JPS632018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an emission control device for an internal combustion engine in an automobile or the like.

This type of device includes a solenoid valve that controls the opening and closing of an evaporated fuel discharge path that connects a fuel reservoir such as a fuel tank or a carburetor float chamber with the engine's intake system, and a control valve for a throttle opener when the vehicle speed reaches a predetermined low speed or higher. Some devices are equipped with independent solenoid valves for controlling the operation of the two solenoid valves, but since two solenoid valves are used, not only does the cost of the device increase, but also the control system becomes complicated.

In view of the above points, it is an object of the present invention to provide the emission control device described above, in which one solenoid valve is used for both control systems, thereby reducing the cost of the device and simplifying the control system. purpose.

In order to achieve this purpose, the present invention
A normally closed negative pressure operated valve that opens when activated is installed in the evaporative fuel discharge path that communicates the fuel reservoir such as a float chamber with the engine intake system. A check valve that prevents transmission of negative pressure from the negative pressure responsive valve to the intake pipe side is interposed in the middle of the negative pressure passage for introducing the negative pressure, and the check valve and a communication passage that connects the throttle opener control valve to the upstream side of the check valve in the negative pressure passage, and connects the negative pressure passage,
Between the detour and the communication path, there is a first position that allows the communication path to communicate with the detour and shuts it off from the upstream side of the check valve of the negative pressure path, and a check valve of the negative pressure path that connects the communication path to the negative pressure path. A solenoid valve is provided that can take a second position that communicates with the upstream side and blocks the detour from the detour, and the solenoid valve includes:
A vehicle speed switch is connected to hold this in the first position when the vehicle speed is less than a predetermined value, and in the second position when the vehicle speed exceeds a predetermined value. The feature is that an orifice is interposed between them to provide constant communication between them.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes an internal combustion engine, and an emission control device 6 is connected to an intake pipe 4 located downstream of a throttle valve 3 of a carburetor 2 via a pipe 5. . An evaporated fuel storage device 9 and a throttle opener control valve 10 are connected to two pipes 7 and 8 extending from the emission control device 6, respectively.

The emission control device 6 has a first communication hole 12 formed in the device body 11, one end of which communicates with a conduit 5 connected to the intake pipe 4, and the other end communicated with a conduit 7 connected to the evaporated fuel storage device 9. These pipes 5, 7 and the first communication hole 12 form a negative pressure passage _P1.
is formed. A check valve accommodating chamber 13 is formed in the middle of the first communication hole 12, and a check valve 16 including a valve body 14 and a return spring 15 is accommodated therein. The check valve 16 is designed to only allow negative pressure to be transmitted from the upstream side of the negative pressure passage _P1 , that is, the intake pipe 4 side serving as a negative pressure source, to the downstream side of the negative pressure passage _P1 , that is, the pipe line 7 side. It is always biased in the closing direction by a return spring 15.

A detour _P2 that bypasses the check valve ₁₆ is connected in parallel to the negative pressure passage P1, and furthermore, on the upstream side of the check valve 16 in the negative pressure passage _P1 , that is, on the intake pipe 4 side,
Communication path connected to throttle opener control valve 10
P ₃ is connected.

A three-way solenoid valve 22 built into the device main body 11 is provided between the negative pressure passage P ₁ , the bypass path P ₂ , and the communication path P ₃ . A valve chamber 19, a valve body 25 accommodated in the valve chamber 19, a solenoid 23 surrounding a movable core portion 24 that is integrated with the valve body 25, and a return spring 26 that urges the valve body 25 downward. The valve body 25 is a check valve ₁ of a communication passage _P3 and a negative pressure passage P1.
6, the communication hole 20 with the upstream side can be opened and closed by the lower end, and the communication hole 21 with the communication path _P3 and the detour _P2 can be opened and closed by the upper end. Thus, when the solenoid 23 is de-energized, the valve body 25 of the solenoid valve 22 is in the lower position, that is, the first position, where the communication hole 20 is closed and the communication hole 21 is opened, as shown in the figure.
Further, when the solenoid 23 is energized, it is configured to be held at an upper position, that is, a second position, where the communication hole 21 is closed and the communication hole 20 is opened. Further, a vehicle speed switch 28 is connected to the solenoid 23, which closes when the vehicle speed exceeds 20 km/h and energizes the solenoid 23 from a power source 27, and opens when the vehicle speed is less than 20 km/h.

