JPS5836191B2 - Vacuum advance angle control device for gasoline engine with air governor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum advance angle control device for a gasoline engine with an air governor, which is mainly used in industrial vehicles.

When using a general gasoline engine in an industrial vehicle that frequently performs work under conditions such as high rotation, high load, or high rotation and low load, an air governor is installed between the carburetor and the intake manifold to maximize engine performance. The output rotation speed is controlled by the opening degree Q of the governor throttle valve in the air governor, and the advance angle control for automatically adjusting the engine ignition timing is
A vacuum advance device similar to that of a general gasoline engine is used, and the vacuum advance angle control is performed by changing the negative pressure based on a vent hole 0 for controlling the vacuum advance angle, which is provided near the throttle valve of the carburetor.

On the other hand, the engine speed during normal operation varies depending on the opening of the carburetor's throttle valve and the level of load acting on the engine. Therefore, engine ignition timing control depends not only on the opening of the throttle valve but also on the engine. It is necessary to do this so that it can respond to the rotation speed that changes depending on load fluctuations.

However, with conventional devices that use the carburetor's vent as a negative pressure detection port for air advance control, it is difficult to ignite properly in response to engine speed changes related to engine load fluctuations under conditions where the throttle valve opening is constant. Timing control is not achieved.

In other words, when the throttle valve opening is held constant (for example, fully open), the engine load is high (
Low load (during unloading work, climbing slopes, etc.) to low load (driving on flat land, etc.)
When the engine speed fluctuates, the engine speed increases more rapidly than under high load. The engine is controlled to almost the same state as when the load is high, and as a result, a phenomenon occurs in which the ignition timing is delayed from the appropriate timing corresponding to the engine rotational speed Q at that time.

This is because, as mentioned above, the negative pressure for vacuum advance control is obtained from the vicinity of the throttle valve in the carburetor.

That is, when the engine rotates at high speed and the load is low, the engine speed increases R-f. At K, the fuel inflow speed increases, and as a result, the negative pressure in the fuel mixture intake passage increases, causing the governor throttle valve to move to a smaller opening than when under high load. The negative pressure in the passage leading from the governor throttle valve to the intake manifold increases, but the negative pressure in the passage leading to the carburetor brake throttle valve and the governor throttle valve remains constant under high load as long as the throttle valve opening is kept constant. The condition is almost the same as that (this is maintained), and the vacuum advance control vent detects the negative pressure on the carburetor brake side, where there is no change in negative pressure despite the difference in negative pressure between the two passages. This is due to the inability to detect the correct negative pressure required for advance angle control.

However, when the engine is running at high speed and under low load, the ignition timing may be delayed (the resulting temperature of the exhaust gas may rise excessively, causing problems such as burnout or overheating in various parts of the engine). However, there were other problems such as increased fuel consumption, reduced output, and increased impurities in the exhaust gas.

The present invention was made for the purpose of eliminating the above-mentioned conventional drawbacks, and, in a gasoline engine equipped with an air governor, when the governor throttle valve of the air governor is in the closed position, the governor throttle valve is In the fuel mixture suction passage leading to the cylinder suction hole, a vent hole for vacuum advance control, which is separate from the vent hole opened in the carburetor, is drilled to allow speed control by the air governor. In order to appropriately control the ignition timing in response to changes in engine speed due to changes in the load acting on the engine over a range of It is also intended to solve the problem at low loads, prevent excessive temperature rises in the exhaust gas, and purify the exhaust gas.

Hereinafter, illustrated embodiments embodying the apparatus of the present invention will be described in detail.

As shown in the figure, an air governor 1 is installed between a carburetor brake 2 and an intake manifold 3, and as is commonly known, a throttle valve 4 of the carburetor 2 is opened and closed by pressing an accelerator pedal (not shown). Governor throttle valve 5 of air governor 1
is controlled to open and close by fluctuations in the negative pressure within a negative pressure chamber 8 that communicates with the fuel mixture intake passage 6 through a small hole 7.

That is, one end of the rod 9 is connected to the pin 1 at the upper end of the governor throttle valve 5 that controls the maximum output rotation speed of the engine.
0, and the other end f of this rod 9 is connected to a piston 11 that is slidable within the negative pressure chamber 8, so that the governor throttle valve 5 and the piston 11 are connected so as to interlock with each other. Although not shown, the governor throttle valve 5 is always urged in the open direction by a spring.

