JPH0221586Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a regulator for an LPG engine.

Conventional technology LPG (liquefied petroleum gas) has traditionally been used as a fuel for automobiles, especially for commercial vehicles such as taxis.
is used. LPG is composed of a mixed gas of propane, propylene, butane, butylene, etc., which is compressed to about 1/250 of its gaseous state and turned into a liquid at room temperature and sealed in a cylinder. like this
In LPG engines that use LPG as fuel, LPG stored in liquid form is vaporized under reduced pressure.
The pressure of the vaporized LPG is adjusted and a mixer is used.
It is equipped with a regulator that supplies the

The regulator is filled with liquid LPG, which is normally stored in a cylinder at a pressure of 2 to 8 Kg/cm ^2, at a pressure of approximately 0.3 Kg/cm ^{2 .}
The primary decompression chamber reduces the pressure to
It is equipped with a secondary decompression chamber that reduces the pressure of LPG to about atmospheric pressure and supplies it to the mixer. The primary pressure reduction chamber and the secondary pressure reduction chamber are each separated from the pressure regulation chamber by a diaphragm, and atmospheric pressure is normally introduced into the pressure regulation chamber of the secondary pressure reduction chamber. A secondary valve is provided in the passage that communicates the primary decompression chamber and the secondary decompression chamber, and this secondary valve opens against the spring force provided in the secondary decompression chamber during engine operation to prevent the mixer from flowing. It is designed to supply fuel to the bench lily section. Further, the primary decompression chamber is provided with a slow fuel outlet opening downward from a passage communicating the primary decompression chamber and the secondary decompression chamber. The slow fuel outlet is connected to the bench lily of the mixer through a slow fuel passage, and the slow fuel passage is generally provided with a slow lock valve. This slow lock valve is opened when a predetermined intake pipe negative pressure is generated due to cranking when the engine is started, or when a predetermined intake pipe negative pressure is generated during idling, and the fuel in the primary decompression chamber is turned into slow fuel. Positive pressure is supplied to the mixer through the passage.

Problems that the invention aims to solve As mentioned above, LPG is made of propane, propylene,
It is composed of a mixed gas of butane, butylene, etc., but it is mainly a mixture of propane and butane, and the mixing ratio varies depending on the region, season, etc.
For example, if we use LPG with 20% propane and 80% butane and start the engine when the engine temperature is equal to the outside temperature, that is, when the engine is cold, the fuel pressure in the cylinder when the outside temperature is 20°C is Approximately from the diagram
It is 3.1Kg/ ^cm2 . LPG stored in a cylinder is first supplied to the preheater chamber of the regulator, but
Since the fuel pressure in the preheater chamber is the same as the fuel pressure in the cylinder, there is no difference between the fuel temperature and the temperature in the preheater chamber until the cooling water warms up, and LPG does not vaporize. When the primary valve is opened and the fuel enters the primary decompression chamber, the fuel pressure will be approximately 0.3Kg/ ^cm2 , so the fuel liquid temperature will be approximately -
The temperature drops to 11°C (see Figure 3). Therefore, a temperature difference of 30°C or more is created between the temperature of the primary decompression chamber (20°C) and the fuel temperature, and the LPG absorbs heat from the wall of the primary decompression chamber and is sufficiently vaporized.

However, when the outside temperature is low, fuel cannot be sufficiently vaporized in the primary decompression chamber. for example,
When the outside temperature is 2°C, the fuel pressure in the cylinder is approximately 1.2 kg/cm ² from the graph in Figure 3. As mentioned above, fuel is not vaporized in the preheater chamber, and when it enters the primary depressurization chamber, the fuel pressure is reduced to approximately 0.3Kg/ ^cm2 , so
The fuel liquid temperature drops to about -11°C. Since the temperature of the primary decompression chamber is 2°C, there is only a 13°C temperature difference from the liquid temperature of the fuel, which reduces the amount of heat transfer, and therefore the fuel is not sufficiently vaporized in the primary decompression chamber. For this reason, liquid accumulates in the primary decompression chamber, and if the liquid accumulates up to the slow fuel outlet, liquid fuel will be supplied to the mixer from the slow fuel passage, causing the air-fuel ratio to become overrich, which may cause an engine stall. be. In this way, low-pressure water with a high butane content
When using LPG, there was a problem in which the engine stalled during first idle and was difficult to restart.

