JPS59173542A - Bifuel feed device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To ensure the maximum amount of main fuel to cover the entire operating range of an engine, by controlling the supply of auxiliary fuel to a fuel injection nozzle in accordance with the injection pressure of main fuel fed to another fuel injection nozzle, and as well by controlling the pressure-feed amount of auxiliary fuel from an auxiliary fuel device in accordance with the load and the engine speed. CONSTITUTION:Upon engine operation a computer unit 23 detects engine revolutions per a unit time in accordance with the output of a revolution sensor 20, and as well obtains the amount of load in accordance with the output of a position sensor 22 for detecting the position of a control rack in a fuel injection pump 3, so that it delivers, to an electrical current controller 24, a signal corresponding to the amount of auxiliary fuel in dependence upon the operating range of the engine. The rotational speed of an auxiliary fuel pump 5 is changed in accordance with an electrical current value from the electrical current controller 24, and therefore, the amount of fuel fed to an auxiliary fuel pressure-feed device 6 is also changed. Thereby the amount of fuel charged into an auxiliary fuel port 15 in a fuel injection nozzle 11 is changed. Main fuel is transferred to the fuel injection pump 3 by a main fuel pump 2, and then fed to a main fuel port 16 in the fuel injection nozzle 11.

Description

[Detailed description of the invention] Technical field The invention is directed to a dual fuel supply system for an internal combustion engine.

The device according to the present invention uses, for example, a non-compressible ignitable fuel (low cetane number) such as alcohol or gasoline, uses a fuel with excellent self-ignitability (high cetane number) such as light oil as an ignition source, and uses light oil as an ignition source such as alcohol, etc. It is used in internal combustion engines that inject the main fuel either before or at the same time as the main fuel.

Conventional technology In order to burn non-compression ignitable fuels (low cetane number fuels) such as alcohol and gasoline in compression ignition 43A engines, that is, diesel engines, it is necessary to use self-ignitable fuels (high cetane number fuels) such as light oil as the ignition source. ) It is necessary to inject the fuel (auxiliary fuel) into the engine cylinder before or at the same time as the non-compression ignitable fuel (main fuel). For this reason, a dual fuel supply device has been proposed that has a relatively simple configuration and is capable of injecting two different types of fuel from one injection nozzle.

FIG. 1 is a diagram of a conventional device. Main fuel is introduced from the main fuel tank 1 through a pipe 26 to the main fuel pump 2, is sent through a pipe 27 to the fuel injection pump 3, and is pumped to each It is injected into the engine cylinder from injection nozzles 11, 12, 13, and 14.

On the other hand, the auxiliary fuel is sent from the auxiliary fuel tank 4 to the pressure feeding device 6 by the auxiliary fuel pump 5, and is fed under pressure by the piston 7 and supplied to each nozzle 11, 12, 13, and 14. Here, the function of the pressure feeding device w6 for pressure feeding the auxiliary fuel will be explained. The auxiliary fuel sent by the auxiliary fuel pump 5 is checked by the check valve 9 and is kept in the pressure feeding device 6.

Further, the pressure feeding piston 7 is set to the pressure feeding pressure by a spring 8, and the main fuel branch point 38 is connected to the nonobu 29.
It is powered by the main fuel introduced by. The main fuel pressurized by the injection pump 6 overcomes the force of the spring 8, pushes the piston 7 upward, and pumps the auxiliary fuel to the nozzle 13.

The pressure-fed fuel is held between the injection nozzle 16 and the vibro 3 by the check valve 10.

On the other hand, the structure of the injection nozzle 11 includes a nozzle needle 17, a fuel hole 16 for main fuel that opens toward the nozzle tip in the direction of injection hole 18, and a fuel hole 15 for auxiliary fuel.

The piping connections between the pressure feeding device 6 and the injection nozzles 11, 12, 13 and 14 are very characteristic, and are arranged to take advantage of the injection order of a multi-cylinder engine. In other words, the phase is shifted every 180 CA, and the pressure of the main fuel of the 1st cylinder is connected to the pressure feeding device B connected to the 6th cylinder, the main fuel of the 6th cylinder is transferred to the pressure feeding device of the 4th cylinder, and so on. It has become.

Figure 2 shows each cylinder (floor 1 to positive 4) for the crank angle θ.
This is a time chart illustrating the change in the pressure inside the injection nozzle (P) at 0°.The pressure in the first cylinder increases at a crank angle of 0°, and after passing the valve opening pressure at Po, the main fuel flows from the injection nozzle for a time of tQ. Injected.

