JPS5911740B2 - LP - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an LP gas engine, and in particular to a fuel supply system for an LP gas engine that is improved in view of the fact that a large amount of unburned gas is released into the exhaust system during first gear. Related.

Similar to gasoline engines, in LP gas engines, incomplete combustion and misfires occur due to a decrease in the volumetric efficiency of the engine during long decelerations (in this case, deceleration operation for about 2 seconds or more) such as when driving downhill. However, a large amount of unburned gas is released into the exhaust system, which not only causes deterioration of exhaust gas characteristics (but also, in the case of a vehicle equipped with an aftertreatment device such as a catalytic converter, a large amount of unburned gas in the aftertreatment device) This can lead to problems such as rapid thermal reactions due to fuel entering the system and overheating of the after-treatment equipment.

On the other hand, an LP gas engine is equipped with a regulator that vaporizes the LP gas stored in liquid form under reduced pressure 1, adjusts the pressure of the vaporized LP gas, and supplies it to the carburetor. As a safety mechanism to prevent fuel from flowing out when the engine is stopped, it is equipped with a valve device that is supplied with intake pipe negative pressure as control fluid pressure and closes to cut off the flow of fuel when the intake pipe negative pressure is below a predetermined level.

Therefore, the present invention utilizes the valve device included in the above-mentioned LP gas engine regulator to avoid complicating the fuel supply system (when the engine is decelerating, etc., the fuel supply to the engine is cut off). It is an object of the present invention to provide a fuel supply system for an LP gas engine that can avoid an increase in unburnt gas in exhaust gas during engine deceleration and can also prevent overheating of an aftertreatment device.

According to the present invention, the present invention has a pressure regulating structure that regulates and supplies the supplied LP gas to a predetermined pressure, and an intake pipe negative pressure that is supplied as a control fluid pressure when the intake pipe negative pressure is below a predetermined level. A regulator for an LP gas engine is provided with a valve structure that closes and stops the supply of LP gas; This is achieved by a fuel supply system for an LP gas engine characterized by including a switching valve device that supplies atmospheric pressure or positive pressure to the valve structure instead of the negative pressure in the intake pipe.

According to the configuration described above, when the throttle valve is closed during deceleration, the intake pipe negative pressure increases, and when it reaches a predetermined high level or higher, the switching valve device switches and operates to supply the control fluid to the valve device. By supplying atmospheric pressure or positive pressure instead of the intake pipe negative pressure as the pressure, the valve device becomes a closed state regardless of the intake pipe negative pressure at that time, and the supply of fuel to the engine is cut off.

As a result, during deceleration, unburned gas is prevented from being released into the exhaust system, and fuel efficiency is improved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a somewhat exploded sectional view showing an example of a fuel supply system for an LP gas engine according to the present invention.

In the figure, reference numeral 1 generally indicates a casing of an LP gas engine regulator equipped with a primary slow system, and the casing 1 has a first sealed structure on both sides of the casing 1, which is separated by a central partition wall 2. Room 3 and second room 4 are defined.

The first chamber 3 is divided into a primary pressure reduction chamber 6 and a primary pressure regulation chamber 7 by a first diaphragm 5. Among these, the primary pressure reduction chamber 6 has an LP gas inflow path 8 opened, and the LP gas inflow path 8 is opened to the primary pressure reduction chamber 6. A first pulp lever 11 swingably supported on a shaft 10 is provided to open and close the opening, that is, the primary inflow port 9.

The liquid LP gas that has flowed into the LP gas inflow path 8 pushes the first pulp lever 11 with its own pressure, pushes open the primary inflow port 9, enters the primary decompression chamber 6, and is vaporized under reduced pressure.

When the pressure inside the decompression chamber 6 reaches a predetermined pressure, the first diaphragm 5 is biased to the left in the figure against the action of the first regulator spring 120 provided in the primary pressure regulation chamber 7, and the first diaphragm hook 13 The first valve lever 11 is biased toward the closing side to close the primary inflow port 9, and when the pressure inside the primary decompression chamber 6 decreases due to fuel consumption, the first pulp lever 11 is biased toward the opening side and the primary inflow port 9 is opened. , fuel is caused to flow into the primary decompression chamber 6 from the LP gas inflow path 8 .

