JPH0734210Y2 - Engine start control mechanism - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention uses a warm-up air control device capable of obtaining an optimum first idle air amount during warm-up operation.
The present invention relates to an engine start control mechanism that improves startability when the engine restarts at a high temperature.

[Conventional technology]

As an example of the above-mentioned warm air control device, there is one proposed by the present applicant in Japanese Patent Application No. 62-326194.

This device will be described with reference to FIG. 4. A throttle valve 2 is provided in an intake passage 1 of an intake cylinder, and the throttle valve 2 is bypassed to allow the intake passage 1 to be located upstream (upstream of the venturi) and downstream thereof. Is provided with a main bypass air passage 3, and a sub bypass air passage 5 branched upstream of the main throttle 4 of the passage 3 joins the main bypass air passage 3 immediately before the outlet, and from the main throttle 4. A sub diaphragm 6 having a small diameter is provided. A second chamber 9 partitioned by the diaphragm 7 from the first chamber 8 of the main bypass air passage 3 is formed on the downstream side of the sub-throttle 6 of the sub-bypass air passage 5, and is connected to the diaphragm 7 and connected to the main bypass air passage. Three
The valve 10 that opens and closes the valve is elastically pressed by a spring 11 in a direction that closes the main bypass air passage 3. A needle valve 12 that can open and close the seat portion 5a of the sub bypass air passage 5 by advancing and retreating is disposed on the downstream side of the second chamber 9, and a spring 13 is connected to the rear end of the needle valve 12.
Further, a bimetal 14 that is displaced so as to rotate rightward as the temperature of the cooling water of the engine rises is pressed against the tip.

Therefore, when the cooling water temperature of the engine is low, the air flow rate Qa ₁ of the sub bypass air passage 5 is relatively large because the flow passage cross-sectional area between the needle valve 12 and the seat portion 5a is large, and the negative pressure P ₂ of the second chamber 9 is small. Is also large, the valve opening amount of the valve 10 is increased against the elasticity of the spring 11, and the air flow rate Qa ₂ of the main bypass air passage 3 is increased. Further, when the cooling water temperature is high, the bimetal 14 is displaced clockwise, so the needle valve 12
And the flow path cross-sectional area between the seat part 5a and the air flow rate Qa
₁ , the negative pressure P ₂ becomes smaller, and the air flow rate Qa ₂ also decreases.

By the way, the air flow rate Qa ₁ passing through the sub-throttle 6 is However, B ... flow passage cross-sectional area of the sub-throttle 6, Ka ... flow passage coefficient, P ₁ ... Throttle valve upstream pressure, and the air flow rate Qa ₂ passing through the main throttle 4 is However, it is determined by A ... Flow passage cross-sectional area of the main throttle 4, α ... Load per unit area of the spring 11 applied to the diaphragm 7.

Therefore, by the small air flow rate Qa ₁ passing through the sub throttle 6,
The large air flow rate Qa ₂ passing through the main throttle 4 can be controlled.

Further, when the engine is stopped, the valve 10 closes the main bypass air passage 3 by the elasticity of the spring 11.

[Problems to be solved by the device]

By the way, although the cooling water temperature becomes high due to the operation of the engine, when restarting in a high temperature state when the engine is stopped,
Especially when the outside temperature is high, the engine room becomes very hot and the manifold is filled with gasoline vapor, which causes the mixture to be too rich during cranking, and the engine speed is low. There was a problem that the scavenging of gasoline vapor was not carried out promptly and the startability of the engine was poor.

Also, at low temperature start, cranking is performed at the idle opening, and the engine speed does not rise sufficiently because the engine friction is large, so the intake air flow rate is small and the fuel atomization is bad. There was the problem of poor startability.

The present invention has been made in view of the above problems, and an object thereof is to provide a start control mechanism for an engine, which uses a warm air control device to improve startability during high temperature restart and low temperature start of the engine.

[Means for Solving the Problems]

The engine start control mechanism according to the present invention includes a main bypass valve and a sub bypass air passage, which bypass the throttle valve and is provided with a main throttle and a sub throttle, respectively. Engine equipped with a warm air control device that controls the opening of a valve that is connected to a diaphragm that divides both passages and that can open and close the main bypass air passage, and that supplies an air flow rate according to the warm air state. In the above, the elastic member is provided in the valve or the main bypass air passage so as to have an elasticity such that the valve is opened small at the time of engine start and cranking and closed at the time of complete explosion of the engine.

[Action]

Therefore, when restarting the engine at a high temperature, when starting the engine and cranking, air flows in through a small gap between the valve and the seat to scavenge the gasoline vapor filling the manifold, and at the same time, to mix the air-fuel mixture with the proper air-fuel ratio. Is created to accelerate the start of the engine, the valve is closed against the elastic force of the elastic member due to the complete explosion of the engine, and then normal operation is performed. The ranking becomes lighter, the engine speed rises, and the air flow required for starting is supplied,
The required manifold negative pressure is secured.

