JP2019060292A - Fuel injection device - Google Patents

Abstract

To provide a fuel injection device capable of preventing the inside of a timer high pressure chamber from having negative pressure while securing timer characteristic of a timer mechanism of a fuel injection device.SOLUTION: In a fuel injection device including a feed pump for feeding a fuel to a pump chamber, and a timer mechanism for advancing or retarding a fuel injection timing by a pressure in the pump chamber, the timer mechanism includes a roller ring rotatably supported by a pump housing, a slide pin inserted to the roller ring at one end side and projected to an outer part of the roller ring at the other end side, a timer piston to which the other end side of the slide pin is inserted to drive the slide pin, a pressure chamber provided with a slide hole defined and formed by the timer piston for movably supporting the timer piston, and a first elastic member for energizing the timer piston to a pressure chamber side. The timer piston includes a first fuel passage and a second fuel passage for guiding a fuel of the pump chamber to the pressure chamber, and a check valve opened when the pressure in the pressure chamber is less than the pressure in the pump chamber by a prescribed value or more.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel injection device.

  A distributed fuel injection system in an internal combustion engine such as a diesel engine includes a timer mechanism for mechanically adjusting the fuel injection timing to the advance side or the retard side. The timer mechanism changes the rotational position of the roller ring with respect to the face cam, thereby changing the timing at which the cam ridge of the face cam rides on the roller ring and the timing at which it descends from the roller ring, and changes the timing at which the plunger reciprocates.

  The timer mechanism includes a roller ring rotatably supported by the pump housing, a slide pin whose one end is inserted through the roller ring, and a timer piston whose other end is inserted through the slide pin. By hydraulically driving the timer piston, the rotational position of the roller ring is changed.

  Specifically, as described in Patent Document 1, a sliding hole supporting the timer piston is partitioned by the timer piston to form a timer high pressure chamber. The timer high pressure chamber is divided by the slide hole, the timer piston and the timer cover. The timer piston is formed with a fuel passage for guiding the fuel of the pump chamber to the timer high pressure chamber, and the pressure of the pump chamber is supplied to the timer high pressure chamber. The timer piston is biased toward the timer high pressure chamber by a timer spring. When the pump rotational speed increases and the pressure in the pump chamber increases, the timer piston moves in a direction to contract the timer spring, and the roller ring rotates in the advance direction. Further, when the pump rotational speed decreases and the pressure in the pump chamber decreases, the timer piston moves to the timer high pressure chamber side by the timer spring, and the roller ring rotates in the retard direction.

Unexamined-Japanese-Patent No. 2003-239820

  Here, when the fuel injection ends when the pump rotational speed is high and the pressure in the pump chamber is high, the timer piston is rapidly returned to the timer low pressure chamber side by the driving reaction force due to the face cam being lifted down. An orifice is provided in the fuel passage which leads the fuel of the pump chamber to the timer high pressure chamber in order to ensure the stability of the timer characteristic. For this reason, when the timer piston moves to the timer low pressure chamber side, the fuel supply flow rate into the timer high pressure chamber runs short, so that the timer high pressure chamber becomes negative pressure, and a cavity is generated in the timer high pressure chamber. When this cavity is crushed, erosion may occur on the timer cover or the like, which may cause fuel leakage.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a fuel injection device capable of suppressing negative pressure in a timer high pressure chamber while securing timer characteristics of a timer mechanism of a fuel injection device. With the goal.

  In order to solve the above problems, according to one aspect of the present invention, a fuel provided with a feed pump for feeding fuel to a pump chamber, and a timer mechanism for advancing or retarding a fuel injection timing by pressure in the pump chamber. In the injection device, the timer mechanism includes a roller ring rotatably supported by the pump housing, a slide pin having one end inserted through the roller ring and the other end projecting outward of the roller ring, and the other end of the slide pin A timer piston inserted and driving a slide pin, a pressure chamber formed by dividing a slide hole for movably supporting the timer piston by the timer piston, and a first for urging the timer piston to the pressure chamber side An elastic member, wherein the timer piston is configured to provide a first fuel passage and a second fuel passage for guiding fuel in the pump chamber to the pressure chamber, and a pressure in the pressure chamber And a check valve which opens when a predetermined or more smaller than the pressure of the flop chamber, the fuel injection device is provided.

