JPS59155570A - Fuel injection device - Google Patents

Abstract

PURPOSE:To control so as to obtain the optimum injection rate in all operation areas including the starting time of an engine by changing fuel accumulating amount in accordance with the operating condition of the engine. CONSTITUTION:Upon low speed operation such as the idling of the engine, a fuel pressure in a pump chamber 10 is low, therefore, pressure of introduced fuel in operating fluid introducing chambers 57, 57 are low. Accordingly, a control vane 55 is energized so as to be pivoted into counterclockwise direction and is stopped at a position whereat the pressure of the introducing chamber 57 and the force of a spring 65 are balancing, therefore, the amount of injection may be decreased remarkably in case the axial distance between a control surface 37 and a control hole 39 is set so as to be large under this condition. In this case, injection time is elongated to supplement the decreased amount, then, noise upon idling may be reduced and efficient combustion may be obtained. Upon middle and high speed operations, the fuel pressure in the pump chamber 10 is increased, the vane 55 is pivoted into clockwise direction and an accumulate piston 36 is pivoted integrally, therefore, the amount of movement is restricted and the decreasing amount of the amount of injection may be reduced. Accordingly, the injection rate is increased suddenly and the efficient combustion may be obtained in all operation areas 1.

Description

[Detailed description of the invention] The present invention relates to a fuel injection device.

In general, the performance of internal combustion engines varies greatly depending on the method of fuel injection, and in the case of a direct injection diesel engine, the injection rate at which the fuel is injected from the fuel injection pump through the injection nozzle directly affects combustion.

For example, engines have the problem of large combustion noise during idling, and it is known that increasing the fuel injection time during idling is effective in solving this problem. Furthermore, in a medium to high speed rotation region, efficient combustion can be achieved by reducing the injection rate up to the time of ignition and rapidly increasing the injection rate at the time of ignition.

In this way, the required characteristics of the injection rate change depending on the operating conditions of the engine, but in the past, once the injection rate was set under a certain operating condition, this injection rate characteristic was applied as is to other operating conditions. However, there was a problem in that the injection rate could not be changed in response to changes in operating conditions.

The present invention has been made based on the above circumstances, and provides a fuel injection system in which an optimal injection rate can be obtained over the entire operating range of the engine, including when starting the engine, by changing the fuel accumulation amount according to the operating conditions of the engine. The present invention aims to provide a fuel injection device that can control the injection rate of a pump.

That is, the present invention forms a control surface with a height that is different along the circumferential direction relative to the axial direction on the accumulate piston that can release a part of the fuel pressurized by the pump plunge. an oil-tight chamber is provided between the surface and a cylinder into which the accumulation piston is slidably fitted, and the cylinder defines a control hole that opens into the oil-tight chamber and is opened and closed by the control surface; A control vane that rotates integrally with the accumulate piston is connected to the control vane, and pressure of a working fluid according to the operating condition is transmitted to the control vane to rotationally displace the control vane and the accumulate piston. By adjusting the relative position between the control surface and the control hole, the fuel accumulator l-amount can be changed.

The details of the present invention will be explained below based on examples.

1 to 6 relate to a first embodiment of the present invention, FIG. 1 is a partial cross-sectional view showing the structure of the main part of the first embodiment of the fuel injection device of the present invention, and FIG. FIG. 3 is a cross-sectional view showing the structure of the accumulator 30 and its surroundings in FIG. 1, FIG. 3 is a cross-sectional view taken along line A-1°A in FIG. 2, and FIG. FIG. 5 is a detailed diagram of the accumulation piston 36, and FIG. 6 is a characteristic diagram showing changes in fuel injection rate over time.

In FIGS. 1 to 3, reference numeral 1 denotes a housing, into which a plunger 2 is slidably inserted.

The silansha 2 is connected via a camino ring 4 and a face cam 5 to a drive shaft 3 that rotates in synchronization with a diesel engine (not shown). The coupling 4 constantly transmits the rotation of the shaft 3 to the face cam 5 and the plunger 2, and allows the face cam 5 and the plunger 2 to move in the axial direction with respect to the shaft 3.

