WO2015182293A1

WO2015182293A1 - High-pressure fuel pump

Info

Publication number: WO2015182293A1
Application number: PCT/JP2015/062167
Authority: WO
Inventors: 宏泰城吉; 俊亮有冨; 徳尾　健一郎
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2014-05-28
Filing date: 2015-04-22
Publication date: 2015-12-03
Also published as: JP2015224587A

Abstract

The purpose of the present invention is to reduce the striking force of the movable element of a high-pressure fuel pump to thereby reduce operation noise caused by the striking of the movable element. A high-pressure fuel pump is provided with: a pressurizing chamber for pressurizing fuel; and an electromagnetic suction valve mechanism provided on the suction side of the pressurizing chamber and opening and closing a fuel passage located on the suction side. The high-pressure fuel pump is configured in such a manner that: the electromagnetic suction valve mechanism is provided with a movable section moved by magnetic attraction force; a cavity section, the volume of which is increased and decreased by the movement of the movable section, is formed on the outer peripheral side of the movable section; a fuel passage for supplying fuel from the cavity section toward the pressurizing chamber is formed; and the area of a flow passage for fuel discharged from the fuel passage decreases as the movable section is moved by magnetic attraction force.

Description

High pressure fuel pump

The present invention relates to a structure of an electromagnetic valve used for an electromagnetic suction valve for adjusting a fuel discharge amount in a high-pressure fuel pump, and a high-pressure fuel pump including the structure.

A high-pressure fuel pump that supplies pressurized fuel to an internal combustion engine can be used in a fuel supply system based on a direct injection operation in which fuel is directly injected into a combustion chamber of the internal combustion engine by an injector. Since the pressurized fuel directly injected into the combustion chamber of the internal combustion engine is pressurized and supplied by the high-pressure fuel pump, it is necessary to adjust the flow rate discharged from the high-pressure fuel pump according to the amount of fuel consumed.

For example, in Patent Document 1, the amount of high-pressure pumped fuel from the high-pressure fuel pump is adjusted by controlling the ON (energization) timing to the solenoid of the solenoid valve. Specifically, when the solenoid is turned on (energized) during the compression process by the piston plunger of the high-pressure fuel pump, the plunger rod moves away from the intake valve, and the intake valve is driven by the force of the spring and the pressure of the pressurized fuel. Moved to the closed position. When the piston plunger starts moving toward the bottom dead center and the pressure in the pressurizing chamber decreases, the plunger rod and the suction valve move in the valve opening direction. Patent Document 1 describes that by providing the second current supply region at this time, it is possible to reduce the collision noise caused by the collision between the plunger rod / suction valve and the valve stopper.

In Patent Document 2, it is described that the collision noise of the plunger rod can be reduced by setting a high value section and a low value section for the current supplied to the solenoid of the solenoid valve.

JP2013-32750A JP 2012-36886

Patent Document 1 and Patent Document 2 both relate to the reduction of operating noise of a high-pressure fuel pump. Particularly in passenger cars, when the engine is idling, the operating noise of the high-pressure fuel pump becomes noticeable, and efforts to find further noise reduction methods continue. Therefore, an object of the present invention is to reduce a collision force when a mover collides in a high-pressure fuel pump, and to reduce an operation sound caused by the collision of the mover.

In order to achieve the above object, the present invention provides a high pressure chamber comprising a pressurizing chamber for pressurizing fuel, and an electromagnetic suction valve mechanism provided on the suction side of the pressurizing chamber for opening and closing the fuel flow path. In the fuel pump, the electromagnetic suction valve mechanism includes a movable portion that moves by a magnetic attraction force, and a cavity portion that increases or decreases in volume due to the movement of the movable portion is formed on an outer peripheral side of the movable portion. A fuel flow path for supplying fuel is formed on the side of the pressurizing chamber, and the flow path area of the fuel discharged from the fuel flow path is configured to decrease as the movable portion moves by a magnetic attraction force. It is characterized by that.

According to the present invention, it is possible to reduce the collision force when the mover collides, and to reduce the operation sound caused by the collision of the mover. Other configurations, operations, and effects of the present invention will be described in detail in the following examples.

