JPS63117159A - Accumulator type fuel injector - Google Patents

Abstract

PURPOSE:To prevent occurrence of erroneous fuel injection quantity due to variation of operating speed entirely, by constructing an inlet valve with a spool valve. CONSTITUTION:The position of a spool 39 is determined by the balance between the inner pressure in a regulating accumulation chamber 5 and a hollow hole 41 and the inner pressure in a bias chamber 40. If the volume in the bias chamber 40 is set properly, an inlet valve 17 can be closed by moving the spool 39 to a top dead center when the inner pressure in a pump chamber 15 and the regulating accumulation chamber 5 is boosted to a predetermined level for closing a check valve. Here, the open valve timing of the inlet valve 17 is matched with that being achieved when the inner pressure of the pump chamber 15 reaches to the predetermined check valve closing pressure, and when a plunger 16 lowers furthermore, fuel is pressure fed from the pump chamber 15 to an accumulation type injection nozzle. When the spool 39 is positioned at a bottom dead center, the bias chamber 40 and the accumulation chamber 5 are communicated and the inner pressure of the bias chamber 40 is regulated to a normal referential level thus preventing erroneous control of injection quantity due to leakage of the inlet valve 17.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an accumulator fuel injection device used in diesel engines, etc., and in particular, to an accumulator fuel injection device that eliminates errors in injection amount control due to speed changes, and that The present invention relates to a pressure accumulation type fuel injection nozzle that eliminates errors in injection amount control due to errors in the inlet valve's bias voltage.

<Prior Art> In general, in a pressure accumulation type fuel injection device, after the pressure is regulated by a fuel supply device and the measured amount of fuel is pressurized into a fuel injection nozzle by a plunger pump, the pressure is regulated by a fuel supply device, and then the metered fuel is injected into a fuel injection nozzle by a check valve on the outlet side of the plunger pump. The pressure is reduced on the upstream side of the check valve, and the resulting internal pressure difference between the upstream side and the downstream side of the check valve opens the injection valve of the pressure accumulation type injection nozzle to inject fuel.

Since the amount of fuel metered in the fuel supply device is made to correspond to the engine load, the stroke of the plunger changes in response to the engine load.

When the stroke of the plunger changes in this manner, a gap is created between the plunger and the cam or rocker arm that drives it during a partial load, resulting in problems such as generation of noise such as impact sound.

Conventionally, in order to solve this problem, there is a system in which a spring is interposed in the drive system that drives the plunger so that the plunger and the cam or rocker arm are in constant contact with each other.

However, in this case, other problems arise, such as the stroke of the plunger being distorted due to vibrations of the spring and vibrations of the drive system such as the rocker arm.

Therefore, the inlet valve of the plunger pump is configured to open when the pressure is below a predetermined pressure, that is, the discharge pressure of the plunger, and close when the pressure is higher than that. A pressure accumulation type fuel injection device has been proposed in which an adjustment pressure accumulation chamber is connected and a check valve is provided further upstream of the pressure accumulation chamber.

That is, as shown in FIG. 10 (1) and FIG. 10 (2), a fuel supply device 1 that regulates the pressure of fuel and supplies it in a metered amount, a plunger pump 2, and a pressure accumulation type injection nozzle 3. An adjustment pressure accumulator 5 is branched and connected to a fuel supply path 4 that connects the fuel supply device 1 and the plunger pump 2.

The fuel supply device 1 includes a fuel tank 6 connected in series, a fuel pump 7 for pumping fuel from the fuel tank, a pressure regulator 8 for controlling the fuel supply pressure, and a fuel supply amount corresponding to the engine speed. Adjust! It has a governor 9 and a pressure pump 10 that pressure-adjusts the pressure and pumps the metered fuel. The press-in pump 10 includes a pump chamber 11, a plunger 12 that moves in and out of the pump chamber 11, and check valves 13 and 14 connected to the upstream and downstream sides of the pump chamber 11, respectively.

The plunger pump 2 also includes a pump chamber 15, a plunger 16 that enters and exits the pump chamber 11, an inlet valve 17 connected to the upstream side of the pump chamber 15, and a pump chamber 15.
A check valve 18 is provided, which is connected to the downstream side of the valve. This inlet valve 17 is connected to the bias spring 19 when the internal pressure of the pump chamber 15 is
Consists of a seat valve that closes when the urging force of
The check valve 18 is opened when the internal pressure of the pump chamber 15 exceeds a predetermined discharge pressure.

Further, the pressure accumulation type injection nozzle 3 includes an injection pressure accumulation chamber 20 and an injection valve 21 that opens and closes an outlet of the injection pressure accumulation chamber 20.

According to the conventional pressure accumulation type fuel injection device configured in this way, the injection pressure accumulation chamber 2 is transferred from the pump chamber 15 of the plunger pump.
In the process of retracting the plunger 16 from the bottom dead center to the top dead center after discharging fuel to zero, the internal pressure in the pump chamber 15 decreases and the difference in internal pressure between the upstream side and the downstream side of the check valve 18 increases. The injection valve 21 is opened above a predetermined injection valve opening pressure,
Fuel is injected. The position of the plunger 16 when the fuel injection ends is below the top dead center, and from this point on, the plunger 16 controls the fuel pressure injected into the pump chamber 15 from the adjustment pressure accumulation chamber 5 in order to compensate for the drop in the internal pressure of the pump chamber 15. It is completely returned to top dead center while being pressed by the cam or rocker arm. Thereafter, the measured amount of fuel is press-injected into the adjustment pressure storage chamber 5 from the upstream fuel supply device 1, and after this fuel supply is completed, the plunger 1G is lowered from the top dead center by a cam or a rocker arm. During this plunge 1
6, first, fuel flows back from the pump chamber 15 to the adjustment pressure accumulator chamber 5 at a pressure lower than the discharge pressure. The remaining amount of fuel in the pump chamber 15 goes to the adjustment pressure accumulation chamber 5 first! l1l
When the amount of fuel pressurized is equal to l, the pump chamber 1
5 reaches the discharge pressure, the inlet valve 17 is closed, and at the same time the check valve 18 is opened and discharge from the pump chamber 15 begins.

Therefore, according to this conventional pressure accumulation type fuel injection device, the plunger 16 is always returned to the top dead center and is always in contact with the driving cam or rocker arm, so that the impact noise caused by the plunger hitting the cam or rocker arm is noisy. will no longer occur, and noise will be reduced.

