JPH0494443A - Fuel supply device for lpg vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention is directed to
This invention relates to a fuel supply system for PG vehicles.

(Prior Art) Conventionally, this type of fuel supply device for an LPG vehicle has been provided with a fuel supply passage connecting an LPG cylinder and an on-vehicle engine, as shown in, for example, Japanese Utility Model Application Publication No. 1-149557. The engine is equipped with a vaporizer and a mixer, and the vaporizer gasifies the liquefied LPG, and the mixer mixes the LPG with air before supplying it to the combustion chamber of the engine.

By the way, in the fuel supply system for LPG vehicles, LP
Even if the fuel supply passage between the G cylinder and the engine is damaged, for example due to a vehicle collision, this LPG
The flow rate of fuel leaving the cylinder is above a specified level (e.g. 6 liters in terms of water)
An overflow prevention valve that automatically closes and stops fuel from flowing out of the cylinder when the pressure difference between the internal pressure of the cylinder and the line pressure of the fuel supply passage increases to 0-5 kg/cd or more for 17 minutes or more. It is mandatory to provide

(Problems to be Solved by the Invention) However, when there is an overflow prevention valve as described above, the following problem occurs. That is, the LPG fuel filled into an LPG cylinder is generally a mixture of propane and butane, for example, 30% propane and 70% butane.
However, in cold regions and the like, in order to give priority to gasification of the fuel, fuel with a propane composition ratio close to 100% is used. Therefore, when a cylinder is filled with LPG with such a high propane composition ratio in the summer when the outside air temperature is high, the pressure inside the cylinder is high, for example, 16 kg/c-, immediately after filling, but the pressure inside the cylinder is high, for example, 16 kg/c-. The line pressure of the fuel supply passage from the to the engine is 7 to 8 k
g/c becomes low. When the fuel supply passage is opened in this state and the engine is started, a large amount of fuel in the cylinder flows out into the fuel supply passage due to the above pressure difference, creating an operating condition for the overflow prevention valve, which should not operate normally. An overflow prevention valve without a valve malfunctions and closes. As a result, there is a problem in that the engine stops when the fuel in the fuel supply passage runs out some time after the engine is started.

In addition, even if LPG fuel has a normal composition ratio, if the ignition key switch is turned OFF and the vehicle is left in the hot sun in the summer, the above fuel supply may be affected by the atmosphere in the engine room or radiant heat from the road surface. As the line pressure in the passage increases, fuel in the fuel supply passage flows back into the cylinder. After that, when the temperature drops and the line pressure in the fuel supply passage decreases, a large pressure difference occurs between the internal pressure of the cylinder and the line pressure, and if the engine is started in this condition, it will still cause overheating. The flow prevention valve malfunctions.

Furthermore, when the vehicle is stopped and left unattended for a long period of time, by closing the fuel supply passage and operating the engine, all the fuel in the fuel supply passage downstream of the closed part can be drained into the engine. The fuel supply passage may be left empty with no fuel. At this time as well, the line pressure decreases and a pressure difference occurs between the line pressure and the internal pressure of the cylinder, causing the overflow prevention valve to malfunction when the engine is started after being left unused.

The present invention has been made in view of the above points, and its purpose is to provide a fuel supply passage with a predetermined means.
To prevent engine stoppage due to malfunction by avoiding malfunction of an overflow prevention valve under conditions where it is not required to operate without affecting its function.

(Means for solving the problem) In order to achieve this object, the invention of claim (1):
An overflow prevention valve is installed in the fuel supply passage downstream of the overflow prevention valve when fuel flows through the fuel flow passage due to engine startup when there is a large pressure difference between the pressure inside the LPG cylinder and the line pressure of the fuel supply passage. A valve means is provided that automatically closes the valve at a fuel flow rate lower than the valve closing condition, and the valve means throttles the fuel supply passage by closing the valve.

Specifically, in this invention, the fuel supply passage is disposed in a fuel supply passage connecting an LPG cylinder and an on-vehicle engine, and automatically closes when the flow rate of LPG fuel supplied from the LPG cylinder to the engine increases beyond a predetermined level. In a fuel supply system for an LPG vehicle equipped with an overflow prevention valve that closes a fuel supply passage by closing a valve, the fuel supply passage downstream of the overflow prevention valve is closed by an increase in fuel flow rate to open a fuel supply passage. A throttling valve means is provided, and the valve means is configured to close when the flow rate of fuel flowing through the valve means exceeds a set value lower than the closing flow rate of the excess flow prevention valve.

