JPH05288133A - Flow rate controller of volume type pump - Google Patents

Abstract

PURPOSE:To miniaturize a solenoid valve and improve its responsiveness by decreasing force requited for opening/closing the solenoid valve. CONSTITUTION:A solenoid valve 10 which controls discharge flow rate by opening/closing is provided in a pump suction passage 20 in a volume type pump 1 which sucks and discharges fluid by reciprocating movement of a plunger 4. A valve 15 which opens separately from a valve seal 17 by the movement of ordinary direction and closes by making contact with the valve seal 17 by the movement of the opposed direction, is provided in the solenoid valve 10. Pressure in a pump chamber 2 is activated in valve closing direction to a valve 15 at the time of closing the solenoid valve 10, and suction pressure of the pump is activated to the valve 15 at the time of opening the valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for a positive displacement pump used in a high pressure fuel pump for pressure-feeding fuel to a fuel injection nozzle in a fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional example of a flow rate control device for a positive displacement pump, for example, there is one disclosed in Japanese Patent Laid-Open No. 61-65071. This publication discloses that in a positive displacement pump that sucks and discharges fluid by the reciprocating motion of a plunger, an electromagnetic valve that causes the fluid in a pump chamber of the pump to leak by opening the valve and stops the fluid leakage by closing the fluid is provided. It is provided.

[0003]

According to the above-mentioned conventional example,
As the solenoid valve that opens (opens) the solenoid valve during discharge and releases the flow rate that does not require discharge, the internal valve solenoid valve that opens by retracting the valve is used.
A valve closing force is required to overcome the pressure of the pump chamber and close the valve of the solenoid valve during discharge. Therefore, since the valve closing force required for the solenoid valve becomes large, the solenoid valve becomes large and the responsiveness also deteriorates.

Therefore, the present invention has been made to solve the above-mentioned problems, and the purpose thereof is to reduce the force required to open and close the solenoid valve, to reduce the size of the solenoid valve and to improve the responsiveness. It is to provide a flow rate control device for a positive displacement pump capable of achieving the above.

[0005]

The present invention for solving the above-mentioned problems is constructed as follows. The flow rate control device for a positive displacement pump according to claim 1 is a positive displacement pump that sucks and discharges a fluid by reciprocating motion of a plunger, and a solenoid valve that controls a discharge flow rate by opening and closing the pump suction passage is provided. The solenoid valve is provided with a valve that separates from the valve seal to open when operated in the forward flow direction, and abuts against the valve seal to close when operated in the reverse flow direction.

According to a second aspect of the present invention, there is provided a flow rate control device for a positive displacement pump, which sucks and discharges a fluid by reciprocating a plunger and has a feed pump in a pump suction passage. An electromagnetic valve is provided that causes the fluid in the pump chamber to leak through the spill pipe by opening the valve and stops the leakage of the fluid by closing the valve. Further, a valve that opens apart from the valve seal by the operation in the reverse flow direction is provided, and the spill pipe is provided with a regulator that adjusts the pipe internal pressure. Further, in a flow rate control device for a positive displacement pump according to a third aspect, in the second aspect, the spill pipe is joined upstream of the regulator and downstream of the feed pump in the pump suction passage.

[0007]

According to the means of the first aspect, when the solenoid valve is open, the plunger is lowered from the top dead center so that the fluid is sucked into the pump chamber of the positive displacement pump. Subsequently, the plunger moves up from the bottom dead center, whereby the fluid in the pump chamber is made to flow backward. When the solenoid valve is closed midway, the fluid in the pump chamber is pressurized and discharged from the pump discharge port. At this time, the pressure of the pump chamber acts on the valve of the solenoid valve in the valve closing direction. Again, when the plunger descends from the top dead center, the solenoid valve is opened to suck the fluid into the pump chamber. At this time, the suction pressure of the pump acts on the valve of the solenoid valve in the valve opening direction.

According to the second aspect of the invention, in the closed state of the solenoid valve, the fluid is sucked and discharged by the reciprocating motion of the plunger, and the fluid is filled in the pump chamber by the feed pump. The discharge flow rate is controlled by releasing the flow rate that does not need to be discharged by opening the solenoid valve during the discharge of the fluid. Further, when the solenoid valve is closed, the pressure of the pump chamber acts on the valve in the valve closing direction, and when the valve is opened, the fluid pressure trapped by the regulator in the valve acts in the valve opening direction. Further, according to the means described in claim 3, when the solenoid valve is opened, the valve can apply the pressure from the spill pipe side by the feed pump in the valve opening direction.