[Problem that the invention seeks to solve]

By the way, in this way, the inlet valve 17 of the plunger pump 2
In a conventional pressure accumulation type fuel injection device in which the inlet valve is configured with a seat valve, a pressure gradient is generated between the pump chamber 15 side and the upstream side of the inlet valve 17 when the inlet valve 17 is closed. The maximum lift amount of the inlet valve 17 must be set taking into account the lift amount due to, however,
The above pressure gradient increases as the engine speed increases, and the resulting lift amount also changes in response to the engine speed, so it is extremely difficult to appropriately set the maximum lift amount of the inlet valve 17. Therefore, there is a problem that an error occurs in the injection amount control due to the speed change. That is, in the high-speed operation region, the pressure gradient becomes large, and the pump chamber 15
Before the internal pressure of the pump chamber 15 reaches the regular discharge pressure, the inlet valve 17 closes and the fuel injection amount increases, and the pressure gradient becomes small in the low-speed operation region, and when the internal pressure of the pump chamber 15 reaches the regular discharge pressure. There is a problem that the closing of the inlet valve 17 is delayed, resulting in insufficient fuel injection amount.

Further, the bias means for setting the closing pressure and opening pressure of the inlet valve 17 is composed of a bias spring 19, and variations in the valve closing pressure may occur due to manufacturing errors in the bias spring 19, and vibrations of the bias spring 19 may cause variations in the closing pressure. There is also the problem that errors tend to occur in the fuel injection amount.

In order to solve this problem, the present inventor constructed the inlet valve with a spool valve, and used supplied fuel sealed at a predetermined reference pressure as bias means for setting the valve closing pressure and valve opening pressure. I came up with the idea of using .

In this case, as will be described later, by configuring the inlet valve with a spool valve, it is possible to eliminate errors in injection control due to pressure gradients that occur between the upstream and downstream sides of the inlet valve. By using the supplied fuel sealed in the inlet valve, errors in valve closing pressure and valve opening pressure due to manufacturing errors in the bias means are eliminated, and errors in injection amount control due to vibrations in the bias means are also eliminated. It has been discovered that there is a problem in that the fuel pressure (bias pressure) that controls the valve closing pressure of the engine fluctuates due to leakage between the spool and the spool chamber that houses it, which can cause errors in injection amount control. .

The present invention has been made in consideration of the above-mentioned circumstances, and it is possible to overcome the above conventional problems by configuring the inlet valve with a spool valve and using supplied fuel sealed at a predetermined pressure instead of a bias spring. It is an object of the present invention to provide a pressure accumulation type fuel injection device that solves the above problems and eliminates errors in injection amount control due to leakage of the inlet valve that may occur in this case.

Means for Solving Problem C] In order to achieve the above object, the pressure accumulation type fuel injection device according to the present invention includes a pressure accumulation type injection nozzle, a plunger pump for pressurizing fuel into the injection nozzle, and a plunger pump for pressurizing the fuel into the pressure accumulation type injection nozzle. The pressure is regulated and! The plunger pump includes a pump chamber, and a fuel supply device that supplies FJI fuel.
A plunger that is moved in and out of the pump, an inlet valve connected to the inlet side of the pump chamber, and a check valve connected to the outlet side of the pump chamber are provided, and the fuel pressure on the upstream side of the inlet valve is A pressure reducing device that reduces the pressure at a predetermined timing is connected to the inlet valve, and the inlet valve includes a spool and a spool chamber that slidably accommodates the spool, and the spool has a hollow hole extending from one end of the spool to the vicinity of the other end. , a main valve hole extending from one end side half of the hollow hole to the circumferential surface, a bias valve hole extending from the other end of the hollow hole to the circumferential surface, and an inlet hole extending from an intermediate portion of the hollow hole to the circumferential surface. An adjustment pressure accumulation chamber for adjusting the stroke of the plunger of the plunger pump to a full stroke is defined at one end of the spool chamber by the spool, and at the other end of the spool chamber, A bias chamber that urges the spool toward one end is defined, and a half of the circumferential surface of the spool chamber on the adjustment pressure accumulation chamber side is blocked from the main valve hole when the spool is located at the stroke end on the bias chamber side. When the spool is located closer to the adjustment pressure accumulation chamber, a main passage that communicates the pump chamber with the main valve hole is opened, and the inlet hole is connected to the middle part of the circumferential surface of the spool chamber. An inlet passage connected to a fuel supply device, a pressure reduction device, or a reference pressure setting device is opened, and a bias chamber side half of the circumferential surface of the spool chamber has an inlet passage connected to the fuel supply device, a pressure reduction device, or a reference pressure setting device. A bias pressure correction passage communicating the bias chamber and the bias valve hole is opened.

[Operation] In the above configuration, the fuel supply from the fuel supply device is located at the top dead center where the plunger leaves the pump chamber the most, and the spool is located at the stroke end on the adjustment pressure accumulation chamber side, that is, the bottom dead center. , and the internal pressures of the bias chamber, pump chamber, adjustment pressure accumulator chamber, and hollow hole are at a predetermined reference pressure. When fuel is supplied from the fuel supply device, the internal pressure in the pump chamber, adjustment pressure storage chamber, and hollow hole increases, and the spool rises from the bottom dead center to compress the fuel in the bias chamber, increasing the internal pressure in the bias chamber. The spool is moved to a position where the internal pressure of the adjustment pressure accumulator and the hollow hole is equal to the internal pressure of the bias chamber.

The position of the spool corresponds to the amount of fuel supplied; if the amount of fuel supplied is large, it will be close to top dead center, and if the amount of fuel supplied is small, it will be close to bottom dead center. After this, in the process of the plunger descending from top dead center by the cam and rocker arm, the internal pressure of the pump chamber, adjustment pressure storage chamber, and hollow hole increases, and this increase in internal pressure causes the spool to move toward the end of the stroke on the bias chamber side. (top dead center), and fuel flows back from the pump chamber to the adjustment pressure accumulation chamber via the inlet valve. Then, when the internal pressure of the pump chamber, adjustment pressure storage chamber, and hollow hole reaches the opening pressure of the check valve of the plunger pump (check valve opening pressure), the spool reaches top dead center, and the pump chamber and adjustment pressure The room is blocked off. The position of the above spool is determined by the balanced relationship between the internal pressure of the adjustment pressure storage chamber and the hollow hole communicating with the pump chamber and the internal pressure of the bias chamber, and the pressure generated between the upstream and downstream sides of the inlet valve during backflow. Determined independently of slope. Therefore, if the volume of the bias chamber is set appropriately, the spool can be moved to the top dead center and the inlet valve can be closed when the internal pressure of the pump chamber and adjustment pressure storage chamber rises to the predetermined check valve opening pressure. Can be done.

