JPH10169510A - Start control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an air inflow or an LPG outflow, when an engine is started, into the primary decompression chamber of a vaporizer which makes a closed space during the engine stop, and improve startability in the engine using LPG as fuel. SOLUTION: When an ignition switch is turned ON, only an LPG solenoid valve is turned ON to be kept in an ON condition during a set time T, while keeping a vacuum locking solenoid valve and a slow-cut solenoid valve in an OFF condition regardless of cranking. This can prevent a fuel rarefied condition due to the backflow of air into the primary decompression chamber of a vaporizer, or a fuel excess thick condition due to an LPG outflow from a slow system; and can sufficiently fill the primary decompression chamber with LPG to supply LPG fuel having set pressure to an engine, thereby improving startability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine start control device for improving startability when starting an engine using LPG as fuel.

[0002]

2. Description of the Related Art In general, in a fuel supply system of an engine using LPG as fuel, LPG from a cylinder storing LPG is decompressed and regulated by a vaporizer and supplied to an LPG mixer provided in an intake passage of the engine. A two-stage decompression type vaporizer having a primary decompression chamber and a secondary decompression chamber is often used as a vaporizer.
Solenoid valves are interposed in the passage connecting the G cylinder and the primary decompression chamber of the vaporizer and the slow passage connecting the primary decompression chamber of the vaporizer and the LPG mixer, respectively. A passage connecting to the primary pressure reducing chamber is made conductive to secure starting fuel, and a slow passage is made conductive to secure fuel for slowing.

[0003] For example, Japanese Utility Model Laid-Open Publication No. Hei 2-13064 discloses that a solenoid valve in a passage connecting an LPG cylinder and a primary decompression chamber of a vaporizer and a solenoid valve in a slow passage are both provided before cranking at the time of engine start. A technique has been disclosed in which, by performing an opening operation, starting fuel is supplied from an LPG cylinder before cranking regardless of the level of intake pipe negative pressure generated during cranking, thereby improving startability.

[0004]

When the engine using LPG as fuel is stopped, the solenoid valve between the LPG cylinder and the vaporizer is closed during operation of the engine to protect the vaporizer. LPG in the path is exhausted and stalls, but immediately after the engine stops, the solenoid valve in the passage from the vaporizer to the LPG cylinder, the solenoid valve in the slow passage, and the secondary valve in the secondary decompression chamber are all closed. The primary decompression chamber of the vaporizer is one closed space of about atmospheric pressure. Since the vaporizer is usually preheated by the engine cooling water to promote the vaporization of LPG, it is in a high temperature state immediately after the engine is stopped. The remaining LPG contracts and the primary decompression chamber becomes negative pressure.

Therefore, if the time until cranking after turning on the ignition switch for starting the engine is short, the primary decompression chamber of the vaporizer is sufficiently LPG.
Before being filled with air, the air flows back into the primary decompression chamber through the slow passage to become a fuel-lean state, and conversely, if the time until cranking is long, from the primary decompression chamber of the vaporizer through the slow passage There is a problem that LPG flows out to the LPG mixer and the fuel becomes too rich, which may lead to failure in starting and malfunction of the engine.

Further, the secondary valve of the secondary pressure reducing chamber is forcibly closed (vacuum lock) when the engine is stopped, in which no negative pressure of the intake pipe is generated, and the vacuum lock is provided by the negative pressure of the intake pipe when the engine is started. In many cases, there is a vacuum lock mechanism that cancels the pressure.If cranking is performed to start the engine in a state where the primary decompression chamber of the vaporizer is at a negative pressure, the vacuum lock is released due to the generation of the intake pipe negative pressure, and the secondary decompression chamber is released. , The secondary valve is opened, and air flows backward from the secondary decompression chamber to the primary decompression chamber, similarly causing the startability to deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. For an engine using LPG as a fuel, air inflow into the primary decompression chamber of a vaporizer, which is one closed space when the engine is stopped, when the engine is started. It is an object of the present invention to provide an engine start control device capable of preventing start-up and LPG outflow and improving startability.

[0008]

According to the first aspect of the present invention,
A first solenoid valve for conducting and blocking a passage connecting the cylinder for storing LPG and the primary decompression chamber of the vaporizer; and a second solenoid valve for conducting and blocking a slow passage communicating from the primary decompression chamber of the vaporizer to the LPG mixer. And a start control means for maintaining the second solenoid valve in a closed state and opening the first solenoid valve for a set time at the time of engine start regardless of the presence or absence of cranking. It is characterized by the following.