In this manner, the first pulp lever 11 maintains the pressure within the primary decompression chamber 6 at a predetermined constant value by repeatedly opening and closing the primary inflow port 9.

The second chamber 4 is divided by a seven-cant diaphragm 14 into a secondary pressure reduction chamber 15 and a secondary pressure regulation chamber 16, of which the secondary pressure reduction chamber 15 has a passage 17 penetrating the central partition wall 2 of the casing 1. It communicates with the human decompression chamber 6, and is connected to a capretor (not shown) through a main fuel take-out port 18 opening into the secondary decompression chamber 15 and a main fuel passage 19 connected thereto. pressure is being exerted.

Inside the secondary decompression chamber 15 is an end of the passage 17 on the side of the secondary decompression chamber, that is, a secondary inflow port 20 (supported by a shaft 21 and always biased toward the closing side by the action of a second regulator spring 220). A second valve lever 23 is provided.

This second valve lever 23 is caused by the second diaphragm 14 being biased to the left in the figure by the venturi negative pressure exerted in the secondary decompression chamber 15, so that the pusher 24
is biased toward the opening side (clockwise in the figure) through the passage 17 to open the secondary inflow port 20, and is biased toward the closing side by the action of the second regulator spring 220, while the secondary pressure reduction is caused by the passage 17. It functions to reduce the pressure of the fuel introduced into the chamber 15 to approximately atmospheric pressure and maintain it at a constant pressure.

Fuel at approximately atmospheric pressure in the secondary decompression chamber 15 is delivered to the capretor via the main fuel take-out port 18 and the main passage 19 by venturi negative pressure.

A main lock chamber 26 defined by the central partition wall 2 of the casing 1 and the main lock diaphragm 25 is defined within the secondary decompression chamber 15. lock diaphragm 2
Main lock spring 2 that biases 5 to the right in the diagram.
7 is provided, and intake pipe negative pressure is applied from the intake pipe negative pressure passage 28.

That is, when the engine is stopped and the intake pipe negative pressure is substantially zero, the main lock diaphragm 25 is biased to the right in the figure by the action of the main lock spring 260, and the second The main lock spring 270 biases the valve lever 23 toward the closing side and prevents it from biasing toward the opening side.In contrast, when substantial intake pipe negative pressure is applied to the main lock chamber 26 during engine operation, the main lock spring 270 The second valve lever 23 is biased to the left in the figure against the action, and is configured to allow the second valve lever 23 to bias toward the opening side.

Further, one end of a slow fuel passage 31 is opened in the igneous pressure chamber 6 and communicates with a carburetor (not shown) via a slow passage 30.

An idle just screw 32 for adjusting the flow rate of the slow fuel passage 31 is provided in the middle of the slow fuel passage 31, and a spool valve type slow lock valve 33 for opening and closing the fuel passage is provided.

The slow lock valve 33 has a flange provided at one end to actually open and close the opening of the slow fuel passage 31 to the primary decompression chamber 6, that is, the slow fuel outflow port 34, and the other end is connected to the casing 1. A slow lock diaphragm 3BK'ff3 is provided which cooperates with the central partition wall 2 to define a slow lock chamber 35.

The slow-lock diaphragm 36 is biased to the right in the figure by the action of a slow-lock spring 370 provided in the slow-lock chamber 35, biasing the slow-lock valve 33 toward the closing side, and the intake pipe negative pressure passage 28. When a predetermined intake pipe negative pressure is applied to the slow lock chamber 35 through the main lock chamber 26 and the passage 38, the slow lock valve 33 is biased to the left in the figure against the action of the main lock spring. is biased toward the open side.

That is, the slow lock valve 33 is opened when a predetermined intake pipe negative pressure is generated by cranking when the engine is started, and when a predetermined intake pipe negative pressure is generated during idling. The fuel inside is supplied to the carburetor through the slow passage 30 under positive pressure.