  As described above, according to the present invention, it is possible to suppress negative pressure in the timer high pressure chamber while securing the timer characteristic of the timer mechanism of the fuel injection device.

It is a schematic diagram which shows the structural example of the fuel-injection apparatus which concerns on this embodiment. It is a schematic diagram which shows the structural example of the timer mechanism of the fuel-injection apparatus concerning the embodiment. It is explanatory drawing which shows the retarding operation | movement of a timer mechanism. It is an explanatory view showing the advance operation of a timer mechanism. It is an explanatory view showing operation of a timer mechanism after fuel injection. It is an explanatory view showing operation of a timer mechanism after fuel injection. It is explanatory drawing which shows the pressure change in a timer high pressure chamber. It is explanatory drawing which shows the timer characteristic of the fuel-injection apparatus by a reference example. It is an explanatory view showing the timer characteristic of the fuel injection device concerning the embodiment.

  The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In the present specification and the drawings, components having substantially the same functional configuration will be assigned the same reference numerals and redundant description will be omitted.

(Example of configuration of fuel injection device)
First, a configuration example of a fuel injection device according to the present embodiment will be described. FIG. 1 is a schematic view partially showing a configuration example of a fuel injection device 1 according to the present embodiment.

  The fuel injection device 1 according to the present embodiment is a distributed fuel injection device applied to a diesel engine. The fuel injection device 1 includes a drive shaft 11, a feed pump 13, a drive gear 15, a roller ring 21, a pump housing 31, a plunger 25, a face cam 19, and a timer mechanism 70.

  The drive shaft 11 is rotationally driven in synchronization with the rotation of a crankshaft of a diesel engine (not shown) at a predetermined speed reduction ratio. The feed pump 13 is a vane type pump, is provided in the middle of the drive shaft 11 and is rotationally driven as the drive shaft 11 rotates. In FIG. 1, the feed pump 13 is shown together with a developed view rotated 90 degrees with respect to the axial direction of the drive shaft 11. A drive gear 15 for driving a governor (not shown) is attached to the proximal end side of the drive shaft 11. The drive gear 15 is connected to rotate integrally with the face cam 19 via a coupling 17.

  A roller ring 21 is provided between the drive gear 15 and the face cam 19. The roller ring 21 is provided with a plurality of cam rollers 23 facing the cam ridge 19 a of the face cam 19. The cam mountains 19a are provided in the same number as the number of cylinders of the diesel engine. A plunger 25 for fuel pressure is engaged with the face cam 19 so as to rotate integrally. The plunger 25 is pressed toward the face cam 19 by the plunger spring 27 and the lower seat 29, and reciprocates integrally with the face cam 19.

  The face cam 19 rotates integrally with the drive shaft 11 and rotates while engaging with the cam roller 23. When the face cam 19 is driven to reciprocate in the axial direction of the drive shaft 11 by the same number as the number of cylinders while rotating, the plunger 25 is driven to reciprocate in the same direction while axially rotating. That is, the plunger 25 is lifted up in the process in which the cam lobe 19a rides on the cam roller 23 of the roller ring 21, and the plunger 25 is lifted down in the process in which the cam lobe 19a descends from the cam roller 23 of the roller ring 21.

  The pump housing 31 is provided with a plunger barrel 33 having a slide hole 33 a into which the plunger 25 is inserted. A pressure chamber 35 is formed between the tip end surface of the plunger 25 and the bottom surface of the slide hole 33 a. On the outer peripheral surface on the tip end side of the plunger 25, suction grooves 37 equal in number to the number of cylinders are formed. The suction groove 37 communicates with the pump chamber 43 via the suction port 41 formed in the pump housing 31 when the plunger 25 lifts down and the pressure chamber 35 is depressurized, and adds fuel of the pump chamber 43. It leads to the pressure chamber 35.

