JPH0246773B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a throttle valve opening control device.

[Conventional technology]

When the throttle valve is rapidly closed to the idling opening while the vehicle is decelerating, the liquid fuel adhering to the inner wall of the intake manifold evaporates all at once, causing the air-fuel mixture supplied to the engine cylinder to temporarily become over-rich. Thus, there is a problem of misfire. To solve this problem, when the throttle valve is closed to reduce speed, the throttle valve is temporarily held open at a predetermined opening, and then gradually closed to the idling opening. A throttle valve opening control device is known. With this throttle valve opening control device, whether the throttle valve is closed from a large opening or from a small opening, the closing speed when the throttle valve is held open and then gradually closed is approximately constant. However, when the accelerator pedal is lightly depressed and released, that is, when the throttle valve is closed from a small opening and the valve closing speed is relatively fast, combustion becomes unstable and acceleration and deceleration forces are applied to the vehicle. They are added to each other alternately, resulting in deterioration of vehicle drivability. In order to avoid such deterioration in vehicle drivability, it is necessary to maintain stable combustion by slowing down the closing speed of the throttle valve. On the other hand, if the closing speed of the throttle valve is slowed down in this way, the engine brake will not be effective when the throttle valve closes from a large opening, making it dangerous to drive the vehicle. Therefore, when the throttle valve is closed from a large opening degree, it is necessary to increase the closing speed to some extent after the throttle valve is held open.
Therefore, there is a known throttle valve opening control device that changes the closing speed of the throttle valve after the throttle valve is held open in accordance with the throttle valve opening when the throttle valve starts opening. (see publication).

[Problem to be solved by the invention]

By the way, in an internal combustion engine, for example, it is preferable to keep the throttle valve open at a relatively large opening when the engine is started, and to keep the throttle valve open at a relatively small opening after the engine is started until warm-up is completed. . That is, it is preferable to provide a throttle valve opening holding device that can hold the throttle valve open at two different opening degrees. However, there is a problem in that it is actually extremely difficult to provide the throttle valve with such a throttle valve opening holding device in addition to the above-mentioned throttle valve opening control device.

