JPS5934862B2 - Electromagnetic metering injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures the fuel discharged from the injection pump mainly to the diesel engine side by opening and closing a solenoid valve interposed between the fuel tank and the pump chamber of the injection pump. This invention relates to an electromagnetic metering injection pump.

Generally, in an injection pump that performs intermittent injection of fuel into the engine, the fuel inlet port that communicates with the pump chamber of the injection pump communicates with the pump chamber at the end of the suction stroke during the working stroke of the injection pump, and before the start of the pressure stroke. The structure is such that fuel in the pump chamber is prevented from flowing back to the suction port, and the fuel can be pumped to the discharge port under pressure.

A solenoid valve is interposed in the middle of the fuel flow path leading to this intake port,
Fuel pressurized to several atmospheres is applied to the inlet side of the solenoid valve, and a timed pulse generated by an electric control device is applied to the solenoid valve to determine the opening time of the solenoid valve according to the time width. An injection pump that measures fuel by determining the amount of fuel is described, for example, in Japanese Patent Publication No. 47-42406.

However, in such an injection pump, the total volume of the fuel flow path leading from the fuel outlet of the solenoid valve to the inlet of the injection pump, the timing of opening and closing of the solenoid valve, and the timing of communication with the fuel inlet of the injection pump are determined by the metering characteristics of the injection pump. It has been found that it has a significant impact on

In other words, if the sum of the fuel flow paths from the fuel outlet of the solenoid valve to the fuel inlet of the injection pump is relatively small, if the inlet of the injection pump is not communicating when the solenoid valve is opened, the solenoid The linearity of the metering characteristic, which determines the amount of fuel sucked into the pump chamber of the injection pump, ie, the amount of discharge from the injection pump, in response to the opening time of the valve cannot be achieved.

This means that the time that the injection pump's suction port communicates with the pump chamber is the maximum opening time that the solenoid valve can take, and the suction stroke of the injection pump's working stroke is the fuel metering time for the solenoid valve. This is the valve opening time, that is, the metering time, which can be used for the pumping process, but it is disadvantageous in terms of metering accuracy because it is not used as the metering time in the pressure feeding stroke.

For example, in a distributed injection pump for a 4-cylinder diesel engine, the operating angles of the suction and discharge strokes are equal, and the maximum rotational speed of the injection pump is 1800C! 1) If Inl, then one cycle of the working process will be X 1/4 = 0.008311 mecl, and the measurement time will be about 0.04 sec at most.

The delay time of the solenoid valve used for this type of measurement is 0.02
sec, making it difficult to measure with high precision.

One way to solve this problem is to add a volume corresponding to the discharge amount of the injection pump, that is, a stabilizing volume, to the flow path from the outlet of the solenoid valve to the suction hole of the injection pump, thereby increasing the metering time of the solenoid valve. A method has been proposed to extend the time taken up by one working stroke of the injection pump, but adding this stabilizing volume will worsen the response of the injection pump to the discharge rate change command, making it extremely difficult to In such cases, bunching may occur.

The present invention solves the above problem, and by disposing a pressure accumulating element with variable volume in a part of the flow path from the outlet of the solenoid valve to the inlet of the injection pump, the fuel metered each time by the solenoid valve is transferred to the pressure accumulator. The metering function of the solenoid valve can be realized over the entire cycle of the injection pump's working stroke, regardless of whether it is the suction stroke of the injection pump, and the metering time can be extended and the discharge amount change command can be It is an object of the present invention to provide an electromagnetic metering type injection pump which has good responsiveness to the injection pump.

The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 1, 1 is a fuel tank, 2 is a fuel supply pump, 3 is a pressure regulator, and 4 is a solenoid valve.As is well known, this solenoid valve 4 includes a needle valve 41, an excitation coil 42, a restoring spring 43, and a fuel outlet. 44, fuel population 45, and movable iron core 46.

Reference numeral 5 denotes an electrical control circuit that generates a timed pulse T for driving the electromagnetic valve 4 to open.

