JP2002054531A - Piston type high pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston type high pressure pump capable of being low in a cost, high in reliability, and improving seal performance by coping with increase in a discharge pressure. SOLUTION: The piston type high pressure pump is emphasized that sealing is effected at three stages of the high pressure part of a pump chamber 29, the suction pressure part situated upper stream from a suction valve 22, and a low pressure part where leak through the periphery of a piston 3 occurs; and the suction pressure part is introduced to the periphery of a piston 3. The piston type high pressure pump comprises a first seal mechanism 45 to seal a gap between the high pressure part of the pump chamber 29, communicating with the suction valve 22 and a discharge valve 23, and a suction pressure part situated in upper stream from the suction valve 22; and a second seal mechanism 46 to seal a space between the suction pressure part and the low pressure part leaking from the periphery of the piston 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston-type high-pressure pump, and more particularly to a piston-type high-pressure pump such as a pump for gasoline and other low-viscosity fuels and a pump for other fluids.

[0002]

2. Description of the Related Art Conventional piston type high pressure pumps
An outline will be given based on FIG. FIG. 3 is an explanatory view showing a graph of a piston type high pressure pump 1 applied to, for example, a high pressure gasoline pump and a piston lift in the operation thereof. ) And tappet 4
, A solenoid valve 5, a suction valve 6 and a discharge valve 7, and a driving cam 8.

A pump chamber 9 is formed between the pump cylinder 2 and the piston 3.

The piston 3 reciprocates up and down in the pump cylinder 2 as shown in the drawing, and feeds fuel into a pump chamber 9 through a suction passage 12 from a fuel tank 10 and a feed pump 11 and further through a suction valve 6 of a solenoid valve 5. The fuel is sucked and opened against the urging force of the discharge valve spring 13 in the discharge valve 7 to discharge the fuel into the discharge passage 14.

[0005] The solenoid valve 5 functions as a control valve for opening and closing the suction valve 6, and has a valve body portion serving as the suction valve 6.
Solenoid 15 and control valve spring 1
6 controls the opening and closing of the suction valve 6.

The cam 8 is driven to rotate by an engine or the like, thereby reciprocatingly driving the piston 3 in the pump cylinder 2 via the tappet 4.

In the piston-type high-pressure pump 1 having such a configuration, as shown in the graph of FIG. 3, when the time is taken on the horizontal axis and the lift of the piston 3 is taken on the vertical axis, FIG. At the start of the fuel intake, and at this time, the intake valve 6 of the solenoid valve 5 is open. FIG. 3 (2) shows a state in which the piston 3 has started to rise. Between the state shown in FIG. 3 (2) and the fuel discharge state shown in FIG. 3 (3), the solenoid 15 of the solenoid valve 5 is turned on. Turn on the intake valve 6 and close the piston 3
When the predetermined valve opening pressure set by the discharge valve spring 13 is reached, the discharge valve 7 opens and discharges the fuel into the discharge passage 14. From the state of FIG. 3 (3), the solenoid valve 5 is turned off, the suction valve 6 is opened, and the fuel discharge is completed. Thus, the piston type high pressure pump 1
, The suction valve 6 in the solenoid valve 5
By controlling the valve opening and valve closing operations (valve closing timing), the amount of fuel to be discharged is adjusted.

When the piston-type high-pressure pump 1 is configured to control the valve closing timing, FIG.
As shown in (2) to FIG. 3 (3), the cam 8 generates a high pressure in the pump chamber 9 at the time of cam top where the radius of curvature is minimum, and the contact surface between the cam 8 and the tappet 4 When the pressure becomes excessive, the piston 3, the tappet 4 and the cam 8
There is a problem of abrasion, such as wear, and in particular, a problem of lack of reliability in long-term use.

Further, as the required discharge pressure of the piston-type high-pressure pump 1 increases, there is a demand for improvement in sealing performance between the pump cylinder 2 and the piston 3 and in the pump chamber 9. Conventionally, a high pressure part (in the pump chamber 9) and a low pressure part (the fuel tank 10)
Only various sealing mechanisms for sealing between the inside and the atmospheric pressure are employed, and there is a problem that the improvement in sealing performance is limited due to the large pressure difference.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a low-cost and highly reliable piston-type high-pressure pump in response to an increase in discharge pressure. As an issue.