In order to solve this problem, an LPG engine regulator has been proposed in which the slow fuel outlet is located higher than the passage entrance to the secondary decompression chamber. According to the structure of this regulator, when liquid accumulates in the primary decompression chamber and the liquid level reaches the communication path to the secondary decompression chamber, the liquid flows to the secondary decompression chamber.
When liquid flows into the secondary decompression chamber and accumulates, the pressure of the gas in the secondary decompression chamber decreases due to the liquid pressure due to the weight of the liquid, and the differential pressure with the mixer bench lily decreases and the gas is supplied. There is a problem that the amount of main fuel decreases and the mixture becomes lean.

Therefore, the purpose of the present invention is to overcome the drawbacks of the conventional regulator described above, and to provide an LPG regulator that always maintains an optimal air-fuel ratio during first idle and prevents engine stall due to insufficient vaporization of LPG at low temperatures.
An object of the present invention is to provide a regulator for an engine.

Means for solving the problems In order to solve the problems of the above-mentioned conventional technology,
The present invention includes a primary decompression chamber, a secondary decompression chamber, and a communication passage that communicates these two decompression chambers, and the secondary decompression chamber is connected to a mixer via a fuel passage to transfer the supplied LPG to the first decompression chamber. In a regulator for an LPG engine, the pressure is regulated to a predetermined pressure by a secondary pressure reduction chamber and a secondary pressure reduction chamber and supplied to the mixer,
The primary decompression chamber is provided with a first slow fuel outlet that opens above the communication passage and a second slow fuel outlet that opens below the communication passage,
The present invention provides a regulator for an LPG engine, characterized in that these first and second slow fuel outlets are connected to the mixer via a slow fuel passage.

Effect When starting the engine when the outside temperature is low, LPG is not sufficiently vaporized in the primary decompression chamber, and liquid accumulates in the primary decompression chamber. Liquid level is 1
When the chamber rises to the position of the passage communicating the primary decompression chamber and the secondary decompression chamber, liquid LPG is supplied from the primary decompression chamber to the secondary decompression chamber. In such a case, according to the present invention, liquid is discharged from the second slow fuel outlet.
LPG is taken out, vaporized LPG is taken out from the first slow fuel outlet, and both are mixed and supplied to the mixer via the slow fuel passage. That is, during first idle when the outside temperature is low, two slow fuel intake ports are provided that open to the primary decompression chamber, and liquid LPG is taken out from one and vaporized LPG is taken out from the other and supplied to the mixer. Therefore, it is possible to prevent the air-fuel ratio from becoming overrich or overlean at low temperatures, and it is possible to maintain a good fast idle at low temperatures.

Embodiment Hereinafter, the present invention will be described in detail based on one embodiment with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a regulator for an LPG engine according to the present invention. 1 generally shows a casing of a regulator for an LPG engine, and the casing 1 has a first chamber 3 and a second chamber 4 of a sealed structure on both sides of the central partition wall 2.
is defined. The first chamber 3 is separated by a first diaphragm 5 into a primary pressure reduction chamber 6 and a primary pressure regulation chamber 7, and a preheater chamber adjacent to the primary pressure reduction chamber 6 is formed by a central partition wall 2 and a partition wall 8. 40 are provided. The preheater chamber 40 has an LPG inflow path 9
is open. The primary valve 11 is the primary inflow port 10 between the preheater chamber 40 and the primary decompression chamber 6.
It is provided to open and close.

