JPH05272427A - Fuel injector - Google Patents

Abstract

PURPOSE:To miniaturize a fuel injector in compact size and realize low vibration, low noise and low NOx performance. CONSTITUTION:A rotary cylinder type or rotary cam type multiple axial plunger pump P1 is used as a fuel injecting pressure source for an internal combustion engine. The number of plungers disposed in the multiple axial plunger pump P1 is the same as that of cylinders of the corresponding internal combustion engine. An injector 1 and a plunger 2 for each cylinder correspond one to one to each other, to be connected therebetween via a pipeline. A pressure intensifying mechanism A capable of increasing a pressure on the basis of an area ratio of a large diameter portion to a small diameter portion is disposed in the vicinity of or integrally with the injector 1. An electronic control mechanism D is provided in a circuit of the pressure intensifying mechanism A, for changing over injection by a discharge pressure from a multiple plunger pump and injection under pressure increased by the pressure intensifying mechanism A, and controlling an injection timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art Conventionally, a technique using an improved distributed fuel injection device for reducing vibration noise and NOx of a diesel engine has been known. For example, JP-A-2-277955 and JP-A-3-13844.
No. 6, JP-A-4-5466, and JP-A-3-5466.
The technique is disclosed in Japanese Patent No. 85366 and Japanese Patent Laid-Open No. 3-124957.

Further, the fuel pressure discharged from the fuel injection pump is increased by a pressure increasing mechanism and supplied to the injector,
The technology of high-pressure injection is also known. For example, JP-A-63-170556 and Japanese Utility Model Laid-Open No. 2-9.
This is the same as the technique described in JP-A-0358, JP-A-61-261653, and JP-A-58-216459.

[0004]

SUMMARY OF THE INVENTION The present invention provides a fuel injection device that takes into account both the advantages of the above-described conventional row-type or distribution-type fuel injection device and the advantages of the fuel injection device with a booster mechanism. It is a thing. In particular, the fuel injection pump is a rotary type multi-plunger pump, and is configured as a plunger rotary type or a cam rotary type. As described above, by making the fuel injection pump a rotary type, it is possible to eliminate the long fuel injection pump cam shaft used in the conventional row-type fuel injection device and to make it compact. The fuel injection pump for each injector is provided in a one-to-one correspondence.

A pressure boosting mechanism is provided between each fuel injection pump and the injector, and the pressure boosting mechanism is controlled by an electronic control mechanism so that each injector has the best timing and injection amount. Is controlled so that the injection can be performed. Therefore, depending on the operating condition of the engine,
With the pressure boosting mechanism in a non-pressurized state, injection can be performed with the injection pressure of the fuel injection pump as it is, or high pressure injection can be performed via the pressure boosting mechanism, which reduces vibration noise and reduces NOx. Is intended.

[0006]

The problems to be solved by the present invention are as described above, and the means for solving the problems will be described below. That is, a rotary cylinder type or a rotary cam type,
A multi-axial plunger pump is used as a fuel injection pressure source for an internal combustion engine.

Further, the number of plungers of the multi-plunger pump is made to correspond to the number of cylinders of the corresponding internal combustion engine, the injectors 1 and the plungers 2 of the cylinders are made to correspond one to one, and the two are connected by piping. It is a thing.

Further, a pressure increasing mechanism A for increasing the pressure in accordance with the area ratio of the large diameter portion and the small diameter portion is provided in the vicinity of the injector 1 or integrally with the injector 1.

Further, an electronic control mechanism D for controlling the switching between the injection by the discharge pressure from the multi-plunger pump and the injection increased by the pressure increasing mechanism A, and the injection timing is interposed in the circuit of the pressure increasing mechanism A. It is a thing.

[0010]

[Operation] Next, the operation will be described. That is, the rotary type fuel injection pump is provided with the number of plungers corresponding to each cylinder, and the pressure increasing mechanism A corresponding to the number of cylinders is used.
Also, an accumulator is provided if necessary. Further, since the electronic control mechanism D and the three-way control valve V, which can be switched between the case of injecting through the pressure boosting mechanism A and the case of injecting by the pressure of the fuel injection pump, are provided, depending on the operating state of the engine. Injecting the discharge pressure of the fuel injection pump from the injector 1 is also controlled by the electronic control mechanism D.
It is also possible to switch the one-way control valve V and inject by the pressure increased by the pressure increasing mechanism A, so that low vibration, low noise, and low NOx performance are obtained.

