JP2007127002A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of making compatible the holding of a high fuel gallery pressure during the high speed rotation of a pump with the holding of a low fuel gallery pressure during the low speed rotation of the pump, reducing cavitation erosion, and preventing hunching and engine stall. <P>SOLUTION: A pressure control valve 20 controlling a fuel feed pressure is installed on the discharge side of a fuel injection pump 11 of a diesel engine. The pressure control valve 20 comprises a pressure control valve body (holder) 21, a piston 22 contained in the pressure control valve body 21, and a spring 23 biasing the piston 22. A relief mechanism is formed at a piston stroke initial portion between the pressure control valve body 21 and the piston 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technology of a fuel injection pump. More specifically, the present invention relates to a technology of a fuel injection device provided with a relief mechanism in a piston mechanism of a pressure regulating valve that adjusts a fuel supply pressure.

  Conventionally, a diesel engine has been provided with a fuel injection device for injecting fuel into a combustion chamber. In the fuel injection device, a pressure regulating valve is provided between a high-pressure side fuel gallery and a low-pressure side fuel tank. 100 is interposed. For example, as shown in FIG. 12, the pressure regulating valve 100 is slidably fitted into a pressure regulating valve main body (holder) 101 in which a fitting hole 101a is formed, and a fitting hole 101a of the pressure regulating valve main body 101. The piston 102 includes a spring 103 that urges the piston 102 to one side in the sliding direction.

  The pressure regulating valve main body 101 is formed with a main body hole 101 b that communicates the inside and the outside of the fitting hole 101 a, and the main body hole 101 b is opened and closed by sliding of the piston 102. One end side 101c of the fitting hole 101a is connected to a fuel gallery which is a high pressure side circuit of the fuel injection pump, and the main body hole 101b is connected to a fuel tank which is a low pressure side circuit. When the main body hole 101b is closed by the piston 102, the one end side 101c of the fitting hole 101a and the main body hole 101b are divided, and when the main body hole 101b is open, the one end side 101c of the fitting hole 101a. And the body hole 101b communicate with each other.

  The opening and closing of the main body hole 101b by the piston 102 is performed by a sliding operation of the piston 102, and the piston 102 is attached in the direction in which the main body hole 101b is closed by the spring 103 until the pressure in the fuel gallery exceeds a predetermined pressure. It is energized. On the contrary, when the pressure in the fuel gallery exceeds a predetermined pressure, the piston 102 slides against the urging force of the spring 103 by the pressure, and the main body hole 101b opens to release the pressure in the fuel gallery. The internal pressure in the fuel gallery is adjusted.

  The space in which the spring 103 is accommodated in the fitting hole 101a of the pressure regulating valve main body 101 is configured in the spring accommodating chamber 101d, and the piston 102 has one end side of the spring accommodating chamber 101d and the fitting hole 101a. An air vent hole 102a communicating with 101c is formed. The air vent hole 102a has a small diameter, and is configured to discharge air bubbles generated in the fuel gallery from the air vent hole 102a to the low pressure side. Further, the fuel oil in the fuel gallery gradually leaks out to the low pressure side from the air vent hole 102a at all times. The pressure regulating valve main body 101 is formed with a communication hole 101e that communicates the inside of the spring storage chamber 101d with the low pressure side.

  By the way, in the fuel injection pump having the pressure regulating valve described above, cavitation erosion that occurs in the pump conventionally (damage of the material surface due to the impact force generated when the bubbles generated in the fluid flowing at high speed collapse) Measures to prevent hunting and engine stall at the time of low pump rotation have been studied at the same time as reducing pumping and extending pump life. Here, in order to reduce the occurrence of cavitation and erosion, it is desirable to set the set pressure that the pressure regulating valve 100 opens as high as possible and maintain the fuel gallery pressure as high as possible, while preventing hunting and engine stall. On the other hand, since it is desirable to keep the fuel gallery pressure low, it is necessary to satisfy both requirements simultaneously.