Another object of the present invention is to provide a piston-type high-pressure pump capable of improving sealing performance as a piston-type high-pressure pump.

Another object of the present invention is to provide a piston-type high-pressure pump in which the contact surface pressure between the tappet and the cam is prevented from becoming excessive.

[0013]

That is, the present invention provides sealing in three stages: a high pressure section in a pump chamber, a suction pressure section upstream of a suction valve, and a low pressure section leaking from around a piston. Focusing on guiding the suction pressure part around the piston, a fluid suction valve and a discharge valve, and a piston barrel forming a pump chamber communicating with the suction valve and the discharge valve;
A piston-type high-pressure pump having a piston that performs fluid suction from the suction valve and discharges fluid from the discharge valve by reciprocating in the piston barrel, and a cam that drives the piston. A first sealing mechanism for sealing between a high-pressure part in the pump chamber and a suction pressure part upstream of the suction valve, and a low-pressure part leaking from around the piston and the suction pressure part. And a second seal mechanism for sealing the piston.

The piston may sequentially face the high-pressure portion, the suction pressure portion, and the low-pressure portion from a portion facing the pump chamber to a portion on the cam side.

[0015] The first seal mechanism may have a face seal portion such as a metal seal portion.

[0016] A third seal mechanism for sealing between the low pressure portion and the cam or the spring chamber of the tappet may be provided.

A control valve capable of controlling the pressure of the pump chamber is provided, and by adjusting the valve opening timing of the control valve, the timing of terminating the fluid discharge of the discharge valve can be controlled.

In the piston type high pressure pump according to the present invention, a first seal mechanism for sealing between a high pressure portion in the pump chamber and a suction pressure portion upstream of the suction valve, a suction pressure portion and the piston are provided as a seal mechanism. A second sealing mechanism for sealing between a low pressure portion leaking from the periphery of the high pressure portion and a low pressure portion, wherein the pressure portion to be sealed has a three-stage configuration (high pressure portion, suction pressure portion, low pressure portion). By interposing a suction pressure portion between the pressure and the pressure, the sealing pressure can be gradually reduced, and the sealing performance can be improved even when the discharge pressure is increased.

Further, while the conventional piston type high pressure pump is configured to control the closing timing of the solenoid valve (control valve), the opening timing of the control valve is controlled. If the area of use of the cam is determined to be a region having a large radius of curvature in accordance with the control, a fluid compression action is not performed at the time of cam top, that is, no high pressure is generated in the pump chamber, and a gap between the cam and the tappet Does not become excessively large.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a piston type high pressure pump 20 according to an embodiment of the present invention will be described with reference to FIGS. However, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is a longitudinal sectional view of a piston type high pressure pump 20. The piston type high pressure pump 20 is a single cylinder type high pressure gasoline pump, and includes a pump housing 21, a suction valve 22, and a discharge valve 23.
A control valve 24 by an electromagnetic valve; a piston barrel 25 (plunger barrel);
It has a tappet 4 and a cam 8 and a low-pressure damper 26.

An annular suction passage 27 and a communication passage 28 are formed in the pump housing 21 from a suction port connected to the fuel tank 10.
At 6, the low pressure pulsation is reduced to reach the suction valve 22.

The suction valve 22 faces a pump chamber 29 formed in the piston barrel 25. A high-pressure port 30 is formed across the pump housing 21 and the piston barrel 25 so as to penetrate the pump chamber 29 at right angles to the reciprocating direction of the piston 3.
0 and the discharge valve 23 and the control valve 2
4 faces the same, and the head of the piston 3 is
I am facing 9.

The discharge valve 23 can discharge high-pressure fuel from the discharge port 31 to, for example, a common rail (pressure accumulator, not shown).

The control valve 24 is provided with a pump chamber 29
And controls the timing of the pumping of the fuel and particularly the end thereof (closing of the discharge valve 23). The solenoid 32, the armature 33, the valve body 34,
And a seat portion 35 of the valve body 34. By lifting the valve body 34 from the seat portion 35,
The pump chamber 29 can communicate with the annular suction passage 27 from the pump chamber 29 via the shaft passage 36 and the suction-side communication passage 37.

