JPH01142262A - Electromagnetic unit injector - Google Patents

Abstract

PURPOSE:To quickly open up a poppet valve, sharply stop fuel, and improve an injection characteristic by using a solenoid stator as an actuator for pulling down a poppet valve to open up a pressure passage connected to a plunger chamber. CONSTITUTION:An external-operating type plunger 1 feeds and discharges fuel through a plunger chamber 3a formed on one end thereof. A fuel injection valve 10 is provided on the lower part of the plunger chamber 3a. In this structure, the plunger chamber 3a is connected to a discharged fuel reservoir 3c which is connected to a low-pressure fuel source 24 or a drain fuel passage 3e by means of a feed-cum-pressure passage 3b. A pressure-balance type poppet valve 2 is provided to open/close the feed-cum-pressure passage 3b. An armature 13 is fixed to the poppet valve 2 and a first solenoid stator 12 which pulls up the poppet valve 2 to close the passage 3b and a second solenoid stater 19 which pulls down the poppet valve 2 to open up the passage 3b are provided on the armature 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] - The present invention relates to a unit injector which is a fuel injection device for a diesel engine, and more particularly to an electromagnetic unit injector having a solenoid-controlled, pressure-balanced poppet valve.

[Conventional technology]

The jerk-type unit injector is installed in each cylinder and driven by the engine by a cam (not shown) that operates the plunger, increases fuel pressure, opens the needle valve of the injection nozzle, and injects the fuel f into the engine combustion chamber. It is something. In this unit injector, the plunger is provided with a reed groove, and the injection amount is controlled by this reed groove and the oil supply/drain hole provided in the barrel, but the injection timing is determined by the shape of the reed and cannot be made variable. Have difficulty.

On the other hand, as seen in Japanese Patent Application Laid-open No. 58-152165, an electromagnetic unit injector has also been realized in which the injection amount and injection timing are made independent using a solenoid valve, and which is electronically controlled with high accuracy. An example of this is shown in the sectional view of FIG. 5, a schematic diagram of the mechanism is shown in FIGS. 6 to 8, and its operation is shown in FIG. FIG. 6 shows the state in which the plunger 1 is descending, and when the poppet valve 2 closes, the plunger chamber 3a is filled with fuel, which is pressurized and passes through the fuel passage 4a of the spacer 4 to the needle valve of the fuel nozzle 11. 10f: Open the valve and start fuel injection. Next, as shown in FIG. 7, when the poppet valve 2 opens, the plunger chamber 3 is pressurized by the plunger 1.
The fuel in a is pushed out to the drain passage 3b, and fuel injection ends. Further, as shown in FIG. 8, when the plunger 1 shifts from downward to upward, the supply pressure (usually 1 to 6 kg/cr) enters the plunger g3a through the fuel supply passage 3bi.
Fuel pressurized to IL flows in and fills the tank. This completes one cycle of fuel injection.

Details of these operations will be explained with reference to FIGS. 5 and 9, focusing on the solenoid valve.

(As shown in the figure, when the solenoid 12c is energized at time t, a magnetic flux is generated in the solenoid magnetic circuit, and an electromagnetic attraction force F is generated between the solenoid stator 12 and the armature 13.
c is generated, but the suction force is generated by the poppet valve spring 15.
The armature and poppet valve combination (13°22) will not move upward unless the load exceeds the 7t load.

At time t2, when the suction force becomes larger than the set load of the Sgeling 150, the poppet valve 2 rises as shown in Figure (C), and at time t5, the valve opening is closed. Thereafter, the driving voltage of the solenoid 12c is lowered to the voltage v2 necessary to keep the poppet valve 2 closed, as shown in the diagram (Q).

Now, the injection pressure Fi (as shown in the dJ diagram, starts to rise just before the point valve 2 closes)
At time t4 when the valve opening pressure becomes greater than 0, the needle valve 10
opens and fuel injection into the engine combustion chamber begins.

When the solenoid is de-energized at time t5, the magnetic flux generated in the magnetic circuit of the solenoid disappears, and the electromagnetic attractive force Fe acting between the solenoid stator 12 and armature 13 disappears. Therefore, the poppet valve 2 is lowered by the poppet valve spring 15, and the valve opening is opened. When the poppet valve 2 starts to open, the injection pressure stops increasing and starts decreasing. When the injection pressure further decreases and becomes smaller than the closing pressure of the needle valve 10 of the injection nozzle section 11,
The needle valve lO is closed and fuel injection into the engine combustion chamber is terminated.

[Problem that the invention seeks to solve]

However, Jin's conventional electromagnetic unit injector has the following drawbacks compared to the jerk type, which will be explained with reference to FIG.

