JPH03124963A - Starting method for diesel engine - Google Patents

Abstract

PURPOSE:To easily and quickly perform the starting work by squeezing the intake quantity when an engine is started, and releasing the squeeze after the engine rotating speed allowing the compression turnover is attained by only the inertial force of a rotary system including a flywheel in the unsqueezed state. CONSTITUTION:The intake quantity is squeezed by a throttle valve 27 to the preset pressure when an engine is started, then the intake quantity is gradually increased from the optical time. The torque required to lift a piston in the compression stroke at the time of the start is effectively reduced. The squeeze of the intake quantity is released after the lower-limit engine rotating speed allowing the compression turnover by only the inertial force of a rotary system including a flywheel in the unsqueezed state of the intake quantity is attained. The engine is easily and quickly started, and the stop or reverse rotation of the engine at the time of the start can be satisfactorily prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for starting a diesel engine.

(Prior Art) Conventional diesel engines generally do not have a valve in the intake passage, and the amount of intake air is not throttled.

Although it has been proposed to reduce the intake air volume to reduce noise during idling or to improve ignition performance during engine startup, it has not been possible to reduce the intake air volume to an extent that effectively reduces the starting torque when starting the engine. This has never been done before.

(Problem to be solved by the invention) Conventionally, the amount of intake air is not throttled at the time of starting, so the starting torque is large, and manual starting by pulling the lobe etc. by hand requires strong force, and electric starting using a starter motor requires a large amount of starting torque. Starting requires a large capacity starter motor.

That is, conventionally, it has been thought that if the intake air amount is reduced to an extent that can effectively reduce the starting torque, the temperature of the air in the combustion chamber during the compression stroke will decrease and ignition will not occur. Therefore, in the conventional proposal to throttle the intake air volume to improve ignition performance at startup, the engine's charging efficiency is reduced by several percent in order to increase the maximum temperature during compression by giving work to the intake air by restricting the intake air volume. The intake air amount is restricted to such an extent that the starting torque can be effectively reduced, and there is no idea of reducing the intake air amount to an extent that can effectively reduce the starting torque. In addition, in conventional proposals to reduce intake air volume to reduce noise during idling, the intake air volume is considerably reduced to ensure continuous idling operation, but this conventional method is only applicable during idling. However, it does not specifically reduce the starting torque.

However, according to experiments conducted by the inventors of the present invention, even if the intake air volume is throttled to the extent that the starting torque can be effectively reduced, the maximum temperature during compression does not drop compared to when the intake air volume is not throttled at all. found.

Focusing on this fact, the applicant of the present application has already made a proposal to throttle the intake air amount at the time of startup (for example, Japanese Patent Application No. 63-330895). When released, the engine may stop or run in reverse.

(Means for Solving the Problems) In order to solve the above problems, the diesel engine starting method of the present invention is a diesel engine starting method that reduces the engine starting torque by reducing the intake air amount at the time of engine starting. At some point, the intake air volume is throttled to a predetermined value, and then the intake air volume is gradually increased from an arbitrary point.
After the engine speed reaches the lower limit engine speed at which compression can be overcome only by the inertia of the rotating system including the flywheel without throttling the intake air amount, the intake air amount restriction is released.

(Function) When the amount of intake air is throttled during the intake stroke when starting the engine, the amount of air in the combustion chamber is small, so the force required to raise the piston during the compression stroke is small. In addition, the intake air volume continues to be throttled until the engine speed reaches the maximum engine speed at which compression can be overcome by nJ due to the inertia of the rotating system including the flywheel when the intake air volume is not throttled.
It is possible to effectively prevent the engine from stopping or rotating in reverse when starting.

(Example) Hereinafter, one example of the present invention will be described based on FIGS. 1 to 5.

