JPH0531228Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a deceleration control device for an internal combustion engine.

Conventional Technology Recently, in internal combustion engines for automobiles, as part of exhaust gas countermeasures, deceleration control devices are often used that prevent the generation of unburned gas (HC) by controlling the closing of the throttle valve when the engine decelerates. has been done.

FIG. 5 shows an example of a deceleration control device using a dart pot. Briefly, when the throttle valve 2 disposed in the intake passage 1 closes during engine deceleration, the throttle valve arm 3 closes the rod 5 of the dart pot 4 at a certain opening degree.
Upon hitting the tip, the air in the atmospheric chamber 7 is compressed via the diaphragm 6 inside the dart pot 4. This compressed air is gradually discharged from the atmospheric chamber 7 through the small ventilation hole 8, so that the throttle valve 2 is gradually closed in conjunction with this.
As a result, a sudden decrease in the amount of intake air sent to the combustion chamber is prevented, and the emission of unburned gas such as HC due to the enrichment of the air-fuel ratio is effectively prevented.

Problems to be Solved by the Invention However, in the conventional deceleration control device described above, the position (touch opening amount) at which the arm 3 of the throttle valve 2 begins to touch the tip of the rod 5 of the dart pot 4 is constant; The opening position of the throttle valve 2 at which deceleration control is started is always constant regardless of engine temperature or operating conditions. Therefore, if the above-mentioned touch opening amount is set to a relatively small value, for example after warm-up, stable engine rotation can be obtained during no-load steady operation when the engine is cold, but the If you dry-infuse, the throttle valve 2 closes suddenly during deceleration, so the fuel droplets adhering to the inner wall of the intake passage rapidly evaporate, the air-fuel ratio becomes richer, and the engine speed fluctuates wildly. In some cases, the engine may stall.

On the other hand, if the touch opening amount is set relatively large in accordance with when the engine is cold, there is a problem that a quick deceleration effect cannot be obtained during deceleration after warming up.

Therefore, for example, as described in Japanese Utility Model Application Publication No. 127435/1987, there are techniques that control the return speed of the throttle valve depending on the engine temperature, but these techniques are similar to the conventional ones. As long as the opening position of the throttle valve at which deceleration control is started is always constant, this method cannot sufficiently solve the above problem.

Means for solving the problem This invention consists of a first
a second diaphragm; a rod fixed to the first diaphragm and having a tip connected to the throttle valve arm; an atmospheric chamber defined by the casing and the first diaphragm and penetrated by the rod; An air chamber defined by the first and second diaphragms and open to the atmosphere through a small hole, and a negative pressure outlet defined by the casing and the second diaphragm and downstream of the throttle valve. a negative pressure chamber communicating with the air chamber; a first set spring disposed in the air chamber to bias the first diaphragm toward the atmospheric chamber; and a first set spring disposed in the negative pressure chamber to bias the second diaphragm toward the air chamber. a second set spring that urges; and an interlocking mechanism that is disposed between the first diaphragm and the second diaphragm and that integrally pulls up the first diaphragm as the second diaphragm moves toward the negative pressure chamber; The engine is characterized by comprising a passage switching mechanism that selectively communicates the negative pressure chamber with the negative pressure outlet or the atmosphere based on the temperature of the engine.

Operation This invention with the above configuration is to variably control the opening position of the throttle valve at the start of closing control during deceleration in accordance with the temperature change of the engine. That is, when the machine is cold, atmospheric pressure is introduced into the negative pressure chamber via the passage switching mechanism, so the second diaphragm is biased toward the air chamber by the second set spring, thereby causing the first diaphragm to switch to the first diaphragm. The set spring pressure urges the rod toward the atmospheric chamber, and the rod reaches its maximum protrusion. Therefore, the throttle valve arm and the rod come into contact from the relatively large opening position of the throttle valve, and the throttle valve slowly closes from the large opening position, thereby providing sufficient deceleration control.

On the other hand, after warming up, a large suction negative pressure is introduced into the negative pressure chamber by the passage switching mechanism, so the second diaphragm is largely displaced toward the negative pressure chamber against the second set spring pressure. Along with this, the first diaphragm is also pulled up toward the negative pressure chamber via the interlocking mechanism, and the rod is retreated to a predetermined amount. Therefore,
The arm and rod begin to come into contact at a relatively small opening position of the throttle valve, that is, the throttle valve rapidly closes to a small opening position, and thereafter slow deceleration control is performed.

Embodiment FIG. 1 shows a first embodiment of this invention, in which 11 is a throttle valve disposed in an intake passage 12 of a carburetor, and 13 is a shaft 1 of the throttle valve 11.
A throttle valve drum 15 is fixed to the outer end of the throttle valve drum 13 and is fixed to the outer end of the throttle valve drum 13, and 15 is a throttle valve arm fixed to the outer end of the throttle valve drum 13. A negative pressure outlet 16 is formed downstream of the opening.

