JPS63167068A - Advancer for accumulator type fuel injection device - Google Patents

Abstract

PURPOSE:To make it possible to accurately control fuel injection time by connecting a valve closing pressure chamber partitioned by piston united with a needle valve to a suction pump through an opening/closing valve and making it possible to adjust the opening time of the opening/closing valve by a timer mechanism, according to the revolution number of an engine. CONSTITUTION:An accumulator type fuel injection device has a needle valve 3 stored freely in advancement and retreat inside an injection tube 2 and is provided with an accumulation chamber 6 on the injection port 1 side and a valve opening pressure chamber 5 on the opposite side to the injection port 1 by piston 4 formed at the valve axis of this needle valve 3, respectively. The valve opening pressure chamber 5 is connected, through a communication passage, to an injection pump chamber 9 which is pressurized by the operation of a plunger 10. In this case, the valve closing pressure chamber 5 is connected to a suction pump (both are omitted from Fig.) through an opening/closing valve which is adjustable of the starting time to open the valve by timer mechanism according to the revolution number of an engine. And the needle valve 3 is controlled to be opened by lowering the internal pressure of the valve closing pressure chamber 5 with the opening of the opening/closing valve.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an advance device for an accumulator fuel injection device, and in particular, it has a simple configuration, can accurately control the fuel injection timing, and has the following features: The present invention relates to an advance angle device for a pressure accumulation type fuel injection device that is advantageous in achieving downsizing.

Further, the pressure accumulation type fuel injection device to which the present invention is applied includes, for example, as shown in FIG. A check valve 8 for preventing backflow is interposed in the middle to form a pressure accumulation chamber between the injection valve 3 and the check valve 8, and an injection pump chamber 9 is formed upstream of the check valve 8. This fuel injection device includes an inlet valve 12 that connects and disconnects an intake passage 11 to the fuel injection device 9. This type of fuel injection device often combines an injection pump chamber into one main body B as a unit injector, but the invention is not limited to this. It is also possible to provide sections and connect them with piping.

<Prior Art> Conventionally, as an advance device for a pressure accumulation type injection device, there is one disclosed in, for example, Japanese Unexamined Patent Publication No. 49-70031.

As shown in FIG. 13, the advance angle device of this conventional pressure accumulator type injection device has an eccentric shaft 16 which is rotatably supported on the side of the engine.
The cam follower 16' is swingably supported by the engine, and the phase of the eccentric shaft 16 is changed in accordance with the engine speed to change the position where the cam follower 16' contacts the fuel cam 17, thereby adjusting the injection timing. It is possible to do so.

The injection pump P, which is assembled integrally with the nozzle N, has a bushing rod 18 and a rocker arm 1 at a cam follower 16°.
It is linked via 9.

In this conventional advance device for a pressure accumulation type injection device, the injection start timing is adjusted by changing the timing at which the plunger of the injection pump P rises to adjust the timing at which pressure reduction starts on the upstream side of the check valve.

(Problems to be Solved by the Invention) In the advance angle device of such a conventional pressure accumulation type injection device, the phase of the eccentric shaft 16 is usually changed in both forward and reverse directions in accordance with the engine rotation speed. . The locus of this eccentric shaft 16 draws a predetermined circular arc, so the amount of movement of the cam follower 16° changes sinusoidally with respect to the phase change of the eccentric shaft 2, and the injection timing changes linearly with respect to the engine rotation speed. In order to achieve this, it is necessary to provide a correction mechanism that linearly corresponds the 16° position change of the cam follower to the phase change of the eccentric shaft 16, but adding such a correction mechanism would complicate the structure and , becomes large.

Further, when the bushing rod 18 is interposed as described above, the inclination of the bushing rod 18 changes as the position of the cam follower 16' changes, and the clearance between the bushing rod 18 and the rocker arm 19 changes. For this reason, impact noise is generated, the rocker arm 19 vibrates, and wear progresses more easily, which is disadvantageous in terms of improving durability and also disadvantageous in increasing the speed of the engine. Become.

Furthermore, in order to connect the cam follower 16 to the eccentric shaft 16, the base end of the cam follower 16° is split into two parts.
Since it is necessary to connect using bolts or the like, there are also problems such as disadvantageous structure of the base end of the cam follower 16'.

The present invention has been made in consideration of the above circumstances, and is a pressure accumulating fuel injection system that has a simple configuration, can accurately control fuel injection timing, and is advantageous in terms of downsizing. The object of the present invention is to provide an advance angle device for a device.

