JP2001317428A - Fuel feed pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel feed pump that is controllable in force feed start timing. SOLUTION: Between a rotary part rotatable in synchronism with a propelling engine, and a driveshaft fixedly mounted with cams for driving plungers of a compressing mechanism for force-feeding fuel, a phase adjusting means is interposed to vary the phase of the driveshaft with respect to the axis of rotation. The lift timing of the plungers is thus variable with respect to the rotary part synchronized with the propelling engine, with the result that force feed start timing is adjustable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply pump for feeding fuel to a common rail in which high-pressure fuel is stored.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent No. 262353 is known.
The fuel injection control device for an internal combustion engine disclosed in No. 7 has a fuel supply passage having a pressure accumulation chamber for storing high-pressure fuel, a so-called common rail, and an injection connected to the common rail and connected to each cylinder of the internal combustion engine. A valve, a fuel supply pump for supplying fuel to the common rail, and a flow control valve for adjusting a flow rate of fuel flowing into the fuel supply pump, and a target of the common rail based on an operation state of the internal combustion engine. A pressure is set, and the flow control valve is controlled so that the pressure of the common rail becomes a target pressure.

In general, in a common rail system, it is desirable that the pressure in the common rail be constant. However, when the pressure in the common rail is reduced by the injection valve, the fuel supply pump simultaneously supplies the same amount of fuel as the injection amount. This is difficult, and the pressure of the common rail pulsates due to reflected waves generated in the high-pressure fuel system between the injection valve, the common rail, and the fuel supply pump. The generation of the pulsation causes instability of the injection amount and the injection pressure, and has a problem of causing a fuel failure of the engine.

[0004]

However, the above cited reference has a disadvantage that the pumping start timing cannot be controlled independently since the pumping start timing is determined by the fuel pumping amount which is required by the system. The problem cannot be solved.

[0005] Therefore, an object of the present invention is to provide a fuel supply pump capable of controlling the timing of starting pressure feeding.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a drive shaft, a cam fixed to the drive shaft, a plunger reciprocating along a cam surface by rotation of the cam, and a reciprocating motion of the plunger. A fuel supply pump for supplying fuel to a common rail connected to an injection nozzle disposed in each cylinder of the traveling engine, and rotating in synchronization with the traveling engine. A rotating unit and phase adjusting means for transmitting rotation of the rotating unit to the drive shaft and changing a phase of the drive shaft with respect to the rotary unit.

Therefore, according to the present invention, the rotating shaft is provided between the rotating portion that rotates in synchronization with the traveling engine and the drive shaft to which the cam that drives the plunger of the compression mechanism that feeds fuel is fixed. On the other hand, since the phase adjusting means for changing the phase of the drive shaft is provided, it is possible to change the push-up timing of the plunger with respect to the rotating part synchronized with the traveling engine, and it is possible to adjust the timing of starting the pressure feeding. Things.

[0008] Further, the phase adjusting means comprises at least a rotating plate fixed to the driving shaft, a driving plate on which the rotating portion is formed, and a displacement means for displacing the rotating plate with respect to the driving plate. The rotating plate has a pin protruding in the axial direction, and the displacement means is mounted eccentrically in the large cam provided on the driving plate and in the large cam. In addition, it is desirable to have a circular small cam on which the pin is eccentrically mounted, and a rotating means for rotating the large cam within a predetermined range.

Further, the turning means may be a fly weight which is displaced by centrifugal force due to the rotation of the driving plate, and the turning means may be a plunger which can be displaced by an external control means. good. Further, the external control means includes an oil supply means for supplying oil for displacing the plunger, an oil discharge means for discharging oil for returning the plunger to the original position, and the oil control means for controlling the oil by an external control signal. It is preferable that the control means include a switching means for switching between the supply means and the oil discharge means, and further, the external control signal is preferably calculated based on a detection result of a pressure detection means for detecting a pressure of the common rail.

[0010]

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

As shown in FIG. 1, the fuel supply pump 1
Has a housing 2 composed of housing members 2a, 2b, 2c, a fuel compression mechanism 3 in the housing member 2a, a fuel metering unit (FMU) 4 in the housing 2b, and a housing 2c. A drive mechanism 5 for driving the fuel compression mechanism 3 and a feed pump 6 are provided.

