JP2004218547A - High pressure fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform adjustment of an injection-valve opening pressure of a pressure relief valve 22 by incorporating the pressure relief valve 22 to a discharge valve 25 part of a high pressure fuel pump, and to enable reduction in size and weight of the entire high pressure fuel pump. <P>SOLUTION: An attention is paid that the pressure relief valve 22 is not mounted to a common rail 8 (accumulator) but is integrated into the discharge valve 25 of the high pressure fuel pump. The high pressure fuel pump comprises: a plunger 33 which sucks fuel from an intake valve 31 into a pump chamber 46 and discharges the fuel as a high pressure from the discharge valve 25 to the accumulator 8; and a solenoid valve 14 for controlling opening/closing of the intake valve 31. In this high pressure fuel pump, the pressure relief valve 22 capable of controlling a pressure of the accumulator 8 is arranged inside a discharge valve housing 49 of the discharge valve 25. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-pressure fuel pump, and more particularly to a high-pressure fuel pump provided in a direct injection fuel injection device for directly injecting gasoline or other fuel into a combustion chamber of an internal combustion engine.
[0002]
[Prior art]
A conventional high-pressure fuel pump will be outlined based on FIG.
FIG. 11 is a schematic circuit diagram of the fuel injection device 1 including the high-pressure fuel pump 5. The fuel injection device 1 includes a fuel tank 2, a feed pump 3 (low-pressure pump), a low-pressure regulator 4, and a variable displacement. It has a high-pressure fuel pump 5 of a type, an orifice 7 provided in a high-pressure pipe 6, a common rail 8 (pressure accumulator), a pressure relief valve 9, and a plurality of injectors 10.
[0003]
The feed pump 3 is driven by an electric motor (not shown) or the like, and supplies fuel such as gasoline to the high-pressure fuel pump 5.
The low pressure regulator 4 controls the pressure of the fuel by the feed pump 3.
[0004]
The high-pressure fuel pump 5 has a filter 11, a low-pressure damper 12, and a high-pressure pump unit 13.
An electromagnetic valve 14 is provided integrally with the high-pressure pump unit 13.
[0005]
In the fuel injection device 1 and the high-pressure fuel pump 5 having such a configuration, the fuel pressurized by the high-pressure fuel pump 5 is supplied to the common rail 8 through the high-pressure pipe 6 and the orifice 7, and the common rail 8 is supplied according to the fuel injection from the injector 10. The high-pressure fuel pump 5 is operated so as to maintain the pressure in the common rail 8 within a predetermined range, and the abnormal pressure in the common rail 8 is opened by opening the pressure relief valve 9 as a safety valve, and the high-pressure fuel pump 5 (high-pressure fuel pump 5) is opened. The pressure is released to the low pressure side of the pump section 13) to control the pressure.
[0006]
In a conventional high-pressure pump, for example, in Patent Document 1, such a pressure relief valve (safety valve) is provided in a pump housing.
However, since the pressure relief valve 9 is provided in the pump housing, there are problems that the pump housing is correspondingly enlarged and it is difficult to adjust the opening pressure of the pressure relief valve.
[0007]
[Patent Document 1]
JP-A-11-230025
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a high-pressure fuel pump incorporating a pressure relief valve without increasing the size of a high-pressure fuel pump or its pump housing.
[0009]
Another object of the present invention is to provide a high-pressure fuel pump that can easily adjust the valve opening pressure of a pressure relief valve.
[0010]
It is another object of the present invention to provide a high-pressure fuel pump in which a pressure relief valve is incorporated in a discharge valve portion of a high-pressure fuel pump so that the whole can be reduced in size and weight.
[0011]
[Means for Solving the Problems]
That is, the present invention focuses on integrating the pressure relief valve into the discharge valve of the high-pressure fuel pump instead of attaching it to the common rail (accumulator), and sucks the fuel from the fuel tank from the suction valve into the pump chamber. A high-pressure fuel pump having a plunger that discharges the fuel at a high pressure from a discharge valve to a pressure accumulator, and an electromagnetic valve that controls opening and closing of the suction valve, wherein the pressure accumulator is disposed in a discharge valve housing of the discharge valve. And a pressure relief valve capable of controlling the pressure of the fuel pump.
[0012]
By providing a partition in the discharge valve housing, a discharge valve mounting space in which the discharge valve can be incorporated, a pressure relief valve mounting space in which the pressure relief valve can be incorporated, and a port communication passage capable of communicating with the pressure accumulator. And can be defined.
