JPS6149139A - Diesel engine with supercharger - Google Patents

Abstract

PURPOSE:To improve a response characteristic of acceleration, by providing an injection rate control mechanism variably controlling a fuel injection rate and a control device controlling the injection rate control mechanism when an engine is accelerated. CONSTITUTION:A fuel injection nozzle 10 provides an injection rate control mechanism 35 variably controlling a fuel injection rate. The nozzle 10 arranges the end of a plunger member 36 oppositely facing to a piston part 33a and applies the pressure of fuel from a fuel introducing port 26 acting on the rear end surface of the member 36. A control device 44 controls the nozzle 10 in such a manner that leak fuel is discharged only by the first fuel discharge passage 37 by closing a solenoid operated opening and closing valve 39 when an engine is accelerated from its low speed operation or the engine is low load operation while the leak fuel is discharged both by the first and second fuel discharge passage 37, 38 by opening the solenoid operated opening and closing valve 39 when the engine is accelerated from its high speed operation or the engine is in intermediate load operation. In this way, a response characteristic of acceleration can be improved by expediting a rise of the supercharger pressure in the initial time of acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a supercharged diesel engine equipped with a supercharger that supercharges intake air using exhaust energy, and particularly to measures for improving acceleration response.

<Prior Art> A pressure supercharger has been known as one type of supercharging system that supercharges intake air using exhaust energy (see Japanese Patent Publication No. 38-1153). This pressure supercharging system consists of a rotor that is rotatably supported within a case and has a large number of partition walls arranged radially to form a large number of small chambers, and an air intake inlet formed in the case at one end of the rotor. and an intake outlet, and an exhaust inlet and an exhaust outlet formed in the case on the narrow end side of the rotor, and as the rotor rotates, the intake air drawn into the small chamber of the rotor from the intake inlet is On the other hand, exhaust gas is caused to flow into the small chamber from the exhaust gas inlet, and the intake air is compressed and accelerated due to the pressure difference between the two, and is then discharged from the intake and discharge ports. In other words, the pressure wave energy of the exhaust gas is transferred to the intake air, and while the intake air is supercharged, the exhaust air remaining in the small chamber is discharged from the exhaust outlet, and the intake air 2j
The air is repeatedly scavenged by introducing intake air into the small chamber from the i inlet.

(Problem to be Solved by the Invention) However, when accelerating a diesel engine equipped with supercharging as described above, the temperature of the exhaust passage decreases due to low-temperature exhaust gas at low rotation speeds before acceleration. , thermal energy loss occurs in the exhaust gas flowing into the supercharger during acceleration, and the supercharging pressure does not rise immediately at the beginning of acceleration, resulting in a delay in response. In particular, in order to effectively transmit exhaust energy to the intake air in the supercharger, if an exhaust surge tank is provided in the exhaust passage upstream of the supercharger to suppress and alleviate exhaust pulsation in each cylinder, E: air passage As the capacity of J increases, the thermal energy loss mentioned above increases, so either d or f of the acceleration response mentioned above increases.

Therefore, the present invention has been made in view of this point, and its purpose is to increase the exhaust energy at the early stage of acceleration to increase the supercharging pressure when the J5 diesel engine is equipped with supercharging as described above. The purpose is to improve acceleration response by performing it immediately.

In order to achieve the above-mentioned object ((b1) of the invention), the solution of the present invention is to supercharge the intake air by exhaust energy.
In addition to providing an injection rate control mechanism that makes the fuel injection rate variable in the supercharged diesel engine, the fuel injection rate becomes smaller during acceleration.J: Sea urchin injection heavy equipment 1
It was designed to have a number of formations and fortifications to control the 211.

(Function) With the above configuration, in the present invention, at 7+[l speed, fuel 1'
By controlling the 81 injection Ω dimension to be small, the injection period becomes longer at the beginning of acceleration, promoting 1!2 combustion and increasing exhaust energy. Therefore, the supercharging pressure will be reduced by 1" immediately.

(Example) Hereinafter, embodiments of the present invention will be explained based on the drawings.

