JPH071029B2 - Accumulation type fuel injection device - Google Patents

Description

Description: [Industrial field of application] The present invention relates to a pressure accumulation type fuel injection device used in a diesel engine.

[Conventional technology]

Conventionally, as a pressure-accumulation fuel injection device for a diesel engine, a device as shown in FIG. 6 has been disclosed.

The pressure-accumulation fuel injection device 50 is a fuel injection nozzle for supplying injection fuel to the pressure accumulation chamber 5 in order to spray or inject the fuel from the injection port 11 into the combustion chamber of the engine.
A needle valve 3 for opening and closing the injection port 11 is provided in a pressure accumulating chamber 5 of a main body 15 having 11 and a check valve 2 is slidably provided on the needle valve 3. That is, the check valve 2 is configured to be vertically slidable around the outer circumference of the needle valve 3. Further, the check valve 2 is urged by the spring force of the spring 4 so as to be pressed against the check valve seat 6 arranged on the upper surface side of the pressure accumulating chamber 5, and the check valve 2 shuts off the communication between the passage 13 and the pressure accumulating chamber 5. Moreover, a check valve outer peripheral gap 7 is formed between the peripheral surface of the check valve 2 and the peripheral surface of the pressure accumulating chamber 5.

In such a fuel injection device 50, the fuel pumped by the general fuel injection pump 8 driven by the engine overcomes the spring 4 due to the supply pressure of the fuel, and the check valve 2, the injection pipe 9, the passage 13, It enters the pressure accumulating chamber 5 through the through hole 14 of the check valve seat 6 and the check valve outer peripheral gap 7. Next, when the fuel pumping period by the fuel injection pump 8 ends, the injection pipe 9,
The internal pressure in the passage 13 and the through hole 14 of the check valve seat 6 rapidly decreases. Therefore, the force acting on the upper surfaces of the needle valve 3 and the check valve 2, that is, the portion indicated by the symbol A is released.

Therefore, the fuel pressure trapped in the pressure accumulating chamber 5 overcomes the spring force of the spring 4 to slide the check valve 2 and the needle valve 3 upward. Therefore, the injection port 11 is opened and fuel injection is started. When the fuel injection starts, the internal pressure of the pressure accumulating chamber 5 rapidly decreases, and the fuel is injected into the combustion chamber until the spring force of the spring 4 overcomes the fuel pressure in the pressure accumulating chamber 5. In the figure, reference numeral 12 indicates a slide portion of the needle valve 3.

Regarding the pressure-accumulation fuel injection device 50, the crank angle θ, the injection rate R, and the pressure P in the pressure accumulator chamber 5 have a graph relationship as shown in FIG. 7. The abscissa plots the crank angle of the engine, that is, the crank angle θ, and the ordinate plots the injection rate R and the pressure P in the pressure accumulating chamber 5. In this case, the injection amount Q is expressed by the following equation. That is, Q = V / K · (P _i −P _s ), where V is the volume of the accumulator, K is the elastic modulus of the fuel, P _i is the pressure of the accumulator, and P _s is the pressure of the needle valve 3 determined by the spring 4. Indicates valve closing pressure. In addition, the curve L shows a low load,
A curve H shows a high load. Further, a point B indicates a pumping start point of the fuel injection pump 8, and a point E indicates an end point of the pumping period of the fuel injection pump 8. Further, point D shows the injection start point of the injection port 11 of the fuel injection nozzle at low load, point C or E shows the injection start point of the injection port 11 at high load, and low load from point D to point θ _4. The fuel injection period at high load is shown from point C to point θ ₅ . Therefore, regarding the fuel injection amount Q, the curve 1 is under low load and the curve m is under high load.
Indicated by.

Further, as a conventional fuel injection device used for a diesel engine, there is one disclosed in Japanese Utility Model Laid-Open No. 58-66164. In this fuel injection device, a shaft rod having a needle valve for opening and closing the injection hole is provided in a pressure accumulation chamber of a main body having an injection hole, a check valve is slidably provided on the shaft rod, and the check valve is spring-loaded. Is urged toward the upper surface side of the valve to cut off the communication between the passage and the pressure accumulating chamber by the check valve, and a gap is provided between the peripheral surface of the check valve and the peripheral surface of the pressure accumulating chamber.

