JPH1193803A - Variable displacement high pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform flow amount controlling to an accumulator piping with facility and certainty, even under high engine speed and high pumping ratio, and reduce cost without enlarging a device nor increasing electric power. SOLUTION: A variable displacement high pressure pump is so formed that low pressure fluid is introduced into a pressure chamber 23 prepared by a cylinder 2a and a plunger 21, pressurized and press-fed to a high pressure passage 33. A low pressure control chamber 51 is arranged between the pressure chamber 23 and the feed passage 11, while the pressure inside is controlled by a solenoid valve 6. A check valve 4 is arranged between the low pressure control chamber 51 and the pressure chamber 23, for allowing the fluid to flow only toward the pressure chamber 23. A suction amount of the low pressure fluid to the pressure chamber 23 is controlled by controlling the pressure inside the low pressure control chamber 51 by means of the solenoid valve 6. It is thus possible to control a press-feed amount of the low pressure fluid to an accumulator piping with certainty with a simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable discharge high-pressure pump used for pumping high-pressure fluid in a common rail injection system of a diesel engine, for example.

[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 accumulator pipe is injected into each cylinder by an injector at a predetermined timing (for example,
JP-A-64-73166, etc.).

FIG. 24 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.
An electromagnetic valve 94 is mounted above the pressure chamber 93. The electromagnetic valve 94 is provided with a low-pressure flow path 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 the state shown in the drawing, in which the coil 97 is not energized. When the plunger 92 is lowered, the fuel is supplied from the low-pressure supply pump (not shown) to the low-pressure flow path 95 and the gap around the valve body 96. Through 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 flow path 99 provided on the side wall of the pressure chamber 93.

[0005]

While the plunger 92 is being raised, the valve body 96 is driven by the fuel pressure in the pressure chamber 93.
, A force in the valve closing direction acts on the valve body 96, and once the valve body 96 is closed, the valve does not open even if the current supply to the coil 97 is stopped. 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 rising 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 flow path 95 side, After a while
By closing the valve and starting pressurization, a required amount of pressurized fluid is pressure-fed to the pressure accumulation 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 a force in the valve closing direction due to the throttle effect of the fuel flowing toward the low pressure flow path 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.

SUMMARY OF THE INVENTION It is an object of the present invention to easily and surely control the flow rate of pressure-supplying to a pressure accumulating pipe even when the engine speed is increased and the pump has a high oil supply rate. That is, there is no increase in power. Another object of the present invention is to eliminate a problem such as a response delay caused by using an electromagnetic valve for opening and closing the flow path.

[0010]

According to a first aspect of the present invention, in the variable displacement high pressure pump, a plunger is inserted and disposed in a cylinder so as to be able to reciprocate, and the inner wall surface of the cylinder and the plunger are connected to each other. A pressure chamber is formed with the end face, and the low-pressure fluid introduced from the low-pressure channel into the pressure chamber is pressurized by the reciprocating motion of the plunger and is sent to the high-pressure channel. A low-pressure control chamber disposed between the pressure chamber and the low-pressure flow path; a pressure adjusting unit that adjusts the pressure of the low-pressure control chamber; and a pressure during suction of the low-pressure fluid from the low-pressure control chamber into the pressure chamber. Between the low-pressure control chamber and the low-pressure control chamber, and between the start of pressurization of the low-pressure fluid sucked into the pressure chamber and the end of the pressure supply of the pressurized fluid to the high-pressure flow path. And a check valve for shutting off the gap.

In the above configuration, the low-pressure fluid is sucked into the pressure chamber from the low-pressure control chamber when the check valve is opened, and lowers the plunger. When the suction ends and the check valve closes and the plunger starts to rise, the low-pressure fluid in the pressure chamber is pressurized and sent to the high-pressure flow path. Here, the suction amount of the low-pressure fluid into the pressure chamber depends on the pressure in the low-pressure control chamber. The suction amount is small when the pressure in the low-pressure control chamber is low, and large when the pressure is high. Therefore, by providing a pressure adjusting means for adjusting the pressure in the low-pressure control chamber and adjusting the pressure in the low-pressure control chamber, the amount of suction of the low-pressure fluid into the pressure chamber can be controlled.

As described above, in the above-described configuration, the suction amount of the low-pressure fluid is controlled by the low-pressure control chamber provided in the low-pressure flow path leading to the pressure chamber and the pressure adjusting means for controlling the pressure. Equipped with a check valve to open and close the
All the low-pressure fluid introduced into the pressure chamber via the check valve is pressurized and sent to the high-pressure channel. In other words, the variable discharge amount high pressure pump having the above configuration is a pump of a suction amount control type that controls the pumping amount by controlling the suction amount into the pressure chamber.
There is no need to open the flow path for a certain period of time when the plunger is raised, unlike the conventional pre-stroke control performed by one valve. Therefore, the valve may be closed immediately after the end of inhalation,
The conventional problem of self-closing of the valve element does not occur. In other words, there is no need to increase the size of the device for preventing self-closing or increase the power. Further, the check valve shuts off the pressure chamber and the low-pressure control chamber until the end of the pressurized fluid supply, so that the pressure adjusting means is not affected by the pressurized fluid, and the pressure adjusting means is increased in size. There is no need to increase power or power, and a small-scale configuration for low voltage is sufficient. Further, there is no problem such as a response delay to a valve closing signal as in the case of using a conventional solenoid valve, and the reliability is high.

According to the second aspect of the present invention, the low-pressure control chamber is connected to the return flow path via a throttle, and the pressure adjusting means adjusts the flow rate of the low-pressure fluid flowing from the low-pressure flow path into the low-pressure control chamber. Equipped with a flow control valve.

The low-pressure fluid flows into the low-pressure control chamber via the flow control valve, and the low-pressure fluid flowing into the low-pressure control chamber is sucked into the pressure chamber or flows out of the return passage through a throttle. . Here, the flow rate of the low-pressure fluid into the low-pressure control chamber is adjusted by the flow rate control valve, that is, the pressure in the low-pressure control chamber is controlled by the balance between the inflow amount and the outflow amount, and the suction amount of the low-pressure fluid into the pressure chamber Can be controlled.

According to the third aspect of the present invention, the low-pressure control chamber is connected to the low-pressure flow path via a throttle, and the pressure adjusting means adjusts the flow rate of the low-pressure fluid flowing from the low-pressure control chamber to the return flow path. Equipped with a flow control valve.

