JPH02176161A - Starting device of diesel engine - Google Patents

Abstract

PURPOSE:To make a starter motor lightweight and compact by throttling the intake air quantity by a throttle valve at the starting time of an engine, thereby reducing engine starting torque. CONSTITUTION:When the turning angle of a lever 12 (a second lever) exceeds the specified angle, a lever 10 (a first lever) is rotated by means of a change- point spring 11 as well as a throttle valve 3 is rotated integrally with the lever 10 so as to be closed or opened. In the first suction stroke in which a valve 3 is closed, air is supplied into a combustion chamber through the hole 5 of the valve 3, but the air quantity is small and throttled. In the second compression stroke, a decompression lever 6 is reset in the original position and an exhaust valve is closed, but large force is not needed to make a piston rise as the intake air quantity in the first suction stroke is small, and fuel injection is performed immediately before the second explosion stroke so as to perform ignition. In the suction stroke after the second one, the valve 3 is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a starting device for 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 a rope 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 effectively reduces the starting torque, the maximum 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 reduce the starting torque at the time of starting. 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. The present invention has been made by paying attention to this fact.

(Means for Solving the Problems) In order to solve the above problems, the diesel engine starting device of the present invention includes a throttle valve arranged in the intake passage of the diesel engine to limit the amount of intake air, and an axis of the throttle valve. a first lever fixed to the throttle valve, a second lever rotatably supported by the shaft of the throttle valve, and a predetermined position of the second lever by connecting the first lever and the second lever. a spring that rotates the first lever by rotating the first lever by more than an angle; and a spring that is fixed to the shaft of the decompression lever and rotates the second lever in the direction h in which the throttle valve closes when the decompression lever is operated. a third lever to move the
and a vacuum actuator that is operated by negative pressure in the intake passage to rotate the second lever in a direction in which the throttle valve opens, and when starting the engine, the intake air amount is throttled by the throttle valve to generate engine starting torque. The structure is designed to reduce the

(Operation) When the rotation angle of the second lever exceeds a predetermined angle, the first lever is rotated by the consideration point spring, and the throttle valve is rotated together with the first lever to close or open the valve. do. When the intake air volume is reduced during the first intake stroke using the throttle valve,
Since the amount of air in the combustion chamber is small, the force required to raise the piston during the second compression stroke is small. Moreover, even in this case, the maximum temperature during compression does not decrease compared to the case where the intake air amount is not throttled.

(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 diesel engine starting device according to an embodiment of the present invention, and Fig. 2 is a plan view of a diesel engine equipped with the same starting device.
A throttle valve 3 is disposed in the intake passage 1 so as to be openable and closable. The throttle valve 3 is fixed to a rotatable shaft 4.
A hole 5 of a predetermined area is formed in the valve to allow air to pass therethrough when the valve is closed. Reference numeral 6 denotes a decompression lever that is operated to open the exhaust valve to put the exhaust in a decombined state when starting the engine.A lever 8 as a third lever is fixed to the shaft 7 of this decombination lever 6. Reference numeral 8 denotes a flat plate portion 8a and a cylindrical column portion 8 protruding from the tip of the flat plate portion 8a in a direction perpendicular to the flat plate portion 8a.
b. One end of a lever 10 as a first lever is fixed to the foot 4 of the throttle valve 3, and one end of a balance spring 11 is fixed to the other end of the lever 10. The shaft 4 of the throttle valve 3 rotatably supports one end of an L-shaped lever 12 as a second lever, and the other end of the spring 11 is fixed to the middle part of the lever 12. has been done. The cylindrical portion 8b of the lever 8 is in contact with the tip of the lever 12 from the left side in FIG.
A cylindrical projection 13 is provided protruding from the tip of the lever 12. The protrusion 13 passes through a long hole 16 formed in the rod 15 of the vacuum actuator 14, and the diaphragm chamber 14a of the vacuum actuator 14 is connected to the throttle valve 3 of the intake passage 1 via the piping 17 and the valve device 21. It communicates with the downstream side. Vacuum actuator 1
Inside 4, there are a diaphragm 19 and a diaphragm 19.
A coil spring 20 is arranged to bias the diaphragm chamber 14a toward the opposite side of the diaphragm chamber 14a. Although not shown in the drawings, as is well known, by rotating the decompression prepper 6, the exhaust valve is pushed downward and opened. 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 decombinator 6 is rotated by the biasing force of the return spring. and return to the original position. The valve device 21 has a check valve 22 and a throttle passage 23 connected in parallel.

