JPH10299611A - Variable delivery high pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a chamber in the downstream of a valve from acting as an accumulator chamber to wrongly suck fuel, and thereby display good forced feed characteristics. SOLUTION: In a variable delivery high pressure pump for pressurizing low- pressure fluid in a pressure chamber to pump the fluid to a high-pressure passage, a check valve 4 is provided between the pressure chamber and a low- pressure passage 51, and a solenoid valve 6 for controlling the flow rate of low-pressure fluid sucked in the pressure chamber is arranged in the upstream of the solenoid valve. The space inside the solenoid valve 6 and a passage 74c in the downstream of the solenoid valve 6 are communicated each other through a connecting passage 76 in the solenoid valve 6. By composing components of the solenoid valve 6, which are positioned in the space inside the solenoid valve 6 to make contact with the fluid inflowing through the communicating passage 76, of materials which do not deform by the pressure of the inflowing fluid, the space inside the solenoid valve is prevented from acting as an accumulator chamber even when the fluid inflowing into the space inside the solenoid valve 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common rail type fuel injection device for injecting high pressure fuel stored in a common rail (accumulation pipe) into each cylinder of a diesel engine by an injector, for pumping high pressure fluid into the common rail. And a variable discharge high pressure pump.

[0002]

2. Description of the Related Art A common rail injection system is known as one of the systems for injecting fuel into a diesel engine. In the common rail injection system, a common pressure accumulation pipe (common rail) communicating with each cylinder is provided, and a variable discharge high pressure pump is used to supply high-pressure fuel at a required flow rate to thereby keep the fuel pressure in the pressure accumulation pipe constant. keeping. The high-pressure fuel in the pressure accumulating pipe is injected into each cylinder by an injector at a predetermined timing (for example, Japanese Patent Application Laid-Open No. 64-73166).

FIG. 12 shows an example of a variable discharge high pressure pump used for such a purpose.
Inside the plunger 9 driven by a cam (not shown)
2 is reciprocally fitted, and a pressure chamber 93 is formed by the inner wall surface of the cylinder 91 and the upper end surface of the plunger 92.
A solenoid valve 94 is mounted above the pressure chamber 93, and the solenoid valve 94 is connected to a low-pressure passage 95 formed therein.
And a valve body 96 for opening and closing between the pressure chamber 93 and the pressure chamber 93.

The valve body 96 is in the valve-opening position in a state shown in FIG. 1 in which the coil 97 is not energized. When the plunger 92 is lowered, fuel flows from the low-pressure supply pump (not shown) through the low-pressure passage 95 and the gap around the valve body 96. After that, it is introduced into the pressure chamber 93. When the coil 97 is energized, the valve body 96 is attracted upward, and its substantially conical tip sits on the seat portion 98 to close the valve. At the same time, the fuel in the pressure chamber 93 is pressurized by the rise of the plunger 92, and is sent to the pressure accumulating pipe from the passage 99 provided on the side wall of the pressure chamber 93.

When the plunger 92 is raised, a force in the valve closing direction acts on the valve body 96 due to the fuel pressure in the pressure chamber 93. Therefore, once the valve body 96 is closed, energization of the coil 97 is stopped. Even if it does not open. For this reason, in the variable discharge high-pressure pump having the above-described configuration, the flow rate sent to the pressure accumulation pipe is controlled by so-called pre-stroke control that controls the valve closing timing. That is, after the plunger 92 moves to the ascent stroke, the valve is not closed immediately, the valve is kept open until the fuel in the pressure chamber 93 reaches a predetermined amount, and excess fuel is released to the low-pressure passage 95 side. Thereafter, by closing the valve and starting pressurization, a required amount of pressurized fluid is pressure-fed to the accumulator pipe.

However, when the oil feed rate of the pump increases with an increase in the engine speed, there arises a problem that the valve 96 closes (self-closes) regardless of the valve closing signal. This is because when the plunger 92 is raised, the valve body 96 directly receives the dynamic pressure of the fuel in the pressure chamber 93 on the lower end surface.
This is due to, for example, receiving the force in the valve closing direction due to the throttle effect of the fuel flowing toward the low pressure passage 95 from the gap between the valve and the seat portion 98, and the flow rate control may not be performed properly.

As a countermeasure, it is conceivable to increase the operating stroke of the valve body 96 or to increase the return spring force of the valve body 96, but in any case, the valve closing response is reduced. In order to maintain the valve-closing response, it is necessary to increase the amount of power supplied to the coil or increase the size of the coil to increase the attraction force of the solenoid valve, which increases the power cost and manufacturing cost of the solenoid valve. There was a problem.

In the variable discharge high-pressure pump having the above-described structure, the flow passage to the pressure chamber 93 is opened and closed by the solenoid valve 94, and the valve body 96 is seated in response to a valve closing signal to close the flow passage. Since a certain period of time is required until this time, usually, the operation response time is calculated in advance to control the valve closing timing.
However, when the rotation speed of the engine increases and the oil supply rate of the pump increases, the opening / closing operation cannot be performed in time, and there is a possibility that sufficient control cannot be performed.

