JPH0238040Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a throttle valve control device for a carburetor, and in particular, it is controlled by negative pressure in the intake passage to reduce hydrocarbons (HC), which are harmful components of exhaust gas during deceleration. The present invention relates to a throttle valve control device for a carburetor which is capable of fully performing its function without hindering the return of the throttle valve to an idle opening position even if the negative pressure for controlling operation is set weakly.

[Prior Art] In an internal combustion engine that rotates at high speed, when the throttle valve is suddenly closed, the filling ratio in the cylinder decreases, the air-fuel mixture becomes rich, the combustion efficiency decreases, and the amount of hydrocarbons (HC) is reduced. This has the disadvantage of increasing emissions.
Therefore, in the past, the throttle valve was controlled by the negative pressure in the intake passage on the downstream side of the valve, and the throttle valve was temporarily stopped at a predetermined opening position (positioner opening position) that was slightly opened from the idle opening position, and then the throttle valve was moved to the idle opening position after a while. A so-called throttle positioner is used to reduce the generation of unburned gas by returning the engine to

[Problems to be solved by the invention] However, if the negative pressure for controlling the throttle positioner is set weakly so that it can function satisfactorily in a wide range of operating conditions, the throttle may be throttled due to the weak negative pressure in the intake passage that occurs under certain operating conditions. This may cause an inconvenience in that the valve cannot return to the idle opening position. For example, in connection with high-speed operation with the transmission in the neutral position under no load (so-called racing operation) or gear change operation with a reduced load, the throttle valve is temporarily closed in such operating conditions and the negative pressure is slightly reduced. Get stronger. Therefore, if the negative pressure for controlling the throttle positioner is set weakly, the throttle valve cannot return to the idle opening position, causing the problem that the engine rotation increases.

[Purpose of the invention] Therefore, the purpose of this invention was to control hydrocarbons (HC), which are harmful components of exhaust gas during deceleration, by controlling the negative pressure in the intake passage.
In a device that aims to reduce the amount of hydrocarbons (HC) emitted under a wide range of operating conditions, it is possible to set a weak negative pressure for controlling the throttle valve without inhibiting its return to the idle opening position. The object of the present invention is to realize a throttle valve control device for a carburetor that can function satisfactorily.

[Means for solving the problem] In order to achieve this object, this invention provides an actuator for controlling the throttle valve closing operation of the carburetor, and also connects the actuator passage communicating with the diaphragm chamber of this actuator to a branch point. The first passage is branched to form a first passage and a second passage, and the first passage is sequentially provided with a first delay mechanism and a control valve that disconnects the first passage from communicating with the atmosphere from the side closer to the branching point. At the same time, the negative pressure in the intake pipe becomes weaker than a predetermined pressure, so that a negative pressure passage that controls the control valve is opened to the intake passage downstream of the throttle valve in order to communicate the first passage with the atmosphere, and the second passage is opened to the intake passage downstream of the throttle valve. There is a second
A delay mechanism is provided at a branch point of the actuator passage, and the communication between the actuator passage and the first passage is cut off in at least one of the operating states of the transmission neutral position and the clutch disengagement, and the communication between the actuator passage and the second passage is interrupted. It is characterized in that it is provided with a switching valve that performs switching operation to establish communication with the passage.

[Function] According to this invention, during deceleration, which is an operating state in which the throttle valve closes suddenly, the switching valve communicates the actuator passage with the first passage, communicates the intake passage downstream of the throttle valve, and connects the actuator passage with the intake passage on the downstream side of the throttle valve. The communication between the first passage and the atmosphere is cut off due to strong negative pressure acting on the control valve that converts the downstream intake ventilation negative pressure into a negative pressure for controlling operation, and then when the negative pressure becomes weaker than a predetermined pressure, the first passage is closed. One passage communicates with the atmosphere. This causes the actuator to function as a throttle positioner.

In addition, in connection with driving operations such as a so-called racing operation in the neutral position of the transmission when there is no load or a gear shifting operation in which the load is reduced, in such operating conditions, the switching valve connects the actuator passage to the second passage communicating with the atmosphere. The actuator functions as a doss pot.

[Example] Next, an example of this invention will be described in detail based on the drawings. The figure shows an embodiment of this invention, where 2 is an intake passage, 4 is a throttle valve, and 6 is an actuator.
The actuator 6 has a diaphragm chamber 10 defined by a diaphragm 8 . The diaphragm 8 is provided with a rod 12.
2 is brought into contact with a lever 14 for opening and closing the throttle valve in order to hold the throttle valve 4 at a predetermined opening position (positioner opening position). Further, a spring 16 that presses the diaphragm 8 is installed inside the diaphragm chamber 10. The elastic force of this spring 16 is set to be weaker than the elastic force of the return spring 18 that closes the throttle valve 4.

