JP2001020832A - Plunger fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger fuel pump reducing pulse width. SOLUTION: In a multi-plunger pump for confluence of discharge flow in a plunger pump comprising plungers 3 radially equally spaced relative to a cam 24 for driving the plungers 3, a pump body 1 is integrally provided with a pressure regulator 33 in a position of equal distance and equal passage volume from each discharge valve of the plunger type pump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plunger type fuel pump, and more particularly to a plunger type fuel pump having a reduced pulsation width.

[0002]

2. Description of the Related Art A plunger type pump is conventionally known as a pump capable of obtaining a high discharge pressure. The discharge flow rate waveform per plunger of the plunger type pump becomes a half-wave sine waveform in one reciprocation of the plunger. Generally, a plunger type pump has large pulsation, and means for reducing the pulsation is disclosed in Japanese Patent Application Laid-Open No. 10-18960.

In the plunger type pump proposed in Japanese Patent Application Laid-Open No. 10-18960, plungers are arranged at equal intervals in a radial direction with respect to a cam for driving the plunger, and a discharge flow path of the plunger type pump formed by each plunger. It communicates with a pressure chamber, and a discharge port is provided in this pressure chamber. However, this discharge port is not arranged at a position equidistant from the discharge valve of each plunger type pump.

Further, in recent years, direct injection (Direct Injection) in which fuel is directly injected into an engine cylinder is often used as one of the measures against engine exhaust gas. However, in a two-cycle engine, the discharge pressure of a fuel pump is generally low. 50
0 kPa to 600 kPa is required, and a plunger type pump is used. In this case, a pressure regulator is used to suppress fluctuations in pressure.

When the plunger type pump proposed in Japanese Patent Application Laid-Open No. 10-18960 is used as a fuel pump for supplying fuel to an engine by direct injection, a pressure regulator is disposed in a fuel flow path downstream of a discharge port. However, the position of the pressure regulator is not equidistant from the discharge valve of each plunger type pump. If the position of the pressure regulator is not equidistant from the discharge valve of each plunger pump, the pressure wave based on the compressibility of fuel and the inertia due to mass is disturbed, and the pulsating flow and pulsating pressure cannot be reduced sufficiently.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a plunger type fuel pump capable of sufficiently reducing a pulsating flow and a pulsating pressure. To provide.

[0007]

In the plunger type fuel pump of the present invention, the plungers are arranged at regular intervals in the radial direction with respect to a cam for driving the plunger, and the discharge flow of the plunger type pump formed by each plunger is controlled. In a multi-plunger pump to be joined, a pressure regulator is provided integrally with a pump body at a position equidistant from the discharge valve of each of the plunger pumps and at a position of an equal flow volume.

Further, in the plunger type fuel pump, the pressure regulator is a diaphragm type pressure regulator.

[0009]

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 side view showing a plunger type fuel pump according to an embodiment of the present invention, FIG. 2 is a rear view showing the plunger type fuel pump, FIG. 3 is a sectional view taken along the line AA in FIG. 5A is an enlarged sectional view of a portion C in FIG. 4, and FIG.
FIG. 5B is an enlarged plan view of the suction valve 8 shown in FIG.

A pump body 1 shown in FIG. 1 has three radially arranged three-pieces which accommodate a plug 13 and a cylinder 2.
Each of the cylinder housing holes 1a and the cam chamber 27 that houses the drive shaft 22 are formed in a state where they communicate 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
The center of the cap is a cap 1 into which the lower end of the plunger 3 is pressed.
7, the outer periphery of the diaphragm 16 is clamped between the cylinder 2 and the pump body 1. The diaphragm 16 partitions a space between the cylinder housing hole 1a and the cam chamber 27.

The pin 4 inserted through 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. The compression coil spring 5 fitted between the pin 4 and the bottom surface of the plunger 3 is a cap 1 into which the plunger 3 is pressed.
7 is pressed against the bearing 24. Pump body 1 and bearing 2 supported by pump body cover 20
Reference numerals 3 and 23 rotatably support the drive shaft 22, and a bearing 24 fitted to an eccentric portion of the drive shaft 22 forms an eccentric cam.

The drive shaft 22 is driven to rotate by the engine. The pump body cover 20 is fastened to the pump body 1 by a countersunk screw 21, and an O-ring 30 is sandwiched between the pump body 1 and the pump body 1 to close the cam chamber 27. The space between the pump body cover 20 and the drive shaft 22 is sealed by an oil seal 25.

A nipple 28 and a nipple 29 are press-fitted into the pump body 1, and the nipple 28 is
The nipple 29 is connected to the suction side of the separate lubricating oil pump, communicating with an oil tank disposed above.
The cam chamber 27 becomes a part of the engine lubricating oil passage.

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 passage 2a also communicates with the upper space of the diaphragm 16 so that it can cope with a volume change 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. 5A, a flat suction valve 8 is disposed between the valve seat 10 and the plunger 3 and is urged by the compression coil spring 6 so as to be pressed against the end face of the plunger 3. I have. Also, valve seat 1
The discharge flat valve 9 is disposed between the valve case 11 and the valve case 11, and the compression coil spring 7 disposed between the discharge flat valve 9 and the valve case 11 is pressed against the surface of the valve seat 10 (the lower surface in FIG. 5A). Have been biased to be.

The suction flat valve 8 and the discharge flat valve 9 have similar shapes, and FIG. 5A shows a side view. FIG. 5B is a plan view showing a state where the suction flat valve 8 shown in FIG.
The discharge flat valve 9 has a cross-shaped large-diameter portion for positioning, and a small-diameter portion forming a flow path therebetween.