7 is an injection pump, and 6 is a pressure accumulating element with variable volume. The action chamber 63 having the restoring spring 62 is connected to the solenoid valve 4.
The outlet 44 temporarily stores the fuel metered by the solenoid valve 4.

The injection pump 7 is a distribution type injection pump using an inner cam, and its pressure feeding mechanism and distribution mechanism are well known, but an example of a 4-cylinder distribution type injection pump will be briefly described with reference to FIGS. 2 and 3. do.

FIG. 2 is a diagram illustrating the pressure feeding mechanism of the injection pump 7,
The same numbers as in FIG. 1 indicate the same parts.

The cam ring 28 in the pump housing has a four-mounted inner cam, inside which there is a pump shaft 64 stationary on the drive shaft of an engine (not shown), and two opposed pistons 26.
, 26' are rotated seven times while following the inner cam surface of the cam ring 28.

Therefore, the pistons 26, 26' perform suction and pressure strokes four times during one revolution of the pump shaft 64, and accordingly, fuel is pumped into the pump chamber 80 surrounded by the pistons 26, 26' and the pump shaft 64. is pumped and inhaled.

It goes without saying that the mulling 28 rotates within a certain angle range in response to an advance angle device (not shown).

FIG. 3 is a diagram illustrating the distribution mechanism of the injection pump 7,
The barrel 65 of the injection pump 7 is connected to the fuel outlet 44' of the solenoid valve 4.
one pump suction lower 0 leading to the pump and four discharge lowers 1, 72, 73, 7 leading respectively to the four delivery valves
It has 4.

The pump shaft 64 has four suction ports 75, 76, 77, 78 facing the suction lower 0, and a discharge lower 1,72°γ3.
, 74, and has one discharge port 79 facing the
These rotate within the distribution barrel 65 in an oil-tight fit with the pump shaft 64.

Discharge port 79 and suction ports 75, 76 of pump shaft 64
．． 77° 78 are all connected to the pump chamber 80 through a flow path, and when the piston 26, 26' is in the pumping stroke, the discharge port 79 and the four discharge lowers 1, 72, 73° 74
- is in communication with suction lower 0 and suction port 1-75,
Communication with 76.77.78 is cut off.

Further, during the suction stroke, one suction lower 0 communicates with any one of the four suction ports 75, 76, 77, and 78.

Therefore, fuel is pumped and distributed one after another from each discharge port 71, 72, 73, 74 to the four injection nozzles disposed in the engine.

In order to control the operation of the solenoid valve 4 in response to the operation of the injection pump 7, a rotation angle detector 9 is operatively coupled to the pump shaft 64 for generating an electrical timing signal every quarter rotation thereof. has been done.

The rotation angle detector 9 has a 4-pole inductor 91 fixed to the pump shaft 64 and a stator 92 made of a permanent magnet and a pick amplifier coil.
Generates an electrical timing signal every time it rotates.

This timing signal determines the opening timing of the solenoid valve 4, and the electric control circuit 5 generates a timed pulse T for driving the solenoid valve 4 every time the timing signal is applied from the rotation angle detector 9. do.

The time width of this timed pulse T is determined by various control parameters that determine the operating conditions of the engine, such as the fuel adjustment lever position,
The valve opening time of the solenoid valve 4 is determined from the fuel tank 1 to the injection pump 7.
Determine the amount of fuel supplied to

The operation of the above configuration will be explained below.

The solenoid valve 4 opens in response to a timed pulse from the electrical control circuit 5 corresponding to the planned fuel control characteristics of the engine, allowing metered fuel to flow from the inlet 45 to the outlet 44.

It goes without saying that the injection pump 7 should be in the suction stroke when fuel is measured by the solenoid valve 4, and the pump chamber 80 of the injection pump 7 should have a sufficient volume to accommodate the metered fuel. If so, it is sucked into the pump chamber 80 as it is, and in the subsequent discharge stroke, it is pumped out and injected into the engine.

