WO2003008795A1 - Accumulating fuel injector - Google Patents

Abstract

An accumulating fuel injector capable of suppressing a variation in oil amount injected from injectors by reducing a pressure pulsation in return tubes connected to the injectors, wherein, in an accumulating fuel feed device having a plurality of injectors (4) for injecting the high-pressure fuel accumulated in a common rail (3) into the cylinders of an internal combustion engine, controlling the injection from the injectors (4) by controlling pressures in the back pressure control chambers thereof, and returning the fuel oil leaked from the back pressure control chambers to a fuel tank (1) through a return tube (8) connected to the injectors (4), an orifice (56) restricting a passage area is installed in the return tube (8) on the downstream side of a portion where the fuel oil leaked from the plurality of injectors (4) is merged, and the orifice may be installed between the injectors in the return tube, the injectors with different injection timings may be connected to the different tubes, and the return tube may be formed of a soft tube.

Description

 Description Accumulated fuel injection system Technical field

 According to the present invention, high-pressure fuel supplied from a fuel supply pump is temporarily stored in a common rail, and the high-pressure fuel stored in the common rail is supplied to each cylinder from a plurality of injectors provided for each cylinder of the internal combustion engine. And a pressure accumulating fuel injection device. Background art

 Conventionally, various types of injectors have been known as injectors used in this type of fuel injection device. For example, Japanese Patent Application Laid-Open No. H11-210589 discloses a type of injector. A valve body (nozzle needle) that opens and closes the injection hole formed in the injector body, and a back pressure control chamber into which fuel from the common rail is introduced to apply an operating force to the valve body in the direction to close the injection hole (Back pressure chamber), an oil sump (oil sump) into which fuel from the common rail is introduced to apply an operating force to the nozzle needle in the direction of opening the injection hole, and a fuel oil in the back pressure control chamber. It comprises an on-off valve (valve) for leaking, and an actuator (electromagnetic coil, spring for biasing the valve in the valve closing direction, etc.) for controlling the on-off operation by the on-off valve. The fuel leaked from the back pressure control chamber of each injector is led to the fuel tank via a common return pipe connected to the injector.

However, in the accumulator type fuel supply device provided with the above-described type of injector, the movable part such as the armature of the actuator is a return pipe. The movable part is lifted by electromagnetic force when the actuator is energized, and the on / off valve is opened and closed by returning the movable part by the reaction force of the spring by releasing the energization. Therefore, if the pressure pulsation caused by the leak of fuel oil in the back pressure control chamber continues in the return pipe, the pressure acting on the movable part of the actuator also fluctuates. As a result, there is a disadvantage that the dynamic characteristic of the on-off valve changes due to the pressure pulsation and the injection amount of the injector changes. That is, the injector is adjusted so as to obtain a predetermined injection amount assuming a stable movement of the movable portion of the actuator, but when the next injection is performed in a state where the pressure pulsation in the return pipe is large. However, when the injection timing of the injector coincides with the point in time when the pressure in the return pipe falls and the injection timing of the injector also coincides, the pressure acting on the movable part of the actuator also decreases, so that the lift speed of the movable part increases and the back pressure control chamber There is the disadvantage that fuel oil leaks rapidly and the valve body lifts immediately, increasing the injection volume.

Such inconvenience occurs when the pressure in the return pipe continues to pulsate greatly even when the distance between the injectors connected to the return pipe is long. It has been confirmed that the injection quantity increases sharply when the point of time when the pressure falls below atmospheric pressure coincides with the injection timing of the injector. It is also known that such a change in the injection amount becomes larger as the engine rotation speed becomes higher at a small injection amount such as a pilot injection, and when the pressure pulsation in the return pipe becomes larger, the injection amount becomes larger. There is an inconvenience that bitation is likely to occur and erosion of the actuator chamber around the ball seat portion is promoted and the life of the component parts is shortened. Disclosure of the invention Therefore, in the present invention, the pressure pulsation of the return pipe connected to the injector is reduced, and the influence of the injector on the actuator is reduced, thereby suppressing the variation in the amount of oil injected from each injector regardless of the injection timing. The main object is to provide a pressure-accumulation type fuel injection device that can perform the operation. It also aims to prevent cavitation in the return pipe and reduce erosion in the actuator room around the pole seat.

