JPH11159446A - Hydraulic interposing pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of pump efficiency based on leakage of hydraulic fluid without lengthening stroke of a plunger. SOLUTION: A diaphragm 31 performs a reciprocating deformation moving through hydraulic fluid based on the vertical movement of a plunger 49 associated with revolution of a cam 61, fuel is sucked from a suction passage 39 and fuel is discharged from a discharge passage 41. A cam follower 57 moving integrally with the plunger 49 is provided between the plunger 49 and the cam 61. Hydraulic fluid space 59 within the cam follower 57 and a hydraulic fluid chamber 37 are communicated by a communication path 65. In discharge stroke, a check valve 67 within the communication path 65 is opened and hydraulic fluid is accumulated in an accumulator 71. In suction stroke in which the plunger 49 rises, hydraulic fluid within the communication path 65 accumulated in the accumulator 71 is replenished in the hydraulic fluid chamber 37 and hydraulic fluid within a cam chamber 53 is replenished in hydraulic fluid space 59 via a through hole 57c provided on the cam follower 57.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic intervening pump for pumping a fluid by reciprocating a flexible member by hydraulic pressure.

[0002]

2. Description of the Related Art A fuel injection pump provided in an in-cylinder fuel injection type engine requires high-pressure fuel pumping as compared with an intake port injection type engine. In some cases, a partition wall of a flexible member such as the above is reciprocally deformed and moved by hydraulic pressure, thereby sucking and discharging fuel into and from a pump chamber.

FIG. 9 shows such a high-pressure fuel pump 2.
FIG. 1 is a system configuration diagram of a fuel supply system in which No. 01 is used.
The high-pressure fuel injection pump 201 described above is provided with a fuel feed pump 205 for sucking up the fuel in the fuel tank 203.
And a fuel injection valve 2 for injecting fuel to the engine 207
09 and a pressure accumulation chamber 211 connected to the pressure storage chamber 211. The fuel pressurized by the fuel injection pump 201 is sent to the pressure accumulation chamber 211, and is sent from the pressure accumulation chamber 211 to the fuel injection valve 209 of each cylinder. From fuel injection pump 201 to accumulator 2
Excess fuel sent to the fuel injection valve 209 via 11 is returned to the fuel tank 203 through the fuel return passage 213. The fuel return passage 213 includes a fuel injection valve 209.
Is provided with a pressure regulator 215 for adjusting the fuel pressure guided to the pressure to a predetermined value. The opening and closing operation of the fuel injection valve 209 is performed by the controller 217.

FIG. 10 shows an example of the above-described high-pressure fuel injection pump 201 (Japanese Patent Laid-Open No. 5-118279).
Reference). The inside of the pump body 1 is partitioned by a diaphragm 3 into a pump chamber 5 and a hydraulic oil chamber 7. The pump chamber 5 is provided with a suction passage 9 communicating with the fuel feed pump 205 side and a discharge passage 11 communicating with the fuel injection valve 209 side. The suction valve 13 that allows only the
Are provided with discharge valves 15 that allow only outflow of fuel from the pump chamber 5. A cylinder 17 is provided in communication with the hydraulic oil chamber 7, and a plunger 19 that can reciprocate vertically in the drawing is accommodated in the cylinder 17. On the hydraulic oil chamber 7 side of the diaphragm 3, a backup plate 21 for limiting the amount of deflection of the diaphragm 3 toward the hydraulic oil chamber 7 is provided. A plurality of through holes 21a are formed in the backup plate 21 so that the hydraulic pressure of the hydraulic oil chamber 7 can act on the diaphragm 3.

When the plunger 19 moves upward in the drawing, the diaphragm 3 is bent upward due to a decrease in the hydraulic pressure in the hydraulic oil chamber 7, whereby the pressure in the pump chamber 5 decreases and the suction valve 13 opens. The fuel is sucked into the pump chamber 5 through the suction passage 9. When the plunger 19 moves downward in the drawing, the diaphragm 3 bends downward due to an increase in the oil pressure in the hydraulic oil chamber 7, whereby the pressure in the pump chamber 5 increases, the discharge valve 15 opens, and the pump chamber 5 opens. The fuel inside is discharged through the discharge passage 11.