  A distribution port 39 for guiding pressurized fuel to a discharge port 45 formed in the pump housing 31 is formed inside the tip end side of the plunger 25. The discharge ports 45 are also opened in the plunger barrel 33, and provided at equal intervals as many as the number of cylinders of the diesel engine. At the outlet portion of the discharge port 45, a delivery valve 47 is disposed. The delivery valve 47 is for preventing the backflow of the fuel pressure-fed from the discharge port 45, and opens when the predetermined fuel pressure is reached, so that the high pressure fuel pressure-fed to the discharge port 45 can be externally pressurized. The fuel is discharged toward the fuel injection nozzle 48 through the pipe 49.

  The pump housing 31 is formed with an introduction port 51 communicated with the fuel tank via an inlet (not shown). The introduction port 51 communicates the suction side of the feed pump 13 with the inlet. The introduction port 51 also communicates with a timer low pressure chamber 71 of a timer mechanism 70 described later. Inside the pump housing 31, a pump chamber 43 for receiving the fuel supply from the feed pump 13 is formed. The pump chamber 43 holds the fuel drawn into the pressurizing chamber 35, guides the fuel to a mechanical sliding portion such as the plunger 25 or the plunger barrel 33, and functions as a lubricating oil.

  When driven by the rotation of the drive shaft 11, the feed pump 13 introduces fuel from the fuel tank into the introduction port 51 and sucks it into the feed pump 13. The fuel sucked into the feed pump 13 is pressure-fed to an outlet port (not shown) formed in the pump housing 31 and supplied to the pump chamber 43.

  In the suction stroke where the plunger 25 lifts down and the pressure chamber 35 is depressurized, one of the suction grooves 37 formed on the outer periphery of the tip of the plunger 25 communicates with the pump chamber 43 via the suction port 41, The fuel in the pump chamber 43 is drawn into the pressure chamber 35. Further, in the compression stroke where the plunger 25 lifts up and the pressurizing chamber 35 is pressurized, the high pressure fuel pressurized in the pressurizing chamber 35 passes through the discharge port 45, the delivery valve 47 and the fuel pumping pipe 49. The pressure is fed to the fuel injection nozzle 48. When the pressure of the pumped fuel reaches the nozzle opening pressure, the fuel injection nozzle 48 injects the fuel into the cylinder of the diesel engine.

  In addition to this, the fuel injection device 1 is provided with a solenoid on-off valve for performing a fuel cut and the like, and a governor mechanism for controlling a fuel injection characteristic.

  The timer mechanism 70 mechanically adjusts the fuel injection timing to the advance side or the retard side. The timer mechanism 70 is provided at the lower part of the pump housing 31. The timer mechanism 70 has a timer housing 75 having a slide hole 75 a provided in a direction orthogonal to the axial direction of the drive shaft 11. In the slide hole 75a, a timer piston 77 is disposed so as to be capable of reciprocating displacement. The axial direction of the slide hole 75 a and the timer piston 77 extends in a direction orthogonal to the axial direction of the drive shaft 11. Note that, in FIG. 1, the timer mechanism 70 is shown in a state where the axial direction of the sliding hole 75 a and the timer piston 77 is rotated by 90 degrees.

  The timer mechanism 70 changes the rotational position of the roller ring 21 with respect to the rotational direction of the drive shaft 11 to change the timing when the cam ridge 19 a rides on the cam roller 23 and the timing when it descends from the cam roller 23. As a result, the timing at which the plunger 25 reciprocates is changed. That is, the roller ring 21 is rotatably supported on the pump housing 31 so that the rotational position is changed by the timer mechanism 70.

