JP2003120443A - Fuel supplying system for liquefied gas fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a simple structure and cost reduction as a fuel supply system using liquefied gas fuel. SOLUTION: The liquefied gas fuel in a fuel tank 10 is compressed to a common rail 15 through a low-pressure pump 11 and a high-pressure pump 13, and is then injected into an engine from a fuel injection valve 20. The liquefied gas fuel leaking from the high-pressure pump 13, the common rail 15, and the fuel injection valve 20 is collected into a fuel retrieve tank 17. An air conditioner using the liquefied gas fuel as a refrigerant is provided and the liquefied gas fuel in the fuel tank 10 is discharged from the low-pressure pump 11, and is then returned to the fuel tank 10 through an expansion valve 32, an evaporator 35, the fuel collection tank 17, a compressor 40, a condenser 42 or the like. In this case, the leaking fuel collected in the fuel collection tank 17 is liquefied in the compressor 40 and the condenser 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for liquefied gas fuel, which system includes a fuel injection device and an air conditioner.

[0002]

2. Description of the Related Art In diesel engines, light oil is generally used as a fuel, but DME (dimethyl ether) and an additive for improving the cetane number are taken into consideration in consideration of fuel vaporization property, ignition and combustion property, emission and the like. With LPG
The use of a liquefied gas fuel such as (liquefied petroleum gas) has been studied (in the following description, what is referred to as LPG refers to one to which a cetane number improver is added unless otherwise specified). As a fuel injection device for liquefied gas fuel, a common rail fuel injection device for diesel engines can be applied. That is, a high-pressure pump is connected to the fuel tank for storing the liquefied gas fuel through the fuel supply pipe, and the high-pressure fuel is discharged from the high-pressure pump to the common rail as the high-pressure pump is driven. Then, the high-pressure fuel is accumulated on the common rail at a pressure corresponding to a predetermined injection pressure, and then injected from the fuel injection valve.

Further, a fuel injection valve utilizing a hydraulic servo mechanism is used, and in the case of this fuel injection valve, it is necessary to leak fuel for hydraulic control. A fuel injection valve that uses a hydraulic servo mechanism is known as a fuel injection valve that uses a two-way valve or a three-way valve, and high-pressure fuel is introduced into a pressure control chamber that is provided on the back surface of the valve body. The valve opening operation of the valve body is realized by leaking the high pressure fuel (hydraulic pressure) to the low pressure side every injection. In this case, DME
Liquefied gas fuel such as LPG and LPG is a gas at normal temperature and pressure, and the fuel leaked from the fuel injection valve is vaporized.
A processing device for collecting and liquefying is required.

A device for recovering leaked fuel is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Laid-Open No. 1-22590, and its outline will be described with reference to FIG. In FIG. 2, the fuel in the fuel tank 50 is discharged from the low pressure pump 51, and the high pressure pump 52
After being compressed to a high pressure at, it is fed to the common rail 53. Fuel injection valves 54 are connected to the common rail 53 for the number of engine cylinders. The fuel leaked from the high-pressure pump 52, the fuel injection valve 54, etc. is once collected in a fuel recovery tank (purge tank) 55, then liquefied by the fuel compression compressor 56 and returned to the fuel tank 50.

In the configuration shown in FIG. 2, a recovery device such as a fuel recovery tank 55 and a fuel compression compressor 56 for recovering leaked fuel is required, which causes problems that the structure is complicated and the cost is increased.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to simplify the structure as a fuel supply system using liquefied gas fuel and to reduce the cost. To reduce it.

[0007]

In the fuel supply system for liquefied gas fuel according to the first aspect, the liquefied gas fuel in the fuel tank is supplied to the fuel injection device through the fuel pipe. Further, in this system, an air conditioner including at least an expansion valve, an evaporator and a condenser is provided, and the liquefied gas fuel in the fuel tank is supplied as a refrigerant to the air conditioner. Further, the liquefied gas fuel leaked from the fuel injection device is introduced into the air conditioner. The liquefied gas fuel introduced into the air conditioner is mixed with the liquefied gas fuel circulating in the air conditioner as a refrigerant and flows downstream.

According to the above construction, the liquefied gas fuel leaked from the high-pressure pump, the fuel injection valve, etc. constituting the fuel injection device is liquefied by the air conditioner (condenser) and returned to the fuel tank through this air conditioner. Therefore, no additional structure is required as the fuel recovery device. In addition, in addition to the original role of liquefying the refrigerant (liquefied gas fuel), the condenser of the air conditioner plays a role of collecting leaked fuel, so that the condenser can be shared. As a result, the structure of the fuel supply system can be simplified and the cost can be reduced.

According to the first aspect of the present invention, as described in the second aspect, it is preferable that the liquefied gas fuel leaked from the fuel injection device is discharged between the evaporator and the condenser of the air conditioner.

