JPH018677Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a negative pressure control device for automobiles, and in particular,
The present invention relates to a negative pressure control device that suppresses an increase in suction negative pressure during deceleration.

In an air valve equipped with an automobile carburetor or fuel injection valve, when the vehicle decelerates from a predetermined operating state, the negative pressure in the intake manifold and the combustion chamber of the cylinder becomes excessive. On the other hand, the negative pressure in the engine crank chamber does not change much regardless of the operating state.
As a result, the differential pressure between the crank chamber and the combustion chamber increases, and engine oil in the crank chamber passes through the gap between the piston rings and enters the combustion chamber, where it is also combusted. Therefore, problems arise in that engine oil is consumed and the composition of the exhaust gas is confused and harmful gases are generated.

FIG. 1 is a cross-sectional view of a negative pressure control device used in a conventional fuel-injected air valve, such as that disclosed in U.S. Pat. No. 4,237,842. A throttle valve 2 installed in the intake passage of the air valve body 1 is attached to a throttle valve shaft 3, and the downstream side of the throttle valve 2 communicates with an intake manifold. The upstream and downstream sides of the throttle valve 2 are directly communicated through a bypass passage 4, and the upstream side has an inlet 6a,
The outlet side is 6b, and the passage cross-sectional area can be adjusted with an adjustment screw 5 in the middle. That is, during idling operation when the throttle valve 2 is at its minimum opening degree, a small amount of air necessary for this is replenished to enable suitable operation.

Further, an air supply path 12 that bypasses the throttle valve 2 is formed on the right side of the air valve main body 1, and an adjustment screw ring 11 is installed above the air supply path 12. This adjustment screw ring 11
An air passage 8 is provided in the center of the air passage 8, and a plate-shaped regulation valve 7 installed at the bottom thereof is pushed up by a coil spring 9 and comes into contact with the seat portion to seal the air passage 8.
The hat-shaped support 10 is fitted into the center of the coil spring 9 to prevent it from buckling, and a plurality of holes 13 are provided in the flange to form air passages.

In the negative pressure control device configured in this manner, during deceleration, the throttle valve 2 is nearly closed, increasing the suction negative pressure downstream thereof. Therefore, at the same time a small amount of air is supplied through the bypass passage 4, the regulating valve 7 is pushed down by overcoming the spring force of the coil spring 9, and the plurality of holes provided in the air passage 8 and the support body 10 are pushed down. A considerable amount of air is supplied via the air supply line 13 and the air supply line 12. As a result, the suction negative pressure is reduced and the negative pressure in the combustion chamber is also reduced, so that the phenomenon of burning engine oil can be prevented. Note that the negative pressure control device is closed during idling operation.

FIG. 2 is a sectional view of a negative pressure control device used in a conventional carburetor, and the same parts as in FIG. 1 are given the same reference numerals. The negative pressure control device in this case is installed between the protrusion of the intake manifold 22 and the pipe 16, and includes a support 10 in which a regulating valve 7, a coil spring 9, and a plurality of holes 13 are provided in the cap 14. It has been installed. Therefore, as in the case of FIG. 1, air can be replenished during deceleration when the negative pressure within the intake manifold 22 becomes large.

In addition, 18 is an intake cylinder, in which a choke valve 17, a bench lily 19 are provided, and a throttle valve 2 is provided.
It communicates with the intake manifold 22 via.
Further, a choke housing 20 is attached to the right side of the intake cylinder 18, and at the same time as the engine is started, a heater therein is energized to heat the spiral bimetal and gradually open the choke valve 17.

The additional air amount Q supplied to the engine can generally be expressed by the following equation.

However, C is the flow coefficient, A is the cross-sectional area of the passage, γ is the specific gravity of the air, and ΔP is the pressure difference when passing through the part A. Note that the cross-sectional area A of the passage is usually set to be large enough to allow passage of an amount of air greater than that required by the engine. Also,
The engine capacity and operating pressure settings differ depending on the vehicle model, but the engine capacity and the amount of additional air are generally proportional.

FIG. 3 is a characteristic diagram of the conventional negative pressure control device shown in FIGS. 1 and 2, in which the horizontal axis shows the negative pressure in the intake manifold downstream of the throttle valve 2 in mmHg;
The vertical axis shows the additional air flow rate in /min. The negative pressure control device opens and closes the seat portion using a regulation valve 7. The regulating valve must be lowered to a certain extent to enlarge the gap before the air that has passed through the opening can sufficiently pass through. For example, as shown by the solid line in FIG. 3, additional air cannot flow sufficiently unless the temperature is -600 mmHg.

However, when the deceleration operation ends and the negative pressure in the intake manifold decreases, the regulating valve 7 rises to close the seat portion. However, there is a mechanical delay in the movement of the regulation valve 7, and the regulation valve 7 does not rise immediately. Furthermore, the pressure state is unstable during deceleration, and the regulation valve 7 cannot be raised smoothly.

Therefore, even if the pressure reaches -600 mmHg, the regulating valve 7 will allow additional air to pass through, and the negative pressure will further approach atmospheric pressure, for example, as shown by the broken line in Fig. 3, -
It becomes 580mmHg. This kind of hysteresis also differs depending on the speed of deceleration, and the pressure difference
The pressure could reach as high as mmHg, making stable negative pressure control impossible. Another disadvantage is that the valve sometimes moves close to the negative pressure generated during idling and opens during idling after deceleration, increasing the engine's idling speed.

