JP2001289138A - Fuel supply pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection pump with an improved capacity of oil supply without a significant change of manufacturing facilities. SOLUTION: A fuel supply pump 50 comprises a camshaft 7 rotationally driven by an internal combustion engine, a cam 13 fixed to the camshaft 7 with cam crests 14 formed thereon, and a plunger 4 reciprocating along the shape of the cam 13, where the fuel is pressurized to be supplied to a high pressure by a reciprocating motion of the plunger 4. The fuel supply pump 50 comprises two or more of the plungers 4, pressurizing the fuel by at least two plungers 4 in a pressurizing period of the fuel.

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 used in automobiles and the like to supply fuel at a high pressure.

[0002]

2. Description of the Related Art In a conventional fuel supply pump, FIG.
As shown in FIG. 2, the two cams 13a and 13b fixed to the camshaft 7 are arranged such that the phases of the cam ridges formed on the respective cams are shifted from each other. The cams 13a and 13b arranged as described above allow the plunger barrel 5 to move.
Each of the two plungers 4a and 4b held slidably in the above-mentioned manner alternately pressurizes the fuel. That is, when one plunger 4a moves to the upper pressurized position, the other plunger 4b moves to the lower non-pressurized (suction) position.

[0003]

In the above-mentioned conventional fuel supply pump, there is a case where the fuel supply capacity is insufficient because only one plunger pressurizes the fuel at all times. In particular, in a common rail system that supplies fuel to a common rail with high pressure by a fuel supply pump, it is necessary to increase the pressure of the fuel compared to other fuel injection systems. It has been demanded.

However, in the conventional fuel supply pump as shown in FIG. 7, in order to increase the oil supply capacity of the fuel supply pump, it is necessary to increase the diameter of the plunger, increase the number of cam peaks, and increase the height difference. However, in such a method, it is necessary to newly manufacture each component such as a plunger, a plunger barrel, and a cam, and the compatibility of these components with existing products is lost. , Etc., need to be changed greatly, resulting in high costs.
Therefore, the inventor of the present invention can maintain the interchangeability of parts by changing the fixed angle of the cam or increasing the number of plungers. Focus on what you can do,
The present invention has been made.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel supply pump having improved oil supply capacity without significant changes in manufacturing equipment and the like.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a camshaft driven by an internal combustion engine, a cam fixed to the camshaft and formed with a plurality of cam ridges, A plunger that reciprocates along the shape of the cam, wherein the fuel supply pump supplies fuel at a high pressure by reciprocating the plunger. The fuel supply pump includes two or more plungers. The fuel is pressurized by a plunger (claim 1).

According to the fuel supply pump having such a configuration, the fuel is pressurized by the plurality of plungers at the time of pressurizing the fuel. Can be. In order to synchronize the fuel pressurization timing, the fixed angle of a specific cam may be adjusted so that the cam ridges have the same phase with each other. It can be performed easily and at low cost without requiring a significant change in Also, 1
Three plungers pressurize the fuel at each pressurization time,
As the number is increased to four,..., Three times, four times,... Such a change to increase the number of plungers and cams does not require significant changes in manufacturing equipment, etc., because the compatibility of each component such as plungers, plunger barrels, cams, etc. with existing products is maintained. It can be performed easily and at low cost.

It is preferable that the product of the number of the plungers and the number of the cam ridges formed on one cam is an integral multiple of the number of cylinders of the internal combustion engine.

According to this, the fuel is pumped by the fuel supply pump one or more times in synchronism with the timing of one fuel injection into the combustion chamber. It can be effectively supplemented. For example, 6
In the case of a cylinder engine, if the number of plungers is 4 and the number of cams is 3, the product is 12 and the number of cylinders is double, and if the number of plungers is 6 and the number of cams is 3, the product is 18 and the number of cylinders. If the number of plungers is six and the number of cam lobes is two, the number of cylinders is twice as large as the "product" 12. Further, with the above configuration, the degree of freedom in designing the fuel supply pump can be improved. For example, even if an attempt is made to change the cam shape for the purpose of improving the oil supply capacity of the fuel supply pump, if there are restrictions such as strength and pump driving torque, the number of cams (the number of plungers) is changed or one cam is required. This can be dealt with by changing the number of cam ridges formed.

