JP2006194208A - Electronic fuel injection type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic fuel injection type engine which can suppress engine failure due to overshoot on the valve closing side of a throttle valve. <P>SOLUTION: In the electronic fuel injection type engine formed such that a throttle valve 2 is situated in an intake route 1, the throttle valve 2 is interlocked with and coupled to a mechanical governor 3, and a control means 7 adjusts an amount of fuel injected from an injector 4 based on an air intake pressure on the downstream side of the throttle valve 2 detected by an intake air pressure sensor 5 and the engine speed detected by an engine speed sensor 6, the engine is provided with an intake air bypass passage through which the upstream side is communicated with the downstream side and the bypass valve 9 which opens and closes the intake air bypass passage 8, the bypass valve 9 being associated with the control means, and in case a decreasing speed of an intake air pressure detected by the intake air pressure sensor 5 is higher than a given value, the bypass valve 9 is opened through control of the control means 7 for a given time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic fuel injection type engine, and more particularly to an electronic fuel injection type engine capable of suppressing engine stall due to overshoot on the valve closing side of a throttle valve.

As a conventional electronic fuel injection type engine, as in the present invention, a throttle valve is provided in the intake path, this throttle valve is linked to a mechanical governor, and an injector for injecting fuel to the intake downstream side of the throttle valve, and a throttle valve An intake pressure sensor for detecting an intake pressure on the downstream side of the intake air, an engine speed sensor, and a control means are provided, and the intake pressure sensor and the engine speed sensor are linked to the injector via the control means. There is one in which the control means adjusts the fuel injection amount from the injector based on the intake pressure detected in step 1 and the engine speed detected by the engine speed sensor (see, for example, Patent Document 1).
In this type of engine, the opening of the throttle valve is adjusted with a mechanical governor, and the fuel mixture is supplied to the combustion chamber with a concentration and quantity that matches the engine operating conditions by adjusting the fuel injection amount based on the intake pressure and engine speed. Can be done.

  In this type of engine, the throttle valve is controlled by a mechanical governor, so there is an advantage that it can be manufactured at a lower cost compared to the case where an electronic governor is used. ing.

Japanese Patent Laid-Open No. 11-93730 (see FIG. 1)

The above prior art has the following problems.
<Problem> Enst is likely to occur.
When the load suddenly decreases, the throttle valve overshoots to the closed side due to the operation of the mechanical governor. In the above prior art, since the intake air amount depends only on the opening of the throttle valve, at the time of overshoot, the intake air amount is insufficient, a sufficient amount of air-fuel mixture cannot be obtained, and engine stall is likely to occur.

  An object of the present invention is to provide an electronic fuel injection engine capable of solving the above-described problems, that is, an electronic fuel injection engine capable of suppressing engine stall due to overshoot on the valve closing side of the throttle valve. And

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIGS. 1A and 1B, a throttle valve (2) is provided in the intake passage (1), and this throttle valve (2) is linked to a mechanical governor (3) to connect a throttle valve (2 ), An injector (4) for injecting fuel to the intake downstream side, an intake pressure sensor (5) for detecting the intake pressure on the intake downstream side of the throttle valve (2), an engine rotation sensor (6), and control means ( 7), the intake pressure sensor (5) and the engine speed sensor (6) are linked to the injector (4) via the control means (7), and the intake pressure detected by the intake pressure sensor (5) In the electronic fuel injection engine, the control means (7) adjusts the fuel injection amount from the injector (4) based on the engine speed detected by the engine speed sensor (6).
An intake bypass passage (8) for communicating the upstream side and the downstream side of the throttle valve (2) and a bypass valve (9) for opening and closing the intake bypass passage (8) are provided. When the rate of decrease of the intake pressure detected by the intake pressure sensor (5) is greater than a predetermined value in cooperation with the control means (7), the bypass valve (9) is controlled for a predetermined time by the control of the control means (7). An electronic fuel injection engine characterized by opening the valve.

