JPS597561Y2 - Carburetor fast idle release device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fast idle cam release device for regulating the throttle valve idle opening according to the degree of opening of the choke when the choke is activated in a carburetor equipped with an automatic choke such as an electric choke.

In order to stabilize the idle rotation of the internal combustion engine when it is started from a low temperature, a fast idle device is adopted in which a first idle cam is provided that works in conjunction with the choke valve, and this cam controls the throttle valve idle position to a slightly open side. .

This achieves stable idling operation at low temperatures.

By the way, in automatic chokes such as electric chokes that are commonly used these days, the driving source of the choke valve is bimetallic, so it is impossible to obtain enough force to release the engagement between the fast idle cam and the throttle valve.

Therefore, unless the driver operates the throttle valve, the throttle valve maintains the open position regulated by the fast idle cam even after complete warm-up.

As a result, the idle speed increases abnormally, which can cause overheating in vehicles equipped with catalytic converters.

In order to prevent this, conventionally the driver was required to operate the throttle valve to disengage it from the fast idle cam, depending on whether the engine had warmed up.

In view of this inconvenience, automatic fast idle release devices have recently been developed that open the throttle valve by detecting the temperature of the engine.

As such an automatic release device, for example, the
There is one described in No.-643.

In this device, a negative pressure port downstream of the throttle valve is connected via a pressure accumulation tank to a negative pressure actuation mechanism that controls engagement between the throttle lever and the fast idle cam.

The pressure accumulator tank is connected to an atmospheric shutoff valve that operates on a negative pressure operating mechanism.

Therefore, the pressure inside the accumulator tank is intermittently switched between atmospheric pressure and negative pressure, and as the choke valve opens, the throttle lever engages the lower step of the fast idle cam, gradually returning the throttle valve to its original idle position. I'm going to go.

However, in this conventional technology, since the negative pressure source is downstream of the throttle valve, an atmospheric open/close valve is required to switch the pressure storage tank between negative pressure and atmospheric pressure due to intermittent operation, which has the disadvantage of complicating the structure. .

The object of the present invention is to provide a new structure for canceling such fast idle operation, and the aim is to simplify the structure and reduce costs.

Hereinafter, the present invention will be specifically explained with reference to the drawings.
In the figure, reference numeral 1 denotes a carburetor body in which a venturi portion 3 is formed, a choke valve 5 is disposed upstream thereof, and a throttle valve 7 is disposed downstream thereof.

A valve shaft 5a of the choke valve 5 is rotatably attached to the main body 1.

In this embodiment, the choke valve 5 is of an electrothermal type and is connected to the link L.
This is connected to a spiral bimetal B, and a heater H made of nichrome wire or the like is arranged around it.

Therefore, when the heater heats up with the ON of the relay RL linked to engine starting, the bimetal B is gradually wound up, the link L is displaced to the right in the figure, and the choke valve 5 is thus allowed to open.

A first idle cam 8 is engaged with a pin 9 attached to the main body 1.

A lever 11 is also rotatably engaged with this pin 9, and is connected by a link 12 to another lever 13 fixed to the valve shaft 5a of the choke valve 5.

The protrusion 11a of the lever 11 and the first idle cam 8
A noleaf spring 14 is inserted between the recess 8' and the recess 8'.

Therefore, the lever 13 on the choke valve shaft 5a, the lever 11 on the first idle cam pin 9, and the first idle cam 8 move in conjunction with each other.

(The positional relationship among the cam 8, pin 9, and lever 11 will become clearer from the exploded view in FIG. 2.

) A throttle lever 15 is attached to the valve shaft 7a of the throttle valve 7.
is fixed in its center.

The throttle lever 15 is connected by its lower end 15b to an accelerator pedal link system (not shown), and its upper end 15a is connected to the link 1 of the fast idle cam 8.
It is provided facing stopper surfaces 8a, 8b, and 8C formed on the opposite side from 3.

The stopper surface is shaped like a step in order to shift the regulating position of the fast idle cam 8 to the closing side of the throttle valve 7 in response to the opening of the choke valve 5.

According to the present invention, the following structure is adopted in order to release the operation of the first idle cam 8 when the engine warms up after being left in idling operation.