 In order to achieve the above object, a pressure-accumulation fuel supply device according to the present invention includes a common rail for accumulating high-pressure fuel pumped from a fuel supply pump, and injecting the high-pressure fuel accumulated on the common rail into a cylinder of a high-pressure engine A plurality of injectors, each of which is provided with a valve body for opening and closing an injection hole, and a fuel oil from the common rail for applying an operating force to the valve body in a direction to close the blind hole. A back-pressure control chamber to be introduced; an on-off valve for releasing the operating force of the valve body in the closing direction by leaking fuel oil in the back-pressure control chamber; and an actuator for controlling the on-off operation by the on-off valve. Wherein the fuel oil leaked from the back pressure control chamber is returned to a low pressure source via a return pipe connected to the injector. In the return pipe, a throttle means for reducing the passage area is provided at a portion downstream of a portion where the fuel oil leaking from the plurality of injectors joins.

 Therefore, a throttle means is provided on a path on which fuel leaking from a plurality of injectors connected to the return pipe is collected and returned to the low-pressure source, so that pressure fluctuations in the return pipe are absorbed and the pressure in the return pipe is reduced to the atmospheric pressure. Thus, the pressure pulsation acting on the actuator of the injector can be reduced.

Also, assuming such a configuration, the return pipe is It may be constituted by a common pipe to be connected, and further provided with a throttle means for narrowing the passage area between the respective injectors.

 According to such a configuration, it is possible to keep the pressure in the return pipe at or above the atmospheric pressure and to make it difficult to transmit the pressure pulsation generated in the part of the return pipe connected to the adjacent injector to another injector. And the pressure pulsation can be terminated quickly.

 Furthermore, assuming the basic configuration described above, the return pipe is composed of a plurality of branch pipes for connecting injectors and a collecting pipe to which these branch pipes are connected, and different injectors with different injection timings are used. May be connected to different branches.

 According to such a configuration, since the branch pipe to which the injector injected previously and the branch pipe to which the next injector is connected are different, the pressure pulsation generated in each branch pipe is different. It becomes difficult to be transmitted to the branch pipe of the second injector, so that it is less likely to be affected by the pressure pulsation generated during the previous injection when the next injector is injected. '' Furthermore, on the premise of the basic configuration described above, the return pipe may be made of a soft tube that can be elastically deformed by the pressure of fuel oil leaking from the back pressure control chamber of the injector. Good.

 According to such a configuration, the pressure pulsation generated at the time of the injection of each injector can be absorbed by the soft tube constituting the return pipe, and the pressure pulsation can be quickly terminated. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration example of a pressure accumulating fuel supply device according to the present invention. FIG. 2 is a cross-sectional view showing an injector used in the accumulator-type fuel supply device of FIG. FIG. 3 is an enlarged sectional view showing a main part of the injector shown in FIG. FIG. 4 is a diagram showing pressure changes in the return pipe detected by the pressure sensors A and B in the accumulator type fuel supply device shown in FIG. 1. FIG. Fig. 4 (b) shows the measurement results when the engine speed was set to 200 rpm, and Fig. 4 (c) shows the measurement results when the engine speed was set to 200 rpm. The results of the measurement in the case where the rotation was set at +400 revolutions per minute are shown.

 FIG. 5 is a diagram showing another configuration example of the accumulator type fuel supply device according to the present invention.

 FIG. 6 is a diagram showing a change in the pressure of the return pipe detected by the pressure sensors A and B in the accumulator type fuel supply device shown in FIG. 5, and FIG. Fig. 6 (b) shows the measurement results when the engine rotation speed was set to 200 rpm, and Fig. 6 (c) shows the measurement results when the engine rotation speed was set to 200 rotations per minute. The measurement results when the rotation speed is set to 400 000 revolutions per minute are shown.