The present invention provides a throttle valve that can change the closing speed of the throttle valve in accordance with the opening degree of the throttle valve when the throttle valve starts closing, and can also maintain the throttle valve open at two different opening degrees. An object of the present invention is to provide an opening control device.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a first negative pressure port that is always open in the intake passage downstream of the carburetor throttle valve, and a first negative pressure port whose throttle valve opening is slightly larger than the idling opening. A second negative pressure port opens into the intake passage downstream of the throttle valve when the opening is smaller than the first set opening, and opens into the intake passage upstream of the throttle valve when the throttle valve opening is larger than the first set opening. a first diaphragm chamber defined by the first diaphragm and further provided with a first spring for pressing the first diaphragm; and a second diaphragm chamber defined by the second diaphragm and further provided with a second spring for pressing the second diaphragm. a throttle valve opening regulating device having a first diaphragm chamber connected to a first negative pressure port via a first throttle and a second diaphragm chamber connected to a second negative pressure port via a second throttle;
A control rod connected to the negative pressure port and engaged with the arm of the throttle valve when the throttle valve closes to a second set opening that is larger than the first set opening is connected to the first diaphragm to operate the throttle valve. When the valve is closed from the second set opening degree to the first set opening degree at the first valve closing speed determined by the first spring and the first throttle, and when the throttle valve further closes to the first set opening degree, A stopper that engages with the first diaphragm is connected to the second diaphragm to move the throttle valve to the second diaphragm.
Throttle valve opening at which the valve is closed from the first set opening to the idling opening at the second valve closing speed determined by the spring and the second throttle, and the first valve closing speed is faster than the second valve closing speed. In the control device, the first
When the diaphragm chamber and the second diaphragm chamber are communicated with the atmosphere through the isolation valves, and the first diaphragm chamber is communicated with the atmosphere by the switching action of the isolation valve, the throttle valve is held open at the second set opening degree. When the second diaphragm chamber is communicated with the atmosphere, the throttle valve is held open at the first set opening degree.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Referring to FIG. 1, 1 is the intake manifold, 2
3 represents a carburetor, 3 represents a throttle valve, 4 represents a throttle shaft, and 5 represents a throttle valve opening regulating device.
The throttle valve opening regulating device 5 includes a first diaphragm 6 and a second diaphragm 7 arranged in tandem.
It further has a first diaphragm chamber 8 isolated from the atmosphere by a first diaphragm 6, and a second diaphragm chamber 9 isolated from the first diaphragm chamber 8 by a second diaphragm 7. A first compression spring 10 for pressing the first diaphragm is inserted into the first diaphragm chamber 8, and a second compression spring 10 for pressing the second diaphragm is inserted into the second diaphragm chamber 9.
A compression spring 11 is inserted. Further, a control rod 12 is fixed to the first diaphragm 6, and the tip of the control rod 12 is arranged so as to be engageable with the tip of an arm 13 fixed to the throttle shaft 4.
Furthermore, a stopper 14 is arranged in the first diaphragm chamber 8 and is engageable with the first diaphragm 6 , and this stopper 14 is connected to the second diaphragm 7 . On the other hand, the intake manifold 1 is formed with a first negative pressure port 16 that is always open into the intake passage 15 downstream of the throttle valve 3, and the carburetor 2 is provided with a first negative pressure port 16 that opens into the intake passage 15 downstream of the throttle valve 3. When the opening degree of the throttle valve 3 is small, it opens into the intake passage 15 downstream of the throttle valve 3, and when the opening degree of the throttle valve 3 is larger than the first set opening degree indicated by the broken line A, the throttle valve 3 opens.
A second negative pressure port 17 that opens into the upstream intake passage 15 is formed. The first diaphragm chamber 8 is connected to the first negative pressure port 16 via a negative pressure conduit 18 and a first restriction 19, and furthermore, the first diaphragm chamber 8
communicates with the atmosphere via a normally closed shutoff valve 20. The solenoid 21 of this cutoff valve 20 is connected to the starter switch 22, and the starter switch 22
When the solenoid 21 is turned on, the solenoid 21 is energized and the cutoff valve 20 is opened. On the other hand, the second diaphragm chamber 9 is connected to the second negative pressure port 17 via a negative pressure conduit 23 and a negative pressure transmission delay valve 24 . This negative pressure transmission delay valve 24 has a second throttle 25 arranged in parallel.
and a check valve 26, which allows flow only from the negative pressure port 17 into the second diaphragm chamber 9. In addition, the second diaphragm chamber 9
On the one hand, it communicates with the atmosphere via an atmospheric conduit 27 and a temperature-sensitive valve 28, which constitutes a shut-off valve, and on the other hand, through an atmospheric conduit 29 and a pressure-sensitive valve 30, which constitutes a shut-off valve. The temperature sensing valve 28 has a temperature sensing portion 32 immersed in the engine cooling water passage 31 and a temperature sensing portion 3 .
2, and an on-off valve 34 operated by the bimetal element 33. In this temperature-sensitive valve 28, when the engine cooling water temperature is above a predetermined temperature, the on-off valve 34 is closed as shown in FIG. The opening/closing valve 34 opens by curving. On the other hand, the pressure sensitive valve 30 includes a piston 36 that responds to the pressure within the power steering hydraulic pressure transmission path 35, and an on-off valve 37 connected to the piston 36. In this pressure-sensitive valve 30, when the power steering oil pressure is smaller than a predetermined pressure, the on-off valve 37 is closed as shown in FIG. Valve 37 opens. Note that the throttle valve 3 is normally biased in the valve-closing direction by a spring (not shown).