FIG. 1 is a schematic configuration diagram of a starting device that employs a diesel engine starting method according to an embodiment of the present invention, and FIG. 2 is a side view of a diesel engine equipped with the same starting device.
1 is a cylinder head, and this cylinder head 1 is formed with an intake passage 2 as an intake path. An upstream end of the intake passage 2 is open to the atmosphere via an air cleaner 3, and an intake valve 4 is provided at the upstream end of the intake passage 2.
is located. A bonnet 5 is fixed on the cylinder head 1, and a valve arm chamber 6 is attached to the bonnet 5.
is formed. A cylinder head 1 is equipped with a fuel injection nozzle 9 facing a combustion chamber 8 of a cylinder head 7 and a glow plug 10. On the bonnet 5, an automatically releasing type (e.g. auto-return type) exhaust decompression lever (hereinafter referred to as "decompression lever") 11 is supported by the pivot 12 or I[, and around the holder 12 there is a return A spring (not shown) is installed. Decompression play area
11 is integrally provided with a semicircular protrusion 11a, and one end of the rod 14 is connected to the shaft 12 via a bottle, and the other end of the rod 14 is an example of a pneumatic pump device. It is connected to a diaphragm 16 of a diaphragm type pump device 15. The diaphragm chamber 17 of the diaphragm pump device 15 includes a diaphragm 16
A coil spring 18 is installed that biases the rod 14 toward the rod 14 side. The diaphragm chamber 17 of the diaphragm pump device 15 communicates with a diaphragm chamber 22 of a diaphragm actuator 21 as an example of a pneumatic actuator via a communication pipe 2o, and the diaphragm 23 of the diaphragm actuator 21 has one end of a rod 24. are connected. A diaphragm 23 is attached to the rod 2 in the diaphragm chamber 22 of the diaphragm actuator 21.
A coil spring 25 is installed to bias the fourth side. The other end of the rod 24 is pin-coupled to one end of a lever 26, and the other end of the lever 26 is connected to the outer periphery of a heel 28 of a throttle valve 27, which is an example of a valve rotatably installed in the intake passage 2. The mating is fixed. A hole 27a is formed in the throttle valve 27 to maintain an appropriate amount of intake air when the valve is closed. Two branch pipes are branched from the communication pipe 20, and the tips of the two branch pipes are opened to the atmosphere via an air filter 30. A valve device 31 is interposed in the two branch pipes, and the valve device 31 is composed of a reverse L valve 32 and a throttle flow path 33 that are connected in parallel to each other.

Reverse 11 - The valve 32 is connected to the air filter 30 from the communication pipe 20 side.
Allow air to pass only to the sides.

A limit switch 35 is disposed near the decombinator 11 as a switch means that is opened and closed by the protrusion 11a of the decombinator 11, and the limit switch 35 is attached to a bracket 36 fixed to the bonnet 5. The limit switch 35 is electrically connected to a controller 37 having a built-in timer relay, etc., and the controller 37 is electrically connected to the glow plug 10, a preheating buzzer 38, and three batteries.

The controller 37 controls the glow plug 10 and the preheating buzzer 38 based on the detection signal from the limit switch 35.
The drive current from three batteries is supplied to the The preheating buzzer 38 operates for a period of time from the start to the end of preheating the glow plug 10, based on the delay time set in the timer relay in the controller 37. In addition, throttle valve 2
7 constitutes, together with the diaphragm pump device 15, diaphragm actuator 21, etc. that drive the throttle valve 27, intake air amount limiting means 40 that throttles the intake air amount at the time of starting. Although not shown in the drawings, as is well known, the valve arm chamber 6 communicates with the inside of the crankcase, and as is well known, the decompression prepper 11 is shown in phantom lines from the solid line in FIG. By rotating the exhaust valve clockwise until it reaches this position, the exhaust valve is pushed down and opened. Furthermore, as is well known, in manual starting, the piston moves up and down by pulling the starting lobe, and during the exhaust stroke, the exhaust valve is further pushed down to the fully open state, and the decompression prepper 11 is activated by the return spring. It rotates counterclockwise due to the biasing force and returns to the position shown by the solid line.