Means for Solving the Problems> In order to achieve the above object, the advance device for a pressure accumulator fuel injection device according to the present invention includes a fuel passage formed in the main body at the terminal end of the fuel passage. In addition to providing an injection valve that opens and closes, a check valve that prevents backflow is interposed in the middle to form a pressure accumulation chamber between the injection valve and the check valve, and an injection pump chamber and this pressure accumulation chamber are provided upstream of the check valve. An advance device for a fuel injection device having an inlet valve that connects and disconnects a suction path to an injection pump chamber, wherein pressure is applied to the upstream side of the check valve to bias the injection valve in the closing direction. A suction pump is connected to the closing pressure chamber via an opening/closing valve, and a timer mechanism is provided to adjust the opening timing of the opening/closing valve in accordance with the engine speed. It is characterized by having been established.

Although it is possible to connect the closing pressure chamber and the opening/closing valve through a passage separate from the part of the fuel passage on the upstream side of the check valve, , connecting via the injection pump chamber and inlet valve makes the structure simpler;
Moreover, it is advantageous because it can be made compact.

In this case, it is necessary to provide a switching valve upstream of the inlet valve to switch and connect the fuel supply circuit and the suction pump, but since this switching valve can also be used as an on-off valve, there is no need to increase the number of parts. Therefore, it is advantageous. Even if this switching valve rotates a loaf having one switching passage,
A plurality of on-off valves may be linked.

Although it is possible to provide the above-mentioned artificial valve separately from the plunger that enters the injection pump chamber, it is advantageous to incorporate it into the plunger in terms of compactness and miniaturization.

Additionally, although this artificial valve may be configured with a check valve, it is advantageous to use a spool valve, which does not have the risk of prematurely closing the valve during high-speed operation and can accurately control the amount of fuel injection. . When the inlet valve is configured with a pool valve, the volume at one end of the spool chamber decreases due to suction for injection start control, which may cause an error in the fuel injection amount. It is advantageous to connect a constant pressure replenishment circuit which supplies fuel to the inlet valve at a predetermined pressure until retraction to dead center, so that the position of the spool at the start of fuel supply by the force pump is constant.

The timer mechanism may be configured similarly to the timer mechanism attached to the valve train, and can also be used as the timer mechanism of the valve train.

Furthermore, a check valve 39 and a pressure setting valve 40 connecting the second pressure accumulation chamber 41 and the first pressure accumulation chamber 6 are arranged around the injection pipe, and an injection pump chamber is arranged on the other side to connect the second pressure accumulation chamber 41 and the first pressure accumulation chamber 6. When disposed around the upper part of the injection pipe 2, it is possible to easily form a passage inside the main body, and it is advantageous in terms of miniaturization and compactness.

<Operation of the Invention> As described above, in the advance angle device of the pressure accumulation type fuel injection device according to the present invention, since the closing pressure chamber is connected to the suction pump via the opening/closing valve, it is not necessary to open the opening/closing valve. By lowering the internal pressure in the valve-closing pressure chamber, the differential pressure acting on the piston can be increased, and the needle valve can be opened. and,
By adjusting the opening timing of the on-off valve using a timer mechanism, the opening timing of the needle valve can be adjusted. Since this timer mechanism may be constructed in the same manner as the timer mechanism of a conventionally known valve train, it is possible to accurately and linearly change the fuel injection timing with respect to the engine speed.

<Effects of the Invention> Therefore, it is possible to develop an accumulator fuel injection device that can accurately and linearly correspond the injection timing to the engine rotational speed with a simple configuration without providing a complicated correction mechanism as in the conventional example described above. You can get a corner device. Additionally, whereas conventional advance angle devices are built into the pump drive system, the advance angle device can be configured within the fuel supply system independently from the pump drive system, increasing versatility. can. Furthermore, since a cam follower, push rod, rocker arm, etc. are not provided, it is extremely advantageous in terms of miniaturization.

<Example 1> Hereinafter, one example of the present invention will be described in detail based on the drawings.

The fuel injection device has a unit injector U, a fuel supply circuit F for supplying fuel thereto, and a constant pressure replenishment circuit C,
An advance angle control circuit T is provided between the fuel tank 20, which is shared by the fuel supply circuit F and the constant pressure replenishment circuit C, and the unit injector U.

The fuel supply circuit F, constant pressure replenishment circuit C, and advance angle control circuit T are switched and connected to the inlet valve 12 of the unit injector U by a switching valve (2).