Due to the sliding contact between the face cam 5 provided on the plunger 2 and the cam roller 6 provided opposite to the face cam 5, the plunger 2 reciprocates a number of times corresponding to the number of cylinders of the engine during one revolution. When the pump is in the suction stroke in which it is moved to the left in FIG. Fuel in the pump chamber 10 is sucked in through one of the pump chambers 8 and a suction hole 9 extending into the housing 1 .

As the plunger 2 rotates, the communication between the suction groove 8 and the suction hole 9 is broken, and at the same time, the compression stroke in which the plunger 2 moves to the right in the figure begins, and the fuel in the pump pressurizing chamber 7 is transferred to the inside of the plunger 2. vertical hole 11 and plunger 2
The fuel is supplied to a discharge port 13 through one distribution groove 12 provided on the outer circumferential surface of the engine, and reaches a fuel injection valve of a corresponding cylinder of the engine (not shown) through the discharge port 13. The spill ring 14, which is a fuel injection amount adjusting member, is movable on the plunger 2, and opens a spill boat 15 communicating with the vertical hole 11 during the compression stroke of the plunger 2, and adjusts the spill boat 15 depending on the timing. The discharge port 13
Determine the amount of fuel injection supplied from. When this spill boat 15 is opened, the fuel in the pump pressurizing chamber 7 is discharged from the vertical hole 11.
It is then returned to the waste chamber 1o through this hole 15.

The spill ring 14 is connected to a governor sleeper 18 that responds to the movement of the flyweight 17 by a sabot hinderper 16, and a tension lever 19.
It is connected to an adjuster lever 21 by a main spring 20, and the fuel injection amount is controlled according to the vehicle speed or the amount of depression of the accelerator pedal.

The pump chamber 10 is filled with fuel pressurized by a feed pump 25 provided on the drive shaft 3, and the fuel pressure is controlled in relation to the engine speed by a pressure control valve (not shown) as is known. Therefore, the fuel pressure in the pump chamber 10 increases as the rotation increases.

An accumulator 30 is attached to the pump pressurizing chamber 7. That is, the pump pressurizing chamber 7 is substantially constituted by a space surrounded by the housing 1, the plunger 2, and the accumulator 30. Accumulator 30 is shown in FIGS. 2 and 3. That is, 31 is an accumulator cylinder, which is screwed into the housing 1 via a threaded portion 32. A seal plate 33 is sandwiched between the cylinder 31 and the housing 1, and by tightening the cylinder 31 to the housing 1 with the threaded portion 32, the seal plate 33 is held between the cylinder 31 and the housing 1.
3 maintains oil tightness. An accumulation hole 34 connected to the pump pressurizing chamber 7 is formed in the seal plate 33, and an accumulation piston 36 is slidably inserted into this accumulation hole 11L34.

The accumulation piston 36 is movable in the axial direction, and the pump pressurizing chamber 7 of the accumulation piston 36 is movable in the axial direction.
A control surface 37 is formed on the surface located on the opposite side. This control surface 37 is formed to have a different height along the circumferential direction with respect to the axial direction, and as the pump rotation speed increases, the accumulated amount changes from the time of engine startup to the time of idling, as shown in FIG. For example, the shape of the surface increases as shown in FIG. 5, and then decreases as shown in FIG. 5, which becomes a triangular notch as shown by the solid line in FIG. 10 when developed. The accumulation piston 36 is connected to the cylinder 31 at two outer peripheral surfaces 36a and 36b shown in FIG.
An oil-tight chamber 38 is formed in a space surrounded by the control surface 37 and the cylinder 31. A control hole 39 provided in the cylinder 31 is opened in the oil-tight chamber 38 . The control hole 39 is opened and closed by a control surface 37 of the accumulation piston 3G. The control hole 39 is communicated with the pump chamber 10 via a fuel passage 40 formed in the cylinder 31, an annular groove 41, and a communication passage 42 formed in the housing 1.