The suction pressure guiding passage 3 communicates with the shaft passage 36.
8. An inner wall annular groove 39 and a leak hole 40 are formed. A circumferential groove 41 is formed in the piston 3 at a substantially middle position in the length direction in the circumferential direction, and the piston 3 can be recirculated from the low-pressure side passage 43 to the fuel tank 10 through an orifice 42 formed in the pump housing 21. . Low pressure side passage 43
Is connected to the circumferential portion on the tappet 4 side (the lower side in the figure) from the circumferential groove 41 of the piston 3 via the leak passage 44.
Therefore, the circumferential groove 41 portion of the piston 3 receives the suction pressure in the annular suction passage 27 via the suction pressure guiding passage 38, and the circumferential portion below the circumferential groove 41 is the fuel tank. This means that a pressure equivalent to the low pressure of 10 parts is received.

Next, the first seal mechanism 45 between the pump housing 21 and the piston barrel 25, the piston 3
A second sealing mechanism 46 between the piston barrel 25 and
The third seal mechanism 47 between the lower portion of the piston 3 and the tappet 4 will be described. First sealing mechanism 45
Are the high pressure part (pump chamber 9) and the suction pressure part (suction passage 27)
And has a metal seal portion 48 (face seal portion) between the pump housing 21 and the piston barrel 25, a high-pressure side O-ring 49, and a backup ring 50. The high pressure in 29 is sealed.

The second seal mechanism 46 seals between the suction pressure portion and the low pressure portion leaking from around the piston 3, has a suction pressure side O-ring 51, and has an orifice 42.
Hole 40 or circumferential groove 41 pressure-separated by
And the low pressure side passage 43 or the leak passage 44 are sealed.

The third seal mechanism 47 includes a low pressure portion and a cam 8.
And a seal member 52 is provided below the piston 3 (below the circumferential groove 41).
A low pressure side O-ring 53 is provided between the pump housing 21 and the piston barrel 25. Thus, tappet 4
, A spring chamber 55 accommodating a tappet spring 54 and a low pressure side passage 43 or a leak passage 44.
And seal between.

The piston type high pressure pump 20 having such a configuration
2 is an explanatory diagram showing a graph of the piston type high-pressure pump 20 and a piston lift in the operation thereof. In the fuel intake stroke as shown in FIG. The valve 23 and the control valve 24 are "closed". The control valve 24 closes the solenoid 32 by energizing the solenoid 32, thereby saving driving energy.

FIG. 2B shows a state in which the intake valve 22 is closed when the piston 3 is being lifted (compression stroke, discharge stroke).
When the predetermined valve opening pressure is reached, the discharge valve 23 is opened.
Becomes In the discharge end state shown in FIG. 2C, the control valve 24 is opened, and the discharge of the fuel from the discharge valve 23 ends. In the compression stroke shown in FIG. 2 (2), by adjusting the valve opening timing of the control valve 24, it is possible to control the timing of the fluid discharge of the discharge valve 23 to adjust the discharge amount.
An area where the radius of curvature of the cam 8 is small can be used,
The contact surface pressure between the cam 8 and the tappet 4 is small.

Thus, since the control valve 24 controls the valve opening timing, the pump pressure at the cam top is low, so that an excessive surface pressure between the tappet 4 and the cam 8 does not occur. Further, the control valve 24 is closed when the piston 3 starts to rise, but after the control valve 24 is opened and the discharge is completed, the valve is kept open when the piston 3 descends.
Until the valve is closed, fuel is sucked through the control valve 24 (ie, through the suction-side communication passage 37, the shaft passage 36, and the high-pressure port 30).
Inhalation efficiency is improved.

Further, the first sealing mechanism 45 and the second
Between the high pressure section of the pump chamber 29 and the feed pressure section (suction pressure section) of the feed pump 11 by the seal mechanism 46 of FIG.
And since it is designed to seal between the suction pressure part and the tank pressure part (low pressure part), that is, since the sealing mechanism seals the pressure in three stages,
The pump performance and safety can be improved as compared with the case where the high pressure part and the low pressure part on the fuel tank 10 side are directly sealed (partitioned). Since the metal seal portion 48, which is a face seal, is employed as the high-pressure seal in the first seal mechanism 45, the sealing performance can be ensured and the cost can be reduced.

Further, since the piston 3 and the low-pressure damper 26 are on the same axis, the fixing operation of these parts is easy, and the assembling workability can be improved and the cost can be reduced.
Further, since the control valve 24 and the high pressure port 30 are coaxial, the processing is easy.