 FIG. 7 is a diagram showing still another configuration example of the accumulator-type fuel supply device according to the present invention.

 FIG. 8 is a diagram showing a change in the pressure in the return pipe detected by the pressure sensors A and B in the accumulator type fuel supply device shown in FIG. 7, and FIG. Fig. 8 (b) shows the measurement results when the engine rotation speed was set to 200 rpm, and Fig. 8 (c) shows the measurement results when the engine rotation speed was set to 200 rotations per minute. The measurement results when the rotation speed is set to 400 000 revolutions per minute are shown.

FIG. 9 is a diagram showing a pressure change in the return pipe detected by the pressure sensors A and B when the return pipe is configured by a soft tube in the accumulator type fuel supply device shown in FIG. Fig. 10 shows the case where the injection timing is shifted between the accumulator type fuel supply device shown in Fig. 1, Fig. 5, and Fig. 7 and the accumulator type fuel supply device in which the return pipe is composed of a soft tube in the configuration of Fig. 1. FIG. 8 is a view showing an experimental result of measuring a change in pressure of the return pipe at the start of injection.

 Fig. 11 shows a conventional accumulator fuel supply device, the accumulator fuel supply device shown in Figs. 1 and 5, and the accumulator fuel in which the return pipe in the configuration of Fig. 1 is constituted by a soft tube. FIG. 9 is a diagram showing experimental results obtained by measuring a change in the pilot injection amount when the injection timing is shifted in the supply device. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, an embodiment of an accumulator-type fuel supply device according to the present invention will be described with reference to the drawings. In FIG. 1, a pressure-accumulating fuel supply device includes a fuel tank 1 constituting a low-pressure source, a fuel supply pump 2 for supplying fuel under pressure, and a common rail 3 for storing high-pressure fuel supplied from the fuel supply pump. The engine includes an injector 4 provided for each cylinder of the internal combustion engine.

 This accumulator type fuel supply device connects a fuel tank 1 and a fuel supply pump 2 with a pipe 5, a fuel supply pump 2 with a common rail 3, a pipe 6, and connects the common rail 3 with each injector 4. The fuel oil pumped up from the fuel tank 1 is pressurized by the fuel supply pump 2 and then pressure-fed to the common tray 3 to supply fuel to each injector 4 from the common nozzle 3. I have. The accumulator type fuel supply device returns fuel oil having a predetermined pressure or more sent to the fuel supply pump 2 through the return pipe 8 to the fuel tank 1 and also has a fuel oil injector having a specified pressure or more in the common rail 3. The fuel oil leaking during the injection of 4 and the fuel leaking from the sliding parts are returned to the fuel tank 1.

2 and 3, the specific configuration of the injector 4 is shown. ―

03/008795

The injector 4 is provided with a nozzle body 12 in which an injection hole 11 is formed at the tip of the injector housing 10, and a retaining nut 13 is screwed around the injector housing 10 to form an injector. The housing 10 and the nozzle body 12 are integrally fastened. A fuel inlet 14 is formed on the upper side surface of the injector housing 10. The fuel inlet 14 is provided with a passage 15 formed in the injector housing 10 and a passage 16 formed in the nozzle body 12. Through the oil reservoir 17 formed in the middle of the nozzle body 12. A pressure receiving portion 20 of a nozzle needle 19 slidably inserted into a fitting hole 18 of the nozzle body 12 faces the oil reservoir 17. The high-pressure fuel flowing from the fuel inlet 14 into the pressure receiving section 20 always flows.

 On the axis of the injector housing 1 ◦, there is formed a through-hole 21 which is aligned with the fitting hole 18 of the nozzle body 12, and in this through-hole 21, a nozzle hole 19 and a pozzolet 22 are provided. A nozzle piston 23 is disposed, which is displaceable integrally with Nozno Renee Donore 19. A nozzle spring 25 is elastically mounted between the spring receiver 24 provided on the injector housing 10 and the port 22 with a predetermined set force. Is always urged in the direction of closing the borehole 11.

