JPH0443825A - Injection quantity control device for fuel injection pump - Google Patents

Abstract

PURPOSE:To prevent variation of idling rotating speed by providing an opening/ closing valve to open in a prescribed rotating speed territory on a bypass flow passage to communicate a pressure chamber to a fuel chamber without resistance. CONSTITUTION:When the engine rotating speed is in an idling rotating speed territory of low speed, pressure of a fuel chamber S is low, a spool valve 2 is held on an advancing position with a coil spring 22, and the communicating port 21 formed on the outer circumference of the small diameter middle part is conformed to a bypass flow passage 31 to open it. In such idling rotating speed territory, when a tension lever 63 to operate control while finely vibrating is contacted with a piston 1, because a pressure chamber la is communicated to the fuel chamber S through a bypass flow passage 31, the piston 1 is retreated in a recessed part 32 without resistance according to vibration of the lever 63, and the vibration is not obstructed. Thus, variation of the injection characteristic is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection amount adjusting device for a fuel injection pump.
In particular, it relates to structural improvements to the dashpot section.

[Prior Art] Fig. 3 shows the main parts of a fuel injection pump for a diesel engine, in which a plunger 61 that reciprocates within a fuel chamber S and discharges fuel is fitted with a spill ring 62 on its outer periphery.
By relatively moving the spill ring 62 along the plunger 61, the amount of fuel injected is adjusted. In the figure, when moving to the left, the fuel injection amount decreases, and when moving to the right, it increases.

The spill ring 62 is moved by a control lever 68 whose tip fits into a recess on its outer periphery. It is connected to the throttle lever 65 and rotates around a support shaft 631. When the throttle lever 65 is rotated from the illustrated idle position (a in the figure) to the full throttle position (b in the figure) in the direction of the arrow,
The tension lever 63 rotates counterclockwise, and accordingly the spill ring 62 moves to the right, increasing the amount of fuel injected.

When the engine speed increases, the flyweight 66, which rotates in conjunction with the engine, gradually lowers, pushes out the governor sleeve 67, and inserts its tip into the control lever 68.
and force it to rotate clockwise. The spill ring 62 is then moved back to the left again, and the engine is adjusted to a predetermined rotation speed.

By the way, when the throttle lever 65 is rapidly returned to the idle position when the vehicle is decelerating, the tension lever 63 is accordingly rotated largely back clockwise, the spill ring 62 rapidly moves to the left end, and fuel injection is stopped. may cause surging.

Therefore, it has been proposed to provide a dashpot that abuts the tension lever 63 during its return rotation to suppress its rotational speed and prevent the spill ring 62 from moving at high speed.

As shown in the figure, the dashpot DP is composed of a piston 1 that projects within the rotation locus of the tension lever 63, and a housing H in which a pressure chamber 1a is hermetically partitioned by the piston 1. An example is shown in FIG.

In the figure, the housing H is a cylindrical body with one end closed, and a piston 1 is fitted into both openings so as to be able to move forward and backward, and is biased to protrude by a coil spring 12. A pressure chamber 1a is formed.

A throttle passage 11 is formed through the piston 1 to communicate the pressure chamber 1a and the fuel chamber S.

Thus, the tension lever 63 is connected to the piston 1.
When it comes into contact with the piston 1, the piston 1 is pushed back, but
The retreating speed is such that the fuel in the pressure chamber la is a throttle flow Il@11
The rotational speed of the tension lever 63 is thereby reduced, the spill ring 62 returns with time, and surging is prevented from occurring.

An example of a fuel injection amount adjusting device provided with this type of dashpot is shown in Japanese Utility Model Application No. 61-14732.

[Problem to be solved by the invention J: The above-mentioned conventional fuel F4! Although the IF irradiation device effectively prevents surging during vehicle deceleration as described above, this dashpot effect may be rather inconvenient in the engine idle speed range.

That is, in the idle state where the throttle lever 65 is returned to its original position, speed regulation is performed by the governor sleeve 67, but at this time, the tension lever 63 and the control lever 6
8 and the spill ring 62 vibrate slightly due to the action of injection reaction force, etc., and the fuel injection amount is determined by the spill ring 62.
determined by the median amplitude of However, when the tension lever 63 comes into contact with the piston 1 of the dashpot DP, the tension lever 63 moves in the direction of pushing the piston 1.
Since the free vibration of the piston 1 is suppressed, the vibration amplitude varies depending on the state of contact with the piston 1, which causes a variation in injection characteristics and causes problems such as rotation skipping. Furthermore, under certain conditions, the dashpot effect may become too strong, causing problems such as deterioration of the effectiveness of engine braking.

The present invention solves this problem, and aims to provide a fuel injection amount adjustment device for a fuel injection pump that does not cause fluctuations in idle rotation and has a dashpot effect of the required amount in the required area. do.

[Means for Solving the Problems J] The present invention will be described in detail: a control lever that is directly connected to a spill ring to move it and that the tip of the governor sleeve abuts; and a control lever that is connected to the control lever via a spring. and a tension lever connected to the throttle lever via another spring;
A fuel injection amount adjustment device for a fuel injection pump comprising a dashpot that abuts the tip of a control lever or a tension lever to suppress the rotation speed of the lever in the direction of decreasing the injection amount, the dashpot comprising:
A piston that is pressed by the rotating tip of the control lever or tension lever, and a piston that is sealed and partitioned by the piston and communicates with the fuel chamber in the fuel injection pump through a throttle passage, and is pushed back by the piston. a pressure chamber in which the internal pressure rises due to the pressure, and a bypass flow path is provided that allows the pressure chamber to communicate with the fuel chamber S without resistance, and the bypass flow path is provided with an on-off valve that opens in a predetermined rotation range of the engine. It is something that

[Operation] In the device configured as described above, the on-off valve opens in the idling rotation range of the engine, and as a result, the pressure chamber behind the piston is communicated with the fuel chamber without resistance through the bypass flow path.

Therefore, when the rotating tip of the control lever or tension lever comes into contact with the piston and pushes it in, the fuel in the pressure chamber freely flows out into the fuel chamber, and the internal pressure of the pressure chamber does not rise. As a result, the piston can freely move backward, and the vibration of the tension lever is not restricted, so that the injection characteristics do not fluctuate and engine rotation skipping is effectively prevented.

When the engine speed increases and leaves the idle speed range, the on-off valve closes. In this state, when the rotating tip of the tension lever comes into contact and the piston is pushed in, the internal pressure in the pressure chamber increases, and the fuel in the pressure chamber flows out through the throttle channel, exerting a dashpot effect.

[First Embodiment] In FIG. 1, a cylindrical recess 32 is formed in the side wall 3 of the pump housing, and the piston 1 is slidably fitted into the recess 32, and is sealed by the piston base. recess 3
Inside 2 is a pressure chamber 1a. The piston 1 has a contact surface for the tension lever 63 formed at its tip exposed from the recess 32 into the fuel chamber S, while its base is formed into a cylindrical shape and is connected to the end wall of the recess 32. A weak coil spring 12 is provided. Inside the tip of the piston 1 is a small-diameter throttle channel 1 that communicates the pressure chamber 1a and the fuel chamber S.
1 is formed.

A cylindrical recess 33 having a slightly small diameter and extending horizontally is formed in the pump housing side wall 3 at a position below the pressure chamber 1a, and a spool valve 2 as an on-off valve is slidably inserted into the recess 33. is the provision. One end face of the spool valve 2 faces the fuel chamber S, and a coil spring 22 is provided between the other end face and the end wall of the recess 33. The space in which the coil spring 22 is disposed communicates via a communication passage 34 to the low-pressure suction side of a feed pump (not shown) that supplies fuel to the fuel chamber S.

A bypass flow path 31 is formed in the side wall 3 that connects the pressure chamber 1a and the fuel chamber S through the recess 33, and the bypass flow path 31 allows fuel to flow between the two chambers 1a and 8 without resistance. It is of sufficient diameter.

Here, when the engine speed is in a low idling speed range, the pressure in the fuel chamber S is low, and the spool valve 2 is held at the forward position shown in the figure by the coil spring 22, and the spool valve 2 is held at the forward position shown in the figure by the coil spring 22, The formed communication port 21 corresponds to the bypass passage 31 and opens it.

In this idle rotation range, when the tension lever 63, which vibrates minutely to perform a control operation, comes into contact with the piston 1, the pressure chamber 1a is communicated with the fuel chamber S through the nose flow path 31. The piston 1 moves into and out of the recess 32 without resistance in response to the vibration of the tension lever 63,
It doesn't interfere with the vibration. Fluctuations in the injection characteristics are thus prevented.

When the engine speed increases, the internal pressure of the fuel chamber S increases, and in response to this pressure, the spool valve 2 is pushed into the recess 33 against the spring force of the coil spring 22 (
On the right side of the figure), the communication boat 21 is removed from the bypass channel 31 and this is closed.

In this state, when the tension lever 63 comes into contact with the piston 1 at high speed due to deliberate deceleration, etc., the internal pressure of the pressure chamber 1a rises rapidly due to the retraction of the piston 1, and the fuel in the pressure chamber 1a flows out through the throttle channel 11. , suppresses rapid movement of the tension lever 63. This prevents surging and the like from occurring.

[Second Embodiment] In the first embodiment, the spool valve 2 is moved by the pressure difference between the two end faces of the spool valve 2, but it can also be driven by an electromagnetic coil 4 as shown in FIG. That is, in the figure, an electromagnetic coil 4 is provided on the side wall 3 of the pump housing, and when the spool valve 2 is not energized, the coil spring 22 holds the spool valve 2 at the forward end as shown in the figure, and the communication boat 21 connects the bypass passage 31. It's open. When the electromagnetic coil 4 is energized, the spool valve 2 is attracted by the electromagnetic coil 4 and moves to the right in the figure, and the communication port 21 is removed from the bypass passage 31 and closed.

The electromagnetic coil 4 is connected to an external energization control circuit 15, and the circuit 5 integrates information such as engine speed, engine load, transmission position, vehicle speed, etc., and sets the electromagnetic coil in the idle rotation range suitable for the vehicle. 4 and cancels the dashpot action to prevent rotational skipping, etc.

[Effects of the Invention] As described above, according to the fuel injection amount adjusting device of the present invention, by eliminating the dashpot effect in the engine idling rotation range, free vibration of the control lever or tension lever is allowed, and It is possible to effectively prevent the occurrence of rotational skipping, etc.

[Brief explanation of drawings]

1 and 2 are sectional views of main parts showing the first and second embodiments of the device of the present invention, FIG. 3 is an overall sectional view of a conventional device, and FIG. 4 is an overall sectional view of a conventional dashpot. be. 1... Piston 1a... Pressure chamber 11... Throttle flow path 2... Spool valve (on/off valve) 31... Bypass flow path 34... Communication path 4... Electromagnetic coil 5... - Energization control circuit 62... Spill ring 63... Tension lever 65... Throttle lever 67... Governor sleeve 68... Control lever DP... Tarash pot S... Fuel chamber Fig. 1 Fig. 2 figure

Claims (1)

[Claims] A control lever that is directly connected to the spill ring to move it and that the tip of the governor sleeve comes into contact with; and a tension lever that is connected to the control lever via a spring and to the throttle lever via another spring. A fuel injection amount adjusting device for a fuel injection pump comprising a lever and a dashpot that suppresses the rotational speed of the control lever or the tension lever in the direction of decreasing the injection amount, wherein the dashpot is connected to the control lever. Alternatively, the tip of the tension lever contacts and presses a piston, and the piston forms a hermetically sealed section, which communicates with the fuel chamber in the fuel injection pump through a throttle passage, and the internal pressure increases as the piston is pushed back. The engine is characterized by comprising a pressure chamber and a bypass flow path that communicates the pressure chamber with the fuel chamber without resistance, and the bypass flow path is provided with an on-off valve that opens in a predetermined rotation range of the engine. Fuel injection amount adjustment device for fuel injection pump.