JPH0235149B2 - NAINENKIKANNONENRYOFUNSHASEIGYOSOCHI - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to an internal combustion engine in which fuel injection timing, fuel injection amount, and fuel injection pressure can be easily adjusted without stopping the internal combustion engine and independent of the rotational speed of the internal combustion engine. The present invention relates to a fuel injection control device.

BACKGROUND ART In general, in internal combustion engines, particularly diesel engines, fuel injection timing has a large effect on internal combustion engine performance, particularly fuel consumption rate. In addition, the fuel consumption rate can be reduced by increasing the fuel injection pressure and shortening the injection period to increase combustion efficiency, but high-pressure injection when the internal combustion engine is under low load can cause diesel knock and cause the internal combustion engine to This causes strain on the internal combustion engine, leading to a shortened lifespan of the internal combustion engine and excessive noise. The optimal values for injection timing and pressure vary greatly depending on the operating conditions of the internal combustion engine and the quality of the fuel oil, so if the fuel injection timing and fuel injection pressure can be freely adjusted while the internal combustion engine is running, significant fuel savings can be achieved. This is possible without forcing the internal combustion engine to overdo it, and considering the current situation of soaring oil prices, it will generate large profits.

Conventionally, a fuel injection device for an internal combustion engine is configured by directly connecting a fixed stroke fuel injection pump that is driven in synchronization with the operation of the internal combustion engine and an automatic injection nozzle with a shutoff valve via a fuel injection pipe. Widely adopted around the world. In this conventional fuel injection device,
The fuel injection timing is determined by the cam setting position, and when changing the fuel injection timing, it is necessary to change the setting position of the cam on the camshaft, and the internal combustion engine must be temporarily stopped.

In order to solve this problem, the present applicant has already applied for patent application No. 57-42391 and patent application No. 57-42391.
According to the fuel injection device in -46619, a fuel control valve driven by a cam with an advance device is provided between the fixed stroke fuel injection pump and the automatic injection nozzle with a shutoff valve, By changing the connection timing of the passage between the valved automatic injection nozzle and the valved automatic injection nozzle using the cam with an advance device, the fuel injection timing can be adjusted without stopping the internal combustion engine. However, in such a device, the fuel injection pressure is determined by the rotational speed of the internal combustion engine and the dimensions of the injection nozzle, and cannot be freely adjusted.

On the other hand, in a fuel injection device already known in Japanese Patent Application Laid-Open No. 143344/1983, an injection nozzle with a shutoff valve is equipped with an electro-hydraulic servo valve, and the fuel flow path is switched using liquid pressure other than the fuel. Accordingly, the fuel stored in the high-pressure fuel source is injected into the cylinder from the injection nozzle, and the start and end of the injection is controlled by an electric pulse signal applied to the electrohydraulic servo valve. According to such a device, the fuel injection timing and fuel injection amount are determined by the transmission timing and pulse width of the electric pulse signal, and the fuel injection pressure is determined by the fuel pressure accumulated in the high-pressure fuel source. The injection timing, fuel injection amount, and fuel injection pressure can be freely adjusted regardless of the speed of the internal combustion engine or the installation of the cam. However, such devices require an expensive electro-hydraulic servo valve as well as a hydraulic power source to operate the valve, which increases the initial cost, and furthermore, electro-hydraulic servo valves are generally susceptible to contamination by impurities in the oil. Because it is weak,
There is a problem in that it is necessary to control dirt on the hydraulic oil, which increases operating costs.

In the above device, if an inexpensive and dirt-resistant solenoid valve is used instead of an electrohydraulic servo valve, the initial cost and operating cost can be reduced, but the cost is comparable to that of an electrohydraulic servo valve. A solenoid valve with such a response (for example, 1 ms) is not available.

Furthermore, when attempting to achieve high fuel injection pressure in the above three types of fuel injection devices, the strength of the components and connections on which the fuel injection pressure acts, such as the fuel injection pump, fuel injection pipe, and fuel injection valve, must be , which makes the equipment expensive.

In order to solve such prior art problems,
The inventor of the present invention proposed a fuel injection control device for an internal combustion engine shown in FIGS. 1 to 7.

FIG. 1 is a configuration diagram showing the basic configuration of the present invention previously proposed by the inventor of the present invention. The first pressure source 1 is connected to the fuel valve 3 via a solenoid valve 7 by a refueling line 38, and the second pressure source 2 is also connected to the fuel valve 3 via a control valve 4 by a control line 49. . The control valve 4 is driven by a cam 5 that moves in synchronization with the main shaft 6 of the internal combustion engine, and the solenoid valve 7 is controlled by an electrical signal from a control circuit 8. Each component will be explained in turn.

FIG. 2 is a sectional view showing the configuration of the fuel valve 3. As shown in FIG. This fuel valve 3 consists of a first part, a second part, and a third part, which are screwed together to form one fuel valve 3. That is, the first part is the lid 10, which is attached to the second part by bolts 14. A control hole 15 bored in the center of the lid 10 is connected to the control valve 4 via a control conduit 49. This control hole 1
A throttle member 19 and a check valve 20 are disposed inside the fuel valve 5, and the hydraulic fluid is configured to freely flow into the fuel valve 3 from the control conduit 49, but to be throttled when flowing out. .