As a countermeasure for this, a technology is known in which a pressure relief fitting hole is provided in the piston to simultaneously satisfy the high pressure holding of the fuel gallery pressure during high pump rotation and the low pressure holding of the fuel gallery pressure during low pump rotation. It has become. In other words, the piston is closed at the time of low pump rotation, but the fuel gallery side (high pressure side) and the fuel tank side (low pressure side) are communicated with each other through the pressure relief fitting hole. As a result, the fuel gallery pressure can be maintained at a low pressure. Also, when the pump is rotating at high speed, the pressure relief fitting hole closes at the same time as the piston opens, so no pressure loss occurs and the set pressure can be set to a high pressure and the fuel gallery pressure can be maintained at a high pressure. Yes (see Patent Document 1).
JP 2003-65186 A

  As described above, there has been provided a technique for improving the conventional pressure regulating valve and simultaneously satisfying the reduction of cavitation erosion and the prevention of hunting and engine stalling, but problems associated with realization still remain. That is, in the invention shown in Patent Document 1, when the piston is closed, the pressure relief fitting hole is fully opened, and as the piston slides toward the spring housing chamber 101d, the pressure relief fitting hole is provided. And the piston opens the main body hole 101b, and at the same time, the requirements for completely closing the pressure relief fitting hole must be satisfied, and it is not easy to ensure the accuracy of processing and assembly. It also induces an increase in cost.

  Therefore, in the present invention, as a new technology for improving the conventional pressure regulating valve, the high pressure holding of the fuel gallery pressure at the time of high pump rotation and the low pressure holding of the fuel gallery pressure at the time of low pump rotation are satisfied at the same time.・ Provide technologies to reduce erosion and prevent hunting and engine stalls.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in the first aspect of the present invention, in the configuration in which the pressure regulating valve for adjusting the fuel supply pressure is provided on the discharge side of the fuel injection pump according to the diesel engine, the pressure regulating valve includes a holder, a piston housed in the holder, and the piston And a relief mechanism is provided at the initial part of the piston stroke between the holder and the piston.

  According to a second aspect of the present invention, the escape mechanism is formed by providing a stepped portion at the end of the piston.

  According to a third aspect of the present invention, the escape mechanism is formed by providing an orifice in the holder.

  As effects of the present invention, the following effects can be obtained.

  According to claim 1, in the pressure regulating valve provided on the discharge side of the fuel injection pump, a relief mechanism is provided in the initial part of the piston stroke between the holder and the piston, so that the inside of the fuel gallery in the initial sliding region of the piston is provided. The fuel leaks to the low-pressure side via the escape mechanism, and the fuel supply pressure (feed pressure) is reduced. Therefore, the followability of the plunger is improved, and the fuel injection pump has a low rotation speed. Hunting and engine stall during operation can be prevented. Also, during rated operation where the number of revolutions of the fuel injection pump is high, the pressure in the fuel gallery increases and the fuel supply pressure also rises, so the occurrence of cavitation and erosion is suppressed, and the pump itself has a long service life. Leads to

  According to a second aspect of the present invention, since the escape mechanism is formed by providing a stepped portion at the end of the piston, the escape mechanism can be configured with a simple configuration, and the fuel at low cost can be obtained at low cost. Supply pressure can be reduced.

  According to the third aspect of the present invention, by providing an escape mechanism by providing an orifice in the holder, the piston can be used as it is, and the escape mechanism can be configured with a simple configuration in which a hole is opened. Similarly, it is possible to reduce the fuel supply pressure during low rotation of the fuel injection pump at a low cost.