In the fuel discharge stroke due to the above-described lowering operation of the plunger 19, the hydraulic oil in the hydraulic oil chamber 7 leaks from the gap between the cylinder 17 and the plunger 19 due to the high pressure of the hydraulic oil chamber 7, and the pump efficiency decreases. Invite. For this reason, a hydraulic oil replenishment passage 23 for replenishing the leakage of the hydraulic oil is connected to the cylinder 17 near the limit position of the upward movement of the plunger 19 and communicates with the hydraulic oil chamber 7.

[0007]

However, in the above-mentioned conventional hydraulic intervening pump, the plunger 19 moves in the direction approaching the hydraulic oil chamber 7 to discharge fuel during the stroke.
Hydraulic oil supply passage 2 before being closed by plunger 19
From 3, the hydraulic oil partially flows backward, so that the stroke of the plunger 19 required to obtain a predetermined fuel discharge pressure increases, which causes an increase in the size of the fuel pump.

Accordingly, it is an object of the present invention to prevent a decrease in pump efficiency due to leakage of hydraulic oil without increasing the stroke of a plunger.

[0009]

According to a first aspect of the present invention, a pump body is divided into a pump chamber and a hydraulic oil chamber by a flexible member. While a suction passage through which the fluid is sucked and a discharge passage through which the fluid is discharged are connected, the hydraulic oil chamber is provided with a cylinder in which a plunger is reciprocally housed,
In a hydraulic intervening pump in which the pressurized fluid is sucked into a pump chamber from a suction passage and discharged from a discharge passage by the deformation movement of the flexible member based on the reciprocation of the plunger, the plunger reciprocates. A cam chamber accommodating a cam to be moved is filled with hydraulic oil, and a cam follower slidable in an outer cylinder provided around the cylinder is interposed between the plunger and the cam. And a hydraulic oil space that communicates with the hydraulic oil chamber via a communication path, and that communicates the hydraulic oil space with the cam chamber near the position where the plunger is farthest from the hydraulic oil chamber. A check valve that is provided with a replenishment passage and that allows the flow of hydraulic oil from the hydraulic oil space to the hydraulic oil chamber in the communication path; Hydraulic oil pressure generated by a compression operation of the cam follower with respect to the hydraulic oil space is accumulated in the communication path between the cam followers, and the accumulated hydraulic oil is supplied to the check valve based on the separation movement of the plunger from the hydraulic oil chamber. And an accumulator for supplying the hydraulic oil chamber to the hydraulic oil chamber via the air reservoir.

According to the hydraulic pump of the above construction, when the plunger moves in the direction approaching the hydraulic oil chamber together with the cam follower due to the rotation of the cam, the pressure in the hydraulic oil chamber increases, and the pressure of the flexible member increases. Due to the deformation movement to the pump chamber side, the pumping fluid in the pump chamber is discharged from the discharge passage. When the hydraulic oil supply passage enters the outer cylinder by the above movement of the cam follower, the pressure in the hydraulic oil space also increases, and the check valve on the hydraulic oil space side provided in the communication path opens, and the hydraulic pressure in the hydraulic oil space is reduced by the accumulator. And a predetermined pressure is accumulated in the accumulator. In the above-described discharge stroke, the hydraulic oil chamber is at a high pressure, so that the hydraulic oil leaks from the gap between the plunger and the cylinder into the hydraulic oil space.

When the plunger moves away from the hydraulic oil chamber together with the cam follower due to the rotation of the cam, the oil pressure in the hydraulic oil chamber decreases, and the flexible member deforms and moves toward the hydraulic oil chamber, thereby causing the pump chamber to move. Due to the pressure drop, the pumping fluid is sucked into the pump chamber through the suction passage. Due to the pressure drop of the hydraulic oil chamber due to the movement of the plunger, the check valve on the hydraulic oil chamber side provided in the communication path is opened, and the hydraulic oil in the communication path accumulated in the accumulator passes through the opened check valve and leaks through the check valve. Is supplied to the hydraulic oil chamber so as to replenish the hydraulic fluid, and the movement of the cam follower causes the hydraulic oil replenishment passage to communicate with the cam chamber filled with the hydraulic oil, passes through the hydraulic oil replenishment passage, and operates from the accumulator. The hydraulic oil containing the leakage supplied to the oil chamber is replenished to the hydraulic oil space.