Further, the fuel supply pump can be suitably used for supplying high-pressure fuel to a common rail.

A common rail system, which is one of the fuel injection systems for injecting fuel oil in a fuel tank into a combustion chamber of an internal combustion engine, requires a higher pressure of the fuel oil than other fuel injection systems. It is. Therefore, the fuel supply pump that can easily and at low cost improve the oil supply capacity can be particularly suitably used in a common rail system.

[0012]

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

A fuel supply pump 50 according to a first embodiment of the present invention shown in FIGS. 1 and 2 is used as a part of a common rail system 45 as shown in FIG. A common rail system 45 shown in FIG. 6 includes a fuel supply pump 50, a common rail assembly 51, an injector assembly 55, and an ECU 5 that controls these components.
8 and sensors 57.

The fuel supply pump 50 is connected to a common rail assembly 51 through a pipe, and supplies the common rail assembly 51 with high pressure fuel oil sucked from the fuel tank 40. The common rail assembly 51 stores the high-pressure fuel pumped from the fuel supply pump 50 and distributes the high-pressure fuel to the injector assembly 55. The injector assembly 55 supplies high-pressure fuel from the common rail 51 to a combustion chamber of an internal combustion engine (not shown) at an optimum injection timing and injection amount. The internal combustion engine according to the embodiment of the present invention has six cylinders. ECU5
8 is the engine speed detected by each sensor 57;
The fuel injection amount, injection timing, injection pressure, and the like are comprehensively controlled according to the accelerator opening and the like.

The structure of the fuel supply pump 50 according to the first embodiment will be described below with reference to FIGS. The fuel supply pump 50 is configured by assembling a supply pump 1, a fuel metering unit (FMU) 2, and a feed pump 3.

The feed pump 3 draws fuel oil from a fuel tank 40 and supplies the fuel oil to a fuel metering unit (FMU) 2 described later. Bolts and the like are used to close an opening of a housing member 8c of the pump housing 8. Installed by. Inside the feed pump 3, an internal gear fixed to the end of the camshaft 7, a drive gear meshing with the internal gear, a driving gear connected to the drive gear via the shaft, A driven gear meshed with the main driving gear, and the main shaft and the driven gear are rotated by rotation of the camshaft 7, and fuel oil is sucked from the fuel tank 40 by a gear pump constituted by these two gears. The fuel is supplied to a fuel metering unit (FMU) 2 described later via a fuel filter.

A fuel metering unit (FM)
U) 2 has a function of adjusting the amount of the fuel oil sent from the feed pump 3 so as to have a fuel pressure required by the engine and then feeding the adjusted fuel oil to a supply pump 1 described later. A throttle valve 32 is provided in the middle of a fuel passage 31 for guiding the fuel sent from the feed pump 3 from the fuel inlet 30 to the supply pump 1, and a pressure chamber 33 provided at one end of the throttle valve 32 is provided through an orifice 34. The fuel oil sent from the feed pump 3 is supplied to the throttle valve 32 at a position where the pressure of the pressure chamber 33 and the spring force of the spring 35 provided at the other end of the throttle valve 32 are balanced.
Is stopped, and the pressure in the pressure chamber 33 is adjusted by an electromagnetic valve 36 controlled by an electronic control unit (ECU) 58 (see FIG. 6), whereby the throttle of the fuel passage 31 is controlled and supplied to the supply pump 1. The amount of fuel oil to be supplied is adjusted.

The supply pump 1 comprises a plunger 4, a plunger barrel 5, a tappet 6, a camshaft 7, a cam 1
The camshaft 7 is supported by a pump housing 8, and one end of the camshaft 7 is supported by the pump housing 8.
6 cylinder internal combustion engine (not shown)
, And rotates in synchronization with the driving torque.

The pump housing 8 has a housing member 8a having a vertical hole 10 in which the plunger barrel 5 is mounted.
And housing members 8b and 8c fixed to the housing member 8a with bolts or the like and rotatably holding the vicinity of both ends of the camshaft 7.