Next, embodiments of the invention will be described.
1 is a front view showing an arrangement portion of a pressure regulating valve of a pump body according to an embodiment of the present invention, FIG. 2 is a plan view showing the arrangement portion of the pressure regulating valve, and FIG. 3 is a pressure regulating valve of the present invention. It is side surface sectional drawing which shows the fuel-injection pump arrange | positioned. FIG. 4 is a side sectional view showing a state where the piston is closed in the pressure regulating valve according to the first embodiment of the present invention, and FIG. 5 is a view showing a state where the piston is opened in the pressure regulating valve according to the first embodiment of the present invention. FIG. 6 is a side sectional view, and FIG. 6 is a perspective view of the piston of the pressure regulating valve according to one embodiment of the present invention as viewed obliquely from above. FIG. 7 is a side sectional view showing a state in which the piston is closed in the pressure regulating valve according to the second embodiment of the present invention, and FIG. 8 shows a state in which the piston is opened in the pressure regulating valve according to the second embodiment of the present invention. FIG. 9 is a side sectional view showing the holder of the pressure regulating valve according to the second embodiment of the present invention. FIG. 10 is a diagram showing a difference in fuel supply pressure in the low speed region of the fuel injection pump rotation speed when the conventional pressure regulating valve is used and when the pressure regulating valve according to the present invention is used. FIG. 11 is a view showing the relationship between the opening area of the pressure regulating valve and the sliding amount of the piston, and FIG. 12 is a side sectional view showing a state where the piston is closed according to a conventional pressure regulating valve.

  Example 1 of the present invention will be described below.

[overall structure]
As shown in FIGS. 1 and 2, the pressure regulating valve 20 of the present invention is arranged on the upper surface of the pump body 1 in parallel with a plurality of fuel injection pumps, and one end of the pressure regulating valve 20 is connected to the fuel gallery 8 inside the pump body 1. Communicate. As shown in FIG. 3, the fuel injection pump includes a pump chamber 3 formed in a plunger barrel 2 fitted in the pump body 1, and a pump chamber 3 in a delivery holder 4 attached to the upper portion of the plunger barrel 2. In the pump chamber 3, the plunger 6 reciprocates and slides, so that the fuel is pumped to the fuel injection valve via the delivery oil passage 5.

  In the plunger barrel 2, barrel ports 7 are formed in a direction perpendicular to the sliding direction of the plunger 6, and the barrel ports 7 are communicated with a fuel gallery 8 formed in the pump body 1. The pump body 1 is provided with a fuel intake passage (not shown) and a fuel discharge passage (not shown) for communicating the fuel gallery 8 with the outside, and fuel is supplied from the fuel intake passage to the fuel gallery 8 and the barrel port. 7 is supplied into the pump chamber 3 through the barrel port 7 and the fuel gallery 8 and is discharged from the fuel discharge passage to the fuel tank (not shown) side. A pressure regulating valve (not shown) is interposed between the fuel discharge passage communicating with the fuel gallery 8 and the fuel tank, and is attached to the pump body 1.

  The fuel is supplied to the fuel gallery 8 by a fuel supply pump (not shown) attached to the fuel injection pump, and the fuel supply pump changes the fuel discharge amount according to the engine speed. It is configured. That is, the discharge amount is small when the engine speed is low, and the discharge amount is large when the engine speed is high.

[Pressure control valve]
Next, the configuration of the pressure regulating valve 20 will be described (note that the pressure regulating valve 20 according to the first embodiment of the present invention is different from the conventional pressure regulating valve 100 with respect to a partial shape of the piston).
As shown in FIGS. 4 and 5, the pressure regulating valve 20 is slidably fitted into the pressure regulating valve main body 21 in which the fitting hole 21 a is formed in the shaft center portion, and the fitting hole 21 a of the pressure regulating valve main body 21. It comprises a piston 22 to be mounted and a spring 23 that biases the piston 22 to one side in the sliding direction.

