JP2867622B2 - Fuel injection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for injecting fuel from an injection port.

[Conventional technology]

Conventionally, a combustion chamber in an engine is represented by a direct injection type and a sub chamber type.

The direct injection type combustion chamber achieves mixing of fuel and air by the injection energy of the fuel injected from the fuel injection nozzle and swirl and squish flow formed in the fuel chamber, thereby forming a combustible air-fuel mixture. However, the direct injection combustion chamber has a problem that intake efficiency is reduced due to swirl generation. In addition, the direct injection type combustion chamber has a problem that the structure of the fuel injection nozzle must be set to a high pressure and a high injection rate in order to increase the atomization and penetration of the fuel, and the structure becomes complicated. doing.

In addition, the sub-chamber combustion chamber achieves mixing of fuel oil droplets and air by a high swirl formed in the sub-chamber to form a combustible air-fuel mixture. The sub-chamber type combustion chamber has a problem in that a high swirl is formed in the sub-chamber, and the total heat transfer area of the main chamber and the sub-chamber increases to increase heat loss. Further, the sub-chamber combustion chamber has a problem that a throttle loss due to a communication hole communicating the main chamber and the sub-chamber increases.

In order to solve the above problem, a direct injection collision diffusion stratified charge system using a fuel impinging jet, so-called O
An engine having an SKA type combustion chamber is disclosed. OSKA
The type engine has a recess formed in the piston, that is, a collision portion protruding from the center of the bottom of the cavity, forms a concave combustion chamber around the collision portion, and collides the liquid fuel injected from the fuel injection nozzle with the collision portion. The fuel jet collides with the colliding portion to achieve diffusion and atomization of the fuel starting from the collision surface, thereby achieving good mixing of the fuel and air.

Examples of the above-mentioned fuel collision diffusion type engine include those disclosed in JP-A-63-120815, JP-A-62-139921, and JP-A-63-1710.

Further, as a pressure-increasing plunger type fuel injection device, there is one disclosed in Japanese Patent Application Laid-Open No. 60-256548. The pressure-increasing plunger type fuel injection device pressurizes fuel by using hydraulic pressure, is provided with two or more stages of plungers having different diameters, and supplies injection fuel to a stepped portion of the plunger via an on-off control valve. It is configured such that it can be supplied also to the gap between the cylinder and the cylinder.

[Problems to be solved by the invention]

By the way, in the engine using the piston having the OSKA type combustion chamber, the collision surface for colliding the fuel injected from the single-hole nozzle is a flat collision surface of the piston head.
The fuel collides with the collision surface and is diffused in a disk shape, but a squish flow into the combustion chamber is generated by the upward stroke of the piston, and the squish flow generates a good mixture of fuel and air in a thin film disk shape. To improve the combustion state.

However, in order to form a good outward disk flow in the above engine, the downward fuel jet velocity must be reduced. As a result, the disk flow also becomes slow, and sufficient light oil with good ignitability is required. There is a problem that the fuel is ignited before a proper air-fuel mixture is formed and the combustion deteriorates. Further, in the above engine, when the injection of fuel from the injection port is completed, a valve closing pressure acts on the plunger in the fuel injection device body and the closing period in which the needle valve closes the injection port by the plunger is delayed. When the later fuel is generated and the fuel of the latter is injected to the collision surface, there is a problem that a phenomenon of adhesion of carbon to the collision surface occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to reduce the downward fuel jet velocity so that a jet injected from an nozzle orifice collides with a collision surface to form a good and uniform disk-shaped fuel film. At the same time, in order to inject a predetermined amount of fuel in a short period of time, large oil droplets are injected from the injection port. In particular, a strong valve closing pressure is applied to the plunger in the fuel injection device main body at the end of fuel injection to set the needle valve. Forcibly closes, shortens the needle valve closing period, prevents fuel drooling, and realizes a high injection rate by configuring a large refueling passage area by eliminating pressure fluctuations in the high-pressure system. It is to provide a fuel injection device that performs.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a pressure boosting chamber to which fuel is supplied through a fuel supply passage formed in a nozzle body, a fuel pool to which fuel is supplied from the pressure boosting chamber, and a fuel pressure generated in the fuel pool. A needle valve that opens and closes a nozzle formed in the nozzle body, a plunger that shuts off fuel supply to the pressure intensifying chamber and increases the fuel pressure in the pressure intensifying chamber and the fuel reservoir, and pressurizes the plunger with hydraulic pressure. Pressurizing means for lowering the pressure to increase the fuel pressure in the pressure-increasing chamber, disposed between the needle valve and the plunger, acting on the needle valve in a direction to close the injection port, and A first spring set at a valve opening pressure to open the nozzle, a second spring provided at the plunger and set at a valve closing pressure at which the needle valve closes the nozzle, and a spring action of the second spring. Said A return spring for returning the needle valve forced closure ring for closing the nozzle hole by pressing the valve, and the plunger disposed between said plunger and said nozzle body, a fuel injection device comprising a.