In this case, the closing timing of the inlet valve coincides with the time when the internal pressure in the pump chamber reaches the predetermined check valve opening pressure, regardless of the engine operating speed, and after this, the plunger further descends. Fuel is forced into the pressure accumulation type injection nozzle from the pump chamber.

Therefore, in this way, by accurately timing the closing of the inlet valve when the pump chamber reaches a predetermined internal pressure, errors in injection amount control due to engine speed can be eliminated.

After the inlet valve is closed, the plunger is further lowered to force fuel into the pressure accumulation type injection nozzle.

In order to inject fuel, after the injection of fuel is completed, the internal pressure in the pump chamber of the plunger pump is reduced, and the difference between the internal pressure in the injection pressure accumulation chamber of the pressure accumulation type injection nozzle and the internal pressure in the pump chamber is increased to a predetermined value or higher, and then the injection valve is opened. This is done by making a valve.

It is possible to reduce the pressure in the pump chamber by raising the plunger, but in order to increase the opening speed of the injection valve, it is possible to raise the spool by reducing the internal pressure in the adjustment pressure storage chamber and hollow hole of the inlet valve using a pressure reducing device. It is advantageous to open the inlet valve by lowering from the dead center and further reduce the internal pressure in the pump chamber, the regulating pressure accumulator and the hollow hole by means of a pressure reducing device. When reducing the internal pressure in the pump chamber with this pressure reducing device, stop the pressure reduction after the end of fuel injection, move the spool to the bottom dead center side using the internal pressure in the bias chamber, and pump the fuel in the adjustment pressure accumulation chamber. By press-fitting the plunger into the chamber, the plunger is returned to the top dead center while being pressed against the cam or rocker arm.

In this way, by returning the plunger to the top dead center while pressing it against the cam or rocker arm, a gap is prevented from forming between the plunger and the cam or rocker arm, and the cam or rocker arm hits the plunger. It is possible to prevent the occurrence of impact noise that would otherwise occur. In addition, when the internal pressure of the pump chamber is reduced due to the rise during plunging, the spool is lowered from the top dead center by reducing the internal pressure of the adjustment pressure accumulation chamber and the hollow hole with a pressure reducing device after the end of fuel injection. After opening the inlet valve, the pressure reduction is stopped, and the spool is moved to the bottom dead center side by the difference in internal pressure between the bias chamber and the adjustment pressure accumulation chamber, and the fuel in the adjustment pressure accumulation chamber is pressurized into the pump chamber. By returning to the top dead center while pressing the plunger against the cam or rocker arm, it is possible to prevent a gap from forming between the plunger and the cam or rocker arm, and prevent the cam or rocker arm from hitting the plunger. It is possible to prevent the occurrence of impact noise caused by

In addition, since the closing pressure and opening pressure of the inlet valve are set by the supplied fuel sealed at a predetermined pressure, errors in the closing pressure and opening pressure due to manufacturing errors are prevented, and vibrations of the biasing means are prevented. This eliminates errors in injection amount control and injection timing control.

Before the next fuel supply from the fuel supply device starts, the spool is returned to the bottom dead center.

Moreover, the internal pressures of the pump chamber, the adjustment pressure accumulator chamber, and the hollow hole are adjusted to the reference pressure before the spool returns to the bottom dead center.

If the pump chamber is to be depressurized by the rise during the plunge during fuel injection, by appropriately setting the depressurizing capacity of the pressure reducing device, when the spool returns to the bottom dead center, the pump chamber and the adjustment accumulator pressure can be reduced. The internal pressure of the chamber and hollow hole can be returned to the standard pressure, but when the pump chamber is depressurized by a pressure reducing device during fuel injection, it is necessary to set the pressure reducing capacity of the pressure reducing device in accordance with the maximum injection amount. Because there is
During normal operation, the internal pressures in the pump chamber, hollow hole, and adjustment accumulator chamber will fall below a predetermined reference pressure by the time the spool returns to the bottom dead center. As a result, the plunger cannot be pushed up to a predetermined top dead center, and a gap is created between the plunger and the cam or rocker arm that drives the plunger, resulting in a problem of impact noise. However, this problem can be solved by connecting a reference pressure setting device to the plunger pump to reduce the fuel pressure upstream of the cough inlet valve, and then at another time before the spool reaches the bottom dead center. This problem can be solved by restoring the fuel pressure to a predetermined reference pressure.

By the way, when the above-mentioned inlet valve is configured with a spool valve, for example, while the plunger is descending through its effective stroke, the valve is pressurized to a level higher than the check valve opening pressure through the fitting gap between the plunger and the plunge chamber. Fuel in the pump chamber may leak into the bias chamber. When such a leak occurs,
When the lowering of the spool is mechanically restricted to the regular bottom dead center, the internal pressures of the pump chamber, hollow hole, and adjustment pressure storage chamber are returned to the predetermined standard pressure, and the spool returns to the bottom dead center. Sometimes the internal pressure in the bias chamber becomes higher than the predetermined reference pressure, and if the spool can move below the normal bottom dead center, the internal pressure in the pump chamber, hollow hole, and adjustment pressure accumulator becomes higher than the predetermined standard pressure. When the pressure is returned to the standard pressure, there is a possibility that the spool will be positioned below the normal bottom dead center due to the opposing internal pressure in the bias chamber. In addition, fuel in the bias chamber leaks through the gap between the spool and the circumferential surface of the spool chamber into the hollow hole that is depressurized by the pressure reducing device, and when the internal pressure of the bias chamber reaches the standard pressure, the spool dies under normal conditions. It may be located closer to top dead center than the point.

If the internal pressure of the bias chamber changes due to leaks in this way, errors will occur in the spool position or the internal pressure of the bias chamber when the internal pressures of the pump chamber, adjustment pressure storage chamber, and hollow hole are restored to the standard pressure, resulting in injection Errors will occur in quantity control.