A valve body 26 into which nozzle nozzles 23 are slidably inserted is inserted into a through hole 21 in the upper part of the housing 10 so that the valve body 1 26 and the nozzle piston 2 3 A back pressure control room 27 is formed by the space surrounded by. An annular space 28 communicating with the passage 15 is formed around the valve body 26, and the annular space 28 is connected to the back pressure via a first throttle passage 31 formed in the valve body 26. Control room 2 7 I am trying to communicate with Here, the effective pressure receiving area of the valve piston 23 facing the back pressure control chamber 27 (the area projected on the surface perpendicular to the axis of the valve piston 23) is the nozzle facing the oil reservoir 17 It is formed larger than the effective pressure receiving area of the needle (area projected on a plane perpendicular to the axis of the nozzle needle).

 A core holder 35 holding a core 34 on which the exciting coil 33 is wound is fixed to the injector housing 10 by a retaining nut 36 on the upper part of the inductor housing 10. An actuator chamber 37 is formed by a space surrounded by the core 34, the core holder 35, and the injector housing 10.

 In the upper part of the valve body 26, there is provided a second throttle passage 32 that communicates the back pressure control chamber 27 and the actuator chamber 37, and the second throttle passage 32 is a valve that constitutes an on-off valve. It can be opened and closed by poles 38. A bowl-shaped pole seat portion S9 that expands upward is formed at the peripheral edge of the valve body 26 where the second throttle passage 32 opens, and the movement of the valve ball 38 from above. It is regulated by the anchor port 40 that abuts.

 In the actuator chamber 37, an anchor guide 41 for slidably holding an anchor bolt 40 is provided at an upper portion of the pulp pod 26 via a spacer 42, and at an upper portion of the anchor port 40. An anchor plate 43 that is attracted to the core 34 by energizing the exciting coil 33 facing the core 34 is fixed. The anchor plate 43 is urged toward the core by an anchor spring 44 provided between the anchor plate 43 and the anchor guide 41.

The upper part of the anchor bolt 40 is inserted into a through hole 45 formed at the center of the core 34 via the anchor plate 43, and A core valve spring 47 mounted between the back flow tube 46 attached to the upper portion constantly urges the anchor bonoleto 40 toward the valve body 26. The core valve spring 47 has a stronger spring force than the anchor spring 44, and when the excitation coil 33 is not energized, the anchor bolt 40 is displaced downward so that the anchor bolt 40 is displaced downward. The plate 43 is separated from the core 34 and the valve ball 38 is pressed against the pole seat portion 39 to close the second throttle passage 32.

 The knock flow tube 46 has a fuel discharge port 48 formed so as to be aligned with the through hole 45 of the core 34. The fuel discharge port 48 is connected to the actuator chamber 37 and a passage (not shown). The fuel is always communicated through the fuel tank 37 and the fuel leaked to the actuator chamber 37 is discharged through the fuel discharge port 48.

 Reference numeral 50 denotes a connector for supplying a current to the exciting coil 33, and reference numeral 51 denotes a leak passage for guiding fuel leaking through the clearance to the actuator chamber 37. The current supplied to the exciting coil 33 of the injector 4 is controlled by an electronic control unit (ECU) based on various information signals such as the engine speed detected by various sensors (not shown). It has become.

Therefore, when the excitation coil 33 is not energized, the anchor plate 4 3 is pressed downward by the core valve spring 47, and the valve pole 38 is pressed against the pole seat portion 39 to form the second throttle passage. 3 2 is closed. For this reason, the back pressure control chamber 27 is filled with high-pressure fuel from the common rail 3 via the first orifice 31, and the fuel oil pressure in the back pressure control chamber 27 is maintained. On the back of the valve piston 23. Also common to oil sump 17 Since high-pressure fuel is guided from the rail 3, the fuel oil pressure is applied to the nozzle needle 19 in the valve opening direction, but the nozzle needle 19 has a difference in effective pressure receiving area with the valve piston 23. , And the nozzle spring 25 is pressed downward by the set force of the nozzle spring 25, and the injection hole 11 is closed.

