JPS5854670Y2 - Control valve of flow metering device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control valve used in a device that measures and controls the flow rate of fluid.

In general, there are various types of devices for measuring and controlling the flow rate of this type of fluid, and they are widely used.

Particularly in internal combustion engines such as automobiles, it is important to accurately control the weight ratio of fuel and intake air to a constant value for engine efficiency and exhaust gas countermeasures. measurement equipment is required.

As an example of an attempt to detect the amount of intake air in an internal combustion engine at low cost and with high accuracy,
The device disclosed in Japanese Patent No.-62665 can be mentioned.

This conventional device includes a first valve and a second valve that are arranged in series in a measuring pipe connected to an intake manifold, a pressure setting device that responds to changes in the pressure difference before and after the first valve, and a pressure setting device. The valve opening device drives the first valve using the output from the first valve, and the pressure difference before and after the first valve is always kept constant, and the amount of intake air is detected from the opening degree of the first valve.

However, the pressure setting device opens toward a diaphragm separating an upper chamber and a lower chamber separated by a diaphragm and communicating with the downstream and upstream sides of the first valve, respectively, and a valve plate fixed at one end to the diaphragm. A so-called flat seat valve is used, which is comprised of a pipe connected to a valve opening device at the other end.

In this flat seat valve, the output that passes through the pipe and reaches the valve opening device changes depending on the distance between the valve plate and the open end of the pipe, but the valve plate is fixed to the diaphragm. However, the degree of parallelism to the opening end of the pipe changes slightly during movement, and the opening area of the valve is no longer proportional to the amount of displacement of the diaphragm.

This appears as a deterioration in responsiveness, where changes in the pressure difference acting on the diaphragm do not correspond accurately to the opening area of the valve.

Such a reduction is referred to herein as pressure sensitive hysteresis.

In view of the above points, the present invention has been developed to provide an alignment feature to the pressure-sensitive diaphragm and air valve part, which are the heart of the servo mechanism for controlling the differential pressure before and after the upstream valve (flow rate detection valve) in an air flow measurement device for internal combustion engines. By incorporating a valve mechanism using a ball, the present invention provides a device that significantly reduces pressure-sensitive hysteresis and improves the stability of opening and closing the air valve.

The configuration of this invention will be explained below according to embodiments shown in the drawings.

Note that what is shown in FIGS. 1 and 2 is an embodiment of the present invention applied to an air flow metering device used in a fuel system of an internal combustion engine.

In FIGS. 1 and 2, 1 is an air intake pipe of an engine, and 2 is a feedback control mechanism having a valve opening mechanism 3 and a servo mechanism 4 for differential pressure control.

The air suction pipe 1 is provided with two upstream valves 5 as air throttle valves and a downstream valve 6. For example, one upstream valve 5 is connected to the valve opening mechanism 3 as a flow rate detection valve, and the other downstream valve is connected to the valve opening mechanism 3 as a flow rate detection valve. 6 is connected to the accelerator pedal 7 as a flow control valve.

The air pressure on the upstream side of this upstream valve 5 is Pl, and the air pressure in the intermediate chamber 8 partitioned by the upstream valve 5 and the downstream valve 6 is P2.
Then, by keeping the pressure difference (PI-P2) constant, the air flow rate is proportional to the opening area of the upstream valve 5, and the flow rate can be measured from the opening area of the valve.

This is the so-called area type flow meter system, and the pressure difference (p, -p2) before and after the flow rate detection valve 5 is controlled to be constant by the following feedback control mechanism 2.

That is, when the pressure difference (P - P2) deviates slightly from a certain constant value, the servo mechanism 4 detects and amplifies the deviation, and the output from the servo mechanism 4 is used to adjust the pressure before and after the upstream valve. The valve opening mechanism 3 directly controls the opening and closing of the upstream valve 5 in response to the deviation to correct the set pressure difference (p, -p2) to a constant value.

This valve opening mechanism 3 has a diaphragm 9 installed inside the main body via a spring 10, and an upstream valve 5 connected to a movable portion of the diaphragm 9.

Next, the servo mechanism 4 has an internal differential pressure setting diaphragm 11.
A ball-shaped valve 1, which is an important component of the present invention, is linked to a chamber A and a chamber B separated by a diaphragm 11.
Variable orifice 13 whose opening area changes depending on the displacement of 2.
It has a C room and a D room separated by.

The A chamber and the D chamber communicate with each other and are maintained at the same pressure, the B chamber communicates with an intermediate chamber 8 downstream of the upstream valve 5, and the C chamber communicates with the valve opening mechanism 3 side and a throttle 15. Through intermediate chamber 8
It will be communicated to.

Further, chambers A and D communicate with the upstream side of the upstream valve 5, and the air pressure becomes Pl, and that of chamber B becomes P2, resulting in a pressure difference (
P, -P2) is detected as a displacement of the diaphragm 11 that partitions the A room and the B room.

In the servo mechanism 4, the main factor that determines the control accuracy is the slippage of the operation of the diaphragm 11 and the air valve 12 connected to it, and the frictional resistance of this part is due to the error in the set pressure difference (Pl-P2). It also causes the deterioration of responsiveness.

The frictional force that prevents smooth displacement of these parts is mainly caused by twisting due to poor connections between the diaphragm and air valve.

In addition, twisting of the air valve also causes instability of the opening area of the valve 12, and therefore, in order to improve control accuracy, it is important to have a structure that does not cause assembly errors or twisting.

The present invention solves the above problem by using a ball with alignment properties in the air valve 12 itself, significantly reducing pressure-sensitive hysteresis, and improving control accuracy.

Reference numeral 20 designates an integrally formed valve seat having a cylindrical portion 21 for slidingly guiding the ball valve 12 and a bottom surface 22 having a spherical surface forming a variable orifice 13.