According to a second aspect of the present invention, in the configuration of the first aspect, a pressure regulating valve for setting the pressure in the communication path lower than the pressure in the pump chamber is provided in a communication path between the two check valves. Was.

According to the above configuration, the pressure stored in the accumulator is limited to the pressure of the pump chamber or less by the operation of the pressure regulating valve. Therefore, after the hydraulic oil is replenished from the accumulator to the hydraulic oil chamber, the pressure in the communication passage is reduced. When the pressure becomes lower than the pressure in the hydraulic oil chamber, the check valve does not open, thereby preventing the flow of the hydraulic oil from the inside of the communication path after the replenishment of the hydraulic oil into the hydraulic oil chamber more than necessary.

According to a third aspect of the present invention, in the configuration of the first aspect of the present invention, the opening length in the reciprocating direction of the plunger and the cam follower is shorter than the reciprocating length of the plunger and the cam follower. The cam follower and the plunger are provided at positions such that a predetermined reciprocating movement length is obtained from a state in which the cam follower and the plunger are closest to the hydraulic oil chamber from a state in which the cam follower and the plunger are closed.

According to the above configuration, when the plunger and the cam follower move in a direction approaching the hydraulic oil chamber after the hydraulic oil is replenished from the hydraulic oil refill passage to the hydraulic oil space, the hydraulic oil refill passage enters the outer cylinder. Then, the movement is further continued, and a compression action is performed on the hydraulic oil chamber.

According to a fourth aspect of the present invention, in the configuration of the third aspect of the present invention, the hydraulic oil replenishment passage is arranged such that a required amount of replenishing hydraulic oil can flow in near a position where the plunger is farthest from the hydraulic oil chamber. It is formed at a position that opens to the cam chamber.

According to the above construction, when the plunger is located near the position farthest from the hydraulic oil chamber, the hydraulic oil supply passage provided in the cam follower opens to the cam chamber, whereby the required amount of hydraulic oil supply is increased. Flows into.

[0018]

According to the first aspect of the present invention, the plunger moves in the direction approaching the hydraulic oil chamber during the discharge stroke, and at this time, the communication path connected to the hydraulic oil chamber is not blocked by the plunger. Also, since the communication path is provided with a check valve that allows only the flow from the communication path to the hydraulic oil chamber,
Backflow of the hydraulic oil in the hydraulic oil chamber to the communication path does not occur, and the amount of hydraulic oil in the hydraulic oil chamber can be appropriately maintained, thereby increasing the stroke of the plunger to obtain a desired fuel discharge pressure. It is not necessary, and it is possible to avoid an increase in the size of the fuel pump.

According to the second aspect of the present invention, since the pressure regulating valve sets the pressure in the communication path lower than the pressure in the pump chamber, the pressure in the communication path after the hydraulic oil is replenished from the accumulator to the hydraulic oil chamber. Is lower than the pressure in the hydraulic oil chamber,
It is possible to avoid the flow of the hydraulic oil into the hydraulic oil chamber beyond the required amount from the communication path after the hydraulic oil is replenished, and it is possible to secure a desired amount of the hydraulic oil in the hydraulic oil chamber.

According to the third aspect of the present invention, the cam follower and the plunger can move in the direction closer to the hydraulic oil from the state where the hydraulic oil supply passage enters the outer cylinder and is closed, so that the hydraulic oil chamber Can be reliably performed.

According to the fourth aspect of the present invention, the hydraulic oil supply passage provided in the cam follower is provided in the cam chamber so that a required amount of hydraulic oil can flow near the position where the plunger is farthest from the hydraulic oil chamber. Because of the opening, the strokes of the plunger and the cam follower do not become unnecessarily large, and an increase in the size of the fuel pump is avoided.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view schematically showing a hydraulic intervening pump according to an embodiment of the present invention. The pump body 25 includes a body body 27 and a cover 29, and a diaphragm 31 as a flexible member is provided between the body body 27 and the cover 29 by a backup plate 33.
In addition, the outer peripheral edge is held. The backup plate 33 is provided on the body main body 27 side with respect to the diaphragm 31, and has a plurality of small holes 33a penetrating the front and back.

