JPS59153967A - Fuel injection unit for compression ignition engine - Google Patents

Abstract

PURPOSE:To increase the fuel injection pressure by performing the plunger drive of an injection pump with a crank mechanism. CONSTITUTION:An accumulator fuel injection unit 4 is constituted with a fuel injection pump 4A and an accumulator fuel injection valve 48 connected to the pump tip and provided with a fuel injection valve 4b. A plunger 38 is rotatably connected to one end of a cross bed 37 and a pin 38 is fixed to the other end. The pin 38 is inserted into a link 39, which is connected to a cam shaft 50 through a rocker arm 43 and a connecting rod 49. Accordingly, the plunger driving system is a positive motive type not requiring a spring, and there is no fear of the breakage caused by the stress and surging of the spring, thus a large pump head can be available.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for a compression ignition engine.

The conventionally known jerk'i (or unit injector injection force 1α) is the cam 4qI+-0
With one rotation, the plunger is pushed up, pressurizes and discharges fuel, and injects it into the combustion chamber of the engine through a nozzle. However, in these structures, the injection pressure and the f11 ejection rate are both low at low speeds of the engine, and inevitably increase at high speeds, which reduces performance and thermal efficiency at low speeds.

Therefore, in order to further improve the thermal efficiency over the entire rotation range and load range, it is necessary to increase the injection pressure and injection rate to improve the combustion efficiency, shorten the fuel injection period, and increase the degree of isovolume. In the prior art described ifJ, it is difficult to increase this injection pressure and increase the ejection rate.

Therefore, in order to solve this problem, Mlf type fuel injection devices have been developed, and although some of them have reached the practical level, they have not yet reached the point of widespread use.

First, the pressure accumulation type fuel injection device that does not use a pressure device has a low price, but like the jerk type mentioned above, the surface pressure between the cam and the roller is low. There is a limit to this, and it is difficult to increase the injection pressure to 100 atmospheres. In addition, the pressure accumulating fuel injection device can inject high-pressure fuel in a short period of time using the electronic opening side 1, but due to the removal of pus, it is expensive and has low reliability, which hinders its widespread use. are doing.

In this way, in conventionally known fuel injection devices, the plunger is driven by a cam and a roller follower without exception.
The contact between the cam and the roller is a line contact, and as the injection pressure increases, the Hertzian stress in the scarlet contact area affects the contact between the cam and the roller due to surface pressure fatigue [7I'I eventually peels off, lose its functionality.

This has hindered the development of high-pressure, high-injection-rate injection devices.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-pressure fuel injection system M capable of dramatically increasing the fuel injection pressure, which is limited by the Hertzian stress between the cam and the roller in the prior art described above.

Still another object of the present invention is to provide a fuel injection system that can be easily adapted to not only low and medium speed engines but also high speed diesel engines.

The present invention is characterized by a pressure accumulating type fuel in which fuel injection is started by a pressure drop in fuel path J16 from a non-pressure boosting type fuel injection pump to a pressure accumulating chamber, and fuel injection is terminated by a pressure drop in the pressure accumulating chamber. In the injection device, the plunger of the injection pump is driven by a hydrolubricated crank mechanism.

Embodiments of the present invention will be explained based on the drawings.

In Fig. 1, a piston 2 is inserted into a cylinder block 1, and an injection port of a pressure accumulation type fuel injection device 4 installed in a cylinder head 3 is open and located on the top surface of this cylinder block. There is.

Here, we will discuss the specific configuration of the pressure accumulation type fuel injection device 4 in the second section.
This will be explained with reference to the figures.

This device 4 is composed of a fuel injection pump 4A and an accumulator fuel injection valve 4B connected to the tip of the pump and provided with a reed fuel injection valve 4b.

Therefore, first of all, to explain the structure of the pressure accumulator fuel injection valve 4B, a screw at the upper end of a nut 6 is screwed into a screw cut into the lower end of the outer frame 5 of the injection pump 4A, and Control valve body 7 from above. Spacer 8. The pressure accumulator cylinder 9, the spacer 10 and the needle valve body 11 that constitute the fuel injection valve 4b are housed in a strongly compressed state.

An injection port 11a is formed at the tip of the needle valve body 11, and opening and closing of this injection port is controlled by a valve seat on the inner wall of the tip of the valve body and a valve face at the tip of the needle valve 12.

The large diameter part of the upper half of the needle valve 12 fits into the needle valve body 11 so as to be able to move up and down, and a spring holder 13 is fixed to the upper end of this large diameter part. is landing.

