JPH0392575A - Control device for engine - Google Patents

Abstract

PURPOSE:To smoothly reduce the output with no torque shock with a simple and inexpensive structure by switching the fuel fed to an engine from gasoline to LPG when the engine attains the preset rotating speed. CONSTITUTION:A control device 24 judges whether the detected value of an engine rotating speed detecting means 26 is larger than the relatively high preset value or not while an engine 1 is operated. If the judged result is 'Yes', a selector switch 21 is controlled to open a switching valve 22 and close a switching valve 23. The fuel fed to the engine 1 is switched from gasoline in a tank 19 to LPG in a bottle 10. If the judged result is 'No', the switching valve 22 is closed, the switching valve 23 is opened, and gasoline is continuously fed. If the detected value of the engine rotating speed is the relatively low preset value or below while LPG is fed, the fuel is again switched from LPG to gasoline.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device, and more particularly to a control device that switches fuel supply to an engine between gasoline and LPG.

(Prior Art) Conventionally, when switching the fuel supply to an engine between gasoline and LPG, there is a system in which the switching is performed manually depending on the operating condition. (For example, JP-A-57-1025
(Publication No. 47) (Problem to be solved by the invention) As mentioned above, when switching between gasoline and LPG is performed manually according to the operating conditions such as load, gasoline fuel is normally used on the high load side. , the engine is for example 700r
When the guaranteed rotation of ps+ is exceeded, control such as secondary valve control is required.

In the case of secondary valve control, since one throttle valve is closed, there is a problem that the output suddenly decreases and suffers from so-called torque lock, and an actuating device such as a diaphragm type is required for secondary valve control, which increases costs. There's a problem.

In view of these points, the present invention aims to reduce the output by automatically switching the fuel from gasoline to LPG when the engine speed exceeds a predetermined speed. The object of the present invention is to provide a control device for an engine.

(Means for Solving the Problems) As shown in FIGS. 1 to 3 of the embodiment drawings, the present invention selectively supplies fuel to an engine (1) between gasoline and LPG depending on the operating condition. In this engine control device, the engine (1) is switched from gasoline to LPG when it is detected by the rotation speed detection means (26) that the engine (1) is at a predetermined rotation speed (NA) or higher. (Function) When the engine (1) exceeds a predetermined rotational speed (NA) by the engine control device, the fuel supply is automatically switched from gasoline to LPG, and the engine output decreases without torque shock. It's done smoothly.

An embodiment of the present invention will be explained based on the drawings. Fig. 1 is a schematic configuration diagram of the present invention, in which (1) is an engine, (2) is an intake passage, and the upstream end is connected to the atmosphere through an air cleaner (3). It is open to the side and the downstream end communicates with the combustion chamber (4) of the engine. (5) is a mixer, which is arranged in the intake passage (2) on the downstream side of the air cleaner (3), and its venturi (6) protrudes inward from the inner peripheral wall of the intake passage (2) in a semicircular shape. It has been done. One end of a fuel passage (7) is connected to the venturi (6), a vaporizer (8) and a preheater (9) are provided in the middle, and an LPG cylinder 00) is connected to the other end.

01) is a two-barrel carburetor, which is placed in the intake passage (2) downstream of the mixer (5).
It has a parallel primary intake passage and a secondary intake passage that are partitioned by partition walls 02) in ), and venturis (13a) and (13b) are formed on the upstream side of both passages, and A primary valve circle and a secondary valve θ are arranged on each side.

Gasoline is supplied to the float chamber Oω from a gasoline tank 09 via a fuel passage 08 in which a fuel pump 071 is interposed. The gasoline supplied to the float chamber 06) is supplied into the primary and secondary intake passages through nozzles formed in the venturis (13a) and (13b). Note that QΦ is a canister.

(21) is a changeover switch, which is connected to the electromagnetic on-off valve (22) provided in the fuel passage (7) via a conducting wire (22a), and is connected to the electromagnetic on-off valve (23) provided in the float chamber 0ω via a conducting wire (
It is connected via the solenoid on-off valve (23a) and can be manually operated.
2)? (23), but when a switching signal (25) is received from the control unit (ECU) (24), the solenoid on-off valve (22) or (23) is automatically switched in priority over manual operation. This switching is now taking place.

