JPS59200059A - Fuel injection pump injection rate control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to an injection rate control device for a fuel injection pump.

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

For example, diesel 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 medium to high speed rotation regions, efficient combustion can be achieved by shortening the injection period and increasing the injection rate depending on the strength of the intake swirl.

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 would be 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 was made based on the above circumstances, and provides a fuel injection pump that can obtain an optimal injection rate over the entire operating range of the engine by changing the amount of accumulated fuel according to the operating conditions of the engine. This invention attempts to provide an injection rate control device.

That is, the present invention forms a control surface that varies in height along the circumferential direction with respect to the axial direction on the accumulate piston that can release a part of the fuel pressurized by the pump plunger, and the above-mentioned accumulate piston An oil-tight chamber is provided between the cylinder and the cylinder into which the piston is slidably fitted, and the cylinder is formed with a control hole that opens into the oil-tight chamber and is opened and closed by the control surface, and the accumulation piston is provided with 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 is connected to the control vane, and the pressure of the working fluid according to the operating condition is transmitted to the control vane to rotationally displace the control vane and the accumulate piston, thereby creating a connection between the control surface and the control hole. By adjusting the relative position to be larger at low speed rotation (and smaller at higher speeds), the fuel accumulation rate is increased at lower speed rotations and smaller at higher G speeds.

The details of the present invention will be explained below based on a first embodiment applied to a distribution type fuel injection pump shown in Figs. ff11 to 4.

In the figure, 1 is a housing, into which a plunger 2 is slidably inserted. The plunger 2 is a drive shaft 3 that rotates in synchronization with a diesel engine (not shown).
are connected to each other via a coupling 4 and a face cam 5. The camp ring 4 always transmits the rotation of the shut 3 to the face cam 3 and the plunger 2, and
Face cam 5 and plunger 2 against shaft 3
movement in the axial direction.

Due to sliding contact between a face cam 5 provided on the plunger 2 and a cam roller 6 provided opposite to the face cam 5, the plunger 2 is reciprocated a number of times corresponding to the number of cylinders of the engine during one revolution. When the plunger 2 is in the suction stroke in which it is moved to the left in FIG. 1 during each reciprocating motion, the tip of the plunger 2 Fuel in the pump chamber 10 is sucked into the pump chamber 10 through one of the plurality of suction grooves 8 provided on the outer periphery of the parrot 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. The fuel is supplied to the discharge port 13 through the vertical hole 11 provided in the figure and one distribution groove 12 provided on the outer circumferential surface of the plunger 2, and through the discharge port 13 to the fuel injection valve of the corresponding cylinder of the engine (not shown). The spill ring 14, which is a member for adjusting the fuel injection amount, 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 according to the timing of opening the spill boat 15. The fuel injection amount supplied from the discharge port 13 is determined. When the spill boat 15 is opened, the fuel in the pump pressurizing chamber 7 is returned to the pump chamber 10 through the vertical hole 11 and this hole 15.

The spill ring 14 is connected by a supporting lever 16 to a governor sleeve 18 that responds to the movement of the flyweights 17, and a tension lever 19.
It is already known that the main engine is connected to an adjuster lever 21 by a spring 20, and the fuel injection amount is controlled according to the vehicle speed or the 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 3o is attached to the pump pressurizing chamber 7. In other words, the pump pressurizing chamber 7 is substantially constituted by a space surrounded by the housing 1, the plunger 2, and the accumulator 30. Accumulator 3o 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. cylinder 3
A seal plate 1, 33 is sandwiched between
is kept oil-tight. An accumulation hole 34 connected to the pump pressurizing chamber 7 is formed in the seal plate 33, and a pressure receiving piston 35 is slidably inserted into the accumulation hole 34. One end of an accumulation piston 36 is brought into contact with the pressure receiving piston 35, and the pressure receiving piston 35 and the accumulation piston 36 move together in the axial direction. The accumulation piston 36 has a control surface 37 formed on a surface located on the opposite side of the pressure receiving piston 35. This control surface 37
is formed to have a different height along the circumferential direction than the axial direction, and has, for example, an axially symmetrical helical surface.