The low-pressure fluid flows into the low-pressure control chamber through the throttle, and the low-pressure fluid flowing into the low-pressure control chamber is sucked into the pressure chamber or flows out through the return flow path via a flow control valve. . By adjusting the flow rate of the low-pressure fluid from the low-pressure control chamber by the flow control valve, that is, by controlling the pressure of the low-pressure control chamber by the balance between the inflow rate and the outflow rate, the suction rate of the low-pressure fluid into the pressure chamber is reduced. Can control.

[0017] The flow control valve may be configured as follows.
An electromagnetic valve that opens and closes under the control of energization by the control means. By opening and closing the solenoid valve, the amount of fuel flowing into or out of the pressure control chamber is adjusted.

According to the fifth aspect of the present invention, the control means controls the drive frequency or duty ratio of the solenoid valve to control the pressure in the low-pressure control chamber, and adjusts the low-pressure control chamber to a desired pressure.

According to a sixth aspect of the present invention, there is provided a pressure difference eliminating means for eliminating a pressure difference acting on both end faces of the valve body of the solenoid valve. This prevents fluid pressure from acting on the solenoid valve and improves operability.

In the configuration of claim 7, the valve opening direction of the valve body of the electromagnetic valve is made different from the fluid flow direction at the time of valve opening. Accordingly, it is possible to prevent the force in the valve opening direction from acting when the valve body is closed, thereby preventing malfunction and the like.

The flow regulating valve may be a variable throttle valve which can be freely opened by the control of the control means. The variable throttle valve is constituted by a linear solenoid valve according to a ninth aspect. The amount of fuel flowing into or out of the pressure control chamber is adjusted according to the degree of opening of the variable throttle valve.

According to a tenth aspect of the present invention, the control means controls the pressure in the low-pressure control chamber by controlling the current supplied to the linear solenoid of the linear solenoid valve, thereby controlling the low-pressure control chamber to a desired pressure. Can be adjusted.

The flow regulating valve is provided between the low-pressure control chamber and the return flow path,
By providing a relief valve that is configured to be able to freely open the valve by energization control of the control means, the amount of fuel that flows out of the pressure control chamber is adjusted according to the valve opening pressure of the relief valve.

The relief valve may be of a spring-loaded type and may include an actuator for adjusting a spring force of a spring for setting a valve opening pressure.

According to a thirteenth aspect of the present invention, the pressure adjusting means is provided with a low-pressure fluid discharging means which is configured to be capable of discharging freely and discharges the low-pressure fluid pumped from the low-pressure channel into the low-pressure control chamber. The amount of the low-pressure fluid flowing into the low-pressure control chamber is controlled, and the pressure in the low-pressure control chamber is controlled.

According to a fourteenth aspect of the present invention, the low-pressure fluid discharging means is constituted by a motor pump whose discharge amount is changed by controlling the energization of the control means.

According to a fifteenth aspect, an accumulator for reducing pressure pulsation in the low-pressure control chamber is provided. This can prevent the amount of suction into the pressure chamber from fluctuating under the influence of pressure pulsation.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment 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 below with reference to the drawings. In the system diagram of FIG. 3, the engine E is provided with a plurality of injectors I corresponding to the combustion chambers of the respective cylinders, and these injectors I are connected to a common high-pressure accumulator pipe, a so-called common rail R, for each cylinder. Injection of fuel from the injector I into each combustion chamber of the engine E is controlled by ON / OFF of the injection control solenoid valve B1, and while the solenoid valve B1 is open, fuel in the common rail R is injected by the injector I. It is injected into the engine E. Therefore, it is necessary to continuously accumulate the fuel at a high predetermined pressure corresponding to the fuel injection pressure in the common rail R.
Via the discharge valve B2, the variable discharge amount high pressure pump P of the present invention is connected.

The variable discharge high pressure pump P pressurizes the fuel sucked from the fuel tank T to a high pressure and controls the fuel in the common rail R to a high pressure. The common rail R is provided with a pressure sensor S1 for detecting a common rail pressure. The electronic control unit ECU serving as control means for controlling the system operates such that a signal from the pressure sensor S1 has an optimal value set in advance. Next, the discharge amount of the variable discharge amount high pressure pump P is determined, and a control signal is output to the discharge control device P2. The electronic control unit ECU further includes:
Engine speed sensor S2, TDC (top dead center) sensor S
3. Information on the number of revolutions, the position of the TDC, the accelerator opening, and the temperature is input by the throttle sensor S4 and the temperature sensor S5, and the electronic control unit ECU controls the injection amount according to the engine state determined by these signals. Solenoid valve B
1 to output a control signal.

Next, the details of the variable discharge amount high pressure pump P will be described with reference to FIGS. In the figure, a drive shaft D is rotatably supported in a pump housing 1 via a bearing D2 and a bush D1.
The drive shaft D is connected to a vane type feed pump P1 which sucks up fuel from the fuel tank T (FIG. 3) and supplies the fuel to the feed passage 11 as a low pressure passage. A cam 1 is provided at the right end of the drive shaft D.
The cam 13 rotates together with the drive shaft D at half the speed of the engine. When the cam 13 rotates, the feed pump P1 is moved through the half-moon plate P11.
Of the fuel tank T is rotated by the rotation of the rotor P12.
From the inlet valve B3, a fuel is introduced into the internal space of the feed pump P1 (a space surrounded by the rotor P12, the casing P13, and the covers P14, 15) through a flow path (not shown). The introduced fuel is pressure-fed to the feed flow path 11 via a flow path (not shown) by a vane P16 disposed on the rotor P12 as the rotor P12 rotates.

The fuel in the feed passage 11 is used not only for pressure feeding to a common rail as described below, but also for
It flows into the pump through the throttle passage S and is also used for lubrication inside the pump. The lubricated fuel exits the valve V and is returned to the fuel tank T. Further, the pressure inside the pump is adjusted by the valve V so as to be almost the atmospheric pressure.

A head H is fitted in the right end opening of the pump housing 1, and the head H is inserted into the cam 13 so that the center of the left end protrudes. A plurality of sliding holes 2a as cylinders are provided in the center of the left end of the head H (FIG. 2), and a plunger 21 is supported in each of the plurality of sliding holes 2a in a reciprocating and slidable manner. Have been. A shoe 21a is provided at the outer end of each plunger 21.
, And a cam roller 22 is rotatably held by each shoe 21a. The shoe 21a is slidably held by the guide GD and is movable only in the radial direction. The guide GD is fixed to the head H by a bolt (not shown).

The cam 13 is slidably disposed on the outer periphery of the cam roller 22. A cam surface 13a having a plurality of cam ridges arranged at equal intervals is formed on the inner peripheral surface of the cam 13. I have. The space formed between the inner end surface of each plunger 21 and the inner wall surface of each sliding hole 2a is a pressure chamber 23. Then, drive shaft D
When the cam 13 integrated with the plunger 21 rotates, the plunger 21
Reciprocates in the sliding hole 2 a and pressurizes the fuel in the pressure chamber 23. FIG. 2 shows a state where the plunger 21 is at the highest point.

