JP2000310183A - Plunger type pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger type pump whose pump compression rate is large and self suction force and air discharge ability are improved by reducing the volume of a pump chamber. SOLUTION: In a plunger type pump wherein a liquid suction passage 3c with bottom is provided in a plunger 3 sliding to the inner wall of a cylinder 2, a pump chamber 14 near the releasing end of the liquid suction passage 3c and a suction valve 8 to open and close the communication passage between the liquid suction passage 3c and the pump chamber 9 and a discharge valve 9 to open and close the communication passage between the pump chamber 14 and a discharge port 13b, a pin 4, which is inserted into a long hole 3a which is long in the axial direction and provided in the plunger 3, is supported by the cylinder 2, and the plunger 3 is pressed against a pump driving cam 24 by the spring 5 intervening between the pin 4 and the bottom of the liquid suction passage 3c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type pump, and more particularly to a plunger type pump having a large pump compression ratio and high self-priming force and air discharging ability.

[0002]

2. Description of the Related Art A plunger type pump is conventionally known as a pump capable of obtaining a high discharge pressure. In recent years, as one of the measures against engine exhaust gas, in-cylinder injection (Direct Injection) that injects fuel directly into the engine cylinder
However, in this case, the discharge pressure of the fuel pump generally needs to be 500 kPa or more, and a plunger type pump is used.

[0003] In the plunger type pump proposed in JP-A-10-30575 and JP-A-10-30576, a spring (return spring) for pressing the plunger against the pump driving cam is provided between the suction valve and the discharge valve. It is located in the pump room, which is a space.

The return spring requires a large operating force to drive the plunger, and has a long compression length. For this reason, the capacity of the pump chamber is increased, and the compression ratio is reduced. When the compression ratio is small, there is a problem that the self-priming force and the air discharging ability are reduced. In addition, there is a problem that the assembling is performed in a state where the plunger and the return spring are separated from each other, so that it is difficult to assemble.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to reduce the volume of the pump chamber to increase the pump compression ratio, thereby increasing the self-priming force and air. An object of the present invention is to provide a plunger pump having a high discharge capacity.

Another object of the present invention is to provide a plunger type pump which is easy to assemble by assembling a plunger and a return spring into a pump body while being assembled to a cylinder.

[0007]

According to the plunger type pump of the present invention, a bottomed liquid suction passage is provided in a plunger sliding with the inner wall of a cylinder, and a pump chamber is provided near an open end of the liquid suction passage. A plunger-type pump provided with a suction valve for opening and closing between the liquid suction passage and the pump chamber and a discharge valve for opening and closing between the pump chamber and a discharge port, wherein the plunger has a long axial length. A pin inserted into the hole is supported by the cylinder, and the plunger is pressed against the pump driving cam by a spring interposed between the pin and the bottom of the liquid suction passage.

In the plunger type pump,
The suction valve may be a flat valve that is pressed into contact with an end surface of an open end of a liquid suction passage of the plunger.

In each of the plunger pumps, a cylinder chamber surrounded by the cylinder inner wall and a cam chamber for accommodating the pump driving cam are separated by an elastic seal member, and the cam chamber is a suction port of a separate lubricating oil pump. It is arranged on the road.

Further, in the plunger type pump, the cam chamber is arranged below the oil tank, and an air vent is provided at an upper part of the cam chamber.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel pump according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a plunger type fuel pump according to an embodiment of the present invention.
(A) is a suction flat valve 8 of the plunger type fuel pump.
And an enlarged sectional view showing the discharge flat valve 9 and its vicinity,
FIG. 2B is a plan view of the suction flat valve and the discharge flat valve as viewed from above, and FIG. 3 is a sectional view taken along line AA in FIG.

A pump body 1 shown in the figure has a vertical cylinder housing hole 1a for housing a plug 13 and a cylinder 2.
And a cam chamber 27 for accommodating the drive shaft 22 are formed in communication with each other. The lower end surface of the cylinder 2 abuts the stepped portion of the cylinder housing hole 1a, and the valve seat 10 and the valve case 11 are formed by the upper end surface of the cylinder 2 and the plug 13 screwed into the pump body 1 by screwing the screw 13a. It is pinched.

A cylindrical plunger 3 with a bottom is slidably fitted on the inner peripheral surface of the cylinder 2. Diaphragm 16
Is a presser member 1 into which a small diameter portion of the plunger 3 is press-fitted.
7 and the plunger 3, and the outer periphery of the diaphragm 16 is held between the cylinder 2 and the pump body 1. The diaphragm 16 partitions the space between the cylinder housing hole 1a and the cam chamber 27.

The pin 4 inserted into the radial hole of the cylinder 2 also passes through the elongated hole 3a of the plunger 3 and enters the suction passage 3c formed at the center of the plunger 3. A compression coil spring 5 fitted between the pin 4 and the bottom surface of the plunger 3 presses the lower end of the small diameter portion of the plunger 3 against the bearing 24. The bearings 23, 23 fitted to the pump body 1 and the pump body cover 20, respectively, rotatably support the drive shaft 22, and the bearing 24 fitted to the eccentric portion 22a of the drive shaft 22 constitutes an eccentric cam. I have.