 In this state, when the excitation coil 33 is energized, the electromagnetic plate attracts the anchor plate 43 to the core 34, and the valve pawn 38 separates from the ball seat portion 39, and the second throttle passage 3 2 will be released. Then, the high-pressure fuel oil in the back pressure control chamber 27 flows out to the actuator chamber 37 via the second throttle passage 32, and the back pressure of the valve piston 23 decreases, and the oil flows into the oil sump chamber 17. Due to the pressure of the filled fuel oil, the nozzle needle nozzle 19 overcomes the set force of the valve piston 23 and the nozzle swung 25 and is pushed upward, and the injection hole 11 is opened to start the fuel injection. It will be.

 Then, when the energization to the exciting coil 33 is stopped, the anchor plate 43 is pushed down by the core valve spring 47, and the second throttle passage 32 is closed by the valve pole 38. Then, the high pressure fuel from the common rail 3 is guided to the back pressure control chamber 27 through the first throttle passage 31, so that the nozzle needle 19 is pushed down through the valve piston 23 and the injection is performed. The hole 11 is closed and the injection ends.

As shown in FIG. 1, the return pipe 8 of the accumulator-type fuel supply device having the injector 4 configured as described above is used to supply the fuel flowing out through an overflow valve (not shown) provided to the fuel supply pump 2. Pipe that guides the fuel to the collector 52 attached to the common rail 3, and the fuel that is connected to the collector 52 and sent through the relay pipe 53 and the pressure in the common rail 3 is specified. Via an overpressure valve (not shown) that opens when the pressure exceeds It comprises a collecting pipe 54 that guides the fuel that has flowed out to the fuel tank 1, and a branch pipe 55 that has a connecting portion that connects to the fuel discharge port 48 of each injector 4.

 Then, a portion of the collecting pipe 54 downstream of the portion where the branch pipe 55 is connected, that is, a portion of the return pipe 8 downstream of the portion where the fuel leaking from the plurality of injectors 4 merges. An orifice 56 is formed to reduce the passage area of that portion.

 In the above configuration, each time each injector injects, the high-pressure fuel filled in the back pressure control chamber 27 is supplied to the branch pipe 55 through the second throttle passage 32, the actuator chamber 37, and the fuel discharge port 48. Pressure, the pressure in the branch pipe 55 and the collecting pipe 54 connected to the branch pipe 55 pulsates, but this pulsation is absorbed by the orifice 56 provided in the collecting pipe 54. Since it is possible to end immediately, it is possible to avoid a state in which the pressure in the branch pipe 55 is greatly pulsating at the time of the next injection, and the state in the branch pipe 55 can be avoided. It is possible to keep the pressure above atmospheric pressure.

A movable part having a large pressure receiving area, such as an anchor plate 43, is stored in the actuator chamber 37 of the injector 4, so that if the pressure in the actuator chamber 37 fluctuates greatly, the nozzle eddle 19 Will have an effect on the movement. In other words, when the time when the pressure in the actuator chamber 37 becomes low due to the large pulsation of the pressure and the injection time coincides with each other, the case where the actuator chamber 37 is maintained at the predetermined pressure is compared with the case where the predetermined pressure is maintained. The movement of the anchor plate 43 when power is supplied becomes agile, and the fuel oil in the back pressure control chamber 27 leaks rapidly, so that the nozzle-dollar 19 is immediately lifted and the injection amount increases. There is an inconvenience. However, as described above, the orifice 56 should be provided in the collecting pipe 54. Therefore, the pressure pulsation of the branch pipe 55 and the actuator chamber 37 of the injector 4 communicating therewith can be quickly terminated, and the pressure in that portion can be maintained at or above the atmospheric pressure. It is possible to suppress variations in the amount of blown-out air, prevent the occurrence of cavitation in the return pipe 8, and reduce erosion around the pole seat section 39 and the actuator chamber 37. Becomes possible. Actually, the diameter of the orifice 56 of the collecting pipe 54 is set to 1.5 mm, and the pressure sensor A disposed immediately before the orifice 56 and the collecting pipe 54 of the branch pipe 55 are set. When the pressure pulsation of the return pipe 8 was measured by the pressure sensor B disposed immediately above the injector 4 connected to the nearest part, the result as shown in FIG. 4 was obtained. Here, the pressure measured by pressure sensor A is indicated by a broken line, and the pressure measured by pressure sensor B is indicated by a solid line. In the case of rotation, Fig. 4 (b) shows the case where the engine speed is set to 200 rpm, and Fig. 4 (c) shows the case where the engine speed is set to 400 rpm. The case is shown.