In the figure, 17 is a dart pot fixed to the carburetor, and this dart pot 17 includes a first diaphragm 21 that defines an atmospheric chamber 19 and an air chamber 20 in a casing 18, and a first diaphragm 21 that defines an atmospheric chamber 19 and an air chamber 20, and a first diaphragm 21 that defines an atmospheric chamber 19 and a negative pressure chamber. A second diaphragm 23 defining a diaphragm 22 is provided. Further, the first diaphragm 21 is provided with a small hole 24 that communicates the atmospheric chamber 19 and the air chamber 20, and the base of a rod 25 whose tip passes through the atmospheric chamber 19 and is linked to the arm 15. The ends are fixed. Further, the air chamber 20 is provided with an annular first stopper 26 for regulating the maximum displacement of the second diaphragm 23 toward the air chamber 20. side, the first diaphragm 23 has a relatively small spring pressure that biases the second diaphragm 23 toward the negative pressure chamber 22, respectively.
A set spring 27 is placed in a compressed state. On the other hand, the negative pressure chamber 22 has a second diaphragm 23 inside that regulates the maximum displacement of the second diaphragm 23 toward the negative pressure chamber 22 side.
A stopper 28 is screwed to the upper end wall of the casing 18 so that it can move forward and backward, and the second diaphragm 23
A second set spring 29, which has a relatively large spring pressure and biases the spring toward the air chamber 20, is arranged in a compressed state. Further, numerals 30 and 31 in the figure are a shaft member and a guide member that constitute an interlocking mechanism. The shaft member 30
The base end is fixed to the upper end surface of the first diaphragm 21, and a flange-like locking portion 30a is provided at the free end, and the member slides inside the guide member 31 provided on the lower end surface of the second diaphragm 23. The guide member 31 is movably inserted through the guide member 31, and a locking portion 30a locks on the bent lower end of the guide member 31 so that the guide member 31 can be pulled upward.

In the figure, 32 is a temperature-sensitive valve that constitutes a passage switching mechanism, and this temperature-sensing valve 32 is connected to a cooling water passage 33 of the engine.
The valve body 36 is disposed facing the valve case 34 and supported by a bimetal 35 within the valve case 34. This valve body 36 is located between the first port 37 and the second port 38 of the valve case 34, and opens the first port 37 when the temperature is below a predetermined temperature and opens the second port 38 when the temperature is above a predetermined temperature. The first port 37 is connected to the atmosphere through an air filter 39, and the second port 38 is connected to the pressure passage 40.
It communicates with the negative pressure outlet 16 via. Also,
The inside of the valve case 34 communicates with the negative pressure chamber 22 via a pressure passage 41. In the figure, reference numeral 42 denotes a check valve disposed in the middle of the pressure passage 40.

The operation of this embodiment will be explained below. First, when the engine is cold and the temperature is below the operating temperature of the temperature-sensitive valve 32, the valve element 36 of the temperature-sensitive valve 32 opens the first port 37 as shown in the figure, so there is no air inside the negative pressure chamber 22. , atmospheric pressure from an air filter 39 is introduced. Therefore, the second diaphragm 23 is lowered to the first stopper 26 by the pressure of the second set spring 29, and accordingly, the first diaphragm 21 is also lowered by the first set spring 27.
As a result, the rod 25 is pressed against the atmospheric chamber 19, and the rod 25 is placed at the maximum lowered position.
When the throttle valve 11 is returned to the closing direction in such a state, the arm 15 starts to hit the tip of the rod 25 from a relatively large opening position, and the air in the air chamber 20 is compressed by the first diaphragm 21, causing a small It gradually escapes from the hole 24. As a result, the throttle valve 11 slowly closes from a relatively large opening position as shown in FIG. 2A. For this reason, not only does a proper air-fuel ratio prevent the generation of unburned gas, but even if so-called dry blowing is performed under no-load conditions, rotational fluctuations due to enrichment of the air-fuel ratio, etc. This prevents engine stalls from occurring.

On the other hand, when the engine temperature reaches or exceeds the operating temperature of the temperature-sensitive valve 32, that is, after warming up, the valve body 26 reverses and opens the second port 38. A large negative pressure generated downstream of the tutle valve 11 is introduced from the negative pressure outlet 16.
Therefore, the second diaphragm 23 is displaced toward the negative pressure chamber 22 against the pressure of the second set spring 29,
The shaft member 30 is pulled up to the second stopper 28 position (h length), and the shaft member 30 is pulled up to the locking portion 30a.
Since the first diaphragm 21 is pulled up by the guide member 31 via the first diaphragm 23, the first diaphragm 21 is also displaced toward the air chamber 20 side together with the second diaphragm 23, and is raised by a length h. Therefore, when the throttle valve 11 is returned to the closing direction, the arm 15 hits the tip of the rod 25 from the small opening position, and from this point on, the air in the air chamber 20 gradually escapes.
As a result, the throttle valve 11 rapidly closes to a small opening position as shown in FIG. This provides a rapid deceleration effect.

