JPH063161Y2 - Fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a distributed fuel injection pump for a fuel injection type internal combustion engine, and more particularly to a fuel injection designed to prevent injection delay during acceleration, climbing, etc. Regarding the structure of the pump.

[Prior Art] A distribution type fuel injection pump used for a fuel injection type internal combustion engine such as a diesel engine is configured as shown in FIG. 4, for example, and fuel from a fuel tank is regulated by a feed pump 1. After the pressure is adjusted by the valve 2, the pressure is supplied to the inside of the pump 3, and the fuel is sent to the fuel injection nozzle by the plunger pump 6 via the roller 4 and the cam mechanism 5 and the delivery valve 7. Such a distributed fuel injection pump generally has a built-in hydraulic timer 8 that advances the fuel injection timing as the engine speed increases. The timer piston 9 of the timer 8 is biased by the timer spring 10, so that the suction side pressure of the feed pump 1 is introduced into the timer piston low pressure chamber 11 and the timer piston high pressure chamber
The pump internal pressure is introduced into the pump 12, and the increase in the pump internal pressure due to the increase in the engine speed causes the timer piston 9 to move to the left side in FIG. 4 to advance the fuel injection timing. The advance angle characteristic by the timer is set as the characteristic A in FIG. 5, for example. Note that the timer 8 part and the feed pump 1 part in FIG. 4 are expanded 90 degrees.

As a conventional technique capable of controlling the advance angle characteristic by the above-mentioned timer, Japanese Utility Model Application Laid-Open No. 57-184229 discloses a structure in which the set pressure of the valve spring 13 of the regulating valve 2 is changed according to the operating conditions of the engine. 55-1047
No. 34 discloses a structure in which the orifice diameter of the overflow valve 14 is changed according to operating conditions.

[Problems to be Solved by the Invention] In the distribution type fuel injection pump as shown in FIG. 4, the following problems may occur.

In a normal vehicle, the fuel tank is arranged in the rear part of the vehicle body, so that when the vehicle accelerates, an inertial force acts on the fuel in the fuel passage from the fuel tank to the fuel injection pump toward the rear of the vehicle, whereby the inlet of the feed pump 1 The pressure (suction side pressure) decreases. Even when climbing a slope, the fuel passage is tilted so that the rear side of the vehicle is lower, so that the fuel in the passage receives a force in the direction of returning to the fuel tank due to its own weight, and the inlet pressure of the feed pump 1 decreases.

When the fuel in the fuel passage receives a force toward the fuel tank in this way, the inlet pressure of the feed pump 1 drops and the air in the fuel becomes bubbles, causing cavitation in the feed pump 1 and the suction side of the feed pump 1. The pressure drop on the discharge side tends to be greater than the pressure drop. When this phenomenon occurs, the pressure balance on both sides of the timer piston 9 of the hydraulic timer 8 is different from that in the steady operation state,
Fuel injection is delayed. That is, in FIG. 5, the characteristic as in the region B is shown depending on the acceleration of the vehicle and the degree of climbing. At the time of acceleration or climbing, there is a problem that sufficient output cannot be obtained due to the delay in fuel injection, even though the operating state originally requires the most output.

To solve this problem, the technique disclosed in Japanese Utility Model Laid-Open No. 57-184229 or Japanese Utility Model Laid-Open No. 55-104734 is used to detect the operating state of acceleration or climbing and regulate the pump internal pressure based on the signal. Is possible, but requires complex control mechanisms.

INDUSTRIAL APPLICABILITY The present invention is a very simple improvement without adding a complicated control mechanism, and it is possible to naturally prevent an excessive decrease in pump internal pressure by utilizing the state of acceleration or climbing, and prevent fuel injection delay. The purpose is to

[Means for Solving the Problem] A fuel injection pump according to the present invention which meets this object has a feed pump for feeding fuel from a fuel tank into the pump, and a hydraulic timer for controlling fuel injection timing. In a distributed fuel injection pump in which the suction side pressure of the feed pump is led to one side of the timer piston of the timer and the pump internal pressure is led to the other side of the timer piston, the pump internal pressure is communicated with the pump to allow the fuel in the pump to escape. A pressure regulating valve having a valve body movable in the vehicle front-rear direction due to an inertial force acting on itself or its own weight, in a fuel passage capable of regulating the fuel passage, and a moving direction of the valve body toward the vehicle rearward is a direction in which the fuel passage is closed. It is arranged so that

The pressure regulating valve can also be used as the regulating valve in the conventional structure, and by arranging the regulating valve in the direction in which the relief fuel passage is closed when the valve body moves to the rear of the vehicle, the regulating valve of the present invention. A pressure valve can be configured. Further, the fuel passage capable of adjusting the pump internal pressure may be used as an overflow fuel passage of the fuel injection pump, and the fuel passage may be provided with a pressure regulating valve having the above function.