Further, in the fuel injection device, the main body is opposed to the upper end surface of the shaft rod, and the push rod is urged toward the shaft rod side by a spring to form a gap between the push rod and the shaft rod. It is held and the passage is opened to the upper surface of the pressure accumulating chamber at a position deviated from the upper end surface of the shaft rod.

Further, as a fuel injection nozzle, there is one disclosed in Japanese Utility Model Laid-Open No. 60-133172. The fuel injection nozzle supplies the fuel supplied from the pump through the check valve from the fuel supply passage to the high pressure chamber and from the high pressure chamber to the accumulator chamber accommodating the needle valve, and the fuel supplied to the high pressure chamber is increased. Needle valve that closes the injection hole at the tip of the nozzle by applying pressure to a low-pressure piston with a small diameter, pressurizing it with a small-diameter high-pressure plunger that is integral with the low-pressure piston, and accumulating in a pressure accumulating chamber, and then reducing the pressure applied to the low-pressure piston. To inject fuel from the injection hole, and is provided with pressure adjusting means for stepwise raising the needle valve when injecting fuel.

[Problems to be Solved by the Invention]

By the way, an adiabatic engine in which a cylinder head, a cylinder liner, a piston head, a valve, etc. are made of a ceramic material has already been disclosed. However, in the adiabatic engine, the temperature at the compression stroke end of the engine is higher than that of a general engine. Is extremely high, the time from the injection of fuel to the ignition, that is, the ignition delay is greatly shortened.

This means that the amount of fuel injected into the combustion chamber decreases by the engine ignition timing, premixed combustion immediately after engine ignition decreases, and there is a problem that the engine performance is adversely affected. ing. Therefore, in the adiabatic engine, it is effective to use a unit injector capable of high-pressure injection in order to shorten the fuel injection period as much as possible.

In particular, for adiabatic engines, a pressure-accumulation fuel injection device having a high initial injection rate at the start of injection is most suitable. Therefore, if the above pressure accumulation type fuel injection device is applied, the injection amount Q
For, since it is _{Q = V / K · (P} i -P s), in order to increase the injection rate R is able to raise the _{P i} is one way, the higher the _{P i,} the From the equation, when P _s is constant, the maximum injection amount increases. In order to prevent this, it is necessary to reduce the volume V of the pressure accumulating chamber 5. Such a pressure chamber 5
To reduce the volume V of is due to the structure of the fuel injection nozzle,
It's very difficult.

Further, in the fuel injection nozzle disclosed in Japanese Utility Model Laid-Open No. 60-133172, the fuel pressure is increased by providing pressure adjusting means for gradually raising the needle valve to atomize the fuel, The purpose is to increase the scattering distance and shorten the injection time, but high pressure is created by the fuel injection pump to increase the pressure, and this method cannot obtain sufficient injection pressure, and the cam There is a limit due to the Hertzian stress of the part, and the structure itself is complicated.

Further, the above fuel injection device disclosed in Japanese Utility Model Laid-Open No. 58-66164 uses the resultant force of a spring when the engine has a high load to increase the injection pressure with a certain time delay, delay the injection peak, and suddenly increase. While avoiding high pressure injection, the pressure rise in the combustion chamber due to combustion is suppressed.
It cannot solve the above problems.