The fuel supply circuit F includes a fuel tank 20, a fuel pump 2
1, a pressure regulator 22, a governor 23, and a forced pump 24, and is configured to supply fuel at a predetermined pressure adjusted in accordance with the engine speed to the unit injector U. The timing of this fuel supply is determined by the switching valve (2).

The unit injector U is connected to the main body B as shown in Fig. 3.
It has an injection pipe 2 that is assembled integrally with the injection pipe 2, and a plurality of injection ports 1 are opened at the lower end of the injection pipe 2. This injection pipe 2
A needle valve 3 is disposed inside the injection valve 3 so as to be movable back and forth so as to open and close the injection pipe 2 in the vicinity of the injection port 1. A piston 4 is formed on the valve shaft of this needle valve 3, and this piston 4
As a result, a valve-closing pressure chamber 5 is defined in a portion of the injection pipe 2 opposite to the injection port 1, and a small-capacity first pressure accumulation chamber 6 is defined in a portion of the injection port. A communication passage 7 is formed between the piston 4 and the inner circumferential surface of the injection pipe 2, which communicates the valve-closing pressure chamber 5 with the pressure accumulation chamber 6. A check valve 8 is inserted which is moved toward and away from the valve and whose peripheral surface slides into contact with the inner peripheral surface of the injection pipe 2 . A communication passage 2 is provided in the valve closing pressure chamber 5.
An injection pump chamber 9 is connected through the injection pump chamber 5, and a plunger IO is inserted into the injection pump chamber 9 so as to be movable forward and backward. An inlet valve 12 for opening and closing a suction passage 11 to the injection pump chamber 9 is provided within the plunger 10 .

That is, the plunger lO is supported by the main body B so as to be movable in the vertical direction, and a spool chamber 27 for storing the spool 26 is formed therein. The spool 26 has a hollow hole 28 extending from the lower end to the vicinity of the upper end, and communication passages 29 and 30 communicating with the switching valve V are formed at an intermediate height between the spool 26 and the plunger 10. Further, valve holes 31 and 32 are formed at predetermined positions from the lower end of the plunger 10 to communicate the injection pump chamber 9 with the pressure accumulation chamber 43 at the lower part of the spool chamber 27, and the peripheral wall of the spool 26 is provided with valve holes 31 and 32 at predetermined positions from the lower end of the plunger 10. A valve hole 33 corresponding to the valve hole 31, 32 passes through the height. Furthermore, a bias path 34 is formed in the circumferential wall of the spool 26, leading from the upper end of the hollow hole 28 to the circumferential surface. This bias passage 34 is a passage 3 formed in the plunger 10.
5, it communicates with a bias chamber 36 in the upper part of the spool chamber 27 and a valve-closing spring chamber 37 in the main body B.

The valve-closing spring chamber 37 is arranged above the valve-closing pressure chamber 5, and the upper end of the valve shaft of the needle valve 3 is inserted into the valve-closing spring chamber 37 so as to be able to rise and fall. Further, a valve closing spring 38 is inserted into the valve closing spring chamber 37 to bias the valve shaft downward.

The first pressure accumulation chamber 6 is connected to a large-capacity second pressure accumulation chamber 41 via a check valve 39 and a pressure setting valve 40.

This second pressure accumulating chamber 6 is formed in the main body B in an annular shape surrounding the upper part of the valve shaft of the needle valve 3. The above check valve 39
is configured such that the valve is opened when the internal pressure of the first M pressure chamber 6 reaches a high pressure of, for example, 700 to 1000 atmospheres, and fuel flows from the first pressure accumulation chamber 6 to the second pressure accumulation chamber 41, and the pressure setting The valve 40 is opened when the internal pressure of the first pressure accumulator 6 drops to a predetermined pressure higher than the valve closing pressure due to the opening of the needle valve 3, and the internal pressures of the first pressure accumulator 6 and the second pressure accumulator 41 are set to a predetermined level. When the valve closing pressure (for example, 270 atmospheres) is reached, the valve is closed by the valve closing spring 42.

In addition, both valve holes 31 and 32 formed in the plunger 10
One valve hole 31 is formed to have a much smaller diameter than the other valve hole 32, and opens above the other valve hole 32 from the bottom dead center of the spool 26.

The constant pressure replenishment circuit C is branched from the downstream side of the pressure regulator 22 of the fuel supply circuit F, and the advance angle control circuit T includes a switching valve ■ serving as an on-off valve whose opening timing is controlled by a timer mechanism 43, and a suction pump 45. It is equipped with This suction pump 45 consists of a plunger 47 inserted into a plunger chamber 46 so as to be movable back and forth, and a spring 48 that biases the plunger 47 in a direction in which the volume of the plunger chamber 46 increases. Driven.