In other words, if the internal pressure in the bias chamber becomes high due to leakage, the spool valve will move further below the normal bottom dead center when the internal pressure in the pump chamber, adjustment pressure storage chamber, and hollow hole is adjusted to the standard pressure. or the internal pressure of the bias chamber becomes higher than the predetermined reference pressure, and the spool is located closer to bottom dead center than it should be when pressurizing the metered and pressure-regulated fuel. When the plunger is lowered, the inlet valve will not close unless the pressure becomes higher than the non-return closing valve pressure (and the fuel injection amount will decrease. Conversely, if the internal pressure of the bias chamber decreases due to leakage) If the pressure is low,
When the internal pressures of the pump chamber, adjustment pressure storage chamber, and hollow hole are adjusted to the standard pressure, the spool valve is positioned closer to the top dead center than the normal bottom dead center, and the fuel whose pressure has been regulated by 111 is pressurized. The spool is located closer to top dead center than it should be, and when the plunger is lowered, the inlet valve closes at a pressure lower than the check valve closing pressure, increasing the fuel injection amount. .

However, according to the present invention, when the spool is located at the bottom dead center, the bias chamber is communicated with the hollow hole through the bias pressure correction passage and the bias valve hole, so the internal pressure of the bias chamber is also maintained at the predetermined reference pressure. The adjustment is made so that the spool is accurately positioned at the regular bottom dead center before the next fuel supply starts from the fuel supply system, and there is no error in injection amount control due to an error in the spool position before the start of fuel supply due to inlet valve leakage. occurrence is prevented.

<Effects of the Invention> As described above, according to the present invention, by configuring the inlet valve with a spool valve, the plunger pump Since the valve is closed in accordance with the internal pressure of the pump chamber, it is possible to completely prevent errors in the fuel injection amount due to changes in operating speed.

In addition, since the pressure of the supplied fuel is used for the inlet valve's piascus, it is possible to prevent errors in valve closing pressure and valve opening pressure due to manufacturing errors or vibrations of the bias means. It is possible to prevent errors in control and injection timing control.

Furthermore, when the spool is at the bottom dead center, the bias chamber that applies a bias pressure to the spool of the inlet valve communicates with the adjustment pressure accumulation chamber, and the internal pressure of the bias chamber is adjusted to the regular reference pressure. The position of the spool before the start of supply is always at the regular bottom dead center, and it is possible to prevent errors in injection amount control due to leakage from the inlet valve.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is an equivalent circuit diagram of the pressure accumulation type fuel injection device according to the present invention, and FIGS. 2 to 8 are longitudinal cross-sectional views sequentially showing the operation of the unit injector. The state at the start of fuel supply is shown, and the third
The figure shows the state when the fuel supply ends, Fig. 4 shows the state when the internal pressure of the pump chamber etc. reaches the discharge pressure, Fig. 5 shows the state when the plunger pump is discharging, and Fig. 6 shows the state when the plunger pump is discharging. The state of the plunger pump at the end of discharge is shown, FIG. 7 shows the state from the start of injection until ignition, and FIG. 8 shows the state during fuel injection after ignition. Also, Figures 9 (1) to 9
Figure (6) is a time chart showing the operation of the unit injector, Figure 9 (1) shows changes in the internal pressure of the adjustment pressure accumulator, Figure 9 (2) shows changes in the position of the spool, Figure 9 (3) shows the change in the position of the plunger,
Figure 9 (4) shows the change in the internal pressure of the pump chamber;
5) shows the change in the opening degree of the injection valve, and FIG. 9 (6) shows the change in the internal pressure of the first pressure accumulating chamber, the change in the internal pressure of the second pressure accumulating chamber, and the change in the fuel injection rate.

This pressure accumulation type fuel injection device includes a fuel supply device 1 that regulates the pressure of fuel and supplies the measured amount, a plunger pump 2, and a pressure accumulation type injection nozzle 3. 3 is integrally assembled as a unit injector U.

The above fuel supply amount M, 1 is determined by the fuel tank 6 connected in series, the fuel pump 7 that pumps fuel from the fuel tank, the pressure regulator 8 that controls the fuel supply pressure, and the fuel supply that corresponds to the engine rotation speed. It has a meter (governor) 9 that adjusts the supply amount, and a pressure pump 10 that pressure-adjusts and pumps out #A amount of fuel. The press-in pump 10 is composed of a pump chamber 11, a plunger 12 that moves in and out of the pump chamber 11, and check valves 13 and 14 connected to the upstream and downstream sides of the pump chamber 11, respectively. .

The unit injector U has an injection pipe 22 and a main body 23, and has a vertical shaft (indicated as a horizontal axis in FIGS. 2 and 4) that is open to the top surface of the main body 23 at one side of the main body 23. )
A plunger chamber 24 is formed, and this plunger chamber 24
A plunger member 16 is inserted into the plunger 16 in the form of an oil chamber so as to be able to move forward and backward. Further, a pump chamber 15 is defined in the lower part of the plunger chamber 24 by the plunger 16 .

The injection pipe 22 is divided into an upper part 22a and a lower part 22b. A downwardly facing receiving surface 25 is formed in the middle part of the upper part 22a of the injection pipe 22, and a lower half part of the upper part 22a than the receiving surface 25 penetrates into the main body 23 in the form of an oil chamber. The lower part 22b of the injection pipe 22 is screwed onto the lower end of the upper part 22a.
The main body 23 is held between the upper end surface of b and the receiving surface 25.

A check valve chamber 26 for housing the check valve 18 of the plunger pump 2 is formed in the lower half of the upper part 22a of the injection pipe 22.
A pressure accumulation passage 27 communicating with the check valve chamber 26 is formed in the lower part. This pressure accumulation passage 27 has a nozzle hole 28 at its tip, and is opened and closed near the nozzle hole 28 by the injection valve 21. This injection valve 21 is composed of a needle valve, and its valve shaft 29 passes through a pressure accumulation passage 27 and a check valve chamber 26.
Further, it penetrates the upper end wall 30 of the reversing valve chamber 26 in the form of an oil chamber and is movable forward and backward, and enters into a valve-closing spring chamber 31 formed in the upper half of the upper portion 22a. This valve shaft 29 is connected to the check valve chamber 26.
The valve seat 32 of the check valve 18 is expanded in the radial direction near the upper end of the check valve 18 . This valve seat 3
2 and the check valve 18 on the upper end side of the check valve chamber 26 is connected to the pump chamber 1 through a communication passage 34.
5. Then, this valve seat 32 and the check valve 18
The first injection pressure accumulation chamber 35 is constituted by the lower end portion of the check valve chamber 26 defined by the pressure accumulation passage 27 . The injection pressure accumulation chamber 20 of this pressure accumulation type injection nozzle 3 is composed of this first injection pressure accumulation chamber 35 and a second injection pressure accumulation chamber 38 connected to this through a check valve 36 and a pressure setting valve 37. The internal pressure of the two-injection pressure accumulation chamber 38 is maintained at a predetermined high pressure or higher. This second injection storage room 38 is formed in an annular space formed between the main body 23 and the injection pipe 22 by reducing the middle part of the lower half of the upper part 22a of the injection pipe 22 in the radial direction,
The check valve 36 and the pressure setting valve 37 are arranged on the other side of the main body 23.

