JPS6239677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a unit injector used in a diesel engine.

Generally speaking, unit injectors, unlike in-line fuel injection pumps or distribution-type fuel injection pumps, are installed directly on the cylinder head of a diesel engine without using a high-pressure injection pipe, and are installed directly on the diesel engine's cam. They have been configured to be driven by a shaft to inject fuel.

Typically, this type of unit injector has a plunger with a reed rotated by a control rack to vary the effective stroke of the plunger to meter the amount of fuel injected.

However, since such a unit injector is equipped with its own control rack, when installed in the cylinder head of a diesel engine, the structure around the cylinder head becomes extremely complex, and the unit - Considering the mounting position of the cam shaft, push rod, rocker arm, etc. as part of the injector's drive system, the mounting position of the unit injector is limited to an extremely narrow range, and the effective space in the cylinder head is limited. It was difficult to plan its use.

In addition, in recent years, a configuration has been developed in which fuel that has been regulated to a predetermined pressure is metered using a throttle and sent to a pump chamber, and then the high-pressure fuel drives a plunger to inject the fuel in the pump chamber. Unit injectors have been proposed that are equipped with a free piston type metering plunger in a plunger bore and configured to meter the fuel injected by the metering plunger. However, in the unit injector, which is metered by the throttle, when the fuel passes through the throttle and is sent to the pump chamber, air bubbles are generated, causing the injection amount to become unstable or the injection timing to be incorrect. In addition, a unit injector metered by a free piston type metering plunger has a complicated structure, and it is difficult to obtain the desired injection amount and timing. The component parts of the unit injector required extremely high machining accuracy.

An object of the present invention is to prevent the generation of air bubbles in a pump chamber, to properly measure the amount of fuel in the pump chamber, to obtain a desired fuel injection amount and injection timing, and to improve the engine performance of a diesel engine. An object of the present invention is to provide a unit injector used in a diesel engine which simplifies the structure around the cylinder head when it is attached to the cylinder head of the diesel engine.

In view of these problems, the unit injector used in the diesel engine of the present invention has a needle spindle bore having a valve seat and a jet nozzle, and a plunger bore connected to the fuel reservoir of the needle spindle bore. a nozzle needle fitted into the needle spindle bore so as to be seated in the valve seat by a needle spring;
A plunger that is arranged to be reciprocally slidable in the plunger bore so as to form a pump chamber at a position on the fuel reservoir side within the bore, and that includes a lead and a communication passage that connects the lead to the pump chamber. and is rotatably fitted to the distal end side of the plunger so as to form a slider bore concentrically widened with respect to the plunger in the plunger bore, and the plunger is slidable in a reciprocating manner. When a control sleeve is connected to the control sleeve by either a straight spline connection or a helical spline connection, and the control sleeve has a sleeve communication passage connected to the lead of the plunger. coupled to the inner circumferential surface of the slider bore by the other of spline coupling and helical spline coupling;
is reciprocably disposed within the slider bore,
A control slider that forms a hydraulic chamber at one end of the slider bore facing the pump chamber and a spring chamber at the other end of the slider bore facing away from the pump chamber, and a spring for the control slider.・Feed the slider control spring placed in the chamber and the sleeve communication path of its control sleeve.
The valve body includes a fuel passage formed in the valve body so as to communicate with the pump side, and an oil passage formed in the valve body so as to communicate the hydraulic chamber with the control oil pump side. It consists of

Hereinafter, preferred embodiments of the unit injector used in the diesel engine according to the present invention will be described with reference to the drawings.

Figures 1 and 2 show a specific example 1 of a unit injector used in a diesel engine of the present invention.
It shows 0.