[0009]

Embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] In FIG. 1, which schematically shows a flow rate control device of a positive displacement pump used for a fuel injection device of an internal combustion engine, a pump chamber 2 is formed in a pump body 1a of the positive displacement pump 1. There is. A plunger 4 is incorporated in the cylinder 3 communicating with the pump chamber 2 such that the plunger 4 can reciprocate. A roller 5 rotatably attached to a lower end portion of the plunger 4 rolls along an outer peripheral cam surface 7 of a cam shaft 6 which is positively rotated by a rotary drive source, and thereby a vertical movement is given. In FIG. 1, the state where the plunger 4 is at the top dead center is shown by a solid line, and the state where the plunger 4 is at the bottom dead center is shown by a chain double-dashed line. A pump discharge passage 8 having a check valve 9 communicates with the pump chamber 2. The check valve 9 allows only the flow in the discharge direction of the pump discharge passage 8 which is equal to or higher than a predetermined discharge pressure.

A solenoid valve 1 is provided on the upper surface of the pump body 1a.
0 is attached. The electromagnetic valve 10 includes a valve body 11 forming a passage 12, a core 13 housed in the valve body 11 and wound with an electromagnetic coil 14, and a magnetic valve 1 that is pulled up by energizing the electromagnetic coil 14.
5, a valve spring 16 for urging the valve 15 in the protruding direction (downward in the drawing), and a valve seal 17 that is closed by contact of the valve portion 15a of the valve 15 and opened by separation. The valve body 11
The pump suction passage 20 is communicated with the passage 12 of the above, and the suction passage 20 is communicated with the inside of the fuel tank 21.

In the electromagnetic valve 10, when the electromagnetic coil 14 is not energized, the valve 15 has a valve spring 16
Is urged in the forward flow direction of the passage 12 (the flow direction from the tank side to the pump chamber) by the elasticity of the valve 12, the valve portion 15a of the valve 15 separates from the valve seal 17 and opens (two points shown in the figure). See the chain line). At this time, the protruding portion 18 of the valve 15 contacts the stopper portion 11 a of the valve body 11. When the electromagnetic coil 14 is energized, magnetic flux flows through the core 13 and the valve 15, which are magnetic bodies, so that the valve 15 is pulled up against the elasticity of the valve spring 16 and the valve portion 15a of the valve 15 is closed.
7 and the valve is closed (see the solid line in the figure). Solenoid valve 1
The energization of the electromagnetic coil 14 of 0 is controlled by inputting an energization signal by the solenoid valve controller 19 including an electronic control unit.

The operation of the flow rate control device for the positive displacement pump will be described with reference to the timing chart of FIG. When the plunger 4 descends from the top dead center, the pump is in the suction stroke and the solenoid valve 10 is open. Therefore, the fuel in the fuel tank 21 is sucked into the pump chamber 2 from the pump suction passage 20. When the plunger 4 rises from the bottom dead center, the solenoid valve 10 is open, the discharge side pressure is high, and the check valve 9 is closed. Therefore, as the plunger 4 rises, the fuel in the pump chamber 2 is discharged from the pump suction passage 20. Fuel tank 21
It flows back to and is released (release process).

When the solenoid valve 10 is closed by the energization signal from the solenoid valve controller 19 at the timing T corresponding to the flow rate required on the discharge side, the pressure in the pump chamber 2 rises, and the pressure is equal to or higher than a predetermined pressure. When, the check valve 9 is opened and the required flow rate is discharged toward the discharge side (so-called injector) through the pump discharge passage 8 (discharge stroke). When the solenoid valve 10 is closed, the pressure in the pump chamber 2 acts on the valve 15 in the valve closing direction, so that the force (magnetic attraction force) generated to keep the solenoid valve 10 closed is small. .. It should be noted that among the flow rates pushed out from the pump chamber 2 in the ascending process of the plunger 4, the discharge flow rate from the bottom dead center of the plunger 4 to the timing T is the flow rate which flows back into the fuel tank 21 and is released, and from the timing T the top dead The discharge flow rate up to the point is the flow rate discharged to the discharge side.