Since the diaphragm 33 is held between the body 27 and the cover 29, the pump chamber 35 to which the fuel (for example, gasoline) which is a pressurized fluid is supplied to the cover 29 is operated to the body 27. A working oil chamber 37 filled with oil is formed. The cover 29 is provided with a suction passage 39 for sucking fuel into the pump chamber 35 and a discharge passage 41 for discharging fuel from the pump chamber 35. A suction chamber 39 is provided with a pump chamber 35 from a feed pump for supplying fuel from a fuel tank (not shown).
Check valve 43 that allows only fuel to flow through
However, each of the discharge passages 41 is provided with a discharge check valve 45 that allows only the flow of fuel from the pump chamber 35 to a fuel injection valve (not shown). Here, the feed pressure of the feed pump is 0.3 MPa, and the supply pressure to the fuel injection valve is 10 MPa.

On the other hand, a hydraulic oil chamber 37 is
Is provided with a cylinder 47 whose lower end communicates with the cylinder 4.
The plunger 49 is slidably received in the upper end opening 7. Plunger 49 and backup plate 3
A return spring 51 for urging the plunger 49 upward is interposed between the return spring 51 and the spring 5.

Around the cylinder 47, the body main body 27
An outer cylinder 55 having an open upper end is formed in a cam chamber 53 formed in an upper portion of the cam cylinder 53. A cup-shaped cam follower 57 is slidably accommodated in the outer cylinder 55. The cam follower 57 is composed of a flat portion 57a with which the upper end of the plunger 49 contacts, and a cylindrical portion 57b projecting downward from the outer peripheral edge of the flat portion 57a, and at a position close to the flat portion 57a of the cylindrical portion 57b, A plurality of circular through holes 57c as hydraulic oil supply passages are provided in the circumferential direction. The cam follower 55, the plunger 49, and the body 27
A hydraulic oil space 59 is formed between the two.

The cam chamber 53 is filled with hydraulic oil and accommodates a cam 61 rotatably supported by a cam shaft 63 in contact with a cam follower 57 while being rotated by the rotation of an engine (not shown). ing. Cam 6
When the cam follower 57 is located at the uppermost position in FIG. 1 together with the plunger 49 by the rotation of FIG. 1 (hereinafter, this state is referred to as a top dead center), a part or all of the opening of the through hole 57c is provided. Opens into the cam chamber 53, and the cam chamber 5
The required amount of hydraulic oil is supplied to the hydraulic oil space 59 by the atmospheric pressure on the third side. The through hole 57c has a diameter of the plunger 49.
The cam follower 57, together with the plunger 49, is located at the lowermost position in FIG. 1 (hereinafter, referred to as “cam follower 57”). Until this state is called the bottom dead center), it is provided at a vertical position such that a predetermined stroke can be obtained.

The cylinder 47 and the outer cylinder 55 are connected to each other by a communication path 65. The opening position of the communication path 65 to the cylinder 47 is a position where the plunger 49 is not closed by the plunger 49 at the top dead center position, whereas the opening position of the communication path 65 to the outer cylinder 55 is such that the through hole 57c is It is set to a position where it is not closed by the cam follower 57 when it enters the inside and its opening is closed.

In the communication path 65, two check valves 67 and 69 set at the same valve opening pressure are arranged in series.
These check valves 67 and 69 allow only the flow of the hydraulic oil from the hydraulic oil space 59 to the hydraulic oil chamber 35. The communication path 65 between the check valves 67 and 69 is provided with an accumulator 71 for accumulating the operating oil pressure, and is connected to an oil release path 73 for releasing excess operating oil in the communication path 65 to the cam chamber 53. ing. Oil release passage 73
Is provided with a pressure regulating valve 75 that allows only the flow of hydraulic oil from the communication path 65 to the cam chamber 53.

The opening pressure of the pressure regulating valve 75 is determined by the check valve 67,
The fuel feed pressure in the pump chamber 35 is set higher than the valve opening pressure of 69 and is 0.22M lower than 0.3 MPa.
Pa is set. The accumulator 71 is provided with the pressure regulating valve 7.
A working oil pressure of 0.22 MPa equivalent to the adjustment pressure of No. 5 is accumulated.