The pressurizing means includes a pressurizing chamber for storing a liquid for urging the plunger with the liquid pressure, a leak passage having a throttle portion for allowing the liquid in the pressurizing chamber to escape, and the pressurizing chamber. And a piston that opens and closes a supply port through which the liquid flows into and out of the supply port by the hydraulic pressure.

Further, in this fuel injection device, a measuring piston for measuring a flow rate of the fuel reservoir provided in the nozzle body is provided in the nozzle body.

[Operation] Since the fuel injection device according to the present invention is configured as described above, if the second spring for which the valve closing pressure is set is adjusted to a strong set pressure, the plunger is set by the second spring having the set pressure. The needle valve is constantly pressurized via the valve, and when the fuel injection period ends, the fuel supply pressure rapidly decreases, and the needle valve can be forcibly closed by the spring force of the second spring at the set pressure. Therefore, the needle valve closing period can be shortened as compared with a normal fuel injection device, and the injection port is quickly and reliably closed, so that the phenomenon of fuel drop does not occur.

Then, the fuel supplied from the fuel supply passage to the fuel reservoir is injected from the injection port to form a bound liquid jet, and the liquid jet collides with the collision surface provided in the combustion chamber. Can be formed, and the jet caused by the later fuel can be eliminated. Therefore, the fuel film formed in the combustion chamber and the squish flow to the combustion chamber intersect, whereby good mixing of fuel and air can be realized.

〔Example〕

Hereinafter, an embodiment of a fuel injection device according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an embodiment of a fuel injection device according to the present invention, FIG. 2 is an explanatory view showing a state of the fuel injection device of FIG. 1 at the time of fuel injection, and FIG. FIG. 5 is an explanatory diagram showing a state of the fuel injection device at the end of fuel injection.

The fuel injection device according to the present invention is preferably applied to a fuel collision diffusion type engine. A fuel collision diffusion type engine includes, for example, a cylinder head fixed to a cylinder block, a piston reciprocating in a cylinder provided in the cylinder block, a combustion chamber formed in a piston head of the piston, and a substantially rising bottom from the center of the combustion chamber. It has a projection arranged in an inclined state, a collision plate having a flat collision surface provided on the projection, and a fuel injection nozzle having an injection port opened on the lower surface of the cylinder head. The fuel injection device according to the present invention can be incorporated as the fuel injection nozzle in the fuel collision diffusion engine.

As shown in the figure, this fuel injection device is composed of a large nozzle single-hole nozzle, and is attached to, for example, a cylinder head and has an injection port 1 opened to a combustion chamber. As shown in FIG. 1, this fuel injection device mainly includes a needle valve 2 for opening and closing an injection port 1 formed in a nozzle body 9, a plunger 8 for pressing the needle valve 2, and a pressurizing device for pressurizing the plunger 8. The pressure means is a pressurizing piston 10, a spring 11 (first spring) set between the needle valve 2 and the plunger 8, which is set at a valve opening pressure, is movably disposed with respect to the plunger 8, and has a valve closing pressure. A needle valve forced closing ring 31 for pressing the needle valve 2 by the spring action of a spring 12 (second spring) set to close the nozzle 1, and a plunger disposed between the plunger 8 and the nozzle body 9. 8 has a return spring 13 for returning.