An object of the present invention is to solve the above problems,
In a pressure-accumulation fuel injection device provided with a pressure accumulating chamber for temporarily accumulating fuel supply pressure in a pressurizing chamber supplied from a fuel injection pump and pressurized by a pressure boosting piston, a leak passage is connected to the pressure accumulating chamber, Even if the time from the start of fuel injection to ignition, that is, the ignition delay is greatly shortened due to the high temperature at the end of the compression stroke, the amount of fuel injection injected into the combustion chamber of the engine by the engine ignition timing is not reduced. ,
In order not to reduce premixed combustion immediately after engine ignition, in order to shorten the fuel injection period as much as possible, the valve closing pressure of the needle valve in the pressure accumulating chamber is quickly and early lowered than usual to always maintain a predetermined fuel injection. It is an object of the present invention to provide a pressure-accumulation fuel injection device that increases the pressure of the pressure accumulator to increase the injection rate in order to secure the amount and improves the engine performance according to the engine load.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, according to the present invention, a main body having an injection port for injecting fuel, a needle valve reciprocating in the main body for opening the injection port by fuel pressure, and a needle valve penetrating therethrough and accumulating fuel in the main body are formed. Accumulator chamber, a check valve that closes the accumulator chamber with a spring force and is slidable on the outer periphery of the needle valve, and a pressurizing piston that pressurizes the fuel to be supplied to the accumulator chamber. A pressure chamber, a pressure increasing mechanism for pressurizing the pressure increasing piston, a leak passage for leaking the fuel pressure in the pressure accumulating chamber through a gap on the outer circumference of the check valve, and a fuel injection from the injection port after the fuel pressure feeding period to the pressure accumulating chamber is completed. A pressure-accumulation fuel injection device, comprising: a solenoid valve that opens the leak passage in order to reduce the fuel pressure in the pressure accumulation chamber to a value equal to or lower than the valve closing pressure of the needle valve after a predetermined period has elapsed from the start of fuel injection. Related That.

Further, in this pressure-accumulation fuel injection device, the starting point of the leak operation of the fuel pressure in the pressure accumulator chamber due to the urging of the solenoid valve is adjusted according to the load of the engine.

Further, this pressure-accumulation fuel injection device is applied to an adiabatic engine.

[Action]

The pressure-accumulation fuel injection device according to the present invention is configured as described above, and operates as follows. That is, in this pressure-accumulation fuel injection device, a leak passage is connected to a pressure accumulation chamber that temporarily accumulates the fuel supply pressure in the pressurization chamber that is supplied from the fuel injection pump and is pressurized by the pressure boosting piston, and the solenoid is energized. Since the plunger that opens and closes the leak passage is provided, the pressure in the pressure accumulating chamber is leaked after the fuel pressure feeding period from the fuel injection pump to the pressure accumulating chamber ends and a predetermined period has elapsed from the start of fuel injection from the injection port to the combustion chamber. By doing so, it is possible to perform an operation of lowering the pressure in the accumulator below the valve closing pressure of the needle valve,
Even if the temperature at the end of the compression stroke of the engine becomes extremely high and the time from fuel injection to ignition is greatly shortened, the initial injection rate is increased by high-pressure injection to leak the pressure in the accumulator, Thereby, a predetermined amount of fuel can be injected into the combustion chamber of the engine in a short time.

〔Example〕

An embodiment of a pressure-accumulation fuel injection device according to the present invention will be described below in detail with reference to the drawings.

In FIG. 1, a pressure accumulating fuel injection device according to the present invention is indicated generally by the numeral 30. The pressure-accumulation fuel injection device 30 has a pressure-increasing mechanism 40 for pressurizing the pressurizing chamber 25 by the pressure-increasing piston 21 as compared with the pressure-accumulation fuel injection device 50 described with reference to FIG. And accumulator 5
Since they have the same configuration except that they have a pressure leak device for leaking the pressure of 1, the same parts are designated by the same reference numerals, and the description of those structures will be omitted.

As shown in FIG. 1, the pressure leak device includes a leak passage 16 communicating with the check valve outer peripheral gap 7, and a solenoid valve 35 provided between the leak passage 16 and the leak passage 37. A passage 17 is formed in the check valve seat 6 so as to communicate with the check valve outer peripheral gap 7. The passage 17 and the leak passage 16 communicate with each other. Therefore, the leak passage 16 is in constant communication with the pressure accumulating chamber 5. Further, the solenoid valve 35 includes a check ball 34 and a check ball 34.
It is composed of a spring 36 that constantly presses in the closing direction and a plunger 38 that moves the check ball 34 in the passage opening direction by the action of a solenoid. In this configuration, the check ball 34 acts to shut off the leak passage 16 and the leak passage 37 when the solenoid is not operating.