The control device (24) has input signals such as an engine rotation speed detection means (26), an LPG signal (27), a gasoline signal (28), a 0■ sensor (29), and an idle switch.
(30), water temperature sensor (31), clutch SW (3
2), Neutral SW from the transmission (
33) are respectively input, and on the other hand, there are the switching signal (25) and a signal to the fuel injection valve (34) as output signals.

With the above arrangement, the present invention operates as shown in FIGS. 2 and 3. That is, the engine is started (block l), and soon the engine speed detection means (26) detects the engine speed (EngNe) as the control device ff (24).
Among the predetermined rotational speeds, the higher setting {Ii! It is judged whether or not it is larger than (NA) (block 2), and when (EngNe) is larger than (N,) (YES), the changeover switch (21) is activated by the output signal switching signal (25) to open/close. At the same time as the valve (22) is opened, the on-off valve (23) is closed to switch from gasoline to LPG supply (block 3). On the other hand (block 2
), when (EngNe) is smaller than (Na ), (
If No), the on-off valve (22) is closed, the on-off valve (23) is kept open, and gasoline supply continues (block 4).

Also, when the LPG is supplied (block 3), (block 5
) as shown in < When (Er + gNe) is less than the lower set value (Nl ) of the specified rotational speeds as shown in Figure 3, (
YES), the on-off valve (
22) is closed, and at the same time the on-off valve (23) is opened to switch from LPG to gasoline supply (block 6).
). On the other hand, when (EngNe) is larger than (N.), (NO
), the on-off valve (22) is kept open and the on-off valve (23) is kept closed to continue LPG supply (block 7).

In addition, in Fig. 3, there are two set values (Na) for the predetermined rotation speed.
The reason for providing (N*) is to provide a time margin for the operation when switching between gasoline and LPC, so that the switching can be performed smoothly.

The above is an explanation of the case where the fuel supply is automatically switched according to the engine speed during driving, but the driver can manually switch the changeover switch (21) as needed during driving to supply LPG or gasoline. It is possible to supply.

FIG. 4 is a block diagram showing another embodiment of the present invention.

That is, the engine is started (block 1) and the water temperature sensor (31) is input to the control device (24);
Engine rotation speed detection means (26), LPG signal (27>
It is determined whether or not it is in the half-warm-up region based on the input signal of (block 2), and when it is determined (YES), the changeover switch (21) is activated by the output signal (25).
operates and closes the on-off valve (22). At the same time, the on-off valve (22) closes.
23) is opened and gasoline is supplied (block 3)
.

On the other hand, in block 2, it is not a half-warm-up region (NO
), the water temperature sensor (3l), neutral switch (33), idle sh (30), engine speed detection means (26),
Based on the input signal of the LPG signal (27), it is determined whether or not it is in the idle region (block 4), and when it is determined (YES), gasoline is supplied in the same manner as in block 2 (block 4). 3). On the other hand, when it is determined in block 4 that it is not in the idle region (NO), the changeover switch (21) is activated by the changeover signal (25), and the on-off valve (22) is opened, and at the same time the on-off valve (23) is closed. (Block 5) In other words, in the other embodiments described above, when it is detected by various detection means such as water temperature that the engine is in the idle region or semi-warm-up region, the control device (24) determines that Fuel supply is automatically switched from LPG to gasoline. Therefore, the gasoline exhaust gas purification device works well and improves the purification performance of exhaust gas.
Also, stability during idling is expected.

(Effects of the Invention) According to the present invention, when the engine speed exceeds a predetermined engine speed, the fuel supply is automatically switched from gasoline to LPG, so the output decreases less than when using secondary valve control. This is done smoothly without any torque shock. Furthermore, since no secondary valve control is required, the cost is reduced accordingly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. FIG. 4 is a block diagram showing another embodiment of the present invention. 1. Engine 10. LPG cylinder 19.
Gasoline tank 21...Switch switch 22.23
・・74'fl open/close valve 24 ・・ilt'4B device 2
5...Switching signal 4 Figure 2 Figure 3 Figure Nlj → High rotation

Claims (1)

[Claims] In an engine control device that supplies fuel to an engine by selectively switching between gasoline and LPG depending on the operating state, when the engine speed detecting means detects that the engine speed is higher than a predetermined speed, gasoline is supplied to the engine. An engine control device characterized in that it can be switched to LPG.