[0013]
The pressure relief valve can control the pressure immediately after the discharge valve.
[0014]
In the high-pressure fuel pump according to the present invention, since the pressure relief valve is integrated with the discharge valve of the high-pressure fuel pump, the fuel injection device or the whole high-pressure fuel pump can be reduced in size without providing a pressure relief valve on the common rail. In addition to achieving weight reduction, the control pressure by the pressure relief valve can be made as flat as possible.
Further, it is possible to easily adjust the valve opening pressure of the pressure relief valve at the discharge valve portion.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a high-pressure fuel pump according to an embodiment of the present invention will be described with reference to FIGS. However, the same parts as those in FIG. 11 are denoted by the same reference numerals, and the detailed description thereof is omitted.
FIG. 1 is a schematic circuit diagram of a fuel injection device 20 provided with the high-pressure fuel pump. In the fuel injection device 20, like the fuel injection device 1 of FIG. , A low-pressure regulator 4, a variable-pressure high-pressure fuel pump 21, an orifice 7 provided in the high-pressure pipe 6, a common rail 8, and a plurality of injectors 10. Incorporated in.
[0016]
FIG. 2 is a sectional view of the high-pressure fuel pump 21. The high-pressure fuel pump 21 has a pump housing 23 provided with a suction port 24, a discharge valve 25 and a discharge port 26, a low-pressure damper 27, and a high-pressure fuel pump 21. And a pump unit 28.
The low-pressure damper 27 is provided facing the fuel supply passage 29, and a high-pressure pump 28 is provided between the fuel supply passage 29 and the fuel discharge passage 30.
[0017]
The high-pressure pump unit 28 includes the electromagnetic valve 14, a suction valve 31, a plunger barrel 32, and a plunger 33.
[0018]
The solenoid valve 14 is classified into a normally open type in which the suction valve 31 is "open" in the non-excited state and a normally closed type in which the suction valve 31 is "closed" in the non-excited state. The solenoid valve 14 shown in FIG. 2 is of a normally closed type, and includes a valve case 34, a solenoid 35, an armature 36 and an integral rod 37, a return spring 38, a ball 39, The armature 36 is sucked into the valve case 34 when the solenoid 35 is turned on, having the ball fixing portion 40 and the valve seat 41.
The suction valve 31 is provided facing the tip of the armature 36 (the tip 37A of the rod 37).
[0019]
The suction valve 31 has a valve body 42, a valve spring 43, and a valve stopper 44.
A suction passage 45 is formed in the valve seat 41, and the valve body 42 of the suction valve 31 lifts from the lower surface of the valve seat 41 and seats on the lower surface, so that the suction passage 45 can be opened and closed.
The plunger barrel 32 accommodates the plunger 33 so as to be reciprocally slidable in the axial direction, and forms a pump chamber 46 communicating with the fuel discharge passage 30 and the suction valve 31 between the plunger 33 and the top. A plunger spring 47 is provided below the plunger 33. The valve stopper 44 has a communication port 48 communicating with the pump chamber 46.
The plunger 33 is driven by a cam (not shown) of the engine to perform a fuel compression operation in the pump chamber 46.
[0020]
FIG. 3 is an enlarged cross-sectional view of the pressure relief valve 22, the discharge valve 25, and the discharge port 26. In the discharge valve 25, the inside of the discharge valve housing 49 from the fuel discharge passage 30 to the discharge port 26 is formed by a partition wall 50. A discharge valve mounting space 51, a pressure relief valve mounting space 52, and a port communication passage 53 are defined.
In the discharge valve mounting space 51, a valve seat 54, a valve body 55, a valve spring 56, and a spring seat 57 are provided as the discharge valve 25.
In the pressure relief valve mounting space 52, as the pressure relief valve 22, a ball valve seat 58, a ball valve 59, a movable spring seat 60 and a fixed spring seat 61, a valve spring 62, and a valve opening pressure adjusting ball 63 The communication window 64 of the spring seat 57 and the low pressure side communication window 65 of the discharge valve housing 49 can be communicated with each other by the lift of the ball valve 59 from the ball valve seat 58. The low pressure side communication passage 66 between the housing 49 and the pump housing 23 can communicate with the fuel supply passage 29 so that pressure is released to the low pressure side.
An O-ring 67 is provided between the discharge valve housing 49 and the pump housing 23 as a seal member.
