JPH0121154Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel stop device for a distributed fuel injection pump, and particularly provides a device that does not generate unpleasant vibrations when an engine mounted on a vehicle is stopped.

The diesel engine stopping mechanism is A.
Mechanisms that close the intake shutter to cut off the supply air, or B. mechanisms that instantly cut off the fuel are known.

In case A, the air supply is cut off while the fuel is being supplied, so that combustion within the engine gradually decreases and the engine stops. Therefore, the rotation of the engine gradually decreases and comes to a stop, so that vibrations that cause discomfort to the occupants of the vehicle equipped with this engine are not generated, and so-called good feeling is achieved.

On the other hand, B instantly cuts off the fuel supply while leaving the supplied air unchanged, so the engine suddenly stops.
As a result, severe vibrations occur when the engine is stopped, and the occupants of the vehicle feel the unpleasant vibrations, resulting in a poor feeling.

Mechanism A is such that air is not supplied in proportion to a certain amount of fuel supplied, and engine stoppage occurs as combustion by the fuel gradually disappears. Therefore, if we conversely reduce the amount of fuel supplied when the engine is stopped,
The output of the engine is gradually reduced, and when the amount of fuel supplied is finally below the engine stall limit, the engine stops without incomplete combustion.

Furthermore, Japanese Patent Publication No. 51-10305 describes a control device that delays the stopping operation when the engine is stopped in an in-line fuel injection pump for a diesel engine with an exhaust turbo supercharger. Since the oil retainer is communicated with the atmosphere via a breather, the oil inside may deteriorate, causing premature wear of the free piston and spring, or changing the adjustment pressure of the cylinder device.

Furthermore, in the above-mentioned control device, since the set force is given to the fuel adjustment rack by the spring of the cylinder device, it is necessary to change the set force of the governor spring connected to the rack in multiple stages, which is not easy to do. It is something.

Further, Japanese Utility Model Application Publication No. 55-106362 describes a fuel cutoff device in which a cutoff valve is installed in the fuel intake passage by an electromagnetic coil and closed by a spring. ,
An electronically controlled fuel injection device is described that changes the amount of fuel in the following manner when the fuel is cut and restored: gradually decrease → interrupt → gradually increase → normal injection. This fuel stop device is not a simple structure in which the shutoff valve returns to the closed position at a slow speed using a delay device.

The present invention was obtained based on the above-mentioned knowledge, and can be said to be a combination of the advantages of the above-mentioned engine stop devices A and B.

Therefore, the present invention aims to solve the above-mentioned drawbacks of the prior art by providing a shutoff valve that opens with an electromagnetic coil and closes with a spring in the fuel intake passage connecting the inside of the pump housing and the pressure chamber at the top of the plunger. A delay device is connected to the above-mentioned shutoff valve, and includes a piston fitted with a check valve and an orifice slidably inserted into a cylinder sealed with oil, and the spring is released when the engine is stopped. The present invention is characterized in that the shutoff valve, which returns to the closed position by the applied force, is limited to a slow speed by the delay device.

Next, embodiments of the present invention will be described with reference to the drawings.

The figure is a cross-sectional view of the main parts of a distribution type fuel injection pump, showing a plunger pump P as a fuel pressure feeding mechanism and a cutoff valve V provided in a passage for supplying fuel to the plunger pump P in cross section.

Reference numeral 1 denotes a pump housing in which a vane pump and a cam mechanism for driving the plunger 3 are provided, although not shown.

A plunger 3 is slidably fitted into the cylinder 2 of the pump housing 1. The plunger 3 is rotated in the direction of arrow A by a shaft driven by an engine (not shown), and is further reciprocated in the direction of arrow B by the cam mechanism, so that the plunger 3 is moved through the suction passage 5. 3
Fuel is drawn into the upper pressure chamber 4 and discharged to supply each fuel injection valve.

A cutoff valve V is provided in the fuel intake passage 5 to open and close the intake port 5' at the entrance of the pressure chamber 4.
Reference numeral 6 denotes a valve body with an iron core 7 attached thereto, and a spring 8 provided above the iron core 7 to apply a closing force to the valve body 6. Further, a solenoid coil 9 is provided around the iron core 7, and this solenoid coil 9
is connected to a key switch 10 and a battery 11.

Casing 1 surrounding the outer periphery of solenoid coil 9
A cylinder 13 is provided at the upper part of the piston 2, and a piston 15 connected to the iron core by a rod 14 is slidably fitted into the cylinder. The piston 15 is provided with an orifice 15a, a check valve 15b that allows flow from the upper chamber 15d to the lower chamber 15e, but blocks it in the opposite case, and a hole 15c that is opened and closed by the check valve 15b. Further, the inside of the cylinder 13 is filled with oil L in a sealed manner so as not to communicate with the atmosphere, and a dart pot type delay device T is constituted by the combination of these respective members.