A fuel passage 11a is provided within the needle valve body 11, and this passage communicates with a space 15 around the outer circumference of the small diameter portion of the needle valve.

A fuel passage 10a is also formed in the spacer 10,
The upper part of this passage communicates with the compression chamber 16 in the lip pressure tube 9, and the lower part communicates with the passage 11a.

The spacer 8 has a fuel passage 8a communicating with the atmospheric pressure side of the needle valve 12 and a passage sb communicating with the pressure accumulation chamber 16.

8c is formed, and the F end of this spacer presses against the spring 14.

The fuel passage 8a includes a fuel passage 7a of the white-control valve body 7 and a fuel passage 7b branching from this passage 7a.

7c, and furthermore, the passage 7a is connected to the fuel 1+passage 5 of the outer frame 5.
It is connected to a. and fuel passages 8a, 7a.

Reference numeral 7b communicates with the atmospheric pressure side of the needle valve 12, and an end-of-injection control valve 17 is provided between this passage and a fuel passage 8b communicating with the pressure accumulator 16. lli injection end control valve 17
The large diameter portion 0 is fitted into the control valve body 7 in a manner that allows the weight to be freely adjusted, and the face 17a of this control valve is as follows.
It is held down by a compression spring 18 inserted into the outer frame 5, and serves as a stopper for the spacer 7I. Further, when the valve face 17a shown in FIG.

Between the fuel passages 7c and 8c, a check valve 20 for blocking the backflow of fuel from the passage 8C to 7c is connected to the control valve body 7 by a compression spring 19 housed in the spacer 8.
It is attached to. Fuel leakage from the joint surface between the split Ill valve body 7 and the injection end control valve 17 is caused by the injection pump 4.
The fuel is returned to the atmospheric pressure side through a fuel return passage 22 communicating with the spill port 21 in A.

Next, the internal structure of the fuel injection pump 4A will be explained. The suction-back valve 24, which is loosely fitted into the suction-back valve body 23 and prevents leakage, has a function as a check valve with a compression spring 25, and a stopper. 26 regulates the bento.

A plunger 28 is slidably inserted into the barrel 27! It is shi.

In the barrel 27, between the fuel inlet 29 and the fuel passage 3o, there is a check valve 31 which performs a check action by a spring, and prevents the fuel from flowing back from this passage to the inlet. A spill port 21 is located in the middle of the barrel 27, and a fuel return passage 22 prevents the generation of back pressure on the control valve 17, and fuel from these is passed through a fuel return port 32 to a fuel tank (not shown) or to a fuel tank (not shown). will be returned to fuel population 29. Between the fuel population 29 and the tF return port 32 or between the fuel return port and the atmosphere 1d
: It is necessary to properly prevent leakage by using 01J ring or the like.

Note that the barrel 27 and the suction-back valve body 23 are attached to the outer frame 5 with screws 33.

The plunger 28, which has exactly the same structure as the Bosch type, has a passage 28a inside, and the cutout surface 28b of the positive lead ends oil feeding when it communicates with the spill port 21, and the amount of oil discharged by the lift height of the plunger thereafter. is discharged from the fuel return port 32 via the spill port.

A rack 34a is carved into a part of the adjustment rod 34 which is rotatably supported on the outer frame 5, and this rack is connected to the plunger 28.
established in The teeth mesh with the wheel 28c.

Incidentally, the position of the adjusting rods 3 and 4 is determined by the balance between the force of the spring 35 and the hydraulic pressure from the hydraulic inlet 36, and the injection timing is determined.

The configuration of the pressure accumulation type fuel injection device 4 has been described above, and next, the configuration of the manual mechanism of the plunger 28 of this device will be explained.

In FIG. 3, a cross bed 37 that is vertically movably fitted into the hollow portion at the upper end of the outer frame 5 has a plunger 28 rotatably connected to one end, and a pin 38 at the other end.
is firmly attached. The lower end of the link 39 is rotatably connected to the pin 38 via a bush 40.1. The upper end of this link is rotatably connected to the left end of a rocker arm 43 via a bush 41 and a pin 42. The rocker arm 43 is connected via a bushing 44 fixed to it.
It rotatably engages with a rocker @ 46 fixed to a bracket 45 projecting from the cylinder head 3 (FIG. 1), and a pin 47 is fixed to the other end of the rocker arm. The upper end of a connecting rod 49 is rotatably connected to the pin 47 via a bush 48, and the lower end of this connecting rod is aligned with the axis of a camshaft 50 for operating the intake and exhaust valves, as shown in the first figure. It is rotatable via a crank pin 51 formed eccentrically and bearings sz, 5a. The bearings 52 and 53 are secured to the connecting rod 49 by tightening the bearing cap 54 with a bolt 55.