The drive shaft 22 is rotationally driven by a shaft driven by an engine via a coupling 26. The pump body cover 20 is fastened to the pump body 1 by a countersunk screw 21, and an O-ring 31 is sandwiched between the pump body 1 and the pump body 1 to close the cam chamber 27. An oil seal 25 is provided between the pump body cover 20 and the drive shaft 22.
Sealed with.

A nipple 28 and a nipple 29 are press-fitted into the pump body 1.
The nipple 29 is connected to an oil tank (not shown) arranged at a higher position, and is connected to the suction side of a separate lubricating oil pump. As described above, the cam chamber 27 serves as a suction passage of a separate lubricating oil pump (not shown), but an air vent closed by the screw 30 is provided above the cam chamber 27 as shown in FIG. That is, the air in the cam chamber 27 can be removed by removing the screw 30.

A suction port 1b formed in the pump body 1 communicates with an inflow passage 2a of the cylinder 2, and the inflow passage 2a communicates with an inflow groove 2b provided on the inner periphery of the cylinder 2. The inflow groove 2b is always in communication with the suction passage 3c of the plunger 3 via an inflow hole 3b formed in the plunger 3. The inflow path 2a also communicates with the upper space of the diaphragm 16 so that it can cope with a change in volume due to the vertical movement of the diaphragm 16. In addition, the inflow path 2a and the suction port 1
Positioning with b is performed by a positioning unit (not shown).

As shown in detail in FIG.
A suction flat valve 8 is disposed between the plunger 3 and the plunger 3, and is urged by a compression coil spring 6 so as to be pressed against the upper end surface of the plunger 3. Also, valve seat 1
The discharge flat valve 9 is disposed between the valve case 11 and the valve case 11, and is urged to be pressed against the upper surface of the valve seat 10 by the compression coil spring 7 disposed between the discharge flat valve 9 and the valve case plug 12.

The intake flat valve 8 and the discharge flat valve 9 have the same shape, and FIG. 2A shows a side view. As shown in FIG. 2B, the suction flat valve 8 and the discharge flat valve 9 have a cross-shaped large diameter portion 8 for positioning.
a, 9a, between which a small diameter portion 8b forming a flow path,
9b.

The space between the suction flat valve 8 and the discharge flat valve 9 which opens and closes in accordance with the reciprocation of the plunger 3 forms a pump chamber 14, and the downstream side of the discharge flat valve 9 is connected to the valve case plugs 12 and 13. The formed hole communicates with the discharge hole 13b. The pump chamber 14 is sealed to the outside by an O-ring 15 interposed between the valve case 1 and the plug 13.

The fuel can be supplied to the engine by connecting the suction port 1b of the fuel pump thus formed to a fuel tank (not shown) and connecting the discharge hole 13b to a fuel distribution pipe (not shown) of the engine. That is, in the suction stroke in which the plunger 3 descends, the suction flat valve 8 also descends following the plunger 3, but when the negative pressure in the pump chamber 14 increases, the suction flat valve 8 and the plunger 3
A gap is provided for the fuel to flow between them, and the increased volume of the pump chamber 14 is filled with the fuel. During this time, the discharge flat valve 9 applies a force due to the pressure difference between the pump chamber 14 and the discharge hole 13b to the elasticity of the compression coil spring 7 so that the valve seat 1
It is pressed against zero and the flow path is closed.

In the discharge stroke in which the plunger 3 rises, the suction flat valve 8 is pressed against the plunger 3 to close the flow passage and reduce the volume of the pump chamber 14. The pressure in the pump chamber 14 increases, the discharge flat valve 9 is lifted up against the elasticity of the compression coil spring 7, and the discharge flat valve 9 is opened. Then, the fuel in the pump chamber 14 is discharged from the discharge holes 13b.

In the fuel pump constructed as described above, the compression coil spring 5 (return spring) for returning the plunger which requires a large elasticity and a height during compression is provided in the pump chamber 14.
Since it is not inside, the minimum volume (dead space) of the pump chamber 14 can be reduced, the compression ratio can be increased, and the self-priming force and the air discharging ability can be increased.

The diameter of the plunger 3 cannot be reduced so much because the compression coil spring 5 for returning the plunger is in the suction passage 3c of the plunger 3. However, since the suction flat valve 8 having a short height is used, the pump chamber 14 is not used. Can be made even smaller than when a ball valve is used.
Further, the compression coil spring 5 is connected to the suction passage 3c of the plunger 3.
Since the pump is internally disposed, the height of the pump can be reduced and the pump can be downsized. As shown in the embodiment, if the discharge valve is also a flat valve, the overall height of the pump can be reduced.

Further, the compression coil spring 5, the pin 4, the plunger 3 and the cylinder 2 can be sub-assembled into the pump body 1 with the compression coil spring 5 interposed between the pin 4 and the bottom surface of the plunger 3. The assembling work becomes easier than when these are assembled in a separated state. Pin 4 is connected to plunger 3 and cylinder 2
, The plunger 3 is prevented from rotating, and the torsional deformation of the diaphragm 16 is prevented.