[0011]

EXAMPLES Next, examples will be described. FIG. 1 is a hydraulic circuit diagram of a fuel injection device composed of a rotary cam type multi-axial plunger pump and a pressure increasing mechanism A, FIG. 2 is an overall perspective view of the rotary cam type multi-axial plunger pump, and FIG. Side cross-sectional view of a multi-axial plunger pump of a rotary type, FIG. 4 is a hydraulic circuit diagram of a fuel injection device composed of a rotary cylinder type multi-axial plunger pump and a pressure increasing mechanism A, and FIG. 5 is a rotary cylinder type multi-axial plunger pump. Cross section of the
6 is a sectional view showing an overflow mechanism for adjusting the discharge amount of the rotary cam type multi-axial plunger pump, FIG. 7 is a side view showing the shape of the pump drive cam 5, and FIG. It is drawing which shows the shape of a cam surface.

This will be described with reference to FIG. The feed pump 12 suctions and discharges from the fuel tank 17, and supplies the fuel oil to the rotary cam type multi-axial plunger pump P1. The multi-axial plunger pump P1
Is composed of a pump case 10 and a plurality of plungers 2 fitted in axial cylinder holes formed in the pump case 10. The numbers of the plungers 2 and the axial cylinder holes are configured to correspond one-to-one with the number of cylinders of the internal combustion engine. The pump case 10 is fixed in the case of the multi-axial plunger pump P1, and the plunger 2 also maintains the same position.

The plunger 2 is in the same position,
It follows the unevenness of the rotating pump drive cam 5 to move back and forth, suck the fuel oil in the axial cylinder hole from the suction valve 16, and then discharge it from the discharge valve 13. A contact roller or a ball 15 is interposed between the plunger 2 and the pump drive cam 5 to minimize the frictional force generated between the plunger 2 and the pump drive cam 5.
The cam shaft 11 of the pump drive cam 5 rotates, and the concavo-convex portion of the pump drive cam 5 causes the contact roller or the ball 15 at the tip of the plunger 2 to move back and forth, so that each plunger 2
Each time, the fuel is discharged in order.

From the number of discharge valves 13 corresponding to each cylinder,
Fuel is discharged toward each cylinder, and a pressure increasing mechanism A, an accumulator 4, a three-way control valve V, and an electronic control mechanism D are configured for each discharge valve 13. Therefore, in the case of four cylinders, four sets of pressure increasing mechanism A and accumulators 4 and 3 are used.
The one-way control valve V and the electronic control mechanism D are prepared.

The electronic control mechanism D receives signals from the crank angle sensor and the load sensor, and controls the injection timing and injection amount to be the optimum injection timing and injection amount determined according to the state of the engine. That is, in a special case such as at the time of starting, the three-way control valve V is closed by a command from the electronic control mechanism D, and the fuel oil discharged from the discharge valve 13 is supplied from the check valve 14 to the multi-axial plunger pump P1. It is injected with the discharge pressure as it is. Therefore, in this case, since the discharge oil does not reach the large diameter cylinder 9 of the large diameter piston 6 of the pressure increasing mechanism A, the high pressure by the small diameter piston 7 is not generated.

When the internal combustion engine starts to operate at high speed after starting, the valve is opened by a signal from the electronic control mechanism D. As a result, the pressure oil from the discharge valve 13 is stored in the accumulator 4 and flows into the large diameter cylinder 9 of the large diameter piston 6. Further, a part of the fuel oil from the discharge valve 13 is also supplied from the check valve 14 to the small diameter cylinder 8 of the small diameter piston 7, the pressure is increased by the area ratio of the large diameter piston 6 and the small diameter piston 7, and the inside of the small diameter cylinder 8 is The fuel oil is pressurized and discharged from the injector 1.