Further, when the plunger 4 reaches the top dead center,
The plunger 4 descends again, and at the same time, the energization signal from the solenoid valve controller 19 disappears, so that the solenoid valve 10
Is opened and the suction stroke is started, the pressure in the pump chamber 2 becomes negative, and the suction pressure of the fluid acts on the valve 15 in the opening direction. Therefore, the load of the valve spring 16 that attempts to open the solenoid valve 10 can be small. Therefore,
The force required for the solenoid valve 10 is smaller than that of the conventional one, and a solenoid valve having a small size and excellent responsiveness can be used.

[Second Embodiment] A second embodiment will be described with reference to the schematic diagram of FIG. In the second embodiment, the parts which are considered to be the same as or equivalent to those in the first embodiment are designated by the same reference numerals in the drawings, and the duplicated description will be omitted. Further, the same concept is applied to the following embodiments, and a duplicate description will be omitted. In this example, in order to enhance the fuel filling efficiency and stabilize the discharge efficiency during high-speed operation of the positive displacement pump 1, the feed pump 24 that feeds the fuel into the pump chamber 2 under pressure.
Is provided. That is, unlike the first embodiment, the pump suction passage 20 is communicated with the pump chamber 2, and
An in-tank feed pump 24 is provided at the suction end. Further, the pump suction passage 20 is provided with a suction side check valve 25 which allows only a flow in the pumping direction of a predetermined pressure or more. Further, the pump suction passage 20
A return passage 26 returning to the fuel tank 21 is branched upstream of the check valve 25, and the return passage 2
6 is provided with a regulator 27 for adjusting the pressure in the suction passage 20 to a constant adjusted feed pressure.

In the passage 12 of the solenoid valve 10, the first embodiment is used.
Instead of the pump suction passage 20, a spill pipe 28 returning to the fuel tank 21 is communicated. In the spill tube 28,
A regulator 30 for adjusting the pressure inside the tube is provided. The pressure regulated by the regulator 30 is about the same as the regulator 27 in the pump suction passage 20.

In the flow rate control device of the positive displacement pump, when the plunger 4 descends from the top dead center when the solenoid valve 10 is closed, the positive displacement pump 1 is in the suction stroke, and therefore the pressure in the pump chamber 2 is reduced. The discharge side check valve 9 is closed and the suction side check valve 25 is opened accordingly, so that the fuel tank 2 enters the pump chamber 2.
1 fuel is inhaled. At this time, the fuel is fed by the feed pump 24 and filled in the pump chamber 2, so that the efficiency of filling the pump chamber 2 with the fuel is enhanced.

Then, when the plunger 4 rises from the bottom dead center, the positive displacement pump 1 is in the discharge stroke, so that the pressure in the pump chamber 2 rises, and the suction side check valve 25 closes accordingly. By opening the discharge side check valve 9, the fuel in the pump chamber 2 is discharged to the pump discharge passage 8. If the solenoid valve 10 is closed during the discharge stroke, the fuel in the pump chamber 2 can be pressurized because the fuel is not leaked. When the electromagnetic valve 10 is opened by energizing the electromagnetic coil 14, the fuel in the pump chamber 2 leaks to the fuel tank 21 through the spill pipe 28, so that the pressure of the fuel in the pump chamber 2 cannot be increased. Therefore, the discharge flow rate can be adjusted by controlling the opening / closing of the solenoid valve 10 by the solenoid valve controller 19.

When the solenoid valve 10 is closed, the pressure in the pump chamber 2 acts in the direction of closing the valve 15 as in the first embodiment, and therefore occurs to keep the solenoid valve 10 closed. Very little force (magnetic attraction) is required. Further, when the electromagnetic valve 10 is opened, the fluid pressure trapped in the passage 12 by the valve closing and the regulator 30 acts in the direction of opening the valve 15. Therefore, the load of the valve spring 16 that attempts to open the solenoid valve 10 can be small. Therefore, also in this example, as in the first embodiment,
The opening / closing pressure is well balanced, the force required for the solenoid valve 10 is small, and a solenoid valve having a small size and excellent responsiveness can be used.