The inlet valve 17 of the plunger pump 2 is connected to the plunger 1
Although it is possible to provide the unit injector U separately from the unit injector 6, here it is incorporated into the plunger 16 in order to make the unit injector U small and compact. That is, the inlet valve 17 has a spool valve consisting of a spool chamber 38 formed coaxially within the plunger 16 and a spool 39 slidably housed in the spool chamber 38.

The spool 39 is located at one end of the spool chamber 38.
An adjustment pressure accumulation chamber 5 for adjusting the stroke of the plunger 16 to a full stroke is defined by the spool chamber 38, and the spool 39 is placed at one end of the spool chamber 38.
That is, a bias chamber 40 biased toward the adjustment pressure accumulation chamber 5 is defined.

The spool 39 has a hollow hole 4 extending from its end face on the adjustment pressure accumulation chamber 5 side to near the end face of the bias chamber 40.
1, a main valve hole 42 extending from the adjustment pressure accumulator 5 side half of the hollow hole 41 to the circumferential surface, a bias valve hole 43 extending from the other end of the hollow hole 41 to the circumferential surface, and the hollow hole 24. An inlet hole 44 is formed extending from the intermediate portion to the circumferential surface.

On the other hand, when the spool 18 is located at the stroke end on the bias chamber 40 side, that is, at the top dead center, the half of the peripheral wall of the plunger 9 on the adjustment pressure storage chamber 5 side is blocked from the main valve hole 42, and the spool 18 A main passage 45,46 is provided which communicates with the main valve hole 42 when the valve is lowered below the top dead center. The main passages 45 and 46 may be formed of a single circular hole, but here, in order to limit the amount of fuel injected before ignition to a small value, the main valve hole 45 and 46 are connected as soon as the spool 39 descends from the top dead center. A micro passage 45 communicating with the spool 3
9 is divided into a large diameter passage 46 which communicates with the main valve hole 42 when the valve 9 is lowered to a predetermined position on the bottom dead center side. In addition, this main passage 45, 46 is always connected to the pump chamber 15.
will be communicated to.

Further, the inlet hole 44 is provided in the middle part of the peripheral wall of the plunger 9.
An inlet passage 47 is formed to communicate the spool 39 with the fuel supply device 1, and the spool 39 is located in the bias chamber 40 side half of the circumferential wall of the plunger 9 at the stroke end on the adjustment pressure accumulation chamber 5 side, that is, at the bottom dead center. A bias pressure correction passage 48 is formed which communicates the bias valve port 43 with the bias chamber 40 when the bias valve port 43 is positioned.

The inlet passage 47 is connected to the fuel supply passage 4 connecting the plunger pump 2 and the fuel supply device l through a passage 49 formed in the main body 23, and the bias chamber 40 is connected to the fuel supply passage 4 through a bias passage 50. It is communicated with the pressure accumulation chamber 51. This bias pressure accumulation chamber 51 is composed of a space 52 formed in the upper end of the injection pipe 22 and the valve-closing spring chamber 31, and when the spool 39 is located at the top dead center, a bias pressure is applied via the bias chamber 40. It communicates with the valve hole 43.

A switching valve 53 is interposed in the fuel supply path 4, and by switching the switching valve 53 at a predetermined timing, the hollow hole 41 and the adjustment pressure accumulation chamber 5 are connected to the passage 49, the inlet passage 47, and the inlet hole 44. a fuel supply device 1 via;
The pressure reducing device 54 and the reference pressure setting device 55 are switched and connected.

The pressure reducing device 54 is composed of a drain passage 56 that connects the switching valve 53 to the fuel tank 6, and a suction pump 56 and a check valve 57 that are interposed in series with the drain passage 56.
The reference pressure setting device 55 includes a pressure regulator 8 that also serves as the pressure regulator 8 of the fuel supply device 1, and an outlet of the pressure regulator 8 connected to the switching valve 5.
3, and a check valve 60 interposed therebetween.

A valve-closing spring 61 is inserted into the valve-closing spring chamber 31 to bias the injection valve 21 to close.

Next, the operation of this pressure accumulation type fuel injection device will be explained in the fuel supply device 1.
A step-by-step explanation will be given starting from the point in time when fuel supply starts.

At time a in FIG. 9 (hereinafter simply referred to as time a, and the same applies to each time point after time 5 in FIG. 9) when fuel supply from the fuel supply device 1 starts, as will be described later,
The plunger 16 is located at the top dead center as shown in FIGS. 4 and 9 (3), and the spool 39 is located at the top dead center as shown in FIGS. 4 and 9 (2).
) is located at the bottom dead center as shown. In addition, the pump chamber 15
, the internal pressures of the adjustment pressure accumulation chamber 5, the hollow hole 41, the bias chamber 40 and the bias pressure accumulation chamber 51 become the reference pressure P0 set by the reference pressure setting device 55, as shown in FIGS. 9(1) and (4). ing.

When the fuel supply device 1 supplies fuel to the unit injector U from this point a, the internal pressures of the pump chamber 15, the adjustment pressure storage chamber 5, and the hollow hole 41 rise, and the spool 39 is raised from the bottom dead center.

As a result, the internal pressure of the bias chamber 40 and the bias pressure accumulator chamber 51 changes before the bias chamber 40 and the bias valve hole 43
bias chamber 40 and bias pressure accumulation chamber 51
A certain amount of fuel at a reference pressure Pa is sealed in the tank. Spool 3
9 rises, the fuel sealed in the bias chamber 40 and the bias pressure accumulation chamber 51 is compressed, and the bias chamber 40
And the internal pressure of the bias pressure accumulation chamber 51 increases. The spool 39 is connected to the internal pressure of the pump chamber 15, the adjustment pressure accumulation chamber 5, and the hollow hole 41, and the bias chamber 40 and the bias pressure accumulation chamber 51.
At time b, when the internal pressure of the cylinder is moved to a balanced position and the fuel supply ends, as shown in FIG. 3, the cylinder stops at a height corresponding to the supplied fuel amount, that is, the injection amount. In other words, when the injection amount is large, the internal pressure of the pump chamber 15, the adjustment pressure storage chamber 5, and the hollow hole 41 increases, so the bias chamber 40
When the fuel in the bias pressure accumulator 51 is greatly compressed and the position of the spool 39 becomes high, and the injection amount is small,
Since the increase in internal pressure in the pump chamber 15, adjustment pressure storage chamber 5, and hollow hole 41 becomes smaller, the compression of the fuel in the bias chamber 40 and bias pressure storage chamber 51 becomes smaller, and the position of the spool 39 becomes lower.