Note that one end of the negative pressure chamber 8 is connected to air so that the negative pressure inside the negative pressure chamber 8 acts on one side of the piston 11, and the atmospheric pressure acts on the other side. ing.

Therefore, the governor throttle valve 5 closes against the spring when the negative pressure in the negative pressure chamber 8 is high, and opens by the urging force of the spring when it is low.

Vacuum advance device 12 for adjusting the ignition timing of the engine
The diaphragm 14 disposed in the airtight chamber 13 in FIG.
7, and the diaphragm 14 is pressed by a spring 18 housed in the airtight chamber 13.

Thus, the airtight chamber 13 is communicated with a vent hole 20a for controlling the vacuum advance angle provided in the carburetor 2 and a vent hole 20b for controlling the vacuum advance angle provided in the air governor 1I through a communication pipe 19, respectively. Due to the balance between the suction force caused by the negative pressure C in the airtight chamber 13 and the pressing force by the spring 18, the play force plate 17 is rotated via the diaphragm 14 and the rod 15 to adjust the ignition timing in the engine. ing.

The vent hole 20b provided in the air governor 1 is opened at a portion of the wall surface of the air governor that faces the uppermost portion of the peripheral edge of the governor throttle valve 5 when the governor throttle valve 5 is in the closed position. The vent hole 20b is set to be in a closed state when the throttle valve 5 is in a closed position (during idling).

That is, the control of the diaphragm 14 in the airtight chamber 13 in the vacuum advance angle device 12 is performed by the negative pressure released from the vent hole 20a opened upstream of the throttle valve 4 in the carburetor 2 during idling.

There is a ridge 21 between the ventilation hole 20a and the communication pipe 19,
At medium and high speeds (this is the vent hole 2 on the governor throttle valve 5 side)
The diaphragm 14 is configured to be controlled by the negative pressure drawn from the diaphragm 0b.

This embodiment is constructed as described above, and its operation will be explained below.

When the engine is in a stopped state, a passage portion P1 of the fuel mixture intake passage 6 from the lower surface of the governor throttle valve 5 to the intake manifold 3 and a passage portion P2 between the upper surface of the valve 5 and the lower surface of the throttle valve 4 of the carburetor 2.
Since there is no pressure difference between the negative pressure chamber 8 and the atmospheric pressure f, the governor throttle valve 5 is held in a fully closed state by the tension of a spring (not shown) as shown by the solid line in FIG. There is.

Next, a description will be given of low speed rotation such as when the engine is idling.

In this case, the throttle valve 4 of the cab brake 2 is in the closed position (as shown in FIG. The negative pressure inside the pressure chamber 8 also increases,
The governor throttle valve 5 is displaced to a closed position against a spring (not shown) as shown by a phantom line,
The uppermost part of the circumferential end of the valve 5 closes a vent hole 20b for vacuum advance control provided in the air governor 1.

Therefore, the vacuum advance angle control at this time is performed by the vent hole 20a opened in the carburetor brake 2.

In this case, the vent hole 20a communicates with the atmosphere, so the advance angle remains at O, and the ignition timing is controlled to the appropriate ignition timing corresponding to the low speed rotation of the engine.

When the engine rotates at high speed (this will be explained with reference to FIG. 1).

In this case, when the accelerator pedal is depressed, the throttle valve 4 of the carburetor 2 becomes almost fully open, the flow rate of the fuel mixture increases, and the P2 of the fuel mixture intake passage 6 increases.
Since the negative pressure in that part decreases, the negative pressure in the negative pressure chamber 8 in the air governor 1 also decreases, the governor throttle valve 5 is gradually opened by a spring (not shown), and the engine speed increases accordingly.

In such a state, the downstream side of the governor strophtle valve 5 in the air governor 1, that is, P1 of the suction passage 6
The negative pressure of the P2 section is higher than that of the P2 section, and the carburetor 2
Since there is a vent hole 20a on the side (there is a pattern 21), the vacuum advance device 12 is properly controlled by the negative pressure generated through the air governor 1 (vent hole 20b).

That is, when a high load is acting on the engine during high-speed rotation, such as during unloading work, the governor throttle valve 5 is controlled to the open position as shown by the solid line in Figure 1, so the vacuum advance angle is The control device 12 has a ventilation hole 20a.
Because of the presence of the markings 21, the low negative pressure on the side of the carburetor 2 is not drawn from the vent hole 20a, but is transferred to the downstream side of the governor throttle valve 5, that is, the suction passage 6, through the vent hole 20b.
The above negative pressure acts on the airtight chamber 13 of the vacuum advance device 12, and the diaphragm 14 balances the suction force due to the negative pressure with the compression force of the spring 18. C, the force plate 17 of the continuator 16 is rotated via the rotor 15, and the ignition timing is adjusted to the rotational speed C when a high load is applied to the engine.
Adjust to accommodate this.