Accordingly, the present inventors have made it possible to easily and reliably control the flow rate of pressure-feeding to the pressure accumulating pipe even when the engine speed is increased and the oil supply rate of the pump is high. Variable discharge, which is provided separately with a valve body for opening and closing between the low pressure passage and the pressure chamber and a valve body for controlling the flow rate of the low pressure fuel sucked into the pressure chamber from the low pressure passage for the purpose of not increasing the pressure Proposed high-volume high-pressure pump (Japanese Patent Application No. Hei 8-
No. 195653).

Referring to FIG. 13, the variable discharge high pressure pump is provided with a check valve 4 provided between the pressure chamber and the low pressure passage and in the low pressure passage upstream of the check valve 4. And a solenoid valve 6 for controlling the flow rate of the low-pressure fuel supplied to the pressure chamber. The check valve 4 has a flow path 43 that penetrates the housing 42 in the left-right direction in the figure, and a valve body 44 that opens and closes the flow path 43. A conical seat surface 45 is provided in the middle of the flow path 43. It is formed. The valve body 44 is urged rightward by a spring 46 disposed in the spring stopper 41, and in the state shown in which the solenoid valve 6 is closed, the valve body 44 is seated on the seat surface 45 and closed. I have.

The solenoid valve 6 has a housing 61 containing a coil 62 and a valve body 71 for slidably holding a valve body 73. An annular flow path 74a is formed around the left end of the valve body 73, and the flow path 74a
4b communicates with the fuel reservoir 52 and the flow path 74
At c, it communicates with the flow path 43 of the check valve 4.

An armature 64 is press-fitted and fixed to the right end of the valve body 73, and the armature 64 faces the stator 65 at a constant interval. The coil 62 is wound around a coil bobbin 62 a made of resin on the outer periphery of the stator 65, and a spring 67 is provided in a spring chamber 66 provided inside the stator 65.
Is urged to the left of the figure. Also, the coil bobbin 62a
O-rings 62b and 62c are used to seal the space between the motor and the stator 65 and the space between the housing 61, respectively.

A substantially conical seat surface 75 is formed at the end of the flow passage 74c. In the state shown in the drawing where the coil 62 is not energized, the distal end of the valve body 73 is seated on the seat surface 75. The space between the flow paths 74a and 74c is closed. When the coil 62 is energized, the armature 64 is attracted and the valve body 73
Is separated from the sheet surface 75 to open the space between the flow paths 74a and 74c. When the low-pressure fuel flows from the low-pressure passage 51 through the fuel reservoir 52 and the flow paths 74b, 74a, and 74c into the flow path 43 in the check valve 4 with the opening of the solenoid valve 6, the valve body is pressed by the fuel pressure. The valve 44 is opened, and fuel is supplied to a pressure chamber (not shown). When the solenoid valve 6 closes, the flow of low-pressure fuel into the flow path 43 stops, and the valve body 44 closes.

As described above, when the required flow rate is supplied into the pressure chamber by the solenoid valve 4 in advance, the check valve 4 closes the flow path to the pressure chamber from the start of pressurization of the low-pressure fuel to the end of the pressure feed. The feed pressure (about 15
Pressure). Therefore, there is no need to increase the size of the solenoid valve 6, and the cost can be reduced.

[0015]

Here, the solenoid valve 6
When the valve is opened, the valve 73 is moved so that the fuel in the spring chamber 66 can move when the armature 64 moves to the right.
Of the spring chamber 6 through the communication passages 76 and 76 'provided therein.
6 and the flow path 74c downstream of the valve body 73 are communicated. Therefore, in the above configuration, even when the valve body 73 is closed, the space inside the solenoid valve 6 and the flow path 74c downstream of the valve body 73 via the communication passages 76 and 76 ', that is, the armature The passage 64a in the 64, the armature 64
The surrounding armature chamber 64b and the spring chamber 66 communicate with each other.

However, at this time, the coil bobbin 62a made of resin is provided in the space inside the electromagnetic valve 6 into which the fuel flows.
Also, since members made of an elastic material such as the O-rings 62b and 62c are provided, the deformation caused by the feed pressure causes the valve body 73 and the valve body 44 of the check valve 4 to move.
There is a problem that a volume or more of fuel is stored in a space surrounded by a circle (hereinafter referred to as a valve downstream chamber). In other words, the coil bobbin 62a and the O-rings 62b and 62c act as a diaphragm, and the valve downstream chamber functions as an accumulator chamber, and while the solenoid valve 6 is open, the communication path 76, 76 ' Fuel is temporarily stored in the space inside the solenoid valve 6. This fuel may be improperly sucked in after the solenoid valve 6 is closed, thereby deteriorating the pumping characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable discharge high pressure pump which prevents a fuel from being illegally sucked by a valve downstream chamber acting as an accumulator chamber and which exhibits good pumping characteristics. is there.