  The timer mechanism 70 is driven by oil pressure. The timer piston 77 is connected to the roller ring 21 via a slide pin 79. One end of the slide pin 79 is inserted into the roller ring 21, and the other end is inserted into the cylindrical hole 83 of the timer piston 77 so as to protrude outward of the roller ring 21. The slide pin 79 transmits the axial movement of the timer piston 77 to the roller ring 21 to change the rotational position of the roller ring 21.

  A timer low pressure chamber 71 communicating with the introduction port 51 is formed at one end of the timer piston 77, and a timer high pressure chamber 73 communicating with the pump chamber 43 is formed at the other end. In the present embodiment, the timer high pressure chamber 73 corresponds to the pressure chamber of the present invention. The timer low pressure chamber 71 is provided with a timer spring 81 that biases the timer piston 77 toward the timer high pressure chamber 73. The fuel pressurized by the feed pump 13 and supplied to the pump chamber 43 is introduced into the timer high pressure chamber 73.

  The position of the timer piston 77 is determined by the fuel pressure introduced into the timer high pressure chamber 73, the biasing force of the timer spring 81, and the force by which the force acting on the roller ring 21 is transmitted to the timer piston 77 via the slide pin 79. Determined by the balance of The force acting on the roller ring 21 is a force acting on the roller ring 21 when the cam ridge 19 a of the face cam 19 rides on the cam roller 23 or descends from the cam roller 23. The position of the roller ring 21 is determined in accordance with the position of the timer piston 77, and the advance timing for reciprocating the plunger 25 is determined.

(Specific configuration example of timer mechanism)
Next, a specific configuration example of the timer mechanism 70 of the fuel injection device 1 according to the present embodiment will be described. FIG. 2 is a schematic view showing a configuration example of the timer mechanism 70. As shown in FIG.

  The timer mechanism 70 includes a timer housing 75 having a slide hole 75a therein. In the slide hole 75a, a timer piston 77 is disposed movably in the axial direction. The timer piston 77 divides the slide hole 75 a into the timer low pressure chamber 71 and the timer high pressure chamber 73. At one end of the timer piston 77, a timer high pressure chamber 73 is formed by the timer piston 77, the timer housing 75, and the high pressure timer cover 93. At the other end of the timer piston 77, a timer low pressure chamber 71 is formed by the timer piston 77, the timer housing 75, and the low pressure side timer cover 91. The timer low pressure chamber 71 is provided with a timer spring 81. The timer spring 81 always biases the timer piston 77 to the timer high pressure chamber 73 side. In the present embodiment, the timer spring 81 has a function as a first elastic member of the present invention.

  The cylindrical hole 83 of the timer piston 77 is formed to extend in a direction orthogonal to the axial direction of the timer piston 77. In the cylindrical hole 83, an axial movement of the timer piston 77 is transmitted to the slide pin 79, and a sub-piston 111, which suppresses wear of the slide pin 79 and the timer piston 77, is rotatably inserted. The end of the slide pin 79 is inserted into the insertion hole 111 a of the sub piston 111 so as to be rotatably connected to the timer piston 77.

  The timer piston 77 is constantly urged by the timer spring 81 toward the timer high pressure chamber 73, that is, the slide pin 79 is biased in the retard direction to rotate the roller ring 21 in the rotational direction of the drive shaft 11. As the rotational speed of feed pump 13 increases, the pressure in timer high pressure chamber 73 receiving the supply of fuel from pump chamber 43 rises, and timer piston 77 resists the biasing force of timer spring 81 and timer low pressure chamber 71 Move to the side. Along with this, the slide pin 79 rotates the roller ring 21 in the direction (advance direction) opposite to the rotation direction of the drive shaft 11, and the fuel injection timing is advanced.

  In the timer piston 77, a first fuel passage 101 and a second fuel passage 103 for guiding the fuel of the pump chamber 43 to the timer high pressure chamber 73 are formed. The first fuel passage 101 has a small diameter portion 101a functioning as an orifice and a large diameter portion 101b connected to the small diameter portion 101a. The small diameter portion 101 a is located on the pump chamber 43 side, and the large diameter portion 101 b is located on the timer high pressure chamber 73 side. The first fuel passage 101 always communicates the pump chamber 43 with the timer high pressure chamber 73.