According to a second aspect of the present invention, a first valve for conducting and blocking a passage connecting a cylinder for storing LPG and a primary decompression chamber of a vaporizer, and a communication from the primary decompression chamber of the vaporizer to the LPG mixer. A second valve for conducting and shutting off a slow passage, and a third valve for conducting and shutting off a passage connecting a vacuum lock chamber of the above-mentioned burr-parallel and an intake pipe of the engine. Regardless of the above, a start control means is provided for opening the LPG solenoid valve for a set time while maintaining the second solenoid valve and the third valve in the closed state.

In other words, according to the first aspect of the present invention, when the engine is started, regardless of the presence or absence of cranking, the cylinder and the vaporizer that store the LPG by blocking the slow passage communicating from the primary pressure reducing chamber of the vaporizer to the LPG mixer. The passage connecting the primary decompression chamber is made conductive for a set time,
Fully fill the primary vacuum chamber with LPG.

According to the second aspect of the present invention, when the engine is started, the slow passage communicating from the primary pressure reducing chamber of the vaporizer to the LPG mixer is shut off regardless of the presence or absence of cranking. Block the passage connecting the intake pipe of the LPG
Of the vaporizer and the primary decompression chamber of the vaporizer are made conductive for a set time to sufficiently fill the primary decompression chamber with LPG.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flowchart of a start control routine, FIG. 2 is an overall configuration diagram of a fuel supply system, FIG. 3 is a cross-sectional view of a vaporizer, and FIG. 4 is a solenoid valve at engine start. O
It is a time chart which shows N and OFF.

In FIG. 2, reference numeral 1 denotes an engine,
In the present embodiment, the engine uses both LPG fuel and gasoline fuel.
A vaporizer 2 for metering gasoline and mixing it with intake air, and an adapter (L) for metering LPG and mixing it with intake air
PG mixer) 3 is interposed.

The vaporizer 2 is provided with a main cut solenoid valve 4 for cutting off the supply of gasoline stored in a float chamber (not shown). The float chamber is connected to a gasoline tank 6 via a fuel pipe 5. ing. When the main cut solenoid valve 4 is turned on and opened, the fuel pump 7 sends gasoline in the gasoline tank 6 to the float chamber of the carburetor 2 via the filter 8, and surplus gasoline is returned to the return pipe. 9 through the gasoline tank 6
Is returned to

On the other hand, the adapter 3 is connected to a vaporizer 11 via a low pressure pipe 10, and this vaporizer 11 is connected to an LPG cylinder 13 via a high pressure pipe 12. The high-pressure pipe 12 is provided with an LPG solenoid valve 14 as a first solenoid valve formed of an electromagnetic two-way valve with a built-in filter, and when the LPG solenoid valve 14 is turned on when opened, The LPG stored in the LPG cylinder 13 is sent to the vaporizer 11 to be decompressed and regulated, and supplied to the adapter 3.

The vaporizer 11 is connected to an intake pipe 1a downstream of the carburetor 2 via a negative pressure passage 15 in order to close a valve inside and release a vacuum lock for preventing the LPG from flowing out when the engine is stopped. In the negative pressure passage 15, a vacuum lock solenoid valve 16 as a third solenoid valve including an electromagnetic three-way valve having an atmosphere port is interposed.

The above vacuum lock solenoid valve 1
Reference numeral 6 denotes a valve for delaying the release of the vacuum lock, as described later. When OFF, the valve on the side of the intake pipe 1a is closed to communicate the atmosphere port with the port on the vaporizer 11, and when ON, Then, the air port is closed to communicate the port on the vaporizer 11 side with the port on the intake pipe 1a side.

The vaporizer 11 has a cooling water pipe 19 branching from a cooling water pipe 18 for sending cooling water from the radiator 17 to the engine 1, and a cooling water for sending cooling water from the engine 1 to the radiator 17. A cooling water pipe 21 that joins the water pipe 20 is connected, and hot water is guided to a hot water passage (not shown) inside the vaporizer 11 to stabilize LPG vaporization.

Further, the vaporizer 11 has an OF
A slow cut solenoid valve 22 as a second solenoid valve that closes at F and cuts fuel in the slow system, and a water temperature switch 23 that is turned on when the temperature exceeds a set temperature (for example, 10 ° C.) are attached. The slow cut solenoid valve 22 and the water temperature switch 23 are connected to the main cut solenoid valve 4 and the L
Along with the PG solenoid valve 14, it is connected to an electronic control unit (ECU) 50.