The oil-tight chamber 38 has a supply hole 4 separate from the control hole 39.
6 are connected. The supply hole 46 is connected to the oil-tight chamber 38 no matter where the accumulate piston 36 is located in the axial direction.
This supply hole 46 communicates with a suction check valve chamber 47 formed within the cylinder 31. A check valve 49 biased by a spring 48 is accommodated in the suction check valve chamber 47 . and suction check valve 47
communicates with the annular groove 41 via the suction passage 50,
Therefore, it is electrically connected to the pump chamber 10.

The check valve 49 opens the suction passage 50 to introduce fuel from the pump chamber 10 toward the oil-tight chamber 38 when the fuel pressure in the oil-tight chamber 38 falls below a predetermined value. If it is above a predetermined value, the suction passage 50 is closed to prevent backflow.

Inside the cylinder 31, partition plates 51.
52, and a ring 53 for forming a vane chamber is sandwiched between these partition plates 51 and 52.

As shown in cross section in FIG. 3, the piston rod 54 protruding from the accumulation piston 36 has two parallel flat surfaces 54a' and 54a facing away from each other.
A control vane 55 is connected to this portion. The control vanes 55 are connected to the flat surfaces 54a, 54a of the piston rod 54.
By being fitted with the accumulating piston 3
It is designed to be able to rotate integrally with 6. However, the piston rod 54 is capable of sliding in the axial direction relative to the control vane 55. A torsion coil spring 56 is interposed between the control vane 55 and the other partition plate 52, and the control vane 55 is urged to rotate counterclockwise in FIG. 3 by the torsion coil spring 56.

The control vane 55 slides on the inner circumferential surface of the ring 53 and can rotate, but the vane 55 and the ring 53
As shown in FIG.
It is formed. The working fluid introduction chamber 57.57 passes through the fuel passage 40 via a pressure introduction hole 59.59 formed in one partition plate 51 and an annular groove 60. Further, the low pressure release chambers 58 and 58 communicate with the inside of the cap 62 through a relief hole 61 formed in the other partition plate 52.

The camp 62 is screwed onto the open end of the cylinder 31 via a threaded portion 63, and this cap 62 is attached to the partition plate 5.
1.52 and ring 53 are held down. The end of the piston rod 54 is introduced into the cap 62, and a spring 65 is inserted between the cap 62 and a spring receiver 64 rotatably mounted on the tip of the piston rod 54.
The rack is handed over. This spring 65 urges the accumulation piston 36 toward the pump pressurizing chamber 7 . A through hole 66 is formed in the cap 62, and this through hole 66 is communicated with a low pressure fuel chamber such as a fuel tank via a hose (not shown) or the like.

Therefore, the pressure in the low-pressure open chamber described above is maintained at approximately atmospheric pressure within 58.5 days. Note that 67.67 indicates an O-ring.

The operation of the first embodiment based on the above configuration will be explained.

When the plunger 2 is moved to the right in the figure and begins to pressurize the fuel in the pump pressurizing chamber 7, the accumulation piston 36
receives fuel pressure on its left end surface, so it is moved to the right against the pressing force of the spring 65. Since the fuel in the oil-tight chamber 38 is pressurized by the control surface 37 of the accumulation piston 36, an amount corresponding to the amount of movement of the accumulation piston 36 is released from the control hole 39 into the pump chamber 10. When the control surface 37 reaches the position where it closes the control hole 39, there is no place for the fuel in the oil-tight chamber 38 to escape, so the movement of the accumulation piston 36 stops.

Therefore, the amount of fuel in the pump pressurizing chamber 7 is increased by the amount that the accumulated histone 36 has moved.
Therefore, the amount of fuel sent from the discharge port 13 to the combustion chamber of the engine through a fuel injection nozzle (not shown) is limited by the amount that escaped.