At the same time, the pressure of the auxiliary fuel pumping device connected to the third cylinder, which is the next injection cylinder, is also increased to Pl, which is the spring force within the pumping device, by the pressure of the main fuel in the first cylinder.
Auxiliary fuel is filled into the sixth cylinder nozzle.

Here, since the auxiliary fuel pressure P1 takes a lower value than the nozzle valve opening pressure PQ, the valve does not open, and remains at Pl during tl. Next, when the crank angle reaches 180°, the pressure of the main fuel in the 6th cylinder exceeds Po,
The needle in the nozzle lifts and the auxiliary fuel and main fuel are injected. Such a cycle is repeated in sequence according to the injection order, making it possible to supply multiple fuels of auxiliary fuel and main fuel.

Figure 6 explains the state of the spray from the injection nozzle, where the tip of the spray contains light oil, which is the auxiliary fuel F(S).
Alcohol, which is the main fuel (FCM), is sprayed behind it.

Figure 4 shows the relationship between time t and change in injection amount per unit time 6Q/dt, showing the timing of injection of auxiliary fuel light oil F(S) and main fuel alcohol F(M) It can be understood that this is done with a phase difference. Therefore, by injecting a small amount of light oil ahead of the alcohol, a flame is created by self-ignition of only the light oil, and the subsequent alcohol is injected toward the flame, making it easier to burn the alcohol. This makes it possible to operate on alcohol, which is a non-compressible ignitable fuel.

However, in actual operating conditions, that is, in a wide range of operating ranges, the conventional method limits the operable range. FIG. 5 shows its operating characteristics, and shows how the ignition range (FR) changes with light hydraulic pressure feed according to the conventional method.

In FIG. 5, the horizontal axis represents the engine speed N, the vertical axis represents the load W, PR represents the ignition region, M-PR represents the misfire region, and MAX represents the maximum output.

Now, L2 line (2A CIim'/5t-ayl)
) If the operating range shown by A (mi3/5t-cyl
)) When the operating range decreases to ), and conversely increases, L3
The operating range is expanded to line (6A (13/5 t-ayl)). In order to cover the entire operating range, it is sufficient to increase the amount of diesel oil supplied to the maximum extent possible, but this would mean that there is no point in using alcohol fuel, so it is necessary to supply the maximum amount of alcohol and ensure stable operating conditions. To achieve this, the amount of light oil supplied must be varied in accordance with the operating characteristic diagram shown in FIG.

In this way, in the conventional technology, the amount of light oil supplied is kept constant due to its structure, so if you try to secure the operating range,
If the amount of alcohol used decreases and an attempt is made to increase alcohol use, the driving range will be limited, and there is a problem in that securing the driving range and increasing alcohol use are not compatible.

Purpose of the Invention The purpose of the present invention is to detect the operating state of the engine using a rotational speed detection sensor and a load detection sensor, and compare it with the ignition operating range built into a microcomputer to provide optimal assistance. Based on the idea of controlling the auxiliary fuel system so that the amount of fuel is maintained, the aim is to cover the entire operating range while ensuring the maximum amount of main fuel.

Structure of the Invention In the present invention, an injection nozzle is provided with a main fuel boat and an auxiliary fuel boat that separately supply the main fuel and auxiliary fuel to the tip of the injection nozzle needle, a main fuel injection pump, and an injection nozzle other than the injection nozzle that supplies the auxiliary fuel. an auxiliary fuel pumping device that fills the injection nozzle below the valve opening pressure with the injection pressure of the main fuel; a rotation speed sensor that detects the rotation speed; a load sensor that detects the fuel supply amount of the main fuel;
There is provided an internal combustion @seki dual fuel supply system, comprising a calculation device that receives signals from the rotational speed sensor and the load sensor and generates a signal for controlling the pumping amount of the auxiliary fuel pumping device. Ru.

Embodiment A dual fuel supply system for an internal combustion engine as an embodiment of the present invention is shown in FIG. Reference numeral 1 indicates a main fuel tank, which is connected to the main fuel pump through a pipe 26, and after being pressurized, the main fuel is sent to the fuel injection pump 3 through a vibrator 27. The main fuel is pumped by the fuel injection pump 3 at a high pressure, usually 120ky/7 or higher, passes through the pipe 28 and the vibro 0, reaches the main fuel boat 16 of the injection nozzle 11, and then reaches the nozzle needle 1.
7゛ is pushed up and injected from the nozzle hole 18.