However, if the opening time of the electromagnetic valve 4 becomes long and the suction lower 0 is not communicating with the pump chamber 80, or if the metered fuel cannot be accommodated in the pump chamber 80 even if it is communicating, the pressure accumulating element 6 is accommodated in the action chamber 63 and sucked into the pump chamber 80 in the next suction stroke.

Then, in the discharge stroke following this suction stroke, it is discharged and sent under pressure to the engine side.

By providing the pressure accumulating element 6 in this way, it is also possible to control the opening timing of the solenoid valve 4 regardless of the timing of the working stroke of the pump, and even in this case, metered fuel can be sucked into the pump chamber 80 during the suction stroke. Then, it is discharged and pressure-fed to the engine side during the discharge stroke.

That is, the maximum metering time by the solenoid valve 4 can be equal to the repetition period of the working stroke of the injection pump 7.

FIG. 4 is a diagram showing the main part of the fuel metering system in another embodiment of the present invention, in which the outlet 4 of the two solenoid valves 4° 4'
By introducing the fuel pressure on the 4, 44' side into the back pressure chamber 32 separated by the bellows 31 of the pressure regulator 3 of the fuel supply system, the inlet 45, 45' and outlet 44. 4
The configuration is such that the differential pressure with respect to 4 is kept constant.

Furthermore, by driving the two solenoid valves 4 and 4' to open alternately, the measuring time is doubled and the measuring accuracy is improved.

In this embodiment, the pressure accumulating element 6 has a bellows 66 and a restoring spring 64, and is capable of storing fuel in its action chamber 63, and operates in the same manner as in the previous embodiment.

In order to measure fuel using the two electromagnetic valves 4, 4', it is necessary to open each of them with a phase shift of half a period, and the configuration thereof is shown in FIG.

In FIG. 5, a stator 92' is provided separately from the stator 92 at a position shifted by 90 degrees, and this stator 92' is connected to an electric control circuit 5' for opening and driving the solenoid valve 4'. It is connected.

This configuration allows the solenoid valves 4, 4' to be opened alternately with a phase shift of half a cycle.

In the above embodiments, a distribution type pump has been described, but the objects of the present invention can also be achieved with a size type pump or the like.

As described above, in the present invention, in the electromagnetic metering injection pump, a pressure accumulating element with variable volume is arranged between the flow path from the outlet of the solenoid valve to the fuel intake port of the injection pump, and the metered fuel of the solenoid valve is adjusted. Since the pressure is temporarily stored in the pressure accumulating element and released from the pressure accumulating element during the next suction stroke of the injection pump, the pressure of the solenoid valve is temporarily stored and released from the pressure accumulating element during the next suction stroke of the injection pump. Each metered amount of fuel can be inhaled in each suction stroke of the injection pump,
Since the maximum value of the metering time of the solenoid valve can be as long as the operating cycle of the injection pump, there is an excellent effect that highly accurate fuel metering is possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, showing the pressure feeding mechanism of the injection pump used in the embodiment shown in FIG. , FIG. 3 is a schematic diagram showing the distribution mechanism of the injection pump used in the embodiment shown in FIG. 1, FIG. 4 is a configuration diagram of main parts in another embodiment of the present invention, and FIG. FIG. 2 is a schematic diagram of an electrical control section used in the embodiment. 1... Fuel tank, 4... Solenoid valve, 6
......Variable volume pressure accumulation element, 7...Injection pump H7()...Fuel inlet.

Claims (1)

[Claims] 1. Electromagnetic metering in which a solenoid valve is placed in the fuel flow path leading to the fuel inlet leading to the fuel tank and the pump chamber of the injection pump, and the amount of fuel sent from the fuel tank to the injection pump is measured by a timed pulse applied to the solenoid valve. What is claimed is: 1. An electromagnetic metering injection pump, characterized in that a variable volume pressure accumulating element communicating with the electromagnetic valve and the fuel flow path leading to the fuel inlet is provided.