In FIG. 1, 1 is a four-cylinder diesel engine, and 2 is an upstream end that is open to the atmosphere, and a downstream end that is open to each cylinder of an engine 1 via branch passages 2a to 2d to supply intake air to each cylinder of the engine 1. The upstream end of the supply intake passage 3 is a branch passage 3
This is an exhaust passage that opens into each cylinder of the engine 1 via 8 to 3d, and whose downstream end opens to the atmosphere to discharge exhaust gas from each cylinder of the engine 1.

4 is a pressure wave supercharger disposed across the intake passage 2 and exhaust passage 3, and driven by the engine 1 via a belt transmission and a transverse shaft 5 of 11λ. As is well known, the pressure wave supercharger 4 has a rotor rotatably supported within a case, and a number of partition walls are arranged radially around the outer circumference of the rotor, and the partition walls extend around the outer circumference of the loaf. A large number of small pieces are formed in the circumferential direction. An intake inlet 6J5 and an intake discharge lower are formed in the case at one end of the rotor. The pressure wave supercharging units 1 and 2 are connected to the downstream side of the pressure wave supercharging units 1 and 4, respectively. Further, an exhaust inlet 8 and an exhaust outlet 9 are formed in the case at the other end of the rotor, and these are connected to the upstream side d5 and the downstream side of the pressure wave supercharger 4 of the exhaust passage 3, respectively. However,
As the rotor rotates, high-pressure exhaust gas flows into the small chamber in which low-pressure intake air is trapped through the air inlet 8. The pressure difference generates a pressure wave (compression 'fj shock wave) that flows inside the small chamber. By propagating the pressure wave energy of the exhaust gas into the intake air, the intake air is compressed and accelerated and discharged from the intake/discharge lower, supercharging the intake air, and then the exhaust gas flowing into the small chamber is transferred to the exhaust discharge port. 9, and the intake air is introduced into the small chamber from the intake air inlet 6 to scavenge the exhaust air (R).

Further, 10.10... are bottle-type fuel injection nozzles arranged in each cylinder of the engine 1, and 11 is driven by the engine 1 via the belt transmission II t#ff12, and the fuel injection nozzle 10.10 13 is an air-cooled intercooler installed downstream of the pressure wave supercharger 4 in the intake passage 2, and 13 is an air-cooled intercooler that supplies fuel from the pressure wave supercharger 4 to The high temperature intake air is cooled by heat exchange with outside air (driving wind). Reference numeral 14 denotes a first air cleaner with a coarse opening provided upstream of the pressure wave supercharging 15M4 of the intake passage 2, and the intake inlet 6 of the pressure wave supercharger 4 is connected to the atmosphere through the first air cleaner 14. I try to communicate with them. A second air cleaner 15 is provided in the intake passage 2 downstream of the pressure wave supercharger 4 and upstream of the intercooler 12, and is finer than the first air cleaner 14. It communicates with the engine 1 via a second air cleaner 15.

Roughly speaking, 16 indicates each branch passage 3a to 3 in the exhaust passage 3.
The exhaust surge tank 17 is installed downstream of the pressure wave supercharger 4 in the exhaust passage 3. It is filtered by the first air cleaner 14 with coarse mesh, and the pressure wave supercharging is carried out at a pressure of, for example, 60 to 80μ to avoid damaging the first air cleaner 14.
After removing the above dust, the air is sucked into the pressure wave supercharger 4 through the intake air inlet 6, and the intake air is heated in the pressure wave supercharger 4 by transmitting the pressure wave energy of the exhaust gas to the intake air (intake air). Pressure and discharge from the intake/discharge lower.

Next, this pressurized intake air is filtered through a second air cleaner 15 with fine mesh to remove particles of, for example, less than 20μ so as not to impede engine performance. Cool engine 1 to an appropriate temperature.
The air is inhaled into each cylinder. After that, the exhaust gas discharged from each cylinder of the engine 1 is suppressed and alleviated in the exhaust pulsation of each cylinder in an exhaust surge tank 16, and then is caused to flow into a pressure wave supercharging system from an exhaust system 9 and a pressure wave supercharging system 4. J5 in the supercharger 4 transmits pressure wave energy to the intake air, and then it flows out from the exhaust outlet 9, and after reducing exhaust noise with a silencer 17, it is released into the atmosphere.