 As is clear from the measurement results, at the time when each injector 4 injects, although the pressure in the branch pipe fluctuates greatly, this pressure pulsation can be quickly absorbed and terminated, and the return pipe The pressure inside 8 can now be kept higher than the atmospheric pressure. That is, although a large pressure pulsation occurs immediately in the vicinity of the injected injector 4, it is necessary to end the pressure pulsation of the branch pipe 55 by the next injection timing and to make the pressure in that portion higher than the atmospheric pressure. As a result, it is possible to suppress the injection φ variation in each injector 4.

In FIG. 5, the configuration shown in FIG. 1 is assumed, and between the injector 4 of the branch pipe 55 and the injector 4, and the most downstream side of the branch pipe 55. A configuration is shown in which an orifice 57 for reducing the passage area is formed between a portion connected to the injector and a portion connected to the collecting pipe 54 of the branch pipe 55. In such a configuration, in addition to the effect obtained by providing the orifice 56 in the collecting pipe 54 described above, the pressure pulsation in the branch pipe 55 generated at the time of injection of the injector 4 is reduced by the adjacent injector 4. This makes it difficult to convey the information, and makes it possible to further suppress fluctuations in the injection amount of the injector 4 that is injected next.

 For example, the diameter of the orifice 57 provided in the branch pipe 55 is set to 0.5 mm, the diameter of the orifice 56 of the collecting pipe 54 is set to 1.5 mm, and the pressure pulsation in the return pipe 8 is reduced. When measured, the results were obtained as shown in Figure 6. Here, the broken line indicates the result measured by the pressure sensor A, and the solid line indicates the result measured by the pressure sensor B. Fig. 6 (a) shows the case where the engine speed is 800 rpm, and Fig. 6 (b) shows the case where the engine speed is 200 rpm. 6 (c) shows the case where the engine rotation speed is set at 400 rpm. As can be seen from the measurement results, the pressure in the return pipe 8 at the time of injection by the injector 4 can be maintained at or above the atmospheric pressure, and the pressure pulsation generated at the time of injection by the injector 4 can be absorbed by the orifice 5.7. However, it is possible to end the pressure pulsation of the branch pipe 55 by the next injection timing, and thus it is possible to suppress the variation of the injection in each injector 4.

FIG. 7 shows another configuration example of the return pipe 8. In this example, a plurality of branch pipes 55 connected to the collecting pipe 54 are provided, and different injectors 4 having different injection timings are different. The configuration is such that they are connected to branch pipes 55a and 55b. For example, four injectors 4 are connected to the first cylinder injector (# 1) → the third cylinder injector (# 3) —the fourth cylinder injector When the injector (# 4) and the injector for the second cylinder (# 2) are fired in this order, and two branch pipes 55 are provided, the injector for the first cylinder (# 4) 1) and the fourth-cylinder injector (# 4) are connected to the branch pipe 55a, and the second-cylinder injector (# 2) and the third-cylinder injector (# 3) are branched. It is configured to connect to 55b. Since the other configuration is the same as the configuration shown in FIG. 1, the same portions are denoted by the same reference numerals and description thereof will be omitted.

 Therefore, by arranging such a branch pipe 55 separately, the branch pipe to which the injector 4 previously injected is connected and the branch pipe to which the injector 4 to be injected next is connected can be made different. This makes it difficult to transmit the previous pressure pulsation and makes it possible to increase the interval at which fuel leaks to the same branch pipe, so that the pressure pulsation can be more reliably terminated. It is possible to further suppress the variation in the injection in the rectifier 4.