FIG. 9 shows the injection pressures of the jerk-type and electromagnetic-type unit injectors with the same plunger diameter, the same plunger speed, and the same injection amount, and the lift of the injection nozzle needle valve 10 with a dashed line and a solid line, respectively. As is well known, high injection pressure and short injection amount are required to obtain good engine combustion performance with low fuel consumption and low smoke emissions. From this point, when comparing the jerk type and the conventional electromagnetic type, the electromagnetic type has a difference of ΔP (approximately 100 to 400 to 97 cm) than the jerk type.
), and the injection period is longer by ΔT (approximately 2° to 10° crank angle). That is, it can be seen that the electromagnetic type has significantly inferior engine combustion characteristics than the jerk type.

This is because the opening speed of the four-pot valve 2 is slow, which makes it difficult to cut off the end of fuel injection.

In FIG. 9, the opening time T3 (approximately 2 ms) of the pot valve 2
~7m5) is long, resulting in poor injection characteristics. What is related to the opening time of this poppet valve 2? This is the bed valve spring 15.

An object of the present invention is to provide an electromagnetic Shima-knit injector which has a poppet valve opening time T3 shorter than that of the conventional electromagnetic type and has injection characteristics superior to the jerk type.

[Means for solving problems]

In the electromagnetic unit injector of the first invention, the I lid valve 2! J: Function to close the pressure passage 3b and drain oil reservoir 3C that communicate with the plunger chamber 3a.The first solenoid stator is installed in the same manner as the conventional type, and the poppet valve 2 is lowered to open the passage. The poppet valve sgelling 15 with the function of
is installed on the opposite side of the first solenoid stator 12 via the armature 13, and the second solenoid stator 19 is provided with a function of opening the passage.

Furthermore, what about the electromagnetic unit injector of the second invention in addition to the first invention? -! ! It is characterized by having a spring 20 that maintains the open state of the shut valve 2.

[Effect]

Compared to the mounting load of a spring that can be installed in a well-balanced manner in a conventional electromagnetic unit injector, the electromagnetic force generated by the second solenoid stator can be strengthened to about 5 to 10 times the spring mounting load. As a result, the opening speed of the poppet valve 2 due to magnetic force can be increased compared to when using spring force.

Therefore, the opening time T of the poppet valve of the dual solenoid type electromagnetic unit injector according to the present invention is approximately 0.4 mg ~
At 1.2 ms, the injection pressure drop rate increases, and injection characteristics (injection pressure and injection period) similar to that of the Habo jerk type can be obtained.

〔Example〕

Embodiments of the electromagnetic unit injector according to the first invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is an assembled sectional view of the embodiment, and FIG. 2 is a detailed operational explanatory diagram of the unit injector shown in FIG. 1.

In FIG. 1, the main body housing 3 is provided with a plunger hole having a large inner diameter for slidably receiving the plunger 1, and a cylindrical hole having a larger inner diameter for slidably receiving the tappet 5.

Since the tappet 5 protrudes from one end of the main body housing 3, the tappet 5 and the sylanger 1 connected thereto can be reciprocated by a drive cam or logic arm (not shown) and a sylanger return spring 6. The tip of the syringer 1 and the syringer hole of the main body housing 3 form a syringe chamber 3a. Further, a lower end extension of the main body housing 3 is externally threaded and a nut 7 is screwed into it, and the injection nozzle assembly is fixed to the main body housing 3 by this nut 7.

Fuel is supplied, for example, from a fuel tank (not shown) through a supply ponder and a fuel nozzle to a cylinder (not shown) via a fuel supply passage in P to the fuel reservoir 24 in the lower part of the main body housing.
is supplied at relatively low pressure.

Further, the side portion of the main body housing 3 is provided with a debet valve shaft guide hole 3f, a lower circular hole 3g, and an annular conical valve seat 3h. A flat shoulder 31 is provided at the bottom of the lower circular hole 3g, and a lid 18 having a function of restricting the downward movement of the I-bet valve is fixed to the flat shoulder 31 with a screw 20.

The upper surface of the lid 18 forms a drain oil reservoir 3C together with the lower circular hole 3g. This drain oil reservoir 3C has a housing lower fuel reservoir 2.
4 through an in-housing supply passage 3d, and is further discharged through a drain passage 3e to a fuel tank (not shown). A communication hole 3k is provided between the fuel reservoir 3t on the side of the main body and the drain oil reservoir 3C, so that the pressure between the two oil reservoirs is equalized. The fuel reservoir 3t is for lubricating the poppet valve shaft 2.

One end of the passage 3b for entering and exiting the fuel into and out of the syringe chamber 3a opens a predetermined distance above the valve seat 3h of the poppet valve shaft guide hole 3f, and the other end slopes downward to form the plunger chamber 3a.
It opens at a. Further, a pin 16 for a blind plug is press-fitted into a guide hole 3j of the passage 3b. Drain oil sump 3C
Fuel flow between the passageway 3b and the passageway 3b is controlled by first and second solenoid actuated pressure balanced poppet valves 2.