On the other hand, when the spill boat shown at 15 in FIG.
It is moved back to the left in response to the pressing force of 5. During this process, the fuel pressure in the oil-tight chamber 38 decreases, so the suction check valve 47
The internal valve 49 opens the suction passage 50, and the pump chamber l
The fuel in the tank is introduced into the oil-tight chamber 38. When the accumulation piston 36 moves further to the left, the control surface 3
7 opens the control hole 39, so that the fuel in the pump chamber 10 is guided into the oil-tight chamber 38 through this control hole 39. Oil-tight room 38
When the fuel pressure within the pump chamber 10 becomes nearly equal to the fuel pressure in the pump chamber 10, the change valve 49 closes the suction passage 50.

As can be seen from the above-described operation, the amount of movement of the accumulation piston 36 determines the amount of fuel to be injected. The moving distance of this accumulation piston 36 is determined by the control surface 37.
It is influenced by the relative distance along the axial direction between and the control hole 39. Since a portion of the control surface 37 is spirally formed in this embodiment, the distance between the control surface 37 and the control hole 39 can be changed by rotating the accumulation piston 36.

The rotation of the accumulation piston 36 is controlled by the control vane 55.
This is possible by introducing fluid pressure into the working fluid introduction chamber 57.57. As the working fluid, engine oil pressure or any other pressure that is controlled according to the operating conditions of the engine can be used, but in this embodiment, the fuel pressure in the pump chamber 10 is used. The fuel pressure within the pump chamber 10 increases in accordance with the pump rotation speed, that is, the engine rotation speed. To be more specific, in a low engine speed range such as when the engine is idling, the fuel pressure in the pump chamber 10 is low, and the fuel passage 4
0, the pressure of the fuel introduced into the working fluid introduction chamber 57.57 through the annular groove 60 pressure introduction hole 59.59 is also low.

Therefore, the control vane 55 is connected to the torsion coil spring 6.
It is urged to rotate counterclockwise in FIG. 3 by the urging force of 5, and is stopped at a position where the pressure of the introduction chamber 57, 57 and the force of the torsion coil spring 65 are balanced. If the axial distance between the control surface 37 and the control hole 39 is set large in this state, the amount of fuel injected from the injection nozzle can be greatly reduced. In this case, the position of the spring 14 is set so as to lengthen the injection time during idling by adjusting the position of the adjusting lever 21 during idling to compensate for the decrease in the injection amount. This makes it possible to lengthen the injection time without reducing the amount of injection during idling, and reduce combustion noise during idling. Since excessive penetration can be suppressed and an appropriate injection rate and injection period can be provided, efficient combustion can be achieved.

Such injection rate characteristics are shown by the broken line A in FIG.

When the engine speed is increased and the engine speed is increased, the fuel pressure in the pump chamber 10 becomes high and the pressure of the fuel introduced into the working fluid introduction chambers 57 and 57 also becomes high. It is in the position rotated clockwise in FIG. 3 against the biasing force of the torsion coil spring 56. Since the rotation of the control vane 55 causes the accumulation piston 3G to rotate integrally, the spiral control surface 37 is displaced, and as a result, the distance between the control surface 37 and the control hole 39 is shortened.

Therefore, the amount of movement of the accumulation piston 36 can be kept small. As a result, the control surface 37 of the accumulating piston 36 closes the control hole 39 at a relatively early stage of the pumping stroke of the plunger 2, so the movement of the accumulating piston 36 is stopped and the amount of decrease in the injection amount is reduced. In other words, the injection rate increases rapidly and becomes as shown in characteristic B in Figure 6, resulting in efficient combustion in all operating ranges without sacrificing the performance of the injector, which is matched to high and medium speed ranges. can be done.

The most important feature of the present invention is the fuel increase characteristic at the time of engine startup. When starting the engine, pump chamber 1
Since the fuel pressure within 0 is close to atmospheric pressure, the control vane 55 twists and the biasing force of the coil spring 56 causes the third
The plunger in the figure is also in a position where it has been rotated counterclockwise.At this time, the control surface 37 is set so that it completely blocks the control hole 39 as in the state shown in FIG. If the control hole 39 is closed from the start of the pressure feeding stroke in step 2, the amount of movement of the accumulation piston 36 will become substantially zero, the fuel injection amount will not decrease, and the injection time will be reduced to idling operation. By setting the time equal to the time of , it is possible to increase the amount of fuel at the time of starting, and a smooth start can be achieved.

