JPS595789B2 - 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 where work is frequently performed under conditions such as high-speed, high-load and high-speed, low-load conditions, an air governor can be installed between the carburetor and the intake manifold to increase the engine's maximum output speed. is controlled by the opening of the governor throttle valve in the air governor, and the advance angle control for automatically adjusting the engine's ignition timing uses a vacuum advance angle device similar to that used in general gasoline engines.

This is done by changing the vacuum advance control through a vent hole located 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 the 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 speed. It is necessary to do this in a way that can accommodate the rotational speed that changes according to load fluctuations.

However, with conventional devices that use the carburetor's vent as a negative pressure detection port for advance angle 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 engine load changes from high load to low load while the throttle valve opening is held constant (for example, fully open), the engine speed will increase even more than when the load was high, so Although it is necessary to advance the ignition timing as the engine speed increases, the advance angle is controlled to be almost the same as under high load, and as a result, the ignition timing is adjusted to the engine speed at that time. There is a phenomenon in which the appropriate time to respond is delayed.

This is because, as mentioned above, the negative pressure for vacuum advance control is drawn from near the throttle valve in the carburetor neck.

In other words, when the engine is running at high speed and under low load, the fuel inflow speed increases as the engine speed increases, and as a result, the governor throttle valve increases as the negative pressure in the fuel mixture intake passage increases. Since the opening is displaced to be smaller than when loaded, the negative pressure in the passage from the governor throttle valve to the intake manifold becomes high, but the negative pressure in the passage from the carburetor throttle valve to the Karakahana throttle valve increases As long as the valve opening is kept constant, the condition will remain almost the same as under high load, and even though there is a difference in negative pressure between the two roads, the vent hole for vacuum advance control will maintain the negative pressure. This is due to the fact that it is not possible to detect the negative pressure on the carburetor side, which is not causing any change, and to detect the correct negative pressure required for advance angle control.

However, when the engine is rotating at high speed and under low load, the temperature of the exhaust gas may rise excessively due to the delay in ignition timing, which may cause problems such as burnout or overheating in various parts of the engine. In addition, 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 with an air governor, vent holes are provided on the carburetor side and on the air governor or intake manifold side, respectively, leading to the airtight chamber of the vacuum advance device. At the same time, a switching pulp is installed in the passage connecting these two ventilation holes and the airtight chamber to selectively switch the position where the negative pressure to be applied to the airtight chamber is drawn, and the air governor acts within the speed control range. The present invention provides an improved vacuum advance control device that can properly control the ignition timing in response to changes in engine speed due to changes in load, thereby solving problems particularly when the engine is running at high speed and under low load. This is an attempt to solve the problem, prevent an excessive temperature rise 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, the air gun 1 is installed between a carburetor 2 and an intake manifold 3, and as is generally known, the throttle valve 4 of the carburetor 2 is activated when an accelerator pedal (not shown -) is depressed. The governor throttle valve 5 of the air governor 1 is opened and closed.
Opening and closing is controlled by fluctuations in the negative pressure in 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 of this rod 9 is connected to a piston 11 that is slidable within the negative crown 8, so that the governor throttle valve 5 and the piston 11 are connected so as to interlock with each other. and governor throttle valve 5
Although not shown, it is always biased in the open direction by a spring.

Note that one end of the negative pressure chamber 8 is communicated with the atmosphere, so that the negative pressure in the negative pressure chamber 8 acts on one side of the piston 11, and the atmospheric pressure acts on the other side.

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 engine ignition timing
A diaphragm 14 disposed in an airtight chamber 13 is connected to a breaker plate 17 of a interrupter 16 by a rod 15.
The diaphragm 14 is pressed by a spring 18 housed in the airtight chamber 13.

Therefore, in the vacuum advance angle device 12, the airtight chamber 13 is
Appropriate positions of the wall of the carburetor 2 located upstream of the throttle valve 4, that is, above the top of the peripheral edge of the throttle valve 4 when the throttle valve 4 is in the closed position, and the wall of the intake manifold 3 Vacuum advance angle control ventilation holes 20a,
20b via the communication pipe 19 and the switching pulp 22, and the balance between the suction force due to the negative pressure acting in the airtight chamber 13 and the pressing force due to the spring 18 causes the air to flow through the diaphragm 14 and the rod 15. The breaker plate 17 is rotated to adjust the ignition timing of the engine.