  In the pressure regulating valve main body (holder) 21, a main body hole 21b that communicates the inside of the fitting hole 21a with the outside is opened in the longitudinal direction of the pressure regulating valve main body 21 in a direction perpendicular to the fitting hole 21a. Is opened and closed by sliding of the piston 22. One end of the fitting hole 21a of the pressure regulating valve main body 21 is closed by an adjusting screw 25 or a stopper, and a spring 23 is accommodated in the piston 22 and the closed space to form a spring accommodating chamber 21d. One end side 21c of the fitting hole 21a is connected to a fuel discharge passage communicating with the fuel gallery 8 which is a high-pressure side circuit of the fuel injection pump, and the main body hole 21b is a low-pressure side (excess return side) circuit. Connected to the fuel tank.

  As shown in FIG. 4, when the piston 22 is urged by the spring 23 and slides toward the one end 21c, the main body hole 21b is closed by the piston 22, and conversely, as shown in FIG. When the piston 22 slides toward the spring housing chamber 21d against the biasing force of the spring 23, the main body hole 21b is opened by the piston 22, and the one end side 21c of the fitting hole 21a and the main body hole 21b are directly connected. It is configured to communicate.

The opening and closing of the main body hole 21b by the piston 22 is performed by a sliding operation of the piston 22, and the piston 22 is moved in a direction in which the main body hole 21b is closed by the spring 23 until the pressure in the fuel gallery exceeds a predetermined pressure. Hold the energized state. On the contrary, when the pressure in the fuel gallery exceeds a predetermined pressure, the piston 22 slides against the urging force of the spring 23 by the pressure, and the main body hole 21b is opened to release the pressure in the fuel gallery. Thus, the pressure in the fuel gallery is adjusted so as not to exceed the pressure set by the spring 23. The urging force of the spring 23 that presses the piston 22 has a mechanism that can be freely adjusted by moving an adjustment screw 25 arranged opposite to the piston 22.
In the present invention, a relief mechanism is provided in the initial part of the piston stroke between the pressure regulating valve main body (holder) 21 and the piston 22. First, an embodiment in which a relief mechanism is provided on the piston will be described.

[piston]
The piston 22 has a shape in which a stepped portion 24 having a small outer diameter is provided on the fuel gallery side of the conventional piston 102, and its formation range (the length of the small diameter portion in the axial direction, that is, Dimension (a) shown in FIG. 4 is based on the insertion depth (dimension (b) shown in FIG. 4) in a state where the piston 22 inserted into the fitting hole 21a does not receive pressure from the fuel gallery side (when not acting). It is a slightly shallow area. And the minute latching | locking part (dimension C shown in FIG. 4) of piston 22 and the fitting hole 21a is utilized for position control at the time of piston 22 insertion. However, it is also possible to form a stepped portion by providing a groove or slit in the outer periphery of the piston 22 on the fuel gallery side within the range of dimension A.

  In the state where the piston 22 is slid to the one end side 21c (Stoke start end side) by the spring 23 (the state shown in FIG. 4), the body hole 21b is closed by the piston 22, but the air vent hole 22a is in communication. Therefore, bubbles and fuel oil generated in the fuel gallery gradually leak to the low pressure side.

  From this state, when the pressure in the fuel gallery rises and the piston 22 slides toward the spring accommodating chamber 21d side (stroke end side), the fuel immediately after the piston 22 is detached from the minute latching portion. The fuel oil in the gallery starts to leak from the stepped portion 24 of the piston 22 to the low pressure side. As the sliding distance of the piston 22 increases, the gap portion 21f in the stepped portion 24 also gradually increases.

  When the pressure in the fuel gallery further rises and one side end of the piston 22 completely disengages the insertion part with the fitting hole 21a, the opening cross-sectional area of the main body hole 21b begins to expand, and the communication between the fuel gallery and the low pressure side begins. Part area increases rapidly. Further, the piston 22 slides, and in the state shown in FIG. 5, the main body hole 21b is completely opened.