The second part is a pump 11 driven by hydraulic pressure introduced through the control hole 15. The pump 11 has a servo piston 17, a pump piston 18, and a check valve 49 inside a casing 16. The pump piston 18 has an outer diameter larger than that of the servo piston 1.
The servo piston 17 and the pump piston 18 are operatively connected to each other. Therefore, the hydraulic pressure introduced into the servo pressure chamber 21 which is restricted by the upper surface of the servo piston 17 and the lid 10 is doubled by the cross-sectional area ratio of the servo piston 17 and the pump piston 18, and the pressure is increased by the lower surface of the pump piston 18. It acts on the pump chamber 33, which is restricted by this.

Note that the cross-sectional area of the flow path of the throttle member 19 installed inside the lid 10 is sufficiently small compared to the control hole 15 and the control conduit 49, and therefore the speed of oil discharge from the servo pressure chamber 21 can be regulated by the throttle member 19. It's getting old.
The time required for draining the oil must be selected such that t _M is sufficiently longer than the time t _E required for injection, but t _M +t _E is smaller than the time t _Z required for one cycle of the internal combustion engine. Since the amount of fuel filling the pump chamber 33, that is, the amount of fuel to be injected, is adjusted by adjusting the operating time of the solenoid valve 7, increasing the value of _tM helps improve control precision.

The third part is a well-known automatic injection nozzle 12 with a shutoff valve, in which a spring casing 22, a needle casing 23 and a nozzle 24 are wrapped around a cap nut 25, which is screwed into the lower part of the pump 11, that is, the casing 16. installed. A closing needle 27 is guided in the needle casing 23 , and the upper part 2 of this closing needle 27
A spring receiving plate 29 is fitted into the spring chamber 28 in the spring casing 22 at 7a. Located in the upper part of the spring chamber 28, the closing needle 27
A spring 31 is inserted between the spring receiver 30 that limits the opening stroke of the closing needle 2 and the spring receiver 29.
7 in the closing direction. A fuel reservoir 26 and a nozzle 24 are arranged in the lower part 27b of the closing needle 27.
7 to form a shutoff valve. fuel storage 2
6 communicates with a pump chamber 33 of the pump 11 via passages 36a and 36b formed in the spring casing 22 and the needle casing 23.

Inside the casing 16 of the pump 11, there is an oil supply hole 3.
4a, 34b are formed, one end of which is connected to a supply hole 35 provided in the lid 10,
The other end is connected to the pump chamber 33 via a recess 37 provided on the upper surface of the spring casing 22 . A check valve 46 is provided in the fuel supply hole 34 to prevent the fuel from flowing back into the fuel supply pipe 38 when the fuel is injected from the automatic injection nozzle 12, and to prevent the fuel from flowing back into the fuel supply pipe 38. can be filled into the pump chamber 33.

A passage 39 opening into the pump chamber 33 is formed inside the pump piston 18 and communicates with an annular passage 40 formed on the upper side surface of the pump piston 18 . These passages 39, 40 are located near the end of the downward stroke of the pump piston 18.
This effectively functions to drain the fuel in the pump chamber 33 to the supply side, thereby improving the so-called "draining" of the fuel. That is, one end of the horizontal hole 41 formed in the casing 16 opens upstream of the check valve 46 within the oil supply hole 34, and the other end can communicate with the annular passage 40.

The fuel leaked into the spring chamber 28 along the closing needle 27 is drained from the oil drain pipe 44 through the oil drain passage 42 and the oil drain hole 43 connected thereto to the tank 86 outside the fuel valve 3 (see FIG. 1). ). Fuel leaking along the servo piston 17 and the pump piston 18 is collected in an annular gap 45 formed slightly above the lower end of the vertical hole 32 into which the servo piston 17 is fitted. This annular gap 45
is open to the oil drain path 42.

As another configuration, a check valve (not shown) may be provided in the middle of the oil drain path 42. This check valve prevents the fuel once drained into the oil drain pipe 44 from flowing back into the annular gap 45 and the spring chamber 28, thereby preventing leaked fuel from interfering with the lowering of the servo piston 17. .

Note that an annular gap 4 is formed at a position where the pump piston 18 descends and collides with the spring casing 22, that is, slightly above the lower limit position of the servo piston 17.
5, the fuel sealed between the lower surface 32a of the vertical hole 32 and the inner surface of the servo piston 17 is compressed at the lower limit position of the servo piston 17.
The impact at the lower limit positions of the servo piston 17 and the pump piston 18 is alleviated (the third
(See figure) The maximum amount of fuel introduced into the pump chamber 33, that is, the maximum injection amount EV, is limited by the height of the protrusion 48 of the lid 10, so by changing this height, it can be applied to various internal combustion engines. , the maximum injection amount can be regulated. As another structure for regulating the maximum injection amount, an intermediate piece 47 may be provided between the servo piston 17 and the pump piston 18, and the length of this intermediate piece 47 may be selected.

Referring again to FIG. 1, the description of the components other than the fuel valve 3 will be continued. The first pressure source 1 includes a fuel conduit 5
0, is connected to the supply hole 35 of the fuel valve 3 via the solenoid valve 7 and the fuel supply conduit 38. First pressure source 1
is provided with a fuel tank 51, a fuel pump 52 that increases the pressure of the fuel from the fuel tank 51 and sends the fuel to the fuel conduit 50, and a pressure regulating valve 53 for keeping the fuel pressure in the fuel conduit 50 constant. It consists of In order to prevent pressure pulsations within the fuel conduit 50, an accumulator 54 may be provided in the middle of the fuel conduit. The electromagnetic valve 7 that controls the connection of the flow path between the fuel conduit 50 and the oil supply conduit 38 is driven by an electric signal from the control circuit 8. In other words, solenoid valve 7
The driving time becomes the metering time t _M , during which time the fuel valve 3
is filled with fuel. Since the filling rate is also affected by the viscosity of the fuel, the first pressure source 1 may be provided with a temperature control device (not shown) in order to improve metering control accuracy.