The unit injector 10 is a valve
A needle spindle bore 19 having a seat 20 and a plurality of nozzles 21, 22, and a fuel reservoir 23 of the needle spindle bore 19.
a valve body 11 with a plunger bore 31 connected to the valve body 11 and a nozzle needle fitted into its needle spindle bore 19 so as to be seated in its valve seat 20 by a needle spring 50; 24 and its fuel reservoir 23 within its plunger bore 31.
A lead 34 and a communication passage 35 communicating the lead 34 with the pump chamber 33 are disposed in the plunger bore 31 so as to be reciprocally slidable so as to form a pump chamber 33 on the side.
A plunger 32 is rotatably fitted to the distal end side of the plunger 32 so as to form a slider bore 38 concentrically widened with respect to the plunger 32 in the plunger bore 31, and , a control sleeve 37 having a sleeve communication passage 39 that communicates with the lead 34 of the plunger 32 when the plunger 32 is slid back and forth into position;
The control sleeve 37 is connected with a straight spline to the outer peripheral surface thereof, and is connected with a helical spline to the inner peripheral surface of the slider bore 38 so as to be reciprocally movable within the slider bore 38. A control slider 42 having a hydraulic chamber 43 formed at one end of the slider bore 38 on the 33 side, and a spring chamber 44 formed at the other end of the slider bore 38 on the side remote from the pump chamber 33. and,
The slider control spring 45 disposed in the spring chamber 44 and the sleeve communication passage 39 of the control sleeve 37
The fuel passage 46 formed in the valve body 11 and the hydraulic chamber 43 can be connected to a control oil pump (not shown) so that the fuel passage 46 can be connected to a feed pump (not shown). like,
It is composed of an oil passage 48 formed in the valve body.

The valve body 11 has a nozzle fitting hole 18 at the lower end.
a nut 12 formed into a cylindrical shape with a nozzle 13 having a needle spindle bore 19 and a nozzle 13 fitted into the nut 12 so as to rest on the upper end surface of the nozzle 13;
and a needle spring guide 14 having a needle spring chamber 26 open at the top and disposed substantially coaxially with the needle spindle bore 19, and an opening in the needle spring chamber 26. A partition plate 15 is fitted into the nut 12 to close the end, and the nut 12 is fitted to secure the nozzle 13, needle spring guide 14, and partition plate 15 within the nut 12. A raised portion 54 is screwed into the upper end and has a slider bore 38 on the inside, and has a raised portion 54 on the inside of the lower end.
The slider guide 1 is integrally provided with a plunger bore 31 and has a plunger bore 31 inside its rising portion 54.
6 and a tube 55 that is screwed into the upper end of the slider guide 16 and extends so as to face the upper end surface of the rising portion 54 with a predetermined distance maintained.
It consists of 7.

Of course, the nozzle 13, needle spring guide 14 and partition plate 15 are provided with mutually connected fuel passages 25, 29 and 30, respectively, to connect the plunger bore 31 to the fuel of the needle spindle bore 19. Tamari 23
is in contact with.

Nozzle needle 24 is reciprocally slidably disposed in needle spindle bore 19 so as to be seated on valve seat 20 in nozzle 13 .

The nozzle needle 24 has a pin 28 at its upper end.
is integrally provided, and the pin 28 is connected to the needle.
Pin hole 2 formed at the lower end of the spring guide 14
7, the tip of the pin touches the spring seat 51 disposed within the needle spring chamber 26, and the needle spring 50 disposed within the needle spring chamber 26 always closes the valve seat. It is pressed to 20.

The plunger 32 cooperates with the inner circumferential surface of a control sleeve 37, which will be described later, to form a pump chamber 33 on the lower side of the plunger bore 31, that is, on the plate 15 side. - It is arranged in the bore 31 so that it can slide back and forth.

In other words, the plunger 32 is reciprocally slidably passed through the plunger guide 17 in the axial direction, and the inner peripheral surface of the control sleeve 37 and the riser on the inside at the lower end of the slider guide 16 The pump chamber 33 is formed inside the rising portion 54 in cooperation with the inner peripheral surface of the portion 54 .