In addition, in the intake passage 2, the pressure wave supercharging R4 is upstream, the first air cleaner 14 is downstream, the pressure wave supercharger 4 is downstream, and the second air cleaner 15 is upstream. They are communicated by a bypass passage 18, and a one-sided valve 19 is interposed in the middle of the intake bypass passage 18 to allow intake air to flow from upstream to downstream of the intake bypass passage 18 and prevent reverse flow. At the same time, the downstream end frontage of the intake bypass passage 18 has a downstream end frontage J: the intake bypass passage 18 for the intake passage 2 downstream of the rim or the intake passage 2 upstream of the downstream end frontage.
A switching valve 20 is provided to selectively switch the communication between the switching valve 20 and the switching valve 20, which is switched and controlled by a starting detecting means 21 made of bimetal or the like that detects when the engine is starting. 21, the switching valve 20 is switched so that the intake passage 2 upstream of the downstream end opening is closed and the intake bypass passage 18 and the intake passage 2 downstream of the downstream end opening are communicated with each other. 4 The upstream intake air is not sucked into the pressure wave supercharging lA4, but is passed through the intake bypass passage 18 to cause pressure wave overflow Na lX14.
A starting valve device 22 is configured in which a bypass flow is made downstream, thereby reducing the engine load at the time of starting and ensuring good starting performance.

Further, in the exhaust passage 3, the pressure wave supercharging 14
The exhaust surge tank 16 downstream and the pressure wave supercharger 4 downstream and the silencer 1 upstream communicate with each other via an exhaust bypass passage 23 so as to bypass the pressure wave supercharger 4. A wastegate valve 24 that opens the exhaust bypass passage 23 is interposed in the middle of the exhaust bypass passage 23, and when the pressure (supercharging pressure) in the intake passage 2 downstream of the pressure wave supercharger 4 exceeds a set value, the wastegate valve 24 opens the exhaust bypass passage 23. By opening the valve 24 and opening the exhaust bypass passage 23, pressure wave supercharging (pressure wave supercharging is performed through the exhaust bypass passage 23 without allowing the upstream exhaust gas to flow into the pressure wave supercharger 4). Machine 4
By bypassing the flow downstream, the supercharging pressure is lowered and maintained at the maximum set supercharging pressure value, thereby preventing damage to the engine 1 due to an abnormal increase in the supercharging pressure.

The structure of the fuel injection nozzle 10 will be explained based on FIG. 2.
In the fuel hole facing the combustion chamber of each cylinder, the Q hole 25 is located on the rear end side (
The fuel inlet port 26 connected to the fuel injection pump 11 is provided with a nozzle body 27 on the upper side of the same side, and a cylinder 28° spring chamber is arranged in order from the rear end side to the front end side of the nozzle body 27. 2, needle valve support hole 30
and a fuel pressure chamber 31 are formed, and these cavities are provided coaxially with the fuel inlet 26 and fuel injection hole 25 and in communication with each other. The chamber 31 (combustion hole 25) is connected to the fuel passage 32 formed in the nozzle body 27.
l has been used. Roughly speaking, a needle valve 33 is fluid-tightly supported in a needle valve support hole 30 and fitted in the cavity from the cylinder 28 to the fuel injection hole 25 so as to be openable.
Three needle valves 33 have a piston part 33a disposed in the forward side of the cylinder 28, a spring receiving part 33b arranged in the spring chamber 29, etc. pressure receiving part 33c receiving fuel pressure, etc.
A valve portion 33d that opens and closes the fuel injection hole 25 and the fuel injection hole 2
and a throttle part 33e disposed within 5,
A certain gap is formed between the throttle portion 33e and the wall surface of the fuel injection hole 25. Further, a nozzle spring 34 for urging the needle valve 33 in the valve closing direction is compressed in the two spring chambers, and the fuel injection pump 1
1 is burnt through the fuel passage 32 from the fuel inlet 26] When the high pressure fuel is introduced into the pressure air 31, the needle valve 33 is activated by the nozzle spring due to the action of the fuel pressure on the pressure receiving part 33c of the needle valve 33. The valve is closed against the biasing force of the needle valve 34, and the fuel is burned and injected into the combustion chamber of the engine through the nozzle hole 25.
The throttle part 33e and fuel injection hole 25 depending on riX.
The structure is such that the lift of the needle valve 33 and the opening area of the fuel nozzle hole 25 change as the gap between the fuel injection hole and the fuel injection hole changes. In other words, in the needle valve 33, after the quantity valve, first the throttle part 33c is located in the combustion lever hole 25, and the opening area of the fuel injection hole 25 is approximately constant due to the throttle part 33e17) of the fuel injection hole 25. The throttle part 33e moves out from the fuel nozzle hole 25, and the throttle part 33e moves out from the fuel nozzle hole 25 to move to a proportional change range where the frontage area of the fuel nozzle hole 25 increases in proportion to the lift concavity of the needle valve 33. then it will be lifted to the full lift position.