  The second fuel passage 103 has a small diameter portion 103a and a large diameter portion 103b connected to the small diameter portion 103a. The small diameter portion 103 a is located on the pump chamber 43 side, and the large diameter portion 103 b is located on the timer high pressure chamber 73 side. The second fuel passage 103 can communicate with the pump chamber 43 through a slit-like fuel passage 113 formed on the peripheral surface of the sub piston 111. A valve body 105, a valve spring 109, and a spring receiving member 107 are provided in the large diameter portion 103b. The spring receiving member 107 is fixed in the large diameter portion 103b by press fitting or the like. The spring receiving member 107 has a fuel passage hole 107a for communicating the inside of the large diameter portion 103b to the timer high pressure chamber 73 side.

  The valve body 105 is disposed at the opening of the small diameter portion 103 a and is always urged toward the small diameter portion 103 a, that is, in the valve closing direction, by a valve spring 109 disposed between the valve body 105 and the spring receiving member 107. ing. In the present embodiment, the valve spring 109 has a function as a second elastic member of the present invention. The stepped surface which is the boundary between the small diameter portion 103a and the large diameter portion 103b has a function as a valve seat surface. The valve body 105 receives the pressure in the pump chamber 43 from the small diameter portion 103 a side, and receives the pressure in the timer high pressure chamber 73 from the large diameter portion 103 b side. Therefore, the sum of the pressure in the pump chamber 43 biasing the valve body 105 in the valve opening direction, the pressure in the timer high pressure chamber 73 biasing the valve body 105 in the valve closing direction, and the biasing force of the valve spring 109 The position of the valve body 105 is determined by the balance of

  The configurations of the valve body 105, the valve spring 109 and the spring receiving member 107 function as the check valve 5. That is, when the pressure in the timer high pressure chamber 73 is smaller than the pressure in the pump chamber 43 by a predetermined amount or more, the check valve 5 opens, and fuel is transferred from the pump chamber 43 to the timer high pressure chamber 73 through the second fuel passage 103. Led. On the other hand, when the pressure in the timer high pressure chamber 73 is smaller than the pressure in the pump chamber 43 by a predetermined amount or more, the check valve 5 is closed and the second fuel passage 103 is shut off.

(Operation of timer mechanism)
Next, the operation of the timer mechanism 70 will be described with reference to FIGS. FIG. 3 shows a state where the timer piston 77 is positioned at the most retarded side, and FIG. 4 shows a state where the timer piston 77 has moved in the advance direction. 5 to 6 show the behavior of the timer piston 77 after the end of fuel injection.

  FIG. 3 shows the case where the rotational speed of the feed pump 13 is low and the pressure in the pump chamber 43 is low in the operating state of the diesel engine. In this case, the pressure in the timer high pressure chamber 73 does not become smaller than the pressure in the pump chamber 43 by a predetermined amount or more, so the check valve 5 provided in the second fuel passage 103 is maintained closed. The fuel in the pump chamber 43 is led to the timer high pressure chamber 73 via the first fuel passage 101. Further, in this state, the pressure in the timer high pressure chamber 73 does not exceed the biasing force of the timer spring 81, and the timer piston 77 is held at the most retarded side.

  FIG. 4 shows the case where the rotational speed of the feed pump 13 is increased and the pressure in the pump chamber 43 is increased. In this case, the fuel is introduced to the timer high pressure chamber 73 through the first fuel passage 101, and the pressure in the timer high pressure chamber 73 also rises. Therefore, since the pressure in the timer high pressure chamber 73 does not become smaller than the pressure in the pump chamber 43 by a predetermined amount or more, the check valve 5 provided in the second fuel passage 103 is maintained in the closed state. Then, when the pressure in the timer high pressure chamber 73 exceeds the biasing force of the timer spring 81, the timer piston 77 moves in the advance direction.