[0018]

According to a first aspect of the present invention, there is provided a variable discharge high pressure pump comprising: a plunger inserted reciprocally in a cylinder; an inner wall surface of the cylinder and an end face of the plunger; And a means for pressurizing the low-pressure fluid introduced from the low-pressure passage by the reciprocating motion of the plunger, and a means for pressure-feeding the pressurized fluid to the high-pressure passage. Between the pressure chamber and the low pressure passage,
When the low-pressure fluid is sucked into the pressure chamber, the pressure chamber and the low-pressure passage are opened, and the pressure chamber and the low-pressure fluid sucked into the pressure chamber are pressurized from the start of pressurization to the end of pressurization of the pressurized fluid. A valve member for closing between the low-pressure passages is provided, and an electromagnetic valve is disposed in the low-pressure passage upstream of the valve member.
The flow rate of the low-pressure fluid sucked into the pressure chamber via the valve member is controlled. The space inside the solenoid valve and the low-pressure passage downstream of the solenoid valve communicate with each other through a communication passage formed in the solenoid valve, and a fluid located in the space inside the solenoid valve and flowing through the communication passage. The constituent members of the solenoid valve that come into contact with are made of a material that is not deformed by the flowing fluid pressure.

According to the above configuration, there is no member deformable by fluid pressure, that is, a member acting as a diaphragm, in the space inside the electromagnetic valve. Even if the fluid flows into the space inside the valve, the fluid does not accumulate. Therefore, the valve downstream chamber does not act as an accumulator chamber, and the fluid is not improperly sucked into the pressure chamber after the solenoid valve is closed, so that the pumping characteristics are improved.

According to a second aspect of the present invention, the solenoid valve includes a valve for opening and closing the low pressure passage, and a coil for driving the valve. The coil is wound around a coil bobbin made of resin, and a space for accommodating the coil and the coil bobbin and a space inside the solenoid valve are provided with a partition made of an inelastic and non-magnetic material, It blocks both spaces.

According to the above construction, the space for accommodating the coil bobbin made of resin, which is likely to be deformed by the fluid pressure, and the space inside the solenoid valve into which the fluid flows are partitioned by the partition wall. No fluid pressure acts on the Therefore, the coil bobbin does not act as a diaphragm, and good pumping characteristics can be obtained.

According to the third aspect of the invention, the communication passage is provided inside the valve body. This is advantageous when there is not enough space.

According to a fourth aspect of the present invention, the variable discharge high pressure pump is formed by a plunger fitted reciprocally in the cylinder, an inner wall surface of the cylinder and an end face of the plunger, and is introduced from the low pressure passage. A pressure chamber for pressurizing the low-pressure fluid by the reciprocating motion of the plunger, means for feeding the pressurized fluid to the high-pressure passage, and a pressure chamber provided between the pressure chamber and the low-pressure passage, for supplying the low-pressure fluid to the pressure chamber. Opening between the pressure chamber and the low-pressure passage at the time of suction, and closing between the pressure chamber and the low-pressure passage from the start of pressurization of the low-pressure fluid sucked into the pressure chamber to the end of the pressurized fluid supply. A valve member, and an electromagnetic valve disposed in the low-pressure passage upstream of the valve member, for controlling a flow rate of a low-pressure fluid sucked into the pressure chamber through the valve member. The solenoid valve includes a valve body that opens and closes the low-pressure passage, and a coil that drives the valve body. The low-pressure passage upstream of the solenoid valve and the low-pressure passage downstream of the solenoid valve are connected to each other by the electromagnetic valve. And the low-pressure passage downstream of the solenoid valve when the valve body of the solenoid valve is closed,
The space inside the solenoid valve communicating with the communication passage inside the valve body of the solenoid valve is shut off.

In the above structure, when the valve element is opened, the fluid flows from the low pressure passage upstream of the solenoid valve to the low pressure passage downstream of the solenoid valve through the space inside the solenoid valve and the communication passage. Inflow. When the valve body is closed, the space between the inside of the solenoid valve and the low-pressure passage downstream of the solenoid valve is shut off, so that fuel is supplied from the space inside the solenoid valve downstream from the valve body. Never. Therefore, the space between the valve element and the valve member does not act as an accumulator chamber, and the pumping characteristics are not reduced. Further, since the space inside the solenoid valve is always in communication with the low-pressure passage upstream of the solenoid valve, the movement of fuel inside the solenoid valve is not restricted.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example in which the variable discharge high pressure pump of the present invention is applied to a common rail injection system of a diesel engine will be described. In the system diagram of FIG. 2, the engine E is provided with a plurality of injectors I corresponding to the combustion chambers of each cylinder, and these injectors I are connected to a common high-pressure accumulator pipe, a so-called common rail R, for each cylinder. The injection of fuel from the injector I into each combustion chamber of the engine E is performed by the ON-OF of the injection control solenoid valve B1.
The fuel in the common rail R is controlled by the injector I by the engine E while the solenoid valve B1 is open.
Injected to. Therefore, it is necessary to continuously accumulate a fuel having a high predetermined pressure corresponding to the fuel injection pressure in the common rail R. Therefore, the variable discharge of the present invention is performed through the supply pipe R1, which is a high pressure passage, and the discharge valve B2. The quantity high pressure pump P is connected.

The variable discharge high pressure pump P pressurizes low pressure fuel sucked from the fuel tank T via the feed pump P1 to high pressure, and controls the fuel in the common rail R to high pressure. The common rail R is provided with a pressure sensor S1 for detecting a common rail pressure, and an electronic control unit ECU for controlling the system transmits a signal from the pressure sensor S1 to an optimum value set in advance in accordance with a load and a rotation speed. The discharge amount of the variable discharge amount high pressure pump P is controlled so that Further, the electronic control unit ECU receives, for example, an engine speed sensor S2 and a load sensor S3.
The number of rotations and load information are input and the electronic control unit EC
U determines the optimal injection timing and injection amount (injection period) according to the engine state determined by these signals, and outputs a control signal to the injection amount control solenoid valve B1.