Note that 50 is a closing spring for the check valve 8, and 51 is a closing spring for the check valve 39.

In the above configuration, at the time point in FIG. 12a when fuel starts to be supplied to the unit injector U, the spool 26 is located at the bottom dead center and the plunger lO is located at the bottom dead center as shown in FIG.
is positioned at top dead center.

At this point, the inlet valve 12 is opened, the check valve 8, the check valve 39, and the pressure setting valve 40 are closed, and the bias chamber 36 is closed.
is in communication with the hollow hole 28 of the spool 26. From this point on, when fuel starts to be supplied with the plunger 10 at the top dead center position, the spool 26 rises from the bottom dead center, and as shown in FIG.
The spool 26 stops at a position where the inner hollow hole 28 is cut off and the pressures of the bias chamber 36 and the pressure accumulation chamber 43 are balanced, and fuel supply ends. At the point in time in FIG. 12C, a cam (not shown) begins to lower the plunger lO. As a result, the volume of the injection pump chamber 9 begins to decrease. As the volume decreases, fuel flows from the injection pump chamber 9 into the pressure accumulation chamber 43 through the valve holes 31 and 32, and the spool 26 rises again. While this spool 26 is rising, the valve pressure chamber 5 is closed.
, the internal pressures of the injection pump chamber 9 and the pressure accumulation chamber 43 rise. Eventually, as shown in FIG. 5, the inlet valve 12 is closed at time d, and the internal pressure of the pressure accumulator 43 becomes constant. At this point d, the check valve 8 is opened, and the plunger 10 continues to descend, closing the pressure chamber 5, the injection pump chamber 9, and the first
The internal pressure of the pressure accumulating chamber 6 further increases, and after the point e when the pressure exceeds a predetermined pressure, the check valve 39 is opened as shown in FIG.
At a point in time when the plunger 10 reaches the bottom dead center and the internal pressures of the valve-closing pressure chamber 5, the injection pump chamber 9, the first pressure accumulation chamber 6, and the second pressure accumulation chamber 41 are balanced, a non-return check is performed as shown in FIG. Valve 8 and check valve 39 are closed. After this, at time g, the switching valve V
When the suction passage 11 is connected to the advance angle control circuit T by switching the
The internal pressure of the hollow hole 28 of the spool 26 and the pressure accumulation chamber 43 decreases, and during that time the spool 26 is moved between the bias chamber 36 and the pressure accumulation chamber 4.
3, and at time h, the small-diameter valve hole 31 is connected to the valve hole 33, as shown in FIG. As a result, the internal pressure of the valve-closing pressure chamber 5 gradually decreases from time h, while the internal pressure of the pressure accumulating chamber 43 increases under the influence of the internal pressure of the valve-closing pressure chamber 5, and the position of the spool 26 rises. During this period, the internal pressure in the valve-closing pressure chamber 5 decreases, and at a point in time when the differential pressure overcomes the internal pressure in the valve-closing spring chamber 37 and the force of the valve-closing spring 38 acting on the needle valve 3, the needle valve 3 starts to open. be done.

Even if the needle valve 3 starts to open, the internal pressure in the valve-closing pressure chamber 5 decreases slowly due to the throttling action of the small-diameter valve hole 31, so the opening amount of the needle valve 3 is also small. 1M
The decrease in the internal pressure of the pressure chamber 6 can be suppressed to a small level. Spool 26
continues to rise, and after the point in time when the large diameter valve hole 32 communicates with the valve hole 33, the valve closing pressure chamber 5, injection pump chamber 9, and pressure accumulation chamber 43 are communicated through the large valve hole 32, so the valve closes. The internal pressure of the pressure chamber 5 is further reduced, and the needle valve 3 is opened further as shown in FIG. Simultaneously with this valve opening, the pressure setting valve 40 is opened, and a large amount of fuel is ejected from the second pressure accumulation chamber 41 via the first pressure accumulation chamber 6 and the injection port 1. When the internal pressures of the first pressure accumulation chamber 6 and the second pressure accumulation chamber 41 drop to a predetermined value, the differential pressure acting on the piston 4 decreases, and the pressure acting on the valve shaft from the valve closing spring 38 and the valve closing spring chamber 37 decreases to the piston. When the pressure difference becomes greater than the differential pressure acting on the needle valve 3, the needle valve 3 is closed and the fuel injection is completed. After this, the plunger IO rises from the bottom dead center toward the top dead center after time 1. The spool 26 descends to an intermediate height by the end of fuel injection, as shown in FIG. 12(2), but further descends to the bottom dead center when the plunger 10 rises.