The fuel injection nozzle 10 is provided with an injection heavy equipment control 311 mechanism 35 that makes the fuel injection rate variable.

That is, the plunger member 36 is inserted into the rear side of the cylinder 28 so as to be freely movable once by a predetermined stroke by engaging an engagement groove 36a formed on the outer circumferential surface of the plunger member 36 with a protrusion 28a formed on the side wall of the cylinder 28. has been done. That is, the plunge V member 36 is freely disposed on the rear end side of the needle valve 33 on the same level as the needle valve 33,
The tip of the plunger portion vi36 faces the piston portion 33a, which is the rear end portion of the needle valve 33, and is configured such that fuel pressure from the fuel 26 acts on the rear end surface.

A fuel pressure chamber 31 is located on the side wall of the cylinder 28 (nozzle body 27) between the piston portion 33a of the needle valve 33 (the rear end of the needle valve 33) and the plunger member 36.
The needle valve 33 and the needle valve receiver 17J7t 30 are used to discharge the leaked fuel 11 leaking into the spring V29 LIs and the cylinder 28 through the minute gap into the fuel tank (not shown) outside the nozzle. Two combustion passages 37, 38 are provided, a first and a second combustion passage.
The two fuel discharge passages 37 and 38 are connected to the cylinder 28 at a predetermined distance pt in the axial direction of the cylinder 28 (in the direction of lift of the needle valve 33). The opening position of the first fuel discharge passage 37 to the cylinder 28 is such that the fuel injection hole 25 is narrowed by the throttle portion 33e of the one-dollar valve 33 to the above-mentioned throttle range of the lift range of the needle valve 33. The piston portion 33a of the needle valve 33 is in the range where the opening area is kept small.
On the other hand, the opening position of the second fuel discharge passage 28 to the cylinder 28 is set to a position beyond the maximum lift range of the needle valve 33, that is, the needle valve 33 is lifted to the full lift position. It is set at a position where it will not be blocked by the piston portion 33a even when the piston portion 33a is closed. Therefore, when the needle valve 33 is lifted, its piston portion 33a closes the first fuel discharge passage 37, and leaked fuel is trapped in the cylinder 28 between the piston portion 33a and the plunger member 36. The fuel pressure acting on the rear end surface of the plunge V member 36 is configured to suppress the lift leg of the needle valve 33 via the honeymoon leak fuel.

Furthermore, be careful of the portion of the second fuel discharge passage 38 that extends outside the nozzle body 27.
Three normally open 7t2 magnetic on-off valves are provided as switching valves for selectively switching the 38.