Since the device in Figure 6 is a 4-cylinder engine, there is one injection nozzle each.
1;, 12, 13, and 14 are connected to the injection pump 6. The auxiliary fuel is connected from the auxiliary fuel tank 4 to the auxiliary fuel pump 5 through a pipe 31, and after being pressurized is sent to the auxiliary fuel pumping device 6 via the vibro 2.

There is a branch point 38 between the main fuel pipe 28 and the pipe 30, and the main fuel is taken into the auxiliary fuel pressure-feeding bag w6 via the orifice 25 through the pipe 29 and is in contact with the piston 7. The piston 7 is pushed down by a spring 8, and when the main fuel overcomes the force of the spring 8, the piston rises and auxiliary fuel is pumped out. At this time, check valves 9, 10
As a result, the auxiliary fuel is pumped only to the injection nozzle 13.

A disk 19 having slits cut out at equal intervals is attached to the rotating shaft of the injection pump B, and a rotation speed sensor 20 detects the rotation speed of the engine. A position sensor 22 is attached to a control rack 21 that controls the injection amount of the injection pump 5, and a signal is inputted to a calculation device 23 through signal whips 34 and 35, respectively. A signal is output from the settlement device 23 to the current controller 24 via the signal line 36, and the auxiliary fuel pump 5 is operated under control via the signal line 67. As the calculation device 23, a four-microphone computer type device can be used.

The operation of the FIG. 6 apparatus is described below. When the engine is operated, the injection pump 3 also rotates in synchronization, and the disc 19 attached to the rotating shaft also rotates as indicated by the arrow AR1, causing the rotation speed sensor to generate an on/off voltage signal. This signal is counted by a reference clock in the calculation device 26 to detect the number of engine revolutions per unit time. Furthermore, the position of the control rack is known by a position sensor 22 installed opposite to the control rack 21 that controls the injection amount, and the calculation device 26 converts it into a load amount, and calculates the amount of auxiliary fuel according to the operating range shown in FIG. The current controller 24 outputs a signal corresponding to the calculation device 2 to the current controller 24.
A current value corresponding to the output signal No. 3 is transmitted to the auxiliary fuel pump 5 via the signal line 67, and the rotational speed of the auxiliary fuel pump 5 is changed to change the amount of supply to the auxiliary fuel pumping device 6. The amount filled into the auxiliary fuel boat 15 is changed.

In Figure 5, auxiliary fuel (light oil) for A (Dragon S/5t-cyl)
If the engine was operated in the ignition range of 2 A (fiN / 8 t, a
yl), and the calculation device 23 determines that the auxiliary fuel pump 5
The pump rotation speed is increased, and the amount of auxiliary fuel into the auxiliary fuel pumping device 6 is increased. The opposite operation occurs when the amount of auxiliary fuel is reduced due to a decrease in rotational speed and load.

An example of the operation of the computing device 26 in the device shown in FIG.
As shown in the flowchart of the figure.

In step 5100, the pulse signals of the start shift, the disc 19 and the rotation speed sensor 20 are input in step 5101,
In step 5102, the built-in reference clock generates a pulse P.
-P is counted, and in step 5103, the number of rotations per unit time No. is calculated. In step 5104, the engine rotation speed N is determined. It is determined whether or not is 0, and if it is 0, the engine does not rotate, so fuel is not injected, and the process returns to step 5101. Step 510
If N8 is other than 0 in step 4, that is, the engine is running, proceed to step 5105 and set the injection pump 5 control.
The signal from the position sensor 22 attached to the roller 21 is input, and in step 5106, the alcohol injection needle Q is read out from the R-Q table shown in FIG.

In Fig. 11, the horizontal axis is the alcohol injection amount Q (ad/5
t-cyl), the vertical axis is controllable, and the vertical axis is HR (
Hail mm). In step 5107, the engine speed N8 calculated in step 5103 is compared with the Nθ-Q table shown in FIG.
l).

In FIG. 10, the horizontal axis is the engine rotation speed N.

[-], and the vertical axis is alcohol injection kk Q (1111
/st・oil). Step 8108 reads the auxiliary fuel pump current value corresponding to the value of q from the q-1 table shown in FIG. 12, and outputs the 1 value to the current controller 24 in step 310.9.