The second pressure source 2 is connected to the inlet hole 56 of the control valve 4 via a pressure conduit 55 and the outlet hole 57 of the control valve 4 is connected to the control hole 15 of the fuel valve 3 via a control conduit 49. . The second pressure source 2 is a tank 58
a booster pump 59 that boosts the pressure of the fuel from the tank 58 and sends the fuel to the pressure conduit 55; and a pressure control valve 60 that adjusts the pressure within the pressure conduit 55.
It is configured by providing. An accumulator 61 may be provided midway through the pressure conduit 55 to prevent pressure pulsations within the pressure conduit 55. The tank 58 is
This can be omitted by sharing the fuel tank 51 with the first pressure source 1 and the second pressure source 2.

In the control valve 4, a spool 63 is slidably and rotatably guided axially in the barrel 62 and is supported by a tappet 64. Barrel 62 and Tappet 64
A spring 65 is interposed between the spool 63 and the cam 5, and serves to press the spool 63 against the cam 5 via the roller 6. Spool 63 is driven by cam 5 against the force of spring 65 and connects pressure conduit 55 or return conduit 71 to control conduit 49. Note that the other end of the return conduit 71 is connected to the tank 58. The spool 63 has an axially oblique control line 67 and below the oblique control edge 67 is another control edge 68 perpendicular to the axial direction. This 2
A control groove 69 is formed facing the two control edges 67 and 68. On the other hand, the side surface of the barrel 62 has an inlet hole 56 connected to the pressure conduit 55, a return hole 70 connected to the return conduit 71, and a control conduit 4.
An outlet hole 57 connected to 9 is provided. The inlet hole 56 can be opened and closed by a diagonal control lip 67, and the return hole 70 can be opened and closed by a lower control lip 68.

Further, the outlet hole 57 is formed in the control groove 6 within the barrel 62.
It is always open at 9. In the state shown in the first figure, the outlet hole 57 communicates with the return hole 70 via the control groove 69. When the spool 63 moves axially, i.e. rises, the outlet hole 57 and the inlet hole 56
are in communication via the control groove 69, and the return hole 70 is closed. Fuel leaking along spool 63 is collected in cavity 74 inside barrel 62 and flows through passage 75 to return hole 70 . The air hole 76 at the bottom of the barrel 62 serves to reduce the driving force of the spool 63.

A pinion 72 is installed coaxially with the spool 63 below the control valve 4.
is sliding in the axial direction of the spool 63, but is coupled in the rotational direction, so that the spool 63 can be rotated by moving the latch 73 that meshes with the pinion 72. This rack 73 passes through the control valve 4 at right angles in the axial direction, and is connected to the control valve 4 via a drive device (not shown).
By operating the control valve 4, the operation timing of the control valve 4, that is, the fuel injection timing can be adjusted.

On the other hand, the cam shaft 77 to which the cam 5 is attached has a gear 78
a, 78b, 78c, 78d and chain 79
Although the camshaft 77 is driven by the main shaft 6 via the camshaft 79b, the method of driving the camshaft 77 is not essential to the present invention, and other methods may be used as long as the camshaft 77 is synchronized with the rotation of the internal combustion engine. .

In the case of an internal combustion engine consisting of multiple cylinders, the fuel conduit 5
0 branch pipes 50a, 50b, 50c, and pressure conduit 55 branch pipes 55a, 55.
Control valves 55b and 55c can be connected to each other in the same manner as shown in FIG. 1.

The first pressure source 1 is configured such that at least the servo piston 17 and the pump piston 18 are
requires enough pressure to push up against the frictional force. It is also conceivable to control the set pressure of the pressure regulating valve 53 in response to the rotation speed and/or load of the internal combustion engine. To change the set pressure, use a well-known positioner (not shown) to set the spring setting position of the pressure regulating valve 53, or provide a diagonal notch in the valve body of the pressure regulating valve 53 and rotate the valve body. Accordingly, the valve stroke at which the oil drain hole formed in the valve seat communicates with the notch may be changed.

The pressure of the second pressure source 2 defines the injection pressure of injection. For example, if the ratio of the diameters of the servo piston 17 and the pump piston 18 is 2.5:1, the pressure of the second pressure source 2 should be selected to be 200 atmospheres. If, 200×2.5 ²
= High pressure injection of 1250 atmospheres can be achieved. It is also conceivable to control the set pressure of the pressure regulating valve 60 in response to the rotation speed and/or load of the internal combustion engine. This works effectively to prevent diesel knock by lowering the injection pressure and therefore the fuel injection rate when the internal combustion engine is in a cold state. To change the set pressure, use a well-known positioner (not shown) to set the spring setting position of the pressure regulating valve 60, or provide a diagonal notch in the valve body of the pressure regulating valve 60 and rotate the valve body. Accordingly, the valve stroke at which the oil drain hole formed in the valve seat communicates with the notch may be changed.

