JPS6115265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for supplying additional fuel to an engine during engine starting and acceleration.

The carburetor in the engine is provided with an acceleration pump that is linked to the accelerator pedal to supply additional fuel when starting the engine (particularly when starting cold) and during acceleration. In this case, the conventional acceleration pump connects the acceleration nozzle for supplying fuel from the acceleration pump to the intake path upstream of the throttle valve in the carburetor or to the intake path downstream of the throttle valve and close to the throttle valve. For example, it is disclosed in Japanese Utility Model Application Publication No. 48-65916 that the additional fuel is mixed with the intake air passing through the carburetor's ventilate and introduced into the combustion chamber of the engine through the intake manifold along with the intake air. It is as described. However, when starting the engine (particularly when starting cold) and when the engine is in a low load/low engine speed range, the amount of intake air passing through the carburetor is small and the temperature is low enough to vaporize the additional fuel from the accelerator pump. Therefore, the additional fuel adheres to the inner wall surface of the carburetor and intake manifold and flows along the inner wall surface, causing a considerable time delay before it reaches the combustion chamber. The effect of improving startability and acceleration in the low load/low rotation range cannot be fully achieved.In particular, in order to lower the overall height of the engine, the carburetor mounting seat must be placed at a location lower than the engine intake port. In the case of engines for cab-over type vehicles installed in Since fuel from the slow system of the carburetor accumulates, engine startability and acceleration performance in low load/low rotation ranges are extremely poor, and the supercharger is driven by exhaust gas. In other words, in an engine equipped with an exhaust gas turbocharger, when fuel is supplied by a carburetor, the blower compressor of the turbocharger is installed in the intake passage from the carburetor to the engine, and the The intake passage is longer, and fuel accumulates in the casing of the blower compressor and adheres to the impeller, so the startability and acceleration in low load and low rotation ranges of turbocharged engines are lower than those of the cab-over type. It was as low as in the case of vehicle engines.

Therefore, Japanese Utility Model Publication No. 53-30584 as a prior art proposes to provide an acceleration nozzle for supplying fuel from an acceleration pump to the intake port of the engine. Providing an acceleration nozzle in the intake port of the engine can prevent a delay in the acceleration fuel when starting the engine or in a low load/low rotation range, but if the engine is a multi-cylinder engine having multiple cylinders, Due to the proximity of the fuel supply acceleration nozzle to the combustion chamber, the additional acceleration fuel supplied from the fuel supply acceleration nozzle cannot be equally guided to each cylinder. This causes the air-fuel ratio to vary, which not only reduces acceleration but also worsens drivability.

According to the present invention, it is necessary to distribute the acceleration fuel equally to each cylinder, especially when accelerating after starting the engine, while the delay in supplying the acceleration fuel to the combustion chamber is necessary when the engine is started or at low engine speeds.・
Considering that this phenomenon is noticeable in low load ranges, the fuel supply system from the accelerator pump in the carburetor is divided into two systems, and when starting the engine or in low load/low rotation ranges, the fuel supplied by the accelerator pump is routed to the part near the intake port. However, at the time of starting or in operating ranges other than the low load/low rotation range, the fuel from the accelerator pump is supplied to the part upstream of the throttle valve as in the past, thereby solving the above problem. It is.

Next, we will explain the drawings of an embodiment in which one example of the present invention is applied to a turbocharged engine. After starting, fuel is supplied from the acceleration nozzle upstream of the throttle valve. In this figure, 1 indicates the engine body, 2 indicates the blower compressor in the turbo supercharger,
The blower compressor 2 is installed at a position lower than the intake port 3 in the cylinder head of the engine body 1, and has a vent 6, a main nozzle 7, and a throttle valve 8 at the upper end of the intake pipe 4 of the blower compressor 2. 5 is attached, and the discharge pipe 9 of the blower compressor 2 is connected to the intake manifold 10.
It is connected to the intake port 3 via.

Reference numeral 11 denotes an acceleration pump which is operated via a lever 12 when the throttle valve 8 is suddenly opened.
The acceleration pump 11 communicates with a float chamber 14 via an intake check valve 13, and a fuel supply passage 15 from the acceleration pump 11 is connected to a main passage 16 and a sub passage 17.
One main passage 16 is connected to an acceleration nozzle 18 provided near the ventilate 6 on the upstream side of the throttle valve 8 in the carburetor 5.
9, and the other sub passage 17 is connected to a port 20 provided in a portion of the intake manifold 10 near the intake port 3, and the main passage 16 has a spherical valve body 21 and a discharge weight 22. A check valve 23 made up of
In step 2, the check valve 23 is kept normally closed by pressing the weight 22, and the weight 22 is closed by energizing.
A solenoid 27 is provided to release the pressure of the
A normally open pressure switch 30 installed in the lubricating oil system (not shown) in the engine body 1 is provided in the circuit 29 connecting the solenoid 27 and the battery 28, so that when the engine starts, the lubricating oil pressure increases. If so, the solenoid 27 is configured to be energized when the pressure switch 30 is turned on.

The intake manifold 10 is substantially horizontal or has a downward slope in the direction of the intake port 3, and has a convex portion 31 on the bottom surface of the intake manifold 10 to prevent the fuel supplied from the port 20 from flowing back toward the blower compressor 2. It is provided.

