JP3918767B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device, and more particularly to a fuel injection timing control device for a fuel injection device.
[0002]
[Prior art]
As a fuel injection device, for example, in a distributed fuel injection pump used in a fuel injection device of a diesel engine, a fuel injection timing control device provided with a servo valve is known (see Patent Document 1). In the technique according to the disclosure of Patent Document 1, a servo valve is slidably supported in an insertion hole formed in a timer piston. This servo valve slides in the insertion hole due to a change in the pressure of the fuel oil supplied from the feed pump. When the supply pressure rises, fuel oil is supplied from the feed pump to the high-pressure chamber, and the timer piston moves to the advance side. On the other hand, when the supply pressure decreases, the servo valve is opened to connect the high pressure chamber and the low pressure chamber, and the timer piston is moved to the retard side. This type of fuel injection timing control device has a higher control force than a device without a servo valve and is not easily affected by the pump drive reaction force, and is currently widely used as a servo timer mechanism.
[0003]
Note that the high pressure chamber and the low pressure chamber are formed with a timer piston interposed therebetween, and for example, the high pressure chamber is formed of a timer piston and a high pressure side timer cover.
[0004]
In recent years, in industrial machines such as construction machinery, exhaust gas regulations for diesel engines are being strengthened in the same manner as vehicles such as passenger cars. Along with this, there is a demand for practical use of a load timer mechanism (see Patent Document 2) capable of obtaining a reverse advance angle characteristic as an exhaust gas purification measure in a low load region. In the technique according to the disclosure of Patent Document 2, the conventional advance angle characteristic is retarded as the load decreases, whereas, it is retarded as the load increases.
[0005]
[Patent Document 1]
JP 58-32928 A
[0006]
[Patent Document 2]
Actual opening and closing 4-1644
[0007]
[Problems to be solved by the invention]
In the technique disclosed in the above publication, if a fuel injection device having a servo timer mechanism and a load timer mechanism having a reverse advance angle characteristic is to be put into practical use, the timer piston is in the most retarded state in a high load range. Press the high-pressure timer cover. Since a high driving reaction force acts on the timer piston, cavitation erosion may occur on the end surface of the timer piston on the high pressure side due to the generation of a cavity in the high pressure chamber due to distortion of the high pressure side timer cover.
[0008]
The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to provide a fuel injection device that has a servo timer mechanism and a load timer mechanism having a reverse advance angle characteristic and can prevent the occurrence of erosion. It is to provide.
[0009]
[Means for Solving the Problems]
  According to the first aspect of the present invention, the feed pump for supplying fuel into the pump chamber, the governor shaft disposed in the pump chamber, and the outer periphery of the governor shaft are slidably fitted on the outer periphery of the governor shaft so as to open the flyweight. The governor has a governor sleeve that moves forward in the axial direction in conjunction and moves back in the axial direction in conjunction with the closing operation of the flyweight, and when the fuel in the pump chamber is at high pressure, the fuel injection timing is advanced and the pressure is low. In a fuel injection device having a timer mechanism that sometimes retards fuel injection timing, an escape passage formed inside the governor shaft, having one end opened on the outer peripheral surface of the governor shaft and the other end communicating with the low pressure side of the fuel And is formed in the governor sleeve, penetrates the inner and outer surfaces of the fitting portion with the governor shaft, and is blocked from the escape passage when the governor sleeve advances. And having a through hole communicating with the passage relief during retraction,
  The timer mechanism includes a timer piston engaged with a roller ring capable of adjusting the fuel injection timing, and a high-pressure timer cover having a locking portion that regulates the most retarded position of the timer piston, and slides the timer piston. The sliding hole that is supported freely is divided into two pressure chambers. One of the pressure chambers receives the driving torque reaction force acting on the roller ring through the timer piston, and is a high pressure chamber partitioned by the high pressure side timer cover. The other is a low-pressure chamber that communicates with the low-pressure side of the fuel, the servo valve insertion hole that is formed in the timer piston and opens to the low-pressure chamber, the inflow passage to which fuel is supplied to the pump chamber, and the high-pressure chamber communicates with the servo valve It has a fuel passage that opens in the insertion hole and a servo valve that can slide in the servo valve insertion hole.
  The servo valve receives the pressure of the fuel in the pump chamber guided from the inflow passage at one end, the servo valve spring is biased against the fuel pressure at the other end, and the fuel is changed according to the pressure change of the fuel in the pump chamber. The passage and the low-pressure chamber can be communicated and blocked.
  The high pressure side timer cover is provided with a stepped portion extending in a direction away from the timer piston in the locking portion,
  And the locking part extends into the sliding hole, and the outer periphery of the locking part and the sliding hole are loosely fitted,
The high-pressure timer cover is a separate member from the housing in which the sliding hole is formed, and further includes a flange portion for closing the sliding hole,
A seal member is inserted between the flange portion and the housing.