Furthermore, if the control hole 39 is set so that it is near X when starting and near Y when idling, as shown in FIG. 5, the accumulator 1 characteristic as shown in FIG. If f becomes lower than 1 idle rotation, the accumulated f
The fuel injection amount is reduced and the injection amount is automatically increased, so the engine is designed to maintain idle rotation even at low temperatures and prevent the engine from stopping.

Note that by making the opening diameter of the pressure introduction hole 59.59 small, pressure fluctuations in the fuel passage 4o can be prevented from affecting the inside of the working fluid introduction chamber 57.57 due to the throttling effect.

Furthermore, if the biasing force of the spring 65 is applied when the accumulating piston 36 rotates, smooth rotation will be inhibited, but the accumulating piston 36 rotates only when it is moved to the left in the figure. In this state, the spring receiver 64 comes into contact with the other partition plate 52, so that the bias of the spring 65 is not applied to the accumulation piston 36.

Next, a second embodiment of the present invention will be described.

FIG. 7 is a side view of the accumulator 30 of the second embodiment, in which only the accumulator 30 is changed from the first embodiment, showing a partial cross-section of the main part of the accumulator 30, and FIG. 8 explains its operation. FIG.

In the first embodiment, the control surface 37 blocks the control hole 39 to increase the amount at startup, but in the second embodiment, the amount is increased at startup by cutting off communication between the control hole 39 and the fuel passage 40. .

Pump chamber 1 where fuel pressure is increased according to pump rotation speed
In the fuel passage 40 which receives a pressure within zero, a winter-sleeve 81 is provided which is moved by the balance between this fuel pressure and the pressing force of the spring 80.

A triangular throttle hole 82 is formed in the sleeve 81, and this triangular throttle hole 82 faces an annular groove 83 formed in the cylinder 3. The annular groove 83 is the control hole 3
It is connected to 9. When the sleeve 81 is moved in response to the fuel pressure in the pump chamber 10, the throttle hole 82 and the annular groove 83 become electrically connected as shown by the broken line in FIG. When the pressure is extremely low, the throttle hole 82 is completely blocked and the communication between the control hole 39 and the fuel passage 40 is interrupted, as shown by the solid line in FIG. Furthermore, if the sleeve is set so that it is set as shown by the broken line in Fig. 8 during idle rotation, and the sleeve is configured so that it cannot move to the right any further, the communication area between the throttle hole 82 and the annular groove 83 will be at its maximum at idle rotation or higher. At idle rotation or lower, the sleeve 81 moves to the left and the communication area between the throttle hole 82 and the annular groove 83 is narrowed, so the outflow speed of the fuel flowing from the oil-tight chamber 38 to the fuel passage 40 decreases, causing the accumulation piston 36 to Movement speed to the right decreases. The movement speed of the accumulation piston 36 is reduced and the control surface 3 is
7 cannot reach the position where it closes the control hole 39 (if this happens, the accumulated amount will decrease and the injection amount will increase. Therefore, even at low temperatures, idling rotation can be maintained and engine stoppage can be prevented.

Although the throttle hole 82 is triangular in the second embodiment, it may be round or square depending on the pressure characteristics of the pump chamber 10. Further, although the sleeve 81 is used to open and close the flow path, a solenoid valve or the like may be used to open and close the flow path.

Further, in the first and second embodiments described above, a distribution type fuel injection pump has been described, but the present invention can also be implemented in a sub type injection pump.

Furthermore, if the fuel pressure in the pump chamber 10 is high enough to extinguish bubbles generated by cavitation, the check valve 49 may not be used.

Furthermore, as already mentioned, the fluid for operating the control vanes 55 is not limited to fuel;
It is also possible to use a fluid that is controlled according to the operating conditions of the engine, such as the pressure of engine oil.