[Operation] In such a fuel injection pump, an inertial force that acts toward the rear of the vehicle acts on the valve body of the pressure regulating valve during acceleration, and the weight of the valve body acts on the valve body toward the rear of the vehicle when climbing. This inertial force or its own weight naturally acts depending on the driving conditions for acceleration and the vehicle attitude of climbing. When the valve body is moved in the direction toward the rear of the vehicle, the passage cross-sectional area of the fuel passage that can adjust the pump internal pressure is reduced, the outflow of fuel from the pump is suppressed, and the decrease in pump internal pressure is suppressed. Therefore, the timer piston is kept at the target control position, the advance angle decrease of the timer is suppressed, and the fuel injection delay is prevented.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a fuel injection pump according to a first embodiment of the present invention. In this embodiment, except for the regulating valve 21 portion, it is substantially the same as the conventional structure shown in FIG.
Constitutes the pressure regulating valve in the present invention. Therefore, the description of the other components of the fuel injection pump will be omitted by assigning the same reference numerals as those in FIG. 4 to the components corresponding to those in FIG.

In FIG. 1, the feed pump 1 part, the regulating valve 21 part, and the timer 8 part are shown as a 90-degree development view in which the angle is changed by 90 degrees with respect to the other components.
In the regulating valve 21 portion in FIG. 1 which is partially expanded by 90 degrees, the arrow X direction is the vehicle front and the arrow Y direction is the vehicle rear.

Fuel is pressure-fed from the discharge side of the feed pump 1 into the pump 3 through the fuel passage 22, but the fuel passage 22 is branched to supply the fuel to the suction side of the feed pump 1 through the relief fuel passage 23. It communicates with the inlet side fuel passage 24 that leads.
Therefore, the relief fuel passage 23 communicates with the inside of the pump 3 through the fuel passage 22 and constitutes a fuel passage capable of adjusting the pump internal pressure by allowing the fuel in the pump to escape.
The relief fuel passage 23 is provided with a regulating valve 21 as a pressure regulating valve.

The regulating valve 21 is provided with a valve body 25 and a spring 26 for urging the valve body, and the valve body 25 slides in the vehicle front-rear direction (X-Y direction) due to inertial force acting on itself or its own weight. Held possible. A communication passage in the spring chamber 27
The pressure on the inlet side of the feed pump is introduced via 28. Basically, the pressure applied by the spring 26 and the pressure on the feed pump discharge side (pump inner pressure) introduced from the opposite side. The position of the valve body 25 is determined by the balance, but when inertial force or own weight acts on the valve body 25, the balance is also taken into consideration. Then, the direction Y in which the valve body 25 is directed toward the rear of the vehicle
When the valve is moved to, the relief fuel passage 23 is closed or the passage cross-sectional area is narrowed at the opening / closing portion 23a.

In the embodiment apparatus configured as described above, the regulating valve 21 is used during acceleration of the vehicle, particularly during sudden acceleration.
An inertial force in the direction toward the rear of the vehicle acts on the valve body 25 of. Further, when the vehicle is climbed, the vehicle leans so that the rear portion of the vehicle is lower, so that the weight of the valve body 25 acts in the direction of moving the valve body 25 toward the rear of the vehicle. When the valve body 25 is moved in the direction Y toward the rear of the vehicle by this inertial force or its own weight, that is, when it is moved from the position shown by the solid line in FIG. 2 to the position shown by the broken line, the valve of the regulating valve 21 is moved. The opening is reduced, the amount of fuel that escapes from the discharge side of the feed pump 1 to the inlet side fuel passage 24 via the relief fuel passage 23 is suppressed, and the pressure drop in the pump 3 is suppressed. Therefore, even if the inlet-side pressure of the feed pump 1 is reduced during acceleration or climbing, it is possible to prevent the pump internal pressure from being excessively reduced more than that amount. As a result, the timer piston 9
It is possible to prevent the pressure balance from both directions, that is, the pressure balance between the timer piston low pressure chamber 11 side where the feed pump suction side pressure is introduced and the timer piston high pressure chamber 12 side where the pump internal pressure is introduced, from being broken, and the timer piston 9
The advance angle control of the timer 8 by the movement of is substantially performed along the normal characteristic A in FIG. By controlling the advance amount reduction by the timer 8, the fuel injection delay is prevented.

It should be noted that although the pressure drop on the feed pump inlet side is small depending on the degree of acceleration or plate climbing, when the cavitation does not occur in the feed pump, the moving amount of the valve body 25 of the regulating valve 21 is also small, so It's not too horny.