(Invention according to Claim 1)
<Effect> The engine stall can be suppressed.
When the throttle valve (2) overshoots on the valve closing side, the valve closing speed is high from the beginning of the valve closing operation, and the rate of decrease of the intake pressure on the downstream side of the throttle valve (2) is also large. In the present invention, the sign of the overshoot is detected from the magnitude of the reduction speed of the intake pressure, and the bypass valve (9) is opened. Therefore, the intake bypass passage (8) is opened before the throttle valve (2) is overshot. It can be opened and replenished quickly. For this reason, there is no problem that the intake air amount is insufficient even at the time of overshoot, a sufficient amount of air-fuel mixture is obtained, and engine stall can be suppressed.

(Invention according to Claim 2)
In addition to the effect of the invention according to claim 1, the following effect is achieved.
<Effect> The engine stall suppressing function can be enhanced.
When the load reduction rate is large, the degree of overshooting of the throttle valve (2) toward the valve closing side increases, so that the return of the throttle valve (2) to the proper opening is delayed, and engine stalling is likely to occur. In the present invention, the function of suppressing such engine stall can be enhanced.
The reason is as follows. When the degree of overshoot increases, the valve closing speed at the initial valve closing time is relatively large, and the rate of decrease of the intake pressure at the initial valve closing time is also relatively large. In the present invention, this is detected as a sign of an increase in the degree of overshoot and the valve opening time of the bypass valve (9) is lengthened, so the intake replenishment period is lengthened and the engine stall suppression function can be enhanced. It is.

(Invention according to claim 3)
In addition to the effect of the invention according to claim 1 or claim 2, the following effect is achieved.
<Effect> The intake bypass passage and the bypass valve can also be used as a means for promoting cold start and a means for stabilizing idling during cold weather.
When the engine temperature is lower than the predetermined value, the bus pass valve (9) is opened for a predetermined time. Therefore, the fuel injection amount is increased by the amount of intake air replenished from the intake bypass passage (8), and the cold start is started. And stabilization of idling during cold weather. For this reason, the intake bypass passage (8) and the bypass valve (9), which are engine stall suppression means, can also be used as cold start promoting means and idling stabilization means during cold weather.

  Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are diagrams for explaining an electronic fuel injection engine according to an embodiment of the present invention. In this embodiment, a vertical water-cooled two-cylinder serial electronic fuel injection engine will be described.

The outline of the engine according to the embodiment of the present invention is as follows.
As shown in FIG. 2, the cylinder head (12) is assembled to the upper part of the cylinder block (11), and the head cover (13) is assembled to the upper part of the cylinder head (12). A gear case (14) is assembled to the front part of the cylinder block (11), a belt case (15) is assembled to the front part of the gear case (14), and a cooling fan (16) is arranged at the front part of the belt case (15). Yes. A flywheel (17) is disposed at the rear of the cylinder block (11).

The outline of the electronic fuel injection device is as follows.
As shown in FIGS. 1 (A) and 1 (B), a throttle valve (2) is provided in the intake passage (1), and the throttle valve (2) is linked to a mechanical governor (3) to connect the throttle valve (2). An injector (4) for injecting fuel to the intake downstream side of the engine, an intake pressure sensor (5) for detecting intake pressure on the intake downstream side of the throttle valve (2), an engine rotation sensor (6), and control means (7 ), The intake pressure sensor (5) and the engine speed sensor (6) are linked to the injector (4) via the control means (7), and the intake pressure detected by the intake pressure sensor (5) Based on the engine speed detected by the engine speed sensor (6), the control means (7) adjusts the amount of fuel injected from the injector (4).
According to this electronic fuel injection device, the opening degree of the throttle valve (2) is adjusted by the mechanical governor (3), and the control means (7) adjusts the fuel injection amount based on the intake pressure and the engine speed. Supply the combustion chamber with a gas mixture of a concentration and quantity suitable for engine operating conditions.

Details are as follows.
As shown in FIG. 1 (A), the intake passage (1) includes an air cleaner (not shown), a throttle valve passage (18), and an intake port (19). The throttle valve passage (18) is provided in the throttle body (20), and the throttle valve (2) is provided in the throttle valve passage (18). The intake port (19) is provided in the cylinder head (12), and is V-shaped toward the intake valve ports (23) and (23) of the two cylinders (22) and (22) from the single inlet (21). The structure of the mold. A passage outlet of the throttle valve passage (18) is connected to the inlet (21) of the intake port (19). An air cleaner is communicated with the passage inlet of the throttle valve passage (18). As shown in FIG. 2, the governor lever (24), the governor spring (25), and the interlocking rod (26) of the mechanical governor (3) interlockingly connecting the throttle valve (2) are located next to the cylinder block (11). Arranged on the side. A governor weight (not shown) for applying a governor force to the governor lever (24) is housed inside the engine.