Next, in the process from time C to time R when the cam or rocker arm (not shown) pushes down the plunger 16 from the top dead center toward the bottom dead center, the volume of the pump chamber 15 first decreases to compensate for this decrease. amount of fuel is in the main passage 45
．． 46 and the main valve hole 42 into the adjustment pressure storage chamber 5, and as shown in FIG. 4, the spool 39 is raised to the top dead center before the plunger 16 reaches the bottom dead center. While the spool 39 is rising, the internal pressure increase in the pump chamber 15 is slowly suppressed by the backflow of fuel into the adjustment pressure storage chamber 5.
Moreover, the internal pressure of the pump chamber 15 is suppressed to a lower pressure than the valve opening pressure (check valve opening pressure) P4 of the check valve 18. Spool 39
When reaches the top dead center, the pump chamber 15 is cut off from the adjustment pressure storage chamber 5, and as the plunger 16 further descends, the internal pressure of the pump chamber 15 becomes higher than the check valve opening pressure of the check valve 18. As shown in FIG. 5, the check valve 18 is opened and fuel is discharged to the pressure accumulation type injection nozzle 3.

The internal pressure of the pump chamber 15, the adjustment pressure accumulation chamber 5, and the hollow hole 41 when the spool 39 reaches the top dead center can be adjusted to the check valve opening pressure by appropriately setting the volumes of the bias chamber 40 and the bias pressure accumulation chamber 51. It can be matched with P. In this way, when the spool 39 reaches the top dead center and the inlet of the pump chamber 15 is shut off when the internal pressure of the pump chamber 15 reaches the check valve opening pressure P, the inlet is shut off. The downward stroke of the plunger 16 up to this point becomes an invalid stroke in which the plunger pump 2 does not discharge, and the downward stroke of the plunger 16 after this point becomes an effective stroke. In this case, the position of the spool 39 is
Regardless of the pressure gradient that occurs between the pump chamber 15 side and the adjustment pressure storage chamber 5 side of No. 2, it is determined by the balance relationship between the internal pressure of the adjustment pressure storage chamber 5 and the internal pressure of the bias chamber. Therefore, the fuel pressure in the pump chamber 15 when the pump chamber 15 is cut off from the adjustment pressure storage chamber 5 and the spool 3 are not affected by the pressure gradient that changes depending on the engine speed.
9, that is, the volume of fuel sealed between the inlet valve 17 and the check valve 18, can be accurately controlled in accordance with the amount of fuel supplied, without causing errors due to changes in engine speed. This allows for more accurate injection amount control.

From time d when the plunger pump 2 starts discharging until the plunger 16 reaches the bottom dead center, the fuel discharged from the plunger pump 2 is first pressurized into the first injection pressure accumulation chamber 35, and suddenly the first injection pressure accumulation The internal pressure of the chamber 35 is increased. After time 0, when this internal pressure exceeds the set pressure of the pressure setting valve 37, the check valve 36 is opened and the internal pressure of the second injection pressure accumulation chamber 38 rises above the set pressure. is opened, and the internal pressures of the first injection pressure accumulation chamber 35 and the second injection pressure accumulation chamber 38 are equally increased. The check valve 36 is closed when the pressure setting valve 37 is opened and the internal pressures of the first injection pressure accumulation chamber 35 and the second injection pressure accumulation chamber 38 become equal, and after the first point in time when the plunger 16 reaches the bottom dead center, the check valve 36 is closed. As shown in the figure, check valve 18 is closed.

In addition, in FIG. 9 (4), the change in the internal pressure of the pump chamber 15 in this embodiment is shown by a solid line, and the change in the internal pressure of the pump chamber 15 when the injection pressure accumulation chamber 20 is composed of a single chamber is shown by a broken line. It is shown in Further, in FIG. 9(6), changes in the internal pressure of the first injection pressure accumulation chamber 35 and the second injection pressure accumulation chamber 38 of this embodiment are shown by solid lines, and the injection pressure accumulation chamber 20 is composed of a single chamber. The change in the internal pressure of the injection pressure accumulation chamber 20 in this case is shown by a broken line.

Next, by reducing the internal pressure of the pump chamber 15, the differential pressure between the internal pressure of the valve-opening pressure reducing chamber 33 and the internal pressure of the first injection pressure accumulating chamber 35 is made equal to or higher than a certain level, and the injection valve 21 is opened to inject the fuel. The liquid is injected from the nozzle hole 28.

As a method of reducing the internal pressure of the pump chamber 15, there is also a method of raising the plunger 16 from the bottom dead center, but in this case, the rising speed of the plunger 16 is limited by the profile of the cam that drives the plunger 16, and the pump Room 15
There is a problem in that the rate of reduction of the internal pressure cannot be increased beyond a certain level.

In this pressure accumulation type fuel injection device, the switching valve 53 is switched at a predetermined point g while the plunger 16 is kept at the bottom dead center, and the pressure reducing device 54 is connected to the inlet valve 17. By reducing the internal pressure of 5 and lowering the spool 39 from the top dead center, the main valve hole 42 is connected to the main passage 45.
．． The internal pressure of the pump chamber 15 is reduced by communicating with the pump chamber 15 via the pump 46 so as to be switched on and off.

In this way, in this pressure accumulation type fuel injection device, the pressure reducing device 5
3, the internal pressure of the pump chamber 15 is reduced by opening and closing the inlet valve 17, so the rate of reduction of the internal pressure of the pump chamber 15 can be increased and the opening speed of the injection valve 21 can be increased.