Next, the operation of the above-described hydraulic intervening pump will be described. When the engine is started and the cam 61 rotates, the plunger 49 and the cam follower 57 reciprocate up and down integrally with the rotation. In the state shown in FIG. 1, the plunger 49 and the cam follower 57
When the cam 61 is rotated from this state at the top dead center position, the plunger 49 and the cam follower 57 move downward against the return spring 51, and enter a fuel discharge stroke.

In the discharge stroke, the pressure of the hydraulic oil chamber 37 increases due to the downward movement of the plunger 49, and the deformation movement of the diaphragm 31 toward the pump 35 chamber causes the fuel in the pump chamber 35 to discharge. The check valve 45 is opened to be discharged from the discharge passage 41. On the other hand, when the through hole 57c enters the outer cylinder 55 due to the downward movement of the cam follower 57, the pressure in the hydraulic oil space 59 increases, the check valve 67 in the communication path 65 opens, and the operation of the hydraulic oil space 59 is activated. The hydraulic pressure acts on the accumulator 71,
A predetermined pressure is accumulated in the accumulator 71. Excess hydraulic oil in the communication path 65 at this time is released from the oil release passage 73 to the cam chamber 53 by opening the pressure regulating valve 75.
In the discharge stroke, the hydraulic oil in the hydraulic oil chamber 37 which has a high pressure leaks from the gap between the plunger 49 and the cylinder 47 into the hydraulic oil space 59.

The cam 61 rotates 90 degrees from the state shown in FIG.
When the plunger 49 and the cam follower 57 reach the bottom dead center, the discharge stroke ends, and when the cam 61 further rotates, the process shifts to the suction stroke. In the suction stroke, the plunger 49 and the cam follower 57 move upward by being pushed by the return spring 51, the hydraulic pressure in the hydraulic oil chamber 37 decreases, and the diaphragm 31 deforms and moves to the hydraulic oil chamber 37 side. The suction check valve 43 opens due to the pressure drop in the pump chamber 35, and fuel is sucked into the pump chamber 35 through the suction passage 39.

When the pressure of the hydraulic oil chamber 37 decreases due to the movement of the plunger 49, the hydraulic oil in the communication path 67 accumulated by the accumulator 71 causes the check valve 69 to open, thereby causing the plunger 49 to communicate with the cylinder 47. An amount corresponding to the amount of hydraulic oil leaking from the gap is refilled into the hydraulic oil chamber 37. At the same time, the movement of the cam follower 57 causes the through hole 57 c to communicate with the cam chamber 53, and the cam follower 57 includes the leakage supplied from the accumulator 71 to the hydraulic oil chamber 37 through the through hole 57 c. The amount of hydraulic oil corresponding to the amount supplied to the communication path 65 is replenished to the hydraulic oil space 59.

In the above-described suction stroke, the pressure in the communication path 65 is lowered by the action of the pressure regulating valve 75 below the pressure in the hydraulic oil chamber 37 equivalent to the pump chamber 35, and the check valve 69 is not opened. The inflow of hydraulic oil from the communication path 65 to the hydraulic oil chamber 37 later is avoided, and the amount of hydraulic oil in the hydraulic oil chamber 65 is appropriately secured.

At the beginning of the discharge stroke, the communication path 65 is open to the hydraulic oil chamber 37. However, since the check valve 69 is closed due to the high pressure of the hydraulic oil chamber 37, the hydraulic oil chamber 37 is closed.
Backflow of the working oil in the inside to the communication path 65 does not occur, and the pump function by the lowering operation of the plunger 49 is normally exhibited. For this reason, it is not necessary to lengthen the stroke of the plunger 49, and an increase in the size of the fuel injection pump is avoided.

FIG. 2 shows the stroke positions of the plunger 49 and the cam follower 57 equivalent to each other with respect to the time change accompanying the rotation of the cam 61. The stroke from the top dead center to the bottom dead center is the discharge stroke. A, and the stroke from the bottom dead center to the top dead center is indicated by B as the suction stroke. At time t ₁ immediately before the top dead center at the end of the suction stroke B, replenishment of the hydraulic oil accumulated by the accumulator 71 to the hydraulic oil chamber 37 is started. This replenishment is performed at the top dead center after the end of the suction stroke B. It made up to the time t ₃ when the corresponding. This replacement section
It is shown by C _1.