Second Embodiment Next, FIG. 3 shows a second embodiment of the present invention.

In the present embodiment, the pressure regulating valve 31 is provided in the pump internal portion of the overflow fuel passage 32 of the fuel injection pump. In FIG. 3, the X direction indicates the direction toward the front of the vehicle, and the Y direction indicates the direction toward the rear of the vehicle. Since the parts other than the pressure regulating valve 31 and the overflow fuel passage 32 are substantially the same in structure as the conventional structure shown in FIG. 4, the parts corresponding to the parts shown in FIG. The same reference numerals as in FIG. 4 are attached.

The valve body 33 of the pressure regulating valve 31 is supported on the overflow shaft 34 so as to be slidable in the vehicle front-rear direction, and is sandwiched by the springs 35 and 36 from both sides, and is normally controlled to a position where the spring force is balanced. ing. Overflow shaft
An overflow fuel passage 32 for returning fuel to a fuel tank (not shown) is formed inside 34, and the fuel passage 32 and the pump interior 3 are communicated with each other through a communication hole 37. When the valve element 33 moves in the direction Y toward the rear of the vehicle,
The opening of the communication hole 35 can be reduced.

In such an embodiment device, due to the inertial force of the valve body 33 during acceleration of the vehicle, and due to the weight of the valve body 33 during climbing,
A force that moves the valve element 33 in the direction toward the rear of the vehicle naturally acts on each. When the valve body 33 moves in this direction, the opening area of the communication hole 35 is reduced, so that the amount of fuel flowing out to the overflow fuel passage 32 is suppressed and the pressure drop in the pump 3 is suppressed. Therefore, the reduction of the advance amount by the timer 8 is prevented. Other functions are the same as in the first embodiment.

Although the pressure regulating valve 31 is provided inside the pump in this embodiment, a pressure regulating valve having the same function can be provided outside the pump. In that case, the conventional fuel injection shown in FIG. 4 is used. All you have to do is change or add some parts to the outside of the pump.

[Advantages of the Invention] As described above, when using the fuel injection pump of the present invention, a pressure regulating valve having a valve body that can move in the vehicle front-rear direction due to inertial force or its own weight is provided, and the valve body is operated during acceleration and climbing. Since it is naturally moved toward the rear of the vehicle to suppress the escape of the pump internal pressure, it is a simple improvement, but it is possible to prevent the pump internal pressure from excessively decreasing even when the feed pump inlet pressure decreases. It is possible to prevent the advance amount of the timer from decreasing and prevent the fuel injection delay. Therefore, it is possible to prevent a decrease in output during acceleration and climbing. Further, at the time of acceleration or climbing, there is a possibility that fuel injection may be deteriorated, black smoke may be deteriorated, and exhaust temperature may be increased due to the injection timing being delayed as compared with the case of steady operation. However, these problems can be solved.

[Brief description of drawings]

FIG. 1 shows a fuel injection pump according to a first embodiment of the present invention,
FIG. 2 is a vertical cross-sectional view partially expanded and displayed at 90 degrees, FIG. 2 is an enlarged configuration diagram of a regulating valve portion of the fuel injection pump of FIG. 1, and FIG. 3 is a fuel injection pump according to a second embodiment of the present invention.
FIG. 4 is a vertical cross-sectional view partially expanded and displayed at 90 degrees, FIG. 4 is a vertical cross-sectional view partially expanded and displayed at 90 degrees of a conventional fuel injection pump, and FIG. 5 is a relationship diagram between a timer advance angle and an engine speed. 1 …… Feed pump 3 …… Inside pump 6 …… Plunger pump 7 …… Delivery valve 8 …… Timer 9 …… Timer piston 11 …… Timer piston low pressure chamber 12 …… Timer piston high pressure chamber 21 …… As a pressure regulating valve Regulating valve 23 …… Relief fuel passage 24 …… Inlet side fuel passage 25, 33 …… Valve body 31 …… Pressure regulating valve 32 …… Overflow fuel passage 34 …… Overflow shaft 37 …… Communication hole

Claims (1)

[Scope of utility model registration request] 1. A feed pump for feeding fuel from a fuel tank into the pump, and a hydraulic timer for controlling fuel injection timing. The suction side pressure of the feed pump is set to one side of a timer piston of the timer. Further, in the distribution type fuel injection pump in which the pump internal pressure is guided to the other side of the timer piston, the fuel passage works by communicating with the pump and allowing the fuel in the pump to escape to adjust the pump internal pressure. Fuel injection characterized in that a pressure regulating valve having a valve body that can move in the vehicle front-rear direction due to inertial force or its own weight is arranged such that the moving direction of the valve body toward the vehicle rear side is the direction that closes the fuel passage. pump.