Next, with reference to FIG. 3, a pressure increasing type pressure accumulating fuel injection device 20 which is not provided with a pressure leak device will be described. The pressure increasing type pressure accumulating fuel injection device 20 is obtained by adding a pressure increasing mechanism 40 to the pressure accumulating fuel injection device 50 shown in FIG.

The pressure increasing mechanism 40 is provided with a fuel injection pump 18 that is driven separately from the fuel injection pump 8 for supplying the injected fuel. The fuel injection pumps 8 and 18 always have about 100-200 kg / cm ²
Is configured to operate at high pressure. The fuel injection pump 18 operates the pressure boosting piston 21. The pressure boosting piston 21 moves downward by the operation of the fuel injection pump 18. At this time, the inside of the pressurizing chamber 25 has an outer diameter dimension of the booster piston 21, that is, a surface area that receives the hydraulic pressure of the liquid from the fuel injection pump 18, and an outer diameter dimension of the plunger 28, that is, a surface area that faces the pressure chamber 25. Pressurized by the ratio.

For example, the area ratio is 10 and the pressure of the fuel injection pump 18 is
If the pressure is 100 to 200 kg / cm ² , the pressure in the pressure chamber 25 is 1000 to
It will be 2000 kg / cm ² . Therefore, the pressure in the pressure accumulating chamber 5 is also increased accordingly. In this case, in order to increase the pressure in the pressurizing chamber 25, pressure is applied to the pressurizing chamber 25 so that the check ball 26 arranged between the injection pipe 9 and the passage 13 closes the injection pipe 9. Move to (left side of the figure).

By the above operation, the pressurizing chamber 25 and the pressure accumulating chamber 5 are filled with the fuel whose pressure is increased to a high pressure. At this time, the solenoid 23 is actuated to move the plunger 23 to the left in the figure, and the check ball 22 to the left in the figure to move the injection pipe.
A passage 32 that closes 19 and opens the pressure chamber 31 to the atmosphere
The inside of the pressure chamber 31 acting on the pressure boosting piston 21 is opened to the atmosphere. As a result, the booster piston 21 moves upward due to the reaction force of the spring 24, and the plunger
28 also moves upward accordingly, the pressure in the pressurizing chamber 25 is reduced, and then the check ball 26 is released so that the injection pipe 9 and the passage 13 are brought into conduction.

Therefore, the pressurizing chamber 25 communicates with the fuel injection pump 8, and the fuel is supplied to the pressurizing chamber 25 by the fuel injection pump 8. Therefore, the pressure in the pressurizing chamber 25 becomes, for example, 100 kg / cm ² by the fuel injection pump 8, and the check valve 2
Is moved upward by the reaction force of the spring 4 and the pressure release of the pressurizing chamber 25 (in this case, for example, 100 kg / cm ² ) and pressed against the check valve seat 6. By contacting the check valve seat 6 with the protrusion 33 of the check valve 2, the pressurizing chamber 25, in other words, the through hole 14 of the check valve seat 6 and the check valve outer peripheral gap 7 are shut off. Therefore, the pressure accumulating chamber 5 becomes a sealed high pressure chamber.

At the same time, the needle valve 3 moves upward due to the reaction force of the spring 4 and the pressure release of the pressurizing chamber 25, and the fuel filled in the pressure accumulating chamber 5 is injected from the injection port 11 into the combustion chamber of the engine. By injecting the fuel, the pressure in the pressure accumulating chamber 5 decreases, and the fuel injection ends in a state where the reaction force of the spring 4 and the pressure in the pressure accumulating chamber 5 are balanced. By repeating the above operation, successive fuel injection into the combustion chamber of the engine is performed.

The pressure-accumulation fuel injection device 30 according to the present invention is characterized by, in particular, a pressure-increase type pressure-accumulation fuel injection device provided with the pressure leak device for leaking the pressure in the pressure accumulation chamber 5, as shown in FIG. There is.