At a time t ₂ immediately after the time t ₁ at which replenishment of the hydraulic oil into the hydraulic oil chamber 37 is started, the through hole 57 c of the cam follower 57 is exposed from the outer cylinder 55, and the hydraulic oil in the cam chamber 53 is There supplemented to operating oil chamber 59 through the through-hole 57c, the replenishment is carried out until the initial time t ₄ of the discharge stroke a exceeds the top dead center. The replenishment section are indicated by C _2.

FIG. 3 is a front sectional view showing a more specific structure of the above-described hydraulic intervening pump, and FIG. 4 is a side sectional view of the same. Here, the same reference numerals are given to the components corresponding to the components shown in FIG. Here, the diaphragm 3 in FIG.
1 instead of a cylindrical bellows 7 which can be expanded and contracted up and down in the figure.
7 is used. The upper end of the bellows 77 is the body 2
The lower end of the bellows 77 is fixed to the periphery of a disk-shaped end plate 81, and the pump body 25 is pumped by the end plate 81 and the bellows 77. It is partitioned into a chamber 35 and a hydraulic oil chamber 37.

The cylinder 47 is formed at the upper end of a cylinder member 83 screwed to the main body 27.
The lower end of the return spring 51 that urges the plunger 49 that slides in the cylinder 47 upward is supported by a spring receiver 85 fixed to a lower portion of the cylinder member 83. The boss member 79 is provided on the outer periphery of the cylinder member 83.
Are fitted.

A communication path 65 connecting the hydraulic oil chamber 37 and the hydraulic oil space 59 is provided with a communication hole 83 formed in the cylinder member 83.
a through a communication oil hole 37d formed in the cylindrical portion 57b of the cam follower 57.
Is in communication with

FIG. 5 is a sectional view showing the detailed structure of the accumulator 71. The accumulator 71 is screw-connected from the side of the body 27 and has a housing 8 provided with a spring chamber 87a having an open right end in the drawing.
7 and a sheet member 89 fixed to the body 27 at a position corresponding to the communication path 65 at the distal end of the housing 87.
And a spool 91 housed in the spring chamber 87a so as to be movable in the left-right direction in the figure, and a spring 93 housed in the spring chamber 87a and biasing the spool 91 toward the sheet member 89. .

The sheet member 89 includes the accumulator 71
The housing 87 is provided with a small hole 87b which connects the spring chamber 87a and the passage 95 which communicates with the oil release passage 73. In the passage 95, the spool 9
Hydraulic oil leaks through the gap between the housing 1 and the housing 87.

As shown in FIG. 6A, when the spool 91 is pressed by the spring 93 and is in contact with the sheet member 89, the pressure in the communication path 65 is lower than 0.20 MPa. In this state, the process proceeds to the discharge stroke, and when the pressure in the communication path 65 increases, the spool 91 moves to the left as shown in FIG. Due to the operation of the pressure regulating valve 75, the pressure is set to 0.
When the pressure reaches 22 MPa, the operation is stopped. The amount of change in volume due to the movement distance S is the maximum replenishment amount of hydraulic oil to the hydraulic oil chamber 37 by the accumulator 71.

FIG. 7 is a sectional view showing the detailed structure of the pressure regulating valve 75. The pressure regulating valve 75 is screw-connected from the side of the body main body 27, and has a housing 97 having a spring chamber 97a having an open right end in the drawing, and a housing 97.
Member 9 fixed to body 27 at the tip of
9 and a relief valve 101 housed in the spring chamber 97a of the housing 97 so as to be movable in the left-right direction in the figure.
And the relief valve 1 housed in the spring chamber 97a.
Spring 10 for urging 01 toward seat member 99
And 3.

The housing 97 includes a relief valve 10
1 is in contact with the sheet member 99 and the oil release passage 73
A small hole 97b communicating with the spring chamber 97a is formed. From the state of FIG. 7, the pressure in the communication path 65 is equal to the set load of the spring 103 (here, 0.22 MPa).
, The relief valve 101 as shown in FIG.
Moves to the front of the small hole 97b while pressing the spring 103, and the communication path 65 and the oil release passage 73 are separated by the small hole 97b.
The excess hydraulic oil in the communication path 65 is released to the oil release passage 73.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a hydraulic intervening pump showing one embodiment of the present invention.