Next, the operation of the present invention will be explained.

The amount of fuel to be injected from the metering oil pump passes through the fuel port 29, the check valve 31, and the passage 30, and then flows into the barrel 29.
is supplied to the chamber within.

As the plunger 28 descends from the top dead center, the check valve 31 closes, the pressure inside the chamber increases by 1, and the suction valve 24
Push down and open fuel passages 5a, 7a, '8a.
is pumped to.

At this time, the end-of-injection control valve 17 is pressed down by the spring 18, and its valve face 17a is pressed down as shown in Figure 2A.
has moved past the valve seat 7d of the control valve body 7, and the valve is open.

The fuel fed to the passage 7a is fed under pressure into the pressure accumulation chamber 16 through the passage 7b, the injection path control valve 17, and the passage 8b. As is well known, fuel oil is an elastic fluid, and its volume decreases in proportion to the pressure F series and is stored in the pressure accumulation chamber 16. When the pressure in the pressure accumulation chamber 16 reaches, for example, 1000 atmospheres,
The injection material control valve 17 is pushed up against the pushing down force of the spring 18, so that the valve seat 7d and the valve face 17
a and closes, and passages 7b and 8b are cut off.

From this point on, the check valve 20 opens, and the fuel that has passed through the passages 7C and 8c is further compressed to a high pressure and stored in the pressure accumulating chamber 16, and this pressure is transferred to the fuel passage 10a.

11a to the lower part of the needle valve 12.

The inside of the passage 8a is also at high pressure like the inside of the pressure storage chamber 16, and this pressure is applied to the upper side of the large diameter portion of the needle valve. In this state, spring 1
4 Force + Pressure The valve face at the end is strongly pressed against the valve seat, and the fuel flows into the injection port 11.
There is no leakage from a.

As the engine rotates, the plunger 28 is further pushed down, and the design is such that the maximum pressure on the suppression side of the injection system reaches, for example, 2000 atmospheres at the maximum fuel injection amount.

At this time, the passage between the passage 28a and the spill port 21 is opened by the notch 28b of the plunger 28. The fuel oil on the high pressure side passes through the passage 28a, passes through the spill port 21, and overflows into the fuel return port 32.

At this time, the suction valve 24 closes, and its suction action rapidly reduces the pressure in the passages 5a, 7a, and 8a.
The pressure pushing down the large diameter portion of the needle valve 8 also disappears.

On the other hand, the high-pressure fuel in the pressure accumulation chamber 16 is pumped up by the check valve 20, and the injection material control valve 17 is pushed up because the pressure is, for example, 1000 atmospheres or more, and the valve face and valve seat continue to close, and the fuel flows through the passage 5a, There is no backflow into 7a and 8a.

At this time, (plane b of the needle valve large diameter part (-area of the needle valve small diameter part)
× The force of pressure pushes up the needle valve 12 against the sword of the spring 14, and the space between the valve face and the valve seat (ZL opens, through which the fuel is injected into the engine combustion chamber from the injection ports 1 and 1g. As the fuel injection progresses, the pressure of the fuel compressed in the pressure accumulation chamber 16 continues to decrease, and when it finally decreases to, for example, 1000 atmospheres, the spring 18 closes the injection path 9 control valve 17.
is pushed down, the valve opens as shown in Figure 2A, and the pressure accumulator 1
The fuel in 6 flows back through passages 8bEl and 7b into passages 7a and 8a.

At this time, as described above, the suction return valve 24 is in a closed state, and the fuel does not overflow to the spill port 21, and the fuel passage 8a
Naturally, the pressure becomes the same as that in the pressure accumulation chamber 16, and this pressure is applied to the upper part of the large diameter portion of the needle valve, and the needle valve 12 is rapidly closed.

In this way, the present invention, with the help of the injection path 9 control valve 17,
At the same time as this valve opens, the same pressure is applied above and below the needle valve 12, and the needle valve is accelerated toward the valve seat by the force of the spring 14 without being affected by the pressure inside the pressure accumulation chamber 16. However, it is possible to dramatically increase the valve closing speed, shorten the fuel direct injection period, and achieve a high injection rate.