〔Example〕

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 3, but the same parts as those of the above-described prior art will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 and FIG. 2 are cross-sectional views of main parts showing the main bypass air passage 3 and the valve 10 of the warm-up air control device. The first chamber 8 is provided in the main bypass air passage 3 on the upstream side of the valve 10.
Is configured. In the figure, 16 is a substantially three-pronged leaf spring that is connected to the valve 10. When the engine is stopped, started, and cranked, the tips of the leaf springs contact the wall surface,
Against the elasticity of 11, the seat part 3a of the passage 3 and this seat part
A gap C having a slight width 1 is formed between the contact portion 10a of the valve 10 which can be seated on the seat 3a, and the seat portion 3a is seated on the seat portion 3a by the negative pressure of the manifold when the engine is completely detonated. It has elasticity enough to close the passage 3 (see FIG. 2).

Since the present embodiment is configured as described above, if the engine is restarted in a high temperature state immediately after the engine is stopped, the manifold will be filled with gasoline vapor and a negative pressure will be generated in the manifold due to cranking. Therefore, the clearance C between the valve 10 and the seat portion 3a in the warm-up air control device
Air flows through the main bypass air passage 3 to the manifold, so that the gasoline vapor in the manifold is scavenged through the cylinder, and at the same time, a portion of the mixture has an appropriate air-fuel ratio that is suitable for starting the engine. Therefore,
The start-up is accelerated and the complete explosion of the engine is performed quickly.

The complete explosion increases the manifold negative pressure and the downstream negative pressure of the valve 10, so that the valve 10 moves to the left against the elastic force of the leaf spring 16 and closes the main bypass air passage 3. After that, the flow passage cross-sectional area between the needle valve 12 and the seat portion 5a is determined according to the temperature of the engine cooling water without being affected by the elasticity of the leaf spring 16, and the air flow rate Qa ₁ of the sub bypass air passage 5 is determined. Is determined, the valve opening amount of the valve 10 and the air flow rate Qa ₂ of the main bypass air passage 3 are determined, and the additional air flow rate (Qa ₁ , Qa ₂ ) according to the warmed-up state is controlled.

Further, at the time of low temperature start, the air flow from the clearance C flows into the cylinder, so that the cranking of the engine becomes lighter, the engine speed increases, the air flow rate necessary for the start is supplied, and the atomization of fuel is also improved. Therefore, the startability is improved.

Since the manifold negative pressure becomes 400 mmHg or more after the engine complete explosion, the elasticity of the leaf spring 16 should be set so that the valve 10 closes the main bypass air passage 3 when the downstream pressure of the valve 10 is about 250 mmHg. Good.

Also, the clearance C between the valve 10 and the seat portion 3a when the engine is stopped
If the opening area of is too large, the manifold negative pressure (50 mmHg or more) required during cranking cannot be secured due to the large air density when starting at low temperature (especially extremely low temperature of 0 ° C or less). . Therefore, in order to limit the air flow rate from this gap C during cranking, it is necessary to make the width 1 small to some extent.
By determining the shape of, the manifold negative pressure required to operate each actuator such as the valve 10 during cranking at low temperature is ensured, and the engine startability at high temperature restart and low temperature start is improved. It is possible to secure the air flow rate required for goodness.

For example, in an engine with a displacement of 1.3 to 1.5 liters, it is preferable that the area of the gap C is the same as the area of a circle corresponding to φ4 to φ6 cm. Therefore, the seat diameter of the seat portion 3a of the main bypass air passage 3 is φ10 cm. If there is, the width l of the gap C is 0.4
It should be ~ 0.6 cm.

As described above, according to this embodiment, it is possible to improve the startability when the engine is restarted at a high temperature and when the engine is restarted at a low temperature. In addition, at the time of cold start, it is possible to secure the manifold negative pressure required to operate each actuator during cranking.

Although the leaf spring 16 is fixed to the valve 10 in the present embodiment, the leaf spring 16 is fixed to the main bypass air passage 3 so that the tip portion of the leaf spring 16 presses the valve 10 to form the gap C at the engine start and cranking. May be.

[Effect of device]

As described above, according to the engine start control mechanism of the present invention, the valve that opens and closes the main bypass air passage of the warm air control device is opened small at the time of engine start and cranking, and at the time of complete explosion. Since the elastic member having elasticity enough to close the valve is provided, it is possible to improve the startability during high temperature restart and low temperature restart. Further, at the time of low temperature starting, it is possible to secure the manifold negative pressure necessary for cranking.

[Brief description of drawings]

1 and 2 show an embodiment of a starting control mechanism according to the present invention, which is a cross-sectional view of a main part showing a valve open state and a valve closed state, respectively, and FIG. 3 is a plane view of a leaf spring. Figure, 4th
The figure is a schematic cross-sectional view of a warm-up air control device. 2 ... Throttle valve, 3 ... Main bypass air passage,
4 ... Main throttle, 5 ... Sub bypass air passage, 6 ... Sub throttle, 7 ... Diaphragm, 10 ... Valve, 16 ... Leaf spring.

Claims (1)

[Scope of utility model registration request] 1. A valve for controlling opening and closing of a main bypass air passage by providing a main throttle and a sub-throttle, respectively, in a main bypass air passage and a sub bypass air passage that bypass the throttle valve and communicate with the intake passage on the upstream side and the downstream side, respectively. The main and sub bypass air passages are partitioned by the diaphragm connected to
In an engine equipped with a warm air control device that controls the opening of the valve according to the air flow rate of the sub-bypass air passage whose opening is controlled according to the cooling water temperature of the engine, A starting control mechanism comprising an elastic member provided in the valve or the main bypass air passage, the elastic member having such an elasticity that the valve is opened small during cranking and closed when the engine is completely detonated.