System schematic of the entire high-pressure fuel pump Cross section of high pressure fuel pump as seen from the front Detailed sectional view of the electromagnetic suction valve in the first embodiment of the present invention Detailed sectional view of the electromagnetic suction valve in the second embodiment of the present invention

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

The first embodiment of the present invention will be described below with reference to FIGS.
First, the configuration and operation of the system will be described with reference to the overall schematic diagram of FIG. FIG. 1 is a diagram schematically showing the overall configuration of the high-pressure fuel pump.
A portion surrounded by a broken line indicates a high-pressure pump main body, and the mechanism and components shown in the broken line indicate that the high-pressure pump main body 1 is integrated. The fuel in the fuel tank 20 is pumped up by the feed pump 21 and sent to the suction joint 10 a of the pump body 1 through the suction pipe 28. The fuel that has passed through the suction joint 10a reaches the suction port 30a of the electromagnetic suction valve mechanism 30 that constitutes the variable capacity mechanism via the pressure pulsation reducing mechanism 9 and the suction passage 10d.

The electromagnetic suction valve mechanism 30 includes an electromagnetic coil 30b. When the electromagnetic coil 30b is not energized, the movable element 30c moves to the right in FIG. 1 and the spring 33 is not compressed. A suction valve body 31 attached to the tip of the mover 30c opens a suction port 32 connected to the pressurizing chamber 11 of the high-pressure pump. Due to the biasing force of the spring 33, the suction valve body 31 is biased in the valve opening direction, and the suction port 32 is open.

Specifically, it operates as follows.
When the plunger 2 is displaced downward in FIG. 1 by the rotation of the cam 5 described later and is in the suction process state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. In this step, the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d (suction port 30a), and fuel flows from the suction port 30a through the suction port 32 into the pressurization chamber 11.

When the plunger 2 finishes the suction process and moves to the compression process (a state of moving upward in FIG. 1), the suction valve body 31 still remains open. The volume of the pressurizing chamber 11 decreases with the compression movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 passes through the suction valve body 31 that is opened again, and the suction passage 10 d (suction). Since the pressure is returned to the port 30a), the pressure in the pressurizing chamber does not increase. This process is called a return process. In this state, when a control signal from the engine control unit 27 (hereinafter referred to as ECU) is applied to the electromagnetic intake valve mechanism 30, an electric current flows through the electromagnetic coil 30b of the electromagnetic intake valve mechanism 30 and is movable by the magnetic attractive force. The child 30c moves to the left in FIG. 1, and the spring 33 is compressed. As a result, the suction valve body 31 also moves to the left in FIG. 1 and the suction port 32 is closed.

When the suction port 32 is closed, the fuel pressure in the pressurizing chamber 11 increases with the upward movement of the plunger 2 from this time. When the pressure exceeds the pressure of the fuel discharge port 12, high pressure discharge of the fuel remaining in the pressurizing chamber 11 is performed via the discharge valve mechanism 8 and supplied to the common rail 23. This process is called a discharge process. That is, the compression process of the plunger 2 (the ascending process from the lower start point to the upper start point) includes a return process and a discharge process. In this state, when the control signal from the ECU 27 is canceled and the electromagnetic coil 30b is de-energized, the magnetic attractive force acting on the mover 30c is after a certain time (after magnetic and mechanical delay time). Erased. Since the urging force of the spring 33 is acting on the mover 30c, it tries to move in the right direction in FIG. However, during the compression stroke of the plunger 2, the pressure in the pressurizing chamber 11 is high, and the suction valve body 31 is maintained in the closed state by the pressure. Therefore, even after the control signal from the ECU 27 is released, the mover 30c is maintained in the state of moving to the left in FIG. 1 during the compression stroke of the plunger 2.
When the compression stroke of the plunger 2 is completed and the suction stroke is started again, the pressure in the pressurizing chamber 11 decreases, the suction valve body 31 moves to the right in FIG. 1, and the suction port 32 is opened. Accordingly, the mover 30c also moves to the right in FIG.