 Actually, when the injector 4 is connected as described above using two branch pipes, the diameter of the orifice 56 of the collecting pipe 54 is set to 1.5 mm, and the pressure pulsation in the return pipe 8 is measured. The results were obtained as shown in FIG. Also in this case, the broken line shows the result measured by the pressure sensor A, and the solid line shows the result measured by the pressure sensor B. Fig. 8 (a) shows the case where the engine speed is 800 rpm, and Fig. 8 (b) shows the case where the engine speed is 200 rpm. FIG. 8 (c) shows the case where the engine speed is set at 400 rpm.

As is evident from the measurement results, the pressure in the return pipe 8 at the time of the injection of the injector 4 can be maintained at or above the atmospheric pressure, and the pressure pulsation generated at the time of the injection at the end of the injection is terminated by the next injection of the injector. This makes it possible to reduce the variation in injection at each injector 4. And it became possible.

 Further, on the premise of the configuration shown in FIG. 1, the return pipe 8 may be configured by a soft tube that can be elastically deformed by the pressure of the fuel oil leaking from the pressure control chamber 27 of the injector 4. Here, as the soft tube, an ordinary hose formed of a synthetic resin material or the like may be used, and with such a configuration, the pressure pulsation at the time of injection of each of the injectors 4 may be increased. Can be absorbed by the tube itself that constitutes the return pipe, and the pressure pulsation can be terminated before the next injector injection, thus suppressing the variation in injection at each injector 4. Becomes

 FIG. 9 shows the measurement results when a soft tube is used as the return pipe 8 and the diameter of the orifice 56 of the collecting pipe 54 is set to 1.5 mm. As is evident from the measurement results, the pressure in the return pipe 8 at the time of the injection of the injector 4 can be maintained at or above the atmospheric pressure, and the pressure pulsation generated at the time of the injection can be terminated by the next injection of the injector. As a result, it became possible to suppress variations in the emission of each injector 4.

 The configuration in which the orifice 57 is provided between the injectors described above, the configuration in which the branch pipe 55 is separated, and the configuration in which the return pipe is a soft tube are described in the case where the orifice 56 is simply provided in the collecting pipe 54. The pressure pulsation can be effectively reduced as compared with the above, but when these configurations are compared, the results shown in FIGS. 10 and 11 are obtained.

The graph shown in Fig. 10 shows how the pressure in the actuator chamber 37 at the start of injection changes when the injection timing is shifted, and the orifice 5 6 is connected to the collecting pipe 54. Compared to the case where only an orifice 57 is provided, a case where an orifice 57 is provided between the injectors and a branch passage 55 • If the return pipe 8 is made of a separate material and the return pipe 8 is made of a soft tube, the width of the pressure fluctuation can be further reduced. In particular, when the branch passage 55 is made a separate, the effect is large. there were. It was also confirmed that even when the orifice 57 was provided between the injectors, the pressure fluctuation became smaller as the orifice diameter was reduced.

 The characteristic line shown in FIG. 11 shows the result of measuring the injection amount of the pilot injection while shifting the injection timing (the interval T diff between the pilot injection and the main injection). In the conventional configuration without the provision of 56, the orifice 56 was provided in the force collecting pipe 54, where the injection amount of the pipe fluctuated greatly, so that the pressure in the return pipe was maintained at or above atmospheric pressure. In this case, it is possible to reduce the fluctuation of the injection amount.Furthermore, when an orifice 57 is provided between the injectors, and when a soft tube is used, the variation in the pipe injection amount is further reduced. We were able to.