[0010]
First, the through hole of the governor sleeve is cut off from the escape passage when the governor sleeve moves forward, and constitutes a load timer structure that communicates with the escape passage when the governor sleeve moves backward. The fuel in the room flows out to the low pressure side through the escape passage. As a result, this load timer structure retards the fuel injection timing in the timer mechanism in a high load state as compared with the low load region.
[0011]
Further, the timer mechanism has a servo valve that is slidably supported in a servo valve insertion hole formed in the timer piston, and a second end that opposes the fuel pressure in the pump chamber applied to one end of the servo valve. A servo valve spring is provided to move the position of the servo valve in accordance with a change in fuel pressure in the pump chamber. As a result, the fuel piston communicating with the high pressure chamber and the low pressure chamber communicate with each other, and the timer piston is controlled to a timer piston position at which switching is performed.
[0012]
Further, when the timer piston is in the most retarded state in the high load region, the high pressure side timer cover is deformed and the volume in the high pressure chamber is increased by the timer piston pressing the high pressure side timer cover by the driving torque reaction force. .
[0013]
On the other hand, the high pressure side timer cover having a locking portion that regulates the most retarded angle position of the timer piston is provided with a stepped portion that extends in a direction away from the timer piston in the locking portion. Even when the timer piston is in the most retarded angle state, a predetermined volume of fuel space defined by the stepped portion and the timer piston is formed. The volume of the high pressure chamber in the most retarded state is increased by a predetermined volume. Thereby, even if deposition in the high-pressure chamber increases due to deformation of the high-pressure timer cover, the volume change rate can be reduced. Therefore, since the volume change rate can be reduced or made small, the generation of negative pressure can be prevented or suppressed.
[0014]
Further, when the high-pressure timer cover is deformed, even if the high-pressure chamber and the low-pressure chamber are communicated via the fuel passage by the servo valve, the fuel in the high-pressure chamber has at least a predetermined volume, so that all the fuel in the high-pressure chamber immediately It is possible to avoid leakage. As a result, it is possible to prevent the negative pressure from being induced by the communication operation of the servo valve.
[0015]
As a result, it is possible to prevent the formation of cavities caused by the generation of negative pressure, thereby preventing the occurrence of cavitation erosion.
[0016]
According to the second and third aspects of the present invention, the stepped portion can be easily formed by cutting or forging. A fuel injection device capable of preventing the occurrence of cavitation erosion can be provided at a low cost.
[0017]
  Note that, as means for securing a predetermined volume in the most retarded state of the timer piston, from claim 1Claim 4In either case, since the step portion is provided in the high-pressure timer cover, a large predetermined volume can be secured.
[0018]
According to claim 4 of the present invention, the locking portion has a substantially annular portion. As a result, it is possible to secure a contact surface on which the end surface of the timer piston on the high pressure chamber side and the locking portion can stably contact.
[0019]
  Even if negative pressure does not occur, the driving torque reaction force generated at each fuel injection acts on the timer piston and cancels the action, so that the fuel pressure in the high-pressure chamber fluctuates rapidly.In particularThe locking part extends into the sliding hole, and the outer periphery of the locking part and the sliding hole are preferably loosely fitted.
[0020]
Thereby, the clearance gap between the outer periphery of a latching | locking part and a sliding hole is narrowed so that it may fit. For example, when a sealing member such as an O-ring is inserted between the high-pressure timer cover and the sliding hole side to ensure oil tightness to the outside, the pressure of the fuel in the high-pressure chamber is applied to the sealing member by the clearance. Direct propagation is prevented. Therefore, it is possible to protect the seal member from a sudden pressure fluctuation of the fuel in the high pressure chamber due to the influence of the driving torque reaction force.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A specific embodiment of a fuel injection device of the present invention will be described with reference to the drawings.
[0022]
(First embodiment)
FIG. 1 is a cross-sectional view showing a timer mechanism according to the fuel injection device of the present embodiment. 2A and 2B are diagrams showing the high-pressure side timer cover in FIG. 1, in which FIG. 2A is a cross-sectional view, and FIG. 2B is a plan view as seen from A in FIG. FIG. 3 is a longitudinal sectional view showing the load timer mechanism according to the present embodiment. 4A and 4B are graphs showing an advance angle characteristic by a load timer mechanism. FIG. 4A is a reverse advance characteristic that is retarded as the load increases, and FIG. 4B is a comparison that is retarded as the load is decreased. It is a graph which shows the advance angle characteristic of an example. FIG. 5 is a longitudinal sectional view showing the fuel injection device of the present embodiment.
[0023]
As shown in FIG. 5, a drive shaft 2 that is rotationally driven by a diesel engine is mounted on a fuel injection device 1 that pumps fuel to each cylinder of a diesel engine (not shown). A vane type feed pump 3 is provided in the middle of the drive shaft 2, and the feed pump 3 is driven to rotate as the drive shaft 2 rotates.
[0024]
A drive gear 5 for driving the governor 4 is attached to the base end side of the drive shaft 2. The governor 4 will be described later. A roller ring 7 is disposed between the drive gear 5 and the cam plate 6. A plurality of cam rollers 8 facing the cam crest face 6 a of the cam plate 6 are attached to the roller ring 7. The number of cam mount faces 6a is the same as the number of cylinders of the diesel engine. The cam plate 6 is pressed against the cam roller 8 by a spring 9.