In addition, when the engine rotates at high speed and the load acting on the engine is low, the engine speed will be higher than when the engine is under high load as long as the throttle valve opening of the brake brake is kept constant. As a result, the inflow speed of the fuel mixture becomes faster and the negative pressure in the P1 and P2 portions of the fuel mixture intake passage 6 becomes higher. Pressure chamber 8
The negative pressure inside becomes high.

Therefore, as shown by the imaginary line in FIG. 1, the governor throttle valve 5 rotates in the closing direction and its opening becomes smaller than when the load is high.

That is, when the load is low, the engine speed increases and the opening degree of the governor throttle valve 5 decreases, so that the negative pressure in the downstream side of the governor throttle valve 5 in the fuel mixture flow passage 6, that is, the P1 portion becomes high. The difference in negative pressure between the P1 portion and the P2 portion becomes even larger than when the load is applied.

Since the thus increased negative pressure acts on the airtight chamber 13 of the vacuum advance device 12 through the vent hole 20b,
The diaphragm 14 is further displaced toward the airtight chamber 13 than when the load is high, and the play force plate 17 of the interrupter 16 is rotated in the advancing force direction.

As a result, the ignition timing is adjusted to an appropriate timing corresponding to the engine speed.

That is, according to the device of this embodiment, the vacuum advance angle is adjusted according to the opening degree of the governor throttle valve 5 in the air governor 1 so as to correspond to the engine speed when the load used on the engine is high or low. It can be controlled to obtain appropriate ignition timing.

As described in detail above, the present invention incorporates an air governor between a carburetor brake and an intake manifold, and the carburetor brake is provided with a vacuum advance so as to open upstream of the throttle valve when the throttle valve is in the closed position. In a gasoline engine provided with a vent hole for angle control, the air governor includes the peripheral edge of the governor sloftle valve when the governor slottle valve is in the closed position (thus, the periphery of the governor slottle valve in the closed position, and A vent hole for vacuum advance control, separate from the vent hole of the cab brake, is provided on the downstream side of the open position (when it is in the open position), and a ridge is provided on the vent hole of the cab brake. As a result, it was possible to obtain a vacuum advance angle that corresponds to the opening degree of the governor throttle valve, and as a result, the ignition timing could be adjusted appropriately in response to fluctuations in engine speed due to changes in the load acting on the engine. can be controlled.

Therefore, according to the present invention, the drawbacks that occur when the engine rotates at high speed and under low load can be eliminated, resulting in the following effects.

1. It can suppress excessive temperature rises in exhaust gas, extend the life of exhaust pipes and mufflers, prevent overheating, and improve the durability of various parts of the engine.

2. Fuel efficiency can be improved.

3. Impurities in exhaust gas can be reduced.

4. A decrease in output can be prevented.

Furthermore, since the device of the present invention is designed to have a vent hole for controlling the vacuum advance angle on the air governor side, it has an effect that can be easily implemented in a ready-made device and is hard to overlook.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view showing vacuum advance angle control when the engine is rotating at high speed, and FIG. 2 is a sectional view showing vacuum advance angle control when the engine is rotating at low speed. 1... Air governor, 2... Cab brake, 3...
Intake manifold, 4...throttle valve,
5... Governor throttle valve, 6... Fuel mixture suction passage, 12... Vacuum advance angle device, 16... Intermittent, 20a, 20b... Ventilation hole for vacuum advance angle control.

Claims (1)

[Claims] 1. An air governor is installed between the carburetor brake and the intake manifold, and the air governor is installed in the carburetor brake so that it opens upstream of the throttle valve when the throttle valve is in the closed position (Q). In the gasoline engine, the air governor has a position that is closed by the peripheral edge of the governor throttle valve when the governor throttle valve is in the closed position, and a position that is closed by the peripheral edge of the governor throttle valve when the governor throttle valve is in the open position. A vacuum advance angle control device, characterized in that a vent hole for controlling the vacuum advance angle separate from the vent hole of the cab brake is provided at a downstream position, and a throttle is provided in the vent hole of the cab brake.