The orifice 15a is determined in consideration of the time during which the engine output gradually decreases without generating abnormal vibrations when the engine is stopped.

Next, the operation of the device according to the present invention will be explained.

While the engine is running, the key switch 10 is turned on and the solenoid coil 9 is energized.
The iron core 7 rises against the elastic force of the spring 8, and the valve body 6 opens the suction port 5'.

As the valve body 6 rises, the piston 15 rises and pressurizes the upper chamber 15d, so the oil contained there passes through the hole 15c and the orifice 15a, displaces the check valve 15b, and flows into the lower chamber 15e. do.

When the plunger 3 reciprocates as shown by arrow B with the valve body 6 raised and the suction port 5' opened as described above to pressurize the fuel in the pressure chamber 4, the fuel flows through the passages 3a and 16. Delivery valve 1 through
7 is opened, the fuel is supplied to the fuel injection nozzle communicating with the passage 18, and is injected into the combustion chamber. Also,
When the plunger 3 rotates as shown by arrow A and matches a passage other than the passage 16, fuel is sequentially distributed and supplied to the fuel injection nozzle connected to that passage, as in the conventional device. It is.

Next, the operation when the engine is stopped will be explained.

First, when the key switch 10 is turned off, the solenoid coil 9 is demagnetized, and the elastic force of the spring 8 causes the iron core 7, that is, the valve body 6, to descend and close the suction port 5'. During this downward movement of the valve body 6, the check valve 15b comes into close contact with the piston 15 due to the resistance of the oil and closes the hole 15c. Therefore, the oil in the lower chamber 15e of the cylinder 13 moves to the upper chamber 15d only through the orifice 15a. This orifice 15a does not generate abnormal vibrations when the engine is stopped, and the engine stops while the output is gradually reduced, so that the engine stops with good feeling without generating unpleasant vibrations.

As detailed above, the present invention provides a shutoff valve that opens with an electromagnetic coil and closes with a spring in the fuel intake passage connecting the inside of the pump housing and the pressure chamber at the top of the plunger, and fills the oil in a sealed manner. A delay device consisting of a piston with a check valve and an orifice slidably inserted into the cylinder is connected to the shutoff valve, and the shutoff device returns to the closed position by the biasing force of a spring when the engine is stopped. Since the valve is limited to a slow speed by the delay device described above, the shutoff valve, which returns to the closed position by the force of the spring when the engine key switch is turned OFF, is limited to a slow speed by the connected delay device. Therefore, the fuel can be gradually reduced from the open position to the closed position of the shutoff valve.

Furthermore, since the delay device is connected to a shutoff valve for shutting off the fuel suction passage, it can be easily implemented without the need to particularly change the governor characteristics of the fuel injection pump, and it also prevents oil from entering the cylinder. Since it is filled in a hermetically sealed manner, it has the advantage of preventing wear of the piston and spring and changes in set-up due to oil deterioration, thereby making it possible to construct a highly reliable fuel stop device.

Therefore, according to the present invention, the fuel is not abruptly cut off when the engine is stopped, so the engine does not generate unpleasant vibrations and can be stopped smoothly. Furthermore, even if the fuel is throttled, the intake air is not throttled, so incomplete combustion does not occur and smoke does not occur.

[Brief explanation of the drawing]

The figure is a front sectional view showing the main parts of the fuel stop device for a distribution type fuel injection pump according to the present invention. P...Plunger pump, V...Shutoff valve, T...
...Delay device, 1... Pump housing, 2... Cylinder, 3... Plunger, 4... Pressure chamber, 5... Suction passage, 5'... Suction port, 6...
... Valve body, 9 ... Solenoid coil, 10 ... Key switch, 13 ... Cylinder, 14 ... Rod,
15... Piston, 15a... Orifice, 15
b...Check valve, 15c...hole, 15d...upper chamber,
15e...lower room.

Claims (1)

[Scope of utility model registration request] A shutoff valve is installed in the fuel intake passage connecting the inside of the pump housing and the pressure chamber at the top of the plunger, which opens with an electromagnetic coil and closes with a spring.A check valve and orifice are installed in the cylinder that is sealed with oil. a delay device having a piston slidably fitted therein is connected to the shutoff valve;
A fuel stop device for a distribution type fuel injection pump, in which the shutoff valve, which returns to the closed position by the biasing force of a spring when the engine is stopped, is limited to a slow speed by the delay device.