JPH03185254A - First idle device - Google Patents

Abstract

PURPOSE:To enhance the starting and warm-up characteristics of an engine by providing a start cam and a warm-up cam for a first idle cam mechanism, opening a throttle valve as large as possible only at the start of the engine, and supplying only the required amount of mixture for maintaining rotation after the start of the engine. CONSTITUTION:A first idle cam 3, which is rotated by the rectilinear reciprocating action of a thermowax 1 which expands against a spring 2 during a temperature rise, comprises a start cam 3a and a warm-up cam 3b. A cam fluorolever 5 fixed to a throttle valve 4 is operated by the start cam 3a. A connecting lever 6 is provided coaxial with the first idle cam 3 and is linked through a wax lever 10 to a chalk lever 8 fixed to a chalk valve 7. Both cams 3a, 3b are held by a cam spring 11 in engagement with each other and an actuator 12 for forcibly disconnecting the start cam 3a from the throttle valve 4 after the start of the engine is connected to the start cam 3a.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fast idle device used in an internal combustion engine, and in particular, to obtain appropriate startability and warm-up characteristics over a wide range from extremely low temperatures to high temperatures. This article relates to a fast idle device and an auto-choke type carburetor.

[Conventional technology]

Conventionally, the auto choke mechanism installed in the carburetor of an internal combustion engine incorporates a fast idle device using a temperature-sensitive member that contracts and expands depending on the temperature of the engine coolant, and controls the opening of the choke valve and throttle valve. It's being adjusted.

An example of a conventional fast idle device will be explained based on FIG. 5. In the figure, reference numeral 1 denotes a thermowax which is a temperature sensing element, which expands when the temperature rises in response to the temperature of the engine cooling water, contracts when the temperature falls, and is returned to its original state by the spring force of the wax return spring 2. This wax return spring 2 is disposed coaxially with a fast idle cam 3 that replaces the linear reciprocating action of the thermowaxer with rotational motion. The fast idle cam 3 operates the force 11 fluoro lever 5 connected to the throttle valve 4 to set the first idle opening degree. A connect lever 6 is provided on the same axis as the fast idle cam 3, and this connect lever 6 engages and holds a choke lever 8 fixed to a choke valve 7 and a wax lever 10 incorporating a stranger spring 9.

In the conventional fast idle device configured as described above, the thermowax 1 is contracted by the wax return spring 2 at low temperatures, so the fast idle cam 3 rotates counterclockwise in the figure to open the throttle valve 4. Connect lever 6 also rotates in the same direction to close choke valve 7. When the temperature is increased, the operation is reverse to that described above.

[Problem to be solved by the invention]

However, with the above-mentioned conventional device, it is not possible to set both startability and warm-up characteristics to the best condition, and if the settings are made assuming no-acceleration starting, the number of idle rotations during warm-up will be low. The problem was that it was too expensive.

In other words, in order to improve starting performance, the fast idle cam 3 should be set so that the opening degree of the throttle valve 4 is large and the choke valve 7 is fully closed. Good starting performance is achieved over the entire range, even at high temperatures. However, with this setting, the warm-up rotation after starting becomes too high.

Therefore, in order to improve the warm-up characteristics, there is an example in which the stroke of the temperature sensing element is accelerated by heat transfer from a heat source other than cooling water, but this becomes complicated and expensive in terms of the system.

Furthermore, as described in Japanese Patent Application Laid-Open No. 52-106028, there is an example in which the fast idle cam is double-layered, but the engagement with the throttle valve is single-layer, and although it is effective for warming up characteristics, However, there is not much consideration given to startability.

An object of the present invention is to provide a fast idle device and an auto-choke type carburetor that have poor starting performance and warm-up characteristics.
It's about doing.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a fast idle device having a temperature sensing member and a fast idle cam mechanism that operates a throttle valve by expanding and contracting the temperature sensing member. Two cams for starting and warming up that rotate in response to the movement of the temperature sensing member.

A cam control means that operates the starting cam preferentially during startup to open the throttle valve to a constant opening, and after startup sets the idle opening of the throttle valve by the action of the warm-up cam. It is.