[0025]
The cam plate 6 has a fuel pressurizing plunger 10 attached thereto, and rotates integrally with the drive shaft 2 via a coupling 11. The coupling 11 is inserted with a claw 6b provided on the cam plate 6 and a claw 5a provided on the drive shaft 2, and the cam plate 6 rotates integrally with the drive shaft.
[0026]
The cam nose face 6 a is in rolling contact with the cam roller 8. When the cam roller 8 is brought into rolling contact with the cam crest face 6a, the cam plate 6 and the plunger 10 reciprocate a plurality of times during one rotation by the drive shaft, that is, a plurality of times according to the number of cylinders of the engine. That is, the cam crest face 6a moves forward (lifts up) in the process of riding on the cam roller 8 of the roller ring 7, and conversely, the plunger 10 moves back (lifts up) in the process of the cam crest face 6a getting on and off the cam roller 8 of the roller ring 7. Down).
[0027]
The pump housing 12 is provided with a cylinder 13 arranged with the plunger 10 inserted. A plunger high pressure chamber 14 is formed between the tip of the plunger 10 and the head plug 13 a forming the bottom surface of the cylinder 13. The same number of suction grooves 15 a as the number of cylinders are formed on the outer periphery of the plunger 10 on the tip side. The suction groove 15a communicates with a pump chamber 16 to be described later via a suction port 15 formed in the pump housing 12 when the plunger 10 moves backward and the high pressure chamber 14 is depressurized. This is for guiding the fuel to the plunger high pressure chamber 14. Further, a distribution port for guiding the compressed fuel to a discharge port 17 formed in the pump housing 12 is formed inside the distal end side of the plunger 10. The discharge port 17 opens into the cylinder 13 at equal intervals by the number of cylinders of the diesel engine.
[0028]
A delivery valve 20 is disposed at the outlet portion of the discharge port 17. This delivery valve 20 is for preventing the reverse flow of fuel pumped from the discharge port 17 to a fuel pumping pipe (not shown), and is opened when a certain fuel pressure is reached. The high-pressure fuel pumped to 17 is guided to the fuel pumping pipe.
[0029]
In addition, an inlet (not shown) connected to a fuel tank (not shown) is attached to the pump housing 12. This inlet communicates with the suction side of the feed pump 3 via the introduction port 23 (corresponding to the low pressure side of the fuel). The introduction port 23 also communicates with a low pressure chamber 25 (see FIG. 1) of a timer mechanism 24 described later.
[0030]
A pump chamber 16 that receives supply of fuel from the feed pump 3 is formed inside the pump housing 12. The pump chamber 16 stores fuel sucked into the plunger high-pressure chamber 14 and fills the mechanical sliding portions such as the plunger 10 and the cylinder 13 with fuel.
[0031]
When the feed pump 3 is driven by the rotation of the drive shaft 2, the fuel is introduced from the fuel tank through the inlet into the introduction port 23 and sucked into the feed pump 3. The fuel sucked into the feed pump 3 is pumped to an outlet port (not shown) and supplied to the pump chamber 16.
[0032]
Here, in the suction stroke in which the plunger 10 moves backward and the plunger high-pressure chamber 14 is depressurized, one of the suction grooves 15 a formed on the outer periphery of the tip of the plunger 10 communicates with the pump chamber 16 through the suction port 15. The fuel in the pump chamber 16 is sucked into the plunger high pressure chamber 14. Conversely, in the compression stroke in which the plunger 10 moves forward and the plunger high pressure chamber 14 is pressurized, the high pressure fuel pressurized in the high pressure chamber 14 passes through the discharge port 17, the delivery valve 20, and the fuel pressure feed pipe. It is pumped to one of the fuel injection nozzles (not shown) attached to each cylinder of the engine. When the pressure of the pumped fuel reaches the nozzle opening pressure, the fuel injection nozzle injects fuel into the cylinder.
[0033]
On the other hand, the plunger 10 is formed with a spill port 32 having one end communicating with the distribution port 18 and overflowing the high pressure fuel compressed in the high pressure chamber 14 into the pump chamber (hereinafter referred to as spilling). The other end of the spill port 32 opens in the pump chamber 16, and a ring-shaped spill ring 33 that opens and closes the spill port 32 is slidably fitted around the plunger 10. Since the fuel injection ends when the spill port 32 is exposed from the spill ring in the pressure stroke of the plunger 10, the fuel injection amount increases when the spill ring 33 is moved to the right side of FIG. The injection amount decreases.
[0034]
The spill ring 33 is engaged with the end of the control lever 34 of the lever assembly 35, and the position is set according to the rotational position of the control lever 34. The lever assembly 35 mainly includes a guide lever 36 whose rotational position is set with respect to the pump housing wing 12, and a tension lever 38 and a control lever 34 that are rotatably mounted via a support shaft 37 of the guide lever 36. This is a component.