Of course, the pump chamber 33 is connected to the above-mentioned fuel passage 2.
5, 29, 30 to the fuel reservoir 23 of its needle spindle bore 19.

Further, a lead 34 is formed in an inclined manner on the outer peripheral surface of the plunger 32 near the lower end, and a lead 34 is formed on the inner side of the plunger 32 near the lower end.
A communication passage 35 is formed that connects the pump chamber 4 to the pump chamber 33 thereof.

Furthermore, the plunger 32 has a follower part 36 at its upper end, and a valve spring 41 is arranged between the follower part 36 and the upper end surface of the plunger guide 17.

The control sleeve 37 is rotatably fitted onto the lower end side of the plunger 32.

Of course, the control sleeve 37 has its upper and lower end faces aligned with the plunger guide 17.
The tube 55 is sealed and sandwiched between the lower end surface of the tube 55 and the upper end surface of the rising portion 54 of the slider guide 16, and is fitted into the plunger 32 so that vertical movement is restricted. There is.

When the control sleeve 37 is fitted into the plunger 32 in this manner, the pump chamber 33 is formed on the lower side of the plunger 32, that is, inside the rising portion 54 thereof, as described above. 55, the control sleeve 37, and the raised portion 54 are each circumferentially covered by a ring-shaped space defined by the slider bore 38 thereof.

Further, the control sleeve 37 has one end opened at the upper end surface of the control sleeve 37 via the ring groove 40, and the other end opened at the inner circumferential surface at a substantially central position of the control sleeve 37. A sleeve communication path 39 is provided.

Of course, the other end of the sleeve communication path 39 is connected to the lead 34 of the plunger 32 when the plunger 32 slides back and forth and is placed in a predetermined position.
will be contacted.

In the state shown in FIG. 1, the control slider 42 has a control sleeve that forms a hydraulic chamber 43 on the lower side of the slider bore 38 and a spring chamber 44 on the upper side. Straight spline connection is made to the outer peripheral surface of the slider bore 3.
8 and is helically spline-coupled to the inner peripheral surface of the slider bore 38, and is reciprocatably disposed within the slider bore 38 thereof.

That is, a straight spline groove is formed on the outer peripheral surface of the control sleeve 37, and a helical spline groove is formed on the inner peripheral surface of the slider bore 38 of the slider guide 16. A straight spline that engages with the outer circumferential surface of the control sleeve 37 and a helical spline that engages with the inner circumferential surface of the slider bore 38 are formed on the inner and outer circumferential surfaces of the control slider 42, respectively. has been done.

Therefore, the control slider 42 is
Within the slider bore 38, the control slider 42 is allowed to reciprocate up and down with rotational motion, and in response to such movement of the control slider 42, the control slider 42 is connected to the control slider 42 by a straight spline. The control sleeve 37 rotates about its plunger 32 in the manner shown in FIG. 1 without moving up or down.

Further, as shown in FIG. 3, the control slider 42 is connected to the outer peripheral surface of the control sleeve 37 by a helical spline, and is further connected to the inner peripheral surface of the slider bore 38 by a straight spline. It may also be arranged reciprocally within the slider bore 38.

That is, in the control sleeve 37 and control slider 42 shown in FIG. A straight spline groove is formed on the inner peripheral surface, and the control slider 42
A helical spline that engages with the outer circumferential surface of the control sleeve 37 and a straight spline that engages with the inner circumferential surface of the slider bore 38 are formed on the inner and outer circumferential surfaces of the control sleeve 37, respectively.

Therefore, if the control sleeve 37 and the control slider 42 are configured in this way, the control slider 42 is allowed to reciprocate vertically with rotational movement within the slider bore 38. In response to the movement of the control slider 42, the control sleeve 37 connected to the control slider 42 by a helical spline does not move in the vertical direction, but remains in the state shown in FIG. It rotates around its plunger 32.