In this fuel injection device, the needle valve 2 moves up and down a central hole 3 formed in a nozzle body 9. The nozzle body 9 has a fuel supply passage 4 through which fuel supplied from the fuel injection pump 5 passes, an annular fuel reservoir 7 communicating with the fuel supply passage 4, and a single injection hole 1. Also,
A tapered tip 6 for closing the injection port 1 is formed at the tip of the needle valve 2. Needle valve 2 always has spring 11
The nozzle 1 is closed by the spring force.

The fuel is sent from the fuel injection pump 5 to the fuel supply passage 4 through the pressurizing pump 26 and the regulator 27 by the operation of the fuel injection pump 5. The fuel supply passage 4 communicates with the pressure increasing chamber 30 by raising the plunger 8, and fuel is sent from the fuel supply passage 4 to the pressure increasing chamber 30 by communication between the fuel supply passage 4 and the pressure increasing chamber 30. The fuel in the pressure increasing chamber 30 is sent to the fuel reservoir 7 through the passage 34. Needle valve 2 has fuel reservoir 7
When the fuel is supplied to the fuel reservoir 7 and the fuel supply pressure of the fuel reservoir 7 is increased and increased, the fuel supply pressure is pushed up against the spring force of the spring 11, and the injection port 1 is opened.

In this fuel injection device, the fuel introduced into the pressure increasing chamber 30 is configured to be increased in pressure by the pressure increasing plunger 8. That is, the plunger 8 moves up and down in the center hole 33 formed in the nozzle body 9 to form the pressure increasing chamber 30 below the plunger 8 and the pressurizing chamber 22 above.
Further, the plunger 8 is fitted on the upper part of the needle valve 2 protruding into the pressure increasing chamber 30.

The pressurizing chamber 22 is supplied with a high-pressure liquid (fuel in the embodiment) from a supply port opened or closed by the pressurizing piston 10, that is, a passage 28. The high-pressure fuel supplied by the operation of the high-pressure pump 25 is supplied to the fuel reservoir 23 through a high-pressure passage 36 formed in the nozzle body 9. The fuel pressure from the high-pressure pump 25 is configured to be adjusted by the accumulator 24 communicating with the high-pressure passage 36. The high-pressure fuel supplied to the fuel reservoir 23 is lifted by the pressurizing piston 10 against the spring of the spring 17 to release the passage 28 so that the pressurizing chamber 22 is released.
Supplied to The high-pressure fuel supplied to the pressurizing chamber 22 passes through a leak passage 20 having a throttle 21 and a fuel supply passage 4.
Is in communication with

Further, the distal end portion 29 of the pressurizing piston 10 has a tapered surface located in the fuel reservoir 23 and closing the passage 28. In the middle of the pressure piston 10, a step with a tapered surface
A step 37 is located in the fuel reservoir 18 communicating with a fuel supply pressure passage 19 formed in the nozzle body 9 for applying a fuel supply pressure. Therefore, the upward movement of the pressurizing piston 10 causes the fuel to be supplied to the fuel reservoir 18 through the fuel supply pressure passage 19 by the operation of the fuel injection pump 5, and the high-pressure pump 25 operates to supply the high-pressure fuel to the fuel reservoir 23. As a result, the fuel pressure acts on the step portion 37 and the tip portion 29 of the pressure piston 10, and the pressure piston 10 rises against the spring force of the spring 17.

In particular, the fuel injection device according to the present invention
Of the needle valve 2. The plunger 8 has an outer peripheral portion 8 serving as a surface for receiving the return spring 13.
A, an intermediate portion 8B that receives the spring 12 and a central portion 8C that receives the spring 11.

