 101 b is also seated, and communication between the annular groove 121 that communicates with the back pressure chamber 34 of the injection nozzle 30 and the annular groove 122 that communicates with the fuel return passage 7. Is closed. At this position, a gap hg is provided between the two control valve bodies 101a and 101b. Further, as shown in FIG. 8, the injection control valve body 101b is urged in the seating direction by a return spring 205 disposed below.

  Next, when the electromagnetic coil 131 of the actuator 130 is energized, a suction force is generated, and the pressure increase control valve body 101a starts moving downward. When the annular groove 111 communicating with the fuel return passage 7 is opened due to the lift of the pressure increase control valve body 101a, the pressure increase operation state is established, and after the lift and the hg lift point (lift amount = hg) are passed, Is lifted together with the injection control valve body 101b to be in an injection operation state. In the present embodiment, the operation of the injection control unit 120 is delayed by this gap hg, and has the same role as the operation deviation X = hi-ha in the first embodiment. Other configurations and operations are the same as those in the first embodiment, and the same effects can be obtained.

  In the second embodiment as well, the actuator 130 has two positions. That is, the position of the lift hg is not stable and is a passing point. The lift hs of the actuator 130 is determined by the injection control valve body 101b coming into contact with the bottom surface of the annular groove 122, and naturally has a relationship of hs> hg. Also in the present embodiment, the pressure increase control valve element 101a is a two-position two-way valve, and the injection control valve element 101b is a two-position two-way valve.

  The feature of the present embodiment is that the pressure increase control valve body 101a and the injection control valve body 101b are separately provided, so that the operation deviation X can be easily set by the gap hg. That is, the seat position is adjusted by adjusting the length of the annular groove seated by the valve body without changing the structure of the valve bodies 101a and 101b, or the distance between the seating seat position and the contact end surface is adjusted or controlled. A desired characteristic can be realized by adjusting the gap to be a predetermined gap by a simple method such as disposing a shim between the valve portions 110 and 120. In addition, in the cylindrical seal structure as in the first embodiment, there is a gap on the outer periphery, but by using a cone sheet 106, 107 or a flat sheet, there is no gap like the cylindrical seal, and the sheet surface pressure is reduced. Since it is raised, the sealing performance is improved. Further, the axial seal length required for the cylindrical seal is not required, and the total lift amount of the actuator 130 can be reduced, so that the responsiveness is improved and the configuration of the actuator 130 can be reduced in size.

It is a mimetic diagram showing a schematic structure of a fuel injection device of an internal-combustion engine of the present invention. It is a schematic block diagram (initial state) of the fuel-injection apparatus which shows the 1st Embodiment of this invention. It is a schematic block diagram (transient state) of the fuel-injection apparatus for demonstrating the action | operation of 1st Embodiment. It is a schematic block diagram (injection state) of the fuel-injection apparatus for demonstrating the action | operation of 1st Embodiment. It is sectional drawing which shows the whole structure of the fuel-injection apparatus of 1st Embodiment. It is a time chart for demonstrating the action | operation of 1st Embodiment. It is a schematic block diagram (initial state) of the fuel-injection apparatus which shows the 2nd Embodiment of this invention. It is sectional drawing which shows the whole structure of the fuel-injection apparatus of 2nd Embodiment.

Explanation of symbols

T Fuel tank 10 Pressure accumulator 20 Pressure booster 21 Large diameter piston (pressure boosting piston)
22 Small-diameter plunger (pressure-increasing piston)
Reference Signs List 23 Drive chamber 24 High pressure chamber 25 Control chamber 30 Injection nozzle 31 Needle valve 34 Back pressure chamber 35 Injection hole 36 Fuel reservoir 40 Check valve 51-54 Restriction 6, 61-64 Fuel passage 7, 71, 72 Fuel return passage 100 Control valve 101 Valve body 101a First valve body 101b Second valve body 102, 103 Small diameter portion 110 Pressure increase control valve portion (control function portion)
111, 112 annular groove 120 injection control valve part (control function part)
121, 122 Annular groove 130 Electromagnetic actuator 131 Electromagnetic coil 132 Armature

Claims (9)

An accumulator for accumulating fuel;
A pressure intensifier for increasing the pressure of the fuel supplied from the pressure accumulator to the high pressure chamber by driving the pressure increasing piston;
In a fuel injection device for an internal combustion engine comprising an injection nozzle that is controlled to open and close by increasing or decreasing the hydraulic pressure of a back pressure chamber and injects fuel directly supplied from the pressure accumulator or fuel increased in pressure by the pressure intensifier,
Driven by one two-position electromagnetic actuator to perform two control functions, one of the two control function units controls the pressure increasing operation of the pressure intensifier, and the other controls the injection operation of the injection nozzle. While providing a control valve which is an injection control valve part to control,
Both of the control valves function as two-position two-way valves, and the start of the pressure increase operation control by the pressure increase control valve portion is earlier than the start of the injection operation control by the injection control valve portion. The operation of the two control function units is deviated so that the end of the pressure increase operation control by the pressure increase control valve unit is later than the end of the injection operation control by the injection control valve unit. A fuel injection device for an internal combustion engine.   The fuel injection device for an internal combustion engine according to claim 1, wherein the control valve always balances the pressure in the operation direction.   The fuel injection device for an internal combustion engine according to claim 1 or 2, wherein the movable member of the control valve comprises a single valve body directly connected to the electromagnetic actuator.   The fuel injection device for an internal combustion engine according to claim 3, wherein the movable member of the control valve has a spool valve shape having a cylindrical seal portion.   The control edge of the cylindrical seal portion of the movable member enters the pressure increasing operation control state prior to the injection operation control according to the lift of the movable member, and the pressure increasing operation control ends after the injection operation control according to the return lift. The fuel injection device for an internal combustion engine according to claim 4, wherein the fuel injection device is arranged to be in a state.   The movable member of the control valve is composed of two valve bodies, one of which is a first valve body that controls the pressure-increasing operation of the pressure-increasing control valve section, and the other is a first valve body that controls the injection operation of the injection control valve section. The first valve body is directly connected to the electromagnetic actuator, and the second valve body is driven by the driving force of the electromagnetic actuator via the first valve body. The fuel injection device for an internal combustion engine according to claim 1 or 2.   The fuel injection device for an internal combustion engine according to claim 6, wherein the movable member of the control valve has a cone seat or a flat seat.   The two valve bodies of the control valve are arranged on the same axis, the two valve bodies are seated together, and the operation is performed between the two valve bodies in the initial state in which the pressure increasing operation is stopped and the injection operation is stopped, respectively. The fuel injection device for an internal combustion engine according to claim 7, wherein a gap corresponding to the deviation is provided. The clearance between the two valve bodies of the control valve is set by adjusting a seat position of at least one valve body, or adjusting a distance between contact end surfaces from the seat, or by adjusting a shim. Item 9. A fuel injection device for an internal combustion engine according to Item 8.

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