The pressure increasing type pressure accumulating fuel injection device 30 according to the present invention is
Except that the pressure leak device is provided, the structure is the same as the structure of the pressure increasing type pressure accumulating fuel injection device 20, and therefore, the same parts of the pressure increasing mechanism 40 are designated by the same reference numerals. , Their explanations are omitted here.

The pressure-accumulation type pressure-accumulation fuel injection device 30 pressurizes a relatively low-pressure fuel with a pressure-increasing piston 21, sends the fuel into the pressure-accumulation chamber 5, and injects the fuel from the injection port 11 into the combustion chamber of the engine. It has the potential to generate a very high injection pressure. However, since there is a structural limit to reducing the volume of the pressure accumulating chamber 5, high pressure injection with a small injection amount cannot be performed, but since a pressure leak device consisting of the solenoid valve 35 is provided, the end of fuel injection is controlled. Can be, for example, 2000-3000 kg / cm ²
It is also possible to obtain the above injection pressure.

The pressure-accumulation fuel injection device 30 is configured as described above, and referring to FIG. 4, the basic structure of the pressure leak device in a state in which the pressure increasing chamber 25 is not increased by the pressure increasing piston 21. The operation will be described.

The graph of FIG. 4 shows the injection rate and the pressure in the pressure accumulating chamber in the pressure accumulating fuel injection device when the pressure increasing mechanism 40 is not taken into consideration. The abscissa plots the crank angle θ of the engine, and the ordinate plots the injection rate R and the pressure P in the pressure accumulating chamber 5.

In the graph of FIG. 4, solid curves a and b show the relationship of the pressure-accumulation fuel injection device when the pressure in the pressure accumulating chamber 5 leaks, and dotted curves c and d show the general pressure-accumulation fuel injection device. Shows the relationship. In this case, the injection amount Q determined by the injection rate R and the pressure P of the pressure accumulating chamber 5 is the same as that of the pressure accumulating fuel injection device 50, but the pressure P of the pressure accumulating chamber 5 is By leaking the pressure, the pressure is instantly reduced to a pressure P _s ′ that is equal to or lower than the valve closing pressure P _{s of the} needle valve 3 determined by the spring 4.

First, the pumping period of the fuel injection pump 8 ends at point E, then fuel is injected from the injection port 11 of the fuel injection nozzle, and after a predetermined period has elapsed, that is, at point F, the solenoid is turned on and the solenoid valve 35 is opened. Leak passage 16 and leak passage 37
To conduct. As a result, the fuel in the pressure accumulating chamber 5 instantly leaks through the check valve outer peripheral gap 7, the passage 17, the leak passage 16 and the leak passage 37. The pressure P in the pressure accumulating chamber 5 drops to a pressure P _s ′ that is equal to or lower than the valve closing pressure P _s of the needle valve 3 due to the instantaneous pressure leak from the pressure accumulating chamber 5. Further, the crank angle θ ₁ to the crank angle θ ₂ corresponds to the fuel injection period of the pressure accumulation type fuel injection device 10, and the crank angle θ ₁ to the crank angle θ ₃ corresponds to the fuel injection period of the general pressure accumulation type fuel injection device 50. Equivalent to.

Further, the injection amount Q of the pressure accumulation type fuel injection device when the pressure boosting mechanism 40 is not considered corresponds to the area enclosed by the curve b, and the fuel amount Q of the general pressure accumulation type fuel injection device 50 is enclosed by the curve d. Equivalent to the area. As described above, when the pressure in the pressure accumulating chamber 5 leaks, the needle valve 3 is pushed down together with the check valve 2 against the reaction force of the spring 4, the injection port 11 is closed, and the fuel injection is performed at the point G. finish.

Therefore, the injection period of the above pressure accumulation type fuel injection device is significantly shortened as compared with that of the conventional pressure accumulation type fuel injection device, the injection pressure can be greatly increased, and the pressure of the pressure accumulation chamber 5 is increased. It is possible to secure a predetermined fuel injection amount without being affected by.