  As described above, in the sliding region of the piston 22, the mechanism for changing the amount of increase in the communication portion area between the fuel gallery and the low pressure portion between the region when the pressure in the fuel gallery is low and the region when the pressure is high. By providing, the fuel supply pressure in the low pressure region is reduced as compared with the conventional pressure regulating valve, and the fuel supply pressure in the high pressure region is maintained at a predetermined set pressure equivalent to the conventional pressure regulating valve. Is possible. The pressure regulating valve main body 21 of the pressure regulating valve 20 is formed with a communication hole 21e that communicates the inside of the spring storage chamber 21d with the low pressure side on the outside, and when the piston 22 slides toward the spring storage chamber 21d. The fuel in the spring storage chamber 21d is configured to escape to the low pressure side. This prevents the fuel in the spring storage chamber 21d from becoming a resistance against the sliding of the piston 22.

Next, a specific operation of the pressure regulating valve 20 during the fuel supply pump operation will be described.
In the pressure regulating valve 20 configured as described above, when the engine is stopped, the piston 22 slides toward the one end side 21c, and the body hole 21b is completely closed by the piston 22 (see FIG. 4). State shown.) In this state, the high pressure side and the low pressure side are communicated with each other only through the air vent hole 22a fitted in the piston (S1 shown in FIG. 11).

  Since the engine is started from this state and the discharge amount of the fuel supply pump of the engine increases as the engine speed increases, when the engine speed increases, the fuel gallery in the fuel injection pump The pressure of the piston 22 also rises, and the piston 22 slides toward the spring accommodating chamber 21d by the pressure. The gap 21f formed by the stepped portion 24 of the piston 22 gradually increases until the piston 22 completely removes the insertion portion with the fitting hole 21a, and the fuel gallery and the low pressure side are separated. Since the area of the opening that communicates is the sum of the air vent hole 22a and the gap 21f, the area gradually increases as a whole (S2 shown in FIG. 11).

  Thereafter, when the engine speed further increases and the discharge amount increases, the main body hole 21b starts to open, and the opening area increases with the sliding distance of the piston 22, so that the fuel gallery communicates with the low pressure side. Since the partial area is the sum of the air vent hole 22a, the gap portion 21f, and the main body hole 21b, the whole area is rapidly increased and the main body hole 21b is completely opened (the state shown in FIG. 5). Thus, the area of the opening that communicates the fuel gallery and the low-pressure side becomes the maximum value (S3 shown in FIG. 11).

  On the other hand, the conventional pressure regulating valve 100 shown in FIG. 12 has a very small opening area S until the piston 102 reaches a certain sliding amount (that is, until the pressure in the fuel gallery reaches a predetermined pressure). The area is only the area for the extraction hole 102a. When the sliding amount is exceeded, the main body hole 101b starts to open, and the opening area increases rapidly according to the sliding amount of the piston 102.

  As described above, in the conventional pressure regulating valve 100, when the engine speed is low, the opening area S is almost zero, so almost all the fuel pressure from the fuel supply pump is accumulated in the fuel gallery. As shown in FIG. 3, the pressure in the fuel gallery is almost the pressure P2 at the time of rated operation since the engine speed is the low speed N1 at the time of low idling.

  On the other hand, in the pressure regulating valve 20 of the present invention, even when the engine speed is low, the opening of the gap portion 21f can secure a certain opening area as a whole, so that part of the fuel pressure from the fuel supply pump The pressure escapes to the low pressure side through the hole 21b and the communication hole 21e, and the pressure in the fuel gallery is considerably lower than the pressure P2 at the low rotational speed N1 during low idling. . As the engine speed increases, the pressure in the fuel gallery increases accordingly. When the engine speed reaches the rated operation speed N2, the body hole 21b is fully opened, and the pressure in the fuel gallery is adjusted as described above. Like the pressure valve 100, P2 is obtained.