The drive mechanism 5 includes a rotating gear 7 that rotates in synchronization with a running engine (not shown).
A drive shaft 8 that rotates in conjunction with the drive shaft 2 and is rotatably held by the housing 2c; a pair of cams 9, 9 formed integrally with the drive shaft 8 and having different phases; A phase adjustment mechanism 10 provided between the drive shaft 8 and the drive shaft 8. An inner gear 11 for driving the feed pump 6 is fixed to one end of the drive shaft 8, and the feed pump 6 is driven by a drive gear 12 meshing with the inner gear 11. The feed pump 6 pumps up fuel from the fuel tank 13 and sends it to the fuel metering unit 4.
6a is an inflow terminal of the feed pump 6, 6b is an outflow terminal of the feed pump 6, and 4a is an inflow terminal of the fuel metering unit 4. Normally, a fuel filter is provided between the outflow terminal 6b of the feed pump 6 and the inflow terminal 4a of the fuel metering unit 4.

The fuel metering unit 4 adjusts the flow rate of the fuel flowing from the inflow terminal 4a and sends it to the compression mechanism 3 (not shown).
Is controlled by an external control signal supplied to the power supply. In the figure, reference numeral 4c denotes an overflow valve.

The compression mechanism 3 includes a cylinder 3a defining a compression chamber, the plunger 3b slidably moving within the cylinder 3a, and a plunger 3b provided at an end of the plunger 3b. The cam surface 9a of the formed cam 9
The tappet 3c moves along the cam surface 9a, and the spring 3d presses the tappet 3c toward the cam surface 9a. The rotation of the cam 9 causes the tappet 3c to move up and down along the cam surface 9a. 3b reciprocates in the cylinder 3a, compresses the fuel delivered from the fuel metering unit, and delivers it from the discharge port 14 to the common rail (15 shown in FIG. 3).
As shown in FIG. 3, the common rail 15 has a plurality of injection valves communicating therewith.
Is a pressure limiting valve.

As shown in FIG. 2, the phase adjusting mechanism 10 is fixed to a driving plate 7a on which the rotary gear 7 is formed and the driving shaft 8 by bolts 32 or the like, and protrudes in the axial direction. It comprises a rotating plate 30 on which pins 31 are formed, and a displacement mechanism 50 provided between the driving plate 7a and the rotating plate 30.

The displacement mechanism 50 includes the drive plate 7
a timing plate 33 which rotates together with a large circular cam 34 eccentrically mounted in the timing plate 33, a small cam 35 eccentrically provided in the large cam 34, and eccentrically provided in the large cam 34. 5, a fly weight 36 for moving the pin 38 radially outward of the timing plate 33, and a spring 37 for urging the fly weight 36 toward the center of the timing plate 33. It is constituted by and.

As a result, as shown in FIG. 5, when the rotation speed of the rotating gear 7 which rotates in synchronization with the traveling engine increases, the flyweight 36 moves radially outward of the timing plate 33 by centrifugal force. Moving. With the movement of the flyweight 36, the flyweight 36
The pin 38 mounted on the small cam 3 moves from E to E ', and the large cam 34 rotates about B, and the small cam 3
5 moves from C to C ′. Since the distance between the center C of the small cam 35 and the center D of the pin 31 projecting from the rotary plate 30 and eccentrically engaging with the small cam 35 is always equal, the pin 31 is moved with the movement of the small cam 35. Since the movement from D to D 'is made, the rotating plate 30 is advanced by θ with respect to the driving plate 7a. The movement of the fly weight 36 is controlled by the drive plate 7.
Since the rotation speed is proportional to the rotation speed a, the advance angle of the rotation plate 30 increases as the rotation speed increases. For this reason, the timing of feeding the fuel to the common rail 15 can be advanced with the increase in the rotation speed relative to the timing of the fuel injection, so that the fluctuation in the pressure of the common rail 15 can be suppressed.

Hereinafter, another embodiment of the present invention will be described. The same portions as those in the above-described embodiment or portions having similar effects are denoted by the same reference numerals and description thereof is omitted.

In the fuel supply pump 1 according to the embodiment shown in FIG. 3, the displacement mechanism of the phase adjustment mechanism 10 does not use a flyweight as described above but a mechanical signal using a control signal from a control unit 18. Controllable. In this embodiment, the control unit 18 uses the pressure detection signal input from the sensor 16 for detecting the pressure of the common rail 15 to
The fluctuation of the pressure in the common rail 15 is constantly traced, and when the fluctuation of the pressure becomes large (when pulsation of the pressure occurs), the displacement mechanism is controlled to control the common rail 1.
5 is controlled so as to suppress fluctuations in pressure.