Next, the pressure-accumulation fuel injection device 30 according to the present invention is provided with a pressure increasing mechanism 40, and the injection state thereof can obtain the above-mentioned effect, and mechanically increases the pressure in the pressurizing chamber 25. A fairly high pressure can be obtained without obstruction, which will be explained with reference to the graph shown in FIG.

Regarding this pressure-accumulation fuel injection device 30, when a general fuel injection pump and a pressure-accumulation fuel injection nozzle with a solenoid are combined, a governing mechanism for maximum rotational speed control and a control sleeve which are always provided in the general fuel injection pump. In addition, the fuel flow control system of the control rack and the fuel injection pump without the control of the timing advance angle are used.

In FIG. 2, the dotted line curve e shows the crank angle θ, the pressure P in the accumulator and the injection rate R at light load, the solid line curve f at medium load, and the chain line curve g at high load. .

First, the fuel is pumped to the pressure accumulating chamber 25 of the fuel injection pump 8 by
It ends at point E, crank angle θ ₆ . When the load is light, the solenoid valve 35 is operated at point J to operate the pressure leak device to leak the pressure in the pressure accumulating chamber 25, thereby ending the injection from the injection port 11 to the combustion chamber of the engine at the crank angle θ ₇ . Also, at medium load, point K
The solenoid valve 35 is operated to operate the pressure leak device to leak the pressure in the pressure accumulating chamber 25, thereby ending the injection from the injection port 11 into the combustion chamber of the engine at the crank angle θ ₈ . Further, at the time of high load, the solenoid valve 35 is operated at point M to operate the pressure leak device to leak the pressure in the pressure accumulator chamber 25, thereby ending the injection from the injection port 11 to the combustion chamber of the engine at the crank angle θ ₉ . To do.

Since this pressure-accumulation type fuel injection device can control the fuel injection as described above, the governing mechanism for controlling the maximum rotation speed, the control sleeve, the fuel flow rate control system for the control rack, etc. can be eliminated.

Further, a case where the fuel injection pump 8 causes a timing advance is described with reference to FIG. This is possible by controlling the time when the pressure in the pressure accumulating chamber 5 starts to rise. That is, the point T of the curve n shown by the solid line of the pressure accumulation chamber diagram is changed to the point S of the curve o shown by the dotted line to delay the start of pressure increase. In this case, the movement of the distance y from the point T to the point S can be achieved by opening the solenoid valve 35 to leak the fuel. The delay in closing the solenoid valve 35 delays the start of pressure increase (length y), and at the same time delays the start of injection (length t). In other words, when the engine speed is low, pressure increase starts from point S, and as the speed increases, the angle is advanced by gradually shifting from point S to point T. Although there is some deterioration in the injection characteristic, that is, there is an increase in the length x from the crank angle θ ₁₀ to the crank angle θ ₁₁ , but it is not so large and has no effect. Similarly, the injection start timing can be variably controlled by the load.

〔The invention's effect〕

The pressure-accumulation fuel injection device according to the present invention, which is configured as described above, has the following unique effects. That is, this pressure-accumulation fuel injection device connects the leak passage to the pressure-accumulation chamber that temporarily accumulates the fuel supply pressure in the pressurization chamber that is supplied from the fuel injection pump and is pressurized by the pressure boosting piston,
A plunger that can open and close the leak passage by urging a solenoid is arranged, and the fuel pressure feeding period to the pressure accumulating chamber ends,
Since the pressure in the pressure accumulating chamber was leaked after a lapse of a predetermined period from the start of fuel injection from the injection port to the combustion chamber, the temperature at the compression stroke end of the engine became high and the time from fuel injection to ignition was greatly reduced. Even if it is done, the initial injection rate can be increased by the high-pressure injection.

Further, since it has a function of leaking the pressure of the pressure accumulating chamber, it is possible to inject a predetermined amount of fuel into the combustion chamber of the engine in a short time.

In particular, since the pressure in the pressurizing chamber is increased, a desired and considerably high pressure can be obtained without any mechanical obstacle, which is extremely preferable as compared with a fuel injection pump that produces a high pressure.