(Function) With the above configuration, in this invention, the valve means that closes at a fuel flow rate lower than the closing flow rate of the overflow prevention valve is disposed in the fuel supply passage downstream of the overflow prevention valve, so that Immediately after filling a cylinder with LPG fuel with a propane composition ratio of approximately 100%, or when the fuel line pressure in the fuel supply passage decreases, the pressure difference between the pressure inside the LPG cylinder and the line pressure in the fuel supply passage may increase. Under severe conditions, when the fuel supply passage is opened by starting the engine, the valve means is closed before the overflow prevention valve operates, and the fuel supply passage is narrowed down to a predetermined passage cross-sectional area. Therefore, the fuel gradually flows through the fuel supply passage restricted by the valve means, and eventually the pressure difference between the internal pressure of the LPG cylinder and the line pressure becomes small, and as a result, the overflow prevention valve is closed. This prevents malfunctions and prevents the engine from stopping.

Further, if the fuel supply passage is damaged due to a vehicle collision or the like and the fuel flow rate from the cylinder to the engine suddenly increases, the overflow prevention valve closes. That is, the role of the overflow prevention valve is utilized as is, and the outflow of fuel from the cylinder is prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 4 shows the overall configuration of an LPG vehicle fuel supply system according to the first embodiment of the present invention, where 1 is an on-vehicle engine, and 2 supplies intake air to a combustion chamber (not shown) in a cylinder of the engine 1. This is an intake pipe, and this intake pipe 2 contains gaseous LPG.
A mixer 3 is provided for mixing the intake air with the intake air.

On the other hand, 4 is an LPG cylinder for storing LPG fuel, and this cylinder 4 and the mixer 3 are connected by a fuel supply passage 5 that supplies the LPG fuel in the cylinder 4 to the engine 1.

A siphon pipe 6 constituting an upstream end portion of the fuel supply passage 5 is supported through the LPG cylinder 4 on the road side thereof, and the lower end (tip) of the siphon pipe 6 opens at the bottom inside the cylinder 4 . As shown in enlarged detail in FIG. 3, the upper end of the siphon pipe 6 is closed by a fuel take-off valve 7 having a built-in overflow prevention valve 15.

This take-out valve 7 has a cylindrical valve case 8 which is curved in a substantially dogleg shape at the middle part, and the siphon pipe 6 of this case 8
A fuel port 9 is opened at the lower end facing inward, and a fuel outlet 10 is opened near the curved portion at the upper side surface. A valve seat 11 is formed within the case 8 and is disposed between the fuel port 9 and the fuel outlet 10 . Further, a valve body 13 having a valve seat 12 that seats on the valve seat 11 and blocks communication between the fuel port 9 and the fuel outlet 10 is slidably inserted into the case 8 , and the valve body 13 is slidably inserted into the upper end of the valve case 8 . The opening is hermetically closed by a spindle 14 that drives the valve body 13 by screwing, and by manually screwing the spindle 14 from the outside, the valve body 13 is driven and the spindle 14 is screwed in. At that time, the valve seat 12 is seated on the valve seat 11 by advancing the valve body 13, and the valve is closed.
When the spindle 14 is returned, the valve body 13 is moved back, and the valve seat 12 is further separated from the valve seat 11 to open the valve.

The overflow prevention valve 15 prevents an overflow condition in which fuel flows out excessively from the LPG cylinder 4, and is disposed at the lower end of the valve case 8 of the take-out valve 7. That is, this excessive flow prevention valve 15 has a rod 1 attached to the lower end of the valve case 8.
It has a disk-shaped valve body 17 that is supported slidably and cannot fall through the valve body 6, and a fuel population 9 is disposed on the upper surface of the valve body 17.
A check seat 19 is provided that can sit on a valve seat 18 formed at the lower end of the surrounding case 8. In addition, the valve body 17
is biased downward by a check seat spring 20 compressed between the valve case 8 and the check seat 19 so as to be a predetermined distance from the valve seat 18. Under normal conditions, the fuel in the siphon pipe 6 is transferred to the valve body. 17, through the gap between the check sheet 19 and the valve seat 18, into the fuel population 9,
The amount of inflow, that is, the amount of fuel flowing out from the LPG cylinder 4 is at least a predetermined value (61/min or more in terms of water, or the pressure difference between the internal pressure of the cylinder 4 and the line pressure of the fuel supply passage 5 is 0.5k).
g/cd or higher), the upward force of the fuel against the valve body 17 increases, causing the valve body 17 to move upward against the urging force of the check seat spring 20, and the check seat 19 to be seated on the valve seat 18. By this, excessive flow prevention valve 1
5 in a closed state. Note that, in FIG. 3, a passage connecting the fuel outlet 9 and the outlet 10 at the lower end of the valve case 8 is omitted.

Further, a return #1 structure 21 is provided in the valve case 8 to return the excessive flow prevention valve 15 from the closed state. This return mechanism 21 has a bushing rod 22 that is slidably supported at the lower part of the valve case 8, and this bushing rod 22 is urged upwardly by a spring 23, and in this state, the valve body 17 of the excessive flow prevention valve 15 Rod 1 when check sheet 19 is seated on valve seat 18
6. It is possible to make contact with the upper end. On the other hand, a cancel bin 24 capable of suppressing the upper end of the bushing rod 22 is integrally attached to the valve body 13 of the take-out valve 7, and a check seat 19 of the valve body 17 is seated on the valve seat 18 to prevent excessive flow. When the spindle 14 is moved forward to close the take-out valve 7 while the valve 15 is in the closed state, the forward movement of the cancel bin 24 pushes down the valve body 17 of the overflow prevention valve 15 via the bushing rod 22 to open the valve. I'm trying to get it back to .

The fuel outlet 10 of the take-out valve 7 is connected to an emergency shutoff valve 26 via a pipe 25. The emergency shutoff valve 26 shuts off the fuel supply passage 5 when the engine 1 stops, and is provided integrally with a filter device 32 that filters fuel. That is, as shown in FIG. 3, the emergency shutoff valve 26 includes a valve case 29 in which a fuel port 27 and a fuel outlet 28 are opened.
9 has a first opening 30 communicating with the fuel port 27.
and a second opening 31 that communicates with the fuel outlet 28 via third and fourth openings 39 and 40, which will be described later. The lower surface of the valve case 29 is airtightly covered by a cup-shaped filter case 33 that constitutes a part of the filter gW132, and the space inside this filter case 33 is formed into an outer chamber communicating with the first opening 30 by a cylindrical filter 34. 35 and an inner chamber 36 that communicates with the second opening 31. The inner chamber 36 is provided with a permanent magnet 37 that is screwed and supported by the second opening 31. inner chamber 36
A communication hole 38 is formed to communicate with the two. When the fuel flows from the outer chamber 35 to the inner chamber 36, it is filtered by a filter 34 and magnetic impurities in the fuel are removed by a magnet 3.
7, it is adsorbed and removed.

Further, on the upper surface of the valve case 33, a third opening 39 communicating with the second opening 31 and a fourth opening 39 communicating with the fuel outlet 28 are provided.
An opening 40 is open, and a valve seat 41 is formed around the fourth opening 40 .

The upper surface of the valve case 33 has a valve body storage chamber 42 in the center of the lower surface.
A valve body 44 that can be seated on the valve seat 41 is slidably supported in the valve body housing chamber 42 of the valve body support part 43 . A return spring 45 is installed between the valve body 44 and the bottom surface of the valve body housing chamber 42, and this spring 45 biases the valve body 44 to close and seat it on the valve seat 41. .

A solenoid 46 is arranged in the valve body support portion 43 so as to surround the valve body housing chamber 42 .
The valve body 44 is attracted upward against the biasing force of the return spring 45 and separated from the valve seat 41 by excitation caused by energization, thereby opening the valve.

As shown in FIG. 4, a solenoid valve 47 and a vaporizer 48 are arranged in the fuel supply passage 5 between the emergency shutoff valve 26 and the mixer 3 in this order from the upstream side (the cylinder 4 side). The solenoid valve 47 is connected to the fuel supply passage 5
The emergency shutoff valve 26 has the same structure as the emergency shutoff valve 26, and detailed explanation thereof will be omitted here. On the other hand, the vaporizer 48 evaporates the liquefied fuel into gaseous fuel, and the gaseous fuel generated here is supplied to the mixer 3 via a gas pipe 49.

Further, as a feature of the present invention, on the downstream side of the overflow prevention valve 15, the emergency cutoff valve 26 and the solenoid valve 4
A malfunction control valve 50 that closes and throttles the fuel supply passage 5 when the fuel flow rate reaches a set value is disposed in the fuel supply passage 5 between the fuel supply passage 5 and the fuel supply passage 5 . This malfunction control valve 50
The set value of the fuel flow rate when the valve closes is a value lower than the valve closing flow rate of the overflow prevention valve 15 (1.8 to 265 in terms of water).
1/min or more, or the pressure difference between the internal pressure of the cylinder 4 and the line pressure of the fuel supply passage 5 is set to 0.25 kg/cd or more). The malfunction control valve 50 is the overflow prevention valve 15.
It has a similar structure. That is, the malfunction control valve 50 is, as shown in enlarged detail in FIG.
A cylindrical valve case 51 is screwed onto the fuel outlet 28 of the valve case 29 of No. 6, and a part of the fuel supply passage 5 is formed inside the case 51.

A valve chamber 52 is formed in a longitudinally intermediate portion of the valve case 51, and a ring-shaped valve seat 53 protrudes from the valve chamber 52. The valve chamber 52 is provided with a disk-shaped valve body 54 that can be seated on the valve seat 53 on the lower surface, and this valve body 54 is connected to the rod 5.
5 so as to be slidable in the vertical direction. Also,
A return spring 56 is compressed between the valve body 54 and the valve case 51 and is positioned around the rod 55 and biases the valve body 54 in the valve opening direction (away from the valve seat). When the amount of fuel flowing out from the LPG cylinder 4 increases and exceeds a set value lower than the closing flow rate of the overflow prevention valve 15, an increase in the pushing force of the fuel valve body 54 causes the valve body 54 to spring. The overflow prevention valve 15 is closed by moving it downward against the urging force of the valve 56 and seating it on the valve seat 53.

Furthermore, as shown in FIG. 2, the ring-shaped valve seat 53
have a plurality of V-shaped grooves 57, 57., each having a V-shaped cross section, a portion of which is cut out in the radial direction. ... is formed, and when the malfunction control valve 50 is closed, the fuel supply passage 5 is not completely closed, and the gap between the valve body 54 and each V-groove 57 of the valve seat 53 is closed. By allowing a predetermined amount of fuel to flow through the fuel supply passage 5, the fuel supply passage 5 is narrowed down to a predetermined cross-sectional area.

Therefore, in the above embodiment, when the engine 1 is started, the emergency shutoff valve 26 and the solenoid valve 47 are opened to open the fuel supply passage 5, and the liquid LPG fuel in the LPG cylinder 4 flows through the fuel supply passage 5. Vaporizer 4
The LPG is supplied to the engine 8 and gasified, and after being mixed with intake air in the mixer 3, the LPG is supplied to the engine 1.

In this case, for example, in the summer, the propane composition ratio is approximately 100%.
Immediately after filling the LPG cylinder 4 with fuel, or due to backflow of fuel in the fuel supply passage 5 into the cylinder 4, the LP
When the pressure difference between the pressure in the G cylinder 4 and the line pressure in the fuel supply passage 5 is large, when the emergency shutoff valve 26 and the solenoid valve 47 are opened by starting the engine 1, a large amount of fuel in the cylinder 4 is released. It flows out into the supply passage 5, and due to the increase in flow rate, the overflow prevention valve 15 attempts to close.

However, the fuel supply passage 5 immediately downstream of the emergency shutoff valve 26
A malfunction control valve 50 is disposed in the valve 50.
Since the set value of the fuel flow rate for closing the valve is lower than that of the overflow prevention valve 15, the malfunction control valve 50 closes before the overflow prevention valve 15 attempts to close, and this valve closes. The gap between the valve body 54 of the malfunction control valve 50 and each V-groove 57 of the valve seat 53 narrows the fuel supply passage 5 to a predetermined passage cross-sectional area. Since fuel gradually flows through the fuel supply passage 5 which is throttled by the malfunction control valve 5o, the above-mentioned L
The pressure difference between the internal pressure of the PG cylinder 4 and the line pressure gradually decreases. As a result, even if there is a pressure difference between the internal pressure of the LPG cylinder 4 and the line pressure, the fuel flow rate will not increase to the closing flow rate of the overflow prevention valve 15, and the malfunction of the overflow prevention valve 15 will be prevented and the engine 1 can be effectively prevented from stopping.

In addition, the fuel supply passage 5 may be damaged due to a vehicle collision, etc.
When the fuel flow rate suddenly reaches the closing flow rate of the overflow prevention valve 15, the overflow prevention valve 15 closes, the fuel supply passage 5 is closed, and the outflow of fuel from the LPG cylinder 4 is prevented. In this way, the role of the excessive flow prevention valve 15 can be utilized as is.

5 and 6 show a second embodiment; the same parts as in FIGS. 1 and 3 are denoted by the same reference numerals and detailed explanation thereof is omitted), a malfunction control valve 50' is provided in the filter device 32 upstream of the emergency shutoff valve 26.

That is, in this embodiment, the permanent magnet 37' of the filter device 32 is used as a valve case of the malfunction control valve 50', and the magnet 37' has a valve chamber 52 in its communication hole 38'.
' is formed, a valve seat 53' protrudes from this valve chamber 52', and this valve seat 53' has a plurality of V grooves 57.
57. ... is formed. Also, in the valve chamber 52', a valve body 5, which is a spherical body that seats on the valve seat 53' and closes the valve, is provided.
4', and a return spring 56 that biases the valve body 54' in the valve opening direction (downward). Under normal conditions, the biasing force of the return spring 56 causes the valve body to
4' is removed from the valve seat 53' to open the valve, while
When the amount of fuel flowing out from the LPG cylinder 4 increases and exceeds a set value lower than the closing flow rate of the excessive flow prevention valve 15, the force of pushing up the fuel against the valve element 54' increases, causing the valve element 54 to
' is moved upward against the biasing force of the spring 56 and seated on the valve seat 53', thereby closing the overflow prevention valve 15 and closing the V between the valve body 54' and the valve seat 53'. Groove 57
, 57. ... to narrow down the fuel supply passage 5.

Therefore, this embodiment can also provide the same effects as the first embodiment.

Further, since the malfunction control valve 50' is disposed within the filter device 32 of the emergency shutoff valve 26, there is an advantage that the entire fuel supply system can be made compact.

(Effect of the invention) As explained above, according to the invention of claim (1), L
In the fuel supply system of a PG vehicle, a valve is installed in the fuel supply passage downstream of the overflow prevention valve to close the fuel supply passage when the fuel flow rate exceeds a set value lower than the closing flow rate of the overflow prevention valve. By providing a throttling valve means, even when the engine is started under conditions where there is a large pressure difference between the internal pressure of the LPG cylinder and the line pressure of the fuel supply passage, the function of the overflow prevention valve can be utilized and its malfunction can be prevented. This can prevent the engine from stopping.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is an enlarged cross-sectional view of the malfunction control valve, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. FIG. 4 is an enlarged cross-sectional view showing the main parts of the fuel supply device, and FIG. 4 is a front view of the entire same. 5 and 6 show a second embodiment, in which FIG. 5 is an enlarged sectional view of the main part of the malfunction control valve, and FIG. 6 is a sectional view of the emergency shutoff valve. 1...Engine 3...Mixer 4...LPG cylinder 5...Fuel supply passage 7...Fuel take-off valve 15...Overflow prevention valve 17...Valve body 18...Valve seat 26...Emergency shutoff valve 32...Filter device 50.50'...Malfunction control valve (valve means) 53.
53'...Valve seat 54.54'...Valve body 57...■Groove 1...Engine 3...Mixer 4...LPG cylinder 5...Fuel supply passage 7...Fuel Take-out valve 15... Overflow prevention valve 17... Valve body 32... Filter device 50, 50'... Malfunction control valve 53, 53'
... Valve seat 54, 54'... Valve body 57... V groove (valve means) Fig. 1

Claims (1)

[Claims] (1) The valve is installed in the fuel supply passage that connects the LPG cylinder and the on-vehicle engine, and automatically closes when the flow rate of LPG fuel supplied from the LPG cylinder to the engine increases above a predetermined value. In a fuel supply system for an LPG vehicle equipped with an overflow prevention valve that closes the overflow prevention valve, a valve means is disposed in the fuel supply passage downstream of the overflow prevention valve to close and throttle the fuel supply passage when the fuel flow rate increases. and the valve means is configured to close when the flow rate of fuel flowing through the valve means exceeds a set value lower than the closing flow rate of the overflow prevention valve. fuel supply system.