[0021]
The operation of fuel intake and discharge by the fuel injection device 20, the high-pressure fuel pump 21, and the normally closed type solenoid valve 14 having such a configuration will be described.
The plunger 33 performs a suction operation of the fuel into the pump chamber 46 and a discharge operation from the pump chamber 46, and controls the timing of the fuel discharge by turning on and off the solenoid valve 14, thereby making the fuel discharge capacity variable.
FIG. 4 is a timing chart showing the lift of the cam, the signal to the solenoid valve 14, the movement of the suction valve 31 (valve body 42), and the discharge of fuel. In the excited state, the armature 36 is separated from the valve case 34 by the urging force of the return spring 38, the top of the rod 37 abuts against the ball 39, and the rod 37 is positioned inward from the lower surface of the valve seat 41. The suction passage 45 is closed by the urging force of the valve spring 43 (and the high pressure of the pump chamber 46 in the compression step by the plunger 33) of the valve body 42 of the suction valve 31.
Therefore, with the solenoid 35 turned off, the plunger 33 moves up, and the operation of discharging fuel from the pump chamber 46 to the discharge valve 25 via the fuel discharge passage 30 can be performed.
[0022]
When the solenoid 35 is turned on and the armature 36 is lifted (down) until it comes into contact with the upper surface of the valve case 34, the distal end portion 37A of the rod portion 37 slightly projects toward the suction valve 31, and the valve body of the suction valve 31 The suction passage 45 is slightly "opened" against the urging force of the valve spring 43 so that a spill passage that enables low-pressure spill can be formed.
The low pressure spill state refers to a state in which fuel is supplied from the pump chamber 46 to the low pressure side due to the fuel compression action of the plunger 33. Therefore, when the solenoid valve 14 is operating in a normal state, the common rail 8 side is at a high pressure, so that the discharge valve 25 is not opened and the suction port 31 or the fuel tank is moved from the suction valve 31 (suction passage 45) side. Spill fuel on two sides. On the other hand, if the solenoid valve 14 fails while the solenoid 35 is off, the pressure in the common rail 8 becomes lower due to the fuel injection by the injector 10, the discharge valve 25 is opened to form a spill passage, and the low pressure is applied to the common rail 8 side. Since the fuel can be supplied, it is possible to avoid a situation in which the engine is stopped.
Further, the solenoid 35 is switched from on to off, the suction valve 31 is closed, and the discharge of fuel is started with the rise of the plunger 33 from the bottom dead center. Thereafter, the same fuel suction and discharge operations are performed.
By changing the timing at which the electromagnetic valve 14 is turned off, the start point of the discharge can be controlled, and the fuel discharge amount can be made variable.
[0023]
Thus, in the suction process, regardless of whether the solenoid 35 is on or off, when the plunger 33 is lowered, the valve body 42 is opened to the maximum until it comes into contact with the valve stopper 44.
In the discharge step, as a preceding stage, when the solenoid 35 is turned on, the armature 36 is attracted to the upper protruding portion 34A of the valve case 34 against the urging force of the return spring 38, so that the valve body 42 is connected to the rod of the armature 36. Since the valve body 42 is in contact with the portion 37 and the valve body 42 is open, discharge is not performed and fuel is spilled to the low pressure side.
Further, the solenoid 35 is turned off, the armature 36 is held in the valve closing direction by the return spring 38, the valve body 42 abuts against the lower surface of the valve seat 41, the suction valve 31 is closed, and fuel discharge starts. .
[0024]
5 and 6 are graphs showing the state of the pressure relief valve 22 at the time of operation. FIG. 5 shows the relationship between time and pressure, and FIG. 6 shows an enlarged part of the graph. I have.
As shown in FIG. 5, the pressure in the pump chamber 46 (dotted line in the figure) changes due to the reciprocating motion of the plunger 33, and the pressure immediately after the discharge valve 25 and immediately before the pressure relief valve 22 (solid line in the figure) is The pressure in the common rail 8 (thick dotted line in FIG. 5) becomes substantially constant by the action of the pressure relief valve 22.
That is, as compared with the conventional case where the pressure relief valve 22 is directly attached to the common rail 8 as shown in FIG. Irrespective of the magnitude of the discharge flow rate from the pump, high-pressure fluctuations in the pump chamber 46 can be immediately leaked to the low-pressure side and controlled.