  Here, in order to reduce the occurrence of cavitation erosion in the fuel injection pump, it is desirable to increase the fuel gallery pressure, and in order to prevent hunting and engine stall, it is desirable to decrease the fuel gallery pressure. In the pressure regulating valve 20 of the present invention, the pressure of the fuel gallery is reduced at the time of low rotation with a small discharge amount of the fuel supply pump, and the pressure of the fuel gallery is increased at the time of high rotation with a large discharge amount of the fuel supply pump. Can do. Therefore, in the fuel injection pump provided with the pressure regulating valve 20, the pressure in the fuel gallery can be set high during high load and high rotation, and the occurrence of cavitation and erosion can be suppressed, and the fuel gallery pressure can be reduced during rotation. By setting it, it becomes possible to prevent hunting and engine stall, and it is possible to realize both reduction of cavitation and erosion and prevention of hunting and engine stall.

  Further, the gap 21f for allowing the fuel in the high-pressure side fuel gallery to flow out to the low-pressure side fuel tank communicates only with the main body hole 21b with respect to the low-pressure side, and is not provided in the spring housing chamber 21d. The fuel pressure from the fuel gallery does not enter the spring housing chamber 21d and interfere with the sliding operation of the piston 22, so that the pressure of the fuel gallery can be lowered at the time of low rotation.

Next, Example 2 of the present invention will be described below.
In the second embodiment, the piston 32 has the same shape as the conventional piston 102 as compared with the first embodiment, and a fitting hole 31f is added to a part of the pressure regulating valve main body (holder) 31. Depending on the content.

[Pressure control valve]
That is, as shown in FIGS. 7 and 8, the pressure regulating valve 30 is slidably fitted into the pressure regulating valve main body 31 in which the fitting hole 31 a is formed and the fitting hole 31 a of the pressure regulating valve main body 31. And a spring 33 that urges the piston 32 to one side in the sliding direction, and is urged to the one end side 31c by the spring 33 so that the piston 32 is in the fuel gallery. Due to the rise in pressure, the piston 32 slides toward the spring housing chamber 31d against the urging force of the spring 33 and has a function of opening the body hole 31b. Then, in the fitting hole 31a of the pressure regulating valve main body 31, the fitting hole 31f is provided on the sliding side of the set length from the tip of the piston 32 in a state where the pressure in the fuel gallery is not applied. The pressure of the fuel gallery during rotation can be lowered. Hereinafter, the details will be described focusing on the pressure regulating valve main body 31.

[Pressure adjustment valve body]
The pressure regulating valve main body (holder) 31 has a structure in which a fitting hole 31 f is provided in a part of the conventional pressure regulating valve main body 101. That is, in FIG. 8, a fitting hole 31a passing through the pressure regulating valve body 31 in the axial direction, a body hole 31b fitted perpendicularly to the fitting hole, and in parallel with the body hole 31b, the pressure regulating valve In the structure of the conventional pressure regulating valve main body 101 having a communication hole 31e that communicates the inside of the main body 31 with the outside, the fitting that communicates the inside and outside of the pressure regulating valve main body 31 with the piston 32 insertion portion of the fitting hole 31a. A hole 31f is provided in the initial part of the piston stroke. That is, the fitting hole 31f is disposed with a hole having a smaller diameter than the main body hole 31b between the main body hole 31b and the tip of the piston 32 in a state where the piston 32 does not slide against the spring 33. ing. This fitting hole 31f has a structure in which the fuel oil in the fuel gallery is gradually leaked to the low pressure side at the initial sliding of the piston 22 to prevent the pressure in the fuel gallery from rapidly increasing.

Next, the operation of the pressure regulating valve 30 will be described.
In a state where the piston 32 is slid to one end side (the stroke start end side) by the spring 33 (the state shown in FIG. 7), the body hole 31b is closed by the piston 32, but the air vent hole 32a is in communication. Therefore, bubbles and fuel oil generated in the fuel gallery gradually leak to the low pressure side.