Next, the details of the variable discharge amount high pressure pump P will be described with reference to FIG. In the figure, a drive shaft D that is rotationally driven by an engine E (see FIG. 2) in synchronization with a half rotation of the engine is inserted and held in a pump housing 1. Vane type feed pump P1 for fuel supply
Are connected. The feed pump P1 rotates integrally with the drive shaft D, draws fuel from the fuel tank T (see FIG. 2), and pressurizes the fuel pressurized to a low pressure through the passages 11, 12,.
The fuel is supplied to the fuel pool 52 through the ports 13 and 51. The fuel discharge side and the fuel suction side of the feed pump P1 are connected via a pressure adjusting valve (not shown) so that the discharge pressure can be adjusted. As described above, in the present embodiment, the variable discharge amount high pressure pump P has a configuration in which the feed pump P1 shown in FIG. 2 is built.

The feed fuel from the feed pump P1 is supplied to the entire inside of the pump via the throttle S, and is also used as a lubricant. The fuel used as a lubricant is led out from a regulating valve V for controlling the pressure inside the pump (generally, approximately atmospheric pressure) and returned to the fuel tank T.

The drive shaft D has a bearing D
1, and D2, it is rotatably supported by the pump housing 1, and at the right end thereof, an inner cam 8 described later in detail is integrally formed. In the present embodiment, the drive shaft D and the inner cam 8 are integrated, but they may be separated and connected by a joint.

A head 14 is fitted in the right end opening of the pump housing 1, and the head 14 is inserted into the inner cam 8 with its left end center protruding. A plurality of plungers 21 are reciprocally and slidably supported in a sliding hole 2 provided at the center of the left end of the head 14, and the inner end face of each plunger 21 and the sliding hole 2 A pressure chamber 23 is formed between the pressure chamber 23 and the inner wall. Pressure chamber 23
Is connected to the fuel reservoir 52 via the passage 15, the check valve 4, and the electromagnetic valve 6, and functions as a pressurizing chamber for pressurizing the fuel into which the low-pressure fuel flows from the fuel reservoir 52.

FIG. 3 is a view of the inner cam 8 as viewed from the front. The plurality of plungers 21 are arranged at equal intervals inside the ring-shaped inner cam 8. A shoe 24 is provided at an outer end of each plunger 21, and a cam roller 22 is rotatably held on each shoe 24. The inner cam 8 is disposed so as to be in sliding contact with the outer periphery of the cam roller 22. On the inner peripheral surface of the inner cam 8, a cam surface 81 having a plurality of cam ridges arranged at equal intervals is formed. It is. Then, drive shaft D
When the inner cam 8 integrated with the cylinder 2 rotates, the plunger 21 reciprocates in the cylinder 2 and pressurizes the fuel in the pressure chamber 23 by raising the plunger 21. FIG. 3 shows a state where the plunger 21 is at the highest point.

The inner peripheral surface of the inner cam 8 is, as shown in FIG.
The top portion 82 of the cam ridge of the inner cam 8 is formed in an arc shape centering on the cam center O so that the plunger 21 maintains the state of FIG.
At this time, the lift curve of the inner cam 8 is flat (straight) at the top of the lift, and the lift of the plunger 21 driven by the inner cam 8 is the same. Therefore, the plunger 21 does not immediately start descending after reaching the maximum lift position, and holds this state while the inner cam 8 rotates by the angle ψ. While the plunger 21 is at the maximum lift position, fuel is not sucked in. Therefore, by controlling the opening of the solenoid valve 6 to be completed during this time, the valve body 63 of the solenoid valve 6 can be fully lifted. And the flow rate can be easily controlled. This angle ψ is
Normally 5 ° ~
It is appropriately selected within a range of 20 °.

In the conventional variable discharge high pressure pump,
In many cases, a spring that constantly presses the plunger 21 against the cam 8 is provided. However, the variable discharge high-pressure pump of the present invention employs a suction amount control method, and when the plunger 21 descends to the lowest point when the suction amount is small, Cavitation may occur due to decompression of the pressure chamber 23. Therefore, in the present invention, no spring is provided, and the reciprocating movement of the plunger 21 is performed by a cam lift by rotation of the drive shaft D at the time of pressure feeding, and by the pressure (feed pressure) of low-pressure fuel at the time of suction. Therefore, when the intake amount is small, the plunger 21 moves only by the amount of the supply of the low-pressure fuel, and the cam roller 22 and the inner cam 8 are separated.

The fuel pressurized in the pressure chamber 23 (FIG. 1)
It is supplied to the common rail R through a delivery valve 3 (corresponding to a discharge valve B2 in FIG. 2) and a supply pipe R1 from a discharge hole 16 provided in a wall of the pump housing 1 (see FIG. 2). The supply pressure varies depending on the operation state of the engine E, and is about 200 to 1500 atm. The delivery valve 3 has a function as a check valve, and has a valve body 31.
And a return spring 32 for urging the valve in the valve closing direction. The valve is opened when the pressurized fuel exceeds a predetermined pressure.