The device body 11 is provided with an orifice 30 that communicates the upstream side of the check valve 16 in the negative pressure passage _P1 , that is, the intake pipe 4 side, and the inside of the valve chamber ₁₉ . 16 Upstream side and communication path P ₃
is in constant communication.

Float 3 as a fuel reservoir of the evaporated fuel storage device 9
1 is connected to the carburetor 2 via a fuel passage 33. The space above the fuel oil level in the float chamber 32 and the storage container 35 containing activated carbon and other evaporated fuel adsorbents 34 are each connected to a negative pressure operated valve 36.
The valve accommodating chamber 38 formed in the valve box 37 and the communication hole 39 communicating therewith are communicated via pipes 40 and 41. A negative pressure responsive part 4 is provided on the outer surface of the valve case 37.
2 is provided, and the inside of the negative pressure responsive valve 42 is divided into a first pressure receiving chamber 441 and a second pressure receiving chamber ₄ by a diaphragm 43.
It is defined as 4 ₂ . The inside of the second pressure receiving chamber 44 ₂ is communicated with a conduit 7 connected to the emission control device 6 .

A valve body 45 is housed in the valve housing chamber 38 , and a valve rod 46 integrated with the valve body 45 is inserted into the first pressure receiving chamber 44 ₁ through the insertion hole 39 , and the diaphragm 43
connected to. A return spring 47 is contracted in the second pressure receiving chamber 44 ₂ , and its elastic force causes the valve body 45 to press against the first valve seat 49 ₁ formed at the edge of the atmosphere communication hole 48 that opens into the valve housing chamber 38 . energized towards. A second valve seat 49 ₂ is formed at the edge of the insertion hole 39 that opens into the valve housing chamber 38 , and the valve body 45 is reciprocated between the two valve seats 49 ₁ and 49 ₂ by the negative pressure responsive portion 42 . The atmosphere communication hole 48 is connected to the engine 1 through an evaporated fuel discharge path 50.
It communicates with the air cleaner 51 of the intake system.

Inside the valve box 52 of the throttle opener control valve 10, a pressure receiving chamber 5 is formed by a partition wall 54 having a valve hole 53.
5 ₁ and an output negative pressure chamber 55 ₂ , and a pressure receiving chamber 55
₁ is a conduit 8 connected to an emission control device 6,
Further, the inside of the output negative pressure chamber 55 ₂ is communicated with a negative pressure chamber of a known throttle opener 57 via a conduit 56 . In addition, the output negative pressure chamber 55 ₂ has an orifice 58
The air filter 59 is connected to the atmosphere through the orifice 58, and an air filter 59 is installed in the atmosphere opening of the orifice 58. The amount of restriction of the orifice 58 is set to be smaller than the amount of restriction of the orifice 30 of the emission control device 6.

The opening end of the valve hole 53 on the output negative pressure chamber 55 ₂ side is formed in a conical valve seat 60 , and a hemispherical umbrella portion 62 of an umbrella-shaped valve body 61 engages with the conical valve seat 60 , and the valve rod 63 faces the partition wall 54 . and is connected to a diaphragm 64 stretched over one side of the pressure receiving chamber ₅₅₁ .

The valve case 52 also includes the diaphragm 64.
A cylindrical cover 65 is arranged in series to sandwich the periphery of the
A valve body 6 is connected to the inside through a vent hole 66.
A bellows-type air pressure sensing member 67 for applying a closing force according to the level of air pressure is housed in the air pressure sensor 1 . As is well known, the air pressure sensing member 67 is made of an elastic plate and has a vacuum inside, and mounting brackets 69 are provided on both sides of the member 67 to swingably connect the bases of hook members 68 and 68'. , 69' are welded. One hook member 68 is the valve rod 61
The other hook member 68' is locked to a support member 70 provided on the end wall of the cover 65. Support member 70
In the illustrated example, the adjustment bolt is configured as an adjustment bolt, and by rotating it and moving it back and forth appropriately in the axial direction, a constant tensile load is applied to the air pressure sensing member 67, and the tensile force causes the valve body 61 to move toward the valve seat 60. can be held in the seated or closed position.

On the other hand, atmospheric pressure always acts on the pressure sensing member 67 as a compressive force, and is loaded by the closing force of the valve body 61. Therefore, when there is a change in atmospheric pressure, for example when the engine is operated at a high altitude where the atmospheric pressure is low, the closing force of the valve body 61 decreases as the compressive force on the atmospheric pressure sensing member 67 decreases. In other words, the pressure sensing member 67 is the valve body 6
The closing force of 1 can be automatically adjusted in proportion to atmospheric pressure.