FIG. 3 shows a second embodiment of this invention. In this embodiment, the initial load of the first set spring 27 is made stronger than in the first embodiment by an amount corresponding to the length _h1 , and The structure is such that the second stopper 28 is moved back by _h1 . Therefore, the temperature sensitive valve 32
If the operating temperature is below the throttle valve 11
When the arm 15 is returned to the closing direction, the initial contact position between the arm 15 and the rod 15 is the same as in the first embodiment, as shown in FIG.
The pressure causes the throttle valve 11 to close more slowly. Therefore, the effect of preventing the air-fuel ratio from becoming richer becomes greater.

After warming up, the second diaphragm 23 is lifted by the length h ₁ +h due to negative pressure, but the rod 2
5, since the lift amount is the length h, the initial load of the first set spring 27 is the same as in the first embodiment, and the same throttle valve opening characteristic as in FIG. 2B is obtained.

FIG. 4 shows a third embodiment of this invention, in which the path switching mechanism is constructed using an electronic control circuit. That is, the water temperature sensor signal 50 and the suction negative pressure signal 51 are input to the control unit 52, where they are outputted to the three-way solenoid valve 53 via the discrimination circuit and the drive circuit, and when the cooling water temperature is below the set temperature and the suction negative pressure is When the set value is exceeded, an AND circuit is established, and at this point, the drive circuit is turned off and atmospheric pressure is introduced into the negative pressure chamber 22.
After warming up and when the suction negative pressure is above the set value, the drive circuit is turned on to drive the three-way solenoid valve 53 and the negative pressure chamber 2
2 is adapted to introduce a large suction negative pressure. With such a configuration, the throttle valve 11
Even more precise closing control is possible. In the figure, 54 is a valve body, 55 is a first port, 56 is a second port, and 57 is an air filter.

In addition to the above-mentioned embodiments, it is also possible to configure the touch opening degree to be increased when the cooling water temperature is below the set temperature and during air-fuel ratio feedback control or exhaust gas recirculation.

Note that the first and second set springs 27, 2
It goes without saying that the opening characteristic of the throttle valve 11 can be arbitrarily set by changing the initial load of the throttle valve 9.

Effects of the invention As is clear from the above explanation, according to the deceleration control device for an internal combustion engine according to the invention, the opening position at the start of closing control of the throttle valve during deceleration can be varied according to engine temperature changes. For example, when the engine is cold, the closing operation can be controlled from a relatively large throttle valve opening position, which not only prevents the generation of unburned gas, but also prevents rotational fluctuations and engine stalling when revving. can be definitely prevented. As a result, the rotational speed during no-load steady operation can be set sufficiently low, and therefore fuel consumption and noise can be reduced. On the other hand, after warming up,
Since the closing operation can be controlled from a small opening position of the throttle valve, a rapid deceleration effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing a first embodiment of a deceleration control device according to this invention, Fig. 2 is an opening characteristic diagram of a throttle valve, and Fig. 3 is an overall configuration diagram showing a second embodiment of this invention. 4 are overall configuration diagrams showing a third embodiment of this invention, and FIG. 5 is a sectional view showing a conventional deceleration control device. 11... Throttle valve, 15... Throttle valve arm, 16... Negative pressure outlet, 17...
Dash pot, 18...Casing, 19...
Atmospheric chamber, 20... Air chamber, 21... First diaphragm, 22... Negative pressure chamber, 23... Second diaphragm, 24... Small hole, 25... Rod, 27... First set spring, 29 ... Second set spring, 30 ... Shaft member (interlocking mechanism), 31 ... Guide member (interlocking mechanism), 32 ... Temperature-sensitive valve (passage switching mechanism).

Claims (1)

[Scope of utility model registration request] defined by first and second diaphragms disposed within a casing, a rod fixed to the first diaphragm and having a tip connected to the throttle valve arm, the casing and the first diaphragm, and An atmospheric chamber penetrated by the rod,
defined by the first and second diaphragms,
and an air chamber opened to the atmosphere through a small hole, defined by a casing and a second diaphragm,
and a negative pressure chamber communicating with a negative pressure outlet downstream of the throttle valve; a first set spring disposed in the air chamber to bias the first diaphragm toward the atmospheric chamber; and a first set spring disposed in the negative pressure chamber. a second set spring that biases the second diaphragm toward the air chamber;
an interlocking mechanism that is disposed between the first diaphragm and the second diaphragm and that integrally pulls up the first diaphragm as the second diaphragm moves toward the negative pressure chamber; A deceleration control device for an internal combustion engine, comprising a passage switching mechanism that selectively communicates the pressure chamber with the negative pressure outlet or the atmosphere.