Therefore, the driving means for the plunger 28 will be explained. In FIG. 1, the crank pin 51 is rotated by the rotation of the camshaft 50.
The connecting rod 49 is reciprocated in the vertical direction, and the rocker arm 43 follows the movement of its small end and swings about the rocker shaft 46'f. Therefore, rocker arm 43
The swing moves the crosshead 37 up and down via the link 39, and drives the plunger 28 rotatably connected thereto.

The rotation of the camshaft 50 causes the crank pin 51 to rotate from the bottom dead center, and while moving toward the above point, the connecting rod 4.9 moves upward, and this movement is transmitted through the pin 47 to the rocker arm 4.
3, and the rocker arm 43 is rotated counterclockwise around the rocker shaft 46.

Therefore, the pin 42 at the other end of the rocker arm 43 moves downward and the link 39. Crosshead 37 via pin 38
Push down.

The plunger 28 connected to the cross-\rad 3f moves downward and increases the pressure of the fuel in the barrel 27, opens the suction-back valve 24, and pumps the fuel into the fuel passage 8a.

This pressure is applied to the upper side of needle valves 1 and 2, and the needle valve opens\ Secure the valve and open the check valve 20.

As the crank pin 51 rotates, the plunger 28 continues to descend further, and while increasing the pressure in the fuel passage 8a, the fuel passes through the fuel passage 7c, the check valve 20, and the fuel passage 8c, and is accumulated in the pressure accumulation chamber 16.

When the crank pin 51 further rotates and approaches the top dead center, the plunger 28 further descends, the notch surface 28b passes through the spill port 21, and opens a flow path between the spill port and the inside of the barrel 27 through the passage 28a.

Since the spill port 21 is connected to the low pressure side through the fuel port 32, the fuel flows out from the barrel 27 and the pressure decreases.

At this time, the suction valve 24 closes, and its suction action reduces the pressure within the fuel passage 8a.

The high pressure fuel in the pressure accumulator 16 is blocked by the check valve 20 and does not flow into the fuel passage 8a.

When the pressure in the fuel passage 8a decreases, the pressure applied to the lower part of the needle valve 12 through the fuel passage 12 pushes the needle valve 12 open against the force of the spring 14, causing the mouth! Fuel is injected from 11.

As the fuel is injected, the pressure in the pressure accumulator decreases, and when the force of the spring 14 exceeds the pressure applied to the lower part of the needle valve, the valve closes and the injection ends.

As the crank pin 51 further rotates, passing the top dead center and heading toward the bottom dead center, the plunger 28 continues to rise, and when it approaches the bottom dead center, the upper end of this plunger opens with a spill port 21, thereby sucking in fuel. and prepare for the next operation.

Note that the bushes 40, 41, 44, 48 and bearing 52 (Fig. 1) in Fig. 3 or their respective opposing pins 38, 42
, 46, 47, or between the crank pin 51, it is easy to draw the dimension ratio so that when the plunger 28 sends oil at 2000 atm, the surface pressure will be approximately 300 atm. It is a structure that can ensure reliability, and it is easily possible to increase the injection pressure by increasing the dimensional ratio of the pump drive system.

Next, based on FIG. 4, the pressure accumulator fuel injection valve 4 shown in FIG.
The structure of another embodiment of the injection pump device 4Aa connected to the injection pump device 4Aa by a high-pressure pipe will be described.

The % characteristics of this device 4Aa are as follows:
It is driven by a crankshaft 60 via a connecting rod 59 rotatably attached to a pin 58 of a crosshead 57. The configuration of the injection pump device 4Aa other than this is as follows:
Like the injection pump 4A shown in FIG. 2, it is completely the same as the known Bonyu type.

A bush is fixed to the small end of the connecting rod 59 and acts as a bearing for the pin 58. The large end is rotatable on a crank pin 61 of a crankshaft 60 via a bearing, and is attached to a ring cap 62 by tightening a bolt 63. Therefore, the plunger 56 moves upward by the rotation of the crank 1160.The pump device 4Aa is connected to the fuel passage 8a of the pressure accumulation type injection valve 4B via a nut 65 via a high pressure pipe 64.

Therefore, the operation of the jH injection pump device 4Aa will be explained. Of course, the pressure accumulator type injection valve 4B operates in exactly the same manner as the one shown in FIG. The fuel injection pump 4Aa has a camshaft crank IItlI
Cross head 57 through connecting rod 59 by rotation of 60
and moves the plunger 56 up and down to supply high pressure fuel to the high pressure pipe 6.
5f: Oil is sent to the pressure accumulation type injection valve 4B through the fuel injection valve, and the same operation as the unit injector shown in FIG. 2 is performed.