A plunger 4 is reciprocally inserted into the plunger barrel 5, and below the plunger 4,
A cam 13 having three cam ridges 14 is fixed to the camshaft 7, and the lower end of the plunger 4 is in contact with the cam 13 via the tappet 6. As shown in FIG. 2, the spring 17 is mounted between the spring receiver 15 provided on the housing member 8a and the spring receiver 16 provided below the plunger 4, so that when the camshaft 7 rotates. The plunger 4 is reciprocated along the contour of the cam 13.

At the top of each plunger barrel 5, an IO valve (inlet / outlet valve) 20 is provided which is assembled between the plunger barrel 5 and the delivery valve holder 19. Between the IO valve 20 and the plunger 4,
A plunger chamber 21 is formed, and a fuel outlet 2 formed in a delivery valve holder 19 is provided above the IO valve 20.
2 are provided.

Here, the IO valve 20 supplies the fuel oil sent from the fuel metering unit (FMU) 2 to the plunger chamber 21 so that the fuel oil compressed by the plunger 4 does not flow back to the FMU 2. The valve body 23 has a function of delivering fuel from a fuel outlet 22 and is mounted on an upper part of the plunger barrel 5.
One end communicates with the FMU 2 and the other end is connected to the plunger chamber 21.
Passage 24 formed in valve body 23 communicating with
And an inlet valve 25 that constantly urges the fuel passage 24 in the closing direction by an urging force against the fuel pressure from the FMU 2, one end communicating with the plunger chamber 21, and the other end communicating with the fuel outlet 22. Valve 2 that opens and closes the fuel passage 26 to be closed and constantly urges the fuel passage 26 in the closing direction by a biasing force against the fuel pressure from the plunger chamber 21.
When the plunger 4 enters the lowering step, the outlet valve 27 is closed, the inlet valve 25 is pushed up by the fuel oil from the FMU 2, the fuel oil flows into the plunger chamber 21, and the plunger 4 When the ascending stroke is started, the inlet valve 25 is closed and the outlet valve 27 is pushed up by the pressurized fuel oil, so that the fuel oil is pumped from the fuel outlet 22.

As described above, the fuel supply pump 50 is
Fuel oil is supplied from a fuel tank 40 to a fuel metering unit (FMU) 2 by a feed pump 3, and the amount of fuel oil supplied to each plunger chamber 21 of the supply pump 1 is adjusted by the FMU 2. Fuel oil is supplied to the plunger chamber 2 through the valve 20.
1 and the fuel oil pressurized by the plunger 4 is fed from the fuel outlet 22 to the common rail 51 (see FIG. 6).

In the first embodiment, four cams 13 each having three cam ridges 14 are fixed to the camshaft 7, and two of the four cams 13 are cammed. The peaks 14 are made to be in phase, and the phases of the cam peaks 14 are shifted from each other between two groups when two cams 13 having the same phase are grouped.

As a result, when the camshaft 7 rotates, the cam peaks 14 of the two cams 13 simultaneously move to the top dead center as shown in FIG. 3, so that the pressurization of the fuel by the two plungers 4 is sequentially repeated. Thus, the pressurization of the fuel by the two plungers 4 is performed six times while the camshaft 7 makes one rotation. In this configuration, the product (12) of the number (4) of the plungers 4 and the number (3) of the cam ridges 14 is:
This is twice the number of cylinders (6) of the internal combustion engine.

At this time, the IO valve 2 communicates with the two plunger chambers 21 in which the plunger 4 has moved to the pressurizing position.
Since the zero inlet valve 25 is closed and the outlet valve 27 is open, the fuel pressurized in the plunger chamber 21 flows out of the fuel outlet 22 and is supplied to the common rail 51 (see FIG. 6). You.

The IO valve 20 communicates with the two plunger chambers 21 in which the plunger 4 has moved to the suction position.
Since the inlet valve 25 is open and the outlet valve 27 is closed, fuel flows from the FMU 2 into these plunger chambers 21.