Furthermore, the starting point of the pressure leak operation of the accumulator can be easily adjusted in various ways according to the load of the engine,
Further, since it can be operated so as to leak the pressure, it is possible to use, for example, a fuel injection pump that does not require a governing mechanism for controlling the maximum rotation speed, a fuel flow rate control system, or the like.

Further, this pressure-accumulation type fuel injection device is extremely preferable when applied to an adiabatic engine in which a cylinder liner, a cylinder head, a piston head and the like are made of a ceramic material. That is, in the case of an adiabatic engine made of a ceramic material, the temperature at the compression stroke end of the engine becomes extremely high and the time from the start of fuel injection to ignition, that is, the ignition delay is significantly shortened, as compared with a normal engine. Even if there is such a phenomenon, the function of lowering the valve closing pressure of the needle valve in the pressure accumulating chamber more quickly than usual so as not to reduce the premixed combustion immediately after the engine is ignited. It is possible to increase the injection rate by increasing the pressure in the pressure accumulating chamber as the pressure is shortened as much as possible, and always secure a predetermined fuel injection amount.

Further, this pressure-accumulation fuel injection device does not reduce the absolute amount of the fuel injection amount injected into the combustion chamber of the engine by the engine ignition timing, and always easily achieves a desired fuel injection flow rate according to the load of the engine. It can be adjusted and injected into the combustion chamber of the engine, improving the performance of the engine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pressure accumulation type fuel injection device according to the present invention, and FIG. 2 is a graph showing a relationship between a crank angle of the pressure accumulation type fuel injection device of FIG. 1, a pressure of a pressure accumulation chamber and an injection rate. FIG. 3 is a cross-sectional view showing an example of a pressure-accumulation type pressure-accumulation fuel injection device, and FIG. 4 is a crank angle when the pressure-increasing mechanism is not taken into consideration in the pressure-accumulation fuel injection device of FIG. FIG. 5 is a graph showing the relationship of the injection rate, FIG. 5 is a graph for explaining the timing advance angle of the fuel injection pump, FIG. 6 is a sectional view showing an example of a conventional pressure-accumulation fuel injection device, and FIG. 7 is FIG. Crank angle of the accumulator fuel injection device,
It is a graph which shows the pressure of a pressure storage chamber, and the relationship of an injection rate. 2 ... Check valve, 3 ... Needle valve, 4 ... Spring, 5 ... Accumulation chamber, 11 ... Injection port, 13 ... Passage, 15 ... Main body, 16, 37 ... Leak passage, 21 ... Increase Pressure piston, 25 ...
… Pressurization chamber, 30 …… accumulation type fuel injection device, 35 …… solenoid valve, 40 …… pressure increasing mechanism.

Claims (3)

[Claims] 1. A main body having an injection port for injecting fuel, a needle valve reciprocating in the main body for opening the injection port by fuel pressure, and a needle valve penetrating the needle valve and formed in the main body for accumulating fuel. Accumulator chamber, a check valve that closes the accumulator chamber with a spring force and is slidable on the outer periphery of the needle valve, and pressurization that is applied by a pressure-increasing piston to increase the fuel pressure supplied to the accumulator chamber. Chamber, a pressure increasing mechanism for pressurizing the pressure increasing piston, a leak passage for leaking fuel pressure in the pressure accumulating chamber through a gap on the outer circumference of the check valve, and fuel from the injection port after the fuel pressure feeding period to the pressure accumulating chamber is completed. A pressure-accumulation fuel injection device, comprising: a solenoid valve that opens the leak passage in order to reduce the fuel pressure in the pressure accumulation chamber to a value equal to or lower than the closing pressure of the needle valve after a predetermined period has elapsed from the start of injection. 2. The starting point of the leak operation of the fuel pressure in the pressure accumulating chamber due to the urging of the solenoid valve is adjusted according to the load of the engine. Accumulation type fuel injection device. 3. The pressure-accumulation fuel injection device according to claim 1 or 2, which is applied to an adiabatic engine.