Next, the operation of this embodiment will be explained.

(a) When the engine is stopped The inside of the intake pipe 4 of the engine 1 is maintained at atmospheric pressure, and the electromagnetic valve 22 of the emission control device 6 is in a de-energized state, so the valve body 25 is opened by the elastic force of the return spring 26. The hole 20 is closed and the communication hole 21 is opened.

Therefore, atmospheric pressure is the check valve 16 in the negative pressure passage _P1 .
Upstream side, orifice 30, valve chamber 19, gap S,
It is introduced into the second pressure receiving chamber 44 ₂ of the negative pressure operating valve 36 through the communication path 21 , the detour path P ₂ , and the downstream side of the check valve 16 of the negative pressure path P ₁ , and the valve body 45 is connected to the return spring 4 .
7 seats on the first valve seat 49 ₁ and closes the atmosphere communication hole 48 . Therefore, float chamber 3
The fuel evaporated from 2 is not discharged to the evaporated fuel discharge path 50 side, but is led to the storage container 35 through the pipe 40, the valve housing chamber 38, the insertion hole 39, and the pipe 41, and is adsorbed by the adsorbent 34. Ru.

On the other hand, atmospheric pressure is introduced into the pressure receiving chamber ₅₅₁ of the throttle opener control valve 10 through the fourth communication passage 29 of the emission control device 6 and the pipe line 8, and the valve body 61 seats on the valve seat 60 and opens the valve hole 53. Since it is closed, control valve 10 is inoperative.

(b) When the engine is running, but when the vehicle speed is less than 20 km/h When the engine 1 is running, intake negative pressure is generated in the intake pipe 4, and this negative pressure passes through the negative pressure passage _P1 to the negative pressure operating valve 36. It is introduced into the second pressure receiving chamber ₄₄₂ . At this time, the solenoid valve 22 is maintained in the switched state when the vehicle speed is less than 20 km/h and the engine is stopped, so the communication passage 21 is opened by the valve body 25, and therefore the negative pressure passage P ₁ check valve 16
Although it is not possible to contain the maximum intake negative pressure on the downstream side, when the vehicle speed is less than 20 km/h, the opening degree of the throttle valve 3 is small and the generated intake negative pressure does not decrease drastically. The diaphragm 43 responds and moves the valve body 45 away from the first valve seat 49 ₁ to open the atmosphere communication hole 48 . As a result, the evaporated fuel in the float chamber 32 is transferred to the atmosphere communication hole 4.
8. The evaporated fuel is led to the air cleaner 51 after closing the evaporated fuel discharge path 50 and introduced into the engine 1 along with the air, so there is no risk of air pollution.

The intake negative pressure that passed through the orifice 30 is
It is also introduced into the pressure receiving chamber ₅₅₁ of the throttle opener control valve 10 via the communication path 29 and the pipe line 8.
Even if the diaphragm 64 responds against the closing force of the pressure sensing member 67 and the valve body 61 opens the valve hole 53, the degree of restriction of the orifice 58 is smaller than that of the orifice 30, so the output negative pressure chamber 55 Since the intake negative pressure introduced into the valve ₂ immediately leaks to the atmosphere from the orifice 58, the throttle opener 57 is not operated.

(c) When the engine is running, but when the vehicle speed is 20 km/h or more When the vehicle speed becomes 20 km/h or more, the vehicle speed detection switch 28 closes and the solenoid 23 of the solenoid valve 22 closes.
is energized, the movable core portion 24 is attracted by the solenoid 23, and the valve body 25 opens the communication hole 20 and closes the communication hole 21 at the same time. Therefore, the downstream side of the check valve 16 of the negative pressure passage _P1 , that is, the negative pressure operated valve 3
The maximum intake negative pressure can be contained in the second pressure receiving chamber 44 ₂ of No. 6, and the diaphragm 43 responds to this, so that the valve body 45 is seated on the second valve seat 49 ₂ . If the intake negative pressure decreases, the check valve 16 immediately closes the negative pressure inlet 17.
The inside of the second pressure receiving chamber 44 ₂ is maintained at the maximum intake negative pressure by the check valve 16, and the valve body 45 is pressed against the first valve seat 49 ₁
Therefore, the float chamber 3
By making the space inside 2 communicate with the evaporated fuel discharge path 50, the fuel can be sucked out from the float chamber 32 without any trouble.