[0035]
The control lever 34 is in contact with the tension lever 38 via a start spring 39. The control lever 34 is rotated about the support shaft 37 together with the tension lever 38 by bending the start spring 39 except at the time of starting. The lower end of the control rail lever 34 is engaged with the spill ring 33. When the control rail lever 34 is rotated in the left rotation direction in FIG. 5, the spill ring 33 moves to the right and the fuel injection amount increases. On the contrary, when it rotates in the clockwise direction in the figure, the spill ring 33 moves to the left and the fuel injection amount decreases.
[0036]
An adjusting lever 40 that applies operating force to the tension lever 38 is rotatably attached to the pump housing 12 via a shaft 41. An eccentric pin 42 is attached to one end of the shaft 41 protruding into the pump chamber 16. A control spring that pulls the tension lever 38 in the left direction in FIG. 5 is between the eccentric pin 42 and the tension lever 38. 43 is interposed. The tension of the control spring 43 increases when the adjusting lever 40 is rotated to the increase side of the fuel injection amount, and decreases when the adjustment lever 40 is rotated to the decrease side.
[0037]
Moreover, the control rail lever 34 receives the action of the governor 4 using centrifugal force. The governor 4 includes a governor shaft 45 fixed to the pump housing 12 so as to protrude into the pump chamber 16, a governor sleeve 46 slidably fitted on the outer periphery of the governor shaft 45, and a flyweight 47. Is the main component.
[0038]
The governor sleeve 46 has one end abutting against the control lever 34 and the other end abutting against the flyweight 47 via a washer 48. The governor sleeve 46 advances in the axial direction in conjunction with the opening operation of the flyweight 47 (see FIG. 5). Move in the right direction) and move backward in the axial direction (moving to the left in FIG. 5) in conjunction with the closing operation of the flyweight 47.
[0039]
The flyweight 47 is rotated by a driven gear 49 that is driven by a drive gear 5 that rotates integrally with the drive shaft 2, and is opened and closed by the centrifugal force of the rotation.
[0040]
The rotational positions of the control lever 34 and the tension lever 38 are determined by the balance between the control spring 43 and the pressing force of the governor sleeve 46 by the flyweight 47. As a result, the axial position of the spill ring 33 on the plunger 10 is determined, and the fuel injection amount is adjusted.
[0041]
For example, in a state in which the tension of the control spring 43 is kept constant, when the rotational speed of the drive shaft 2 increases, the flyweight 47 is opened by centrifugal force to advance the governor sleeve 46, and the control lever 34 is moved to the control spring 43. Against this, it is rotated in the clockwise direction in FIG. As a result, the spill ring 33 moves to the left in the figure, and the fuel injection amount decreases. vice versa,
When the rotational speed of the drive shaft 2 decreases, the centrifugal force acting on the flyweight 47 is weakened, and the control spring 43 rotates the control lever 34 in the counterclockwise direction of FIG. As a result, the spill ring 33 moves to the right in the figure, and the fuel injection amount increases.
[0042]
On the other hand, in the case where the rotational speed of the drive shaft 2 is constant, when the adjusting lever 40 is turned to the fuel injection amount increasing side, the tension of the control spring 43 increases, so that the control lever 34 is shown in FIG. The spill ring 33 moves to the right in the figure by rotating in the left rotation direction, and the fuel injection amount increases. At this time, the governor sleeve 46 is retracted as the control lever 34 rotates, and the flyweight 47 is closed accordingly. On the other hand, when the adjusting lever 40 is turned to the fuel injection amount decreasing side, the tension of the control spring 43 decreases, and the pressing force of the governor sleeve 46 against the control lever 34 becomes relatively large. As a result, the control lever 34 is rotated in the right rotation direction in FIG.
[0043]
A timer mechanism 24 for adjusting the fuel injection timing to the advance side or retard side by the pressure in the pump chamber 16 is provided below the pump housing 12. The timer mechanism 24 changes the rotation position of the roller ring 7 with respect to the rotation direction of the drive shaft 2, thereby changing the timing when the cam crest face 6 a rides on and off the cam roller 8, that is, when the plunger 10 is reciprocated. To change.
[0044]
As shown in FIG. 1, the timer mechanism 24 includes a timer piston 51 and is slidably inserted into and supported by a sliding hole 12 a formed in the pump housing 12 in a direction substantially orthogonal to the drive shaft 2. ing. The timer piston 51 is connected to the roller ring 7 via a slide pin 52. The timer piston 51 divides the inside of the sliding hole 12 a into a high pressure chamber (hereinafter, timer high pressure chamber) 54 and a low pressure chamber (hereinafter, timer low pressure chamber) 25. The timer pressure chamber 54 is partitioned by the timer piston 51, the sliding hole 12a, and the high-pressure timer cover 56. The timer low pressure chamber 25 is defined by a timer piston 51, a sliding hole 12a, and a low pressure side timer cover 57.