Next, the operation will be explained. First, pull the starting lobe slightly to find the compression position. You can easily tell when the piston is in the compressed position because the resistance pulling on the lobe increases. When the compression position is found, at that point, the work of pulling the starting lobe is stopped, and the decombination breaker 11 is tilted to the right as shown by the imaginary line in FIG. 1 to set the exhaust decompression state. As a result, the protrusion 11a of the decompression prepper 11 presses the detection rod of the limit switch 35, so the limit switch 35 is closed and the detection signal 1a is supplied to the controller 37. As a result, the controller 37 controls the glow plug 1
At the same time, a driving current is supplied to a preheating buzzer 38 for a time corresponding to the preheating time of the glow plug 10 to make it emit a sound.

On the other hand, when the decompression prepper 11 is set, the exhaust valve opens and enters the exhaust decompression state, and the rod 14 is pushed to the right, causing the diaphragm 16 of the diaphragm pump device 15 to deform against the biasing force of the coil spring 18. death,
The air in the diaphragm chamber 17 is forced out into the communication pipe 20, which opens the check valve 32 of the valve device 31.
Air passes through check valve 32 and is released to the atmosphere. Therefore, the pressure in the diaphragm chamber 22 of the diaphragm actuator 21 does not increase, and the throttle valve 27 remains fully open. And when the glow plug 10's p heat is completed,
The preheating buzzer 38 starts to sound or stops, so at this point, pull the starting lobe in earnest. As a result, the piston moves up and down, and as soon as it enters the first exhaust stroke, the exhaust valve is opened more widely than in the exhaust decompression state, and the decombinator 11 is rotated counterclockwise by the biasing force of the return spring. Return to the caustic state shown in Figure 1. This opens the limit switch 35, but the controller 37 continues to energize the glow plug 10 for a predetermined period of time. On the other hand, the rod 14 is pulled to the left by the return of the decompression prepper 11, and the diaphragm 16 of the diaphragm pump device 15 is deformed. type actuator 2
Both the diaphragm chambers 22 and 1 become negative pressure. At this time, since the reverse 11-4 valve 32 is closed by negative pressure, the atmosphere does not enter through the reverse 1-4 valve 32. When the diaphragm chamber 22 of the diaphragm type actuator 2 becomes negative pressure, the diaphragm 23 or the coil spring 18 is forced into a closed shape, and the rod 24 is pulled upward, causing the lever 2 to move upward.
6 rotates counterclockwise, and the throttle valve 27 is fully closed as shown by the imaginary line in FIG. After this, the pressure in the diaphragm chamber 22 of the diaphragm actuator 21 is reduced to
The air pressure gradually approaches atmospheric pressure due to the air flowing in little by little from the throttle channel 33 of No. 1. When the negative pressure in the diaphragm chamber 22 of the diaphragm actuator 21 rises to a pressure that is balanced with the set load set by the coil spring 25, the throttle valve 27 begins to open and finally opens fully.

That is, by setting the flow passage cross-sectional area of the throttle passage 33 of the valve device 31 to an appropriate size, the time point at which the throttle valve 27 begins to open can be adjusted to an appropriate time after the completion of the first intake stroke. In addition, the point at which the throttle valve 27 is fully opened can be adjusted at an appropriate time thereafter.

The timing of the above operation is shown in FIG. Figure 3(a)
shows the operation timing of the decompression prepper 11, (b) shows the operation timing of the preheating buzzer 38, (c) shows the timing of energizing the glow plug 10, (d) shows the piston position, and (e) shows the timing of the energization of the glow plug 10. Diaphragm actuator 2
The pressure in the diaphragm chamber 22 of FIG. 1 and the opening degree of the throttle valve 27 are shown in FIG. In addition, Figure 3 (
Pl in e) is the pressure in the diaphragm chamber 22 of the diaphragm actuator 21 at the time when the pressure rises to a level that is in equilibrium with the set load set by the coil spring 25, and from this point on, the throttle valve 27 starts to open.