The purpose of this invention is to provide a negative pressure control device that can significantly reduce the hysteresis phenomenon through relatively simple modification.The main feature of this device is that the installation position of the seat section can be adjusted. In addition to being provided at the center of the adjusting screw ring, a constriction portion having an opening area smaller than the opening area of the seat portion is formed on the upstream side of the seat portion.

FIG. 4 is a sectional view of a negative pressure control device according to an embodiment of the present invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals. In this case, the adjustment screw ring 11 is provided with a constriction portion 15 having a diameter d that regulates the maximum air flow rate, and is formed to have a smaller diameter than the conventional opening diameter D. As mentioned above, the air replenishment piping 16 and air path 8 are generally constructed so that they can pass more than the required maximum amount of air, so even if the throttle section 15 is provided, the required amount of air can be obtained. .

The additional air flow rate is determined by the diameter d, and the moving distance of the regulating valve 7 is determined by the additional air flow rate and the diameter D. However, if d/D is smaller than 1, the moving distance of the regulating valve 7 is Therefore, the mechanical delay in the operation of the regulating valve 7 becomes smaller. That is, the valve opens when the set negative pressure is slightly exceeded. Further, when the negative pressure decreases, the regulating valve 7 is closed even if it rises slightly. Furthermore, the portion having the diameter D functions as a surge tank, and pressure fluctuations during depressurization are reduced, allowing smooth movement of the regulating valve 7.

In this way, since the mechanical delay is reduced, the regulating valve 7 can quickly stop the inflow of additional air when the set negative pressure is returned to, thereby preventing a drop in negative pressure and reducing hysteresis. That is, the distance between the solid line and the broken line shown in FIG. 3 is significantly reduced, and the hysteresis phenomenon is suppressed. Note that since the adjusting screw ring 11 is movable, the spring force of the coil spring 9 that presses the regulating valve 7 can be finely adjusted. Therefore, the opening/closing negative pressure of the regulating valve 7 can be finely adjusted, and the hysteresis phenomenon can be reduced.

FIG. 5 is a diagram showing the relationship between the shape of the adjusting screw ring in FIG. 4 and the amount of hysteresis, where the horizontal axis shows the value of d/D and the vertical axis shows the amount of hysteresis in mmHg. This figure is a diagram obtained through experiments, and shows that when d/D becomes 0.8 or less, the amount of hysteresis decreases rapidly. However, setting the value of d/D to 0.8 or less will reduce the maximum air amount, so it must be determined in consideration of the type and size of the air valve to which this negative pressure control device is installed.

As shown in Fig. 2, some conventional negative pressure control devices have a constriction part 15 in the air introduction pipe 16, but depending on the vehicle type, a pipe 16 with an appropriate constriction may be selected and installed. When doing so, the diameter of the aperture must be checked each time, and this poses a problem in that it is difficult to manufacture. However, in the case of Fig. 4, the inner diameter of the adjusting screw ring 11 is simply machined into two stages.
It has the advantage of being inexpensive to manufacture.

In addition, as a method of reducing the amount of movement of the regulating valve 7 when the valve is opened, the connecting portion to the intake manifold 22,
That is, although it is conceivable to provide a throttle downstream of the regulation valve 7, this cannot be adopted because the regulation valve 7 would operate slowly.

The negative pressure control device of this embodiment reduces the hysteresis when the regulating valve opens and closes by narrowing the upstream side of the seat part of the adjusting screw ring that contacts the regulating valve to a diameter of 80% or less. Pressure control accuracy can be improved. Therefore, during deceleration driving, air is quickly replenished to restore the air-fuel ratio of the air-fuel mixture, improving the drivability of the vehicle, as well as purifying the exhaust gas composition and reducing fuel consumption. .

The negative pressure control device of the present invention has the effect of reducing the hysteresis phenomenon during deceleration and improving driveability by simply modifying the inner diameter of the adjusting screw ring into two stages.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a negative pressure control device used in a conventional fuel injection air valve, Figure 2 is a cross-sectional view of a negative pressure control device used in a conventional carburetor, and Figure 3 is a cross-sectional view of a negative pressure control device used in a conventional fuel injection air valve. Figure 2 is a characteristic diagram of a conventional negative pressure control device, Figure 4 is a sectional view of a negative pressure control device that is an embodiment of the present invention, and Figure 5 is the shape and amount of hysteresis of the adjusting screw ring in Figure 4. FIG. 1... Air valve body, 2... Throttle valve, 7... Regulation valve, 8... Air path, 9... Coil spring, 10...
Support body, 11... Adjustment screw ring, 12... Air supply path, 13... Hole, 15... Throttle part, 16... Piping, 22... Intake manifold.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. An air supply path that bypasses the throttle valve and communicates the upstream side of the throttle valve with the intake manifold side, a seat section that serves as an air inlet of this air supply channel, and a seat section that faces the seat section. and a plate-shaped regulation valve that is installed in the air supply path and pushed up by an elastic member, and when the engine intake negative pressure rises above a set value, the regulation valve closes to the seat. In a negative pressure control device that operates to introduce air away from the part and reduce the suction negative pressure,
An adjustment screw ring is provided to enable adjustment of the installation position of the seat part, and a diaphragm part having an opening area smaller than the opening area of the seat part is formed on the upstream side of the seat part. Negative pressure control device. 2. Negative pressure control according to claim 1, wherein the value of d/D is 0.8 or less, where d is the diameter of the throttle part of the adjusting screw ring and D is the diameter of the seat part. Device.