That is, 17 is a negative pressure operating mechanism, and its operating rod 17
a is connected to the valve shaft 7 of the throttle valve 7 by the link 19.
It is connected to a lever 21 rotatably attached to a.

The lever 21 is provided with a protrusion 21 a that can engage with the lower end 15 b of the throttle lever 15 .

An operating negative pressure chamber 17b is formed on the side of a diaphragm (not shown) connected to the operating rod 21.

Therefore, by introducing the operating negative pressure into the negative pressure chamber 17b, the operating rod 17a is pulled, and the link 19 causes the lever 21, that is, the throttle valve 7, to rotate slightly in the counterclockwise direction, that is, in the opening direction.

According to the present invention, a pressure accumulating mechanism is provided for detecting the degree of warm-up of the engine as the time since its start and introducing the negative pressure for driving the throttle valve 7 into the negative pressure operating mechanism 17.

That is, this mechanism includes a pressure accumulation chamber 25, which is connected to the negative pressure passage 2.
7 communicates with the negative pressure chamber 17b.

The pressure accumulation chamber 25 is operated by an orifice 29, a one-way valve 31, a one-way delay mechanism, and a negative pressure passage 33.
It communicates with a negative pressure port 35 located downstream of the choke valve 5.

Next, the operation of the present invention will be described. Before starting, the port 35 is at atmospheric pressure, so the check valve 31 is opened and the pressure accumulation chamber 25 is opened.
is atmospheric pressure, and the operating rod 17a of the negative pressure operating mechanism 17 connects the protrusion 21a of the lever 21 to the other end 1 of the throttle lever 15.
5b.

In addition, since relay RL is OFF and heater H is not energized and is not heated, bimetal B displaces link L to the left in the figure, and as a result, choke valve 5 is in the fully closed position shown by the solid line. Take.

On the other hand, the upper edge 8'' of the first idle cam engages with the upper end 15a of the throttle lever, and as a result, the first idle cam is in a position rotated further counterclockwise (upward) than shown in the figure.

When the driver depresses the accelerator pedal and rotates the throttle valve 7 counterclockwise as shown by arrow P, the first eye cam 8 disengages from the throttle lever 15 and rotates clockwise (downward) under its own weight. Rotate to recess 8'
is engaged with spring 14, thereby stopping at the position shown in the figure.

When the throttle valve 7 is released, the upper end 15a of the throttle lever 15 assumes the position shown in the figure in which it abuts the uppermost engagement surface of the fast idle cam 8, completing preparations for choke operation.

When the engine is started, the idle position of the throttle valve 7 is on the most open side based on the fact that the throttle lever 15 is engaged with the uppermost stage 8a of the fast idle cam 8, so even if the engine is at a low temperature, The idle rotation becomes stable.

On the other hand, at the same time as the engine starts, relay RL is turned on and heater H is energized, so that bimetal B is gradually engulfed by the heat, link L moves to the right, and choke valve 5
is opened as shown in the imaginary line in the figure to weaken the choke effect.

The choke valve is allowed to open until the opening moment due to the eccentricity of the choke valve is balanced by the spring 14.

Immediately after this startup, negative pressure is generated in the port 35 and enters the pressure accumulation chamber 25, but the check valve 31 is closed this time.
Because of the orifice 29, the inflow of negative pressure into the chamber 25 is regulated,
Thus, the negative pressure level in the negative pressure chamber 17b is not sufficient to pull the actuating rod 19 as indicated by arrow Q at the beginning of startup.

When a period of time determined by the orifice 29 and the volume of the chamber 25 has passed since the start, the pressure in the pressure accumulation chamber 25 increases to a predetermined value, and the pressure in the negative pressure chamber 17b increases as the operating rod 17a moves toward the arrow Q.
It will be enough to pull it like this.

As a result, the protrusion 21a of the reher 21 causes the lower end 15b of the throttle lever 15 to rotate somewhat counterclockwise, and as a result, the upper end 15a does not separate from the fastening surface 8a of the first idle cam. Since there is an inherent biasing force to further open the choke valve 5, the first idle cam 8 rotates clockwise to some extent, and the upper end 15a of the throttle lever 15 engages with the lower step 8b of the first idle cam 8. do.