In this configuration, when the engine is stopped, the pressure switch 30 is OFF, and the solenoid 27 is in the main passage 1.
6 is held closed, and the fuel supply passage 15 from the acceleration pump 11 communicates only with the port 20 of the intake manifold 10 via the auxiliary passage 17. When the accelerator pedal is activated, the accelerator pump 11 is activated in conjunction with this, and the fuel from the accelerator pump 11 bypasses the blower compressor 2 from the port 20 and is delivered to a location near the intake port 3 of the engine. supplied directly to

When the engine starts, the lubricating oil pressure becomes high and the pressure switch 30 is turned on, energizing the solenoid 27, which releases the check valve 23 from being held closed, so that the fuel supply passage 15 from the acceleration pump is the main It communicates with an acceleration nozzle 18 through a passage 16, and when the acceleration pump is activated after the engine has started, the fuel is supplied to the acceleration nozzle 1 upstream of the throttle valve 8.
The check valve 26 in the auxiliary passage 17 prevents fuel from being sucked into the intake manifold 10 when the engine load is low or during deceleration, and also prevents fuel from being sucked out to the intake manifold 10 when the engine load increases. Accordingly, when the boost pressure of the intake manifold 10 increases, the boost pressure is transferred from the port 20 to the acceleration pump 11.
This acts to prevent unnecessary fuel from leaking out from the acceleration nozzle 18 and the like.

In this case, instead of being related to the throttle valve 8 and the accelerator pedal, the acceleration pump 11 may be constructed so that it operates when the starter of the engine is operating, and may also be used as a means for detecting engine starting. is not limited to the lubricating oil pressure, but other means such as the engine cooling water pressure or the temperature of the lubricating oil or cooling water can be used.

In the embodiment shown in Fig. 2, fuel is supplied from the accelerator pump to a part of the engine near the intake port when the engine is cold started and in a low load/low rotation range, and in other load ranges, fuel is supplied upstream from the throttle valve. Fuel is supplied from the acceleration nozzle on the side. To explain the diagram, a pressure switch 32 and a temperature-sensitive switch 33 provided on the intake manifold 10 are inserted into the circuit 29 connecting the solenoid 27 and the battery 28, and the engine temperature is raised to a certain temperature or higher (for example, 10 degrees Celsius or higher). If this occurs, the temperature sensitive switch 33 is turned on, and the pressure in the intake manifold 10 becomes higher than a certain value, and the pressure switch 32 is turned on, thereby energizing the solenoid 27. In other words, when the engine is cold-started, the temperature-sensitive switch 33 is
Pressure switch 3 is turned OFF in low load/low rotation range.
2 is OFF, so the solenoid 27 is the check valve 23.
is held closed, all fuel from the acceleration pump 11 is directly supplied from the port 20 to a portion near the intake port 3, bypassing the blower compressor 2. When the engine is running and the engine temperature rises, the temperature-sensitive switch is turned on, and when the boost pressure of the intake manifold increases as the load and rotation speed increase, the pressure switch 32 is also turned on. Then, the solenoid 27 releases the closed hold of the check valve 23, so the fuel from the acceleration pump is transferred to the acceleration nozzle 18.
It is supplied to the upstream side of the throttle valve.

In this case, cooling water temperature, lubricating oil temperature, etc. can be used as the engine temperature detection means, and other means such as engine exhaust gas pressure or engine rotation speed can be used as the load/rotational speed detection means. be able to. It goes without saying that the present invention is not limited to the turbocharged engine of the embodiment described above, but is equally applicable to ordinary engines in which the carburetor is directly attached to the intake manifold.

As described above, the present invention provides an engine in which a carburetor with a throttle valve is attached to an intake manifold connected to an intake port of the engine, in which an acceleration fuel supply passage from an acceleration pump in the carburetor is branched into two passages. One of the two passages is used as a sub-passage for supplying acceleration fuel to a portion close to the intake port at the time of starting the engine or in a low load/low rotation range, and the other passage is designated as a sub passage for supplying acceleration fuel to a portion close to the intake port at the time of starting the engine or in a low load/low rotation range.・It is configured in the main passage that supplies acceleration fuel to the part upstream of the throttle valve in operating ranges other than low-speed ranges, and when starting the engine or in operating ranges other than low-load/low-speed ranges,
By supplying acceleration fuel to the upstream side of the throttle valve, acceleration fuel can be distributed approximately equally to multiple cylinders, improving acceleration performance when starting the engine or in operating ranges other than low load/low rotation ranges. While it is possible to improve drivability and prevent deterioration of drivability during acceleration, when starting the engine or in a low load/low rotation range, by supplying acceleration fuel to the part near the intake port, It is possible to avoid delays in the supply of acceleration fuel when starting the engine or in the low load/low rotation range, so even if the engine is a cab-over type vehicle engine or a turbocharged engine, the engine starts easily. Or, it has the effect of reliably improving acceleration performance in the low load/low rotation range.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a device according to a second embodiment of the present invention. 1...Engine body, 2...Blower compressor,
5... Carburetor, 8... Throttle valve, 10... Intake manifold, 3... Intake port, 11... Accelerator pump, 15... Fuel supply passage, 16... Main passage, 17... Sub passage, 18 ...Acceleration nozzle, 20
……port.

Claims (1)

[Claims] 1. In an engine in which a carburetor with a throttle valve is attached to an intake manifold connected to an intake port of the engine, an acceleration fuel supply passage from an acceleration pump in the carburetor is branched into two passages, and one of these two passages is One passage is used as an auxiliary passage for supplying acceleration fuel to a portion close to the intake port at the time of starting the engine or in a low load/low rotation range, and the other passage is used for supplying acceleration fuel to a portion close to the intake port at the time of starting the engine or in a low load/low rotation range. 1. A fuel supply device for an engine, characterized in that the main passage is configured to supply acceleration fuel to a portion upstream of a throttle valve in an operating range.