Next, the operation of the configuration shown in FIGS. 1 to 3 will be explained. In the state shown in FIG.
Since the spool 63 of the fuel valve 3 is at the bottom dead center and the control conduit 49 is connected to the return hole 70 via the control groove 69, the servo pressure chamber 21 of the fuel valve 3 is at the bottom dead center.
(atmospheric pressure) and remains in the state shown in FIG. The pump chamber 33 is filled with fuel. As the cam 5 rotates and pushes the spool 63 up against the force of the spring 65 via the roller 66, the control edge 68 of the spool 63 closes the return hole 70, while the diagonal control edge 67 of the spool 63 closes the inlet hole. The hole 56 is opened, so that the outlet hole 57 of the control valve 4 and the inlet hole 56 communicate through the control groove 69 . Hydraulic oil (fuel oil) flowing into the pressure conduit 55 from the boost pump 59 of the second pressure source 2 flows into the control conduit 49 via the control valve 4 .

Referring to FIG. 2, the hydraulic oil flowing into the control conduit 49 flows into the control hole 15 of the fuel valve 3 and checks the check valve 2.
0 to the servo pressure chamber 21 and urges the servo piston 17 downward. Therefore, the pump piston 18, which is arranged to interact with the servo piston 17, is also urged downward and compresses the fuel filled in the pump chamber 33, so that the pressure of the fuel in the pump chamber 33 increases. Serpo piston 17
Since the outer diameter of the pump piston 18 is larger than the outer diameter of the pump piston 18, the pressure in the servo pressure chamber 21 is doubled by the cross-sectional area ratio, which acts on the pump chamber 33. The fuel pressurized in the pump chamber 33 does not flow back into the fuel supply hole 34 because the check valve 46 is interposed therebetween.
6a and 36b, the fuel flows to the fuel reservoir 26 of the automatic injection nozzle 12 with a well-known shutoff valve, and is injected from the nozzle 24 into a cylinder (not shown).

The pump piston 18 descends due to fuel injection,
When the state shown in FIG. 3 is reached, the pump piston 18
An annular passage 40 and a horizontal hole 41 formed on the side surface communicate with each other. The fuel in the pump chamber 33 flows from the passage 39 in the pump piston 18 to the fuel supply hole 34 via the lateral hole 41. Then, the pressure of the fuel in the pump chamber 33 drops rapidly, so that the fuel that was injected into the cylinder (not shown) from the automatic injection nozzle 12 with a shutoff valve is stopped by the shutoff needle 27 biased by the spring 31. It is then shut off and the injection ends. The profile of the cam 5 is designed so that the inlet hole 56 and the outlet hole 57 of the control valve 4 communicate with each other until the fuel injection is completed. For example, in the case of a four-cycle internal combustion engine with an injection period of 35 degrees in crank angle at maximum load, the spool 63 of the control valve 4 is connected to the return hole 7.
If we consider the period from closing the 0 to opening the inlet hole 56, that is, the so-called switching margin, to be about 10 degrees when converted into a crank angle, a cam with a crank angle of about 45 degrees is required, and the entire cam width is The ratio to the circumference is approximately 45 degrees/720 degrees = 1/16.

As the cam 5 continues to rotate and passes the top dead center, the spool 63 pulls the spring 65 along the profile of the cam 5.
The control valve 4 finally switches the passage between the control valve 4 and the second pressure source 2.
That is, the spool 63 is lowered so that the diagonal control edge 67 of the spool 63 closes the inlet hole 56, while the control edge 68 of the spool 63 opens the return hole 70. As a result, the outlet hole 57 and the inlet hole 56, which were communicating through the control groove 69, are cut off, and the outlet hole 5
7 and the return hole 70 communicate with each other via the control groove 69, the hydraulic oil in the servo pressure chamber 21 in the fuel valve 3 flows to the tank 58 via the return conduit 71, and the servo pressure chamber 21 is at atmospheric pressure. Become.

When the solenoid valve 7 is excited by the electric signal sent from the control circuit 8, the fuel in the first pressure source 1 is
From the fuel conduit 50 to the fuel supply conduit 38 via the solenoid valve 7
and is supplied to the fuel valve 3. Referring again to FIG. 2, fuel flowing from the fuel supply conduit 38 to the supply hole 35 flows into the pump chamber 33 via the check valve 46. Some of the fuel bypasses the non-return valve 46 and flows into the pump chamber 33 through the lateral hole 41, the annular passage 40 and the passage 39 until the lateral hole 41 is blocked by the side of the pump piston 18.

The fuel flowing into the pump chamber 33 urges the pump piston 18 upward, and the pump piston 18 and the servo piston 17 connected thereto are pushed up against the frictional force. Serpo piston 17
Hydraulic oil, which has been removed in the servo pressure chamber 21 due to the rise of
It flows to 8. Although fuel also flows through the automatic injection nozzle 12 communicating with the pump chamber 33, no injection occurs because the pressure of the first pressure source 1 is lower than the opening pressure of the automatic injection nozzle 12 (for example, 200 atmospheres).

The electric signal from the control circuit 8 is cut off and the solenoid valve 7
When the pump is demagnetized, the fuel flowing from the first pressure source 1 to the fuel valve 3 via the fuel conduit 50 and the fuel supply conduit 38 is cut off, the upward stroke of the pump piston 18 is stopped, and the state shown in the first diagram is returned. . While the electromagnetic valve 7 is energized in this way, the fuel filled in the pump chamber 33 becomes the amount of fuel to be injected in the next cycle. And the maximum amount is the intermediate piece 47
Since it is determined by the length of the valve and the height of the protrusion 48, the maximum injection amount can be regulated according to the scale of the internal combustion engine, and even if the solenoid valve 7 fails, a torque that would destroy the internal combustion engine will not be generated.