A space between the suction flat valve 8 and the discharge flat valve 9 which opens and closes in accordance with the reciprocating motion of the plunger 3 forms a pump chamber 14, and a downstream side of the discharge flat valve 9 has a hole provided in the valve case 11. Valve case 11
The pump body 1 is in communication with a discharge passage 1 c provided in the pump body 1 through a gap between the pump body 1 and the plug 13. Also, the pump chamber 14
Is an O interposed between the pump body 1 and the plug 13.
It is sealed to the outside by a ring 15.

The discharge passages 1c having the same shape for each pump chamber 14 are provided at equal intervals, and communicate with a pressure chamber 34 of a pressure regulator 33 disposed on the center axis of the drive shaft 22. Pressure regulator 3
Numeral 3 is arranged in the space between the pump body 1 and the pressure regulator cover 35 fastened to the pump body 1 by screws 41, and includes a diaphragm 36, a diaphragm holding member 37, compression coil springs 38 and 39, and a ball 40. ing.

The diaphragm 36 divides the pressure chamber 34 and the concave space of the pressure regulator cover 35. The compression coil spring 38 presses the diaphragm holding member 37 against the ball 40. The compression coil spring 39 presses the ball 40 against the diaphragm holding member 37. When the pressure in the pressure chamber 34 is low, the ball 40 closes the passage from the pressure chamber 34 to the return outlet 1e. The pressure chamber 34
Is always in communication with the pump outlet 1d. Discharge path 1c,
When fuel of a flow rate within a predetermined range is sent from 1c.

The fuel can be supplied to the engine by connecting the suction port 1b of the fuel pump formed as described above to the fuel tank and connecting the pump discharge port 1d to the fuel distribution of the engine. That is, in the suction stroke in which the plunger 3 descends (stroke moving in the direction of the bearing 24), 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 A gap is provided between the plungers 3 to allow the fuel to flow, and the increased volume of the pump chamber 14 is filled with the fuel. During this time, the discharge flat valve 9 is pressed against the valve seat 10 by applying a force due to the pressure difference between the pump chamber 14 and the discharge passage 1c to the elasticity of the compression coil spring 7, thereby closing the flow passage.

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 path 1c.

Each flow rate discharged by the three plungers 3 is 1
It is the same sine wave half-wave waveform having a phase difference of 20 °, and the pulsation width of the combined flow rate is small, but the flow from each discharge flat valve to the pressure chamber 34 of the pressure regulator 33 as in this embodiment is When the shape and shape of the passage are the same, the pressure wave based on the inertia due to the compressibility and mass of the fuel is not disturbed, and the pulsating flow and the pulsating pressure can be sufficiently reduced.

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

[0025]

According to the plunger type fuel pump of the present invention, since the shape and dimensions of the flow passages from each discharge valve to the pressure regulator are the same, the pressure wave based on the compressibility of fuel and inertia due to mass is not disturbed. Therefore, the pulsating flow and the pulsating pressure can be sufficiently reduced.

Further, since the diaphragm type pressure regulator is used as the pressure regulator, the effect of reducing the pulsating flow and the pulsating pressure is further enhanced by the diaphragm.

Furthermore, since the pressure regulator is integrated into the pump body, the number of parts can be reduced and the discharge piping can be simplified.

[Brief description of the drawings]

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

FIG. 2 is a rear view showing the plunger type fuel pump.

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

FIG. 4 is a sectional view taken along line BB in FIG. 2;

5 (a) is an enlarged sectional view of a portion C in FIG. 4, and FIG. 5 (b) is an enlarged plan view of the suction valve 8 shown in FIG. 5 (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pump body, 1a cylinder accommodation hole, 1b suction port, 1c discharge path 1e return outlet, 1d pump discharge port 2 cylinder, 2a inflow path, 2b inflow groove 3 plunger, 3a long hole, 3b inflow hole, 3c suction path 4 pin 5, 6, 7 Compression coil spring 8 Intake flat valve 9 Discharge flat valve 10 Valve seat 11 Valve case 13 Plug, 13a screw, 13b Discharge hole 14 Pump chamber 15 O-ring 16 Diaphragm 17 Cap 20 Pump body cover 21 Countersunk screw 22 Drive Shafts 23, 24 Bearing 25 Oil seal 27 Cam chamber 28, 29 Nipple 30 O-ring 33 Pressure regulator 34 Pressure chamber 35 Pressure regulator cover 36 Diaphragm 37 Diaphragm holding member 38, 39 Compression coil spring 40 Bo Le 41 screw

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 59/44 F02M 59/44 E 69/00 340 69/00 340T F04B 1/04 F04B 9/04 C 1 / 047 1/04 1/053 9/04 (72) Inventor Takashi Saito 309 Toyama, Takizawa-mura, Takizawa-mura, Iwate-gun Inside Mikuniadekku Co., Ltd. (72) Ryo Shichi Toyama, Takizawa-mura, Takizawa-mura, Iwate-gun, Iwate No. 309 F-term in Miknia Deck (reference) 3G066 AA08 AB02 BA12 BA61 CA01S CA08 CA09 CB15 3H070 AA02 BB02 BB07 BB17 CC03 DD08 DD35 DD86 DD88 3H075 AA03 BB03 BB13 CC03 DA09 DA10 DB04 DB24

Claims (2)

[Claims] 1. A multi-plunger pump in which plungers are arranged at equal intervals in a radial direction with respect to a cam for driving the plungers, and the discharge flows of the plunger pumps formed by the plungers are combined. A plunger type fuel pump characterized in that a pressure regulator is provided integrally with the pump body at a position equidistant from the discharge valve and at the same flow volume. 2. The plunger type fuel pump according to claim 1, wherein said pressure regulator is a diaphragm type pressure regulator.