The pressurized fuel is pressure-fed from a discharge hole 24 (FIG. 1) communicating with the pressure chamber 23 to a common rail R (FIG. 3), which is a pressure accumulation pipe, through a discharge valve 3 fixed to the head H wall. You. The discharge valve 3 has a valve element 31 and a return spring 32 for urging the valve element 31 in the valve closing direction. When the pressurized fuel exceeds a predetermined pressure, the discharge valve 3 opens against the spring force of the return spring 32, and The pressurized fuel is discharged into the discharge passage 33 which is a path.

In FIG. 1, a lock adapter 5 is assembled to the right end of the head H via a stopper 41 and a check valve 4, and a fuel reservoir 12 is formed between the lock adapter 5 and the head H. I have. A space in the left end portion of the lock adapter 5 is a low-pressure control chamber 51, and a pressure-controlling electromagnetic valve 6 for controlling the pressure in the low-pressure control chamber 51 is provided on the right side thereof. I have. A return passage K2 communicating with the inside of the pump (atmospheric pressure) or a return pipe is opened on the side surface of the low-pressure control chamber 51, and the low-pressure control chamber 5 is opened via a throttle K1 provided in the return passage K2.
1 is discharged to the return passage K2.

The solenoid valve 6 is configured to open and close a passage 52 communicating with the feed passage 11 through the fuel reservoir 12 and the low-pressure control chamber 51. The amount of feed fuel, which is a low-pressure fluid, flowing into the chamber 51 is controlled. The amount of fuel suctioned into the pressure chamber 23 is controlled by adjusting the pressure in the low-pressure control chamber 51 based on the balance between the amount of inflow and the amount of outflow from the low-pressure control chamber 51 through the throttle K1.
The throttle K1 is useful, for example, when it is desired to suddenly reduce the pressure in the low-pressure control chamber 51. By closing the solenoid valve 6, the fuel in the low-pressure control chamber 51 is discharged from the throttle K1. The above control can be easily performed.

As shown in FIG. 4A, the check valve 4 has a flow path 43 penetrating the housing 42 in the left-right direction.
A valve body 44 for opening and closing the flow path 43 is provided. The channel 43
Is enlarged in the direction of the pressure chamber 23 (left side in the drawing) to form a conical seat surface 45, and the valve body 44 is urged rightward by a spring 46 held in the stopper 41. It is seated on the seat surface 45. As described above, the check valve 4 is closed in the state shown in the figure, and is opened by the pressure of the fuel flowing into the low-pressure control chamber 51 via the electromagnetic valve 6. At this time, fuel flows into the pressure chamber 23 (FIG. 1) through the seat surface 45 of the check valve 4 and the flow path in the stopper 41. The valve body 44 closes when the pressurization of the pressure chamber 23 is started, and holds the valve until the fuel pumping is completed.
In addition, the valve body 44 has four outer circumferential surfaces as shown in FIG.
There is a groove 44a extending in the axial direction at a location, and fuel flows along the groove 44a.

As shown in FIG. 5, the solenoid valve 6 has a housing 61 containing a coil 62 and a valve body 71 fitted and fixed to the left end thereof. Is fixed to the lock adapter 5. A needle valve 73 is slidably held in a cylinder 72 formed in the valve body 71, and opens and closes between an annular flow path 74a of the valve body 71 and a flow path 74c on the left side of the needle valve 73. It is done. That is, a substantially conical seat surface 75 is formed at the right end of the flow path 74c, and the substantially conical tip of the needle valve 73 is seated on the seat surface 75, and the flow path 7
The space between 4a and 74c is closed. An armature 64 is press-fitted and fixed to the right end of the needle valve 73 and faces the stator 65 at a predetermined interval. A spring 6 is provided in a spring chamber 66 formed in the stator 65.
7 is disposed coaxially with the needle valve 73, and has an armature 64.
Is constantly biased to the left. When the coil 62 is energized, the armature 64 integrated with the needle valve 73 is attracted by the stator 65 and displaces rightward, and the flow path 74a and the flow path 74
and c.

The annular flow path 74a includes a flow path 74b of the valve body 71, a fuel reservoir 53 formed between the valve body 71 and the lock adapter 5, a flow path 52 in the lock adapter 5, and a feed path for the head H. It communicates with the feed channel 11 of the housing 1 via the channel 11a,
The flow path 74c communicates with the low-pressure control chamber 51.

Here, the needle valve 73 has a sliding portion 73a.
Is made equal to the diameter of the seat edge 73b (the contact edge with the seat surface 75 when the valve is closed). When the valve is closed, the fuel supplied into the flow path 74a around the needle valve 73 balances the force of pushing the needle valve 73 leftward and the force of pushing rightward, so that no hydraulic action force is generated by the feed fuel. The needle valve 73 has a communication hole 7 serving as a pressure difference eliminating means penetrating the needle valve 73 along the axis.
6 is formed so that the fuel is always introduced to the right of the needle valve 73. This prevents the needle valve 73 from malfunctioning due to the hydraulic force. In addition, a filter is usually provided in the middle of the fuel flow path reaching the flow path 74a to prevent foreign substances from entering between the needle valve 73 and the seat surface 75 to be constantly opened. The filter may be made of, for example, a metal mesh and its opening may be smaller than the flow path area of the needle valve 73 at the time of the maximum lift.

When the coil 62 is not energized, the end of the needle valve 73 is seated on the seat surface 75 of the valve body 71, and the flow path 74c becomes a communication path with the low-pressure control chamber 51. Is closed. 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 fed when the coil 62 is damaged. When the distal end of the needle valve 73 is separated from the seat surface 75 by energization of the coil 62, the fuel pool 12, the flow channel 52 in the lock adapter 5, the fuel pool 53, the flow channel 74a, the electromagnetic valve 6 The fuel flows into the low-pressure control chamber 51 through the seat surface 75 and the flow path 74c. The solenoid valve 6 and the check valve 4 constitute the discharge control device P2 in FIG.

Next, the variable discharge high pressure pump P
The operation of will be described. The variable discharge amount high pressure pump P
The suction and pressure-feeding process is performed four times per one rotation of the cam 13, and the amount of the pressure-feeding is controlled by the amount of fuel sucked into the pressure chamber 23. Here, the suction amount Q is represented by the following equation. Suction volume Q = α × S × √ (ΔP) × time α: flow coefficient S: opening area of check valve 4 ΔP: pressure of low-pressure control chamber 51 Time: determined by pump rotation speed That is, α, S, time When it is constant, it is understood that the suction amount Q can be controlled by adjusting the pressure in the low-pressure control chamber 51. That is, the higher the pressure in the low-pressure control chamber 51, the larger the suction amount, and the lower the pressure, the smaller the suction amount. The pressure in the low-pressure control chamber 51 can be adjusted by changing the drive frequency and the duty ratio (the energization period) of the solenoid valve 6.