[0045]
In the timer piston 51, as shown in FIG. 1, a high pressure side orifice 53, a servo valve 60, an inflow passage 63, and a fuel passage 62 are provided. The high pressure side orifice 53 guides the fuel in the pump chamber 16 to the timer high pressure chamber 54. The servo valve 60 is slidably supported in a servo valve insertion hole 61a disposed in the timer piston 51 in the axial direction. The servo valve insertion hole 61a communicates with the fuel passage 62, and the fuel passage 62 opens into the servo valve insertion hole 61a. The servo valve insertion hole 61 a may be formed in the timer piston 51 or may be formed in the bush 61 inserted between the servo valve 60 and the timer piston 51.
[0046]
Hereinafter, in this embodiment, it is assumed that a servo valve insertion hole 61 a is formed in the bush 61 as shown in FIGS. 1 and 2. The bush 61 constitutes a part of the timer piston 51. As shown in FIG. 2, a substantially annular groove 61b extending in the circumferential direction is formed on the outer periphery of the bush 61, and a communication hole 61c penetrating the inner and outer surfaces is provided. The substantially annular groove 61b and the communication hole 61c constitute a part of the fuel passage 62, and the communication hole 61 forms an opening in which the fuel passage 62 opens on the inner peripheral surface of the servo valve insertion hole 61a. . Furthermore, a plurality of communication holes 61c are provided, and the communication holes 61c are arranged in a direction in which the acting force on the servo valve 60 due to the fuel flowing into the servo valve insertion holes 61a from the plurality of communication holes 61c cancels each other. preferable. The slidability of the servo valve 60 supported by the servo valve insertion hole 61a is improved, and a ripple effect such as preventing local wear due to sliding between the servo valve 60 and the servo valve insertion hole 61a is obtained.
[0047]
The inflow passage 63 is configured to guide the fuel in the pump chamber 16 to one end 60 a of the servo valve 60. A servo valve spring 64 is biased to the other end 60b against the fuel pressure in the pump chamber 16 acting on the one end 60a. The servo valve 60 includes a discharge passage 65 having one end opened on the outer peripheral surface of the servo valve 60 facing the servo valve insertion hole 61a and the other end opened in the timer low pressure chamber 25. The discharge passage 65 can be communicated with or cut off from the communication hole 61 c of the fuel passage 62 according to the axial movement of the servo valve 60. With such a configuration, the servo valve 60 receives the fuel pressure of the pump chamber 16 guided through the inflow passage 63 at one end 60a, and the servo valve spring 64 facing the fuel pressure is biased at the other end 60b. Therefore, the position of the servo valve 60 on the servo valve insertion hole 61a is moved in accordance with the fuel pressure change in the pump chamber 16. As a result, the timer piston 51 is switched to the position of the timer piston 51 for switching the communication passage between the discharge passage 65 and the communication hole 61c, that is, the communication between the fuel passage 65 communicating with the high pressure chamber 54 and the discharge passage leading to the low pressure chamber 25. To control.
[0048]
The high pressure side timer cover 56 defines the most retarded position of the timer piston 51. As shown in FIG. 1, the high-pressure side timer cover 56 includes a locking portion 56a, a step portion, and a flange portion 56c. Note that a sealing member 59 (hereinafter referred to as an O-ring) 59 such as an O-ring is inserted between the flange portion 56c and the end portion side of the sliding hole 12a in order to ensure oil tightness to the outside ( (See FIG. 1).
[0049]
As shown in FIG. 1, the locking portion 56 a is disposed so as to be able to contact the high pressure chamber side end surface 51 a of the timer piston 51, and regulates the most retarded position of the timer piston 51. The locking portion 56a extends into the sliding hole 12a. Thereby, the wall thickness of the high-pressure side timer cover 56 is increased. The locking portion 56a is thicker than at least the flange portion 56c.
[0050]
As shown in FIG. 1, the stepped portion 56b is inside the locking portion 56a. The step portion 56b is formed inside the locking portion 56a so as to extend in a direction away from the timer piston 51 (specifically, the high pressure chamber side end surface 51a). The shape of the stepped portion 56b is formed in a bottomed hole as shown in FIG. The shape of the locking portion 56a is substantially annular. That is, the locking portion 56a includes a substantially annular portion having a predetermined contact width W1 (see FIG. 2).
[0051]
The fuel space having a predetermined volume defined by the high pressure chamber side end face 51 a and the stepped portion 56 constitutes a part of the fuel space in the timer high pressure chamber 54. Even when the timer piston 51 is in the most retarded state, a fuel space having a predetermined volume can be obtained as the fuel space of the high-pressure chamber 54. Therefore, even when the timer piston 51 is in the most retarded state, a predetermined volume of fuel can be secured in the high pressure chamber 54.
[0052]
As shown in FIG. 1, an outer spring 55 that urges the timer piston 51 toward the high pressure side cover 56 is provided in the timer low pressure chamber.
[0053]
The fuel injection device 1 is provided with a load timer mechanism using the timer mechanism 24 and having a reverse advance characteristic that retards when the load of the internal combustion engine is large and advances when the load is small. .