The secondary pressure regulating chamber 7 is communicated with the secondary pressure reducing chamber 15 through a passage (not shown), and the secondary pressure regulating chamber 16 is connected to the port 1.
6a is open to the atmosphere.

According to the present invention, a switching valve device generally indicated by reference numeral 39 is provided in the middle of the intake pipe negative pressure supply system to the intake pipe negative pressure passage 28.

This switching valve device 39 includes an intake pipe negative pressure port 41 to which a conduit 40 is connected and to which intake pipe negative pressure is supplied, and an atmospheric port 42.
and a port 43 which is connected to the intake pipe negative pressure passage 2B by the diameter of the conduit 44, and the port 43 is selectively connected to either the intake pipe negative pressure port 41 or the atmospheric port 42 (Fig. a diaphragm 46 supporting one end of the valve body 45; and a diaphragm chamber into which intake pipe negative pressure is introduced from a port 48 defined above the diaphragm 46. 47, and a compression coil spring 49 that biases the diaphragm 46 downward in the figure, and the valve body 45 is normally in a downward switching position due to the action of the compression coil spring 49, thereby reducing intake pipe negative pressure. The ports 41 and 43 are connected, and when a predetermined high level of intake pipe negative pressure is introduced into the diaphragm chamber 47 during deceleration, etc., the valve is moved upwardly to the switching position against the action of the compression coil spring 490. The biased port 43 is connected to the atmospheric port 42 instead of the intake pipe negative pressure port 41.

Therefore, when the intake pipe negative pressure does not reach a predetermined high level during deceleration (engine braking), etc. during normal driving or idling, the switching valve 390 valve body 45 switches downward. position to maintain communication between the intake pipe negative pressure port 41 and the port 43, and the main lock chamber 26 and the intake pipe negative pressure port 41, the port 43, the conduit 44, and the intake pipe negative pressure port 41, the intake pipe negative pressure port 43, the intake pipe 44, and Intake pipe negative pressure is introduced via the pipe negative pressure passage 28 and the passage 38 .

Therefore, in such a state, the main lock diaphragms 2 and 5 are biased to the left in the figure, allowing the second valve lever 23 to bias toward the opening side, and the second pulp lever 23 is biased toward the venturi negative side. It is opened and closed depending on the pressure, and fuel is supplied from the main passage 19.

Further, when the negative pressure in the intake pipe led to the slow lock chamber 35 reaches a predetermined level, the slow lock valve 33 is opened and fuel is supplied from the slow passage 30.

When the engine decelerates during long downhill driving and the intake pipe negative pressure reaches a predetermined high level, the switching valve 3
The diaphragm 46 of No. 9 is biased upward together with the valve body 45, thereby connecting the port 43 with the atmospheric port 42 instead of the intake pipe negative pressure port 40.

Therefore, the main lock chamber 26 and the slow lock chamber 35 have substantially atmospheric pressure, and the main lock diaphragm 25
and the slow lock diaphragm 36 are each biased to the right in the figure by the action of the lock spring 27°37,
Second pulp lever 23 and slow lock valve 33
are forcibly biased toward the closing side regardless of the throttle negative pressure and intake pipe negative pressure at that time, and the supply of fuel from each of the main passage 19 and the slow passage 30 is forcibly cut off.

Therefore, since no fuel is supplied to the engine during deceleration, unburned fuel is prevented from being released into the exhaust gas.

Note that the switching valve 39 is not limited to the structure as in the embodiment described above (for example, it can also be achieved by a combination of a negative pressure switch valve 50 and an electromagnetic switching valve 51 as shown in FIG. be done.

In this case, the negative pressure switch valve 50 is connected to the diaphragm chamber 52.
When a predetermined high level of intake pipe negative pressure is applied to the diaphragm 53, the electric contact 54.
55 may be a negative pressure switch valve known per se, including a valve body 56 such as that electrically connected to the valve body 55.