FIG. 6 shows a method of controlling the variable discharge high pressure pump P, in which the operation of the solenoid valve 6, the change in the pressure of the low pressure control chamber 51, and the lift of the cam 13 and the plunger 21 are shown in comparison. , (A) when the inhalation amount is small, (b)
Is the case where the inhalation amount is large. The pressure in the low-pressure control chamber 51 is
By controlling the amount of fuel flowing into the low-pressure control chamber 51 by controlling the energization of the solenoid valve 6 by the electronic control unit ECU (FIG. 3), it is possible to control the pressure between the atmospheric pressure and the pump feed pressure.

When the solenoid valve 6 is on, the low pressure control chamber 51
The pressure in the low-pressure control chamber 51 rises because the inflow amount into the low-pressure control chamber 51 exceeds the outflow amount from the low-pressure control chamber 51. When the solenoid valve 6 is off, the fuel in the low-pressure control chamber 51 only flows out to the return flow path K2, and the pressure in the low-pressure control chamber 51 decreases. Therefore, the low-pressure control chamber 51 is controlled according to the duty ratio of the solenoid valve 6.
Pressure can be adjusted. 6, the low-pressure control room 5
The pressure in the pressure chamber 2 is the same as that in the actual operation (solid line).
3 also shows an imaginary thing (broken line) indicating that there is no intake of fuel to 3. In an actual operation, the pressure in the pressure control chamber 51 is slightly lower than that when no fuel is sucked, because the low-pressure control chamber 51 sucks low-pressure fuel.

When the suction amount is small, the solenoid valve 6
Is made small. By keeping the pressure in the low-pressure control chamber 51 low, the suction of the low-pressure fuel into the pressure chamber 23 is made gradual during the suction stroke of the cam 13 (from the time point a to the time point b). At this time, the cam roller 22 and the cam 13 of the plunger 21 do not come into sliding contact with each other, and the plunger 21 gradually descends (moves in a radial direction, see FIG. 2) with the intake of fuel. Cam 13
Comes into contact with the cam roller 22 and the plunger 21 starts to rise (moves in the radial center direction) (point b in the figure), and then enters the pressure feeding stroke (point a to point b). That is, the plunger 21 is raised by the pushing force of the cam 13 against the cam roller 22, and the fuel in the pressure chamber 23 is pressurized.
It is pumped to the common rail R.

In this pressure feeding process, the pressure of the pressurized fuel is applied to the check valve 4, so that the valve body 44 does not open.
Therefore, the amount of suction into the pressure chamber 23 is the amount of pressure feed, and the control of the common rail pressure can be easily performed. Further, since the fuel in the pressure chamber 23 is not sucked during the pressure feeding, the pressure in the low-pressure control chamber 51 increases again during the ON period of the solenoid valve 6 and attempts to return to the state shown by the broken line.

To increase the suction amount, the duty ratio of the solenoid valve 6 is increased. As a result, the amount of feed fuel delivered from the feed pump P1 into the low-pressure control chamber 51 increases, and the pressure in the low-pressure control chamber 51 approaches the feed pressure. Thus, the inflow speed from the low-pressure control chamber 51 to the pressure chamber 23 increases, and the plunger 21 descends at a high speed, abuts the rising cam 13 at an early timing, and the pressure chamber 23
Then, a larger amount of low-pressure fuel is sucked in than in the case of FIG.

As described above, as the duty ratio of the solenoid valve 6 increases, the stroke of the plunger 21 increases,
Inhalation volume increases. Here, the pumping amount per operation is represented by plunger lift × plunger diameter × plunger number (4 in the example in the figure).

FIG. 7 shows the pumping characteristics in the case where the control is performed as described above. The electronic control unit ECU (FIG. 3) controls the duty ratio of the solenoid valve 6 to reduce the pumping amount to a desired pumping amount. It can be controlled accurately. Note that the maximum value of the pumping amount depends on the cam lift.

As described above, in the above configuration, the amount of fuel sucked into the pressure chamber 23 is controlled by the low pressure control chamber 51 and the solenoid valve 6, and the check valve 4 is provided between the low pressure control chamber 51 and the pressure chamber 23. Is provided to pressurize all the fuel sucked into the pressure chamber 23 and send it to the common rail R under pressure. In this suction amount control method, since the control of the fuel suction amount and the opening and closing of the flow path to the pressure chamber 23 are performed separately, after the plunger 21 moves to the rising stroke as in the conventional pre-stroke control,
There is no need to open the flow path, and the problem of self-closing of the valve element does not occur. The cost can be reduced by using the check valve 4 having a simple structure, and the check valve 4 operates immediately at the start of pressurization without the problem of response delay unlike the solenoid valve. Excellent. Further, since no high pressure is applied to the solenoid valve 6 for controlling the pressure of the low-pressure control chamber 51, the spring force for return may be small, and the coil 62 for generating the attraction force may be small. Can be. However, with the above configuration, it is possible to easily and reliably control the flow rate of pressure-feeding to the high-pressure flow path with a simple configuration, and it is not necessary to increase the size of the device or increase the power.

FIG. 8 is a flowchart showing an example of control by the electronic control unit ECU. As shown in the system diagram of FIG. 3, various kinds of information are constantly input to the electronic control unit ECU from the respective sensors, and the engine (from the NE signal detected by the engine speed sensor S2) receives the engine ( Pump) The number of revolutions is calculated from the accelerator opening detected by the throttle sensor S4 and a target common rail pressure (CPTRG) and an injection amount (a pumping amount) based on a previously input control map (step (1), step) (2)). Subsequently, a drive frequency and a duty ratio (an energizing period) of the electromagnetic valve 6 according to the pump rotational speed and the pumping amount are calculated (step (3)), and the electromagnetic valve 6 is energized.

The electronic control unit ECU always detects the common rail R pressure (CPACT) by the pressure sensor S1, and detects the detected common rail R pressure (CPACT) and the target common rail pressure (CPACT).
TRG) (step (4)), and if different, correct. As the correction method, (CPACT-C
(PTRG) is calculated to calculate the required increase in the amount of pumping (step (5)), and the drive frequency and the duty ratio (the energizing period) corresponding to the increase are changed (step (6)). Then, again, (CPACT = CPTRG)
(Step (7)), and (CPACT =
If not (CPTRG), the flow returns to step (5) to repeatedly perform feedback control until (CPACT = CPTRG).