In Figure 12, the horizontal axis is the minimum amount of light oil q (++4/st・
cyl), and the vertical axis shows the auxiliary fuel pump current (mA).

When one routine is completed as described above, step 51
10, the process returns to step 5100, and the engine speed and control rack signals are input again to repeat the control.

A dual fuel supply system for an internal combustion engine as another embodiment of the present invention is shown in FIG. Figure 7 shows the auxiliary fuel pumping device 6.
The bypass valve 41 controls the amount of auxiliary fuel supplied to the auxiliary fuel pump, and the pipe 32 between the auxiliary fuel pump 5 and the auxiliary fuel pumping device 6 is connected to the pipe 51 between the auxiliary fuel pump 5 and the auxiliary fuel tank 4. Pipes 42 and 43 are provided, and a bypass valve 41 detours a portion of the fuel supplied from the auxiliary fuel pump 5 to the auxiliary fuel pumping device 6 to control the amount of fuel supplied. The bypass valve 41 is driven by a solenoid 40, and the solenoid 40 is controlled by a solenoid drive device 39. 44 is a signal line.

An example of the operation of the computing device M23 in the device shown in FIG.
As shown in Figure 70-Chart.

Steps 8120 to 5127 are the same as the operation explained in FIG. 6 above. In step 5128, the bypass valve 41 is intermittently controlled by the solenoid 4o.
The duty ratio D is expressed as the ratio of the on-time t1 of the solenoid valve to the time t2 of one on-off cycle shown in FIG.
= t 1/12 is determined from the q-D table in FIG. 15, and the D value is output to the Tsuremade drive device in step s129.

In Figure 15, the horizontal axis is the minimum amount of light oil q (-/st, o
yl), and the vertical axis shows the duty ratio.

At step 5130, the process returns to step 5120 and the control is repeated.

A dual fuel supply system for an internal combustion engine as another embodiment of the present invention is shown in FIG. The device shown in FIG. 8 changes the lift amount of the piston of the pressure feeding device, and is auxiliary fuel feeding device 45.
The piston 50 has a wedge-shaped tip and is pressed downward by a spring 8. On the other hand, a stopper 51 facing the piston 50 also has a wedge-shaped tip, and is configured to rotate as indicated by an arrow AR4 by a ridge 52.

In addition, the controller 52 is a linear solenoid 56.
The movable iron piece 54 moves in the direction of arrow AR3 due to the balance between the spring 56 and the solenoid 55.

Furthermore, the solenoid 55 is connected to a solenoid drive device 57 by a signal line 58 so that it can be operated in accordance with the output signal of the calculation device 23 as appropriate.

Now, the movement of the piston 50 is 51c7]ml
The movement is determined and linked by the movement position, and is synchronized with the movement of the two 52. In other words, the rack 52 is the auxiliary fuel pumping device 45
When the piston 50 is pushed in toward the side, the effective stroke of the piston 50 decreases.
When pulled back to the side, the stroke increases and the amount of auxiliary fuel supplied can be controlled.

FIG. 8 shows an example of the operation of the computing device Wf23 in the device.
0 speed button 5140 shown in the flowchart of FIG.
~Step 3147G is the same as in the case of the previous statements 6 and 7. The movable iron piece 54 of the linear solenoid 56 moves with the rack 52 of the auxiliary fuel pressure bag @ 45, and by changing the current of the solenoid 55, the
51 can be rotated. Therefore step 8148
Then, a value of 1 is read out from the q-device shown in FIG. 12, and in step 5149, the solenoid drive device 57 outputs the current flowing to the linear solenoid 53, which can be changed.

Internal combustion ti! as another embodiment of the invention! The AI@ dual fuel supply system is shown in FIG. The device shown in FIG. 9 bypasses high-pressure fuel after the auxiliary fuel pressure feeding device 6, and connects the vibro 2° 63 and the bypass valve to the pipe 33 between the auxiliary fuel pressure feeding bag w6 and the injection nozzle 13 via a branch point 61. 5
9 is attached. The vibro 3 is connected to an auxiliary fuel tank 4 so that bypassed fuel is returned to the tank. Bypass valve 59 is driven by solenoid 60 and controlled by a signal from solenoid drive device 64 . That is, when reducing the supply amount, the solenoid 6o is turned on by a signal from the calculation device 23, the bypass valve 59 is opened, and the fuel in the pipe 33 is returned to the auxiliary fuel tank 4. The operation of the calculation device 23 in the device shown in FIG. 9 is similar to the operation of the calculation device 23 in the device shown in FIG.