Further, in the third aspect of the invention, a fuel recovery tank for recovering the liquefied gas fuel leaked from the fuel injection device is installed between the evaporator and the condenser of the air conditioner. In this case, the leaked fuel from the fuel injection device is once recovered in the fuel recovery tank and then liquefied by the air conditioner.

Further, in the invention according to claim 4, the liquefied gas fuel in a liquid state is stored in the fuel tank, and the liquefied gas fuel in the liquid state is fed to the expansion valve of the air conditioner. After that, it was configured to be returned to the fuel tank via the evaporator and the condenser. In this case, the liquefied gas fuel in the liquid state can be supplied to the expansion valve immediately after the engine is started, and the cooling effect and the like by the air conditioner can be quickly obtained.

[0012] In the invention according to claim 5, an air conditioner control valve that opens and closes according to whether the air conditioner is operating or not is provided in the fuel passage for feeding the liquefied gas fuel in the fuel tank to the expansion valve. installed. By opening or closing the air conditioner control valve, activation / deactivation of the air conditioner can be adjusted as desired. Even when the air conditioner control valve is closed to deactivate the air conditioner (air conditioner OFF), the leak fuel can be liquefied separately by the condenser.

According to the sixth aspect of the invention, the fuel passage for returning the liquefied gas fuel after passing through the condenser to the fuel tank allows only the flow of the liquefied gas fuel from the condenser side to the fuel tank. A stop valve was installed. In this case, backflow of the liquefied gas fuel from the fuel tank to the condenser side can be prevented.

According to the invention described in claim 7, the pressure in the fuel tank is made substantially equal to the saturated vapor pressure of the liquefied gas fuel, and the low pressure pump is arranged in the fuel tank. That is, when the pressure in the fuel tank is substantially equal to the saturated vapor pressure of the liquefied gas fuel, the temperature of the liquefied gas fuel locally rises slightly or the pressure in the fuel tank slightly drops, and bubbles (vapor) are generated. Occur. In this case, by incorporating the low-pressure pump in the fuel tank, it is possible to prevent bubbles from being generated due to a pressure drop in the path from the fuel tank to the low-pressure pump, and to prevent suction failure of the low-pressure pump. At the same time, the temperature difference between the fuel tank and the low-pressure pump decreases,
It is possible to prevent bubbles from being generated due to a temperature difference and a suction failure of the low-pressure pump due to the bubbles.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In this embodiment,
In a fuel supply system including a fuel injection device for injecting a liquefied gas fuel such as DME or LPG into a diesel engine, the liquefied gas fuel is used as a refrigerant for an air conditioner, and a common rail type fuel injection device is used. Adopt a fuel injection device. FIG. 1 is a configuration diagram showing a common rail fuel injection device and an air conditioner provided accompanying it.

In FIG. 1, the fuel tank 10 has a DM
Liquefied gas fuel such as E or LPG is stored in a liquid state. The pressure in the fuel tank 10 is equal to the saturated vapor pressure of the liquefied gas fuel, and the liquefied gas fuel is used as DME.
When using, the saturated vapor pressure of DME is about 0.6 MPa at room temperature (25 ° C.). A low-pressure pump 11 is arranged in the fuel tank 10, and the liquefied gas fuel pressurized by the low-pressure pump 11 to a predetermined feed pressure (about 3 MPa) is delivered to the high-pressure pump 13 via a pipe 12. .

Here, the pressure in the fuel tank 10 is equal to the saturated vapor pressure of the liquefied gas fuel, and the temperature of the liquefied gas fuel locally rises slightly or the pressure in the fuel tank 10 slightly decreases to cause bubbles. (Vapor) is generated. In such a case, by incorporating the low-pressure pump 11 in the fuel tank 10, generation of bubbles due to pressure drop in the path from the fuel tank 10 to the low-pressure pump 11 and the resulting suction failure of the low-pressure pump 11 are prevented. At the same time, the temperature difference between the fuel tank 10 and the low-pressure pump 11 is reduced, and the generation of bubbles due to the temperature difference and the suction failure of the low-pressure pump 11 due to this are prevented.

The high-pressure pump 13 compresses the liquefied gas fuel to a high pressure (about 35 MPa) equivalent to the injection pressure, and pumps the high-pressure fuel to the common rail 15 via the pipe 14. The liquefied gas fuel leaked from the sliding portion and the seal portion of the high-pressure pump 13 is recovered in the fuel recovery tank 17 through the pipe 16. The common rail 15 and the fuel recovery tank 17 are connected by a pipe 18, and a pressure limiting valve 19 is provided in the middle of the pipe 18. In this case, common rail 1
Excess fuel is recovered in the fuel recovery tank 17 via the pressure limiting valve 19 so that the fuel pressure in 5 does not exceed a predetermined pressure (about 35 MPa).