On the other hand, the intake negative pressure is mainly caused by the communication hole 20 and the valve chamber 1.
9. Since the air is introduced into the pressure receiving chamber ₅₅₁ of the throttle opener control valve 10 through the communication path _P2 , if the throttle valve 3 is then suddenly closed and a sudden deceleration operation is started, the intake negative pressure increases rapidly. The pressure immediately acts on the diaphragm 64, and the valve body 61 moves away from the valve seat 60 against the closing force of the air pressure sensing member 67 to open the valve hole 53. As a result, the pressure receiving chamber 5
The intake negative pressure in ₅₁ is introduced into the output negative pressure chamber 552 through the valve hole ₅₃ , and the throttle opener 57 is operated to forcibly open the throttle valve 3 of the engine 1 to an opening slightly larger than the idle opening. However, by suppressing an excessive decrease in charging efficiency, misfires can be prevented, and exhaust gas purification can be promoted.

When the intake negative pressure in the intake pipe 4 decreases as the throttle valve 3 is forcibly opened, the valve body 61 is seated on the valve seat 60 due to the closing force of the air pressure sensing member 67, thereby closing the valve hole 53. Then, as the intake negative pressure in the output negative pressure chamber ₅₅₂ leaks to the atmosphere through the orifice 58, the throttle opener 57 allows the throttle valve 3 to close, and the intake negative pressure in the intake pipe 4 falls below a certain value. The above operation is repeated until the amount decreases.

When the vehicle speed decreases to less than 20 km/h, the vehicle speed detection switch 28 opens, so the solenoid valve 22 becomes de-energized, and the elastic force of the return spring 26 causes the valve body 25 to close the communication hole 20 and open the communication hole 21 at the same time. . Therefore, the pressure receiving chamber 55 of the throttle opener control valve 10
Although the intake negative pressure throttled by the orifice 30 is introduced into the throttle valve ₁ , since the throttle opener 57 is kept inactive as described above, the throttle valve 3 is allowed to close. On the other hand, since the communication hole 21 is open in the second pressure receiving chamber ₄₄₂ of the negative pressure operating valve 36, the maximum intake negative pressure cannot be maintained by the check valve 16, but as mentioned above, at a vehicle speed of less than 20 km/h, Since the generation of intake negative pressure does not decrease extremely, the valve element 45 of the negative pressure operated valve 36 does not sit on the first valve seat ₄₉₁ .

When the engine 1 stops, atmospheric pressure is introduced from the intake pipe 4 into the second pressure receiving chamber 44 ₂ of the negative pressure operating valve 36 as described in (a) above, so that the valve body 45 is released by the return spring 4 .
7 seats on the first valve seat 49 ₁ , the evaporated fuel storage function is performed, and atmospheric pressure is introduced into the pressure receiving chamber 55 ₁ of the throttle opener control valve 10 .

As described above, according to the present invention, the normally closed negative pressure operating valve 36 that opens when activated is provided in the evaporated fuel discharge path 50 that communicates the fuel reservoir such as the float chamber 32 with the intake system of the engine. In the middle of the negative pressure passage _P1 for introducing the intake negative pressure from the intake pipe 4 to the negative pressure responsive valve 36, there is a reverse valve that prevents the transmission of negative pressure from the negative pressure responsive valve 36 to the intake pipe 4 side. A stop valve 16 is interposed, and the negative pressure passage P ₁ is further provided with a bypass path P ₂ that bypasses the check valve 16, and a throttle opener control valve 10 is provided upstream of the check valve 16 in the negative pressure passage P _1. Connect the communication passages P ₃ to the side and connect them to the negative pressure passages.
P ₁ , the detour P ₂ and the communication path P ₃ are connected to each other by a first valve that connects the communication path P ₃ to the detour P ₂ and blocks the negative pressure path P ₁ from the upstream side of the check valve 16. A solenoid valve 22 is provided, which can take two positions: one position and a second position that communicates the communication passage P ₃ with the upstream side of the check valve 16 of the negative pressure passage P ₁ and blocks it from the bypass passage P ₂ ; teeth,
A vehicle speed switch 28 is connected which holds this in the first position when the vehicle speed is less than a predetermined value and in the _second position when the vehicle speed exceeds a predetermined value _. An orifice 30 is interposed between the upstream side of the stop valve 16 and the solenoid valve 22 to maintain constant communication between the two.
is held at the second position, so that the intake negative pressure can be smoothly transmitted to the throttle opener control valve 10, and therefore, if the intake negative pressure increases during engine deceleration, the throttle opener 57 can be activated immediately. On the other hand, when the vehicle is stopped or operating at low speed, that is, under operating conditions where it is not necessary to operate the throttle opener 5, the solenoid valve 22 is
Control valve 1 for throttle opener is held in position.
The throttle opener 57 can be held in an inoperative state by suppressing the transmission of the intake negative pressure to zero. Furthermore, when the vehicle is operating at low or high speeds, intake negative pressure is applied to the negative pressure operating valve 36 via the negative pressure passage _P1 to conduct the evaporated fuel discharge passage 50, and the evaporated fuel from the fuel reservoir 32 is transferred to the engine intake system. On the other hand, when the vehicle is stopped, the detour _P2 and the upstream side of the check valve ₁₆ of the negative pressure passage P1 are shut off by the solenoid valve 22 held in the first position. However, the intake negative pressure that had been maintained on the downstream side of the check valve 16, that is, on the negative pressure operating valve 36 side, is transferred to the orifice 3.
Since the fuel can be leaked to the intake pipe 4 side and thus to the atmosphere through the fuel vapor, the fuel vapor can be immediately closed to shut off the vaporized fuel discharge path 50, thereby preventing air pollution caused by the vaporized fuel.