The slider control spring 45 is
It is located within the spring chamber 44 and urges the control slider 42 downwardly.

The fuel passage 46 is formed in the valve body 11 so as to connect the sleeve communication passage 39 of the control sleeve 37 to a feed pump (not shown).

That is, the fuel passage 46 has one end, in other words, the fuel port 47 connected to the valve body 11.
The sleeve communication path 3 is opened at the upper end and on one side of the plunger guide 17, and the other end is connected to the upper end surface of the control sleeve 37.
The plunger guide 17 is formed so as to communicate with a phosphor groove 40 that is communicated with the plunger guide 9 .

Of course, since the other end of the fuel passage 46 is connected to the ring groove 40 as described above,
Even as the control sleeve 37 rotates around the plunger 32, the fuel passage 46
is always in communication with the sleeve communication passage 39 of its control sleeve 37.

The oil passage 48 is formed in the valve body 11 so as to communicate the hydraulic chamber 43 with a control oil pump (not shown).

That is, the oil passage 48 has one end, in other words, a hydraulic port 49 opened above and on one side of the plunger guide 17 of the valve body 11, and the other end communicates with the hydraulic chamber 43. The plunger guide 17 and slider guide 16 of the valve body 11 are formed as shown in FIG.

Furthermore, in the plunger guide 17 described above,
At a position opposite the fuel passage 46, one end, ie, a spill port 53, is opened above the plunger guide 17 and on the other side, and the other end is connected to the ring groove 40. , a spill communication path 52 is formed.

The unit injector 10 configured as described above has its nozzles 21 and 22 housed in a combustion chamber in the cylinder head of a diesel engine (not shown), and the follower portion 36 of its plunger 32 in the cylinder head of a diesel engine (not shown). It is attached to the cylinder head of the engine in such a way that it contacts the cam surface of the camshaft.

In the unit injector 10 thus mounted on the cylinder head, the fuel port 47 of its fuel passage 46 is connected to the supply port of the feed pump via a fuel line (not shown), and The spill port 53 of the spill communication passage 52 is connected to a fuel return pipe (not shown).
It is connected to the return side of a fuel tank (not shown) via.

Further, a hydraulic port 49 of the oil passage 48 in the unit injector 10 is connected to a supply port of a control oil pump (not shown) via a hydraulic pipe (not shown).

The control oil pump is configured much like a hydraulic governor used in existing diesel engines, i.e., the control oil pump is configured to control the amount of accelerator pedal depression and pressure of the vehicle equipped with the diesel engine. Hydraulic pressure is generated according to the number of rotations of the diesel engine, and the hydraulic pressure is sent to the hydraulic port 49.

Next, to explain the operation of the above-mentioned unit injector 10, first, fuel from the feed pump is sent to the fuel port 47, and when the plunger 32 slides back and forth due to the rotation of the cam shaft, the plunger At a predetermined position in the sliding stroke range of 32, the control sleeve 3
The sleeve communication passage 39 of No. 7 is connected to the lead 34 of the plunger 32, and fuel is sent into the pump chamber 33 and metered. It is controlled by pressure oil delivered to the hydraulic port 49 of the unit injector 10.

That is, when pressure oil from the control oil pump is sent to the hydraulic chamber 43 of the unit injector 10, the control slider 42 is always balanced against the slider control spring 45 by the pressure oil. , slides vertically within the slider guide 16, and as the control slider 42 moves, the control sleeve 37 rotates around its plunger 32.

Therefore, the relative position of the sleeve communication passage 39 of the control sleeve 37 and the lead 34 of the plunger 32 is changed, and the communication between the sleeve communication passage 39 and the lead 34 causes the pump chamber to be opened. The fuel is metered within 33.

Of course, as described above, the pressure oil enters the hydraulic chamber 43.
, its control slider 42
slides upward while rotating in the direction of the arrow shown in FIG.
and its relative position with the lead 34 is changed,
Moreover, the relative positional deviation, that is, the rotation angle of the control sleeve 37 is determined according to the force of the pressure oil sent to the hydraulic chamber 43.