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 this oil-tight chamber 38 . The control hole 39 is opened and closed by a control surface 37 of the accumulation piston 36.

An orifice screw 70 is screwed into the cylinder 31 on the opposite side of the oil-tight chamber 38 with respect to the control hole 39. A throttle hole 71 is formed on the control hole 39 side side of the orifice screw 70. The throttle hole 71 connects to the fuel passage 4 through a communication hole 72 provided perpendicularly to the axis of the fuel passage 4.
It communicates with 0. Therefore, the control hole 39 is communicated with the pump chamber 10 via a throttle hole 40 formed in the orifice screw 70, an annular groove 41, and a communication passage 42 formed in the housing 1.

A supply hole 46 is communicated with the oil-tight chamber 38 separately from the control hole 39 . The supply hole 46 is connected to the oil-tight chamber 3 no matter where the accumulate piston 36 is located in the axial direction.
8, and 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 . The suction check valve chamber 47 communicates with the annular groove 41 via the suction passage 50, and therefore communicates with 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 becomes lower than a predetermined value. If the value exceeds the 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.

A piston rod 54 protruding from the accumulation piston 36 slidably passes through the partition plates 51 and 52. As shown in cross section in FIG. 3, this piston rod 54 has two flat surfaces 54a and 5 facing away from each other.
4a, and a control vane 55 is connected to this portion. The control vane 55 is fitted with the flat surfaces 54a, 54a of the piston rod 54, so that it can rotate integrally with the accumulate piston 36. However, the piston rod 54 can move 47.1 degrees in the axial direction relative to the control shaft 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 5G.

The control hone 55 is configured to be able to rotate by sliding on the inner surface of the cylinder 53, but between the hone 55 and the cylinder 53, as shown in FIG. Working fluid introduction chamber 57.57 and low pressure release chamber 58.
58 is formed.

The working fluid introduction chamber 57.57 communicates with the fuel passage 40 via a pressure introduction hole 59.59 formed in one partition plate 51 and an annular groove 60. Also low pressure open chamber 58.58
communicates with the inside of the camp 62 via a relief hole 61 formed in the other partition plate 52.

The cap 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 receiver 64 rotatably mounted on the tip of the piston rod 54 is inserted between the cap 62 and the spring 62.
．． The rack is handed over. This spring 65 biases the accumulation piston 36 toward the pump pressurizing chamber 7 . A through hole 66 is formed in the cap 62,
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 inside of the low-pressure open chamber 58 is maintained at approximately atmospheric pressure for five days. Note that 67.67 does not show an O-ring.

The operation of the first embodiment based on such a 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 pressure receiving piston 35 receives fuel pressure on its left end surface, and therefore, together with the accumulating piston 36, resists the pressing force of the spring 65. and move it to the right. Since the fuel in the oil-tight chamber 38 is pressurized by the control surface 37 of the accumulating piston 36, an amount corresponding to the amount of movement of the accumulating piston 36 is released from the control hole 39 into the pump chamber 10.

When the Mil 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 fuel in the pump pressurizing chamber 7 is transferred to the accumulation piston 36.
Since the amount of fuel that has moved is allowed to escape to the accumulation hole 34, the amount of fuel that is sent from the discharge port 13 to the combustion chamber of the engine through a fuel injection nozzle (not shown) is reduced by the amount that has escaped.

On the other hand, when the pressure feeding of the fuel ends and the plunger 2 reaches the suction stroke, the fuel pressure in the pump pressurizing chamber 7 decreases, so the pressure receiving piston 35 and the accumulating piston 36 move to the left under the pressing force of the spring 65. Moved back. During this process, the fuel pressure in the oil-tight chamber 38 decreases, so the check valve 49 in the suction check valve chamber 47 opens the suction passage 50.
The fuel in the pump chamber 10 is introduced into the oil-tight chamber 3B. When the nacumulate piston 36 moves further to the left, the control valve 37 opens the control hole 39.
The fuel in the pump chamber 10 is guided into the oil-tight chamber 38 through the oil-tight chamber 38.

When the fuel pressure in the oil-tight chamber 38 becomes nearly equal to the fuel pressure in the pump chamber 10, the check 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.
and the relative distance along the axial direction of the control hole 39.