A description will be added to this function and effect.
For example, as shown in FIG. 5, when the spill pipe 28 is not provided with the regulator 30, the spill pipe 2
Since 8 is opened to the atmosphere, the force Px acts on the valve 15 in the sealing direction when the solenoid valve 10 is closed. Therefore, the spring load of the valve spring 16 for opening the valve 15 is larger than the force Px. There is a need to. The force Px
Is the feed pressure P ₁ and the sealing area A of the valve 15 (see FIG.
(See the two-dot chain line A part), Px = P ₁ × A. Therefore, this force Px becomes an extra force in driving the valve 15, and the response of the solenoid valve 10 is deteriorated, or the solenoid valve 10 is increased in size.
However, according to the second embodiment, since the regulator 30 is provided in the spill pipe 28, the fluid pressure trapped in the passage 12 when the solenoid valve 10 is closed can be acted as the valve opening force of the valve 15. Spring 16
The spring load of can be reduced to the force Px or less, and the electromagnetic force can be small.
The effect is obtained.

[Third Embodiment] A third embodiment will be described with reference to the schematic diagram of FIG. In this example, the spill pipe 28 in the second embodiment is located upstream of the regulator 30.
It is joined to the downstream side of the feed pump of the pump suction passage 20, and the regulator 26 of the return passage 26 of the second embodiment is eliminated. According to this example, instead of the pressure confined in the passage 12 of the second embodiment, a pressure equal to the feed pressure can be applied to the passage 12 through the spill pipe 28, and this pressure is used as the valve opening force of the valve 15. Can be operated. Also in this example, the same operation and effect as those of the second embodiment can be obtained.

[0022]

The effects peculiar to the present invention are as follows. In the flow rate control device of the positive displacement pump according to claim 1, when the solenoid valve is closed, the pressure of the pump chamber acts on the valve in the valve closing direction, and when the valve is opened, the suction pressure of the pump acts on the valve. A small force is required for the solenoid valve, and a solenoid valve that is small and has excellent responsiveness can be used.

In the flow rate control device for a positive displacement pump according to a second aspect of the present invention, the pressure of the pump chamber acts on the valve in the valve closing direction when the solenoid valve is closed, and the valve is closed by the regulator when the valve is opened. Also, since the fluid pressure acts in the valve opening direction, the force required for the solenoid valve is small as in the first aspect, and the solenoid valve can be downsized and the responsiveness can be improved. In addition, claim 3
In the flow rate control device of the positive displacement pump described above, when the solenoid valve is opened, the valve can exert a pressure from the spill pipe side by the feed pump in the valve opening direction, and the same effect as in claim 2 can be obtained. can get.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a first embodiment.

FIG. 2 is a timing chart showing the opening / closing timing of a solenoid valve.

FIG. 3 is a schematic explanatory view of a second embodiment.

FIG. 4 is a schematic diagram illustrating a third embodiment.

FIG. 5 is a schematic diagram illustrating a comparative example of Example 2.

[Explanation of symbols]

 1 Positive displacement pump 2 Pump chamber 4 Plunger 10 Solenoid valve 15 Valve 17 Valve seal 20 Pump suction passage

Claims (3)

[Claims] 1. A positive displacement pump that sucks and discharges fluid by reciprocating a plunger, is provided with a solenoid valve for controlling a discharge flow rate by opening and closing the pump suction passage, and the solenoid valve operates in a forward flow direction. A flow control device for a positive displacement pump having a valve that separates from the valve seal and opens by the valve, and that abuts against the valve seal and closes by the operation in the reverse flow direction. 2. A positive displacement pump having a feed pump provided in a pump suction path, which sucks and discharges fluid by reciprocating a plunger, and causes fluid in a pump chamber of the pump to leak through a spill pipe by opening a valve. An electromagnetic valve that stops the leakage of the fluid by closing the valve is provided, and the electromagnetic valve opens by opening the valve seal by abutting against the valve seal and closing by the operation in the forward flow direction. A flow control device for a positive displacement pump, which is equipped with a valve that adjusts the internal pressure of the spill pipe. 3. The flow rate control device for a positive displacement pump according to claim 2, wherein the spill pipe is joined upstream of the regulator and downstream of the feed pump of the pump suction passage.