The electromagnetic switching valve 51 also includes a solenoid element 57 that is energized in response to electrical connection of the electrical contacts 54 and 55 of the negative pressure switch valve 50, and a solenoid element 57 that is biased downward in the figure by the energization of the solenoid element 57. When the solenoid element 57 is demagnetized and the valve body 58 is in the upper switching position, the port 59 is connected to the intake pipe negative pressure port 61. It's fine if it's from.

In this case, the port 59 of the electromagnetic switching valve 51 is connected to the intake pipe negative pressure passage 28 of the generator described above via the conduit 44, and the intake pipe negative pressure intake port 61 is connected to the conduit 40.

Furthermore, in the above embodiment, the fuel supply to both the slow system and the main system is cut off when the deceleration special intake pipe negative pressure reaches a predetermined high level, but this depends on the engine characteristics. The fuel supply from either the main system or the slow system may be cut off depending on the situation (and, of course, the present invention can also be implemented in a regulator that does not include a primary slow system).

In addition, in the above-mentioned embodiment, when the intake pipe negative pressure reached a high level, the lock chamber was connected to the atmospheric port to be opened to the atmosphere, but instead of the atmospheric port, the lock chamber was connected to the atmospheric port and was connected to the secondary air supply pump. Positive pressure air may be introduced into the lock chamber by connecting to the air supply path of the lock chamber, thereby positively biasing the lock diaphragm toward the valve closing side.

[Brief explanation of the drawing]

FIG. 1 is a somewhat exploded sectional view showing an embodiment of the fuel supply system for an LP gas engine according to the present invention, and FIG. 2 is a sectional view of a switching valve device used in the fuel supply system for an LP gas engine according to the present invention. FIG. 7 is a sectional view showing another embodiment in a somewhat exploded manner. 1 - Regulator casing, 2 - central bulkhead, 3 -
1st chamber, 4-second chamber, 5-first diaphragm, 6-second pressure reduction chamber, 7-second pressure adjustment chamber, 8-LP gas inflow path, 9-primary inflow port), 10-shaft , 11~first pulp lever, 12~first resistor link, 13~first diaphragm hook, 14~
Second diaphragm, 15 - secondary pressure reduction chamber, 16 - secondary pressure regulation chamber, 16a - port, 17 - passage, 18 - main fuel extraction port, 19 - main passage, 20 - secondary inflow port, 21 - shaft, 22 ~Second regulator toss ring, 23~Second valve lever, 24~Oshioji, 25
~Main lock diaphragm, 26~Main lock chamber,
27-Main lock spring, 28-Intake negative pressure passage, 29-Press element, 30-Slo one passage, 31-Slow fuel passage, 32-Idle adjust screw, 33-Slow lock pulse 7', 34-Slow 1e fee outflow ho), 3
5~Slow lock chamber, 36~Slow lock diaphragm, 37~Slow lock spring, 38~Passway, 39~
Switching valve device, 40 - conduit, 41 - intake pipe negative pressure port, 4
2 - atmospheric port, 43 - conduit, 44 - port, 45 - valve body, 46 - diaphragm, 47 - diaphragm rigid, 48
~ Port, 49 ~ Compression coil spring, 50 ~ Negative pressure switch valve, 51 ~ Solenoid switching valve, 52 ~ Diaphragm chamber,
53 - diaphragm, 54. 55 - electrical contact, 56 - valve element, 57 - renoid element, 58 - valve element, 59 - port, 60 - atmosphere port, 61 - intake pipe negative pressure port.

Claims (1)

[Claims] 1. A pressure regulating structure that regulates and supplies the supplied LP gas to a predetermined pressure, and the intake pipe negative pressure is supplied as a control fluid pressure, and when the intake pipe negative pressure is below a predetermined level, it becomes a closed state and supplies LP gas. An LP gas engine regnumter is equipped with a valve structure that stops the intake pipe negative pressure during deceleration (when the intake pipe negative pressure exceeds a predetermined high level, the control fluid pressure is replaced with a large intake pipe negative pressure). A fuel supply system for an LP gas engine, comprising a switching valve device that supplies atmospheric pressure or positive pressure to the valve structure.