(Second Embodiment) FIG. 9 shows a second embodiment of the present invention. In the first embodiment, the feed fuel is supplied to the low-pressure control chamber 51 via the solenoid valve 6 (see FIG. 1). However, in the present embodiment, as shown in FIG. Flow path 52 communicating with the low pressure control chamber 5
1 is connected directly to the lower surface, and a throttle 54 is provided in the middle of the flow path 52. On the other hand, a discharge path communicating with the inside of the pump P (atmospheric pressure) or the return pipe (atmospheric pressure) is formed from the fuel pool 53 around the pressure control solenoid valve 6A through the return flow path 55 in the lock adapter 5. The pressure in the low-pressure control chamber 51 is controlled by opening and closing the solenoid valve 6 to control the amount of fuel flowing out of the low-pressure control chamber 51. Note that the portions denoted by the same reference numerals as those in FIGS. 1 to 5 perform substantially the same operation, and therefore the description will be made focusing on the differences from the first embodiment.

FIG. 10A shows the electromagnetic valve 6A. The solenoid valve 6A includes a cylinder 7 formed on a valve body 71A.
A needle valve 73A is slidably held at 2A.
The needle valve 73A has a constricted portion, and the step portion of the left end portion 77 is formed in a conical shape, and has a conical surface 73c. Opposite to the conical surface 73c, a conical surface 75A that expands in diameter to the left is formed in the cylinder 72A and serves as a seat surface 75A. With such a configuration, the flow path 74a and the flow path 74c communicate with each other in the non-energized state shown in the figure, and when the coil 62 is energized, the needle valve 73A is displaced to the right and the conical surface 73c is connected to the seat surface 75A. The flow path 74a and the flow path 74c are in close contact with each other and are blocked. That is, it has a normally open structure.

At this time, all the fuel flowing from the throttle 54 flows out from the solenoid valve 6A to the return flow path 55 side (atmospheric pressure), and is prevented from being sucked into the pressure chamber 23. That is, since the feed fuel flows into the low-pressure control chamber 51 from the low-pressure flow path 52, the pressure in the low-pressure control chamber 51 does not become completely zero, so that the check valve 4 does not open due to the pressure. The spring force of the fourth spring 46 may be adjusted.

When the coil 62 of the solenoid valve 6A is energized and the needle valve 73 is closed, the fuel flowing from the throttle 54 increases the pressure in the low-pressure control chamber 51, and the amount of fuel corresponding to this pressure is reduced. It is sucked into the chamber 23. Here, the pressure in the low-pressure control chamber 51 can be adjusted by the balance between the amount of inflow from the throttle 54 and the amount of outflow from the solenoid valve 6A. That is, to reduce the suction amount, the solenoid valve 6A
And the outflow from the solenoid valve 6A to the return passage 55 is increased. Thus, similarly to the first embodiment, the pressure in the low-pressure control chamber 51 decreases, and the amount of suction into the pressure chamber 23 decreases. To increase the suction amount, the duty ratio of the solenoid valve 6A is increased, and the return flow path 5
Reduce outflow to 5. Thus, as in the first embodiment, the pressure in the low-pressure control chamber 51 increases, and the amount of suction into the pressure chamber 23 increases. The operation of each part of the pump is substantially the same as in FIG.

The needle valve 73A is shown in FIG.
As described above, a communication hole 76 for communicating between the left and right end surfaces is provided inside to prevent malfunction due to a pressure difference applied to both end surfaces.

With the above configuration, the amount of pressure feed can be controlled with high accuracy in accordance with the duty ratio of the solenoid valve 6A.
In addition, if the solenoid valve 6A has a normally closed structure in the above configuration, the fuel supplied into the low-pressure control chamber 51 when the coil 62 is disconnected may always be fully sucked (pumped). Because of the structure, this can be prevented.

(Third Embodiment) FIG. 11 shows a third embodiment of the variable discharge high pressure pump according to the present invention. This is the same as the first embodiment except that the solenoid valve as the pressure adjusting means is replaced with a linear solenoid valve (variable throttle valve) as a throttle valve. In the figure, portions having the same numbers perform substantially the same operation, and therefore, the description will be focused on the differences from the first embodiment.

As shown in FIG. 12, the variable throttle valve 6B has a housing 61B containing a coil 62B and a valve body 71B fitted and fixed in the left end thereof, and is provided in a cylinder 72B provided in the valve body 71B. , Valve element 73B
Is slidably held.

A valve body 73B is provided inside the valve body 71B.
B, a flow path 74e is formed so as to surround the valve body 73B.
A flow path 74g is formed on the downstream side, and communicates with the low-pressure control chamber 51. A seat surface 75B is formed at the opening end of the flow path 74g on the valve body 73B side, and the coil 62B
The valve 73B is seated on the seat surface 75B and shuts off between the flow paths 74e and 74g in the state shown in FIG.

An armature 64B is press-fitted and fixed to the right end of the valve body 73B, and the armature 64B is fixed to a stator 65B.
And a coil 62B is disposed outside the stator 65B. A spring 67B has a valve body 73 in a spring chamber 66B formed inside the stator 65B.
Arranged coaxially with B, it urges the armature 64B to the left in the figure.

The portion 65a of the stator 65B facing the armature 64B has a tapered shape in which the sectional area decreases toward the armature 64B. Therefore, armature 64B
The lift amount of the valve body 73B integrated with the coil 62B
Armature 6 of stator 65B determined by the amount of electricity
4B and the spring force of the spring 67B. That is, the variable throttle valve 6B is a linear solenoid valve in which the position of the valve body 73B is variable in accordance with the amount of current supply. The energization control is performed by an electronic control unit ECU (see FIG. 3) as control means.

FIG. 13 is an enlarged view of the valve portion of the variable throttle valve 6B. The valve body 73B is a rod-shaped member having a seat surface 75B side formed in a conical shape. The valve diameter d1 is 3.0 mm, the inclination angle θ1 of the conical surface 73c is 30 °, and the seat surface 75B on the flow path 74g side has a right end diameter. d2 is 3.1 mm, inclination angle θ2 is 28
°.