The throttle member 19 functions to regulate the rate at which fuel is filled into the pump chamber 33, and is useful for improving the accuracy of controlling (metering) the amount of fuel filled. That is, the aperture member 1
If metering is performed slowly using valve 9, accurate metering becomes possible, and the high responsiveness (for example, 1 ms) of electromagnetic valve 7 is not required. For example 1000rpm
In the case of a 4-cycle internal combustion engine with an injection period of 35 degrees at a crank angle, the injection time t _E is t _E = 35/6 x 1000 = 5.8 ms, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 143344/1983. If this period _tE is to be directly controlled by a solenoid valve, the responsiveness of the solenoid valve must be at least 0.5 ms, and the only option is to use an electro-hydraulic servo valve. However, according to the metering structure according to the present invention, the adjustment time is
Since t _M only needs to be completed within one cycle, t _M ≦60×2/1000−t _E = 114.2 ms, and a response of about 10 ms is sufficient, eliminating the need for an electro-hydraulic servo valve. It becomes possible to measure the amount using a solenoid valve that is resistant to dirt and is inexpensive.

In order to regulate the filling speed of fuel into the pump chamber 33, the structure in which a throttle member is provided on the oil discharge side of the pump 11 as in the present invention has the following advantages compared to the structure in which a throttle member is provided on the inflow side. It is excellent in several respects.
That is, in the latter structure, the aperture member 19 is connected to the control hole 1.
Although this structure is provided inside the fuel supply hole 34 instead of in the fuel supply hole 5, this structure is susceptible to disturbances when metering the fuel, and there is a limit to the improvement of control accuracy. This will be explained below with reference to FIG. The relationship between various quantities related to the pump 11 can be expressed by the following group of equations.

P ₁・A ₁ + (A ₂ −A ₁ )Pm=P ₂・A ₂ +F …(1) ΔP ₁ =P ₀ −P ₁ =K ₁・Q ₁ …(2) ΔP ₂ =P ₂ =K ₂・Q ₀ …(3) Q ₁ /A ₁ =Q ₀ /A ₂ …(4) Here, A ₁ ; Cross-sectional area of pump piston 18 A ₂ ; Cross-sectional area of servo piston 17 P ₀ ; First pressure Pressure of source 1 (constant) P ₁ ; Pressure of pump chamber 33 P ₂ ; Pressure of servo pressure chamber 21 Pm; Pressure of oil drain path 42 F; Frictional force of pump operation Q ₁ ; Filling flow rate Q ₂ ; Drain flow rate K ₁ ; Flow path resistance on the inflow side K ₂ ; Flow path resistance on the drain side. However, the tank pressure is assumed to be 0, and the pressure of the first pressure source 1 is assumed to be constant. Now, assuming that the flow path resistance on the inflow side and oil discharge side is constant (K ₁ , K ₂ = constant), the filling speed Q ₁ into the pump chamber 33 is determined by the differential pressure ΔP ₁ ,
Since P ₀ is adjusted constant, it is dominated by P ₁ (second equation). Also, the speed of oil discharge from the fuel valve 3
Since the filling speed Qi is determined even if Q ₀ is specified (the fourth
Similarly, Qi is defined by P ₂ (3rd equation).
Therefore, if P ₁ or P ₂ is kept constant, the filling speed can be regulated to a constant value, but since the frictional force F associated with the pump operation and fluctuations in the pressure Pm in the oil drain passage 42 act as disturbances. P ₁ and P ₂ vary (first
(Formula), even if the operating time of the solenoid valve 7 is specified as _tM , the filling amount will change. In order to reduce the influence of such disturbances, P ₁ and P ₂ may be increased. That is,
Transforming the first equation, P ₂・A ₂ + {F−(A ₂ −A ₁ )Pm}=P ₁・A ₁
...(1a), if P ₂ · A ₂ >>F-(A ₂ -A ₁ )Pm ...(5), the influence of the disturbance (the second term on the left side of equation 1a) can be ignored. P ₁ without changing the dimensions of the fuel valve 3,
To increase P ₂ , either increase P ₀ or
There are two possible options: or increasing K ₂ .
If P ₀ is increased, the filling speed Q ₁ will be increased, resulting in a disadvantage that the metering time t _M will be shortened. This is because the longer the metering time _tM is, the more accurate the metering can be. Therefore, the metering time
In order to reduce the influence of disturbance without shortening _tM , it is sufficient to increase _K2 . If K ₁ is further reduced, P ₁ also becomes larger. As mentioned above,
Eliminating the throttle member on the inflow side and arranging the throttle member on the oil drain side is more effective in improving metering control accuracy.

The sending timing of the electric signal that excites the solenoid valve 7 can be controlled by attaching an angle detector (not shown) to the camshaft 77 shown in FIG. . The pulse width of the electric signal sent from the control circuit 8 is determined by a known control device (not shown) that compares a rotation speed meter (not shown) attached to the main shaft 6 with a command signal (not shown), and increases or decreases the pulse width depending on the magnitude of the comparison. For example, a PI control device, etc.) may be used.

The timing at which fuel is injected from the fuel valve 3, that is, the fuel injection timing, can be adjusted by operating the rack 73. If you operate Rack 73,
As the pinion 72 rotates, the spool 63 also rotates and therefore the diagonal control edge 67
The amount of lead between the inlet hole 56 and the inlet hole 56 changes, and the inlet hole 56
Since the opening timing of the fuel injection valve can be controlled, fuel injection timing can be controlled even when the internal combustion engine is operating. Further, by driving the rack 73 via a drive device (not shown) depending on the rotational speed and/or load of the internal combustion engine, it is possible to operate at an optimum fuel consumption rate according to the rotational speed and load.