If the engine has been warmed up and the steering wheel is not in the stationary position, the shutoff valve 20, temperature-sensitive valve 28, and pressure-sensitive valve 3 are activated.
0, all valves are closed. At this time, throttle valve 3
When the opening degree is large and high load operation is performed, the first diaphragm chamber 8 and the second diaphragm chamber 9
Because the negative pressure inside is extremely small, the first diaphragm 6 and the second diaphragm 7 as shown in FIG.
is in the leftmost position. Next, the throttle valve 3 is closed to reduce the speed, and when the second set opening degree shown by the broken line B is reached, the tip of the arm 13 comes into contact with the tip of the control rod 12. This time is indicated by time T _B in FIG. In FIG. 2, the vertical axis θ indicates the opening degree of the throttle valve 3, and the horizontal axis T indicates time. Therefore, when the throttle valve 3 is located at the position indicated by the broken line B in FIG. 1, the throttle valve opening degree is indicated by θ _B in FIG. on the other hand,
When the throttle valve 3 closes to the position shown by the broken line B in FIG. 1, a large negative pressure is generated within the intake manifold 1, and this large negative pressure is applied to the first negative pressure port 16. Therefore, at this time, the air in the first diaphragm chamber 8 gradually flows out into the intake manifold 1 through the first throttle 19, so that the negative pressure in the first diaphragm chamber 8 gradually increases. the result,
Since the first diaphragm 6 gradually moves to the right against the compression spring 10, the throttle valve 3 gradually closes as shown in FIG. Next, when the throttle valve 3 closes to the position shown by the broken line A in FIG. 1, the first diaphragm 6 comes into contact with the stopper 14 and a large negative pressure is applied to the first negative pressure port 17.
This time is indicated by time T _A in FIG. 2, and the throttle valve opening at this time is indicated by θ _A in FIG. As described above, when a large negative pressure is applied to the first negative pressure port 17, the air in the second diaphragm chamber 9 gradually flows out into the intake passage 15 through the second restrictor 25. The negative pressure gradually increases. As a result, the second diaphragm 7 gradually moves to the right against the compression spring 11, so that the first diaphragm 6 moves toward the stopper 14.
As a result, the second
As shown in the figure, the throttle valve 3 gradually closes toward the idling position. Next, when time T _I is reached in FIG. 2, the throttle valve 3 reaches the idling opening θ _I. As can be seen from FIG. 2, the throttle valve closing speed between times _{TB and TA} is faster than the throttle valve closing speed between times _{TA and TI} . The closing speed of the throttle valve between times T _B and T _A is determined by the first compression spring 10 and the first
The closing speed of the throttle valve between times T _A and T _I is determined by the second compression spring 11 and the second throttle 25 . Therefore, the compression springs 10, 1 are adjusted so that the valve closing speed is as shown in FIG.
A spring force of 1 and an opening area of the apertures 19, 25 are selected. When the opening degree of the throttle valve 3 before closing is large, the opening speed of the throttle valve 3 is fast as shown between time T _B and T _A in Fig. 2, and therefore a good engine braking effect is ensured. can do. On the other hand, if the accelerator pedal is released after being lightly depressed, as soon as the throttle valve 3 crosses the position shown by the broken line A in FIG. Due to the action of atmospheric pressure, the second diaphragm 7 moves to the leftmost position shown in FIG. On the other hand, at this time, the negative pressure inside the intake manifold 1 does not become so small, and even if this negative pressure becomes small temporarily, the negative pressure inside the first diaphragm chamber 8 will decrease because the first throttle 19 is provided. It remains large, so that the first diaphragm 6 remains in contact with the stopper 14. Therefore, as mentioned above, when the accelerator pedal is lightly depressed and then released, the throttle valve 3 gradually closes as shown between times T _A and T _I in FIG. During this period, stable combustion is ensured, so that acceleration and deceleration forces do not alternately act on the vehicle, and good drivability can therefore be ensured.