Preferably, the cam control device includes a cam spring that urges the starting cam and the warming-up cam in directions toward each other, and a cam spring that drives the starting cam against the cam spring after the starting and warms up the warming-up cam. and an actuator separate from the machine cam, the actuator preferably being a negative pressure actuator or a solenoid valve connected to the starting cam.

[Effect]

In the present invention configured in this manner, first, at the time of starting, the throttle valve is opened wide by the action of the starting cam to provide the best starting performance. After starting, if the starting cam remains as it is, the idle rotation will reach a high rotation, so the cam control means switches to the action of the warming-up cam.

If the cam control means is composed of a cam spring and an actuator, this is done by pulling the starting cam with the actuator, which releases the starting cam and activates the warm-up cam, so that the throttle valve is warmed up. By setting the desired idle opening and supplying only the amount of air-fuel mixture necessary to maintain rotation, it is possible to suppress warm-up rotation to a minimum.

When a negative pressure type actuator is used as the actuator, the negative pressure acts after the engine has completely exploded, so it is possible to maintain a reliable complete explosion state.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 denotes a thermowax which is a temperature sensing element, which expands when the temperature rises, contracts when the temperature falls, and is returned to its original state by the spring force of the wax return spring 2. Reference numeral 3 designates a fast idle cam that replaces the linear reciprocating action of the thermowax 1 with a one-rotation motion, and is composed of a starting cam 3a and a warm-up cam 3b. The wax return spring 2 is arranged coaxially with the warm-up cam 3b of the first idle cam 3. The starting cam 3a of the first idle cam 3 operates a cam follower lever 5 fixed to the throttle valve 4 to set the first idle opening degree. A connect lever 6 is provided on the same axis as the fast idle cam 3, and this connect lever 6 is connected to a choke lever 8 fixed to a choke valve 7 and a strangera.
A wax lever 10 incorporating a spring 9 is engaged and held.

The starting cam 3a and the warming-up cam 3b are engaged and held by a cam spring 11. A negative pressure actuator 12 is connected to the starting cam 3a.

This negative pressure actuator 12 is for forcibly releasing the connection between the starting cam 3a and the throttle valve 4 after the engine is started.

The torque of the cam spring 11 is set to be weaker than the return force of the throttle valve 4 and to a value that can be sufficiently pulled by the attractive force of the negative pressure actuator 12.

In addition, a pawl 13 is provided on the warm-up cam 3b to forcibly return the starting cam 3a to prevent the cam from running out of control even if the cam spring or the like breaks.

To explain the operation of this embodiment having the above configuration, first, when the temperature is low, the thermowax 1 contracts, the warming cam 3b rotates counterclockwise in the figure, and at the same time the connect lever 6 also rotates in the same direction, causing the choke Valve 7 is fully opened.

As the warm-up cam 3b rotates counterclockwise, the throttle valve 4
At this time, the starting cam 3a also rotates counterclockwise due to the force of the cam spring 11 and engages with the cam follower lever 5, but as mentioned above, the torque of the cam spring 11 is due to the return force of the throttle valve 4. Since the starting cam 3a cannot open the throttle valve 4, it stops in a state where it is lightly engaged with the cam fluoro lever 5. Therefore, the opening degree of the throttle valve 4 is set to the opening degree for warm air. However, at the time of starting, when the accelerator pedal is depressed by 1 [01M] to disengage the cam fluoro lever 5 and the starting cam, the starting cam 3a is moved by the force of the cam spring 1 to the warm-up cam 3.
b, and when the throttle valve 4 returns to the original device, the starting cam 3a is connected to the throttle valve 4 by engagement with the cam fluoro lever 5, and the throttle valve 4 cannot be opened widely. This allows for the best starting effect.

Note that when the temperature is around normal temperature, the displacement of the warm-up cam 3b is small, and the starting cam 3a does not rotate much even when the pedal is depressed. Therefore, the shape of the starting cam 3a is such that a constant velocity cam is used in order to maintain the same opening degree of the throttle valve 4 regardless of the temperature at the time of starting, so that the starting opening degree is guaranteed even with a slight movement.