Next, the configuration of the vaporizer 11 will be described. As shown in FIG. 3, the vaporizer 11
Is a well-known two-stage pressure reducing type pressure regulator. The high pressure LPG fuel from the LPG cylinder 13 is depressurized by the primary valve 32 connected to the diaphragm 31 of the primary pressure reducing chamber 30 and flows into the primary pressure reducing chamber 30. And the set pressure (for example, 3
The pressure is adjusted to 5 KPa). Furthermore, the L of the primary decompression chamber 30
The PG fuel is depressurized by a secondary valve 35 connected to the diaphragm 34 of the secondary decompression chamber 33, adjusted to a pressure slightly lower than the atmospheric pressure, and supplied to the adapter 3 of the engine 1.

A slow passage 36 is provided between the primary pressure reducing chamber 30 and the secondary pressure reducing chamber 33. A slow passage for adjusting the mixing ratio of the engine 1 during idling is provided in the slow passage 36. The adjusting screw 37 and the above-described slow cut solenoid valve 22 are interposed.

Further, a vacuum lock chamber 39 partitioned by a diaphragm 38 is provided in the secondary decompression chamber 33.
While the vacuum lock chamber 39 is open to the atmosphere, the built-in spring urges the secondary valve 35 in the closing direction to perform vacuum lock for preventing LPG outflow when the engine is stopped. When the intake pressure of the engine 1 is introduced, the diaphragm 38 acts in a direction to open the secondary valve 35 against the urging force of the spring to release the vacuum lock.

In the fuel supply system of the engine 1 having the above configuration, an ignition switch (not shown) is turned on,
When the power is supplied to the ECU 50 and the system is initialized, the ECU 50 detects the ON / OFF state of the water temperature switch 23 of the vaporizer 11, and selects the fuel for starting the engine according to the temperature.

In this case, before the engine is started, the LPG solenoid valve 14 and the slow cut solenoid valve 22 are both closed, and the vacuum lock solenoid valve 16 is OFF, so that the vacuum lock chamber 39 of the vaporizer 11 is in the atmosphere. And the secondary valve 35 of the secondary decompression chamber 33 is closed, so that the primary decompression chamber 30 of the vaporizer 11 is a closed space.

Therefore, LP as fuel when starting the engine
When G is selected, the ECU 50 controls the ON / OFF timing of each of the solenoid valves 14, 16, and 22 so that the primary decompression chamber 30 is sufficiently filled with LPG to a set pressure before cranking. The following E
The starting control by the CU 50 will be described with reference to the flowchart of FIG.

The start control routine shown in FIG. 1 is executed after an ignition switch (not shown) is turned on to supply power to the ECU 50 and the system is initialized. First, at step S11, the water temperature switch 23 is turned on. Check if it is

As a result, when the water temperature switch 23 is OFF, that is, when the cooling water temperature of the vaporizer 11 is lower than the set temperature (for example, 10 ° C.) and it is difficult to sufficiently vaporize LPG. Then, the process proceeds from step S11 to step S12 in order to select gasoline as fuel at the time of engine start, and turns on the main cut solenoid valve 4 of the carburetor 2 while keeping the LPG solenoid valve 14 in the OFF (closed) state. finish.

As a result, the LPG solenoid valve 14
When the LPG supply from the LPG cylinder 13 is shut off, the main cut solenoid valve 4 is opened and the gasoline stored in the float chamber of the carburetor 2 can be supplied. Is started using the fuel as the fuel.

On the other hand, the water temperature switch 2
When 3 is ON, LP is used as fuel when starting the engine.
In order to select G, the process proceeds from step S11 to step S13, and the main cut solenoid valve 4 of the carburetor 2 is turned off.
With the F (valve closed) state, the LPG solenoid valve 1
When 4 is turned on (opened), it is checked in step S14 whether the engine 1 has been cranked from the ON / OFF state of a starter switch (not shown).

When the engine 1 is not cranked, the process proceeds from the step S14 to the step S15 to clear the flag F indicating the execution of the cranking (F
← 0) Proceed to step S17, and when the engine 1 is cranked, proceed from step S14 to step S16 to set the flag F (F ← 1) and proceed to step S17.

In step S17, it is checked whether or not the set time T has elapsed since the LPG solenoid valve 14 was turned on. If the set time T has not been reached, the process returns to step S14 regardless of the presence or absence of cranking. Set time T
And when the set time T is reached, step S18
The process proceeds to and checks whether or not cranking is being performed by referring to the value of the flag F.