In the above structure, the discharge flow rate of the fuel injection pump is adjusted in the case of the multi-axial plunger pump P1 as shown in FIG. This is done by providing the oil passage 2a and changing the positional relationship with the overflow oil passage 10a in the sleeve provided in the pump case 10. Therefore,
All plungers 2 connected to multiple injectors 1
Similarly, a mechanism for adjusting the discharge flow rate is provided.

In the case of a rotary cam type multi-axial plunger pump, the operating surface of the pump drive cam 5 contacting the contact roller or the ball 15 provided on the head of the plunger 2 has a gradient shape during one rotation. , Is determined in accordance with a predetermined injection rate change (plunger speed change).
After the internal combustion engine starts operating, the electronic control mechanism D
By adjusting the switching timing of the valve according to the signal from, it is configured to achieve low vibration, low noise, and low NOx.

A feed pump 12 is connected to the fuel supply side of the multi-axial plunger pump P1. Further, one discharge valve 13 is provided for each plunger on the discharge side of the fuel injection pump. Further, the pressure increasing portion switching mechanism is a three-way control valve system that switches between connecting the large diameter piston 6 side of the pressure increasing portion to the discharge side of the fuel injection pump or opening it to the tank side. And this 3
The electronic control mechanism D is used for the switching method of the one-way control valve V.

Depending on the injection pressure, without using the booster,
The discharge pressure of the fuel injection pump can be directly introduced into the injector 1. In this case, the divided flow of the fuel oil for each cylinder, which is discharged from the multi-axial plunger pump P1, is directly injected from the injector 1.

2 and 3, the structure of the multi-axial plunger pump P1 is disclosed. In this embodiment, the suction valve 16 is arranged inside the plunger 2, and the discharge valve 13 is housed in the discharge port. Therefore, fuel is fed into the plunger 2 through the feed pump 1
It can flow in from 2 through the suction valve 16.

The shape of the pump driving force 35 is configured as shown in FIGS. In this embodiment, since it is necessary to rotate the pump drive cam 5, the cam shaft 11 is a rotating shaft. However, as shown in FIGS. 4 and 5, in the case of the rotary cylinder type multi-axial plunger pump P2, the side of the pump case 10 rotates and the plunger 2 and the contact roller or the ball 15 also rotate, so that the pump drive cam The side of 5 does not rotate.

Next, description will be made with reference to FIGS. 4 and 5. In the case of the rotary cylinder type multi-axial plunger pump P2, the pump case 10 is supported by the pintle shaft 22 and the rotary drive shaft 19 so as to be rotated.
On the contrary, the pump drive cam 5 does not rotate, but is rotatable about the pump drive cam rotation shaft 18 by a certain angle in order to adjust the pump discharge amount.

The rotation of the rotary drive shaft 19 and the pintle shaft 22 causes the pump case 10 to rotate.
The plunger 2 fitted in the cylinder hole of the pump 2 moves back and forth at the portion contacting the pump drive cam 5, and the fuel oil sucked from the feed pump 12 through the suction valve 16 is drilled in the pintle shaft 22. The oil is discharged to the discharge valve 13 via the passage and the portion of the circumferential oil passage of the pintle shaft 22.

As described above, when the rotary cylinder type multi-axial plunger pump P2 is used, the amount of oil discharged can be adjusted by rotating the pump drive cam 5 about the pump drive cam rotation shaft 18 to move the plunger 2 out. This is possible by adjusting the amount of withdrawal. The fuel oil discharged from the discharge valve 13 is guided to the pressure increasing mechanism A, the cylinder, and the three-way control valve V. The pressure increasing mechanism, the electronic control mechanism, the accumulator, and the control mechanism using the three-way control valve V are the same as those in FIG.

A rotary cam type pump provided with a swash plate type rotary cam can be used. The change in the flow rate during one rotation of the pump shaft in this case is the same as in the case of the rotary cylinder, but the point that flow rate control and overflow control is different from the case of the rotary plunger type. The pressure increasing mechanism, the electronic control mechanism, the accumulator, and the control mechanism using the three-way control valve V are the same as those in FIG.