  FIG. 5 shows the case where fuel injection is performed in the state of high pressure and high revolution shown in FIG. When the fuel injection is completed, the timer piston 77 rapidly starts to move to the timer low pressure chamber 71 side by receiving the driving reaction force due to the face cam 19 being lifted down through the slide pin 79. The driving reaction force is a force caused by the force that the above-described roller ring 21 receives from the face cam 19. In an initial state where the timer piston 77 starts to move to the timer low pressure chamber 71 side, the check valve 5 provided in the second fuel passage 103 is closed, and the pump via the first fuel passage 101 having the small diameter portion 101a Since the fuel supply flow rate to the chamber 43 is not sufficient, the pressure in the timer high pressure chamber 73 drops rapidly.

  Then, as shown in FIG. 6, the pressure in the timer high pressure chamber 73 becomes smaller than the pressure in the pump chamber 43 by a predetermined amount or more, and the check valve 5 provided in the second fuel passage 103 is opened. Therefore, the fuel in the pump chamber 43 is supplied to the timer high pressure chamber 73 via the first fuel passage 101 and the second fuel passage 103. Therefore, the fuel supply flow rate from the pump chamber 43 to the timer high pressure chamber 73 is sufficiently secured, and the negative pressure in the timer high pressure chamber 73 can be suppressed.

(Pressure change in timer high pressure chamber)
FIG. 7 is an explanatory view showing a pressure change in the timer high pressure chamber 73 accompanying the lift-down (L.D.) of the face cam 19 when the fuel injection device is driven in the high pressure high revolution state. In FIG. 7, a solid line shows an example of the fuel injection device 1 according to the present embodiment, and a broken line shows an example of a fuel injection device according to a reference example without the second fuel passage 103 provided with the check valve 5. There is.

  In any of the embodiment and the reference example, when the face cam 19 is lifted, the timer piston 77 receives the driving reaction force of the face cam 19 through the slide pin 79 and moves to the timer high pressure chamber 73 side. The pressure in the chamber 73 is rising.

  Further, in any of the embodiment and the reference example, at the time of lift-down of the face cam 19, the timer piston 77 receives the driving reaction force of the face cam 19 via the slide pin 79 and rapidly moves to the timer low pressure chamber 71 side. The pressure in the timer high pressure chamber 73 drops rapidly. At this time, in the reference example, since the fuel is introduced from the pump chamber 43 to the timer high pressure chamber 73 only through the first fuel passage 101, the fuel supply flow rate is insufficient, and the pressure in the timer high pressure chamber 73 is negative. It has become.

  On the other hand, in the embodiment, as the pressure in the timer high pressure chamber 73 decreases, the check valve 5 is opened, and the pump chamber 43 to the timer high pressure chamber via the second fuel passage 103 together with the first fuel passage 101. Fuel is led to 73. Therefore, the fuel supply flow rate is secured, and the negative pressure in the timer high pressure chamber 73 is avoided. Therefore, the erosion due to the generation of the cavity in the timer high pressure chamber 73 can be reduced.

(Timer responsiveness)
8 and 9 are diagrams for explaining the responsiveness of the timer mechanism 70. FIG. The horizontal axis indicates the pump rotational speed (the rotational speed of the drive shaft 11), and the vertical axis indicates the movement amount (TA) of the timer piston 77. FIG. 8 shows the response of the timer mechanism of the fuel injection device according to the reference example having no check valve 5 and the second fuel passage 103. FIG. 9 shows the timer mechanism of the fuel injection device 1 according to the present embodiment. It shows the responsiveness of 70.