By the way, while the plunger 16 is descending from time d to time f, a leak occurs from the pump chamber 15 to the adjustment pressure storage chamber 5, which becomes higher than the check valve opening pressure P, and this leak causes the spool 39 to In the case of this embodiment in which the human loaf is mechanically restricted at the regular top dead center, when the plunger reaches the bottom dead center, the hollow hole 41 and the adjustment pressure accumulation chamber 5 are closed.
There is a possibility that the internal pressure of the check valve may rise to a higher pressure than the check valve closing pressure P4. If such a situation occurs, the communication between the main valve hole 42 and the main passages 45 and 46 will be interrupted after the plunger 16 reaches the bottom dead center and after the pressure reduction on the upstream side of the inlet valve 17, which will be described later, starts. The start timing may be delayed, the injection start timing may be delayed, or the main valve hole 42 and main passage 4 may
Communication with 5.46 becomes impossible and injection becomes impossible.

However, in this pressure accumulation type fuel injection device, between the time point d when the spool 39 is located at the top dead center and the time point g, the hollow hole 41 and the adjustment pressure accumulation chamber 5 are connected to the bias chamber 40 and the bias pressure accumulation chamber 5 through the bias valve hole 43. Since the internal pressure of the hollow hole 41 and the adjustment pressure accumulation chamber 5 is communicated with the bias chamber 4
0 and the same pressure as the internal pressure of the bias pressure accumulation chamber 51, the check valve opening pressure P
4, the balance between these internal pressures is restored, and the delay in injection timing and inability to inject due to the leakage from the pump chamber 15 to the adjustment pressure storage chamber 5 is prevented.

The change in the opening rate of the injection valve 21 is such that when the main passage is composed of a single circular hole, it becomes fully open almost at the same time as the valve opens, as shown by the broken line in Fig. 9 (5); When the passage is composed of a single circular hole and the injection pressure accumulation chamber 20 is composed of a single chamber, the fuel injection rate changes as shown by the broken line in Fig. 9 (6). Immediately after the start, the injection rate increases rapidly, and then gradually decreases.

In this embodiment, the minute passage 45 is communicated with the main valve hole 42 as shown in FIG. 7 at time h, which is shortly after the spool 39 begins to descend from the bottom dead center, and the internal pressure of the adjustment pressure accumulator 5 is adjusted by a minute amount. At the same time as increasing the pressure, the pressure reduction rate of the internal pressure of the pump chamber 15 is kept small, so that the opening amount of the injection valve 21, the fuel injection rate, and the internal pressure drop of the injection pressure accumulation chamber 20 are limited to a small value, and at time i of ignition after the start of injection, as shown in FIG. As shown in FIG.
The internal pressure is reduced, and by suddenly opening the injection valve 21 fully, a large amount of fuel is injected at once at high pressure. When the internal pressure of the injection pressure accumulation chamber 20 drops to the set pressure of the pressure setting valve 37 due to fuel injection, the pressure setting valve 37 is closed, and thereafter the internal pressure of the first injection pressure accumulation chamber 35 decreases rapidly. and,
As soon as the internal pressure of the first injection pressure accumulation chamber 35 falls to a predetermined valve closing pressure, the injection valve 21 is closed and injection is terminated.

In this way, by limiting the fuel injection rate during the period from the start of injection to ignition to a small value, it is possible to reduce the explosion noise at the time of ignition and reduce the operating noise. Furthermore, the internal pressure drop in the injection pressure accumulation chamber 20 during the period from the start of injection to ignition is limited to a small value, and at the time of ignition, the injection valve is suddenly opened to inject fuel at high pressure, and the internal pressure of the injection pressure accumulation chamber 20 is kept at a predetermined set pressure. By closing the second injection storage chamber 38 and switching the volume of the injection pressure storage chamber 20 to a small volume when the engine descends, the injection time can be shortened, which is advantageous in increasing the speed of the engine. .

After the fuel injection is completed, the internal pressures of the pump chamber 15, the hollow hole 41, and the adjustment pressure storage chamber 5 are stabilized at a predetermined pressure between the check valve closing pressure P4 and the reference pressure P0, and then at a predetermined point in time. The plunger 16 is then raised. In the process of raising the plunger 16, the internal pressures of the pump chamber 15, hollow hole 41, and adjustment pressure storage chamber 5 are slowly reduced to a predetermined reference pressure P0, and the spool 39 is lowered to the bottom dead center by the internal pressure of the bias chamber 40. be done. In addition, the internal pressure of the bias chamber 40 is reduced as the spool 39 descends from the top dead center to the bottom dead center.
The pressure is lowered from the check closing valve pressure P4 to the reference pressure P0.

By the way, when the pump chamber 15, the hollow hole 41, and the adjustment pressure storage chamber 5 are depressurized to open the injection valve 21 as described above, the magnitude and duration of the depressurization are adjusted to correspond to the maximum injection amount. Normally, when the spool 39 that lowers the plunger 16 descends to the bottom dead center, the internal pressures of the pump chamber 15, hollow hole 41, and adjustment pressure storage chamber 5 reach a predetermined reference pressure P0. The pressure is often lower than that of the When the internal pressure of the hollow hole 41 and the adjustment pressure storage chamber 5 becomes lower than the predetermined reference pressure P0, the spool 39 will be located closer to the bottom dead center than the original position when the next fuel supply is finished, The closing timing of the inlet valve 17 during the descent of the plunger 16 may be delayed, resulting in a decrease in the injection amount, or the inlet valve 17 may become unable to close, making injection impossible.

In this pressure accumulation type fuel injection device, in order to solve such a problem, the reference pressure setting device is set for an appropriate period from time 1 when the plunger 16 starts rising to time m when the spool 39 reaches the bottom dead center. 55 is connected to the inlet valve 17, and the internal pressures of the pump chamber 15, hollow hole 41, and adjustment pressure storage chamber 5 are adjusted to a predetermined reference pressure P0 at time m.

Further, the internal pressure of the bias chamber 40 is determined by the hollow hole 4 of the spool 39
The pressure may be reduced due to a leak when the plunger 16 is being depressurized, or the pressure may be increased due to a leak while the plunger 16 is descending through its stroke, and changes in the internal pressure of the bias chamber 40 due to this leak may be the cause. This may cause an error in injection amount control.