If F = 0 in step S18 and the LPG solenoid valve 14 is turned on and cranking is not performed even after the set time T has elapsed,
Proceeding from step S18 to step S19, the LPG solenoid valve 14 is once turned off, and the process returns to step S14.

On the other hand, in the above step S18, F = 1,
After turning on the LPG solenoid valve 14, the set time T
Has elapsed and the cranking has been performed, the process proceeds from step S18 to step S20, and after the set time T has elapsed since the LPG solenoid valve 14 was
In order to cope with the case where the G solenoid valve 14 is turned off and then cranked, it is checked whether or not the LPG solenoid valve 14 is currently on.

Then, the LPG solenoid valve 14 is
When N is not determined, the process proceeds from step S20 to step S21 to turn on the LPG solenoid valve 14, and then proceeds to step S22. When the LPG solenoid valve 14 is turned on, the process proceeds from step S20 to step S22. . In step S22, the slow cut solenoid valve 4 and the vacuum lock solenoid valve 16 are turned on, and the routine ends.

That is, as shown in FIG. 4A, when the ignition switch is turned on, only the LPG solenoid valve 14 is turned on while the vacuum lock solenoid valve 16 and the slow cut solenoid valve 22 are kept off. However, in order to keep the ON state during the set time T, it is possible to prevent the backflow of air to the primary decompression chamber 30 of the vaporizer 11 and the outflow of LPG from the slow system, thereby sufficiently filling the primary decompression chamber 30 with LPG. If cranking is performed in this state, the LPG fuel at the set pressure is supplied to the adapter 3
To start the engine easily.

Also, as shown in FIG. 4B, even if cranking is started immediately after the ignition switch is turned on, the ON of the vacuum lock solenoid valve 16 and the slow cut solenoid valve 22 is delayed, and L
Since the PG solenoid valve 14 is kept on until the set time T elapses after the PG solenoid valve 14 is turned on, the vaporizer 1
The engine can be easily started without the air flowing back into the first primary decompression chamber 30 to be in a fuel-lean state.

The release of the vacuum lock may be delayed by a mechanical speed control valve (pressure delay valve) instead of the vacuum lock solenoid valve 16 which is a three-way solenoid valve.

[0038]

As described above, according to the present invention, when the engine is started, regardless of the presence or absence of cranking, the slow passage communicating with the LPG mixer from the primary pressure reducing chamber of the vaporizer is cut off, or the slow passage is provided. To shut off the passage connecting the vacuum lock chamber of the vaporizer and the intake pipe of the engine, and keep the passage connecting the cylinder storing the LPG and the primary decompression chamber of the vaporizer for a set time. For the primary decompression chamber of the vaporizer, which becomes one closed space,
It is possible to prevent the air inflow and the LPG outflow at the time of starting the engine, sufficiently fill the primary decompression chamber with LPG, and obtain excellent effects such as improvement of the startability.

[Brief description of the drawings]

FIG. 1 is a flowchart of a start control routine.

FIG. 2 is an overall configuration diagram of a fuel supply system.

FIG. 3 is a sectional view of a vaporizer.

FIG. 4 shows ON and OFF of each solenoid valve when the engine is started.
Time chart showing OFF

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine 3 ... Adapter (LPG mixer) 13 ... LPG cylinder 14 ... LPG solenoid valve (first solenoid valve) 16 ... Vacuum lock solenoid valve (third solenoid valve) 22 ... Slow cut solenoid valve (second solenoid) valve)

Claims (2)

[Claims] 1. A first solenoid valve for conducting / cutting off a passage connecting a cylinder for storing LPG and a primary decompression chamber of a vaporizer, and a slow passage communicating from the primary decompression chamber of the vaporizer to an LPG mixer. A second solenoid valve for shutting off, wherein when starting the engine, the second solenoid valve is kept closed and the first solenoid valve is opened for a set time regardless of the presence or absence of cranking. An engine start control device comprising control means. 2. A first valve for conducting and shutting off a passage connecting a cylinder for storing LPG and a primary decompression chamber of a vaporizer, and a slow passage for communicating the LPG mixer from the primary depressurization chamber of the vaporizer to an LPG mixer. A second valve for turning on and off a passage connecting the vacuum lock chamber of the bar paralyzer and an intake pipe of the engine. An engine start control device comprising: a start control unit that keeps the solenoid valve and the third valve closed and opens the LPG solenoid valve for a set time.