To explain the control system that controls the operation of this electromagnetic on-off valve 39, reference numeral 40 is an accelerator opening sensor for detecting the accelerator opening, and 41 is a rotational speed sensor for detecting the number of revolutions of the engine. , 42 are both the above-mentioned sensors 4
This is a control circuit that receives outputs of 0 and 41 and controls the operation of a valve drive circuit 43 for driving the electromagnetic on-off valve 39, and includes the accelerator distance sensor 4Q and rotation speed sensor 41.
The control circuit 42 and valve drive circuit 43 operate and control the electromagnetic on-off valve 39 (switching valve) according to the operating state of the engine, and when accelerating from low rotations or under low load, the three electromagnetic on-off valves are closed to prevent leakage. The fuel is discharged only through the first fuel discharge passage 37, and when accelerating from high revolutions or under medium 1 fJ load, the leaked fuel is discharged from the first and second fuel discharge passages by listening to the opening of the three valves. Mi1 discharge passage 3
The control device 44 is configured to perform the control in both 7.38 and 7.38.

Next, to explain the operation of the above embodiment, basically, when high pressure fuel is pumped from the fuel injection pump 11 to the fuel injection nozzle 10, the high pressure fuel is transferred to the fuel injection nozzle 10. 9 people enter the fuel pressure chamber 31 from the port 26 through the fuel passage 32, press the pressure receiving part 33c of the needle valve 33 through the fuel pressure chamber 31, and press the pressure receiving part 33c of the needle valve 33.
is lifted and paused against the biasing force of the nozzle spring 34, and by opening the needle valve 33, the fuel in the fuel pressure chamber 31 passes through the fuel nozzle hole 25 and is injected into the combustion air of the engine 1. Q=j is supplied.

Furthermore, the pressure of the high-pressure fuel introduced into the fuel inlet 26 of the fuel injection nozzle 10 also acts on the rear end surface of the plunger portion U 36 in the cylinder 28, pressing the plunger member 36 toward the needle valve 33, and pushing the plunger member 36 toward the needle valve 33. The lift operation of the needle valve 33 is controlled by applying fuel pressure to the part 36. The control for this needle valve 33 will be explained along the control flowchart shown in FIG. The rotational speed signals from the rotational speed sensor 41 are respectively input to the control device 44, and then, in step S3, it is determined whether or not acceleration is occurring based on the accelerator opening signal, and this determination is YES. When accelerating with
4, it is determined whether the engine is at low rotation speed or not based on the rotation speed signal, and if this determination is YES.
When it is, that is, acceleration from the low rotation range ■, Umako is J5 at step $5 and electric! 1lnl closing valve 39 is closed. As a result, the needle valve 33 of the fuel injection nozzle 10 can be opened at the screw 1-shaped portion 33 within its lift range.
Until the fuel a closes the first fuel discharge passage 37, the leaked fuel in the cylinder 28 that has flowed in from the spring honeycomb 29 is discharged through the first fuel discharge passage 37, while freely using the biasing force of the nozzle spring 34 as a resistance force. When it is lifted and the piston portion 33a closes the first fuel discharge passage 37,
Fuel is sealed in the cylinder 28 between the piston portion 37 and the plunger member S6, and the fuel pressure acting on the rear end of the plunger member S6 is transmitted to the needle valve 33 via the liquid-tight leak fuel. The lift is controlled to be suppressed by increasing the opening pressure of the needle valve 330. The opening of the first fuel discharge passage 37 to the cylinder 28 is opened when the needle valve 33 is in the throttle range in which the fuel nozzle 25 is throttled by the throttle portion 33e within its lift range. Since the needle valve 33 is arranged so as to be closed by the piston portion 33a, the lift of the needle valve 33 is suppressed by the needle valve 33.
is in the throttle range, the fuel injection rate 9A is kept small and the injection period is lengthened, as a result, afterburning is promoted and the pressure wave energy of the exhaust gas is increased. As a result, the pressure wave energy of pressure wave supercharging (pressure wave energy of the exhaust air to the intake air is transmitted effectively and quickly in the air 4), and the supercharging pressure increases immediately, thereby improving acceleration response. Incidentally, if the determination in step S4 is No, that is, when accelerating from a high rotation range, the three electromagnetic on-off valves are heard in step $6.As a result, the fuel 11r, the needle valve 3S of the I-nozzle 10 , the piston portion 33a is the first fuel discharge passage 37
Until the piston part 33a closes the first fuel ()1 outlet passage 37, the leaked fuel in the cylinder 28 is discharged from both the first and second fuel discharge passages 37,38.
Output the leaked fuel to the second fuel υI 1ffi k'fi 38
It is controlled so that it is discharged from the chisel to the riff 1 while being discharged from the chisel. Since the first part of the discharge passage 38 to the cylinder 28 is set at a position beyond the full lift range of the needle valve 33, the needle valve 33 is closed during its lift. It is now possible to lift freely without being inhibited by the plunger member 36, and the fuel injection OJ rate is kept high. As a result, the re-engine output has to be improved to ensure that the engine does not have any bumps; can be achieved.