As a result, the idle opening degree of the throttle valve 7 is corrected to a smaller value, thereby preventing the idle speed from increasing as the engine warms up.

At the same time, the choke valve 5 is further opened, so the negative pressure in the negative pressure port 35 weakens, and as a result, the negative pressure operating mechanism 1
Similarly, the negative pressure in the negative pressure chamber 17b of No. 7 also pops out, and the engagement between the protrusion 21a and the lower end 15b of the throttle lever is released.

When the engine is further warmed up, the orifice 29 opens in the pressure accumulation chamber 25.
The negative pressure introduced through is sufficient to pull the actuating rod 17a of the negative pressure actuating mechanism 17 in the Q direction in the figure again, and the throttle lever tip 15a now engages with the lowest stage 8C, and the throttle valve The idle position of is further modified in the closing direction.

As described above, according to the present invention, the negative pressure at the downstream port of the choke valve is delayed by the pressure accumulating chamber 25 and
b to drive the actuating rod 17a and rotationally bias the slot lever, thereby sequentially correcting the engagement stage with the first idle cam 8 to the lower stage side.

Therefore, even if the engine is warmed up, the idle speed is prevented from increasing.

In FIG. 1, the port 35 is always located downstream of the choke valve 5, but the present invention is not limited thereto. The port 35' may be located downstream after opening.

However, when the throttle lever 15 is regulated by the high stage 8a of the first idle cam, it is natural that the choke valve 5 must be downstream of the maximum opening that can be opened by the bimetal B against the spring 14. .

In the present invention, the negative pressure port 35, which is a negative pressure source, is located downstream of the choke valve 5 but upstream of the throttle valve 7,
Through the parallel connection between the check valve 31 and the orifice 29,
It communicates with the pressure accumulation chamber 25.

Therefore, when the throttle lever 15 disengages from the fast idle cam 8 and the choke valve 5 opens due to the operation of the negative pressure operating mechanism, the negative pressure port 3
The pressure at No. 5 becomes atmospheric pressure, and the pressure at No. 25 in the accumulator chamber also becomes atmospheric pressure, and the operating rod 17a of the negative pressure operating mechanism returns to its original position, and then the pressure in No. 25 in the accumulator chamber returns to its original position. , the throttle valve 7 is held in that position.

Therefore, the operation of engaging the throttle lever with the gradually lower step portion of the fast idle cam can be realized without a complicated mechanism such as the conventional atmospheric opening/closing valve.

[Brief explanation of the drawing]

FIG. 1 is a fast idle release mechanism according to the present invention, and FIG. 2 is an exploded view of the fast idle cam mechanism in FIG. 1. 5...Choke valve, 7...Throttle valve, 8...First idle cam, 17...
... Negative pressure operation mechanism, 25 ... Pressure accumulation chamber, 29
... Orifice, 31 ... One-way valve,
35... Negative pressure port.

Claims (1)

[Scope of utility model registration request] A first idle cam that rotates in conjunction with an automatic choke valve is provided with a plurality of steps 8a-c, while a throttle valve 7
A first lever 21 and a second lever 15 are provided on the valve shaft of the throttle valve, the first lever is rotatable with respect to the valve shaft of the throttle valve, the second lever is fixed to the valve shaft of the throttle valve, The second lever 21 holds the throttle valve at an idle opening degree corresponding to the height by engaging with the stepped portion Ba-c, and the first lever 21 only moves in the direction of opening the throttle valve. It has a portion 21 a that engages with the lever 15 of No. 2,
In addition, the first lever is connected to the negative pressure operating mechanism 17, and the negative pressure chamber 17a of the negative pressure operating mechanism 17 is connected to the pressure accumulation chamber 25, and the pressure accumulation chamber is connected to the one-way valve 31 and the orifice 29. is connected to a negative pressure port 35 downstream of the choke valve 5 and upstream of the throttle valve 7 through a parallel connection of A first idle release device for a carburetor, characterized in that it is installed so that it opens when it is closed and when it is reversed.