After starting the engine, if the starting cam 3a remains engaged with the cam fluororeper 5, the rotation will reach high speed. Therefore, by pulling the starting cam 3a with the negative pressure actuator 12, the engagement is forcibly released and the throttle is stopped. Disconnect from valve 4. As a result, the cam fluoro lever 5 connects with the throttle valve 4 by engaging with the warm-air cam 3b, sets the opening of the throttle valve 4 to the warm-air opening, and only controls the amount of air-fuel mixture necessary to maintain rotation. supply This makes it possible to minimize warm-up rotation.

Note that when the negative pressure actuator 12 pulls the starting cam 3a, a load is applied to the negative pressure actuator 12 by the sum of the torque from the cam spring 11 and the frictional resistance between the starting cam 3a and the cam follower 5, but the load is not very large. Since the load is not large, the ones commonly used in automobiles can be used as is.

In addition, since the negative pressure actuator operates after the two engines have completely exploded, it is possible to maintain a reliable complete explosion.6 As stated above, in this example, starting and warm-up are individually considered, and the best starting time is determined. This is so that both the engine speed and the warm-up rotation speed can be obtained.

Figure 3 shows the relationship between water temperature ("C) and throttle valve opening (deg) in the conventional example and this embodiment. In the figure, the solid line is for the conventional example, and the broken line is for the warm-up state in this embodiment. ,
− point Jl [is also at the time of starting the present embodiment.

Figure 4 shows the engine rotational speed (rp
FIG. 2 is a diagram showing the relationship between warm-up elapsed time (minutes) and warm-up elapsed time (minutes); in the diagram, the solid line is for Kino in the conventional example, and the broken line is for this embodiment.

As is clear from these FIGS. 3 and 4, this example significantly improved both startability and warm-up characteristics compared to the conventional example.

The present invention can be applied not only to a carburetor but also to an SPI throttle chamber using a fast idle device.

Further, the actuator for releasing the connection between the starting cam and the throttle valve 4 is not limited to a negative pressure actuator, and for example, a solenoid valve may be used.

〔Effect of the invention〕

According to the present invention, a starting cam and a warm-up cam are provided as a fast idle cam mechanism, and the throttle valve is opened as wide as possible only during starting, and after starting the engine, only the amount of air-fuel mixture necessary to maintain rotation is supplied. This has the effect of improving both startability and warm-up characteristics.

Further, according to the present invention, in order to suppress warm air rotation as much as possible,
It eliminates unnecessary fuel flow and has a significant effect on fuel consumption, especially in winter in cars that use a carburetor.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional front view of a fast idle device according to an embodiment of the present invention, Fig. 2 is a side view of the embodiment shown in the construction drawing, and Fig. 3 is a conventional example and a fast idle device according to this embodiment. FIG. 4 is a diagram showing the relationship between water temperature and throttle valve opening in the warm-up characteristic; FIG. 4 is a diagram showing the relationship between engine speed and elapsed warm-up time in the conventional example and this embodiment; FIG. 2 is a cross-sectional front view showing an example of an idle device. DESCRIPTION OF SYMBOLS 1... Temperature sensing element, 3a... Starting cam, 3b... Warming cam, 4... Throttle valve, 12... Negative pressure type actuator (actuator).

Claims (1)

[Scope of Claims] 1. In a fast idle device having a temperature sensing member and a fast idle cam mechanism that operates a throttle valve by expansion and contraction of the temperature sensing member, the first idle cam mechanism is configured to Two cams for starting and warming up rotate in response to movement, and at the time of starting, the starting cam is activated preferentially to open the throttle valve to a constant opening,
A fast idle device comprising: a cam control means for setting the idle opening degree of the throttle valve by the action of the warm-up cam after startup. 2. The fast idle device according to claim 1,
The cam control device includes a cam spring that urges the starting cam and the warming-up cam toward each other, and a cam spring that drives the starting cam against the cam spring after starting, and the warming-up cam that drives the starting cam against the cam spring after starting. A fast idle device comprising: an actuator that is separated from the first idle device; 3. The fast idle device according to claim 1,
A fast idle device, wherein the actuator is a negative pressure actuator or a solenoid valve connected to a starting cam. 4. An auto-choke type carburetor, characterized in that it is provided with the fast idle device according to claim 1.