The outer peripheral portion 8A of the plunger 8 is formed longer than the intermediate portion 8B and the central portion 8C to form a hollow portion 8D inside. Hollow part 8D
A needle valve forced closing ring 31 is arranged in the inside so as to be vertically movable. The spring 12 is disposed between the needle valve forced closing ring 31 and the intermediate portion 8B. In addition, central part 8C and needle valve 2
A spring 11 is disposed between the spring 11 and the upper end.
The spring 11 is adjusted to a weak spring force and the spring 12 is adjusted to a strong spring force.

The spring 12 adjusts the closing pressure of the needle valve 2 and presses the needle valve forced closing ring 31 downward. When the plunger 8 is lowered, the needle valve forced closing ring 31 is moved to the shoulder portion of the needle valve 2.
When it hits 2S, the needle valve 2 is lowered. The spring 11 adjusts the valve opening pressure of the needle valve 2.
Needle valve 2 by the fuel pressure acting on step member 2A of the tapered surface of
Raises the needle valve 2 against the spring force of the spring 11.
In the figure, the outer peripheral portion 8A, the intermediate portion 8B, and the central portion 8C constituting the plunger 8 are shown as separate bodies, but springs 11, 12 and a needle valve forced closing ring 31 are provided in the hollow portion of the plunger 8. After assembling, it is fixed to the integral structure with screws. The plunger 8 has an outer peripheral portion 8A, an intermediate portion 8B and a central portion 8C.
Moves up and down as one member.

Further, in this fuel injection device, a fuel metering chamber 16 is formed in the nozzle body 9 to communicate with the fuel reservoir 7 through a passage 35. In the fuel measuring chamber 16, a measuring piston 14 urged by a spring 15 is disposed. Therefore,
When the fuel in the fuel reservoir 7 is introduced into the fuel measuring chamber 16 through the passage 35, the metering piston 14 rises against the spring force of the spring 15, and the fuel in the fuel reservoir 7 is measured. .

Since the fuel injection device according to the present invention is configured as described above, it operates as follows.

In this fuel injection device, when the needle valve 2, the plunger 8 and the pressurizing piston 10 are located in the state shown in FIG.
The fuel is supplied to the fuel supply passage 4 through the regulator 26 and the fuel supply passage 4, and then sent from the fuel supply passage 4 to the fuel reservoir 7 through the pressure increasing chamber 30 and the passage 34. At the same time, the fuel supply pressure is supplied from the fuel injection pump 5 to the fuel reservoir 18 through the passage 19 by the operation of the fuel injection pump 5. Further, the high-pressure pump 25 operates to supply high-pressure fuel to the fuel reservoir 23 through the high-pressure passage 36. When fuel is supplied to the fuel reservoirs 18 and 23 and the fuel pressure rises, the pressurizing piston 10 rises against the spring force of the spring 17, and the pressurizing piston 10 opens the passage 28, and the high-pressure fuel The fuel is introduced into the pressurizing chamber 22 from the fuel reservoir 23.

Next, when the pressure in the pressurizing chamber 22 rises due to the supply of high-pressure fuel, the plunger 8 descends against the spring force of the return spring 13 as shown in FIG. The communication state of the pressure increasing chamber 30 is cut off.
At this time, the flow rate of fuel present in the fuel pool 7 is measured by the amount of rise of the measurement piston 14. When the pressure in the pressurizing chamber 22 further increases, the fuel pressure in the fuel reservoir 7 increases, and the fuel pressure acts on the step portion 2A of the tapered surface of the needle valve 2. The needle valve 2
Will open the nozzle 1. When spout 1 opens,
The fuel present in the fuel reservoir 7 and the pressure increasing chamber 30 is injected through the injection port 1, and the fuel is injected, whereby the pressure in the fuel reservoir 7 rapidly decreases. At this time, since the plunger 8 is constantly pressed downward by the high fuel pressure of the pressurizing chamber 22,
The fuel pressure in the fuel reservoir 7 decreases and the fuel in the pressure increasing chamber 30 decreases, so that the fuel pressure further decreases. When the plunger 8 is lowered, the needle valve compulsory closing ring 31 built in the plunger 8 is pressed downward by the spring force of the spring 12, and as shown in FIG. Abuts the shoulder 2S of the needle valve 2, the needle valve forced closing ring 31 forcibly lowers the needle valve 2 downward, and the needle valve 2 closes the injection port 1.