The valve 2 has a conical valve seat surface and is formed of a head 2b and a valve stem 2C disposed upwardly. This valve stem portion 2C is provided with an annular groove 21 that communicates the passage 3b with the drain oil reservoir 3c during the opening/closing movement of the poppet valve 2. As shown in FIG. 1, an armature 13 is fastened and fixed to the upper end surface of the shaft portion of the poppet valve 2, and the armature 13 has a plurality of through holes 23 for allowing fuel to pass through when the armature moves. .

The first lenoid stator 12 is fastened to the main body housing 3 with screws 22 via the second lenoid P stator 19 and the lenoid spacer 14 . The first lenoid stator 12 is composed of a lenoid case 12a made of synthetic resin material, for example, and the second lenoid stator 19 is the same as the first lenoid stator 1.
It has the same internal structure as 2, and has a hole in the center for passing the poppet valve shaft 2c. Figure 1 shows the poppet valve in the closed state. A minimum air gap (approximately 0.05 to 0.3
) exists. What about the opposite situation, that is, the poppet valve is open? The lower end surface 2a of the pet valve is seated on the upper lid surface 18a, with the same minimum air gap provided between the second renoid stator 19 and the opposing working surfaces of the armature 130.

A pair of terminals (not shown) are connected to the first lenoid coil 12c and the second lenoid coil 19c,
This terminal can be connected to a power source via electrical wiring (not shown) through a fuel injection electronic control circuit (not shown), and in this way, the lunoid coils 12c, 19c can be connected to the operating conditions of the engine in a manner well known to those skilled in the art. The energization is controlled as a function.

Next, the operation of the first embodiment will be explained.

For engine operation, fuel from the fuel tank (not shown) is
The fuel is supplied at a predetermined relatively low pressure to the fuel reservoir 24 in the lower part of the housing via a fuel supply pipe (not shown) and a fuel supply passage (not shown) in the cylinder head. The fuel supplied to the fuel reservoir is supplied to the exhaust oil reservoir 3C through the supply passage 3d in the nosing, and is further drained to a fuel tank (not shown) through the drain passage 3e.

In FIG. 2, time t. -t, the first solenoid is not energized, but the second solenoid is PWM (Pu1s
(d) An average current 11 flows as shown in the figure, and an electromagnetic attraction force F is generated between the second renoid 19 and the armature 130.
2 occurs, the poppet valve 2 is held open. In this state, when the sylanger 1 starts its upward stroke, fuel flows from the drain oil reservoir 3C through the poppet valve annular groove 21 and the supply/pressure passage 3b into the silane gloss chamber 3a.

Time t. The groove energization of the second solenoid ends at ', and immediately after that, at time t, the first solenoid 12 starts to be energized as shown in Figure (a), and the second solenoid 19 and the armature 1
The electromagnetic attraction force F2 that had been working during the 30-minute period disappears, and instead an electromagnetic attraction force F is generated between the first renoid 12 and the armature 130. Therefore, the poppet valve 2 rises as shown in the figure, and at time t3, the poppet valve head 2b seats on the housing annular conical valve seat 3h. Immediately after this, the driving voltage required by the first solenoid 12 is sufficient to keep the poppet valve 2 closed, so that from vl to v2
It is lowered to Since the tappet 5 is pressed and the plunger 1 starts moving immediately before this, the fuel injection pressure starts to rise just before the poppet valve 2 closes, and from time t4 when it becomes higher than the opening pressure of the injection nozzle needle valve 10 (g ) As shown in the figure, the needle valve 10 opens and fuel injection into the engine combustion chamber begins.

When the second solenoid 19 is energized at time t5 and the first solenoid is de-energized at time t6, the second solenoid 19 is energized.
An electromagnetic attraction force F2 is generated between the lensoid 19 and the armature 13, and the first lensoid 12 and the armature 13
The electromagnetic attractive force F1 between 0 disappears. Therefore, the poppet valve 2 is lowered and the valve opening is opened. When the poppet valve 2 starts to open, the injection pressure stops increasing and starts decreasing. At time t7, when the injection pressure further decreases and becomes lower than the injection nozzle needle valve closing pressure, the needle valve 10 closes and fuel injection into the engine combustion chamber ends. Also poppet valve 2
When the second solenoid 190 is seated on the lid top surface 18a (time 1), the second solenoid 190 is de-energized. Due to the de-energization, the second current driving current starts to fall from the valve 2, but in order to maintain the poppet valve 2 in an open state, the current is energized again by the valve 2, so that the average current flows. This completes one cycle of operation, and the above cycle will be repeated thereafter.