By the way, the first fuel injection is performed just before the first explosion stroke, or at this time, the exhaust is in a decompressed state, so even if it is green, it will not do any effective work. Furthermore, when the intake valve 4 opens during the first intake stroke and the piston descends, air is supplied to the combustion chamber 8 through the hole 27a of the throttle valve 27. At this time, since the flow passage cross-sectional area of the hole 27a of the throttle valve 27 is very small compared to that of the intake passage 2, the amount of air supplied to the combustion chamber 8 is smaller than that when the throttle valve 27 is open. This means that the amount of intake air is reduced. In this example, below the self-ignition limit (for example, compression pressure 15
kg/eJ). In the second compression stroke, the decompression prepper 11 returns, the exhaust decompression state is released and the exhaust valve is closed, but since the amount of intake air in the first intake stroke is small, the piston moves upward. let No great force is required.

In particular, in this embodiment, the amount of intake air is limited to below the self-ignition limit, so that the starting rope can be pulled with a small force since the amount of intake air is very small.

Then, fuel injection is performed just before the second explosion stroke,
ignite. At this time, the amount of intake air is limited to below the self-ignition limit, or the glow plug 10 causes forced ignition, so that ignition is successful. Thereafter, the forced ignition by the glow plug 10 is repeated until the throttle valve 27 starts to open. When the throttle valve 27 is fully opened, the intake air amount is not throttled during the intake stroke, and the engine speed increases like a conventional engine and reaches a predetermined speed.

Here, if the intake air amount is not throttled with the throttle valve 27 left open at the time of starting, the force F for pulling the starting rope (hereinafter referred to as "rope pulling force") is as shown in Fig. 4 (a). Therefore, the engine rotation speed n becomes as shown in FIG. 4(b). Further, when the throttle valve 27 is closed to restrict the intake air amount at the time of starting, the rope pulling force F becomes as shown in FIG. 5(a), and the engine speed n becomes as shown in FIG. 5(b). In other words, if the intake air amount is not throttled, the difference in engine speed due to explosion will be ΔnI+, Δ since the intake air amount is large.
n12. ... is large, and the rate of increase in engine speed n is large. However, the inertial force G of the rotating system including the flywheel
Lower limit engine speed N that can overcome compression based on D2
O is large, so the top Fi of the rope pulling force F
l, FI2 is large. On the other hand, if the intake air volume is throttled during startup, the inertia force GD of the rotating system including the flywheel
The lower limit engine speed N1 that can overcome compression with only 2
is smaller than NO, so the peak of the rope pulling force F is F21. F22 becomes smaller than Fil and F12.

However, since the amount of intake air is small, the difference in engine speed resulting from the explosion Δn21. ．． Δn22. Δn23.・
...is small. In other words, the rate of increase in engine speed n at the time of engine startup is small. Under such circumstances, if the throttle valve 27 is suddenly opened below a certain speed that is smaller than NO, the engine speed will increase. N
Even if it exceeds 1, only compression override is possible, and the engine may stop, start, or reverse. Therefore, by appropriately setting the flow passage cross-sectional area of the throttle flow passage 33 (FIG. 1) of the valve device 31, the throttle valve 27 is prevented from fully opening until the engine speed exceeds NO.

Note that in FIGS. 4 and 5, the horizontal axis is time, and the arrow T indicates the timing of the compression top.

In this way, since the intake air amount is throttled by the throttle valve 27 when starting the engine, the torque required to raise the piston during the compression stroke can be effectively reduced. Moreover, valve device 3
1 adjusts the opening timing of the throttle valve 27 and continues to throttle the intake air until the engine speed reaches NO, which effectively prevents the engine from stopping or reversing during startup.
゛, I can.

Further, as in this embodiment, if the glow plug 10 is provided to force ignition, the amount of intake air can be reduced to below the self-ignition limit. Therefore, in the case of a manually started diesel engine, the force required for starting can be effectively reduced, and even a person with weak strength can easily start the engine. Furthermore, in the case of an electrically started diesel engine, since the cranking force can be effectively reduced, the 8ffL of the starter motor can be reduced, and the engine can be made lighter, more compact, and lower in cost. Further, even if the intake air amount is not reduced to below the self-ignition limit, the glow plug 10 ensures ignition, and failure to start can be effectively prevented.