Since the structure of the distal end of the valve body 73B is as described above, the conical surface 73c of the valve body 73B when the valve is closed.
The seal edge 73d is tightly attached to the sheet surface 75B, and the flow path 74e, 74g is shut off. Therefore, the valve body 73B
When the valve is closed, the flow path 74e and therefore the fuel pool 53
No pressure is applied in the valve opening direction. Further, since the communication hole 76 penetrating therethrough is also formed inside the valve body 73B, the pressures acting on the left and right end surfaces of the valve body 73B are balanced, and even when the valve is opened, the valve body 73B is opened.
No oil pressure acts on, and stable operation can be obtained. Further, since no oil pressure acts on the valve body 73B as described above, the spring force of the spring 67B may be small, and stable operation is possible even with a linear solenoid valve having a small suction force on the armature 64B.

In this embodiment, the valve body 73B
Although the diameter of the seal edge 73d is made equal to the diameter of the valve, the diameter may be slightly reduced as long as the operation of the valve body 73B does not become defective.

FIG. 14 shows the operation of the variable throttle valve 6B, the change in the pressure in the low-pressure control chamber 51, and the lift of the cam 13 and the plunger 21. FIG. 14A shows the case where the suction amount is small, and FIG. ) Indicates a case where the inhaled amount is large.

In order to make the suction amount small, the amount of current to the coil 62B is made small, the lift amount of the valve body 73B of the variable throttle valve 6B is made small, and the opening degree is made small. Thereby, the inflow from the low-pressure flow path 52 to the low-pressure control chamber 51 is reduced. Then, similarly to the first embodiment, the pressure in the low-pressure control chamber 51 decreases,
The amount of suction into the pressure chamber 23 is reduced.

In order to increase the suction amount, the amount of current supplied to the coil 62B is increased to increase the lift amount of the valve body 73B of the variable throttle valve 6B, thereby increasing the opening. Thereby, the inflow from the low-pressure flow path 52 to the low-pressure control chamber 51 increases. Then, as in the first embodiment, the pressure in the low-pressure control chamber 51 increases,
The suction amount into the pressure chamber 23 increases.

FIG. 15 shows the pressure feeding characteristics when the above-described control is performed. The electronic control unit ECU controls the amount of current supplied to the variable throttle valve 6B so that the amount of pressure feeding can be accurately controlled.

FIG. 16 is a flowchart showing an example of control by the electronic control unit ECU. After calculating the target common rail pressure (CPTRG) and the injection amount (pumping amount) (step (2)), the energization amount of the variable throttle valve 6B according to the pump speed and the pumping amount is calculated (step (3)
A)), the current is supplied to the variable throttle valve 6B.

Further, the electronic control unit ECU compares the detected common rail R pressure (CPACT) with the target common rail pressure (CPTRG) (step (4)), and if different, (CPACT-CPTR)
G) is calculated to calculate the necessary increase in the pumping amount (step (5)), and based on this increase, the current value of the variable throttle valve 6B is changed so that the necessary pumping amount is increased ( Step (6A)). Then, again, (CPACT =
CPTRG) (step (7)),
Step (5) until (CPACT = CPTRG)
Step (7) is repeated.

(Fourth Embodiment) FIG. 17 shows a variable discharge high pressure pump according to a fourth embodiment of the present invention. This is the same as the second embodiment except that the solenoid valve as the pressure adjusting means is replaced by a linear solenoid valve (variable throttle valve). In the figure, the portions denoted by the same reference numerals perform substantially the same operation, and therefore, the description will focus on the differences from the second embodiment.

The variable throttle valve 6B is the same as that of the third embodiment, and a flow path 74g communicates with the low-pressure control chamber 51. The return flow path 55 communicates with the flow path 74e via the fuel reservoir 53. The amount of outflow from the low pressure control chamber 51 to the return passage 55 is controlled by the variable throttle valve 6B.

FIG. 18 shows the operation of the variable throttle valve 6B, the change in the pressure in the low-pressure control chamber 51, and the lift of the cam 13 and the plunger 21 in comparison. ) Indicates a case where the inhaled amount is large.

In order to reduce the suction amount, contrary to the third embodiment, the amount of current to the coil 62B is increased to increase the lift amount of the valve body 73B and increase the opening degree. Thereby, the outflow from the low-pressure control chamber 51 to the return flow path 55 increases.
Thus, similarly to the second embodiment, the pressure in the low-pressure control chamber 51 decreases, and the amount of suction into the pressure chamber 23 decreases.

To increase the suction amount, the amount of current supplied to the coil 62B is reduced to reduce the lift amount of the valve body 73B, thereby reducing the opening. Thereby, the outflow from the low pressure control chamber 51 to the return flow path 55 is reduced. Thus, as in the second embodiment, the pressure in the low-pressure control chamber 51 rises, and
The amount of inhalation into the air increases.

In the configuration of this embodiment, the electronic control unit E
The CU controls the amount of current supplied to the variable throttle valve 6B,
The amount of pumping can be controlled accurately.

(Fifth Embodiment) FIG. 19 shows a fifth embodiment of the variable discharge high pressure pump according to the present invention. This is obtained by replacing the solenoid valve as the pressure adjusting means with a relief valve in the configuration of the second embodiment. In the figure, portions having the same numbers perform substantially the same operation, and therefore, the description will be focused on the differences from the first embodiment.

The lock adapter 5 has a hole 501 formed on the right side of the low-pressure control chamber 51, and communicates with the low-pressure control chamber 51 via a flow path 57.

The relief valve 6C comprises a valve section 601 and a step motor 602 as an actuator. The valve section 601 has a stepped valve body 71C in which a cylinder 72C is formed. The valve body 71C is fitted in the hole 501, and is fixed to the lock adapter 5 by a bolt (not shown) together with a step motor 602 disposed on the right side of the valve body 71C. Valve body 71
A fuel reservoir 53 is formed on the outer periphery of the left half of the small diameter of C,
The fuel reservoir 53 is in communication with the return channel 55. A flow path 74j is formed through the peripheral wall of the valve body 71C. At the position of the communication flow path 57 of the valve body 71C, a flow path 74h is formed penetrating the left end wall.
And the cylinder 72C.

A valve body 73C is slidably provided in the cylinder 72C of the valve body 71C in the left-right direction. A flow path 74i is formed on the outer periphery of the valve body 73C, and communicates with the fuel reservoir 53 via a flow path 74j. The valve body 73C is
A tapered conical portion 77 is provided facing the open end of the flow path 74h, and is opened or closed to communicate or block the low-pressure control chamber 51 and the return flow path 55.

A spring 67C is provided on the right side of the valve body 73C.
Is arranged. The spring 67C has a step motor 6
The valve body 73C is pinched and compressed by the rod 68 and the valve body 73C that advance from 02, and urges the valve body 73C to the left, that is, the valve closing direction. Then, the pressure of the low pressure control chamber 51 is
When the valve opening pressure exceeds the valve opening pressure defined by the spring force of the valve C, the valve body 73C separates and fuel flows from the low pressure control chamber 51 to the return passage 55.
And the low pressure control chamber 51 is maintained at the valve opening pressure.