The suction force F2 of the second solenoid 19 adopted in the embodiment of the first invention is 5 to 1
Since the value is about 0 times larger, the opening time T of poppet valve 2
3 is significantly reduced, the fuel exhaustion in the injection path can be improved, and the combustion efficiency of the engine can be improved. 3 and 4 show an embodiment of the second invention. The difference from the first invention is that the spring 20 is set in the direction of opening the poppet valve 2, which eliminates the need for electromagnetic force such as shoulder energization that always opens the poppet valve 2 in the first invention. However, a conventional structure as shown in FIG. 5 may be used.

〔Effect of the invention〕

According to the first invention described above, the second valve for opening the poppet valve is
The electromagnetic force generated by the solenoid stator 19 is much larger (approximately 5 to 10 times) than the force of the conventional electromagnetic poppet valve opening spring, so the poppet valve opening time T3 is approximately 0.4 ms. ~1.2m5 (conventional type: approx. 2m5)
Since the valve is opened in a very short time (from ms to 7 m5), the injection pressure can be rapidly lowered and the injection can be cut off easily. According to the first invention, when comparing the injection characteristics with the same plunger diameter, the same plunger speed, and the same injection amount, the electromagnetic unit injector of the first invention has an injection pressure of about 100 to 400 kg/kg compared to the conventional electromagnetic type.
cm higher, the crank angle is shorter by about 2° to 10° during the injection period, and good injection characteristics similar to those of the Habo jerk type can be obtained.

Furthermore, according to the second invention, in addition to the effects of the first invention, electromagnetic force by electric current or the like is not required so that the injection pump always opens the poppet valve in the first invention during the suction stroke, and the poppet valve is controlled. This has the advantage that it is simplified.

[Brief explanation of the drawing]

Figures 1 and 2 relate to the first invention, and are longitudinal sectional views of an electromagnetic unit injector, Figure 2 is an explanatory diagram of the operation of the unit injector of Figure 1, and Figures 3 and 4 relate to the second invention. Figure 3 corresponds to Figure 1, Figure 4 corresponds to Figure 2, Figures 5 to 9 are conventional examples, Figure 5 corresponds to Figure 1, and Figures 6 to 9 correspond to Figure 1.
8 is a schematic mechanical diagram of a conventional example, and FIG. 9 is an explanatory diagram of the operation of the unit injector of FIG. 5. 1...Externally actuated plunger, 2...Poppet valve,
3a1.・Silanger chamber, 3b...supply and pressure passage,
3C... Drain oil reservoir, 12... First solenoid stator, 13... Armature, 19... Second solenoid stator. Mystery Garlic-1) Mystery-w□-Hiruichi 1) ■Mon-Setsuhaichi)] Beya! Pulse ΔS

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Claims (2)

[Claims] (1) An externally actuated plunger (1) having the function of a reciprocating pump is provided, and fuel is discharged from a plunger chamber (3a) formed at one end of the plunger during a discharge stroke;
In an electromagnetic unit injector having a structure for sucking fuel into the plunger chamber during the suction stroke, and further provided with a fuel injection valve (10) below the plunger chamber;
A drain oil sump (3c) communicating with the plunger chamber (3a) and a low pressure fuel source (24) or a drain fuel passage (3e)
a supply and pressure passage (3b) that communicates with each other; a pressure balance poppet valve (2) that is provided between the supply and pressure passage and the drain oil reservoir and opens and closes the supply and pressure passage; and the poppet valve. The armature (13
); a first solenoid stator (12) provided on the opposite side of the armature to pull up the poppet valve to close the poppet valve; and a first solenoid stator (12) provided on the side opposite to the first solenoid stator via the armature An electromagnetic unit injector comprising a second solenoid stator (19) disposed to pull down the poppet valve to open it. (2) An externally actuated plunger (1) having the function of a reciprocating pump is provided, and the fuel is discharged from a plunger chamber (3a) formed at one end of the plunger during the discharge stroke;
In an electromagnetic unit injector having a structure for sucking fuel into the plunger chamber during the suction stroke, and further provided with a fuel injection valve (10) below the plunger chamber;
A drain oil reservoir (3c) that communicates with the plunger chamber (3a) and the low-pressure fuel source (24) or the drain fuel passage (3e); a pressure-balanced poppet valve (2) provided between the drain oil reservoir and opening and closing the supply/pressure passage; and an armature (13) fixed to the stem side end surface of the poppet valve.
a first solenoid stator (12) provided on a side of the armature opposite to the poppet valve for pulling up the poppet valve to close the poppet valve; and a second solenoid stator (19) for pulling down and opening the poppet valve;
) and a spring (20) for operating and releasing the spring (20) and maintaining that state.