Fuel injection valves 20 for the number of engine cylinders are connected to the common rail 15, and the high-pressure fuel stored in the common rail 15 is injected and supplied to the diesel engine as the fuel injection valves 20 are driven. Fuel injection valve 20
Is composed of an electromagnetic control valve 20a that intermittently supplies high-pressure fuel from the common rail 15, and an injection nozzle 20b that moves a valve body in accordance with the driving of the electromagnetic control valve 20a and injects fuel from the nozzle tip. The fuel injection valve 2
The drive of 0 is controlled by a microcomputer (not shown). The liquefied gas fuel leaked from the sliding portion of the valve body of the fuel injection valve 20 passes through the pipe 21 and the fuel recovery tank 17
Will be collected.

Next, the air conditioner will be described. The liquefied fuel pressurized to about 3 MPa by the low-pressure pump 11 is sent to the expansion valve (expansion valve) 32 through the pipe 31. An air conditioner control valve 33 is installed in the middle of the pipe 31.
The air conditioner is controlled by 3 to be in an operating or non-operating state. For example, when an air conditioner switch (not shown) is turned on by a vehicle passenger, the air conditioner control valve 33 is opened,
The passage of the liquefied gas fuel from the fuel tank 10 toward the expansion valve 32 is permitted. When the air conditioner switch is turned off, the air conditioner control valve 33 is closed and the fuel tank 1
The passage of the liquefied gas fuel from 0 toward the expansion valve 32 is blocked.

In the expansion valve 32, the liquefied gas fuel in the liquefied state is rapidly expanded into a low-temperature, low-pressure mist state, and the mist-like fuel passes through the pipe 34 and the evaporator (evaporator) 3
Flow to 5. In the evaporator 35, the latent heat required for evaporation is taken from the surrounding air through the evaporator fins,
Ambient air is cooled. At this time, the blower motor 36 is driven to cool the vehicle interior air. Evaporator 35
The liquefied gas fuel vaporized in (1) is sent to the fuel recovery tank 17 through the pipe 37.

A heat-sensitive cylinder 38 is installed in the pipe 37, and the expansion valve 3 is responsive to the fuel temperature sensed by the heat-sensitive cylinder 38.
The opening degree of 2 is adjusted. That is, when the fuel temperature is high, the opening degree of the expansion valve 32 is large, and when the fuel temperature is low, the opening degree of the expansion valve 32 is small.

The liquefied gas fuel recovered in a gaseous state in the fuel recovery tank 17 passes through the pipe 39 and the compressor 4
0, and is sucked and compressed by the compressor 40.
The liquefied gas fuel whose temperature and pressure have been increased by the compressor 40 flows into the condenser (condenser) 42 through the pipe 41. Then, in the condenser 42, the liquefied gas fuel is cooled by the engine cooling fan 43 and the like, and the latent heat of condensation is removed to be liquefied. The liquefied liquefied gas fuel flows into the receiver tank 44, where it is separated into gas and liquid, and only the liquid passes through the pipe 45 and the fuel tank 10.
Sent to.

A check valve 46 is provided in the middle of the pipe 45. According to the check valve 46, the receiver tank 44 is provided.
Only the fuel flow from the (condenser 42 side) to the fuel tank 10 is allowed. Therefore, the liquefied gas fuel in the fuel tank 10 is prevented from flowing back to the receiver tank 44 when the engine is stopped.

In the configuration of FIG. 1 described above, in the common rail type fuel injection device, the high pressure pump 13, the common rail 15,
The liquefied gas fuel leaked from the fuel injection valve 20 or the like is temporarily collected in the fuel recovery tank 17 and then the compressor 40
And is liquefied by the condenser 42. After that, it is returned to the fuel tank 10. In this case, the compressor 40
In addition to the original role of liquefying the refrigerant (liquefied gas fuel), the condenser 42 plays a role of leak fuel recovery,
The compressor 40 and the condenser 42 can be commonly used.

In the present embodiment, because the compressor 40 is shared by the fuel injection device and the air conditioner, the operation of the compressor 40 is always ON during engine operation, but the air conditioner control valve 33 operates the air conditioner. ON / optional
It is turned off. At this time, even when the air conditioner control valve 33 is closed to deactivate the air conditioner (air conditioner OFF), the leak fuel is liquefied separately by the compressor 40 and the condenser 42.

According to this embodiment described in detail above, the following effects can be obtained. Since the compressor 40 and the condenser 42 are shared by the common rail fuel injection device and the air conditioner, unlike the prior art, there is no need for a fuel compression compressor dedicated to fuel recovery. as a result,
The structure of the fuel supply system can be simplified and the cost can be reduced. Of course, a vehicle equipped with the system can also realize cost reduction.