According to the fuel supply pump 50 of the first embodiment, the fuel is pressurized by the two plungers 4 at the time of pressurizing the fuel. As compared with the case of pressurization, the oil supply capacity obtained in one pressurization time is approximately doubled. The product (12) of the number (4) of the plungers 4 and the number (3) of the cam lobes 14 is an integral multiple (2) of the number of cylinders (6) of the internal combustion engine.
), The fuel supply pump 50 sends the common rail 51
The fuel pressure is supplied to the combustion chamber a plurality of times, so that the decrease in the pressure in the common rail 51 due to the fuel injection into the combustion chamber can be effectively compensated.

Adjusting the cam 13 so that the cam peaks 14 have the same phase can use the same parts as the conventional fuel supply pump, and does not require a significant change in manufacturing equipment and the like. Therefore, it can be performed easily and at low cost.

Hereinafter, another embodiment of the present invention will be described with reference to the drawings. The same reference numerals are given to the same portions as those of the above-described first embodiment or portions having similar functions. The description is omitted.

In the fuel supply pump 50 according to the second embodiment of the present invention, as shown in FIG. 4, the camshaft 7 has the same three cam peaks 14 as those in the first embodiment. The six cams 13 are fixed, and three of the six cams 13 are set so that the cam peaks 14 are in the same phase. Thus, the phases of the cam peaks 14 are shifted from each other.

As a result, when the camshaft 7 rotates, the cam peaks 14 of the three cams 13 move to the top dead center at the same time, so that the pressurization of the fuel by the three plungers 4 is sequentially repeated, and the camshaft 7 becomes one. During the rotation, the fuel is pressurized by the three plungers 4 six times. In this configuration, the product (18) of the number (6) of the plungers 4 and the number (3) of the cam ridges 14 is three times the number of cylinders (6) of the internal combustion engine.

The IO valve 2 communicates with the three plunger chambers 21 in which the plunger 4 has moved to the pressurizing position.
Since the zero inlet valve 25 is closed and the outlet valve 27 is open, the fuel pressurized in the plunger chamber 21 flows out of the fuel outlet 22 and is supplied to the common rail 51 (see FIG. 6). You.

The IO valve 20 communicates with the three plunger chambers 21 in which the plunger 4 has moved to the suction position.
Since the inlet valve 25 is open and the outlet valve 27 is closed, fuel flows from the FMU 2 into these plunger chambers 21.

According to the fuel supply pump 50 of the second embodiment, the fuel is pressurized by the three plungers 4 at the time of pressurizing the fuel. As compared with the case of pressurization, the oil supply capacity obtained in one pressurization time is approximately tripled. The product (18) of the number (6) of the plungers 4 and the number (3) of the cam lobes 14 is an integral multiple (3) of the number of cylinders (6) of the internal combustion engine.
), The fuel supply pump 50 sends the common rail 51
The fuel pressure is supplied to the combustion chamber a plurality of times, so that the decrease in the pressure in the common rail 51 due to the fuel injection into the combustion chamber can be effectively compensated.

Further, for example, the conventional fuel supply pump (two plungers) shown in FIG. 7 and the fuel supply pump 50 (four plungers) according to the above-described first embodiment can be replaced with the second embodiment. In the case where the number of plungers 4 and the number of cams 13 are increased as in the case of changing to the fuel supply pump 50 (six plungers) according to the present invention, the parts such as the plunger 4, the plunger barrel 5, the cam 7, etc. Since the compatibility is maintained, it is possible to perform the operation relatively easily and at low cost without requiring a significant change in manufacturing equipment and the like.

Further, in the fuel supply pump 50 according to the third embodiment of the present invention, as shown in FIG. 5, six cams 13 are fixed to the camshaft 7. And
In the third embodiment, a cam 13 having two cam ridges 14 (not shown) is used.
Two of these six cams 13 are set so that the cam peaks 14 are in the same phase, and two
When the three groups are set as one group, the phases of the cam ridges 14 are shifted from each other among the three groups.