An actuator passage 20 communicating with the diaphragm chamber 10 of the actuator 6 is branched at a branch point 22 to form a first passage 24 and a second passage 26. The first passage 24 is provided with a first throttle 28, which is a first delay mechanism, and a control valve 30, which connects and cuts off the first passage 24 from the atmosphere, sequentially from the side closer to the branch point 22. The control valve 30 has an atmospheric chamber 32 that communicates with the first passage 24 on one side and opens the other side to the atmosphere.
and a negative pressure chamber 36 defined by the atmospheric chamber 32 and a diaphragm 34. The diaphragm 34 is provided with a valve body 38 that communicates with and shuts off the atmospheric chamber 32 and the first passage 24 .
8 is biased in the opening direction by a spring 40. Negative pressure passage 4 communicating with the negative pressure chamber 36
2 opens into the intake passage 2 on the downstream side of the throttle valve.
As a result, the first passage 24, in which a negative pressure stronger than the negative pressure set by the elastic force of the spring 40 acts on the negative pressure chamber 36, is cut off from communicating with the atmosphere, and a weak negative pressure is applied to the negative pressure chamber 36. When activated, the spring 40 communicates the first passageway 24 with the atmosphere.

A second passage 26 formed by branching the actuator passage 20 at a branch point 22 is provided with a second throttle 44, which is a second delay mechanism, and is opened to the atmosphere.

An electrical switching valve 46 is provided at the branch point 22 of the actuator passage 20, and allows the actuator passage 20, the first and second passages 24, 26 to communicate with a valve chamber 48. This valve chamber 48 has a valve body 5.
0 is installed internally and actuated by a spring 52 and a solenoid 54 to connect the actuator passage 20 to the first passage 2.
4 and the second passage 26 selectively.

The switching valve 46 switches between the actuator passage 20 and the first passage 24 under at least one of the following operating conditions: when the transmission (not shown) is in a neutral position and when the clutch (not shown) is disengaged. The actuator passage 20 and the second passage 26 are switched to communicate with each other. Therefore, the main switch 58 that turns on and off the power to the battery 56
Clutch switch 6 detects clutch disengagement.
0 and a neutral position switch 62 that detects the neutral position of the transmission are connected in sequence, and this neutral position switch 6
2 is connected to the switching valve 46. As a result, the switching valve 46 is operated to communicate the actuator passage 20 with the second passage 26 depending on the operating state of the clutch being disengaged or the transmission being in the neutral position.

Next, the action will be explained.

When the clutch is engaged and the transmission is in an engaged position other than the neutral position, the switching valve 46 communicates the actuator passage 20 with the first passage 24. At this time, when deceleration is performed, the throttle valve 4 returns against the spring 16 by the spring 18, and the rod 12
Close quickly while pushing back. This prevents the air in the diaphragm chamber 10 from flowing out into the atmosphere from the atmospheric chamber 32 through the actuator passage 20, the valve chamber 48, the first passage 24, and the first throttle 28. However, if the negative pressure in the intake passage due to sudden closing of the throttle valve 4 is stronger than the negative pressure set by the spring 40 of the control valve 20 for controlling operation, the valve body 38 closes the space between the atmospheric chamber 32 and the first passage 24. do. Therefore, air cannot flow out from the diaphragm chamber 10, and the lever 14 of the throttle valve 4 comes into contact with the rod 12, so that the throttle valve 4 is held at a predetermined opening position (positioner opening position). Thereby, it is possible to avoid the inconvenience of the intake passage negative pressure becoming abnormally strong. Then,
When the negative pressure in the intake passage due to deceleration becomes weaker than the negative pressure that causes the control valve 30 to operate, the valve body 38 communicates between the atmospheric chamber 32 and the first passage 24 . As a result, the air in the diaphragm chamber 10 of the actuator 6 is discharged to the atmosphere, but the first throttle 28 restricts the discharge. Therefore, the throttle valve 4 gradually returns to the idle opening position while pushing back the rod 12 by the return spring 18. Thus, when the clutch is engaged and the transmission is in an engaged position other than the neutral position, the actuator passage 20 and the first
The actuator 6 is communicated with the passage 24 to function as a throttle positioner, thereby suppressing an increase in hydrocarbons (HC) caused by sudden closing of the throttle valve during deceleration.