The stepping motor 602 is a direct-acting type in which the amount of advance of the rod 68 changes, and the rod 68 moves forward and backward in proportion to the number of energizing pulses transmitted from the electronic control unit ECU as control means. The advance amount of the rod 68 is controlled by feedback control by the electronic control unit ECU. When the amount of advance is large, the amount of compression of the spring 67C increases and the spring force increases. When the amount of advance is small, the amount of compression of the spring 67C decreases and the spring force decreases. As described above, the valve opening pressure of the relief valve 6C can be adjusted.

FIG. 20 shows the operation of the relief valve 6C, the change in the pressure in the low-pressure control chamber 51, and the lift of the cam 13 and the plunger 21. FIG. 20A shows the case where the suction amount is small, and FIG. Is the case where the inhalation amount is large.

In order to make the suction amount small, the spring force of the spring 67C is made small by making the rod 68 advance amount small, and the valve opening pressure is made small. As a result, the pressure in the low-pressure control chamber 51 is maintained on the low-pressure side, and the amount of fuel sucked into the pressure chamber 23 decreases.

In order to increase the suction amount, the spring force of the spring 67C is increased by increasing the rod 68 advance amount, and the valve opening pressure is increased. As a result, the pressure in the low-pressure control chamber 51 is maintained on the high-pressure side, and the amount of fuel suction into the pressure chamber 23 increases.

In the configuration of this embodiment, the electronic control unit E
The CU controls the energizing pulse of the step motor 602, so that the amount of pumping can be accurately controlled.

(Sixth Embodiment) FIG. 21 shows a sixth embodiment of the variable discharge high pressure pump according to the present invention. This differs from the configuration of the first embodiment in that the configuration for delivering low-pressure fuel to the pressure chamber is different from that of the first embodiment, and another feed pump is used in place of the feed pump operated by engine power. In the figure, portions having the same numbers perform substantially the same operation, and therefore, the description will be focused on the differences from the first embodiment.

The feed pump operated by the power transmitted from the drive shaft D is omitted, and the drive shaft D is connected only to the cam 13.

A lock bolt 5A is screwed into the head H to the right of the check valve 4, and the check valve 4 is fixed to the head H.

The lock bolt 5A has a fuel reservoir 53 formed on the outer periphery of the left half of the small diameter. The lock bolt 5A is formed with a vertical hole 58a that is open on the left end face, and
a, a lateral hole 58b opened in the peripheral wall surface is formed as a flow path 58b, and the check valve 4 and the fuel reservoir 53A are formed.
And let them communicate. The head H has a fuel pool 5
A channel 59 communicating with 3A is formed, and a channel 58a,
The low pressure control chamber 51A is formed by the flow path 58b, the fuel reservoir 53A, and the flow path 59. The channel 59 communicates with the discharge port of the feed pump 5D.

[0093] The feed pump 6D is a motor-driven pump, and is a supply pipe T1 serving as a low-pressure flow path communicating with the fuel tank T.
, And pumps up a low pressure fluid fuel from the fuel tank T and feeds it. Feed pump 6
In D, the oil supply amount increases with an increase in the amount of energization, and the energization control is performed by an electronic control unit ECU serving as control means.

The flow path 59 communicates with the throttle flow path S, and fuel for lubrication is supplied from the feed pump 6D to the inside of the pump.

FIG. 22 shows the current supplied to the feed pump 6D,
A change in pressure in the low-pressure control chamber 51 and a lift of the cam 13 and the plunger 21 are shown in comparison with each other, where (a) shows a case where the suction amount is small and (b) shows a case where the suction amount is large.

In order to reduce the suction amount, the supplied current is reduced, and the amount of oil supplied to the low-pressure control chamber 51A is reduced. As a result, the pressure in the low-pressure control chamber 51 is maintained on the low-pressure side, and the amount of fuel sucked into the pressure chamber 23 decreases.

To increase the suction amount, the energizing current is increased and the amount of oil supplied to the low-pressure control chamber 51A is increased. As a result, the pressure in the low-pressure control chamber 51A is maintained on the high-pressure side, and the amount of fuel sucked into the pressure chamber 23 increases.

In the configuration of this embodiment, the electronic control unit E
The CU controls the current supplied to the feed pump 6D, so that the pumping amount can be accurately controlled. In addition, the flow control valve such as the solenoid valve, the variable throttle valve, and the relief valve of each of the above embodiments is not required, and the pump main body does not need to be incorporated in the pump main body, so that the pump main body can be downsized.

(Seventh Embodiment) FIG. 23 shows a seventh embodiment of the present invention. In the configuration of the first embodiment, the difference between the suction amount cycles caused by the pressure pulsation of the low-pressure control chamber is reduced to further improve the suction amount control. In the figure, portions having the same numbers perform substantially the same operation, and therefore, the description will be focused on the differences from the first embodiment.

The accumulator 8 is provided on the upper wall of the lock adapter 5. The accumulator 8 has a piston 82 slidably disposed in a housing 81 screwed to an upper wall of the lock adapter 5, and forms an accumulator chamber 83 between the lower surface of the piston 82 and the inner wall of the lock adapter 5. Become. The piston 82 has a spring 84 above it.
Urged downward. In addition, lock adapter 5
Inside, there is provided a passage 85 that communicates between the accumulator chamber 83 and the low-pressure control chamber 51.

With this configuration, when the pressure in the low-pressure control chamber 51 increases, fuel flows into the accumulator chamber 83 through the passage 85 and the piston 82
This is absorbed by pushing up. Therefore, the pressure fluctuation in the low-pressure control chamber 51 can be suppressed, and the inter-cycle fluctuation of the suction amount can be prevented.

In each of the above embodiments, the example of the variable displacement high-pressure pump of the inner cam pressure feed type has been described. However, the present invention is not limited to this. Of course, it may be applied.

[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 a sectional view taken along line AA of FIG.

FIG. 3 is an overall configuration diagram of a fuel injection system including a variable discharge high-pressure pump according to the first embodiment.

4A is a partially enlarged cross-sectional view of FIG. 1, and FIG.
FIG. 3 is a cross-sectional view taken along line BB in FIG.

FIG. 5 is a cross-sectional view of a solenoid valve of the variable discharge high-pressure pump according to the first embodiment.

FIGS. 6A and 6B are time charts showing the operation of the variable discharge high pressure pump according to the first embodiment.

FIG. 7 is a graph showing an operation of the variable discharge high pressure pump according to the first embodiment.