[0027]

Since the present invention is configured as described above, it has the following effects. That is, as in claim 1,
Since the rotary cylinder type or rotary cam type multi-axial plunger pump is used as the fuel injection pressure source of the internal combustion engine, the fuel injection pump can be configured in a tubular shape, and the conventional cams arranged in parallel on the rotary cam shaft are used. As a result, it is possible to make the size smaller than that of the row-type fuel injection pump configured to move the plungers in parallel with each other. Further, the pump case 10 can be made compact, and the entire fuel injection pump can be made compact.

The number of plungers of the multi-plunger pump is made equal to the number of cylinders of the corresponding internal combustion engine, the injectors 1 and the plungers 2 of the cylinders are made to correspond one to one, and the two are connected by piping. Therefore, the plunger 2 and the injector 1 can be made to correspond to each cylinder similarly to the conventional row-type fuel injection device, so that electronic control can be performed for each cylinder, resulting in low vibration, low noise, and low noise. NOx
It became easy to control.

Further, since the pressure increasing mechanism A for increasing the pressure in accordance with the area ratio of the large diameter portion and the small diameter portion is interposed near the injector 1 or integrally with the injector 1, the discharge pressure from the normal fuel injection pump is provided. Further, since it is possible to inject from the injector 1 while being pressurized by the pressure increasing mechanism A, low N
It was possible to realize Ox conversion. Further, since the pressure increasing mechanism A is provided for each cylinder, the control between each fuel injection pump and the injector 1 can be completely performed independently.

Further, switching between injection by the discharge pressure from the multi-plunger pump and injection increased by the pressure increasing mechanism A, and an electronic control mechanism D for controlling the injection timing, injection amount, injection rate Since it is installed in the circuit of No. 3, it can be guided to the pressure increasing mechanism A by the three-way control valve V to increase the injection pressure of the injector 1 and reduce NOx in a long operating state after the start. Therefore, it can contribute to the protection of the environment.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a fuel injection device including a rotary cam type multi-axial plunger pump and a pressure increasing mechanism A.

FIG. 2 is an overall perspective view of a rotary cam type multi-axial plunger pump.

FIG. 3 is a side sectional view of a rotary cam type multi-axial plunger pump.

FIG. 4 is a hydraulic circuit diagram of a fuel injection device configured by a rotary cylinder type multi-axial plunger pump and a pressure increasing mechanism A.

FIG. 5 is a sectional view of a rotary cylinder type multi-axial plunger pump.

FIG. 6 is a sectional view showing an overflow mechanism for adjusting the discharge amount of a rotary cam type multi-axial plunger pump.

FIG. 7 is a side view showing the shape of a pump drive cam 5.

FIG. 8 is a drawing showing the shape of the cam surface of the pump drive cam 5.

[Explanation of symbols]

A pressure increasing mechanism P1 rotary cam type multi-axial plunger pump P2 rotary cylinder type multi-axial plunger pump D electronic control mechanism V 3-way control valve 1 injector 2 plunger 4 accumulator 5 pump drive cam 6 large diameter piston 7 small diameter piston 8 small diameter Cylinder 12 feed pump

Claims (4)

[Claims] 1. A fuel injection device comprising a rotary cylinder type or rotary cam type multi-axial plunger pump as a fuel injection pressure source for an internal combustion engine. 2. The fuel injection device according to claim 1, wherein
The number of plungers of the multi-plunger pump is made to match the number of cylinders of the corresponding internal combustion engine, and the injector 1 for each cylinder is
The fuel injection device is characterized in that the plungers 2 and the plungers 2 are connected in a one-to-one correspondence, and the two are connected by piping. 3. The fuel injection device according to claim 2,
A pressure increasing mechanism A for increasing the pressure in the vicinity of the injector 1 or integrally with the injector 1 by the area ratio of the large diameter portion and the small diameter portion.
A fuel injection device characterized by being installed. 4. The fuel injection device according to claim 3,
An electronic control mechanism D for controlling the injection by the discharge pressure from the multi-plunger pump and the injection increased by the pressure increasing mechanism A and controlling the injection timing is interposed in the circuit of the pressure increasing mechanism A. Fuel injection device.