The fuel metered in the pump chamber 33 in this way is compressed in the pump chamber 33 by the plunger 32 being pushed in by the cam shaft, and the compressed fuel is transferred to the fuel passage 3.
0, 29, 25 to the fuel sump 23 of the needle spindle bore 19.

Further, when the plunger 32 is pushed in and the fuel pressure in the fuel reservoir 23 reaches a predetermined pressure, the nozzle needle 24
is lifted against the needle spring 50, and a predetermined amount of fuel is injected in the form of a mist under high pressure from the nozzles 21 and 22.

According to the invention configured as described above, the control slider is reciprocated with rotational motion by the pressure oil from the control oil pump, and further, the control sleeve is moved in accordance with the movement of the control slider. By rotating the control sleeve and changing the relative position of the sleeve communication passage and the plunger lead, the metering of fuel in the pump chamber of the unit injector is controlled by the pressure oil from the control oil pump. In particular, when metering the fuel, the communication between the sleeve communication path and the lead prevents the fuel from being excessively throttled and prevents the generation of bubbles in the pump chamber. , the desired fuel injection amount and injection timing are obtained, improving the engine performance of the diesel engine, and the diesel engine does not have the control rack used for fuel metering in existing unit injectors. When the cylinder head is attached to the cylinder head, the structure around the cylinder head is simplified and becomes extremely practical.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a specific example of a unit injector used in a diesel engine of the present invention, and FIG. 2 is a perspective view showing a means for connecting the control sleeve and control slider in the unit injector of FIG. 1. diagram, and
Figure 3 shows the control system in the unit injector used in the diesel engine of this invention.
FIG. 7 is a perspective view showing other coupling means of the sleeve and control slider; 10...Units used in diesel engines
Injector, 11... Valve body, 19... Needle spindle bore, 20... Valve seat,
21, 22...Nozzle port, 23...Fuel reservoir, 24...Nozzle needle, 31...Plunger bore, 32...
Plunger, 33...Pump chamber, 34...Lead, 3
5...Communication path, 37...Control sleeve, 3
8...Slider bore, 39...Sleeve communication path, 4
2...Control slider, 43...Hydraulic chamber, 4
4...Spring chamber, 45...Slider control spring, 46...Fuel passage, 48
...Oil passage, 50...Needle spring.

Claims (1)

[Claims] 1. A needle spindle bore having a valve seat and an orifice, and the needle
A valve body with a plunger bore connected to the fuel reservoir in the spindle bore and a needle spring
A nozzle needle fitted into the needle spindle bore so as to sit on the seat, and a nozzle needle fitted into the plunger bore so as to form a pump chamber at a position on the fuel reservoir side within the plunger bore. A plunger arranged to be reciprocatingly slidable and having a lead and a communication path connecting the lead to the pump chamber, and a slider bore formed in the plunger bore and expanded concentrically with respect to the plunger. a control sleeve rotatably fitted to the distal end side of the plunger and having a sleeve communication path connected to a lead of the plunger when the plunger is slid back and forth; and a straight spline. bond and helical
The slider is coupled to the control sleeve by one of the spline couplings and to the inner peripheral surface of the slider bore by the other of the straight spline coupling and helical spline coupling.・The slider bore is arranged so as to be able to reciprocate within the bore, and has a hydraulic chamber at one end of the slider bore facing the pump chamber and a spring chamber at the other end of the slider bore facing away from the pump chamber. a control slider forming a control slider, a slider control spring disposed in the spring chamber thereof, and a control sleeve formed in the valve body so as to connect the sleeve communication passage of the control sleeve to the feed pump side. A unit used in a diesel engine that includes a fuel passage formed in the valve body and an oil passage formed in the valve body so that the oil pressure chamber can be connected to the control oil pump side.
Injector.