The cylindrical portion 21 and the ball valve 12 are in contact with each other with an extremely small gap, and the bottom surface 22 and the ball valve 12 are set in a slightly open state in a standard differential pressure state.

17 and 18 are springs set to balance the force generated by the pressure difference between air pressures P1 and P2 acting on both sides of the diaphragm 11, and 19 is an adjustment screw for finely adjusting the spring pressure.

In the embodiment shown in FIG. 2, the spring 17 is omitted and the diaphragm 11 is brought into direct contact with the ball-shaped air valve 12.

The operation is the same as the embodiment shown in FIG.

16 is a bellows for correcting the magnitude of the pressure difference (p, -p2) with respect to the specific weight of the inflowing air, that is, the temperature and pressure, in order to make the opening area of the upstream valve 5 proportional to the weight flow rate; A gas having the same temperature and pressure as the atmosphere in the reference state is sealed, one end of which is in constant contact with the valve 12 side, and the other end is fixed to a fixed part of the main body.

In this case, the effective area of the bellows 16 is (standard differential pressure at standard pressure temperature) x (effective area of differential pressure setting diaphragm 11)
It can be calculated as ÷ (standard pressure of sealed gas).

The bellows 16 is not required when the opening area of the upstream valve 5 is made proportional to the volumetric flow rate at atmospheric pressure and atmospheric temperature during operation.

Next, the operating procedure of the apparatus configured as described above will be explained.

For example, when the accelerator pedal 7 is depressed to open the downstream flow rate 6, the pressure P2 in the intermediate chamber 8 decreases, and the diaphragm 11
Since the pressure in chamber B acting on diaphragm 1 also decreases,
1 moves upward to open a variable orifice 13 formed by a ball-shaped valve 12, and Pl
and P2, the pressure inside the C chamber is lowered.

Due to the decrease in the pressure Po, the diaphragm 9 of the valve opening mechanism 3 communicating with the C chamber is displaced in the vertical direction in the drawing, causing the upstream valve 5 to
p, -p2) until the value reaches a certain set value.

Then, when the upstream pressure P1 decreases due to the opening of the upstream valve 5, and the difference between the pressure P1 on the upstream side of the upstream valve 5 acting on the diaphragm 11 and the pressure P2 in the intermediate chamber 8 reaches a certain value, the servo mechanism The operation of 4 is stopped.

As mentioned above, since a fuel control mechanism is provided in conjunction with the upstream valve 5, which is a flow rate detection valve, the fuel flow rate also increases in proportion to the opening degree of the flow rate detection valve 5, and as a result, the fuel control mechanism described above increases. The mechanism can measure the fuel flow rate according to the air flow rate depending on the opening degree of the downstream valve 6, which is a flow rate control valve.

That is, the air-fuel ratio is kept constant.

The device of the present invention measures the flow rate of intake air as described above, but what should be noted is that by using a self-aligning ball in the valve 12 that interlocks with the diaphragm 11 of the servo mechanism 4, Significantly reduces pressure-sensitive hysteresis,
This is because the accuracy of the device has been improved.

In other words, even if the diaphragm slightly fluctuates during its movement, the variable orifice formed between the ball and the seating surface always assumes an annular shape regardless of the displacement of the diaphragm (and therefore also of the ball). (except when fully closed), the displacement of the diaphragm and the opening area of the variable orifice correspond exactly to each other.

Therefore, pressure sensitive hysteresis does not occur.

As explained above, this invention consists of a flow rate detection valve disposed in a fluid flow path, a servo mechanism that responds to changes in the pressure difference before and after the valve, and an open valve that operates the flow rate detection valve according to the output of the servo mechanism. In the area type flow metering device, which comprises a valve mechanism and makes the opening degree of the iron amount proportional to the fluid flow rate by keeping the pressure difference before and after the flow rate detection valve at a predetermined value, the servo mechanism includes:
A chamber communicating with the fluid flow path on the upstream side of the flow rate detection valve, a chamber communicating with the fluid flow path on the downstream side of the flow rate detection valve, a diaphragm partitioning the compartment, a spherical valve interlocking with the diaphragm, and a valve. A control valve for a flow metering device, comprising: a valve seat having a seating surface that cooperates with each other to form a variable orifice that communicates with the valve opening device; and a cylindrical portion that guides the valve. As a result, pressure-sensitive hysteresis can be significantly reduced, and measurement accuracy is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an apparatus according to the present invention, and FIG. 2 is a longitudinal cross-sectional view showing another embodiment. DESCRIPTION OF SYMBOLS 1... Air intake pipe, 2... Feedback control mechanism, 3... Valve opening mechanism, 4...
...Servo mechanism for differential pressure control, 5...
...Upstream valve (flow rate detection valve), 6...Downstream valve (flow rate adjustment valve), 11...Diaphragm, 12...
...Ball-shaped valve.

Claims (1)

[Scope of utility model registration request] It consists of a flow rate detection valve placed in the fluid flow path, a servo mechanism that responds to changes in the pressure difference before and after the valve, and a valve opening mechanism that operates the flow rate detection valve according to the output of the servo mechanism. In an area type flow metering device that makes the opening degree of the valve proportional to the fluid flow rate by maintaining the pressure difference at a predetermined value,
The servo mechanism includes a chamber communicating with the fluid flow path on the upstream side of the flow rate detection valve, a chamber communicating with the fluid flow path on the downstream side of the flow rate detection valve, a diaphragm that partitions the compartment, and a spherical diaphragm interlocking with the diaphragm. a valve seat having a cylindrical portion for guiding the valve and a seating surface that cooperates with the valve to form a variable orifice therebetween leading to the valve opening device;
A control valve for a flow metering device, comprising: