JP3269338B2 - Fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

[0002]

The present invention relates to a gaseous fuel, LPG.
The present invention relates to a fuel supply device that mixes air with air and supplies the mixture to an engine.

[0003]

2. Description of the Related Art As is well known, a fuel supply device for an engine using LPG as a fuel includes a vaporizer and a carburetor. During normal operation, fuel is supplied to the intake passage from a fuel nozzle opened to the venturi by intake negative pressure generated in the venturi of the carburetor. However, during idle operation, the intake negative pressure generated in the venturi is low, so that it has been difficult to supply fuel to the intake passage. Therefore, the vaporizer is activated by the intake negative pressure generated downstream of the throttle valve during idling operation,
Idle operation fuel supply means for supplying fuel to the intake passage, and normal operation fuel supply means for supplying fuel to the intake passage operated by the intake negative pressure generated in the venturi during normal operation, are provided in parallel. 2. Description of the Related Art There is known an LPG fuel supply device that supplies fuel required in an entire operation range of an engine to an intake passage by switching fuel supply means according to an operation state.

[0004]

However, in the above-described fuel supply device, when the operation shifts from the idling operation at the time of starting or the like to the normal operation, that is, when the throttle valve is at a minute opening, the amount of air sucked into the combustion chamber. However, there is a problem in that there is a time loss until the intake negative pressure required for operating the fuel supply unit during normal operation of the vaporizer is obtained, and the air-fuel mixture is temporarily thinned and the combustion state becomes unstable. .
In particular, there is a problem that torque is insufficient at the time of starting acceleration, acceleration performance at starting is low, and drivability is low.
In addition, there is a problem that the accelerator is depressed in order to solve the torque shortage, and the fuel efficiency is reduced. Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a fuel supply device that stabilizes a combustion state at the time of starting and improves acceleration at the time of starting.

[0005]

According to the first aspect of the present invention, an LP is provided.
A throttle valve provided in an intake passage communicating with a combustion chamber of an engine using G as a fuel, a venturi provided upstream of the throttle valve in the intake passage and having a fuel nozzle, and a fuel supply source for supplying LPG fuel; A fuel passage connecting the fuel nozzle, a fuel supply passage provided in the fuel passage, for supplying fuel to the fuel nozzle during idling operation, and a fuel supply device for idling operation; And a normal operation fuel supply means for supplying the fuel to the fuel nozzle, wherein the throttle valve is opened at a predetermined angle with respect to the intake passage upstream of the throttle valve when the throttle valve is closed. With respect to the upstream fuel port provided at a position downstream of the throttle valve at the time and the intake passage,
A downstream fuel port provided downstream of the throttle valve when the throttle valve is closed has one end communicating with the upstream fuel port and the downstream fuel port, and the other end has a fuel nozzle and both fuel supply ports. And an auxiliary fuel passage communicating with the fuel passage between the fuel supply means and the fuel supply means, and the fuel supply means during normal operation is set so as to be operated by the intake negative pressure generated in the venturi.

According to a second aspect of the present invention, in the fuel supply device according to the first aspect, an upstream fuel port is provided upstream of the auxiliary fuel passage, and a downstream fuel port is provided downstream thereof. Configuration.

[0007] In has it <br/> the fuel supply apparatus according to claim 1 or 2, wherein the predetermined angle can also be between 1-5 degrees
You.

According to a third aspect of the present invention, in the fuel supply device according to the first or second aspect , the auxiliary fuel passage is provided with a fuel through-hole having a larger flow resistance than the fuel passage.

The invention of claim 4 is the invention of claim 1, 2 or 3
In the fuel supply device described above, a pressure reducing valve for reducing and evaporating LPG fuel pressure-fed from a fuel supply source is provided upstream of the fuel supply means during idle operation and the fuel supply means during normal operation in the fuel passage. Configuration.

[0010]

FIG. 1 shows an embodiment of the present invention, and this embodiment will be described. In FIG. 1, reference numeral 1 denotes a carburetor that generates a mixture of LPG, which is a gaseous fuel, and air.
The carburetor 1 is connected to an air cleaner (not shown) on the upstream side and an engine (not shown) on the downstream side.

The carburetor 1 has an intake passage 2 penetrating the main body of the carburetor 1, a throttle valve 3 provided in the intake passage 2 for adjusting the amount of air-fuel mixture supplied to a combustion chamber of the engine, A venturi 4 that narrows a part of the intake passage 2 to increase the intake air flow in this part; a fuel nozzle 5 that is opened to the venturi 4 and supplies fuel to the intake passage 2; It mainly comprises a fuel passage 6 and an auxiliary fuel passage 7 for stabilizing the amount of fuel supplied to the engine when shifting from idling operation to normal operation. Throttle valve 3
Keeps a substantially fully closed state when the engine is stopped and during idling.

The fuel nozzle 5 is connected to the other end of a fuel passage 8 whose one end is connected to a known vaporizer 10. The fuel passage 8 is provided with a fuel measuring means 8b for measuring the fuel amount to the fuel nozzle 5, and a fuel amount correcting means 8a for correcting the fuel amount based on the fuel composition of the LPG.

The vaporizer 10 is composed of idle operation fuel supply means 11 for supplying fuel to the fuel nozzle 5 during idle operation, and normal operation fuel supply means 17 for supplying fuel to the fuel nozzle 5 during normal operation. I have. The idling operation fuel supply unit 11 is a first fuel supply unit that decompresses and vaporizes high-pressure LPG fuel supplied from a fuel supply source (not shown).
When the pressure in the first decompression chamber 12 reaches a predetermined pressure, the valve closes, and when the pressure in the first decompression chamber 12 becomes lower than the predetermined pressure, the valve opens to reduce the fuel pressure so that the pressure in the first decompression chamber 12 becomes constant. A first opening / closing valve 13 for adjusting the amount of high-pressure LPG fuel supplied from the supply source, and a second opening / closing valve which is opened by an intake negative pressure generated downstream of the throttle valve 3 in the intake passage 2 during idling operation. A valve 14 and a MAS (mixture adjusting screw) 16 which is provided in a fuel passage 15 connecting the fuel passage 8 and the second on-off valve 14 and adjusts an amount of fuel flowing through the fuel passage 15. It is configured.

The fuel supply means 17 during normal operation is provided in parallel with the fuel supply means 11 during idle operation.
A second decompression chamber 18 provided adjacent to the decompression chamber 12 and communicating with the fuel passage 8. The second decompression chamber 18 is opened when an intake negative pressure is generated in the venturi 4. And a third opening / closing valve 19 for supplying the fuel to the fuel nozzle 5. The pressure in the second decompression chamber 18 is adjusted to a pressure substantially equal to the atmospheric pressure.

The slow fuel passage 6 has an intake port 6a having one end opened between the venturi 4 of the intake passage 2 and the throttle valve 3, and an intake port having the other end opened downstream of the fully closed position of the throttle valve 3. An outlet 6b and a throttle valve 3
Is bypassed. The suction port 6b is provided at a position downstream of the other end 3b of the throttle valve 3 in the intake passage 2 when the throttle valve 3 is closed or when the throttle valve 3 is fully opened. The slow fuel passage 6 is provided with fuel adjusting means 6c for adjusting the flow rate of the air-fuel mixture flowing through the passage 6.

The auxiliary fuel passage 7 has one end communicating upstream of the fuel amount correcting means 8a of the fuel passage 8 and the other end divided into an upstream fuel port 7a and a downstream fuel port 7b which will be described later. Respectively, and open to the intake passage 2. The upstream fuel port 7a is located upstream of one end 3a of the throttle valve 3 in the intake passage 2 when the throttle valve 3 is closed, and the throttle valve 3 is opened within an angle of 1 to 5 degrees. It is provided at a position downstream of the one end 3a of the throttle valve 3 in the intake passage 2 when it is turned off. The downstream fuel port 7b is downstream of the upstream fuel port 7a of the auxiliary fuel passage 7 and downstream of one end 3a of the throttle valve 3 of the intake passage 2 when the throttle valve 3 is closed. Is provided. Also, at one end of the auxiliary fuel passage 7,
A throttle portion 7c is provided as a fuel passage hole having a larger flow path resistance than the fuel passage 8.

Here, the fuel supply means 11 during idling operation
The setting of the fuel supply amount and the operation timing of the fuel supply means 17 during normal operation will be described. The idling operation fuel supply means 11 opens the second opening / closing valve 14 by the intake negative pressure generated downstream of the throttle valve 3 in the intake passage 2 during the idling operation, and releases the MAS 16 from the first pressure reducing chamber 12. The fuel is supplied to the fuel passage 8 through the fuel passage 8. At this time, the amount of fuel supplied to the fuel passage 8 is adjusted by the MAS 16.

During normal operation, the fuel supply means 17 supplies fuel to the fuel passage 8 by opening the third on-off valve 19 by the intake negative pressure generated in the venturi 4. The third opening / closing valve 19 is set so as to be opened by the intake negative pressure generated in the venturi 4 when at least the throttle valve 3 is located upstream of the upstream fuel port 7 a of the intake passage 2.

Next, the fuel supply operation of the carburetor 1 will be described. FIG. 1 shows an idle operation state,
The fuel supply during idling will be described. When the engine is started, an intake negative pressure is generated downstream of the throttle valve 3 in the intake passage 2, and the second on-off valve 14 is opened. By opening the second on-off valve 14, the fuel whose amount has been adjusted by the MAS 16 is supplied from the first decompression chamber 12 to the fuel passage 8.

The fuel in the fuel passage 8 is supplied to the fuel amount correcting means 8.
The flow rate is corrected by a and supplied to the intake passage 2 through the fuel nozzle 5. The fuel supplied to the intake passage 2 is mixed with air in the venturi 4 to form an air-fuel mixture, and is supplied to the combustion chamber of the engine through the slow fuel passage 6 as shown by an arrow a. Due to the intake negative pressure generated downstream of the throttle valve 3 in the intake passage 2, the fuel in the fuel passage 8 is supplied to the auxiliary fuel passage 7 through the throttle portion 7 c as shown by an arrow b in the intake passage 2. Air is sucked into the auxiliary fuel passage 7 via the upstream fuel port 7a as shown by an arrow c, and is mixed in the auxiliary fuel passage 7 to form an air-fuel mixture. Supplied to the room. At this time, since the air in the intake passage 2 is sucked into the auxiliary fuel passage 7 via the upstream fuel port 7a, the suction force due to the intake negative pressure is weakened, and the fuel in the fuel passage 8 is sucked into the auxiliary fuel passage 7. The amount is reduced.

During an idling operation, when an accelerator pedal (not shown) is depressed for starting acceleration, as shown in FIG. 2, the throttle valve 3 rotates in the direction of arrow d about the throttle shaft 3c. The throttle valve 3 rotates,
When one end 3a of the throttle valve 3 is opened to a position upstream of the upstream fuel port 7a of the intake passage 2, the intake negative pressure generated downstream of the throttle valve 3 in the intake passage 2 causes the auxiliary fuel passage 7 to be opened. The fuel inside is sucked into the intake passage 2 from the upstream fuel port 7a and the downstream fuel port 7b as shown by an arrow e. Therefore, the vaporizer 10
During the normal operation, the fuel is sucked out from the upstream fuel port 7a and the downstream fuel port 7b until the intake negative pressure required for the operation of the fuel supply means 17 is obtained. The amount of fuel supplied to the engine.

Further, when the accelerator pedal is depressed, the throttle valve 3 is further opened to increase the amount of air flowing through the intake passage 2, so that the intake negative pressure in the venturi 4 increases and the throttle valve in the intake passage 2 is increased. The intake negative pressure generated downstream of the fuel tank 3 is reduced, and the suction of fuel from the upstream fuel port 7a and the downstream fuel port 7b is also reduced. On the other hand, the third on-off valve 19 is in an open state,
The valve is further opened by the rise of the intake negative pressure in the venturi 4, and the fuel in the first decompression chamber 12 is released from the second decompression chamber 18.
The fuel is sucked from the fuel nozzle 5 into the intake passage 2 through the fuel passage 8. The fuel sucked into the intake passage 2 is mixed with air to form an air-fuel mixture and is supplied to the engine. During normal operation, fuel is also supplied to the fuel passage 8 from the idling operation fuel supply means 11.

FIG. 3 shows the result of comparing the fuel supply device of the present invention and the conventional fuel supply device with respect to the concentration of the air-fuel mixture according to the opening degree of the throttle valve at the time of starting. In the figure, the horizontal axis represents the opening of the throttle valve, and the vertical axis represents the concentration of the air-fuel mixture. Further, the characteristics of the fuel supply device of the present invention are indicated by the line A (solid line), and the characteristics of the conventional fuel supply device are indicated by the line B (dashed line).

As can be seen from the comparison result, in the fuel supply device of the present invention, the air-fuel mixture is kept substantially constant during the period from the time of idling operation to the time of normal operation (when the opening of the throttle valve is 0 to 5 degrees). Concentration can be maintained. That is, when shifting from the idling operation at the time of starting or the like to the normal operation, the concentration of the air-fuel mixture is maintained substantially constant, so that the starting acceleration can be performed smoothly. On the other hand, in the conventional fuel supply device, the air-fuel mixture becomes instantaneously thin during the period from the idle operation to the normal operation (when the opening of the throttle valve is 0 to 5 degrees), and the combustion state is unstable. And torque shortage occurs. The characteristic of the fuel supply device of the present invention is that the throttle portion 7c of the auxiliary fuel passage 7 is
Can be adjusted by appropriately setting the effective area, the port opening area of the upstream fuel port 7a and the downstream fuel port 7b, and the like.

[0025]

According to the first and second aspects of the present invention, the fuel supply device is located upstream of the throttle valve with respect to the intake passage when the throttle valve is closed, and An upstream fuel port provided at a position downstream of the throttle valve when the valve is opened at a predetermined angle, and a downstream provided downstream of the throttle valve when the throttle valve is closed with respect to the intake passage. Side fuel port, and an auxiliary fuel passage having one end communicating with the upstream fuel port and the downstream fuel port, and the other end communicating with the fuel passage between the fuel nozzle and both fuel supply means. When the throttle valve in idle operation is closed, fuel is sucked from the fuel passage into the auxiliary fuel passage by the intake negative pressure generated downstream of the throttle valve in the intake passage. Together, are air sucked into the auxiliary fuel passage via the upstream fuel port from the intake passage,
The fuel and air are mixed in the auxiliary fuel passage to form an air-fuel mixture, and the air-fuel mixture is supplied to the engine from the downstream fuel port. The concentration can be maintained, and the vehicle can accelerate smoothly even when it starts and accelerates from the time of idling operation. Also, at the time of start acceleration, when the throttle valve is opened to a position upstream of the upstream fuel port of the intake passage, the intake negative pressure generated downstream of the throttle valve of the intake passage causes the upstream fuel port and the downstream fuel port to be closed. The fuel in the auxiliary fuel passage is sucked out from the side fuel port and the fuel supply means is operated during normal operation to supply fuel from the fuel supply means during normal operation to the fuel passage. Fuel consumption is also improved because there is no need to step on the accelerator.

In the fuel supply device according to the first or second aspect , the negative pressure generated in the auxiliary passage can be switched between a throttle valve opening of 1 to 5 degrees and a throttle valve opening of more than 1 degree . In this case, from idling operation in which the opening of the throttle valve is very small to normal operation, the mixture can be maintained at a substantially constant concentration, the combustion state can be stabilized, and an effect such as the lack of torque can be obtained. .

According to the third aspect of the present invention, even when the auxiliary fuel passage is formed large, a large negative pressure can be applied to the fuel passage by forming the fuel through hole to be small. Can be applied to the fuel passage as a required size.

According to the fourth aspect of the present invention, the negative pressure of the intake passage generated during the idling operation or the normal operation can be applied to the fuel supply source, and the LPG supplied from the fuel supply source according to the operation state. The amount of fuel is adjusted, and a fuel amount corresponding to idle operation or normal operation can be supplied.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel supply device of the present invention.

FIG. 2 is a cross-sectional view of a carburetor illustrating a flow of fuel at the time of starting.

FIG. 3 is a characteristic comparison diagram comparing the fuel supply device of the present invention and a conventional fuel supply device with respect to the concentration of air-fuel mixture according to the opening degree of a throttle valve at the time of starting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carburetor 2 Intake passage 3 Throttle valve 4 Venturi 5 Fuel nozzle 6 Slow fuel passage 7 Auxiliary fuel passage 7a Upstream fuel port 7b Downstream fuel port 7c Throttle portion 8 Fuel passage 10 Vaporizer 11 Fuel supply means at idle operation 17 Normal operation Fuel supply means

Continuation of the front page (56) References Japanese Utility Model Sho 58-152550 (JP, U) Japanese Utility Model Sho 63-1226547 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 21 / 04 F02M 21/06

Claims (4)

(57) [Claims] 1. A throttle valve provided in an intake passage communicating with a combustion chamber of an engine using LPG as a fuel, a venturi provided upstream of the throttle valve in the intake passage and having a fuel nozzle, and an LPG fuel. A fuel passage connecting the fuel nozzle with the fuel supply source that supplies the fuel, an idle operation fuel supply unit that is provided in the fuel passage and supplies fuel to the fuel nozzle during idle operation, and the idle operation fuel supply. A fuel supply device for normal operation, which is provided in parallel with the means and supplies fuel to the fuel nozzles during normal operation. Is also upstream, and at a position downstream from the throttle valve when the throttle valve is opened at a predetermined angle. An upstream fuel port provided in the intake passage; a downstream fuel port provided downstream of the throttle valve when the throttle valve is closed in the intake passage; An auxiliary fuel passage communicating with the downstream fuel port and having the other end communicating with the fuel passage between the fuel nozzle and the fuel supply means. Is set to operate by the intake negative pressure generated in the venturi. 2. The fuel supply device according to claim 1, wherein the upstream fuel port is provided upstream of the auxiliary fuel passage, and the downstream fuel port is provided downstream of the auxiliary fuel passage. 3. The fuel supply device according to claim 1, wherein the auxiliary fuel passage is provided with a fuel passage having a flow passage resistance larger than that of the fuel passage. 4. A pressure reducing valve for reducing and evaporating LPG fuel pressure-fed from the fuel supply source is provided upstream of the fuel supply means during idle operation and the fuel supply means during normal operation in the fuel passage. 4. The fuel supply device according to claim 1, wherein the fuel supply device is provided.