According to the present invention having the above configuration, the pressure accumulation type fuel injection device has a configuration in which the injection rate is uniquely determined by the pressure in the pressure accumulation chamber and the diameter of the injection port, and is completely independent of the speed of the plunger.

Therefore, it is desirable to drive the brake plunger by a mechanism similar to a crank mechanism with a substantially sinusoidal rate of change of speed driven by an engine piston.

The granger drive system of the present invention is a positive type that does not require a spring, so there is no risk of damage due to spring stress or surging, and a large lift can be achieved. The design and fabrication of high pressure fuel injectors can be facilitated by adopting small diameter plungers that are easy to use.

Thus, the present invention is that there are no point or line contacts in the plunger drive system.

Since the plunger is driven by a crankshaft instead of a cam, high-pressure injection is possible without the use of a pressure booster.
The injection device has become easier.

[Brief explanation of the drawing]

Figure 1 is a front view, Figure 2 is an enlarged sectional view of the fuel injection device,
FIG. 3 is an enlarged sectional view of the main part, and FIG. 4 is a sectional view showing another embodiment of the injection pump device. 4... Pressure accumulation type fuel injection device, 4A... Fuel injection pump, 4B... Pressure accumulation type fuel injection valve, 4b... Fuel injection valve,
7 a, 7 b, 7 c, 8 a, 8
b + 8 c - fuel passage, 9...pressure accumulator, 11...
・Needle valve body, lla... Injection port, 12... Needle valve, 14
... Rine, 16... Pressure accumulation chamber, 20... Check valve, 2
1...-spill boat, 23... suction return valve body, 24...
・Suction-back valve, 27 Barrel, 28...Plunger, 37
Cross bed, 39... Link, 430 Tsuka-arm, 4... Connecting rod, 50 - Camshaft, 51 - Crank pin < 4 A a... Injection pump device, 56...
・Plunger, 59...Connecting rod, 60...Crankshaft,
64...High pressure pipe. Patent applicant: Kanesaka Institute of Technology Co., Ltd. Procedural amendment (voluntary) November δ, 1988 Date? 1! J Permission Office Director Kazuo Sugi 1, Indication of the case 1988 Patent Application No. 24762 2, Name of the invention Fuel injection device 3, Person making the amendment 4, Agent fil Column for the title of the invention in the specification (2) Akenoge - Anzu's %j near F g+, I request's shear i
ll and Detailed Description of the Invention, Column 6, Amendment (1) Specification No. 1, Title of Invention: ``Fuel Injection Device J for Compression Ignition Engine,'' amended to ``Fuel Injection System J.'' 2) On page 1 of the same, amend the claims as shown in the attached sheet. (3) Add ``etc.'' after ``compression ignition engine'' in line 19 of the 1st page of the same. 4′! A fuel injection pump with a suction valve in the high-pressure fuel passage communicating with the barrel in which the plunger is inserted, and the valve opening pressure is controlled by the fuel pressure and spring force. It has a fuel injection valve having a needle valve and an injection port that is opened and closed by the needle valve, a pressure accumulation chamber is provided in a part of the high pressure fuel passage, and the pressure low FK of the high pressure fuel passage is used to control the needle valve. In the fuel injection device for a compression ignition engine, the fuel injection device for a compression ignition engine is constituted by a pressure accumulator fuel injection valve that opens the valve, starts fuel injection, and opens a needle valve to end fuel injection when the pressure in the pressure accumulation chamber decreases. This purulent injection device is characterized in that the plunger is driven by a crankshaft and a connecting rod.

Claims (1)

[Claims] a high-pressure furnace communicating with a barrel in which a plunger is inserted;
A fuel injection valve having a fuel injection pump having a suction return valve in the fuel passage, and a needle valve whose valve opening pressure is opened by the pressure of the fuel and a spring force, and an injection port which is opened and closed by the side valve. A pressure accumulation chamber is provided in a part of the high-pressure fuel passage, and when the pressure in the high-pressure fuel passage is low, the needle valve is opened and fuel injection is started. In a fuel injection device for a compression ignition engine consisting of a pressure accumulating fuel injection valve that opens and completes fuel injection,
A fuel injection device for a compression ignition engine, characterized in that the plunger is driven by a crankshaft and a connecting rod.