By controlling the timing of starting energization of the electromagnetic coil 30b of the electromagnetic intake valve mechanism 30, the amount of high-pressure fuel discharged can be controlled. If the timing of starting energization to the electromagnetic coil 30b is advanced, the ratio of the return process in the compression process is small and the ratio of the discharge process is large. That is, the amount of fuel returned to the suction passage 10d (suction port 30a) is small, and the amount of fuel discharged at high pressure is large. On the other hand, if the timing of starting the input voltage is delayed, the ratio of the return process in the compression process is large and the ratio of the discharge process is small. That is, the amount of fuel returned to the suction passage 10d is large, and the amount of fuel discharged at high pressure is small. The timing at which the electromagnetic coil 30b is de-energized is controlled by a command from the ECU.
By configuring as described above, the amount of fuel discharged at high pressure can be controlled to the amount required by the internal combustion engine by controlling the timing at which the energization of the electromagnetic coil 30b is released.

A discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve seat 8a, a discharge valve 8b, and a discharge valve spring 8c. When there is no fuel differential pressure in the pressurizing chamber 11 and the fuel discharge port 12, the discharge valve 8b is biased by the discharge valve spring 8c. Is pressed against the discharge valve seat 8a and is in a closed state. Only when the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the fuel discharge port 12, the discharge valve 8 b opens against the discharge valve spring 8 c, and the fuel in the pressurization chamber 11 is discharged from the fuel discharge port. 12 is discharged to the common rail 23 through a high pressure.

Thus, the fuel guided to the fuel suction port 10 a is pressurized to a high pressure by the reciprocating motion of the plunger 2 in the pressurizing chamber 11 of the pump body 1, and is pumped from the fuel discharge port 12 to the common rail 23.

The common rail 23 is provided with an injector 24 and a pressure sensor 26. The injectors 24 are mounted in accordance with the number of cylinders of the internal combustion engine, and are opened and closed according to a control signal from an engine control unit (ECU) 27 to inject fuel into the cylinders.

The pump main body 1 is further provided with a relief passage 100A that communicates the downstream side of the discharge valve 8b and the pressurizing chamber 11, bypassing the discharge valve, separately from the discharge flow path. The relief passage 100A is provided with a relief valve 102 that restricts the flow of fuel in only one direction from the discharge passage to the pressurizing chamber 11. The relief valve 102 is pressed against the relief valve seat 101 by a relief spring 104 that generates a pressing force. When the pressure difference between the pressurizing chamber and the relief passage exceeds a specified pressure, the relief valve 102 is The valve is set to be opened away from the seat 101.

When an abnormally high pressure is generated in the common rail 23 or the like due to a failure of the injector 24 or the like, when the differential pressure between the relief passage 100A and the pressurizing chamber 11 becomes equal to or higher than the opening pressure of the relief valve 102, the relief valve 102 opens and the abnormally high pressure is generated. The fuel thus obtained is returned from the relief passage 100A to the pressurizing chamber 11, and the high-pressure section piping such as the common rail 23 is protected.

Hereinafter, the configuration and operation of the high-pressure fuel pump will be described in more detail with reference to FIG. FIG. 2 is a cross-sectional view seen from the front of the high-pressure fuel pump.

A pressurizing chamber 11 is formed at the center of the pump body, and an electromagnetic suction valve mechanism 30 for supplying fuel to the pressurizing chamber 11 and a discharge valve for discharging fuel from the pressurizing chamber 11 to the discharge passage. A mechanism is provided.

The cylinder 6 that guides the forward and backward movement of the plunger 2 is attached so as to face the pressurizing chamber 11. The outer periphery of the cylinder 6 is held by a cylinder holder 7 and is fixed to the pump body 1. The cylinder 6 holds the plunger 2 that moves forward and backward in the pressurizing chamber so as to be slidable along the forward and backward movement direction.

The lower end of the plunger 2 is provided with a tappet 3 that converts the rotational motion of the cam 5 attached to the camshaft of the engine into a vertical motion and transmits it to the plunger 2. Thereby, the plunger 2 can be moved back and forth (reciprocated) up and down with the rotational movement of the cam 5. The damper cover 14 is provided with a pressure pulsation reduction mechanism 9 that reduces the pressure pulsation generated in the pump from spreading to the fuel pipe 28.