In particular, as shown in an enlarged manner in FIG. 6, the pressure relief valve 22 located immediately after the discharge valve 25 can immediately control the high pressure portion, so that the pressure in the common rail 8 can be controlled more flatly. is there.
[0025]
FIG. 7 is a graph showing the relationship between the flow rate of the high-pressure fuel pump 21 and the control pressure.
As shown in FIG. 7, in the low flow rate region of the high-pressure fuel pump 21, since the overshoot of the plunger 33 in the pump chamber 46 is small, the pressure in the discharge valve mounting space 51 immediately after the discharge valve 25 or the port communication passage 53 and There is no significant difference from the pressure in the common rail 8.
However, the overshoot of the plunger 33 in the pump chamber 46 increases as the flow rate of the high-pressure fuel pump 21 increases, and when the pressure relief valve 22 is mounted on the common rail 8 as in the related art (see FIG. 11). As shown by the dotted line in FIG. 7, there is a possibility that the pressure fluctuation immediately after the discharge valve 25 becomes large and the control pressure rises.
On the other hand, when the pressure relief valve 22 is integrated with the discharge valve 25 and is mounted immediately after the pressure relief valve 22 as in the present invention, the pressure fluctuation in the pressure relief valve mounting space 52 in which the pressure relief valve 22 is mounted causes the pressure fluctuation in the common rail 8 portion. Therefore, even if the flow rate of the high-pressure fuel pump 21 increases and the pressure fluctuation immediately after the discharge valve 25 increases, the pressure relief valve 22 located in the pressure relief valve mounting space 52 next to the discharge valve mounting space 51 Can immediately control the pressure, the control pressure decreases, and as shown by the solid line in FIG. 7, the control pressure of the common rail 8 can be flattened, and desired pressure control characteristics can be obtained.
In this way, a flat control pressure is obtained with respect to the flow rate, the pressure in the common rail 8 is gradually lowered, and the pressure can be reduced promptly even when the injector 10 is abnormally injected. Sometimes safe.
[0026]
The valve opening pressure of the pressure relief valve 22 can be adjusted by the amount of press-fit of the valve opening pressure adjusting ball 63 operable from the discharge port 26, and the pressure adjustment is easy.
[0027]
Further, a discharge valve mounting space 51, a pressure relief valve mounting space 52, a port communication passage 53, and the like are defined by utilizing an extra space in the discharge valve housing 49 of the discharge valve 25, and a pressure is applied to the pressure relief valve mounting space 52. Since the relief valve is provided, the whole can be reduced in size and weight and cost can be reduced.
[0028]
Further, when the pressure relief valve 22 is not provided in the portion of the discharge valve 25, the O-ring 67 for sealing between the discharge valve housing 49 and the pump housing 23 needs to be a high-pressure seal. By integrating the discharge valve 25 and the pressure relief valve 22 as in the present invention, the O-ring 67 can be used as a low-pressure seal.
In other words, even if the pressure inside the discharge valve housing 49 becomes abnormally high, the pressure relief valve 22 opens to adjust the pressure, so that the seal between the discharge valve housing 49 and the pump housing 23 does not have to be a high pressure type. A low-pressure type is sufficient, and all parts relating to external leakage of fuel can be of a low-pressure type.
[0029]
In the present invention, the configuration of the solenoid valve 14 is arbitrary, and the integral structure of the discharge valve 25 and the pressure relief valve 22 or the mounting structure of the pressure relief valve 22 in the discharge valve 25 can adopt any form. .
For example, FIG. 8 is a cross-sectional view of a main part showing a first modification of the mode of attaching the pressure relief valve 22 to the discharge valve 25. In this mode, a second partition 68 orthogonal to the partition 50 is provided. Here, the spring seat 57 of the discharge valve 25 and the valve spring 62 of the pressure relief valve 22 are seated.
The opening direction of the discharge valve 25 and the opening direction of the pressure relief valve 22 are opposite to each other, and the ball valve 59 of the pressure relief valve 22 receives high pressure from the discharge valve 25 side via the port communication passage 53. become.
The valve opening pressure of the pressure relief valve 22 can be adjusted by the amount of press-fit of the ball valve seat 58.
[0030]
FIG. 9 is a cross-sectional view of a principal part showing a second modification of the mounting mode of the pressure relief valve 22. In this embodiment, the pressure relief valve 22 is provided at a position eccentric from the center of the discharge valve housing 49. , A plurality of port communication passages 53 are formed.