As a result, when the camshaft 7 rotates, the cam peaks 14 of the two cams 13 simultaneously move to the top dead center, and the pressurization of the fuel by the two plungers 4 is sequentially repeated. During the rotation, the fuel is pressurized by the two plungers 4 six times. Also,
In this configuration, the product (12) of the number (6) of the plungers 4 and the number (2) of the cam ridges 14 is twice the number of cylinders (6) of the internal combustion engine.

The IO valve 2 communicates with the two plunger chambers 21 in which the plunger 4 has moved to the pressurizing position.
Since the zero inlet valve 25 is closed and the outlet valve 27 is open, the fuel pressurized in the plunger chamber 21 flows out of the fuel outlet 22 and is supplied to the common rail 51 (see FIG. 6). You.

The IO valve 20 communicates with the two plunger chambers 21 in which the plunger 4 has moved to the suction position.
Since the inlet valve 25 is open and the outlet valve 27 is closed, fuel flows from the FMU 2 into these plunger chambers 21.

Also in the fuel supply pump 50 according to the third embodiment, the fuel is pressurized by the two plungers 4 at the time of pressurization. Can be improved. Further, the product (1) of the number (6) of the plungers 4 and the number (2) of the cam ridges 14 is obtained.
Since 2) is an integral multiple (2 times) of the number of cylinders (6) of the internal combustion engine, the fuel pressure is sent from the fuel supply pump 50 to the common rail 51 for one fuel injection into the combustion chamber. Is performed a plurality of times, it is possible to effectively compensate for a decrease in pressure in the common rail 51 due to fuel injection into the combustion chamber.

In the fuel supply pump 50 according to the first, second, and third embodiments described above, the number of the plungers 4 and the number of the cam ridges 14 formed on one cam 13 are determined. Is the number of cylinders of the internal combustion engine (6)
, The degree of freedom in designing the fuel supply pump can be improved. For example, even if an attempt is made to change the cam shape for the purpose of improving the oil supply capacity of the fuel supply pump 50, if there are restrictions such as strength and pump driving torque, the number of cams 13 (the number of plungers 4) is changed or This can be dealt with by changing the number of cam ridges 14 formed on one cam 13.

[0043]

As described above, according to the present invention, it is possible to provide a fuel supply pump having an improved oil supply capacity without significant changes in manufacturing equipment and the like. Further, it is possible to provide a low-cost fuel supply pump that can cope with a common rail system that requires particularly high pressure fuel.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of the fuel supply pump shown in FIG.
It is sectional drawing.

FIG. 3 is a schematic diagram showing a positional relationship of a plunger of the fuel supply pump according to the first embodiment.

FIG. 4 is a schematic diagram showing a positional relationship of a plunger of a fuel supply pump according to a second embodiment.

FIG. 5 is a schematic diagram showing a positional relationship of a plunger of a fuel supply pump according to a third embodiment.

FIG. 6 is a diagram showing a common rail system.

FIG. 7 is a sectional view showing a conventional fuel supply pump.

[Explanation of symbols]

 Reference Signs List 1 supply pump 2 fuel metering unit (FMU) 3 feed pump 4 plunger 5 plunger barrel 7 cam shaft 8 pump housing 13 cam 14 cam mountain 40 fuel tank 45 common rail system 50 fuel injection device (supply pump assembly) 51 common rail / Assembly 55 Injector assembly 57 Sensors 58 Electronic control unit

Continuation of the front page F term (reference) 3G066 AA07 AB02 AC09 AD02 BA54 CA01S CD28 CE04 3H070 AA02 BB03 BB07 BB25 CC21 DD35 3H075 AA03 BB03 CC25 DA04 DB04 DB24

Claims (3)

[Claims] 1. A camshaft which is rotationally driven by an internal combustion engine, a cam fixed to the camshaft and having a cam ridge, and a plunger which reciprocates along the shape of the cam. A fuel supply pump, comprising: two or more plungers, wherein the fuel is pressurized by at least two of the plungers at the time of pressurizing the fuel. 2. A product according to claim 1, wherein the product of the number of said plungers and the number of said cam ridges formed on one cam is an integral multiple of the number of cylinders of said internal combustion engine. Fuel supply pump. 3. The fuel supply pump according to claim 1, wherein the high-pressure fuel is supplied to a common rail.