The fuel that has passed through the pressure pulsation reducing mechanism 9 flows into the pressurizing chamber 11 through the suction port 32 in the order of the suction passage 10b and the suction port 30a. As described above, the electromagnetic suction valve mechanism 30 includes the electromagnetic coil 30b. When the electromagnetic coil 30b is not energized, the movable element 30c moves to the right in FIG. 1 and the spring 33 is not compressed. It is. A suction valve body 31 attached to the tip of the mover 30c opens a suction port 32 connected to the pressurizing chamber 11 of the high-pressure pump. Due to the biasing force of the spring 33, the suction valve body 31 is biased in the valve opening direction, and the suction port 32 is open.

When a control signal is applied to the electromagnetic suction valve mechanism 30 during the compression period of the plunger 2, a current flows through the electromagnetic coil 30b of the electromagnetic suction valve mechanism 30, and the mover 30c moves to the left in FIG. The spring 33 is compressed. At this time, the mover 30c moves until it collides with the stator 34, and an impact sound is generated when it collides with the stator 34. In general, it can be said that the faster the speed of the colliding object, the louder the collision sound, and the sound generated when the mover 30c collides with the stator 34 also reduces the moving speed of the mover 30. Sound can be reduced.

In order to slow down the moving speed of the mover 30c, it is conceivable to reduce the magnetic attractive force by the electromagnetic coil 30b. However, if the magnetic attractive force is reduced, it takes time for the mover to move, and the intake valve body 31 cannot open and close the intake valve within a predetermined response time. In order to reduce collision noise while maintaining a predetermined response time for the suction valve, it is desirable to decelerate immediately before the movable element 30c collides with the stator 34. Therefore, the present invention realizes that the movable element 30c is decelerated immediately before it collides with the stator 34 by using the force of the fluid.

Details of the first embodiment will be described below with reference to FIG. FIG. 3 is a detailed cross-sectional view of the movable element 30c, the stator 34, and the members that support the movable element 30c in the first embodiment.

In the first embodiment, the space filled with the fuel formed by the movable element 30c and the fixed member in the region indicated by the broken line in FIG. The volume of the cavity 301 changes before and after the mover 30c starts to move, and the changed volume of fuel enters and exits the cavity 301. A passage 302 connecting the cavity 301 and the suction port 30a is provided in the support member 306 so that the fuel can enter and exit the cavity 301. When the mover 30c is moved to the left in FIG. 3 by the magnetic attractive force as described above, the fuel is pushed out from the cavity 301. The pushed fuel flows through the passage 302 to the suction port 30a as shown by the arrow 303.

Here, the protrusion 304 is provided on the mover 30c so as to overlap the passage 302 when viewed from the moving direction of the mover. Thus, after the movable element 30c moves to the left in FIG. 3, the protrusion 304 covers and closes the exit of the passage 302. At this time, the flow path of the fuel flowing through the passage 302 becomes narrower when the projection 304 closes the outlet of the passage 302. That is, in the fuel flow path from the cavity 301 to the suction port 30a, the minimum flow path area is reduced by the movement of the mover 30c. At this time, the smallest flow path is an axial gap formed by the mover 30 c and the wall surface of the support member 306.

That is, the high-pressure fuel pump of this embodiment is provided with a pressurizing chamber 11 for pressurizing the fuel, and an electromagnetic that is provided on the suction side of the pressurizing chamber and opens and closes the fuel flow path (suction passage 10b) on the suction side. And an intake valve mechanism 30. Further, the electromagnetic suction valve mechanism 30 includes a movable portion (movable element 30c) that moves by a magnetic attractive force, and a cavity whose volume is increased or decreased by the movement of the movable portion (movable element 30c) on the outer peripheral side of the movable portion (movable element 30c). Part 301 is formed. A fuel flow path (passage 302) for supplying fuel from the cavity 301 to the pressurizing chamber 11 side is formed, and the area of the fuel discharged from the fuel flow path (passage 302) is magnetically attracted by the mover 30c. It is configured to decrease by moving by force. The movable portion (movable element 30c) is formed with a protrusion 304 that protrudes toward the outer peripheral side on the side of the pressurizing chamber 11 with respect to the fuel flow path (passage 302). The protrusion 304 is connected to the fuel flow path (passage 302). It is formed to overlap in the movable direction.
In the present embodiment, the fuel flow path (passage 302) is formed in the support member 306 provided on the outer peripheral side of the movable portion (movable element 30c) and closer to the pressurizing chamber 11 side than the cavity portion 301. The fuel flow path (passage 302) opens from both the end surface on the pressurizing chamber 11 side of the support member 306 to the end surface on the cavity portion 301 side, and penetrates the support member 306 in a substantially linear shape. Provided. Although a cross-sectional view is shown in FIG. 3, a plurality of support members 306 may be provided in the circumferential direction. Further, the protrusion 304 is formed in a substantially disk shape having a predetermined thickness, and is disposed corresponding to the support member 306. The flow path area of the fuel, that is, the gap between the support member 306 and the protrusion 304 in the moving direction of the mover 30c is reduced by the movement of the mover 30c by the magnetic attractive force, and the flow path area is reduced.