Furthermore, as in this embodiment, if the limit switch 35 for energizing the glow plug 10 is activated by operating the decombinator 11, no special operation is required for energizing the glow plug 10, and the engine Start-up work can be done easily and quickly. In addition, as in this embodiment, if the automatic return type decompression prepper 11 is used and the throttle valve 27 is closed by the return of the decompression prepper 11, there is no need to separately close the throttle valve 27, and the start-up Work can be done easily and quickly. Furthermore, as in this embodiment, if the pneumatic circuit for driving the throttle valve 27 is configured to communicate with the atmosphere only through the valve device 31, and the other parts are completely sealed, There is no risk of lubricating surfaces etc. entering the pneumatic circuit in the form of mist, and therefore, even if used for a long period of time, there will be no accidents such as the throttling flow path 33 of the valve device 31 being blocked by a pool or the like. Excellent reliability and durability. In addition, the configuration of this embodiment has almost no mechanical parts such as link mechanisms, so there is no malfunction or failure due to wear etc. Therefore, it is excellent in reliability and durability, and at the same time as mentioned above. Despite these excellent advantages, the overall H'4 construction is relatively simple and can be manufactured at low cost.

(Another Example) In the above example, the diaphragm pump device 15 is driven and the limit switch 35 is activated by operating the decombinator 11, but the present invention is limited to such a configuration. For example, by operating the recoil lobe, the diaphragm pump device 1
Eleven units may be configured to drive the limit switch 35 and operate the limit switch 35.

Further, in the above embodiment, the throttle valve 27 is driven by the diaphragm actuator 21, but the present invention is not limited to this configuration; for example, the throttle valve 27 is driven using a solenoid. 2
7 may be configured to be driven.

(Effects of the Invention) As explained above, according to the present invention, since the amount of intake air is throttled when starting the engine, the torque required to raise the piston during the compression stroke can be effectively reduced. Therefore, in the case of a manually started diesel engine, the force required for starting can be reduced effectively, and even a person with weak strength can easily and quickly start the engine.

Furthermore, in the case of an electrically started diesel engine, since the cranking force can be effectively reduced, the capacity of the starter motor can be minimized, making it possible to reduce weight, size, and cost. In addition, after the engine speed reaches the lower limit of engine speed at which compression can be overcome only by the inertia of the rotating system including the flywheel without restricting the intake air amount, the intake air amount restriction is completely released. This effectively prevents the engine from stalling or reversing when starting.

In addition, by installing a glow plug and forcing ignition,
The amount of intake air can be reduced to below the self-ignition limit. Therefore, in the case of a manually started diesel engine, the force required for starting can be further reduced, and even a person with weak strength can start the engine more easily and quickly. In addition, in the case of an electric start type diesel engine, the cranking force can be further reduced, so the capacity of the starter motor can be further reduced.
Lighter, more compact, and lower costs can be achieved even better. Furthermore, even if the intake air volume is not reduced to below the self-ignition limit, the glow plug ensures a spark, effectively preventing starting failures.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a starting device that employs a diesel engine starting method according to an embodiment of the present invention, Fig. 2 is a side view of an easel engine equipped with the starting device, and Fig. 3 is an engine starting method. Fig. 4 is an explanatory diagram of the rope pulling force and engine rotation speed when starting the engine when the intake air amount is not throttled;
FIG. 5 is an explanatory diagram of the rope pulling force and engine rotational speed at the time of engine starting when the intake air amount is throttled.

Claims (1)

[Scope of Claims] 1. A method for starting a diesel engine that reduces the engine starting torque by reducing the amount of intake air when starting the engine,
The intake air amount is throttled to a predetermined value at the beginning of engine startup, and then the intake air amount is gradually increased from an arbitrary point in time, so that the engine speed can be overcome by compression only by the inertia of the rotating system including the flywheel without throttling the intake air amount. A method for starting a diesel engine, characterized in that the restriction of the intake air amount is released after the engine speed reaches the lowest possible engine speed. 2. The method for starting a diesel engine according to claim 1, characterized in that the ignition is forcibly ignited by a glow plug when starting the engine.