[0054]
As shown in FIG. 3, the load timer mechanism is formed inside the governor shaft 45, an escape passage 76 having one end opened in the outer peripheral surface of the governor shaft 45 and the other end communicating with the low pressure side of the fuel, and a governor sleeve. And a through hole 77 that penetrates the inner and outer surfaces of the fitting portion of the governor shaft 45. The escape passage 76 includes a lateral hole 78 formed substantially at the center of the governor shaft 45, a longitudinal hole 79 that intersects the lateral hole 78 and extends in the radial direction of the governor shaft 45, and an opening of the longitudinal hole 79 is a bottom surface. It is comprised from the annular groove 80 opened in this. The right end of the horizontal hole 78 in FIG. 3 is sealed with a stopper (not shown). Further, the proximal end side of the lateral hole 78 is connected to the introduction port 23 via a low pressure port 82 (see FIG. 5) formed in the pump huffing 12. The through hole 77 is formed in a fitting portion with the governor shaft 45, and has a port 83 that penetrates the governor sleeve 46, and an annular groove 84 that is formed on the inner peripheral surface of the governor sleeve 46 and that the port 83 opens to the bottom surface. It consists of and.
[0055]
As shown in FIG. 3, the positional relationship between the escape passage 76 and the through hole 77 is such that the escape passage 76 and the through hole 77 are blocked when the governor sleeve 46 moves forward, and the escape passage 76 and the through hole 77 communicate with each other when the governor sleeve 46 moves backward. Are arranged to be.
[0056]
Here, the timer mechanism 24 and the load timer mechanism constitute a fuel injection timing control device that adjusts the fuel injection timing of the fuel injection device 1.
[0057]
The operation of the fuel injection device 1 having the above-described configuration will be described. Here, the operation of the timer mechanism and the load timer mechanism according to the present invention will be mainly described. When the internal combustion engine is driven, the drive shaft 2 and the feed pump 3 rotate in synchronization with the rotation of the internal combustion engine. Then, for example, the cam plate 6 is lifted down in the left direction in FIG. 5 via the cam roller 8 disposed on the roller ring 7. When the cam plate 6 ascends along the cam nose face 6a again via the cam roller 8, it is lifted up to the right in FIG. 5 with the rotation of the plunger 10, and the fuel in the plunger high pressure chamber 14 is pressurized. . As a result, the fuel pumped up from the fuel tank by the rotation of the feed pump 3 is pumped to the fuel injection nozzle of each cylinder through the pump chamber 16, the plunger high pressure chamber 14, the discharge port, and the delivery valve 20.
[0058]
In this way, the lift-down and lift-up of the cam plate 6 repeats the operation of the cam roller 8 on and off the cam crest face 6a, and the driving reaction force F at the end of the high-pressure fuel injection to the internal combustion engine is shown in FIG. Thus, the timer piston 51 acts from the cam plate 6 through the cam roller 8, the roller ring 7, and the slide pin 52. As a result, the timer high pressure chamber 54 is pressed by the driving reaction force F by the high pressure chamber side end surface 51 a of the timer piston 51. The driving reaction force F is obtained by dividing the driving torque reaction force acting on the roller ring 7 by the center distance of the timer piston 51 from the roller ring 7.
[0059]
In the load timer mechanism, as shown in FIG. 3, the positional relationship between the escape passage 76 and the through hole 77 is such that the escape passage 76 and the through hole 77 are blocked when the governor sleeve 46 moves forward, and the escape passage 76 and the through hole are moved backward. 77, the timer piston 51 is retarded as the load of the internal combustion engine increases (see FIG. 4A).
[0060]
Here, when the load is high, the fuel pressure in the pump chamber 16 is lowered by the operation of the load timer mechanism. The fuel in the pump chamber 16 is guided to the timer high pressure chamber 54 through the high pressure side orifice 53. On the other hand, the fuel in the timer high-pressure chamber 54 is discharged to the timer low-pressure chamber 25 through the fuel passage 62 and the discharge passage 65 by the communication and cutoff operation of the servo valve 60. For this reason, the fuel pressure in the timer high pressure chamber 54 does not increase, and the timer piston 51 may come into contact with the high pressure side timer cover 56 due to the urging force of the outer spring 55.
[0061]
When the driving reaction force F is applied to the timer piston 51, the timer piston 51 (specifically, the high-pressure chamber side end surface 51a) presses the high-pressure side timer cover 56 via the locking portion 56a and is driven to the high-pressure side timer cover 56. Reaction force F acts. As a result, the high-pressure side timer cover 56 is distorted and deformed by the driving reaction force F generated by the high-pressure fuel injection, and the volume of the timer high-pressure chamber 54 is increased. As the volume increases, the fuel pressure in the timer high pressure chamber 54 tends to decrease.
[0062]
Even when the timer piston 51 is in the most retarded state, a predetermined volume of fuel is secured in the high pressure chamber by the stepped portion 56b formed in the high pressure side timer cover 56. Compared to the volume of the high-pressure chamber in the most retarded angle state of the conventional timer piston 51, the volume is increased by a predetermined volume.