If the negative pressure for controlling the control valve 30 is set weakly, the valve body 38 of the control valve 30 will close, causing problems such as the throttle valve 4 not being able to return to the idle opening position. Examples of operating conditions that generate such negative pressure include high-speed operating operations with the transmission in the neutral position under no load (so-called racing operations) and operating conditions during gear shifting operations where the load is reduced. Under normal operating conditions, the throttle valve is temporarily closed and the negative pressure increases slightly. Therefore, the switching valve 46 is operated to communicate the actuator passage 20 of the actuator 6 with the second passage 26 so that the return of the throttle valve 4 is not inhibited by the negative pressure in such an operating state. That is, when the transmission is in the neutral position or the clutch is disengaged in connection with a gear shifting operation, the switching valve 46 is opened by the operation of the clutch switch 60 or the neutral position switch 62.
is switched. Thereby, the valve body 50 of the switching valve 46 is connected to the actuator passage 20 and the first passage 24.
A second passage 26 that cuts off communication with the air and communicates with the atmosphere.
communicate with. Therefore, the air in the diaphragm chamber 10 is restricted from flowing out by the second throttle 44, and the throttle valve 4 gradually returns to the idle opening position while pushing back the rod 12. Therefore, even if the negative pressure for controlling the control valve 30 is set weakly, the actuator 6 is caused to function as a dart pot by the second throttle 44 during driving operations such as racing operations under no load or gear shifting operations when the load is reduced. It is possible to gradually return the throttle valve 4 to the idle opening position without hindering the return, thereby reducing hydrocarbons (HC) and avoiding the inconvenience of increased engine rotation.

In this embodiment, a throttle is used as an example of the delay mechanism, but a delay valve consisting of a throttle and a check valve may also be used.

[Effects of the invention] As described above, according to this invention, during deceleration, which is an operating state in which the throttle valve closes suddenly, the actuator passage and the first passage are communicated with each other by the switching valve, and the negative pressure in the intake passage on the downstream side of the throttle valve is reduced. Communication between the first passage and the atmosphere is cut off by a control valve that controls the negative pressure, and then when the negative pressure becomes weaker than a predetermined pressure, the first passage is communicated with the atmosphere. This allows the actuator to function as a throttle positioner and reduces hydrocarbons (HC) during deceleration. In addition, even if the negative pressure for controlling the control valve is set weakly, such negative pressure may be caused by operations that generate such negative pressure, such as a so-called racing operation in the neutral position of the transmission when no load is applied, or a gear change operation to disengage the clutch when the load decreases. In connection with driving operations, in such operating conditions, the switching valve separates the actuator passage from the second
The actuator is communicated with the passage to function as a dart pot. Thereby, the throttle valve can be gradually returned to the idle opening position without being hindered, hydrocarbons (HC) can be reduced, and the problem of increased engine rotation can be avoided.

In this way, even if the negative pressure for controlling the control valve is set weakly, the function can be sufficiently performed in a wide range of operating conditions, and hydrocarbons (HC) can be reduced.

[Brief explanation of the drawing]

The figure is a schematic explanatory diagram showing an embodiment of the device of this invention. In the figure, 4 is a throttle valve, 6 is an actuator, 20 is an actuator passage, 24 is a first passage, 26 is a second passage, 28 is a first throttle, 30 is a control valve, 42 is a negative pressure passage, and 44 is a second passage. 46 is a switching valve, 60 is a clutch switch, and 62 is a neutral position switch.

Claims (1)

[Scope of utility model registration request] An actuator for controlling the closing operation of the throttle valve of the carburetor is provided, and an actuator passage communicating with the diaphragm chamber of the actuator is branched at a branch point to form a first passage and a second passage, and the first passage includes a A first delay mechanism and a control valve for communicating and shutting off the first passage to the atmosphere are provided in order from the side closest to the branch point, and the negative pressure in the intake pipe is weakened below a predetermined pressure, thereby opening the first passage to the atmosphere. A negative pressure passage for controlling the control valve is opened to the intake passage downstream of the throttle valve, a second delay mechanism is provided in the second passage, and a transmission neutral position is provided at a branch point of the actuator passage. The present invention is characterized by providing a switching valve that operates to cut off communication between the actuator passage and the first passage and to make communication between the actuator passage and the second passage in accordance with at least one of the operating conditions of and clutch disengagement. A throttle valve control device for a carburetor.