In yet another configuration, if the control edge 68 is provided parallel to the oblique control edge 67, it is possible to prevent negative pressure in the control groove 69 during the upward stroke of the spool 63, thereby preventing the control valve from becoming negative. The force driving 4 can be reduced. However, such a spool is more expensive to manufacture than the spool 63 shown in FIG.

Regarding the fuel injection pressure in this configuration,
Since it is determined by the pressure of the hydraulic oil in the servo pressure chamber 21, by adjusting the pressure of the second pressure source 2, the injection pressure can be adjusted without depending on the internal combustion engine rotation speed like in conventional injection devices. It is possible to choose freely. This improves the economy and operability of the internal combustion engine. Further, the pressure of the hydraulic oil in the second pressure source 2 is doubled inside the fuel valve 3 by the cross-sectional area ratio of the servo piston 17 and the pump piston 18 and the fuel is injected.
1200 atm) can be easily and inexpensively achieved. In other words, the pressure resistance of the second pressure source 2, control valve 4, pressure conduit 55, and control conduit 49 may be small (for example, 350 atm), and sealing methods and pipe joints for each part do not require special development, and can be done using conventional methods. technology can be used as is.

FIG. 5 is a configuration diagram showing another configuration as the basis of the present invention previously proposed by the inventor of the present invention, and parts corresponding to the above-mentioned configuration are given the same reference numerals. This configuration differs from the previous embodiment in that a flow meter 87 is disposed in the middle of the fuel conduit 50. In the above-described configuration, the filling speed is regulated by the throttle member 19, but the speed depends on the temperature of the fuel and the first pressure source 1.
Even if the pulse width of the electric signal from the control circuit 8 is the same, there will be a slight difference in the amount of fuel filled. The signal from the flowmeter 87 is given to the control circuit 8, and by limiting the maximum pulse width of the electrical signal sent from the control circuit 8 in response to the signal from the flowmeter 87, unexpected or undesirable signals can be detected. This makes it possible to prevent a relatively large amount of fuel from being injected into the cylinder. That is, the flow meter 87 cooperates with the control circuit 8 to realize a torque limit of the internal combustion engine and prevent overload from occurring. In addition to the flowmeter 87, a thermometer may be provided in the middle of the fuel flow pipe 50, and this signal may be connected to the control circuit 8 to further correct the density.

FIG. 6 is a sectional view showing another configuration of the fuel valve 3. The configuration of the fuel valve 3 shown in the second figure differs in the shape of the throttle member, and in this embodiment, the throttle member 88 is formed by a thin-bladed orifice. Although the throttle member 19 of the above-described embodiment is excellent in terms of life and strength, it has the disadvantage that the viscosity changes when the temperature of the fuel oil changes, so the filling rate changes. According to the thin-blade orifice adopted in this example, although the strength is inferior, the filling rate does not change depending on the temperature of the fuel oil.

FIG. 7 is a sectional view showing still another configuration of the fuel valve 3. What is noteworthy about this configuration is that a position detector 89 is provided inside the casing 16. As mentioned above, since the filling speed is affected by the temperature of the fuel and the pressure of the first pressure source 1, there is a limit to the control accuracy of the injection amount in the configuration shown in the second figure. According to this configuration, the position detector 89
The signal from is given to the control circuit 8. By controlling the pulse width of the electric signal according to the signal from the position detector 89, it is possible to precisely adjust the injection amount to the desired value, regardless of the fuel temperature or the pressure of the first pressure source 1. becomes.

Furthermore, as another configuration, the pump 11 and the injection nozzle 12 are integrally constructed, but a structure may be adopted in which the pump 11 and the injection nozzle 12 are separated and connected by an injection pipe.

Generally, the fuel injection pattern, ie, the time course of the injected fuel flow rate, provides the heat generation pattern within the cylinder. The heat generation pattern determines the pressure pattern within the cylinder, which has a significant impact on fuel efficiency. Specifically, if fuel is injected all at once at top dead center and combusted instantly, the maximum engine efficiency can theoretically be achieved. At this time, the pressure inside the cylinder becomes extremely large and exceeds the strength limit of the engine. Generally, if the heat generation period is shortened, fuel efficiency will improve, but on the other hand, the pressure in the cylinder will increase. In order to withstand large cylinder pressures, the engine must be made robust, which increases manufacturing costs.

FIG. 14 is a graph for explaining the operation of the configuration described in relation to FIGS. 1 to 7. Fig. 14 1 shows the time course of the fuel flow rate injected from the fuel valve 3 into the combustion chamber of the internal combustion engine, and Fig. 14 2
indicates the time course of the pressure inside the cylinder, that is, the pressure inside the fuel chamber. As is clear from FIG. 14, in the configurations shown in FIGS. 1 to 7, the duration of the maximum pressure P10 in the cylinder (see FIG. 14, 2) is short;
Therefore, efficiency, ie fuel consumption, is poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection control device for an internal combustion engine that allows maximum efficiency, ie, fuel efficiency, to be obtained under a specified engine strength.