In this case, due to the communication between the advance angle control circuit T and the suction passage 11, the internal pressure of the pressure accumulator 43 becomes more constant than at the initial point a, and then, for example, if the same amount of fuel as last time is supplied, then the pressure accumulator 43 and the injection pump chamber 9 that communicates with it will be lower than before, and there will be a gap between the plunger IO and the cam that drives it, which may cause noise such as impact noise. The constant pressure supply circuit C is connected to the suction passage 11 by switching the switching valve V for an appropriate period before the spool 26 finishes descending to the bottom dead center.

In the above embodiment, the valve holes 31 and 32 are formed of large and small circular holes as shown in FIG.
As shown in FIG. 10 (2), it may be composed of a circular hole 32 and a narrow groove 31 continuous thereto, or, for example, as shown in FIG.
), it may be constructed of an oval-shaped hole in which the small diameter part 31 and the large diameter part 32 are continuous.

In addition, the above-mentioned switching valve V has one passage passing through one rotor so that the rotor is rotated at the same rotation speed as the engine, but such an integrated rotor-type switching valve V It is also possible to configure the switching valve V with a plurality of interlocking valves.

Furthermore, as shown in FIG. 11, the inlet valve 2 is composed of a check valve, and a valve opening spring 52 is provided in place of the bias chamber 36.
It is also possible to use a unit injector U' in which the second pressure accumulator 41 is omitted.

Furthermore, in the above-mentioned embodiment, the injection pump chamber 9 is located around the jet pipe 2, and the second M pressure chamber 41 and the first M pressure chamber 6 are located on the other side.
The check valve 39 and the pressure setting valve 40 that connect the Moreover, it can be configured compactly.

[Brief explanation of the drawing]

FIG. 1 is an equivalent circuit diagram schematically showing the main parts of the present invention, and FIG.
The figure is an equivalent circuit diagram of one embodiment of the present invention, FIGS. 3 to 9 are longitudinal sectional views showing the operating states of the unit injector in order, and FIG. 10 (1) is a front view showing the valve hole of the plunger.
Figure 10 (2) and Figure 1O (3) are front views showing the valve holes of different plungers, Figure 11 is a vertical cross-sectional view of another unit injector, and Figures 12 (1) to (6) are time Figure 12 (1) shows the change in the internal pressure of the pressure accumulator at the bottom of the spool chamber, Figure 12 (2) shows the change in the spool position, Figure 12 (3) shows the change in the plunger position, and Figure 12 ( 4) shows the change in the internal pressure of the injection pump chamber, Fig. 12 (5) shows the change in the lift amount of the needle valve, and Fig. 12 (6) shows the change in the internal pressure of the first pressure accumulator chamber and the second pressure accumulator chamber, and the change in the fuel injection rate. 13 is a configuration diagram of a conventional example. 3... Injection valve and needle valve), 5... Valve closing pressure chamber,
6... First pressure accumulation chamber, 8... Check valve, 9... Injection pump chamber, 11... Suction path, 12... Inlet valve, 14...
...Suction pump, 15...Timer mechanism, B...Main body, ■...Opening/closing valve. 4th round 5th river 6th figure￥ 7 bile] 7th chapter 2nd stage ? Amended written amendment C garoku°) November 28, 1986

Claims (1)

[Claims] 1. An injection valve 3 for opening and closing the fuel passage is provided at the terminal end of the fuel passage formed in the main body B, and a check valve 8 for preventing backflow is interposed in the middle of the injection valve 3 and check valve 8. An advance device for a fuel injection device which has a pressure accumulation chamber 6 formed between the check valve 8 and an injection pump chamber 9 upstream of the check valve 8 and an inlet valve 12 that connects and disconnects the suction path 11 to the injection pump chamber 9. There is a valve-closing pressure chamber 5 on the upstream side of the check valve 8 for applying pressure to the injection valve 3 in the valve-closing direction.
A suction pump 14 is connected to the closing pressure chamber 5 via an opening/closing valve V, and a timer mechanism 15 is provided for adjusting the opening timing of the opening/closing valve V in accordance with the engine speed. An advance device for a pressure accumulator fuel injection device, characterized by