[0063]
Thereby, even if deposition in the high-pressure chamber 54 increases due to deformation of the high-pressure timer cover 56, the volume change rate can be reduced. By forming the predetermined volume by the step portion 56b to be large to some extent, the volume change rate becomes small or small. Therefore, since the volume change rate can be reduced or made small, the generation of negative pressure can be prevented or suppressed.
[0064]
Further, when the high-pressure timer cover 56 is deformed, even if the high-pressure chamber 54 and the low-pressure chamber 25 communicate with each other via the fuel passage 62 by the servo valve 60, the fuel in the high-pressure chamber 54 has at least a predetermined volume. It is possible to avoid that all the fuel in the chamber 54 flows out immediately. As a result, it is possible to prevent the negative pressure from being induced by the communication operation of the servo valve 60.
[0065]
As a result, it is possible to prevent the formation of a cavity caused by the generation of negative pressure, so that the occurrence of cavitation erosion on the high pressure chamber side end surface 51a of the timer piston 51 can be prevented.
[0066]
In the present embodiment described above, since the locking portion 56b has a substantially annular portion, when the high pressure chamber side end surface 51a of the timer piston 51 contacts the locking portion 56b, a stable contact surface is ensured. Is possible. Regardless of the shape of the stepped portion 56b formed in the locking portion 56a, the locking portion 56a is not impaired as a contact surface that can be stably contacted.
[0067]
In the present embodiment described above, it is preferable that the outer periphery of the locking portion 56a and the sliding hole 12a are loosely fitted. Thereby, the clearance gap between the outer periphery of the latching | locking part 56a and the sliding hole 12a is narrowed so that it may fit. As a result, the narrowed gap prevents the fuel pressure in the high pressure chamber from being directly transmitted to the O-ring 59 inserted between the end portion side of the sliding hole 12a and the flange portion 56c. The Therefore, it is possible to protect the O-ring 59 from sudden pressure fluctuations of the fuel in the high pressure chamber 54 due to the influence of the driving torque reaction force. Note that a sudden pressure fluctuation of the fuel in the high pressure chamber 54 occurs when the driving torque reaction force generated at each fuel injection is applied to and released from the timer piston 51 even if no negative pressure (cavity) is generated. Because. The rapid pressure fluctuation of the fuel in the high-pressure chamber 54 is smaller than the impact energy generated when the cavity is collapsed, and does not affect anything other than rubber such as an O-ring or a resin member.
[0068]
(Second and third embodiments)
A second embodiment will be described with reference to FIG. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated. 6A and 6B are views showing the high-pressure side timer cover according to the present embodiment, in which FIG. 6A is a cross-sectional view, and FIG. 6B is a plan view as viewed from A of FIG.
[0069]
In the second embodiment, in the high-pressure timer cover 156, the stepped portion 156b formed inside the locking portion 56a described in the first embodiment is a substantially annular groove. As shown in FIG. 6B, the locking portion 56a has a second locking portion 156a on the center side of the locking portion 56a, that is, on the inner side of the stepped portion 156b. Even if it does in this way, the effect similar to 1st Embodiment can be acquired.
[0070]
Furthermore, since the locking part 56a has the second locking part 156a, the contact area with the high-pressure chamber side end surface 51a can be increased. Therefore, for example, when it is desired to reduce the flow loss of the fuel flow around the opening on the high pressure chamber side end surface 51a side of the fuel passage 62, the contact area between the locking portion 56 and the high pressure chamber side end surface 51a is the same. Therefore, the contact width at the substantially annular portion of the locking portion 56a can be reduced from W1 to W2 (W2 <W1). In this case, there is almost no difference in the ease of fuel flow in the high pressure chamber 54. The effect of preventing the generation of local negative pressure due to the flow loss is also obtained. For example, when the high-pressure timer cover 56 is deformed, even if the high-pressure chamber 54 and the low-pressure chamber 25 are communicated via the fuel passage 62 by the servo valve 60, local negative pressure is generated due to the loss of flow. There is no.
[0071]
A third embodiment will be described with reference to FIG. 7A and 7B are views showing the high-pressure side timer cover according to the present embodiment, in which FIG. 7A is a cross-sectional view, and FIG. 7B is a plan view as viewed from A of FIG.
[0072]
In the third embodiment, as shown in FIG. 7B, in the stepped portion 256b of the high-pressure side timer cover 256, the shape of the opening of the bottomed hole described in the first embodiment is made substantially semicircular. May be. The second locking portion 256a constituting the locking portion 56a faces the high-pressure side orifice 53 with a small throttle, and the bottom surface of the stepped portion 256b faces the fuel passage 62 having a relatively large opening area. As a result, the ease of fuel flow in the high-pressure chamber 54 becomes substantially uniform. Even if it does in this way, the effect similar to 2nd Embodiment can be acquired.
[0073]
In the present embodiment described above, by adopting the shape of the stepped portions 56a, 156b, and 256b of the first, second, and third embodiments, a high-pressure timer can be obtained by a manufacturing method such as cutting or forging. The covers 56, 156, 256 can be easily formed. Therefore, the fuel injection device 1 capable of preventing the occurrence of cavitation erosion can be provided at a low cost.