In the first embodiment, the control surface 37 had a shape as shown in FIG. 5, and when developed, it had a shape as shown by the solid line in FIG. 10. It does not increase linearly with the engine speed as shown, but b
Even if it has a characteristic that increases in a curvilinear manner as shown in Figure 9, if it is expressed as an increasing function, the developed view of the control surface will look like the one shown by the dashed-dotted line in Figure 10, compared to Figure 9. If the control surface 37 is formed as shown in FIG. Control pressures with various characteristics can be used.

Further, the cylinder 31 may be installed in the middle of a passage connecting the injection nozzle and the pump pressurizing chamber 7 to allow fuel to escape.

As explained in detail above, according to the present invention, the control vane is rotated by the pressure of the working fluid that changes depending on the operating state of the engine to change the amount of movement of the accumulate piston. By adopting a configuration in which the accumulated amount is reduced from the time to the idle speed, it is possible to improve the startability of the engine by increasing the accumulated amount at the time of starting, and also to prevent the engine from stopping at low temperatures. be.

[Brief explanation of drawings]

1 to 6 relate to a first embodiment of the present invention, FIG. 1 is a partial cross-sectional view showing the structure of the main part of the first embodiment of the fuel injection device of the present invention, and FIG. FIG. 3 is a cross-sectional view showing the structure of the accumulator 30 and its surroundings in FIG. 1, FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2, and FIG. 4 is a change in the amount of accumulation as the pump rotation speed increases. Figure 5 is a characteristic diagram that does not show the state of the accumulating piston 3.
6 is a characteristic diagram showing temporal changes in fuel injection rate. FIGS. 7 and 8 relate to the second embodiment,
FIG. 7 is a side view of the accumulator used in the second embodiment;
FIG. 8 is an explanatory diagram of the operation. FIGS. 9 and 10 are explanatory diagrams regarding a modified example, in which FIG. 9 is a control pressure characteristic diagram, and FIG. 10 is a developed diagram showing the shape of the control surface. DESCRIPTION OF SYMBOLS 1... Housing, 2... Plunger, 7... Pump pressurization chamber, 10... Pump chamber, 31... Cylinder, 36... Accumulate piston, 37... Control surface, 38 ...Oil-tight chamber, 39...Control hole, 55...
Vane, 57... Working fluid introduction chamber. Representative Patent Attorney Takashi Okabe Figure 6 Figure 7 Part 1 Engine Recycling Information

Claims (2)

[Claims] (1) In a fuel injection pump that pumps fuel within a pump pressurizing chamber formed by a housing and a plunger inserted into the housing by reciprocating motion of the plunger, the pump pressurizing chamber or this pump pressurizing chamber pressurizes the fuel. A cylinder is communicated with a pressure passage through which the pressurized fuel is pumped, and an accumulation piston that is pushed and moved in one direction by the pressure of the pressurized fuel is inserted into the cylinder, and the accumulation piston is pushed and urged in the other direction. The accumulating piston is provided with a control surface having different heights along the circumferential direction with respect to the axial direction on a surface opposite to the pressure receiving surface that receives the pressure of the pressurized fuel, and the control surface and An oil-tight chamber filled with fuel is formed between the cylinder and the cylinder is provided with a control hole that opens into the oil-tight chamber and is opened and closed by a control surface of the accumulating piston, and the cylinder rotates the accumulating piston. By adjusting the relative position between the control surface and the control hole, the amount of movement of the accumulate piston in one direction is changed, and when the engine is idling, the distance between the relative positions is increased, and when the engine is rotating at idle, the distance between the relative positions is increased, and when the engine is rotating at idle, An injection rate control device for a fuel injection pump, characterized in that the distance between the relative positions is changed by a small amount. (2) The control hole communicates with the pump chamber of the fuel injection pump, and the working fluid introduction chamber also communicates with the pump chamber, and the working fluid acting on the vane is the fuel in the pump chamber. An injection rate control device for a fuel injection pump according to claim 1.