In FIG. 1, a lock adapter 5 in which the fuel reservoir 52 is formed is fixed to the right end face of the head 14. The fuel reservoir 52 is filled with low-pressure fuel pressurized to about 15 atm by the feed pump P1, and the low-pressure fuel flows into the pressure chamber 23 through the lock adapter 5 and a passage provided in the head 14. . In the middle of the flow path from the fuel reservoir 52 to the pressure chamber 23, a check valve 4 which is a valve member sandwiched between the lock adapter 5 and the head 14 is disposed. Is made to flow. At the right end of the lock adapter 5, an electromagnetic valve 6 for controlling the amount of low-pressure fuel flowing into the pressure chamber 23 is provided.
The solenoid valve 6 includes a flange 6 provided on the outer periphery of the housing 61.
3 is fixed by inserting a bolt. The solenoid valve 6 and the check valve 4 constitute the discharge control device P2 in FIG.

As shown in FIG. 4, the check valve 4 has a flow path 43 penetrating the housing 42 in the left-right direction, and a valve body 44 for opening and closing the flow path 43. The flow path 43 expands in the direction of the pressure chamber 23 (leftward in the figure) on the way to form a conical seat surface 45, and the valve body 44 is moved rightward by a spring 46 held in a spring stopper 41. Biased toward
It is seated on the seat surface 45. As described above, the check valve 4 is closed in the illustrated normal state, and when the solenoid valve 6 is opened and low-pressure fuel flows from the fuel reservoir 52, the valve body 44 is opened by the fuel pressure. It is done.

The solenoid valve 6 has a housing 61 containing a coil 62 and a valve body 71 fitted and fixed in the left end thereof. A valve body 73 is slid in a cylinder 72 provided in the valve body 71. It is movably held. Valve element 7
An annular flow path 74a is formed around the left end of the fuel cell 3, and the flow path 74a communicates with the fuel reservoir 52 through a flow path 74b and the flow path 43c of the check valve 4 through a flow path 74c. Communicating.

A substantially conical seat surface 75 is formed at the open end of the flow path 74c. In the state shown in the drawing where the coil 62 is not energized, the distal end of the valve body 73 is seated on the seat surface 75. The space between the flow paths 74a and 74c is closed. When the coil 62 is energized, the armature 64 is attracted, the distal end of the valve body 73 integrated therewith separates from the seat surface 75, and opens between the flow paths 74a and 74c. As described above, the electromagnetic valve 6 is configured to be closed in a non-energized state, so that there is an effect of preventing the fuel from being pumped when the coil is damaged.

An armature 64 is press-fitted and fixed to the right end of the valve body 73, and the armature 64 faces the stator 65 at a constant interval. A coil 62 wound around a coil bobbin 62a is arranged outside the stator 65,
A spring 67 is provided in a spring chamber 66 provided inside the stator 65, and urges the armature 64 to the left in the drawing. The communication passages 76 and 7 are provided in the valve body 73.
6 ′ is formed, and the space in the housing 61 communicates with the flow path 74 c downstream of the valve body 73 via the communication passages 76 and 76 ′.

Here, on the outer periphery of the stator 65, a cylindrical member 6 serving as a partition wall made of a non-magnetic material and not deformed by the feed pressure, for example, a metal material such as aluminum.
8 are press-fitted, and both ends thereof are in close contact with the left and right inner side walls of the housing 61. The cylindrical member 68 is provided in the housing 61 so that the space on the outer peripheral side in which the coil bobbin 62a and the coil 62 are accommodated, the communication passage 76,
It functions as a partition for partitioning into the space on the inner peripheral side communicating with 76 ′, so that feed pressure is not applied to the coil bobbin 62a made of resin. Further, the cylindrical member 68 also serves as a sealing material for surface sealing between the housing 61 and the stator 65.

Next, the operation of the variable discharge high pressure pump having the above configuration will be described with reference to FIGS. In FIG. 6, the NE pulse is a waveform obtained by shaping the output signal from the engine speed sensor S2 in FIG. 2 in the electronic control unit ECU. The electronic control unit ECU controls the energization of the coil 62 of the solenoid valve 6 based on the NE pulse and signals from the load sensor S3, the pressure sensor S1, and a water temperature sensor and an atmospheric pressure sensor (not shown).

At a point (a) in FIG. 6, the coil 62 of the solenoid valve 6 in FIG. 1 is not energized, the valve body 73 is closed by the urging force of the spring 67, and the fuel pool 5 is closed.
2 and the passage 74c downstream of the valve body 73 are shut off. The valve body 44 of the check valve 4 is closed by the urging force of the spring 46. In the state of FIG. 6A, the cam roller 22 and the inner cam 8 are separated.

In the pressure feeding step, the lift of the inner cam 8 is started. Even if the inner cam 8 starts lifting, the plunger 21 does not immediately start rising, and when the lift amount of the inner cam 8 becomes equal to the lift amount of the plunger 21 (FIG. 6B), the cam roller 22 turns the inner cam. 8, the cam roller 22 pushes up the plunger 21 via the shoe 24. In this pumping step, the check valve 4
, The pressure of the pressurized fuel is applied, so that the valve body 44 does not open. Thereafter, the volume in the pressure chamber 23 decreases with the rise of the plunger 21, and the pressure in the pressure chamber 23 gradually increases. When the pressure of the fuel in the pressure chamber 23 exceeds a predetermined pressure, the supply pipe R passes through the passage 16 and the delivery valve 3.
1 supplies high-pressure fuel to the common rail R (FIG. 2). When the lift of the plunger 21 is maximized (FIG. 6)
(C)), the pressure feeding ends.

After the end of the pressure feeding, the suction process is started. The inner cam 8 forms the top portion 82 of the cam peak in an arc shape (FIG. 5), and the lift curve of the inner cam 8 is changed to the shape shown in FIG.
It is made flat between (c) and FIG. 6 (d). Therefore, the inner cam 8 does not immediately enter the suction step, and is maintained at the maximum lift. The maximum lift section (flat portion) is provided at a rotation angle of the inner cam 8 of 10 ° here, and during this time, the plunger 21 also maintains the maximum lift position.

The electronic control unit ECU controls the energization of the coil 62 so that the solenoid valve 6 starts to open and is fully opened during this 10 °. Since the solenoid valve 6 requires a certain time from the energization to the start of valve opening or from the energization to the completion of valve opening, it is difficult to control the fuel supply amount with the conventional configuration that immediately starts the suction process after the end of the pressure feeding process. On the other hand, a certain interval is provided from the end of the pressure feeding process to the start of the suction process,
By performing the valve opening operation of the solenoid valve 6 during this time, the solenoid valve 6 does not start to open before the end of the pressure feeding stroke, and does not start the valve closing operation before the full lift, so that the valve body 73 can be opened. Operation stabilizes.

After the point shown in FIG.
Since the valve body 73 of the solenoid valve 6 is open, the fuel pool 5
The low-pressure fuel flowing into the passage 47c from the
The valve body 44 of the check valve 4 is opened against the 6 forces and the pressure chamber 23 is opened.
Flows into. At this time, the plunger 21 is pushed down by the inflowing fuel, and the fuel is sucked until the solenoid valve 6 is closed.

When the energization of the coil 62 from the electronic control unit ECU is interrupted, the valve body 73 of the solenoid valve 6 closes (FIG. 6 (e)), and the space between the fuel reservoir 52 and the passage 47c, ie, the pressure chamber 23. When the fuel stops flowing, the valve body 44 of the check valve 4 is also closed by the urging force of the spring 46. After that, the inner cam 8 continues to descend, but when the suction ends, the lift of the plunger 21 stops, and the cam roller 22 and the inner cam 8 separate.

Here, the amount of fuel supplied from the fuel reservoir 52 to the pressure chamber 23 is controlled by the time of energizing the coil 62 of the solenoid valve 6. The dotted line in FIG. 6 indicates that the supply amount is large, the plunger 21 descends to the lowest point, and the maximum amount of fuel is sucked into the pressure chamber 23. Valve body 73 of solenoid valve 6
When the valve closing timing is advanced, the lowering of the plunger 21 stops halfway as shown by the solid line in FIG. 6, and the fuel flowing into the pressure chamber 23 decreases.

FIG. 7 shows the cam speed of the inner cam 8 in one cycle from the start of the pressure feeding process to the end of the suction stroke. The cam speed is zero during 10 ° from the end of the pressure feeding process to the start of the suction stroke. Becomes During this time, the cam lift in FIG. 6 is flat. In addition, since the inner cam 8 is substantially circular, in order to obtain such a lift curve, this 10 ° section is formed into an arc shape centered on the point O,
It is necessary to keep the distance from the center O constant (see FIG. 5).

FIG. 8A shows the pumping characteristics of the variable discharge high pressure pump of the present invention. In the figure, the valve opening angle θ represents a period between the time when the lift curve of the inner cam 8 shown in FIG. 6 is (c) and (e), that is, a period from when the pumping is completed to when the solenoid valve 6 is closed. This is represented by the rotation angle of the inner cam 8. In the present invention, the flow path 74c downstream of the valve body 73
Inside the solenoid valve 6 communicating with the coil bobbin 62a
Is closed by a partition made of a cylindrical member 68 so that the resin coil bobbin 62a does not receive the feed pressure. Further, since the cylindrical member 68 also serves as a sealing material, there is no member acting as a diaphragm in the space inside the solenoid valve 6, and the valve body 73 and the valve body 44 are not provided.
The valve downstream chamber formed between them does not act as an accumulator chamber.

Therefore, in FIG.
When the valve is opened at an angle equal to or less than 0 °, the valve body 73 opens only when the lift of the inner cam 8 is flat (the period from FIG. 6C to FIG. 6D). Since it does not act as an accumulator chamber, fuel is not temporarily stored there, and the suction amount (pumping amount) becomes zero. When the valve opening angle θ is 10 ° or more, the pumping amount increases linearly with an increase in the angle θ, so that the pumping amount can be easily controlled by adjusting the angle θ.