When the flow path area is reduced, that is, the flow path is narrowed, the fuel flowing through the passage 302 to the suction port 30a becomes difficult to flow. Since it becomes difficult for the fuel passing through the passage 302 to flow, the movement of the mover 30c is obstructed and the moving speed is reduced. Specifically, since the fuel flowing through the passage 302 becomes difficult to flow, the fuel in the cavity 301 is compressed by the mover 30c, and the pressure in the cavity 301 temporarily rises. As the pressure in the cavity 301 rises, the mover 30c receives the pressure and the moving speed becomes slow.

Also, immediately after the mover 30c starts moving, the distance between the projection 304 and the passage 302 is long, so the flow path is wide and the fuel flows relatively easily. On the other hand, since the flow path is narrowed immediately before the mover 30c collides with the stator 34, the fuel is more difficult to flow. As a result, the mover 30c can be greatly decelerated immediately before the mover 30c collides with the stator 34, and the effect of reducing the collision noise of the mover 30c can be obtained without impairing the response when the intake valve is closed. it can.

Further, when the mover 30c collides with the stator 34 and stops, the minimum flow passage area is set to a predetermined value larger than zero. That is, the protrusion 304 is configured so that a flow path for sending fuel from the fuel flow path (passage 302) to the pressurizing chamber 11 side is formed even when the movable element 30c collides with the stator 34. Specifically, when the movable element 30c shown in FIG. 3 collides with the stator 34, a part or all of the protrusions 304 of the movable element 30c do not come into contact with the passage 302. By making the distance between the protrusion 304 and the exit of the passage 302 larger than the moving distance of the mover 30c, when the mover 30c collides with the stator 34 and stops, the protrusion 304 and the exit of the passage 302 (opening) (A side end surface). That is, at the position corresponding to the passage 302, the protrusion 304 is formed so as to be recessed on the opposite side of the passage 302, so that the minimum flow passage area does not become zero even after the mover 30c stops. , Make fuel flow.

By doing so, it is possible to avoid completely blocking the flow path connecting the cavity 301 and the suction port 30a. If the passage 302 connecting the cavity 301 and the suction port 30a is completely blocked by the protrusion 304 provided on the movable element 30c, a large deceleration effect can be obtained when the movable element 30c moves to the left in FIG. However, when the mover 30c moves to the right in FIG. 3, it may take a long time to start moving.

This is due to the fact that fuel can no longer enter and leave the cavity 301, which greatly hinders the movement of the mover 30c. When the intake valve opens, if it takes time to move the mover 30c, it takes time to open the intake valve, and the response of the intake valve is delayed. When the mover 30c collides with the stator 34 and stops, the minimum flow area is set to a predetermined value larger than zero, so that even when the intake valve is opened, the cavity portion 301 can be opened. Fuel can enter and exit, and movement of the mover 30c is not hindered. As a result, it is possible to obtain an effect of reducing the collision sound of the mover 30c without impairing the response when the intake valve is opened.

Details of the second embodiment will be described below with reference to FIG. FIG. 4 is a detailed sectional view of the movable element 30c, the stator 34, and the members that support the movable element 30c in the second embodiment.

In the second embodiment, the space filled with the fuel formed by the movable element 30c and the fixed member in the region indicated by the broken line in FIG. As in the first embodiment, the volume of the cavity 301 changes before and after the mover 30c starts moving, and the changed volume of fuel enters and exits the cavity 301. A passage 302 connecting the cavity 301 and the suction port 30a is provided in the movable element 30c so that the fuel can enter and exit the cavity 301. When the mover 30c is moved to the left in FIG. 3 by the magnetic attractive force as described above, the fuel is pushed out from the cavity 301. The pushed fuel flows through the passage 302 to the suction port 30a as shown by the arrow 303. Here, an outlet to the suction port 30a of the passage 302 provided in the mover 30c is provided so as to be perpendicular to the moving direction of the mover 30c, and when the mover 30c moves to the left in FIG. The support member 306 and the outlet of the passage 302 overlap each other. At this time, the flow path of the fuel flowing through the passage 302 is narrowed by the support member 306 closing the outlet of the passage 302. That is, as in the first embodiment, in the fuel flow path from the cavity 301 to the suction port 30a, the minimum flow path area is reduced as the mover 30c moves.

Further, immediately after the mover 30c starts to move, the support member 306 and the outlet of the passage 302 do not overlap, so that the flow path is wide and the fuel flows relatively easily. On the other hand, since the flow path is narrowed immediately before the mover 30c collides with the stator 34, the fuel is more difficult to flow. As a result, the mover 30c can be greatly decelerated immediately before the mover 30c collides with the stator 34, and the effect of reducing the collision noise of the mover 30c can be obtained without impairing the response when the intake valve is closed. it can.

DESCRIPTION OF SYMBOLS 1 High pressure fuel pump main body 2 Plunger 3 Tappet 11 Pressurization chamber 12 Fuel discharge port 8 Discharge valve mechanism 23 Common rail 20 Fuel rank 21 Feed pump 28 Suction piping 10a Suction joint 9 Pressure pulsation reduction mechanism 10b Suction passage 30 Electromagnetic suction valve mechanism 102 Relief Valve 30a Suction port 30b Electromagnetic coil 33 Spring 30c Movable element 34 Stator 306 Support member 303 Communication path

Claims

A pressurizing chamber for pressurizing the fuel;
In a high-pressure fuel pump provided on the suction side of the pressurizing chamber and having an electromagnetic suction valve mechanism that opens and closes a fuel flow path,
The electromagnetic suction valve mechanism includes a movable portion that moves by a magnetic attraction force, and a cavity portion that increases or decreases in volume due to the movement of the movable portion is formed on the outer peripheral side of the movable portion, and from the cavity portion to the pressurizing chamber A fuel flow path for supplying fuel is formed on the side of the fuel flow path, and a flow path area of the fuel discharged from the fuel flow path is configured to be reduced by moving the movable portion by a magnetic attraction force. And high pressure fuel pump.
The high-pressure fuel pump according to claim 1,
The high-pressure fuel pump according to claim 1, wherein the movable portion is formed with a protruding portion that protrudes outward from the fuel flow path toward the pressurizing chamber.
The high-pressure fuel pump according to claim 2,
The high-pressure fuel pump according to claim 1, wherein the protrusion is formed to overlap the fuel flow path in a movable direction of the movable part.
The high-pressure fuel pump according to claim 1,
The high-pressure fuel pump, wherein the fuel flow path is formed on a support member provided on an outer peripheral side of the movable portion and on the pressurizing chamber side with respect to the cavity portion.
The high-pressure fuel pump according to claim 4,
The fuel flow path is open to both the end surface on the pressurizing chamber side of the support member and the end surface on the cavity side, and is provided so as to penetrate the support member in a substantially linear shape. High-pressure fuel pump characterized by
The high-pressure fuel pump according to claim 4,
The high-pressure fuel pump according to claim 1, wherein a gap between the support member and the protrusion in the movable direction of the movable part is reduced by moving the movable element by a magnetic attractive force.
The high-pressure fuel pump according to claim 1,
A high-pressure fuel pump characterized in that a flow path is formed in which fuel from the fuel flow path is sent to the pressurizing chamber side in a state where the movable portion collides with a stator.