On the other hand, when the determination in step S3 is No, that is, when it is not accelerating, it is determined in the next step S7 whether or not the load is low based on the accelerator opening signal, and this determination is YES. At a certain low load, step S
At 8, the solenoid opening valve 39 is closed, and as described above, by suppressing the lift of the needle valve 33 in the throttle range,
The state in which fuel is injected from the fuel nozzle holes 25 at high speed is maintained for a long period of time, promoting atomization of the injected fuel, increasing the combustibility of the fuel, and improving emission performance. on the other hand,
Step S above! At the time of medium to high load when the determination in 1 is No, three solenoid valves are opened in step S9 (above).
It is possible to improve the engine output corresponding to the load by ensuring sufficient fuel injection*qm.

Now, specifically, in a diesel engine with a pressure wave supercharger equipped with a 111 air surge tank with 8 suspensions and 1.5 alternating currents,
For the model equipped with a fuel injection pump with a plunger diameter of 10 mm and the model equipped with a fuel injection pump with a plunger diameter of 11 mm, the fuel injection amount is the same, and the supercharging pressure J5 and engine speed during acceleration are The rise characteristics were measured and the results are shown in FIGS. 4 and 5. According to the same figure,
Boost pressure and engine speed both increase faster in the engine with a blank diameter of 10 mm+ (solid line in the figure) than in the engine with a blank diameter of 11 mm (broken line in the figure), and the smaller the fuel injection rate, the faster the engine speed increases. It can be seen that the acceleration response is excellent.

In the above embodiment, the lift of the needle valve 33 is suppressed by the fuel pressure, thereby making the fuel injection rate variable. Various other types (i4 type), such as those equipped with injection nozzles to appropriately control them, can be adopted.

In addition, in the above embodiment, a diesel engine with pressure wave supercharging suppression was explained, but for example, if the exhaust turbo supercharging
It can be widely applied to other types of exhaust energy such as diesel engines equipped with a supercharging system, such as diesel engines equipped with a supercharging system that supercharges the intake air. It has the same effects and effects for a long time.

(Effects of the Invention) According to the above-described supercharging diesel engine of the present invention, the fuel consumption during acceleration is N'31 +! n emissivity decreases J: Sea urchin a, try to control it! This makes it possible to accelerate the increase in supercharging pressure at the beginning of acceleration and improve acceleration responsiveness.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention, FIG. 1 is an overall schematic explanatory diagram, FIG. 2 is a sectional view of main parts, FIG. 3 is a flowchart 1 of the control system, and FIG. 4. FIG. 45 and FIG. 5 are graphs showing experimental results showing the increase characteristics of supercharging pressure and engine speed during acceleration, respectively. 1...Engine, 4...Pressure wave supercharging) k, k0...
・Burn 1 injection nozzle, 35... injection rate control) several, 4
4...Control device. Figure 4 Figure 5 1'1M (sec) Figure 3

Claims (1)

[Claims] (1) In a supercharged diesel engine equipped with a supercharger that supercharges intake air using exhaust energy, an injection rate control mechanism that makes the fuel injection rate variable is provided, and the fuel injection rate is reduced during acceleration. A diesel engine with a supercharger, characterized in that a control device for controlling an injection rate control mechanism is provided in the engine.