That is, when the internal pressure of the bias chamber 40 is reduced due to leakage, the spool 39 is placed above the bottom dead center when the internal pressure of the hollow hole 41 and the adjustment pressure storage chamber 5 is reduced to the predetermined reference pressure P0. Then, when the pressure is regulated and the metered amount of fuel is supplied, the spool 39 stops at the top dead center side of the original position, and after this, the plunger 16
When the internal pressure of the pump chamber 15, the hollow hole 41, and the adjustment pressure storage chamber 5 reaches the non-return valve closing pressure P4 when the inlet valve 17 is lowered, the inlet valve 17 is shut off with a delay, and the fuel injection amount is reduced. . Conversely, if the internal pressure of the bias chamber 40 is increased due to leakage, the spool 39 will be at the bottom dead center when the internal pressure of the hollow hole 41 and the adjustment pressure storage chamber 5 is reduced to the predetermined reference pressure P0. It is stopped mechanically, and the internal pressure of the bias chamber 40 becomes higher than the predetermined reference pressure P0, and then the pressure is regulated, and li! When the fuel is supplied, the spool 39
stops closer to the bottom dead center than its original position, and then when the plunger 16 is lowered, the internal pressures of the pump chamber 15, hollow hole 41, and adjustment accumulator chamber 5 reach the check valve closing pressure P4. Before this point is reached, the inlet valve 17 is shut off and the fuel injection amount increases.

However, in this pressure accumulation type fuel injection device, while the spool 39 is located at the bottom dead center, that is, between time point m and time point a of the next fuel supply start, the bias chamber 40 and the bias pressure accumulation chamber 51 are connected to the bias passage 48. and bias valve hole 43
The pump chamber 15, the hollow hole 41, and the adjustment pressure accumulation chamber 5 are connected via the
During this period, the internal pressures of the bias chamber 40 and the bias pressure accumulation chamber 51 are adjusted to the same predetermined reference pressure Pa as the internal pressures of the hollow hole 41 and the adjustment pressure accumulation chamber 5. As a result, errors in injection amount control occur due to leakage of the inlet valve 17 (variation in the spool position before the start of fuel supply or imbalance between the internal pressure of the bias chamber 40 and the internal pressure of the hollow hole 41 and the adjustment pressure accumulation chamber 5). is prevented.

[Brief explanation of the drawing]

FIG. 1 is an equivalent circuit diagram of a pressure accumulator fuel injection device according to an embodiment of the present invention, and FIGS. 2 to 8 are longitudinal cross-sectional views sequentially showing the operation of the unit injector. The state at the start of fuel supply to the third
The figure shows the state when the fuel supply ends, Fig. 4 shows the state when the internal pressure of the pump chamber etc. reaches the discharge pressure, Fig. 5 shows the state when the plunger pump is discharging, and Fig. 6 shows the state when the plunger pump is discharging. Figure 7 shows the state at the end of discharge of the plunger pump, Figure 7 shows the state after the start of injection until ignition, Figure 8 shows the state during fuel injection after ignition, Figures 9 (1) to 9. (6) is a time chart showing the operation of the unit injector, FIG. 9 (1) shows changes in the internal pressure of the adjustment pressure accumulator, FIG. 9 (2) shows changes in the position of the spool, and FIG. Figure 9 (3) shows the change in the position of the plunger, and Figure 9 (4)
shows the change in the internal pressure of the pump chamber, Fig. 9 (5) shows the change in the degree of opening of the injection valve, and Fig. 9 (6) shows the change in the internal pressure of the first pressure accumulator chamber and the internal pressure of the second pressure accumulator chamber. FIG. 10 (1) is an equivalent circuit diagram of a conventional pressure accumulation type fuel injection device, and FIG. 10 (2) is a longitudinal cross-sectional view of the unit injector, showing changes in fuel injection rate and fuel injection rate. 1...Fuel supply device, 2...Plunger pump, 3
...Pressure accumulation type injection nozzle, 5...Adjustment pressure accumulation chamber, 15
... Pump chamber, 16... Plunger, 17... Inlet valve, 18... Check valve, 38... Spool chamber, 39
... Spool, 40 ... Bias chamber, 41 ... Hollow hole, 42 ... Main valve hole, 43 ... Bias valve hole, 4
4... Entrance hole, 45.46... Main passage, 47...
Inlet passage, 48... Bias pressure correction passage, 54...
- Pressure reducing device, 55...Reference pressure setting device. Appetizer 3 3. Person making the amendment Name of the patent applicant related to the case Name Hitoyasuda Iron Works Co., Ltd. 4 Agent 5 Date of amendment order Sent on January 27, 1988 (
1) to Figure 9 (6) --- Shows changes. '' is corrected to ``Figure 9 is a time chart F showing the operation of the unit injector.'' (2) Correct Figure 9 as shown in the attached sheet.

Claims (1)

[Claims] 1. A pressure accumulation type injection nozzle 3, a plunger pump 2 that presses fuel into it, and a pressure regulated by the plunger pump,
The plunger pump 2 includes a pump chamber 15, a plunger 16 that is moved in and out of the pump chamber 15, and a plunger 16 that is connected to the inlet side of the pump chamber 15. the inlet valve 17 and the pump chamber 1
A check valve 18 connected to the outlet side of 5 is provided,
A pressure reducing device 54 is connected to reduce the fuel pressure upstream of the inlet valve 17 at a predetermined timing, and the inlet valve 17 includes a spool 39 and a spool chamber 38 that slidably accommodates the spool 39. 39 includes a hollow hole 41 extending from one end to the vicinity of the other end, a main valve hole 42 extending from the other end of the hollow hole 41 to the circumferential surface, and a main valve hole 42 extending from the other end of the hollow hole 41 to the circumferential surface. A bias valve hole 43 extending to the hollow hole 41 and an inlet hole 44 extending from the intermediate portion to the circumferential surface are formed. An adjustment pressure accumulation chamber 5 for adjusting the stroke is divided, and the spool 3 is located at the other end of the spool chamber 38.
A bias chamber 40 that biases the spool 39 toward one end side is partitioned, and a half portion of the circumferential surface of the spool chamber 38 on the adjustment pressure storage chamber 5 side has a bias chamber 40 that biases the spool 39 toward one end. main passages 45 and 46 that are shut off from the main valve port 42 and communicate the pump chamber 15 with the main valve hole 42 when the spool 39 is located closer to the adjustment pressure accumulation chamber 5 are opened; An inlet passage 47 that connects the inlet hole 44 to the fuel supply device 1, the pressure reducing device 54, or the reference pressure setting device 55 is opened in the middle of the circumferential surface of the chamber 38, and a bias on the circumferential surface of the spool chamber 38 is provided. A bias pressure correction passage 48 is opened in the 0-side half of the chamber 4 to communicate the bias chamber 40 and the bias valve hole 43 when the spool 39 is located at the stroke end on the adjustment pressure storage chamber 5 side. Features of pressure accumulation type fuel injection device