The first diaphragm 5 has a primary valve lever 1
2, a hook 13, and a pressing member 14 are screwed together, and the primary valve 11 is opened and closed by these members. A first spring 15 is interposed between the first diaphragm 5 and the retainer 16 in the primary pressure regulating chamber 7, and this first spring 15 biases the first diaphragm 5 in the right direction. . 17 is an adjustment screw, and by adjusting this adjustment screw, the spring pressure of the first spring 15 is made variable.

The liquid LPG that has flowed into the preheater chamber 40 from the LPG inflow path 9 pushes open the primary valve 11 against the biasing force of the first spring 15 with its own pressure, and causes the wall surface of the primary decompression chamber 6 and the LPG to open. If the temperature difference is sufficiently large, the gas enters the primary decompression chamber 6 and is vaporized under reduced pressure. When the pressure in the primary pressure reducing chamber 6 reaches a predetermined pressure (for example, 0.3 Kg/cm ² ), the first diaphragm 5 releases the first spring 15 provided in the primary pressure regulating chamber 7.
The hook 13 shifts to the left in the figure against the action of
The primary valve 11 is biased toward the closing side by the lever 12, and the primary inflow port 10 is closed. Furthermore, when the pressure in the primary decompression chamber 6 decreases due to fuel consumption, the primary valve 11 is biased toward the opening side, opening the primary inflow port 10 and allowing the LPG inflow path 9 to flow into the preheater chamber 4.
0 into the primary decompression chamber 6.
In this way, the primary valve 11 functions to maintain the pressure within the primary decompression chamber 6 at a predetermined constant value by repeatedly opening and closing the primary inflow port 10. The primary decompression chamber 6 has two slow fuel outlets 4, which will be described later.
A slow fuel passage 43 having numbers 1 and 42 is connected thereto.

The second chamber 4 is divided by a second diaphragm 18 into a secondary pressure reduction chamber 19 and a secondary pressure regulation chamber 20, of which the secondary pressure reduction chamber 19 is divided by a passage 21 penetrating the central partition wall 2 of the casing 1. Primary decompression chamber 6
It is also connected to a mixer (not shown) through a main fuel outlet 22 opening into the secondary decompression chamber 19 and a main fuel passage 23 connected thereto, so that negative pressure is applied to the vent lily. There is. A secondary valve 27 is provided in the secondary decompression chamber 19 to open and close the end of the passage 21 on the secondary decompression chamber side, that is, the secondary inflow port 26 . Atmospheric pressure is introduced into the secondary pressure regulating chamber 20 via a filter 45.

The secondary valve 27 is attached to a lever 29 rotatably supported by a shaft 28, and the secondary valve 27 is attached to a lever 29 rotatably supported by a shaft 28.
It is always biased towards the closing side by the action of the second spring 30 provided within the housing 9. This secondary valve 27 is biased toward the opening side via the pusher 31 by the second diaphragm 18 being biased to the left in the figure by the bench lily negative pressure exerted in the secondary decompression chamber 19. The secondary inflow port 26 is opened and the fuel introduced into the secondary decompression chamber 19 through the passage 21 is decompressed to a pressure of about -2 mmAq while being biased toward the closing side by the action of the second spring 30. It acts to maintain this pressure at a constant level. The fuel in the secondary decompression chamber 19 is taken out from the main fuel outlet 22 due to the pressure difference with the bench lily negative pressure, and is supplied to a mixer (not shown) via the main fuel passage 23. Further, a water jacket 32 through which engine cooling water is circulated is provided in the central partition wall 2 of the regulator, and a water jacket 32 is provided in the central partition wall 2 of the regulator.
The liquid LPG introduced into the engine is heated by engine cooling water.

Next, referring to FIG. 2, there is shown a plan view showing the primary decompression chamber of the regulator of the present invention, and although the regulator in FIG. 2 does not strictly correspond to the structure of the regulator in FIG. This best illustrates the features of the present invention. 21 is the primary decompression chamber 6 and 2
This passage communicates with the secondary decompression chamber 19, and the primary decompression chamber 6 has a first slow fuel outlet 41 opened above the passage 21 and a second slow fuel outlet 42 opened downward from the passage 21. is provided. The first and second slow fuel outlets 41 and 42 are connected to a slow fuel passage 43. In FIG. 2, 46 is an engine cooling water inlet, and 47 is an engine cooling water inlet.
is an engine cooling water outlet, and 48 is a drain.