When the switching valve 22 is formed within the wall of the air governor 1, it can be switched in conjunction with the opening/closing operation of the governor throttle valve 5, that is, in response to the high or low engine speed.

That is, the switching valve 22 has three boats 24a to 24.
The boat 24a at one end communicates with the vent 20a of the carburetor 2, the boat 24b at the other end communicates with the vent 20b of the intake manifold 3, and the boat 24c in the middle communicates with the vacuum advance angle. It communicates with a communication pipe 19 that communicates with the airtight chamber 13 of the device 12, and is configured such that the ventilation hole 20as20b for the airtight chamber 13 is switched by lateral sliding displacement of the spool valve 27. The valve rod 28 of No. 27 is connected to the governor throttle valve 5 by a pin 10 similarly to the rod 9 for the negative pressure chamber 8 described above.

In this embodiment, the switching valve 22 has a rotational speed of, for example, 1500 without load when the engine is in operation.
When the rpm is below, the airtight chamber 13 is communicated with the vent hole 20a on the carburetor side, and when it is above the rpm, the airtight chamber 13 is communicated with the vent hole 20b on the governor side. In the description, when the engine rotation speed is 150° rpm or less, it is defined as low-speed rotation, and when it is higher than that, it is defined as high-speed rotation.

This embodiment is configured as described above.

The effect will be explained below.

Note that 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 between the upper surface of the pulp 5 and the lower surface of the throttle valve 4 of the carburetor 2. Since there is no pressure difference with the portion P2 and the inside of the negative pressure chamber 8 is at approximately atmospheric pressure, the governor throttle valve 5 is held in a fully open state by the tension of a spring (not shown) as shown by a solid line in the drawing.

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

In this case, since the throttle valve 4 of the carburetor 2 is in the closed position as shown by the imaginary line in the drawing, the negative pressure in the 21 and 22 parts of the fuel mixture intake passage 6 becomes high, and the negative pressure in the air governor 1 increases. The negative pressure in the chamber 8 also increases, and the governor throttle valve 5 is displaced to the closed position against a spring (not shown) as shown in phantom in the drawing.

Therefore, the spool valve 27 of the switching knob 22 connected to the governor throttle valve 5 via the valve rod 28 moves to the left in the figure, and the vent hole 20a of the carburetor 2 communicates with the airtight chamber 13.

Therefore, the vacuum advance angle control at this time is the carburetor 2FC.
This is done by the vent hole 20a that has been opened, and since the vent hole 20a in this case draws almost atmospheric pressure, the advance angle remains at 0 and is set at an appropriate level corresponding to the low speed rotation of the engine. Controlled by ignition timing.

To explain when the engine rotates at high speed, in this case, when the accelerator pedal is depressed, the throttle valve 4 of the carburetor 2 becomes almost fully open as shown by the solid line in the drawing, the flow rate of the fuel mixture increases, and the negative As the pressure decreases, the negative pressure in the negative pressure chamber 8 of 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.

When the governor throttle valve 5 is opened to a state where the engine speed can be increased to the above-mentioned set speed 150 rpm or more, the spool valve 27 of the switching valve 22 moves to the right in the figure, and the air vent 20b of the intake manifold 3 is opened. communicates with the airtight chamber 13, the vacuum advance angle device 1
The control in step 2 is properly performed by the negative pressure released through the vent hole 20b provided in the intake manifold 3.

That is, when a high load is acting on the engine during high-speed rotation, such as during unloading work, the air hole 20b for vacuum advance control is used to control the fuel mixture between the lower surface of the governor throttle valve 5 and the intake manifold. Since the negative pressure in the 21 part of the air intake passage 6 is drawn,
The above-mentioned negative pressure acts on the airtight chamber 13 of the vacuum advance device 12, and the diaphragm 14 receives the suction force due to the negative pressure and the spring 1.
8, the breaker plate 11 of the interrupter 16 is rotated via the rod 15, and the ignition timing is adjusted to correspond to the rotation speed when a high load is applied to the engine. do.

In addition, when the load acting on the engine is low when the engine is rotating at high speed, the engine speed is maintained at a constant opening of the Okel throttle valve 4 in the carburetor 2, compared to when the load is high. As a result, the inflow speed of the fuel mixture becomes even faster than when the load is high, and the negative pressure in the Pl, 22 portion in the fuel mixture intake passage 6 increases, and accordingly, the negative pressure in the negative pressure chamber 8 in the exhaust governor 1 increases. The negative pressure inside will also increase.