Since the liquefied gas fuel in a liquid state is stored in the fuel tank 10 and the liquefied gas fuel in the liquid state is fed to the expansion valve 32 of the air conditioner, the liquefied gas fuel is kept in a liquid state immediately after the engine is started. Liquefied gas fuel can be supplied to the expansion valve 32. That is, the refrigerant (liquefied gas fuel) is vaporized when the engine is normally stopped, but it is not necessary to wait for the refrigerant to be liquefied immediately after the engine is started. As a result, the cooling effect in the vehicle interior can be quickly obtained.

Since the low pressure pump 11 is built in the fuel tank 10, the pressure drop in the path from the fuel tank 10 to the low pressure pump 11 and the fuel tank 10 and the low pressure pump 1
It is possible to prevent bubbles from being generated due to a temperature difference from the temperature difference between the low pressure pump 1 and the low pressure pump 11.

The present invention can be embodied in the following modes other than the above. The position where the leaked fuel from the fuel injection device is discharged to the air conditioner side is not limited to between the evaporator (evaporator) 35 and the compressor 40. The point is that it is possible to liquefy the leaked fuel, and it can be arbitrarily changed as long as the leaked fuel is discharged to the upstream side of the condenser (condenser) 42.

In the above embodiment, the compressor 40 is used as an air conditioner, but it is also possible to realize the air conditioner without using the compressor 40.
In particular, when liquefied gas fuel (DME, LPG, etc.) is used as the refrigerant, the liquefied gas fuel (refrigerant) can be liquefied only by cooling / condensing with the condenser 42, and is realized as an air conditioner.

Alternatively, it is possible to embody this system without using the fuel recovery tank 17. In this case, the leaked fuel from the fuel injection device may be directly discharged to the pipe (for example, the pipe 39 in FIG. 1) in the air conditioner.

In the above embodiment, the common rail type fuel injection device is used as the fuel injection device, but other types of fuel injection device may be used. For example, instead of using a common rail, a distribution type fuel injection pump may be used to increase the pressure of the liquefied gas fuel and supply it to the fuel injection valve.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a common rail fuel injection device and an air conditioner provided accompanying it.

FIG. 2 is a configuration diagram showing a fuel recovery device according to a conventional technique.

[Explanation of symbols]

10 ... Fuel tank, 11 ... Low-pressure pump, 12 ... Piping, 1
7 ... Fuel recovery tank, 31 ... Piping, 32 ... Expansion valve, 33
… Air conditioner control valve, 35… Evaporator, 4
0 ... Compressor, 42 ... Condenser (condenser), 45
… Piping, 46… Check valve.

Continued front page    (72) Inventor Moriyasu Goto             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Tetsuo Morita             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Masaaki Kato             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3K068 AA02 AB12 AB14 AB28 AB29                       BA01 BB01 BB02 BB11 CB02

Claims (7)

[Claims] 1. An expansion valve for atomizing a liquid refrigerant and an expansion valve in a fuel supply system for supplying liquefied gas fuel in a fuel tank to a fuel injection device for injecting fuel into an engine through a fuel pipe. And an evaporator that vaporizes the atomized refrigerant, and an air conditioner that includes at least a condenser that condenses and liquefies the vaporized refrigerant, and supplies the liquefied gas fuel in the fuel tank as a refrigerant to the air conditioner. A fuel supply system for liquefied gas fuel, characterized in that liquefied gas fuel leaked from a fuel injection device is introduced into the air conditioner. 2. The fuel supply system for liquefied gas fuel according to claim 1, wherein the liquefied gas fuel leaked from the fuel injection device is discharged between the evaporator and the condenser of the air conditioner. 3. Between the evaporator and the condenser of the air conditioner,
The fuel supply system for liquefied gas fuel according to claim 2, further comprising a fuel recovery tank for recovering the liquefied gas fuel leaked from the fuel injection device. 4. A liquefied gas fuel in a liquid state is stored in a fuel tank, and the liquefied gas fuel in the liquid state is fed to an expansion valve of the air conditioner, and then passed through an evaporator and a condenser. 4. The fuel tank is configured to be returned to the fuel tank.
A fuel supply system for a liquefied gas fuel according to any one of 1. 5. An air conditioner control valve that opens and closes according to whether the air conditioner is operating or not is installed in a fuel passage for feeding liquefied gas fuel in a fuel tank to the expansion valve.
5. A fuel supply system for liquefied gas fuel according to any one of 1 to 4. 6. A check valve for allowing only the flow of the liquefied gas fuel from the condenser side to the fuel tank is installed in the fuel passage for returning the liquefied gas fuel after passing through the condenser to the fuel tank. The fuel supply system for liquefied gas fuel according to any one of 1 to 5. 7. The fuel for liquefied gas fuel according to claim 1, wherein the pressure in the fuel tank is made substantially equal to the saturated vapor pressure of the liquefied gas fuel, and a low pressure pump is arranged in the fuel tank. Supply system.