FIG. 2 shows the stroke positions of the plunger and the cam follower in the hydraulic intervening pump of FIG.
FIG. 4 is an explanatory diagram corresponding to a time change with rotation of a cam.

FIG. 3 is a front sectional view showing a more specific configuration of the hydraulic intervention type pump in FIG. 1;

FIG. 4 is a side sectional view showing a more specific configuration of the hydraulic intervention pump in FIG. 1;

FIG. 5 is a sectional view showing a detailed structure of an accumulator used in the hydraulic intervening pump in FIG.

FIG. 6 is an explanatory diagram of the operation of the accumulator of FIG. 5;
(A) shows a state where pressure is not accumulated, and (b) shows a state where pressure is accumulated.

FIG. 7 is a sectional view showing a detailed structure of a pressure regulating valve used in the hydraulic intervening pump in FIG.

FIG. 8 is an operation explanatory view of the pressure regulating valve of FIG. 7;

FIG. 9 is a system configuration diagram of a fuel supply system using a high-pressure fuel pump provided in the in-cylinder fuel injection engine.

FIG. 10 is a cross-sectional view of a main part of a hydraulic intervening pump showing a conventional example.

[Explanation of symbols]

 25 Pump body 31 Diaphragm (flexible member) 35 Pump chamber 37 Hydraulic oil chamber 39 Suction passage 41 Discharge passage 47 Cylinder 49 Plunger 53 Cam chamber 55 Outer cylinder 57 Cam follower 57c Through hole (hydraulic oil refill passage) 59 Hydraulic oil space 61 Cam 65 Communication path 67, 69 Check valve 71 Accumulator 75 Pressure regulating valve 77 Bellows (flexible member)

Claims (4)

[Claims] A pump body is divided into a pump chamber and a hydraulic oil chamber by a flexible member, and the pump chamber is connected to a suction passage through which a pumping fluid is sucked and a discharge passage through which the fluid is discharged. On the other hand, a cylinder in which the plunger is reciprocally accommodated is provided in the hydraulic oil chamber, and the pressure-feeding fluid is supplied to the pump chamber by the deformation movement of the flexible member based on the reciprocation of the plunger. In a hydraulic intervening pump that sucks in from a suction passage and discharges from a discharge passage, hydraulic fluid is filled in a cam chamber in which a cam for reciprocating the plunger is housed, and the cylinder is provided between the plunger and the cam. A cam follower slidable in an outer cylinder provided around the
A hydraulic oil space communicating with the hydraulic oil chamber is formed between the plunger and the hydraulic oil chamber via a communication path, and the plunger communicates the hydraulic oil space with the cam chamber near a position farthest from the hydraulic oil chamber. A hydraulic oil replenishment passage is provided, and two check valves that allow the flow of hydraulic oil from the hydraulic oil space to the hydraulic oil chamber are provided in series on the communication path, and the communication path between the two check valves is provided in the communication path. The operating oil pressure generated by the compression operation of the cam follower with respect to the operating oil space is accumulated, and the accumulated operating oil is transferred to the operating oil chamber via the check valve based on the movement of the plunger away from the operating oil chamber. A hydraulic intervening pump provided with an accumulator for supplying. 2. A hydraulic intervening pump according to claim 1, wherein a pressure regulating valve for adjusting a pressure in the communication path is provided in a communication path between the two check valves. 3. The hydraulic oil replenishing passage is formed such that an opening length of the plunger and the cam follower in the reciprocating direction is shorter than a reciprocating length of the plunger and the cam follower, and the hydraulic oil replenishing passage enters the outer cylinder and is closed. 2. The hydraulic pump according to claim 1, wherein the cam follower and the plunger are provided at positions where a predetermined reciprocating movement length is obtained until the cam follower and the plunger are closest to the hydraulic oil chamber. 4. The hydraulic oil replenishment passage is formed at a position where the plunger is farthest from the hydraulic oil chamber and at a position that opens to the cam chamber so that a required amount of replenishing hydraulic oil can flow therein. The hydraulically-assisted pump according to claim 3.