FIG. 4 shows a specific example of the embodiment shown in FIG. The phase adjusting mechanism 10A shown in this embodiment includes a timing plate 33A that rotates together with the rotary gear 7,
3A, a large cam 34A eccentrically provided in the large cam 34A, a small cam 35A eccentrically provided in the large cam 34A, a pin 31A meshed with the small cam 35A,
A pin 38A meshes with A and a piston 40 that moves the pin 38A. When the solenoid 40 is energized, the connection block 21B communicates with the circuit by energizing the solenoid coil 22 of the solenoid valve 21. The oil pressurized by the pump 20 flows from the path 50 through the connection terminal 23, the oil passages 42 and 43. Then, the large cam 34A is rotated by pushing up the piston 40 and the rotary plate 30A is advanced with respect to the drive gear 7 as shown in FIG. When it is desired to return the advanced rotating plate 30A to its original state, the circuit is communicated by the connection block 21A, and the oil introduced into the pressure chamber 45 is returned to the oil chamber 90 via the path 51. Is to do so.

[0021]

As described above, according to the present invention, in the fuel supply pump for pumping the fuel to the common rail, the phase adjusting means for controlling the timing of starting the fuel supply pump is provided. Pulsation can be suppressed, and the injection amount and the injection pressure can be stabilized.
For this reason, since combustion in the engine can be stabilized, problems related to exhaust gas and the like, and problems related to engine rotation or output can be solved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel supply pump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a phase adjustment mechanism according to the embodiment of the present invention.

FIG. 3 is a sectional view of a fuel supply pump according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a specific example of the fuel supply pump shown in FIG.

FIG. 5 is an explanatory diagram illustrating a mechanism of a displacement mechanism.

[Explanation of symbols]

 Reference Signs List 1 fuel supply pump 2 housing 3 compression mechanism 4 fuel metering unit 5 drive mechanism 6 feed pump 7 rotation gear 8 drive shaft 9 cam 10 phase adjustment mechanism 15 common rail 30, 30A rotation plate 31, 31A pin 33, 33A timing plate 34, 34A Large cam 35, 35A Small cam 36 Fly weight

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/40 F02D 41/40 B F02M 47/02 F02M 47/02 F-term (Reference) 3G060 AA03 AB01 BA22 BA23 BB01 BB03 CA00 DA06 FA02 FA07 GA14 3G066 AA07 AB02 AC09 AD12 BA12 CA01S CA09 CA32U CA41 CA42 CD26 CE01 CE02 CE12 CE22 DC18 3G301 HA04 JA03 JA21 LB13 LC06 ND02 PB08A PB08Z

Claims (7)

[Claims] 1. A drive shaft, a cam fixed to the drive shaft, a plunger reciprocating along a cam surface by rotation of the cam, and a compression mechanism for sucking and compressing fuel by reciprocation of the plunger. A fuel supply pump for supplying fuel to a common rail connected to an injection nozzle arranged in each cylinder of the traveling engine, comprising: a rotating unit that rotates in synchronization with the traveling engine; A fuel supply pump comprising: a phase adjusting unit that transmits the drive shaft and changes a phase of the drive shaft with respect to the rotating unit. 2. The apparatus according to claim 1, wherein the phase adjusting unit includes at least a rotating plate fixed to the driving shaft, a driving plate on which the rotating unit is formed, and a displacement unit for displacing the rotating plate with respect to the driving plate. The fuel supply pump according to claim 1, wherein the fuel supply pump is operated. 3. The rotating plate has a pin protruding in the axial direction. The displacement means has a large circular cam provided on the driving plate, and is mounted eccentrically in the large cam and the pin is eccentric. 3. The fuel supply pump according to claim 2, further comprising: a circular small cam which is eccentrically mounted, and a rotating means for rotating the large cam within a predetermined range. 4. The fuel supply pump according to claim 3, wherein said rotating means is a flyweight which is displaced by centrifugal force caused by rotation of said drive plate. 5. The apparatus according to claim 3, wherein said rotating means is a plunger displaceable by an external control means.
A fuel supply pump as described. 6. The oil supply means for supplying oil to displace the plunger, wherein the external control means comprises:
6. An oil discharging means for discharging oil to return the plunger to its original position, and switching means for switching between the oil supply means and the oil discharging means by an external control signal. Fuel supply pump. 7. The fuel supply pump according to claim 6, wherein said external control signal is calculated based on a detection result of a pressure detecting means for detecting a pressure of a common rail.