  As shown in FIG. 1 (B), the injector (4) is attached to the upper part of the throttle body (20). As shown in FIG. 2, the injector (4) is connected to a fuel pump (26) provided in the fuel tank (25). Fuel is pumped from the fuel tank (25) to the injector (4) by a fuel pump (26). Then, the fuel injection amount is adjusted by controlling the fuel injection period from the injector (4) by the control means (7). The control means (7) is a microcomputer.

The device of the electronic fuel injection device is as follows.
As shown in FIGS. 1A and 1B, an intake bypass passage (8) for communicating the upstream side and the downstream side of the throttle valve (2) and a bypass valve (9) for opening and closing the intake bypass passage (8). ) And the bypass valve (9) is linked to the control means (7). When the rate of decrease of the intake pressure detected by the intake pressure sensor (5) is greater than a predetermined value, the control means (7 ), The bypass valve (9) is opened for a predetermined time. The intake bypass passage (8) is formed in the passage wall of the throttle body (20). The inlet of the intake bypass passage (8) faces the air cleaner, and the outlet faces the throttle valve (2) downstream of the throttle valve passage (18).

Other ideas are as follows.
When the rate of decrease of the intake pressure detected by the intake pressure sensor (5) is larger than a predetermined value, the control means (7) controls the opening of the bypass valve (9) as the rate of decrease of the intake pressure increases. The valve time is lengthened. Further, the engine temperature detecting means (10) is linked to the control means (7), and when the engine temperature is lower than a predetermined value, the magnitude of the decrease rate of the intake pressure detected by the intake pressure sensor (5) is set. Regardless, the bus pass valve (9) is opened for a predetermined time. A cooling water temperature sensor is used for the engine temperature detection means (10), but an engine oil temperature sensor may be used instead.

1A and 1B are views for explaining an intake path of an engine according to an embodiment of the present invention, FIG. 1A is a cross-sectional plan view of the cylinder head and its periphery, and FIG. FIG. 1 is a side view of an engine according to an embodiment of the present invention.

Explanation of symbols

(1) ... intake path, (2) ... throttle valve, (3) mechanical governor, (4) injector, (5) intake pressure sensor, (6) engine speed sensor, (7) control means , (8) ... Intake bypass passage, (9) ... Bypass valve, (10) ... Engine temperature detection means.

Claims (3)

A throttle valve (2) is provided in the intake passage (1), and this throttle valve (2) is linked to a mechanical governor (3) to inject fuel into the intake downstream side of the throttle valve (2) (4) And an intake pressure sensor (5) for detecting the intake pressure downstream of the throttle valve (2), an engine rotation sensor (6), and a control means (7). The rotational speed sensor (6) is linked to the injector (4) via the control means (7), and the intake pressure detected by the intake pressure sensor (5) and the engine rotational speed detected by the engine rotational speed sensor (6). In the electronic fuel injection engine in which the control means (7) adjusts the fuel injection amount from the injector (4) based on
An intake bypass passage (8) for communicating the upstream side and the downstream side of the throttle valve (2) and a bypass valve (9) for opening and closing the intake bypass passage (8) are provided. When the rate of decrease of the intake pressure detected by the intake pressure sensor (5) is greater than a predetermined value in cooperation with the control means (7), the bypass valve (9) is controlled for a predetermined time by the control of the control means (7). An electronic fuel injection engine characterized by opening the valve. The electronic fuel injection engine according to claim 1,
When the rate of decrease of the intake pressure detected by the intake pressure sensor (5) is larger than a predetermined value, the control means (7) controls the opening of the bypass valve (9) as the rate of decrease of the intake pressure increases. An electronic fuel injection engine characterized in that the valve time is extended. The electronic fuel injection engine according to claim 1 or 2,
When the engine temperature detection means (10) is linked to the control means (7) and the engine temperature is lower than a predetermined value, the intake pressure sensor (5) detects the rate of decrease in the intake pressure regardless of the magnitude. An electronic fuel injection engine characterized in that the bypass valve (9) is opened for a predetermined time.

Images