  From this state, when the pressure in the fuel gallery rises and the piston 32 starts to slide to the other end side (stroke end side) against the biasing force of the spring 33 due to the pressure, the fuel oil in the fuel gallery Begins to leak to the low-pressure side through the fitting hole 31f via a gap formed at the tip of the fitting hole 31a and the piston 32. As the sliding distance of the piston 32 increases, the gap formed at the fitting hole 31a and the tip of the piston 32 also gradually increases, increasing the amount of fuel oil leaking to the low pressure side, but the fitting hole 31f. Since the opening cross-sectional area of the fuel oil is constant, the increase stops when the amount of fuel oil leakage exceeds a certain amount.

  When the pressure in the fuel gallery further increases and one end of the piston 32 completely disengages the insertion portion with the fitting hole 31a, the opening cross-sectional area of the main body hole 31b begins to expand, and the communication between the fuel gallery and the low pressure side begins. Part area increases rapidly. Further, the piston 32 slides, and in the state shown in FIG. 8, the main body hole 31b is completely opened.

  As described above, in the sliding region of the piston 32, as in the first embodiment, in the region where the pressure in the fuel gallery is low and high, the mechanism for changing the amount of increase in the communication portion area between the fuel gallery and the low pressure portion is changed. The fuel supply pressure in the low pressure region is reduced as compared with the conventional pressure regulating valve, and the fuel supply pressure in the high pressure region is maintained at a predetermined set pressure, equivalent to the conventional pressure regulating valve. Make it possible. As a result, the fuel gallery pressure can be set low to prevent hunting and engine stall at low revolutions when the discharge rate of the fuel supply pump is low, and at the same time, the pressure in the fuel gallery can be prevented at high revolutions with a large discharge rate. Can be set high to suppress the occurrence of cavitation erosion.

The front view which shows the arrangement | positioning part of the pressure regulation valve of the pump main body based on one Example of this invention. Similarly, the top view which shows the arrangement | positioning part of a pressure regulation valve. Side surface sectional drawing which shows the pressure regulation valve of this invention, and the fuel injection pump arrange | positioned. Side surface sectional drawing which shows the state which the piston closed of the pressure regulation valve which concerns on 1st Example of this invention. Side surface sectional drawing which shows the state which the piston opened of the pressure regulation valve which concerns on 1st Example of this invention. The perspective view which looked at the piston of the pressure regulation valve based on one Example of this invention from diagonally upward. Side surface sectional drawing which shows the state which the piston closed of the pressure regulation valve which concerns on 2nd Example of this invention. Side surface sectional drawing which shows the state which the piston opened of the pressure regulation valve which concerns on 2nd Example of this invention. Side surface sectional drawing which showed the holder of the pressure regulation valve which concerns on 2nd Example of this invention. The figure which shows the difference of the fuel supply pressure in the low speed area | region of the fuel-injection pump rotation speed at the time of using the conventional pressure regulation valve, and the case where the pressure regulation valve which concerns on this invention is used. The figure which shows the relationship between the opening area of a pressure regulation valve, and the sliding amount of a piston. Side surface sectional drawing which shows the state which the piston related to the conventional pressure regulation valve closed.

Explanation of symbols

20 pressure regulating valve 21 pressure regulating valve body 22 piston 23 spring 24 stepped portion 25 adjusting screw 21a fitting hole 21b body hole 21c one end side of fitting hole 21a 21d spring accommodating chamber 21e communicating hole 21f gap

Claims (3)

  In a configuration in which a pressure regulating valve for adjusting a fuel supply pressure is provided on a discharge side of a fuel injection pump of a diesel engine, the pressure regulating valve is biased toward a holder, a piston housed in the holder, and a piston closing side of the oil supply passage. A fuel injection apparatus comprising: a spring that is configured to provide a relief mechanism at an initial portion of a piston stroke between the holder and the piston.   The fuel injection device according to claim 1, wherein the escape mechanism is formed by providing a stepped portion at an end of the piston. The fuel injection apparatus according to claim 1, wherein the escape mechanism is formed by providing an orifice in the holder.

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