 In the above-described configuration, the case where the orifice is used as a means for reducing the flow path area of the return pipe has been described. However, if the flow path area is reduced, the flow path area can be continuously varied. The flow path area may be reduced by a flow control valve or the like. Industrial applicability

As described above, according to the present invention, the valve body that opens and closes the injection hole and the back pressure through which fuel from the common rail is introduced to apply an operating force to the valve body in the direction that closes the nozzle hole The valve body is closed by leaking the oil pressure in the control chamber, the oil reservoir in which fuel from the common rail is introduced to apply an operating force to the valve body in the direction of opening the injection hole, and the back pressure control chamber to the low pressure side. Opening / closing valve that releases the operating force in the direction, and an actuator that controls the opening / closing operation of the opening / closing valve. A pressure-accumulating fuel supply device that includes an injector configured to include an ejector and returns the fuel leaked from the back pressure control chamber to a low pressure source via a return pipe connected to the injector. In the pipe, a throttle means for reducing the passage area is provided at a part downstream of the part where the fuel leaking from the plurality of injectors joins, so that the pressure fluctuation in the return pipe is reduced to exceed the atmospheric pressure. The pressure pulsation acting on the actuator of the injector can be reduced. As a result, a stable movement of the actuator of each injector can be ensured, so that the variation in the amount of oil injected from each injector can be suppressed, and the occurrence of cavitation in the return pipe can be prevented. In addition, it is possible to reduce the erosion of the actuator room around the ball seat. '

 In addition, if the return pipe is constituted by a common pipe to which a plurality of injectors are connected, and the throttle means for reducing the passage area is provided between the respective injectors, the pressure in the return pipe can be maintained at atmospheric pressure or higher. Above, it is possible to make it difficult for the pressure pulsation generated at the time of injector injection to be transmitted to the adjacent injectors, and it is possible to suppress variations in the amount of injection from each injector.

 Furthermore, if the return pipe is composed of a plurality of branch pipes connected to the injectors and a collecting pipe connected to these branch pipes, and different injectors with different injection timings are connected to different branch pipes, This makes it less likely to be affected by the previous injection, thereby reducing variations in the amount of oil injected from each injector.

Furthermore, if the return pipe is constituted by a soft tube that can be elastically deformed by the pressure of fuel oil leaking from the back pressure control chamber of the injector, the pressure pulsation generated at the time of injection of each injector is absorbed by the return pipe. The pressure pulsation in the return pipe can be terminated before another injector ejects, and the variation in the amount of oil injected from each injector can be suppressed.

Claims

The scope of the claims 1. It has a common rail that stores high-pressure fuel pumped from the fuel supply pump and a plurality of injectors that inject the high-pressure fuel stored in the common rail into the cylinders of the internal combustion engine. A valve body that opens and closes, a back pressure control chamber into which fuel oil from the common rail is introduced to apply an operating force to the valve body in a direction to close the injection hole, and a fuel oil in the back pressure control chamber And an actuating unit for controlling the opening and closing operation of the valve by opening and closing the valve so as to release the operating force of the valve body in the closing direction. In a pressure accumulating fuel injection device, fuel oil is returned to a low-pressure source via a return pipe connected to the injector.  A pressure-accumulation fuel injection device, wherein a throttle means for reducing a passage area is provided in a portion of the return pipe downstream of a portion where fuel oil leaking from the plurality of injectors joins.  2. The return pipe is constituted by a common pipe to which the plurality of injectors are connected, and a throttle means for narrowing a passage area is provided between each of the injectors. Accumulated fuel injection device as described 3. The return pipe is composed of a plurality of branch pipes for connecting the injectors and a collecting pipe to which the branch pipes are connected, and different injectors having different injection timings are connected to different branch pipes. The accumulator-type fuel injection device according to claim 1, wherein the fuel injection is performed. 4. The accumulator type fuel injection device according to claim 1, wherein the return pipe is constituted by a soft tube which can be elastically deformed by the pressure of fuel oil leaking from the back pressure control chamber of the injector. . FIG. 1

3/11 FIG. 3 5 7 33 3 4/11 (a)

 Hour. (b)

 Time (c)

Time

PUSO / ZOdT / lDd S6.800 / C0 OAV 6/11 (a)

(b)

FIG.6

(c) Time

Time FIG. 7

8/11 (a)

(b) Tokuji

Time 閬 9/11  FIG. 9

time FIG. 10 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05

 0  ^ a orifice + mouth- '  Fruit  orifice injection evening Orifice orifice orifice  +10 only 0 = 0.35 0 = 0,50 = 0.75 Senorate software Piping tube FIG. 11

 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5  1 diff (msec,