Next, the operation will be explained. Before the decombinator 6 is operated at the time of starting the engine, the levers 8, 10.degree. 12 are in the positions shown by the phantom lines in FIG. 1, and the throttle valve 3 is open as shown by the phantom lines. When the shaft 7 rotates due to the operation of the decompression prepper 6, the lever 12 is pushed to the right side by the cylindrical portion 8b of the lever 8 and rotates clockwise.
When the other end of the thinking point spring 11 moves to the right of the straight line connecting one end of the thinking point spring 11 and the axis of the shaft 4, the lever 10 is rotated counterclockwise by the biasing force of the thinking point spring 11, and the decombinator is rotated. When the operation of step 6 is completed, lever 8, 10.12
is in the position shown by the solid line.

Since the throttle valve 3 rotates together with the lever 10, when the operation of the decombination brakeper 6 is completed, the throttle valve 3 is fully opened as shown by the solid line. After the operation of the decombinator 6, the piston moves up and down by pulling the starting lobe, but since the first compression stroke is an exhaust decompression-like deafening, a large force is not required to raise the piston. Immediately before the first explosion stroke, the first fuel injection is performed, but at this time, the exhaust is in a decompressed state, so no ignition occurs. During the first exhaust stroke, the exhaust valve is opened to a greater extent than in the exhaust decompression state, and the decombinator 6
is rotated by the biasing force of the return spring and returns to its original position. Even if decompression prepper 6 returns, lever 8
Since the cylindrical portion 8b contacts the lever 12 from the left side, the lever 12 is not pushed to the left by the cylindrical portion 8b, and the throttle valve 3 continues to be fully open. 1st
In the second intake stroke, since the throttle valve 3 is closed, air is supplied to the combustion chamber through the hole 5 of the throttle valve 3. At this time, the flow passage cross-sectional area of the hole 5 is very small compared to the intake passage 2, so the amount of air supplied to the combustion chamber is smaller than when the throttle valve 3 is open, and the intake air amount is has been narrowed down. On the other hand, when the intake passage 1 becomes negative pressure, the check valve 2 of the piping 17 and the valve device 21
Since the diaphragm chamber 14a of the vacuum actuator 14, which communicates with the intake passage 1 via the valve 2, also has a negative pressure,
The vacuum actuator 14 operates to pull the rod 15 to the left, but since the valve device 21 has the throttle passage 23, the negative pressure in the diaphragm chamber 14a slowly decreases.

. As a result, the protrusion 13 of the lever 12 is pulled to the left by the rod 15, the lever 12 rotates counterclockwise, and the other end of the thought point spring 11 connects one end of the thought point spring 11 with the axis of the shaft 4. At point U, 9, which has moved to the left of the straight line, the lever 10 rotates clockwise due to the biasing force of the consideration point spring 11, and eventually the lever 10.12 returns to the position shown by the imaginary line. Therefore, the throttle valve 3, which rotates together with the lever 10, also returns to the fully open state as shown by the imaginary line. In the second compression stroke, the decombinator 6 has returned to its original position, and either the exhaust decompression state is released and the exhaust valve is closed, or the amount of intake air in the first intake stroke is small, so the piston No great force is required to raise the .

Then, just before the second explosion stroke, four fuel injections are performed and ignition occurs. In the second and subsequent intake strokes, since the throttle valve 3 is open, the intake air amount is not restricted, and the engine speed increases like a conventional engine and reaches a predetermined speed. That is, during the starting operation, the throttle valve 3 opens and closes at the timing shown in FIG. 3(a), and the lever 12 rotates at the timing shown in FIG. 3(b). The pressure on the downstream side changes as shown in FIG. 3(c), and the pressure in the diaphragm chamber 14a changes as shown in FIG. 3(d). Although FIG. 1 shows the configuration in a simplified manner for easy understanding, in reality, as shown in FIG. 2, the rod 15 of the vacuum actuator 14 and the lever 12 are connected to the lever 12a. The protrusion 1 is connected to the rod 15a through the rod 15a.
3 protrudes from the lever 12a.