In this fuel injection device, when the fuel injection period ends, the supply of fuel from the fuel injection pump 5 stops and the supply of high-pressure fuel from the high-pressure pump 25 stops. When the high-pressure pump 25 stops, the fuel in the pressurizing chamber 22 is discharged from the leak passage 20 and the throttle section.
The fuel is leaked to the fuel supply passage 4 through 21, the pressure in the pressurizing chamber 22 decreases, the plunger 8 returns to the position shown in FIG. 1 by the spring force of the return spring 13, and waits for the next fuel injection timing. State.

As described above, in this fuel injection device, the needle valve 2 forcibly closes the injection port 1 by the spring force of the strong set pressure of the spring 12 when the plunger 8 ends the fuel injection. Therefore, if this fuel injection device is used, the needle valve closing period is shortened by the action of the plunger 8, and the occurrence of fuel drooling can be prevented. In addition, since there is no pressure fluctuation in the high-pressure system, the cross-sectional area of the fuel supply passages such as the fuel supply passage 4 and the passage 34 can be configured to be large, and the injection port 1 can be formed in a large injection hole accordingly. , A high injection rate can be realized.

When this fuel injection device is incorporated in a fuel collision diffusion type engine, it operates as follows. That is, in the fuel collision diffusion type engine, the squish flow flows into the combustion chamber by the rise of the piston. When the piston rises and fuel is injected from the injection port 1 by applying a valve-opening pressure to the needle valve 2 of the fuel injection device near the top dead center, the liquid fuel injected from the injection port 1 collides with the collision plate provided in the combustion chamber. And collides with the collision surface to form a disk-shaped fuel film along the collision surface and diffuses radially outward into the combustion chamber. In addition, in this fuel injection device, since the needle valve 2 is forcibly closed, the needle valve closing period is shortened, there is no dripping of the fuel, and the liquid fuel colliding with the collision surface forms a uniform disk-shaped fuel film. Therefore, the uniform disk-shaped fuel film and the strong squish flow of air into the combustion chamber intersect to promote the mixing of air and fuel, to form an optimal mixture, and then ignite and burn. , Combustion is promoted, and a good combustion state can be ensured. Therefore, the phenomenon that carbon adheres to the collision surface of the collision plate is prevented, and the collision surface can always maintain a flat surface, and a good disc-shaped fuel film is formed.

〔The invention's effect〕

Since the fuel injection device according to the present invention is configured as described above, if the second spring, which has set the valve closing pressure, is adjusted to a strong set pressure, if the fuel supply pressure decreases, the set pressure is immediately increased. The needle valve is pressurized by the spring force via the needle valve forced closing ring. Therefore, when the fuel injection period ends, the fuel supply pressure rapidly decreases, and the needle valve forcibly closes the injection port quickly and reliably by the spring of the second spring at the set pressure.

Therefore, if this fuel injection device is used, the needle valve closing period is shortened by the strong set pressure of the second spring via the needle valve forced closing ring, as compared with a normal fuel injection device, and the injection port becomes The needle valve closes quickly and securely, so that the phenomenon of fuel drooling does not occur.

In addition, since there is no pressure fluctuation in the high-pressure system, the flow path cross-sectional area of the fuel supply path such as the fuel supply path can be configured to be large, and accordingly the injection port can be formed in a large injection hole, and the high injection rate can be increased. Can be realized.