[0074]
Furthermore, as means for securing a predetermined volume in the fuel space in the high pressure chamber 54 in the most retarded state of the timer piston 51, the high pressure side timer covers 56, 156 are all used in the first, second, and third embodiments. Since the step portions 56a, 156b, and 256b are provided in 256, it is easy to ensure a large predetermined volume.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a timer mechanism according to a fuel injection device of a first embodiment of the present invention.
2A and 2B are diagrams showing a high-pressure timer cover in FIG. 1, in which FIG. 2A is a cross-sectional view, and FIG. 2B is a plan view as viewed from A of FIG.
FIG. 3 is a longitudinal sectional view showing a load timer mechanism according to the first embodiment.
4A and 4B are graphs showing an advance angle characteristic by a load timer mechanism, in which FIG. 4A is a reverse advance angle characteristic that retards as the load increases, and FIG. 4B is a comparison that retards as the load decreases. It is a graph which shows the advance angle characteristic of an example.
FIG. 5 is a longitudinal sectional view showing the fuel injection device according to the first embodiment of the present invention.
6A and 6B are views showing a high-pressure side timer cover according to a second embodiment, in which FIG. 6A is a cross-sectional view, and FIG. 6B is a plan view seen from A in FIG. .
7A and 7B are views showing a high-pressure side timer cover according to a third embodiment, in which FIG. 7A is a cross-sectional view, and FIG. 7B is a plan view seen from A in FIG. 7A. .
[Explanation of symbols]
1 Fuel injector
2 Drive shaft
3 Feed pump
4 Governor
6 Cam plate
7 Roller ring
8 Cam rollers
10 Plunger
12 Housing
12a Sliding hole
14 Plunger high pressure chamber
24 Timer mechanism
25 Timer Low Pressure Chamber (Low Pressure Chamber)
45 Governor shaft
46 Governor Sleeve
47 Flyweight
51 Timer piston
53 High-pressure side orifice
54 Timer High Pressure Chamber (High Pressure Chamber)
55 Outer Spring
56 High-pressure timer cover
56a Locking part
56b Stepped part
56c Flange
59 O-ring (seal member)
60 servo valves
61a Servo valve insertion hole
61b substantially annular groove (part of fuel passage)
61c Communication hole (part of fuel passage)
62 Fuel passage
63 Inflow passage
64 Servo valve spring
65 discharge passage
76 Relief passage (part of load timer mechanism)
77 Through hole (part of load timer mechanism)

Claims (4)

A feed pump for supplying fuel into the pump chamber;
A governor shaft disposed in the pump chamber and a slidably fitted outer periphery of the governor shaft, advance in the axial direction in conjunction with the opening operation of the flyweight, and in conjunction with the closing operation of the flyweight. A governor having a governor sleeve retracting axially;
A fuel injection device comprising a timer mechanism for advancing the fuel injection timing when the fuel in the pump chamber is at a high pressure and for retarding the fuel injection timing when the fuel is at a low pressure;
An escape passage formed in the governor shaft, having one end opened in the outer peripheral surface of the governor shaft and the other end communicating with the low pressure side of the fuel, and a fitting portion formed in the governor sleeve and the governor shaft And has a through hole that is cut off from the escape passage when the governor sleeve advances, and communicates with the escape passage when retreating,
In the timer mechanism, a timer piston engaged with a roller ring capable of adjusting fuel injection timing and a sliding hole for slidably supporting the timer piston are divided into two pressure chambers. Is a high pressure chamber that receives the driving torque reaction force acting on the roller ring via the timer piston, and the other is a low pressure chamber that communicates with the low pressure side of the fuel. A high-pressure timer cover having a locking portion for regulating the position; a servo valve insertion hole formed in the timer piston and opening into the low-pressure chamber; an inflow passage through which fuel in the pump chamber is supplied; and the high-pressure chamber A fuel passage that opens into the servo valve insertion hole, and a servo valve that is slidable in the servo valve insertion hole,
The servo valve receives the pressure of the fuel in the pump chamber guided from the inflow passage at one end thereof, and the servo valve spring is biased against the fuel pressure at the other end to change the pressure of the fuel in the pump chamber. In accordance with the communication between the fuel passage and the low-pressure chamber,
The high pressure side timer cover is provided with a stepped portion extending in a direction away from the timer piston at the locking portion,
And the locking part extends into the sliding hole, and the outer periphery of the locking part and the sliding hole are loosely fitted,
The high-pressure side timer cover is a separate member from the housing in which the sliding hole is formed, and further includes a flange portion for closing the sliding hole,
A fuel injection device , wherein a seal member is inserted between the flange portion and the housing .   The fuel injection device according to claim 1, wherein the stepped portion is a bottomed hole formed inside the locking portion.   2. The fuel injection device according to claim 1, wherein the stepped portion is a substantially annular groove formed inside the locking portion. The fuel injection device according to any one of claims 1 to 3, wherein the locking portion includes a substantially annular portion .

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