Effects of the Invention According to the present invention, a non-compressible ignitable fuel such as alcohol,
When operating a compression ignition engine using gasoline as the main fuel, it is possible to cover the entire operating range while ensuring the maximum amount of main fuel.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional dual fuel supply device for an internal combustion engine, Fig. 2 is a diagram showing a time chart of the device in Fig. 1, and Fig. 3 is a diagram showing all states of the device in Fig. 1 in RTR4 mode. Figure 4 is the first
FIG. 5 is a diagram illustrating the characteristics of a dual fuel supply device. FIG. 6 is a diagram showing an internal combustion (8-speed dual fuel supply device) as an embodiment of the present invention. , FIG. 7, FIG. 8, and FIG. 9 are diagrams showing other embodiments of the present invention, FIG. 10, FIG. 11, and FIG. 12 are diagrams for explaining the operation of the device shown in FIG. 6, and FIG. is a flowchart diagram showing an example of the operation of the computing device in the device shown in FIG. 6, FIGS. 14 and 15 are diagrams for explaining the operation of the device shown in FIG. - Flowchart diagram showing an example, FIG. 17 is a flowchart diagram showing an example of the operation of the calculation device in the device shown in FIG. 8. (Explanation of symbols) 1... Main fuel tank, 2... Main fuel pump, 3...
- Injection pump, 4... Auxiliary fuel pump, 5... Auxiliary fuel pump, 6... Auxiliary fuel pressure feeding device, 7... Piston, 8... Spring, 9, 10... Check valve ,1
1, 12, 13° 14... Injection nozzle, 15... Auxiliary fuel boat, 16... Main fuel port, 17... Needle, 18... Nozzle hole, 19... Disc, 20 ...
Rotation speed sensor, 21... Control rack, 22.
... Position sensor, 23... Calculation device, 24... Current controller, 25... Orifice, 26° 27.28, 2
9,30,31,52.55...pipe, 34,55
, 56.37...signal line, 38...branch point, 39.
... Solenoid drive device, 40 ... Solenoid, 41
...Bypass valve, 42.43...Pipe, 44...
- Signal line, 45... Auxiliary fuel pressure feeding device, 50... Piston, 51... Stopper, 52... Rack, 55
... Linear remade, 54 ... Movable iron piece, 55.
... Solenoid, 56 ... Spring, 57 ... Solenoid drive device, 58 ... Signal line, 59 ... Binox valve, 60 ... Solenoid, 61 ... Branch point,
62.66...Pipe, 64...Solenoid drive device, 65...Signal line. Patent Applicant Toyota Motor Corporation Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Matsushita Akira Saidai, Kore 1 To → De θ Figure 5 11 → -N No. 6 Figure 91 Ka6, 5 - Ne No. 11 Q Page 12 → % No. 140 No. 15 -〉9

Claims (1)

[Claims] 1. An injection nozzle equipped with a main fuel port and an auxiliary fuel boat that separately supply the main fuel and auxiliary fuel to the tip of the injection nozzle needle, a main fuel injection pump, and an injection nozzle other than the injection nozzle that supplies the auxiliary fuel. An auxiliary fuel pumping device that fills the injection nozzle below the valve opening pressure with the injection pressure of the main fuel, a rotation speed sensor that detects the rotation speed, a load sensor that detects the fuel supply amount of the main fuel, and the rotation speed. A dual fuel supply system for an internal combustion engine, comprising a calculation device that receives signals from the sensor and the load sensor and generates a signal for controlling the pumping amount of the auxiliary fuel pumping device. 2. The device according to claim 1, wherein the control of the pumping amount of the auxiliary fuel pumping device based on the signal from the calculation device is performed in the form of control of the fuel amount before the auxiliary fuel pumping device. 6. The device according to claim 1, wherein the control of the pumping amount of the auxiliary fuel pumping device based on the signal from the calculation device is performed in the form of controlling the stroke of a pumping piston of the auxiliary fuel pumping device. 4. The device according to claim 1, wherein the control of the pumping amount of the auxiliary fuel pumping device based on the signal from the calculation device is performed in the form of controlling the pumping amount of the auxiliary fuel pumping device and thereafter.