Therefore, when this fuel injection device is used in a fuel collision diffusion type engine, the fuel supplied from the fuel supply passage to the fuel reservoir is injected from the nozzle at a high injection rate to form a united liquid jet. When the liquid jet collides with the collision surface provided in the combustion chamber, a good disc-shaped fuel film can be formed in the combustion chamber, and the jet caused by fuel dripping can be eliminated. Therefore, the fuel film formed in the combustion chamber and the squish flow to the combustion chamber intersect with each other, so that good mixing of fuel and air can be realized.

Further, the pressurizing means includes a pressurizing chamber for storing a liquid for urging the plunger with a liquid pressure, a leak passage having a throttle portion for releasing the liquid in the pressurizing chamber, and the pressurizing chamber. Since the piston that opens and closes the supply port through which the liquid flows into the plunger with the liquid, the plunger can be satisfactorily pressurized, and the posture from the end of the fuel injection to the next fuel injection timing can be immediately adjusted.

Further, since the metering piston for measuring the flow rate of the fuel pool provided in the nozzle body is provided in the nozzle body, the fuel injection flow rate can be easily detected. By controlling the fuel injection device, the fuel injection flow rate into the combustion chamber can be easily adjusted according to the state of the combustion chamber, that is, the operating state of the engine.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a fuel injection device according to the present invention, FIG. 2 is an explanatory diagram showing a state of the fuel injection device of FIG. 1 at the time of fuel injection, and FIG. FIG. 4 is an explanatory diagram showing a state of the fuel injection device at the end of fuel injection. 1 ... nozzle, 2 ... needle valve, 2S ... shoulder, 3, 33 ... central hole, 4 ...
... Fuel supply passage, 5 ... Fuel injection pump, 7 ... Fuel reservoir, 8 ... Plunger, 9 ... Nozzle body, 10 ... Pressurizing piston, 11 ... Spring (set to valve opening pressure), 12 ... … Spring (set to valve closing pressure), 13 …… Return spring, 14…
... Measuring piston, 20 ... Leak passage, 21 ... Throttle section, 22 ...
… Pressurizing chamber, 28… Passageway (supply port) 30… Pressure increasing chamber, 31… Needle valve forced closing ring.

Continuing from the front page (72) Inventor Yoshio Sekiyama 8 Dosana, Fujisawa-shi, Kanagawa Prefecture, Isuzu Ceramics Research Institute Co., Ltd. 56) References: Japanese Utility Model Application 59-21079 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 61/10 F02M 61/20 F02M 47/00

Claims (3)

(57) [Claims] A pressure boosting chamber to which fuel is supplied through a fuel supply passage formed in a nozzle body; a fuel pool to which fuel is supplied from the pressure boosting chamber; and a fuel pressure generated in the fuel pool. A needle valve that opens and closes a nozzle formed in a nozzle body, a plunger that shuts off fuel supply to the pressure boosting chamber and increases the fuel pressure in the pressure boosting chamber and the fuel reservoir, and pressurizes the plunger with hydraulic pressure Pressurizing means for lowering the pressure of the fuel in the pressure-increasing chamber to increase the fuel pressure in the pressure-increasing chamber, disposed between the needle valve and the plunger and acting on the needle valve in a direction to close the injection port; A first spring set at a valve opening pressure for opening the nozzle, a second spring provided at the plunger and set at a valve closing pressure at which the needle valve closes the nozzle, and a spring action of the second spring. Needle valve Pressure and needle valve forced closure rings, and the plunger return spring for returning the plunger, which is arranged between the nozzle body, a fuel injection device comprising a for closing the injection port. 2. The pressurizing means includes: a pressurizing chamber for accommodating a liquid for urging the plunger to apply the liquid pressure; a leak passage having a throttle portion for releasing the liquid in the pressurizing chamber;
2. The fuel injection device according to claim 1, further comprising a piston that opens and closes a supply port through which the liquid flows into the pressurizing chamber by the hydraulic pressure. 3. 3. The fuel injection device according to claim 1, wherein a measuring piston for measuring a flow rate of the fuel reservoir provided on the nozzle body is provided on the nozzle body.