On the other hand, when the starter motor 22 is turned on to start the engine, the cutoff valve 20 opens, and the inside of the first diaphragm chamber 8 becomes atmospheric pressure. The valve is held open in this position. Further, when the engine cooling water temperature is lower than a predetermined temperature, the temperature-sensitive valve 28 is opened, and when the power steering oil pressure is higher than the predetermined oil pressure, the pressure-sensitive valve 30 is opened.
When either valve opens, the inside of the second diaphragm chamber 9 becomes atmospheric pressure, and the throttle valve 3 is held open at the position indicated by the broken line A in FIG. Conventionally, the throttle valve 3 is slightly opened before warm-up is completed to ensure stable engine operation.
When the steering wheel is turned from the stationary position, the throttle valve 3 is slightly opened to increase the idle. Furthermore, when starting the engine, especially when restarting the engine, the throttle valve is opened more widely than before the engine is warmed up or when the engine is idling up, in order to sufficiently dilute the fuel vapor accumulated in the intake manifold. . In this embodiment, even when the required throttle opening to keep the valve open differs,
The throttle valve can be kept open at the required throttle opening by each throttle valve opening regulating device.

〔Effect of the invention〕

As described above, according to the present invention, when the throttle valve opening degree before the throttle valve closes is large, it is possible to increase the closing speed of the throttle valve to ensure a good engine braking action. When the opening degree of the throttle valve is small, the closing speed of the throttle valve can be slowed down to ensure good vehicle drivability. Furthermore, it is possible to maintain the throttle valve open at different opening degrees by using a throttle valve opening regulating device for controlling the throttle valve closing speed, thus making the throttle valve opening control system much wider than the conventional throttle valve opening control system. It can be simplified to

[Brief explanation of drawings]

FIG. 1 is an overall view of an engine intake system according to the present invention, and FIG. 2 is a diagram showing changes in throttle valve opening. 2... Carburetor, 3... Throttle valve, 5... Throttle valve opening regulating device, 6... First diaphragm, 7... Second diaphragm, 8... First diaphragm chamber, 9... Second diaphragm Room 10...
First compression spring, 11... Second compression spring, 19...
1st aperture, 25...2nd aperture.

Claims (1)

[Claims] 1. A first negative pressure port is provided which always opens into the intake passage downstream of the carburetor throttle valve, and when the throttle valve opening is smaller than the first set opening which is slightly larger than the idling opening, the throttle valve is opened downstream of the throttle valve. A second valve opens into the intake passage and opens into the intake passage upstream of the throttle valve when the throttle valve opening is larger than the first set opening.
a first diaphragm chamber defined by the first diaphragm and including a first spring for pressing the first diaphragm; and a second spring defined by the second diaphragm and for pressing the second diaphragm. and a second diaphragm chamber, the first diaphragm chamber is connected to the first negative pressure port via a first throttle, and the second diaphragm chamber is connected to the first negative pressure port through a second throttle. connected to the second negative pressure port through the
A control rod that engages the arm of the throttle valve when the throttle valve closes to a second set opening that is larger than the first set opening is connected to the first diaphragm, and the throttle valve is connected to the first spring. and the first valve closing speed determined by the first throttle, the valve is closed from the second set opening degree to the first set opening degree, and further, when the throttle valve closes to the first set opening degree, the throttle valve is closed to the first set opening degree. A stopper that engages with the first diaphragm is connected to the second diaphragm, and the throttle valve is moved from the first set opening to the idling opening at a second valve closing speed determined by the second spring and second throttle. In the throttle valve opening control device that closes the valve and makes the first valve closing speed faster than the second valve closing speed, the first diaphragm chamber and the second diaphragm chamber are each communicated with the atmosphere via a cutoff valve, By the switching action of the shutoff valve, when the first diaphragm chamber is communicated with the atmosphere, the throttle valve is held open at the second set opening degree, and when the second diaphragm chamber is communicated with the atmosphere, the throttle valve is opened at the first opening degree. A throttle valve opening control device that keeps the valve open at a set opening.