On the other hand, in the conventional configuration shown in FIG. 13, the pumping characteristics are as shown in FIG. 8B, and the pumping characteristics deteriorate in a small angle region where the valve opening angle θ is 10 ° or less. .
In this region, for example, at point P in the figure, since the valve body 73 is opened only when the lift of the inner cam 8 is flat, fuel is theoretically not taken in and the pumping amount should be zero. There was, but it was not actually zero. This is because the opening of the solenoid valve 6 causes the communication path 7 in the valve body 73 to open.
The fuel is introduced into the space inside the electromagnetic valve 6 through the valves 6 and 76 ', and is temporarily stored in the valve downstream chamber by the deformation of the coil bobbin 62a and the O-rings 62b and 62c. Thereafter, in the suction stroke of the cam lift, the pressure is sucked into the pressure chamber 23 which has become equal to or lower than the feed pressure, and the pressure feeding characteristics are deteriorated.

As described above, according to the above configuration, since a member such as resin which is deformed by the feed pressure is not arranged in the space inside the electromagnetic valve 6 into which the fuel flows, the fuel is accumulated in the space inside the electromagnetic valve 6. Never. In addition, the cylindrical member 68 serving as a partition also serves as a sealing material, and the O-ring provided between the housing 61 and the conventional structure can be omitted, so that the number of parts does not increase. Therefore, good pumping characteristics can be realized with a simple configuration.

FIGS. 9 and 10 show a second embodiment of the present invention. In the present embodiment, the fuel supply path is different from the configuration of the first embodiment, and a communication path 61a communicating with the fuel reservoir 52 is provided on the outer peripheral wall of the housing 61 of the solenoid valve 6 (see FIG. 9 (a)), a communication hole 73a is provided in the side wall of the valve body 73 (FIG. 9 (b)), and the flow path 5
1. The fuel is introduced from the fuel reservoir 52 into the communication passage 76 in the valve body 73 through the communication passage 61a and the communication hole 73a. The valve body 71 forming the seat surface 75 of the valve body 73 closes the left end surface, and has an outer diameter smaller than the flow path 74c downstream of the valve body 73. When the valve body 73 is opened, As shown by the arrow in FIG. 10, fuel is introduced from the communication path 76 of the valve element 73 to the flow path 74c downstream of the valve element 73 via the seat surface 75 and the flow paths 74a and 74b. With the pressure of this fuel, the valve body 44 of the check valve 4
When the valve is opened, the fuel flows into the pressure chamber (not shown).

According to the above configuration, as shown in FIG.
When the solenoid valve 6 is closed, the flow path 74c downstream of the valve body 73 and the communication path 76 formed in the valve body 73 are shut off. That is, since the valve downstream chamber and the space inside the electromagnetic valve 6 communicating with the communication passage 76 are shut off, fuel does not flow into the flow passage 74c after the valve is closed. Therefore, the valve downstream chamber does not act as an accumulator chamber,
The pumping characteristics do not deteriorate. Therefore, it is not necessary to provide the cylindrical member 68 in the first embodiment, and a portion other than the portion relating to the feed path has a normal solenoid valve configuration.
For example, it is possible to adopt a configuration in which a member that is likely to be deformed by receiving a feed pressure is accommodated in a space inside the electromagnetic valve 6. Further, since the space inside the solenoid valve 6 is always in communication with the flow path 51 which is a low-pressure passage upstream of the solenoid valve 6 by the communication passage 61 a, the spring chamber 6 associated with the lift of the valve body 73.
The movement of the fuel in 6 is also performed without any trouble.

FIG. 11 shows a third embodiment of the present invention. In the present embodiment, an annular flow path 71a is provided around the right end of the valve body 73, and an annular flow path 71b is provided around a small-diameter intermediate portion of the valve body 73, and a space between these flow paths 71a, 71b is provided. A seat surface 75 is provided on the inner peripheral wall of the valve body 71, and a tapered surface 73b provided on the outer periphery of the valve body 73 is seated on the seat surface 75 to close the valve (FIG. 1).
1 (a)). The flow path 71b communicates with a cylindrical flow path 71c formed in the left half of the valve body 71,
1c communicates with a flow path 74c downstream of the solenoid valve 6. The flow passage 71 a communicates with the communication passage 61 a on the outer peripheral wall of the housing 61 and the fuel reservoir 52 via a passage in the shim 69 interposed between the valve body 71 and the housing 61. The left end face of the valve body 71 is closed, and when the valve body 73 is closed, the space between the solenoid valve 6 and the flow path 74c is shut off.

In the above configuration, the valve element 73 moves to the right (FIG. 11B), and the flow path 71a and the flow path 71b
When the space is opened, fuel is introduced into the flow path 74c downstream of the solenoid valve 6 via the flow path 51, the fuel reservoir 52, the communication path 61a, and the flow paths 71a, 71b, 71c. At this time, the shim 69 is formed in an inverted C-shape as shown in FIG. 11C, so that fuel is supplied through the notch 69a even when the valve body 73 is fully lifted. Also in the configuration of the present embodiment, when the valve body 73 is closed, the electromagnetic valve 6
Since the space between the internal space and the flow path 74c is shut off, the valve downstream chamber does not act as an accumulator chamber, and good pumping characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a variable discharge high pressure pump showing a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a fuel injection device including a variable discharge amount high-pressure pump according to the first embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a partially enlarged sectional view of FIG. 1;

FIG. 5 is a partially enlarged sectional view of FIG. 3;

FIG. 6 is a view for explaining the operation of the variable discharge high pressure pump according to the first embodiment.