In particular, the solenoid valve 22 has a first control function of controlling the supply of operating negative pressure to the throttle opener control valve 10 according to the vehicle speed, and a first control function of controlling the supply of operating negative pressure to the throttle opener control valve 10.
Since it also has a second control function that controls the supply of operating negative pressure to the opening/closing negative pressure operating valve 36 according to the vehicle speed, a common negative pressure passage P is provided for the two valves 10 and 36. Coupled with the fact that operating negative pressure can be introduced from ₁ , the structure of the device as a whole is simple, which can greatly contribute to cost reduction and improvement of assembly efficiency.

Further, when the solenoid valve 22 is in the first position, the orifice 30 connects the communication path P ₃ and the detour path P ₂ to the upstream side of the check valve 16 in the negative pressure path P ₁ through the orifice 30. In the communicating state, resistance can be provided to the transmission of negative pressure fluctuations in the intake pipe 4 to the control valve 10 and the negative pressure operating valve 36, and therefore, the throttle opener caused by the negative pressure fluctuations can be resisted. Malfunction of the control valve 10 and fluttering of the negative pressure operating valve 36 can be prevented.

[Brief explanation of the drawing]

The drawing is an explanatory diagram of an emission control system to which an embodiment of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 4... Intake pipe, 10... Throttle opener control valve, 16... Check valve, 22... Solenoid valve,
28... Vehicle speed switch, 30... Orifice, 32...
Float chamber as a fuel reservoir, 36... Negative pressure operated valve, 50
...Fuel vapor discharge path, 51...Air cleaner, P ₁ ...
Negative pressure passage, P ₂ … detour, P ₃ … communication passage.

Claims (1)

[Claims] 1. A normally closed negative pressure operating valve 36 that opens when activated is provided in the vaporized fuel discharge path 50 that communicates the fuel reservoir such as the float chamber 32 with the intake system of the engine, and the intake pipe is connected to the negative pressure operating valve 36. A check valve 16 for blocking the transmission of negative pressure from the negative pressure responsive valve 36 to the intake pipe 4 side is interposed in the middle of the negative pressure passage _P1 for introducing the intake negative pressure from the intake pipe 4, and The negative pressure passage _P1 includes a detour _P2 that bypasses the check valve 16, and a throttle opener control valve 10 that bypasses the check valve ₁ of the negative pressure passage P1.
6 Connect the communication passages P ₃ to communicate with the upstream side, and connect the negative pressure passage P ₁ , detour P ₂ and communication passage P ₃ to the upstream side.
There is a first position in which the communication path P ₃ is communicated with the detour path P ₂ and is blocked from the upstream side of the check valve 16 of the negative pressure path P ₁ , and a first position in which the communication path P ₃ is connected to the detour path P 2 and is blocked from the upstream side of the check valve 16 of the negative pressure path P 1 . A solenoid valve 22 is provided, which can take a second position that communicates with the upstream side of the check valve 16 of P ₁ and blocks it from the detour P ₂ ,
A vehicle speed switch 28 is connected to this electromagnetic valve 22, which maintains it in the first position when the vehicle speed is less than a predetermined value and in the second position when the vehicle speed exceeds a predetermined _value . This is an emission control device for an internal combustion engine for an automobile, in which an orifice 30 is interposed between the negative pressure passage _P1 and the upstream side of the check valve 16 to provide constant communication therebetween.