In the present invention, the pump piston 18 of the fuel valve 3 is driven by a servo piston 17 having a larger diameter, and the pump chamber 33 defined by one end surface of the pump piston 18 is connected to the automatic injection nozzle 12 with a shutoff valve. and the first pressure source 1 supplies fuel to the pump chamber 33 via the solenoid valve 7, while
A spool 63 driven in the axial direction by a cam 5 that moves in synchronization with the internal combustion engine is connected between the second pressure source 2 and a servo pressure chamber 21 defined by one end surface of the servo piston 17 in the fuel valve 3. The spool 63 is connected to a control valve 4 having a spool 63 whose angular displacement can be adjusted around the axis, and the control valve 4 is in a first switching position when the servo pressure chamber 21 of the fuel valve 3 is connected from the outlet hole 57 to the return hole. 70 to drain the fuel, and in the second switching position of the control valve 4,
The fuel of the second pressure source 2 is transferred from the inlet hole 56 to the outlet hole 5.
7, a control groove 6 that supplies the servo pressure chamber 21
9 is formed in the barrel 62, the inlet hole 56 is formed at one location in the circumferential direction of the barrel 62 of the control valve 4, and the spool 63 of the control valve 4 has two front control holes diagonally with respect to the circumferential direction. A front control groove 102 having edges 100 and 101 spaced apart in the axial direction is formed, and the spool 63 includes the front control groove 102 and the control groove 6.
A communication hole 103 communicating with 9 is formed,
When the flow path to the servo pressure chamber 21 is switched from the return hole 70 to the inlet hole 56, the servo pressure chamber 21 and the second
The flow path to the pressure source 2 is temporarily interrupted by a collar 104 formed between the front control groove 102 of the spool 63 and the control groove 69, and the period of filling of the pump piston 18 is interrupted by the electromagnetic This fuel injection control device for an internal combustion engine is characterized in that it can be controlled by a valve 7 and the filling speed can be regulated by throttle members 19 and 90.

FIG. 8 is a sectional view of the control valve 4 according to an embodiment of the present invention. The configuration other than the control valve 4 is shown in Figures 1 to 7.
The configuration is the same as that shown in the figure. The eighth in this example
In the illustrated control valve 4, a front control groove 102 having two front control edges 100, 101 obliquely formed in the spool 63 with respect to the circumferential direction is formed, and cooperates with an inlet hole 56 connected to the second pressure source 2. Thus, when the spool 63 rises, the connection between the inlet hole 56 and the outlet hole 57 is temporarily interrupted. Note that the spool 63 is provided with a communication hole 103 that connects the front control groove 102 and the control groove 69.

Next, the operating state of this embodiment will be explained.
In the control valve 4 shown in FIG. 8, the outlet hole 57 and the return hole 70 communicate with each other via a control groove 69, and the front control edge 100 of the spool 63 closes the inlet hole 56. The front control groove 102 facing the two front control edges 100 and 101 communicates with the control groove 69 via the communication hole 103. When the spool 63 moves upward, the control lip 68 closes the return hole 70.

On the other hand, since the front control edge 100 opens the inlet hole 56, the inlet hole 56 is connected to the two front control edges 100, 101.
The front control groove 102 facing the front side communicates with the control groove 69 via the communication hole 103. For this reason, the pressure conduit 55
The hydraulic oil from the second pressure source 2 that has reached the inlet hole 56 via the control groove 69 flows into the outlet hole 57, reaches the servo pressure chamber 21 of the fuel valve 3 via the control introduction pipe 49, and then enters the servo piston 17. is pressed down, and injection occurs as described in the previous configuration.

When the spool 63 rises further, the front control groove 1
02 and the control groove 69
4 closes the inlet hole 56, so the inlet hole 56
The hydraulic oil flowing from the control groove 69 to the control groove 69 is temporarily cut off. As a result, the lowering of the servo piston 17 of the fuel valve 3 is also temporarily interrupted, and as a result, the injection is also stopped. However, when the spool 63 rises further, the inlet hole 56 that had been closed by the collar 104 opens, so the blocked hydraulic oil flows to the outlet hole 57 again, and the injection is restarted.

During the period when the jet slope is interrupted, the pre-control groove 10
2 and the control groove 69, that is, the length between the front control edge 101 and the control edge 67. At this time, the fuel injection is divided into two stages as shown in FIG. 9, with a short pre-injection followed by a long main injection. It goes without saying that the amount of fuel is adjusted based on the total value of the pre-injection and the main injection. FIG. 12 is a graph for explaining the operation in the embodiment shown in FIG. 12th
FIG. 1 shows an injection pattern showing the time course of the fuel flow rate injected by the fuel valve 3, and FIG.
is a graph showing the time course of the pressure in the cylinder,
The graph in FIG. 12 corresponds to the graph in FIG. 9 described above. In the present invention, by adjusting the fuel injection pattern shown in FIG. 12, the maximum pressure P11 in the cylinder (see FIG. 12, 2) can be adjusted.
can be suppressed within the limits of the engine strength, and moreover, better effects can be obtained. For example, the front control groove 102
If the length of the top and bottom in Figure 8 is shortened, the first
3. The pressure pattern in the cylinder shown in FIG. 1 can be realized. Further, by shortening the length of the front control groove 102 and shortening the length between the front control edge 101 and the control edge 67, that is, the length of the collar 104, the pressure pattern in the cylinder shown in FIG. 132 is obtained. be able to. Furthermore, by increasing the length of the pre-control groove 102, the pressure pattern in the cylinder shown in FIG. 13 can be realized.

The pre-injection followed by the main injection as shown in the embodiment of FIG. 8 is useful for increasing the combustion efficiency in medium-speed or high-speed internal combustion engines, and the effect is particularly significant in high-speed internal combustion engines.

Furthermore, in the present invention, if the rack 73 is configured to be able to be operated independently for each cylinder, it becomes possible to adjust the fuel injection timing for each cylinder, and to correct imbalances in load and combustion pressure between cylinders, stop the internal combustion engine. It also has the advantage that it can be corrected without any trouble.