Since 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 ζ control vane 55.
This is possible by introducing fluid pressure into the working fluid introduction chamber'b7.57. 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 in the pump chamber 10 increases depending on the pump rotation speed and the engine rotation speed.

To be more specific, in a low-speed operating range such as when the engine is idling, the fuel pressure in the pump chamber 10 is low, so the fuel passage 40, annular groove 60, and pressure introduction hole 59.59 The pressure of the fuel introduced into the working fluid introduction chamber 57.57 via the working fluid introduction chamber 57.57 is also low. Therefore, the control vane 55 is biased to rotate in the counterclockwise direction in FIG.
It is stopped at a position where the pressure of 7.57 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, in order to compensate for the decrease in the injection amount, the position of the adjuster spoiler 21 during idling is adjusted and the position of the spill ring 14 is set so as to lengthen the injection time during idling. As a result, the injection time can be increased without reducing the injection amount during idling, and combustion noise during idling can be reduced.

Such injection rate characteristics are shown by the broken line in FIG. 4.

As the engine speed increases, the fuel pressure in the pump chamber 10 increases and the pressure of the fuel introduced into the working fluid introduction chambers 57 and 57 also increases in the high-speed rotation operating range, so the control vane 55 It is in the position rotated clockwise in FIG. 3 against the biasing force of the recoil spring 56. Since the rotation of the control vane 55 causes the accumulation piston 36 to rotate integrally, the spiral control surface 37 is displaced and the distance from 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 accumulation piston 36 closes the control hole 39 at a relatively early stage of the pumping stroke of the plunger 2.
The movement of 6 is stopped, and the injector decreases by 4.
9Mari injection M It becomes possible to perform efficient combustion.

When starting the engine, the relative distance between the control surface 37 and the control hole 39 is configured to be the minimum, and if the control hole 39 is set to be closed from the start of the pumping stroke of the plunger 2, the accumulation If the amount of movement of the rate piston 36 becomes substantially zero and the fuel injection amount does not decrease and the injection time is set to be equal to the time during idling, it becomes possible to increase the amount of fuel at the time of starting, Allows for smooth startup.

Further, by making the opening diameter of the pressure introduction hole 59.59 small, pressure fluctuations in the fuel passage 40 can be prevented from affecting the inside of the working fluid introduction chamber 57.57 due to the throttling effect.

When the accumulation piston 36 rotates, the spring 65
If a biasing force is applied, smooth rotation will be inhibited, but the accumulation screw I/N 36 rotates only when it is positioned to the leftmost position in the figure, and in this state, the spring receiver 64 is attached to the other side. By coming into contact with the partition plate 52, the spring 65
The biasing force of is not applied to the accumulation piston 36.

Also, depending on the injection system used, the plunger 2 may
Accumulate piston hole 34
When the accumulation rate that is released from the oil increases as shown by the broken line in the upper part of FIG. 6, the actual oil delivery rate that temporarily passes through the discharge port 13 becomes zero. It is expected that the actual oil delivery rate passing through the orifice screw 39 will increase, causing two-stage injection or injection delay as shown by the broken line in the lower diagram of Figure 6.
By regulating the flow rate of fuel flowing out from the control hole 39 by the throttle hole 71 provided in The accumulation rate of fuel escaping to 34 can be maintained at an appropriate level. Note that the dashed-dotted line in the lower diagram of FIG. 6 shows a conventional waveform in which the accumulation amount is zero.

The feature of the present invention is that when the injection period of a general injection pump is expressed in terms of crank rotation angle, the same 1! In order to provide an injection amount of +1, the injection period becomes longer at high speed rotation.For example, a pump with a high oil delivery rate that is matched to the high speed rotation range will have the shuttle characteristics shown in Figure 7a, and the injection period that is matched to the low speed rotation range will be A pump with a low oil ratio will have a condition as shown in Figure 7C, and as shown in Figure 7C, the low speed of the pump is matched to the high speed range, whereas conventional pumps could not match both the high speed range and the low speed range. By extending the injection period in the range, good injection characteristics can be obtained in the entire operating range. In order to achieve the characteristics shown in Fig. 7b, the relationship between the relative distance between the control surface and the control hole and the engine speed must be determined by drawing a straight line from the high-speed matching point starting from idle rotation, as shown in Fig. 8. It may be a characteristic that connects the two.