FIG. 8 is a flowchart illustrating a control method of the variable discharge high pressure pump according to the first embodiment.

FIG. 9 is an overall sectional view of a variable discharge high-pressure pump according to a second embodiment.

FIG. 10A is a cross-sectional view of a solenoid valve of a variable discharge high pressure pump according to a second embodiment, and FIG. 10B is a needle valve of the solenoid valve.

FIG. 11 is an overall sectional view of a variable discharge high-pressure pump according to a third embodiment.

FIG. 12 is a cross-sectional view of a variable throttle valve of the variable discharge high-pressure pump according to the third embodiment.

FIG. 13 is a partially enlarged view of FIG.

FIGS. 14A and 14B are time charts each showing the operation of the variable discharge high pressure pump according to the third embodiment.

FIG. 15 is a graph showing the operation of the variable discharge high pressure pump according to the third embodiment.

FIG. 16 is a flowchart illustrating a control method of the variable discharge high pressure pump according to the third embodiment.

FIG. 17 is an overall cross-sectional view of a variable discharge high-pressure pump according to a fourth embodiment.

FIGS. 18A and 18B are time charts showing the operation of the variable discharge high pressure pump according to the fourth embodiment.

FIG. 19 is an overall cross-sectional view of a variable discharge high-pressure pump according to a fifth embodiment.

FIGS. 20A and 20B are time charts showing the operation of the variable discharge high pressure pump according to the fifth embodiment, respectively.

FIG. 21 is an overall sectional view of a variable discharge high-pressure pump according to a sixth embodiment.

FIGS. 22 (a) and 22 (b) are time charts showing the operation of the variable discharge high pressure pump according to the sixth embodiment.

FIG. 23 is an overall sectional view of a variable discharge high-pressure pump according to a seventh embodiment.

FIG. 24 is a partial sectional view of a conventional variable discharge high pressure pump.

[Explanation of symbols]

P variable discharge high pressure pump P1 feed pump 1 pump housing 11 feed passage (low pressure passage) 12 fuel reservoir 13 cam 2a sliding hole (cylinder) 21 plunger 22 cam roller 23 pressure chamber 24 discharge hole 3 discharge valve 31 valve body 32 Return spring 33 Discharge passage (high pressure passage) 4 Check valve 41 Stopper 42 Housing 43 Flow passage 44 Valve body 45 Seat surface 5 Lock adapter 51, 51A Low pressure control chamber 52 Flow passage (Low pressure passage) 53 Fuel reservoir 54 Throttle 55, K2 Return flow path 6, 6A Solenoid valve for pressure control (pressure adjusting means, flow adjusting valve) 67 Communication hole (pressure difference eliminating means) 6B Variable throttle valve (pressure adjusting means, flow adjusting valve) 602 Step motor (actuator) ) 6C relief valve (pressure regulating means, flow regulating valve) 67, 67A, 67B , 67C Spring 6D Feed pump (pressure adjusting means) 73C Valve 8 Accumulator T1 Supply pipe (low pressure passage) ECU Electronic control unit (control means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // F02M 47/02 F02M 47/02 (72) Inventor Showa Kojima 1-1-1, Showa-cho, Kariya-shi, Aichi Pref.

Claims (15)

[Claims] A pressure chamber formed by an inner wall surface of the cylinder and an end face of the plunger, and introduced into the pressure chamber through a low-pressure flow path. In a variable discharge high pressure pump adapted to pressurize the low pressure fluid by the reciprocating motion of the plunger and pressurize to the high pressure flow path, a low pressure control chamber disposed between the pressure chamber and the low pressure flow path, A pressure adjusting means for adjusting the pressure of the low-pressure control chamber; and, when sucking the low-pressure fluid from the low-pressure control chamber into the pressure chamber, a communication between the pressure chamber and the low-pressure control chamber. A check valve that shuts off the pressure chamber and the low-pressure control chamber between the start of pressurization of the low-pressure fluid and the end of pressurization of the pressurized fluid to the high-pressure channel. Variable discharge high pressure pump. 2. The low pressure control chamber is connected to a return flow path via a throttle, and the pressure adjusting means includes a flow control valve for adjusting a flow rate of a low pressure fluid flowing from the low pressure flow path into the low pressure control chamber. The variable discharge high pressure pump according to claim 1 provided. 3. The low-pressure control chamber is connected to the low-pressure flow path via a throttle, and the pressure adjusting means includes a flow control valve for adjusting a flow rate of the low-pressure fluid flowing from the low-pressure control chamber to the return flow path. The variable discharge high pressure pump according to claim 1 provided. 4. The variable discharge amount high pressure pump according to claim 2, wherein the flow rate adjusting valve is an electromagnetic valve that opens and closes under the control of energization of a control means. 5. The variable discharge amount high pressure pump according to claim 4, wherein said control means controls the pressure of said low pressure control chamber by controlling a drive frequency or a duty ratio of said solenoid valve. 6. A pressure difference eliminating means for eliminating a pressure difference acting on both end faces of a valve body of said solenoid valve.
Or the variable discharge high pressure pump according to any one of the above items 5. 7. The variable discharge high pressure pump according to claim 4, wherein the valve opening direction of the valve body of the solenoid valve and the flow direction of the fluid at the time of valve opening are made different. 8. The variable discharge amount high pressure pump according to claim 2, wherein the flow rate adjusting valve is a throttle valve configured to be freely openable by an energization control of a control means. 9. The variable discharge amount high pressure pump according to claim 8, wherein said throttle valve is constituted by a linear solenoid valve having a linear solenoid for driving a valve body to a predetermined position in accordance with an amount of electricity. 10. The variable discharge high pressure pump according to claim 9, wherein the control means controls the pressure in the low pressure control chamber by controlling a current supplied to the linear solenoid. 11. The variable valve according to claim 3, wherein the flow control valve is a relief valve provided between the low-pressure control chamber and the return flow passage, the valve being configured to be able to freely open the valve under the control of energization of a control means. Discharge high pressure pump. 12. The variable discharge high pressure pump according to claim 11, wherein said relief valve is of a spring-loaded type and is provided with an actuator for adjusting a spring force of a spring for setting a valve opening pressure. 13. The variable pressure control means according to claim 1, wherein said pressure adjusting means comprises a low pressure fluid discharging means configured to discharge the low pressure fluid pumped from said low pressure flow path into said low pressure control chamber. Discharge high pressure pump. 14. The variable discharge high pressure pump according to claim 13, wherein said low pressure fluid discharge means is constituted by a motor pump whose discharge amount is changed by control of energization of a control means. 15. The variable discharge high pressure pump according to claim 1, further comprising an accumulator for reducing pressure pulsation in the low pressure control chamber.