Therefore, the governor throttle valve 5 closes further than when the load is high, and its opening degree becomes smaller.

That is, when the load is low, the engine speed increases and the opening degree of the governor throttle valve 5 becomes smaller, so that the negative pressure in 21 portions of the fuel mixture intake passage 6 becomes even higher than when the load is high. Therefore, the difference in negative pressure between the 21st part and the 22nd part becomes even larger.

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 displaced further toward the airtight chamber 13 than when the load is high, and the breaker plate 17 of the interrupter 16 is rotated in the advance direction.

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

In addition, although the spool valve 21 of the switching valve 22 moves as the negative pressure increases at the time of the above-mentioned low load, that is, as the governor throttle valve 5 changes its opening, this movement causes the switching of the vent holes 20as 20b. Not announced.

That is, unless the governor throttle valve 5 is displaced to a closed position where the engine speed is set to 1500 rpm or less, no substantial switching occurs by the switching valve 22.

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 acting on the engine is high or low. It can be controlled to obtain appropriate ignition timing.

Note that the location of the vent hole 20b in the illustrated embodiment is not limited to the intake manifold 3;
The wall of the fuel mixture intake passage 6, that is, the section 21 between the downstream side of the governor throttle valve 5 when the air governor is in the closed position, that is, the top of the peripheral edge of the governor throttle valve 5 and the end of the intake manifold 3. If so, there is no problem with either position.

As described in detail above, the present invention provides ventilation holes communicating with the airtight chamber of the vacuum advance device on the carburetor side and the air governor or intake manifold side, respectively.
By incorporating a switching valve that is linked to the opening and closing operations of the governor throttle valve into the passage connecting the two vent holes and the airtight chamber, the valve can be switched as appropriate. It goes without saying that it is possible to perform advance angle control corresponding to low-speed rotation, and in particular, it is possible to obtain a vacuum advance angle that corresponds to the opening degree of the governor throttle valve. The ignition timing can be appropriately controlled in response to fluctuations in engine speed caused by the engine speed.

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.

α) Excessive temperature rise in exhaust gas can be suppressed, the lifespan of exhaust pipes and mufflers can be extended, overheating can be prevented, and the durability of various parts of the engine can be improved.

(2) Fuel efficiency can be improved.

(3) Impurities in exhaust gas can be reduced.

0) It is possible to prevent a decrease in output.

The present invention also provides a switching valve that selectively communicates two vent holes for controlling the vacuum advance angle with an airtight chamber of the vacuum advance device, and a switching valve that selectively connects the two vent holes for vacuum advance angle control to the airtight chamber of the vacuum advance device. By placing the valves in opposing positions and connecting the valve stem of the switching spool valve to the governor throttle valve together with the piston rod of the negative pressure chamber, the air governor can be made into a compact structure regardless of the installation of the switching valve. There are advantages.

[Brief explanation of drawings]

The drawings are cross-sectional views showing embodiments of the present invention. 1...Air governor, 2...Curved carburetor, 3
・・・・・・Intake manifold, 4・・・・・・
Throttle valve, 5...Governor throttle valve, 6...Curved fuel mixture intake passage, 12...
Vacuum advance angle device, 13...Airtight chamber, 20as20
b...Vent hole for vacuum advance angle control, 22...
...Switching valve, 21...Curved Shoor valve, 28...
...Valve stem.

Claims (1)

[Claims] 1. In a gasoline engine incorporating an air governor between a carburetor and an intake manifold, a fuel mixture intake passage from the upstream side of the throttle valve in the carburetor and the downstream side of the governor throttle valve in the air governor to the end of the intake manifold. Vent holes for vacuum advance control are provided at appropriate positions of the air governor, and the air governor is provided with a switching valve that selectively communicates the two vent holes with the airtight chamber of the vacuum advance device. The valve is set in a position opposite to the negative pressure chamber formed in the air governor for controlling the governor throttle valve, and the valve stem of the spool valve in the switching valve is moved in response to pressure changes in the negative pressure chamber. When the governor throttle valve is in the closed position, the vent hole on the carburetor side communicates with the airtight chamber, and when the governor throttle valve is in the open position, the vent hole on the governor side is connected to the cabana throttle lure (J17 valve) together with the piston lot. A vacuum advance angle control device for a gasoline engine with an air governor, characterized in that the device communicates with an airtight chamber.