In this example, the rotation angle of the accumulator (piston) is
Since the pressure in the pump chamber is proportional to the rotation speed of the pump as shown in FIG. 9a, the cut of the control surface 37 is The chipped shape is
It has a spiral shape such that the notch depth in the left-right direction in FIG. 5 is proportional to the rotation angle.

Furthermore, in this embodiment, as shown in Fig. 8, the accumulated amount is maximized at idle, and the accumulated amount is decreased below idle speed, so when the engine speed is below idle speed, the accumulated amount is maximized. This is an engine stall prevention mechanism that reduces the rate amount and increases the injection amount to prevent the engine from stopping.

In the above embodiment, a distribution type fuel injection pump has been described, but the present invention can also be applied to a sub-type injection pump. If so, the check valve 49 does not need to be used.

Furthermore, as already mentioned, the fluid for operating the control vanes 55 is not limited to fuel, but may be fluid controlled according to engine operating conditions such as engine oil pressure. Good too.

If the pump chamber pressure characteristics are as shown in b and c in Fig. 9, the shape of the notch in the control surface 37 should be
By doing as follows, it is possible to obtain the characteristics as shown in FIG.

In addition, the accumulation piston 36 and the pressure receiving piston 35
It is also possible to implement it by forming it integrally.

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 the ζ fuel to escape.

As described above, according to the present invention, the control vanes are rotated by the pressure of the working fluid according to the operating conditions of the engine, and the relative distance between the control surface and the control hole is rotated at high speed. Since the accumulator piston is adjusted to become smaller as the speed increases, the amount of fuel pressurized in the pump pressurizing chamber decreases as the engine speeds up. The injection rate is controlled according to the engine operating condition G, and an appropriate injection rate required by the engine can be obtained.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a sectional view of a distribution type fuel injection pump, FIG.
The figure is m-mm in Fig. 2. 4 and 6 to 10 (characteristic diagrams); FIG. 5 is a side view showing a modification of the accumulating piston. 1. Housing; 2. ... Plunger, 7... Pump pressurization chamber, 10... Pump chamber, 30... Accumulate. 31... Cylinder, 36... Accumulate piston. 37... Control surface, 38... ...Oil seal chamber, 39...Control hole, 5...Control vane, 56...Torsion coil spring. 57, 57...Working fluid introduction chamber, 65...Spring. Patent attorney Okabe Ryu Figure 4 Time - Figure 5 Figure 6 → Krasif inner hemp
)Figure 7Figure 8Figure 9Figure 10

Claims (3)

[Claims] (1) In a fuel injection pump that pumps fuel in a pump pressurizing chamber formed by a housing and a plunger inserted into the housing, the fuel is pressurized in the pump pressurizing chamber or this pump pressurizing chamber by reciprocating motion of the plunger. A cylinder is connected to a pressure passage through which the pressurized fuel is fed under pressure, and an accumulation piston that is compressed and moved in one direction by the pressure of the pressurized fuel is fitted into the cylinder, and the accumulation piston is pressed and biased 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. An oil-tight chamber filled with hydraulic oil is formed between the cylinder and 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 accumulate piston, and the control surface A control vane that rotates integrally with the control vane is connected to the control vane, and the control surface is rotated by the control vane, and this rotation changes the relative position of the control surface and the control hole at high speeds of the engine. An injection rate control device for a fuel injection pump, characterized in that the amount of movement of the accumulation piston in one direction becomes smaller as the engine rotates at higher speeds. (2) The control hole is communicated with the pump chamber of the fuel injection pump, and the working fluid introduction chamber is also communicated with the pump chamber, so that the working fluid acting on the control vane is the fuel in the pump chamber. Characteristic claim 1
An injection rate control device for a fuel injection pump according to paragraph 1. (3) The injection rate control device for a fuel injection pump according to claim 1, wherein the control hole has a throttle that regulates the speed of movement of the accumulate piston in one direction.