In the embodiments described above, the throttle member is built into the fuel valve 3, but the throttle member may be arranged in the control valve 4 or the return conduit 71 in other embodiments of the present invention. FIG. 10 is a configuration diagram showing the basic configuration of the present invention in which a throttle member 90 is disposed in the middle of the return conduit 71. Return the aperture member 90 to the hole 7
If it is screwed to 0, the installation cost can be reduced. In such an embodiment, the fuel valve 3 would be as shown in FIG. 11, and the throttle member and check valve would be unnecessary.

As described above, according to the present invention, it is possible to easily adjust the fuel injection timing for each cylinder without temporarily stopping the internal combustion engine.
It becomes possible to adjust the injection amount and injection pressure. Since the pump piston 18 of the fuel valve 3 is driven by the servo piston 17 having a larger diameter, the injection pressure can be made high. Furthermore, fuel injection can be temporarily stopped and interrupted to improve combustion conditions.

Furthermore, according to the present invention, since the throttle members 19 and 90 are provided on the fuel discharge side, the pressure in the pump chamber 33 of the fuel valve 3 can be made high, and therefore the influence of frictional force etc. can be increased. Precise metering is possible without overloading.

Furthermore, according to the invention, the spool 63 of the control valve 4 is formed with two front control edges 100, 101, so that the flow path from the return hole 70 to the inlet hole 56, i.e. 2 pressure source 2
When switching to , the flow path between the servo pressure chamber 21 and the second pressure source 2 is temporarily cut off. Therefore, the fuel injection operation consists of a short pre-injection followed by a long main injection. This makes it possible to increase fuel combustion efficiency in medium-speed or high-speed internal combustion engines, and the effect is particularly remarkable in high-speed internal combustion engines. Further, according to the present invention, the control valve 4 performs the pre-injection and the subsequent main injection as shown in FIG. This makes it possible to enhance the combustion effect of the fuel. That is, according to the present invention, it is possible to set the fuel injection pattern so as to generate high pressure in the cylinder for a long period of time while limiting the maximum pressure in the cylinder.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the basic structure of the present invention, FIG. 2 is a cross-sectional view showing the fuel valve 3, FIG. 3 is a cross-sectional view showing the pump piston 18 shown in FIG. 2 in a lowered state, and FIG. The figures are diagrams for explaining the principle of the configuration shown in Figures 1 to 3, Figure 5 is a configuration diagram showing another configuration that is the basis of the present invention, and Figure 6 is a diagram showing another configuration of the fuel valve 3. 7 is a cross-sectional view showing still another configuration of the fuel valve 3, FIG. 8 is a cross-sectional view showing one embodiment of the control valve 4 according to the present invention, and FIG. 9 is a cross-sectional view showing an embodiment of the control valve 4 according to the present invention. A graph showing the relationship between time and pressure in fuel injection in an example, FIG. 10 is a configuration diagram showing still another basic configuration of the present invention, and FIG.
12 is a graph for explaining the operation of the present invention, and FIG. 13 is a graph showing the fuel injection pattern of another operation of the present invention.
FIG. 4 is a graph for explaining the operation of the prior art. 1...First pressure source, 2...Second pressure source, 3...
Fuel valve, 4... Control valve, 5... Cam, 7... Solenoid valve, 12... Automatic injection nozzle, 17... Servo piston, 18... Pump piston, 19, 90...
... Throttle member, 21 ... Servo pressure chamber, 33 ... Pump chamber, 56 ... Inlet hole, 62 ... Barrel, 63
... Spool, 67, 68, 84 ... Control edge, 7
1...Return conduit.

Claims (1)

[Claims] 1. The pump piston 18 of the fuel valve 3 is driven by a servo piston 17 having a larger diameter, and the pump chamber 33 defined by one end surface of the pump piston 18 is an automatic injection nozzle with a shutoff valve. 12
, the first pressure source 1 supplies fuel to the pump chamber 33 via the solenoid valve 7, while the second pressure source 2 and the servo piston 17 in the fuel valve 3
A control valve 4 having a spool 63 driven in the axial direction by a cam 5 that moves in synchronization with the internal combustion engine between the control valve 4 and the servo pressure chamber 21 defined by one end surface.
is connected to the spool 63, and the spool 63 is adjustable in angular displacement around the axis, and the control valve 4 is in the first switching position when the servo pressure chamber 21 of the fuel valve 3 is injected with fuel from the outlet hole 57 through the return hole 70. is drained, and in the second switching position of the control valve 4,
The fuel of the second pressure source 2 is transferred from the inlet hole 56 to the outlet hole 5.
7, a control groove 6 that supplies the servo pressure chamber 21
9 is formed in the barrel 62, the inlet hole 56 is formed at one location in the circumferential direction of the barrel 62 of the control valve 4, and the spool 63 of the control valve 4 has two front control holes diagonally with respect to the circumferential direction. A front control groove 102 having edges 100 and 101 spaced apart in the axial direction is formed, and the spool 63 includes the front control groove 102 and the control groove 6.
A communication hole 103 communicating with 9 is formed,
When the flow path to the servo pressure chamber 21 is switched from the return hole 70 to the inlet hole 56, the servo pressure chamber 21 and the second
The flow path to the pressure source 2 is temporarily interrupted by a collar 104 formed between the front control groove 102 of the spool 63 and the control groove 69, and the period of filling of the pump piston 18 is interrupted by the electromagnetic A fuel injection control device for an internal combustion engine, characterized in that the fuel injection control device can be controlled by a valve 7 and the filling speed can be regulated by throttle members 19 and 90.