  As shown in FIG. 8, in the fuel injection device according to the reference example, a difference of up to 2.6 mm occurs in the movement amount of the timer piston 77 at the same pump rotational speed between the case where the pump rotational speed increases and the case where the pump rotational speed decreases. ing. On the other hand, as shown in FIG. 9, in the fuel injection device 1 according to the present embodiment, the amount of movement of the timer piston 77 at the same pump rotational speed is at most 1. It is suppressed to 3 mm. This is because the second fuel passage 103 is closed except when the pressure in the timer high pressure chamber 73 is smaller than the pressure in the pump chamber 43 by a predetermined amount or more, and the first fuel passage appropriately designed as an orifice The fuel is introduced from the pump chamber 43 to the timer high pressure chamber 73 through the small diameter portion 101 a of 101.

  That is, in order to secure the fuel supply flow rate from the pump chamber 43 to the timer high pressure chamber 73, the pressure in the timer high pressure chamber 73 is higher than the pressure in the pump chamber 43, not merely increasing the cross sectional area of the small diameter portion 101a. It is also effective to open the second fuel passage 103 when the second fuel passage 103 is smaller than a predetermined value. Thus, the fuel injection device 1 according to the present embodiment can improve the stability or the linearity of the timer mechanism 70.

<Summary>
As described above, the fuel injection device 1 according to the present embodiment is combined with the first fuel passage 101 having the small diameter portion 101a functioning as an orifice as a fuel passage for guiding the fuel from the pump chamber 43 to the timer high pressure chamber 73. The second fuel passage 103 is provided with a check valve 5 that opens when the pressure in the timer high pressure chamber 73 is smaller than the pressure in the pump chamber 43 by a predetermined amount or more. Therefore, when the fuel injection is finished with the fuel injection device driven at high pressure and high speed, the timer piston 77 rapidly moves to the timer low pressure chamber 71 side, and the pressure in the timer high pressure chamber 73 sharply. Even in the case of descent, fuel can be supplied to the timer high pressure chamber 73 relatively quickly. As a result, the negative pressure in the timer high pressure chamber 73 is suppressed, and the erosion due to the crush of the cavity can be suppressed.

  Further, the fuel injection device 1 according to the present embodiment transfers the pressure to the timer high pressure chamber 73 through the small diameter portion 101 a of the first fuel passage 101 except when the pressure in the timer high pressure chamber 73 drops sharply. Since the fuel is supplied, the responsiveness of the timer can be improved.

  Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention belongs can conceive of various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also fall within the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Fuel injection apparatus, 5 ... Check valve, 19 ... Face cam, 19a ... Cam mountain, 21 ... Roller ring, 23 ... Cam roller, 43 ... Pump chamber, 70 ... timer mechanism, 71 ... timer low pressure chamber, 73 ... timer high pressure chamber, 77 ... timer piston, 79 ... slide pin, 81 ... timer spring, 101 ... first Fuel passage, 101a: small diameter portion, 103: second fuel passage, 105: valve body, 107: spring receiving member, 109: valve spring

Claims (3)

A fuel injection system comprising: a feed pump for feeding fuel to a pump chamber; and a timer mechanism for advancing or retarding a fuel injection timing by pressure in the pump chamber,
The timer mechanism
A roller ring rotatably supported on the pump housing;
A slide pin having one end inserted through the roller ring and the other end protruding outward of the roller ring;
A timer piston into which the other end of the slide pin is inserted and which drives the slide pin;
A pressure chamber formed by dividing the sliding hole for movably supporting the timer piston by the timer piston;
And a first elastic member for urging the timer piston toward the pressure chamber.
The timer piston is
A first fuel passage and a second fuel passage for guiding the fuel of the pump chamber to the pressure chamber;
A check valve which opens when the pressure in the pressure chamber is smaller than the pressure in the pump chamber by a predetermined amount or more.   The fuel injection device according to claim 1, wherein the second fuel passage is a passage provided independently of the first fuel passage. The second fuel passage has a small diameter portion on the pump chamber side and a large diameter portion on the pressure chamber side,
The fuel injection device according to claim 1 or 2, wherein the large diameter portion is provided with a valve body and a second elastic member that biases the valve body toward the small diameter portion.

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