Here, the intake throttling ratio (the ratio of the intake air passage cross-sectional area when the throttle valve 3 is fully opened and the intake air volume is not throttled to the intake air passage cross-sectional area when the intake air volume is throttled) and the engine The relationship between filling efficiency, maximum temperature during compression, and maximum pressure during compression is as shown in FIG. 4. In other words, if the amount of intake air is throttled so that the charging j'1 efficiency is about 70% in the first intake stroke, the maximum temperature during compression will be when the throttle valve 3 is fully open, as shown in Figure 4(b). It can be seen that the second fuel injection reliably ignites the fuel. Further, the maximum pressure during compression is about 30 kg/cd as shown in FIG. 4(c), which is about 1 kg/c smaller than when the throttle valve 3 is fully open. Therefore, if the intake air volume is not throttled in the first intake stroke as in the past,
As shown by the broken line in the figure, the lobe must be pulled with a very large force in the second compression stroke just before the end of the pulling of the starting lobe, whereas in the first compression stroke as in this example, If the amount of intake air is reduced so that the filling efficiency is about 70% during the intake stroke, the force that pulls the lobe can be effectively reduced, as shown by the solid line in FIG. Of course, the area of the hole 5 of the throttle valve 3 may be appropriately set within the allowable range to further reduce the amount of intake air and further reduce the force of pulling the lobe.

In this way, since the amount of intake air is reduced in the 1st fm intake stroke, the torque required to raise the piston in the second compression stroke can be effectively reduced. 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. Further, 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 reduced, and the engine can be made lighter, more compact, and lower in cost. In addition, the throttle valve 3 is automatically closed by the operation of the decombinator 6, and the throttle valve 3 is automatically opened by the negative pressure in the intake passage 1.
There is no need to separately open and close the throttle valve 3, and starting work can be performed easily and quickly. Further, since the throttle valve 3 can be mechanically closed by operating the decombinator 6, the valve closing operation is reliable, the manufacturing cost is low, and there are few failures. Furthermore, since the lever 10 is rotated by the biasing force of the point spring 11, the opening and closing operations of the throttle valve are quick and reliable. Note that a wire or the like may be used instead of the shaft as a means for interlocking the decombinator 6 and the lever 12.

(Effects of the Invention) As explained above, according to the present invention, the engine starting torque is reduced by throttling the intake air amount using the throttle valve when starting the engine. The force can be effectively reduced, and even those with weak strength can easily perform starting work. In addition, in the case of an electric start type diesel engine, the cranking force can be effectively reduced, so the capacity of the starter motor can be reduced.
Light weight, compactness, and cost reduction can be achieved. In addition, the throttle valve closes automatically when the decompression lever is operated, and the throttle valve opens automatically due to the negative pressure in the intake passage, so there is no need to separately open and close the throttle valve, eliminating the need for starting work. can be done easily and quickly. Furthermore, since the throttle valve can be mechanically closed by operating the decompression lever, the valve closing operation is reliable, the manufacturing cost is low, and there are few failures. Furthermore, since the first lever is rotated by the biasing force of the point spring, the opening and closing operations of the throttle valve are quick and reliable.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a diesel engine starting device according to an embodiment of the present invention, Fig. 2 is a plan view of a diesel engine equipped with the same starting device, and Fig. 3 is an explanation of pressure changes at various parts when starting the engine. Figure 4 is an explanatory diagram of the relationship between charging efficiency, maximum temperature during compression, and maximum pressure during compression against intake throttling ratio, and Figure 5 shows changes in the force required to pull the starting lobe when starting the engine. FIG. DESCRIPTION OF SYMBOLS 1...Intake passage, 3...Throttle valve, 4...Shaft, 6...Decompression lever, 7...Shaft, 8...Reno<
- (third lever), 10... lever (first lever)
-), 11... Thought point spring, 12... Lever (second
Reno <-), 14... Vacuum actuator patent applicant Yanmar Diesel Co., Ltd. Figure 1

Claims (1)

[Claims] 1. A throttle valve disposed in the intake passage of a diesel engine to limit the amount of intake air; a first lever fixed to the shaft of the throttle valve; and a first lever rotatably supported by the shaft of the throttle valve. a second lever, a spring that connects the first lever and the second lever and rotates the first lever by rotating the second lever by a predetermined angle or more; a third lever that is fixed and rotates the second lever in a direction in which the throttle valve closes by operation of a decompression lever; A starting device for a diesel engine, comprising: a vacuum actuator that rotates a valve in a direction in which the valve opens; and when starting the engine, the intake air amount is throttled by the throttle valve to reduce engine starting torque.