[0031]
FIG. 10 is a cross-sectional view of a principal part showing a third modification of the mounting mode of the pressure relief valve 22. In this embodiment, the pressure relief valve 22 is provided at a central position of the discharge valve housing 49, and around the same. A plurality of port communication paths 53 are formed radially.
[0032]
【The invention's effect】
As described above, according to the present invention, since the pressure relief valve is integrated into the discharge valve, the whole can be reduced in size and weight and the cost can be reduced, and the pressure relief valve can be easily replaced. Adjustments can also be made appropriately.
[Brief description of the drawings]
FIG. 1 is a schematic circuit diagram of a fuel injection device 20 including a high-pressure fuel pump 21 according to an embodiment of the present invention.
FIG. 2 is a sectional view of the high-pressure fuel pump 21;
FIG. 3 is an enlarged sectional view of a pressure relief valve 22, a discharge valve 25, and a discharge port 26 in the same manner.
FIG. 4 is a timing chart showing a lift of a cam, a signal to an electromagnetic valve 14, movement of a suction valve 31 (valve body 42), and discharge of fuel.
FIG. 5 is a graph showing a state when the pressure relief valve 22 is actuated, showing a relationship between time and pressure.
FIG. 6 is a graph showing the state of the pressure relief valve 22 during operation, and shows a main part of the graph of FIG. 5 in an enlarged manner.
FIG. 7 is a graph showing a relationship between a control pressure and a flow rate by the high-pressure fuel pump 21;
FIG. 8 is a cross-sectional view of a main part showing a first modified example of an attachment form of the pressure relief valve 22 to the discharge valve 25.
FIG. 9 is a cross-sectional view of a main part showing a second modified example of the mounting form of the pressure relief valve 22.
FIG. 10 is a cross-sectional view of a main part showing a third modified example of the mounting form of the pressure relief valve 22.
FIG. 11 is a schematic circuit diagram of a fuel injection device 1 including a conventional high-pressure fuel pump 5.
[Explanation of symbols]
1. Fuel injection device (Fig. 11)
2 Fuel tank 3 Feed pump (low pressure pump)
4 Low pressure regulator 5 High pressure fuel pump 6 High pressure pipe 7 Orifice 8 Common rail (accumulator)
9 Pressure relief valve 10 Injector 11 Filter 12 Low pressure damper 13 High pressure pump unit 14 Solenoid valve 20 Fuel injection device (FIG. 1)
21 High-pressure fuel pump (embodiment, FIG. 2)
22 Pressure relief valve 23 Pump housing 24 Suction port 25 Discharge valve 26 Discharge port 27 Low pressure damper 28 High pressure pump unit 29 Fuel supply passage 30 Fuel discharge passage 31 Suction valve 32 Plunger barrel 33 Plunger 34 Valve case 34A Upper projection of valve case 34 35 Solenoid 36 Armature 37 Rod part 37A of armature 36 Tip part 38 of rod part 37 Return spring 39 Ball 40 Ball fixing part 41 Valve seat 42 Valve body 43 Valve spring 44 Valve stopper 45 Suction passage 46 Pump chamber 47 Plunger spring 48 Communication port 49 Discharge valve housing 50 Partition wall 51 Discharge valve mounting space 52 Pressure relief valve mounting space 53 Port communication passage 54 Valve seat 55 Valve body 56 Valve spring G 57 spring seat 58 ball valve seat 59 ball valve 60 movable spring seat 61 fixed spring seat 62 valve spring 63 valve opening pressure adjustment ball 64 communication window 65 low pressure side communication window 66 low pressure side communication passage 67 O-ring 68 second partition (FIG. 8)

Claims (3)

A plunger that draws fuel from a fuel tank from a suction valve into a pump chamber and discharges the fuel as high pressure from a discharge valve to a pressure accumulator;
An electromagnetic valve that controls the opening and closing of the suction valve.
A high-pressure fuel pump, wherein a pressure relief valve capable of controlling the pressure of the accumulator is provided in a discharge valve housing of the discharge valve. By providing a partition in the discharge valve housing,
A discharge valve mounting space in which the discharge valve can be incorporated,
A pressure relief valve mounting space in which the pressure relief valve can be incorporated,
The high-pressure fuel pump according to claim 1, wherein a port communication passage that can communicate with the pressure accumulator is defined. The high pressure fuel pump according to claim 1, wherein the pressure relief valve is capable of controlling a pressure immediately after the discharge valve.

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