Further, since the cam chamber 27 is disposed on the suction side of the separate lubricating oil pump, the driving section of the plunger 3 is sufficiently lubricated. Since the cam chamber 27 is provided with an air vent, it is easy to release air from the suction passage of the separated lubricating oil pump.

FIG. 4 is a partial sectional view showing a plunger type fuel pump according to a second embodiment of the present invention. In this example, the sealing function of the diaphragm 16 in the first embodiment is set to O.
Rings 32 and 33 are substituted. That is, the O-ring 33 sandwiched between the pump body 1 and the cylinder 2 seals the gap between the cam chamber 27 and the gap between the pump body 1 and the cylinder 2, and the O-ring 32 is formed between the cam chamber 27, the plunger 3 and the cylinder. Seal with the gap of 2. Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted. By using the O-ring instead of the diaphragm, the manufacturing cost can be reduced.

As an embodiment, a case has been described in which the present invention is applied to a fuel pump of an engine. However, the present invention can also be applied to a pump for sending water, oil, or the like at a relatively high pressure.

[0029]

According to the plunger type pump of the present invention,
Since there is no compression coil spring for returning the plunger in the pump chamber, the minimum volume (dead space) of the pump chamber can be reduced, the compression ratio can be increased, and the self-priming force and the air discharging ability can be increased. Since the suction flat valve is used, the volume of the pump chamber can be reduced as compared with the case where a spherical valve is used. Further, since the compression coil spring is arranged in the suction passage of the plunger, the height of the pump can be reduced, and the pump can be downsized.

Further, since the compression coil spring for return of the plunger, the plunger and the cylinder can be sub-assembled and incorporated into the pump body, the assembling work becomes easier than when these are incorporated in a separated state. Further, since the pin is inserted through the hole of the plunger and the cylinder, the plunger is prevented from rotating, and the torsional deformation of the elastic seal member separating the cylinder chamber and the cam chamber is prevented.

Further, since the cam chamber is arranged on the suction side of the separate lubricating oil pump, lubrication of the plunger driving section is sufficiently performed. Since the air vent is provided in the cam chamber, it is easy to release air from the suction passage of the separated lubricating oil pump.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plunger type fuel pump according to a first embodiment of the present invention.

FIG. 2A is an enlarged sectional view showing a suction valve and a discharge valve of the plunger type fuel pump and the vicinity thereof;
(B) is the top view which looked at the suction valve and the discharge valve from the upper part.

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

FIG. 4 is a partial sectional view showing a plunger type fuel pump according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pump body, 1a cylinder accommodation hole, 1b suction port 2 cylinder, 2a inflow passage, 2b inflow groove 3 plunger, 3a long hole, 3b inflow hole, 3c suction passage 4 pins 5, 6, 7 Compression coil spring 8 Suction flat valve , 8a large diameter part, 8b small diameter part 9 discharge flat valve, 9a large diameter part, 9b small diameter part 10 valve seat 11 valve case 12 valve case plug 13 plug, 13a screw, 13b discharge hole 14 pump chamber 15 O-ring 16 diaphragm 17 Pressing member 20 Pump body cover 21 Countersunk screw 22 Drive shaft, 22a Eccentric part 23, 24 Bearing 25 Oil seal 26 Coupling 27 Cam chamber 28, 29 Nipple 30 Screw 31, 32, 33 O-ring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Saito 309 Toizawa, Takizawa-mura, Takizawa-mura, Iwate-gun Inside Mikniadec Co., Ltd. (72) Ryo Shichi 309-outer Toyama, Takizawa-mura, Iwate-gun F term (reference) in the company Mikniadeck 3H070 AA02 BB02 BB07 CC04 CC22 CC37 DD17 DD35 DD66 3H071 AA07 BB01 CC24 CC47 DD03 DD42 3H075 AA03 BB03 BB13 CC01 CC40 DA09 DB03 DB24

Claims (4)

[Claims] 1. A bottomed liquid suction passage is provided in a plunger sliding with an inner wall of a cylinder, a pump chamber is provided near an open end of the liquid suction passage, and a pump chamber is provided between the liquid suction passage and the pump chamber. In a plunger type pump provided with a suction valve that opens and closes and a discharge valve that opens and closes between the pump chamber and a discharge hole, a pin that passes through a long hole in the axial direction provided in the plunger is supported by the cylinder, A plunger type pump wherein the plunger is pressed against a pump driving cam by a spring interposed between a pin and a bottom of the liquid suction passage. 2. The flat valve which is pressed against an end face of an open end of a liquid suction passage of the plunger.
Plunger pump. 3. A cylinder chamber surrounded by an inner wall of the cylinder and a cam chamber containing the pump drive cam are separated by an elastic seal member, and the cam chamber is arranged in a suction passage of a separate lubricating oil pump. Item 2. A plunger type pump according to item 1 or 2. 4. The plunger type pump according to claim 3, wherein said cam chamber is disposed below an oil tank, and an air vent is provided above said cam chamber.