However, during the first idle after starting the engine when the outside temperature is low, the liquid LPG that has flowed into the preheater chamber 40 from the LPG inflow path 9 is not vaporized in the preheater chamber 40 until the cooling water temperature warms up. The primary valve 11 is pushed open to flow into the primary decompression chamber 6 to a predetermined pressure, e.g.
The pressure is reduced to 0.3Kg/cm ² . However, in this case, liquid
Since the difference between the LPG temperature and the wall temperature of the primary decompression chamber 6 is not very large,
LPG is not vaporized sufficiently and liquid LPG is 1
Next, it begins to accumulate in the decompression chamber 6. When the liquid level rises and reaches the position of the passage 21 that communicates the primary decompression chamber 6 and the secondary decompression chamber 19, the liquid level increases.
LPG comes to flow from the primary decompression chamber 6 to the secondary decompression chamber 19. In such a case, according to the structure of the regulator of the present invention, since the first slow fuel outlet 41 is located above the passage 21, vaporized LPG is taken out from the first slow fuel outlet 41, On the other hand, since the second slow fuel outlet 42 is located below the passage 21, liquid LPG is taken out from the second slow fuel outlet 42.
Gaseous LPG and liquid LPG flowing from the first and second slow fuel outlets 41 and 42 are mixed in the slow fuel passage 43, and the mixed fuel is sent to a bench lily portion of a mixer (not shown).

By appropriately selecting the opening areas of the first and second slow fuel outlets 41 and 42, gaseous
It is possible to obtain the optimal mixture ratio of LPG and liquid LPG, and by supplying this mixed fuel to the mixer, the air-fuel ratio at first idle can be maintained at an optimal level, preventing over-rich or over-lean air-fuel ratio. It is possible to maintain a good first idle at low temperatures.

Effects of the Invention As detailed above, the present invention includes a first slow fuel outlet opening in the primary decompression chamber above a passage communicating between the primary decompression chamber and the secondary decompression chamber, and a Since the second slow fuel outlet is also provided with a second slow fuel outlet that opens downward, a mixture of gaseous and liquid fuel supplied from these slow fuel outlets can always provide a mixture with an optimal air-fuel ratio during first idle. This results in the effect that good first idle operation can be maintained even at low temperatures.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the schematic structure of the regulator for LPG engines of the present invention, Figure 2 is a plan view showing the structure of the primary decompression chamber of the regulator of the present invention, and Figure 3 is the temperature of the propane-n-butane mixed gas. This is a fluff showing a vapor pressure curve. 1...regulator housing, 5...first
Diaphragm, 6...Primary pressure reduction chamber, 7...Primary pressure regulation chamber, 9...LPG inflow path, 11...Primary valve,
15...First spring, 18...Second diaphragm, 19...Secondary pressure reduction chamber, 20...Secondary pressure regulation chamber, 23...Main fuel passage, 27...Secondary valve, 30...Second Spring, 31...Press element,
40... Preheater chamber, 41... First slow fuel outlet, 42... Second slow fuel outlet, 43...
…Slow fuel passage.

Claims (1)

[Scope of utility model registration request] It comprises a primary decompression chamber, a secondary decompression chamber, and a communication passage that communicates these two decompression chambers, and the secondary decompression chamber is connected to a mixer via a fuel passage and is supplied with fuel.
In the regulator for an LPG engine, in which LPG is regulated to a predetermined pressure in the primary decompression chamber and the secondary decompression chamber and supplied to the mixer, a first decompression chamber is provided with a first decompression chamber that opens above the communication passage. A first slow fuel outlet and a second slow fuel outlet opening below the communication passage are provided, and the first and second slow fuel outlet are connected to the mixer via the slow fuel passage. Features: Regulator for LPG engines.