FIG. 7 is a diagram illustrating a relationship between a cam speed and a cam lift in the first embodiment.

FIG. 8 is a diagram showing the pressure-feeding characteristics of a variable discharge amount high-pressure pump.

FIG. 9 is an overall sectional view of a variable discharge high-pressure pump according to a second embodiment of the present invention, in which (a) shows a state when the valve is closed, and (b) is a partially enlarged section of (a). FIG.

FIG. 10 is an overall cross-sectional view of the variable discharge high-pressure pump according to the second embodiment, showing a state when the valve is opened.

FIG. 11 is an overall cross-sectional view of a variable discharge high-pressure pump according to a third embodiment of the present invention, in which (a) illustrates a state when the valve is closed, and (b) illustrates a state when the valve is opened. Figure, (c) is (b)
FIG. 7 is a sectional view taken along line BB of FIG.

FIG. 12 is an overall sectional view of a conventional variable discharge high pressure pump.

FIG. 13 is a partially enlarged sectional view of a conventional variable discharge amount high pressure pump.

[Explanation of symbols]

 P Variable discharge amount high pressure pump R Common rail R1 Common piping (high pressure passage) 1 Pump housing 11, 12, 13 Passage (low pressure passage) 2 Cylinder 21 Plunger 22 Cam roller 23 Pressure chamber 3 Delivery valve (Pressure sending means) 31 Valve 32 Return spring 4 Check Valve (Valve Member) 42 Housing 43 Flow Path 44 Valve Element 46 Spring 5 Lock Adapter 51 Passage (Low Pressure Passage) 52 Fuel Pool 6 Solenoid Valve 62 Coil 66 Spring Chamber 67 Spring 68 Cylindrical Member (Partition) 71 Valve Body 73 Valve elements 74a, 74b Flow path 74c Flow path 76 Communication path 8 Inner cam 81 Cam surface 82 Top top

Claims (4)

[Claims] 1. A low-pressure fluid formed by an inner wall surface of the cylinder and an end face of the plunger, the low-pressure fluid being introduced from a low-pressure passage is added by the reciprocating motion of the plunger. A pressure chamber for pressurizing, means for pressure-feeding the pressurized fluid to the high-pressure passage, and a pressure chamber provided between the pressure chamber and the low-pressure passage; and a space between the pressure chamber and the low-pressure passage when the low-pressure fluid is sucked into the pressure chamber. Open up,
A valve member for closing the space between the pressure chamber and the low-pressure passage from the start of pressurization of the low-pressure fluid sucked into the pressure chamber to the end of the pressurization of the pressurized fluid; and a valve member upstream of the valve member in the low-pressure passage. An electromagnetic valve arranged to control a flow rate of a low-pressure fluid sucked into the pressure chamber through the valve member. A space inside the electromagnetic valve communicates with the low-pressure passage downstream of the electromagnetic valve by a communication passage. In the variable discharge high pressure pump, the constituent members of the electromagnetic valve which are located in the space inside the electromagnetic valve and come into contact with the fluid flowing through the communication passage are made of a material which is not deformed by the flowing fluid pressure. Features a variable discharge high pressure pump. 2. A space for accommodating the coil and the coil bobbin, wherein the solenoid valve includes a valve element for opening and closing the low-pressure passage, a coil for driving the valve element, and a coil bobbin made of resin for holding the coil. 2. The variable discharge high pressure pump according to claim 1, wherein a partition made of an inelastic and nonmagnetic material is provided between the space and the space inside the solenoid valve. 3. The variable discharge high pressure pump according to claim 2, wherein said communication passage is provided inside said valve body. 4. A low-pressure fluid formed by an inner wall surface of the cylinder and an end surface of the plunger, the low-pressure fluid being introduced from a low-pressure passage, being added by a reciprocating motion of the plunger. A pressure chamber for pressurizing, means for pressure-feeding the pressurized fluid to the high-pressure passage, and a pressure chamber provided between the pressure chamber and the low-pressure passage; and a space between the pressure chamber and the low-pressure passage when the low-pressure fluid is sucked into the pressure chamber. Open up,
A valve member for closing the space between the pressure chamber and the low-pressure passage from the start of pressurization of the low-pressure fluid sucked into the pressure chamber to the end of the pressurization of the pressurized fluid; and a valve member upstream of the valve member in the low-pressure passage. A variable discharge high pressure pump provided with a solenoid valve for controlling a flow rate of a low pressure fluid sucked into the pressure chamber through the valve member, wherein the solenoid valve opens and closes the low pressure passage; and A coil that drives a valve body, and connects the low-pressure passage upstream of the solenoid valve and the low-pressure passage downstream of the solenoid valve via a communication passage inside the valve body of the solenoid valve; When the valve body of the valve is closed,
A variable discharge high pressure pump characterized in that the low pressure passage downstream of the solenoid valve and a space inside the solenoid valve communicating with a communication passage inside a valve body of the solenoid valve are shut off. .