[0034]

As described above, according to the present invention, the pressure part to be sealed by the sealing mechanism has a three-stage structure (high pressure part, suction pressure part, low pressure part), and the suction pressure is provided between the high pressure part and the low pressure part. The first seal mechanism and the second seal mechanism are used for sealing with the interposed portion, so that even if the discharge pressure is increased, the sealing performance is improved, and the piston type excellent in safety and reliability is provided. It can be a high pressure pump.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a piston type high pressure pump 20 according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a graph of a piston type high pressure pump 20 and a piston lift in the operation thereof.

FIG. 3 is an explanatory view showing a graph of a conventional piston type high pressure pump 1 and a piston lift in the operation thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston type high pressure pump (FIG. 3) 2 Pump cylinder 3 Piston (plunger) 4 Tappet 5 Solenoid valve 6 Suction valve 7 Discharge valve 8 Drive cam 9 Pump room 10 Fuel tank 11 Feed pump 12 Suction passage 13 Discharge valve spring 14 Discharge passage 15 Solenoid 16 Control valve spring 20 Piston type high pressure pump (Embodiment, FIG. 1) 21 Pump housing 22 Suction valve 23 Discharge valve 24 Control valve (solenoid valve) 25 Piston barrel (plunger barrel) 26 Low pressure damper 27 Annular Suction passage 28 Communication passage 29 Pump chamber 30 High pressure port 31 Discharge port 32 Solenoid 33 Armature 34 Valve body 35 Seat portion 36 Shaft passage 37 Suction side communication passage 38 Suction pressure induction passage 3 9 Inner wall annular groove 40 Leak hole 41 Circumferential groove 42 Orifice 43 Low pressure side passage 44 Leak passage 45 First seal mechanism 46 Second seal mechanism 47 Third seal mechanism 48 Metal seal part (face seal part) 49 High pressure side O-ring 50 Backup ring 51 Suction pressure side O-ring 52 Seal member 53 Low pressure side O-ring 54 Tappet spring 55 Spring chamber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuro Hozumi 3-13-26 Yaumicho, Higashimatsuyama-shi, Saitama Prefecture Bosch Automotive Systems Co., Ltd. Inside the Higashimatsuyama Plant (72) Inventor Tetsuyoshi Yamazaki 3 Yayanmachi, Higashimatsuyama-shi, Saitama No. 13-26, Bosch Automotive System Co., Ltd. Inside the Higashi-Matsuyama Plant (72) Inventor Kazuma Kasahara 3--13-26, Yayumicho, Higashi-Matsuyama City, Saitama Prefecture F-term (reference) 3G066 AA01 inside the Bosch Automotive System Higashi-Matsuyama Plant AB02 BA36 BA55 BA56 BA61 CA01S CA08 CA09 CD10 CE02 3H071 AA07 BB01 CC28 DD51 3H075 AA03 BB02 CC16 DA03 DA04 DA09 DA30 DB04 DB24

Claims (5)

[Claims] 1. A suction valve and a discharge valve for a fluid, a piston barrel forming a pump chamber communicating with the suction valve and the discharge valve, and a fluid reciprocating in the piston barrel to suck fluid from the suction valve. And a piston for discharging fluid from the discharge valve, and a cam for driving the piston, comprising: a high-pressure part in the pump chamber and suction at an upstream side of the suction valve. A first seal mechanism for sealing between the suction pressure section and a low pressure section leaking from around the piston; and a second seal mechanism for sealing between the suction pressure section and a low pressure section leaking from around the piston. Type high pressure pump. 2. The piston according to claim 1, wherein the piston faces the high-pressure portion, the suction pressure portion, and the low-pressure portion sequentially from a portion facing the pump chamber toward a portion on the cam side. 2. The piston type high pressure pump according to 1. 3. The high pressure piston type pump according to claim 1, wherein said first seal mechanism has a face seal portion. 4. The piston type high pressure pump according to claim 1, further comprising a third sealing mechanism for sealing between the low pressure portion and the cam. 5. A control valve capable of controlling the pressure of the pump chamber, wherein timing of ending the fluid discharge of the discharge valve is controlled by adjusting a valve opening timing of the control valve. The piston type high pressure pump according to claim 1.