JPH0517414Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel cooling system, and more particularly to an apparatus for cooling alcohol fuel or gasoline fuel that has reached a high temperature in an engine room by using the fuel itself as a refrigerant.

[Prior Art] Generally, alcohol fuel and gasoline fuel have a low boiling point, and in an engine room where the temperature is high at 50 to 90° C. or higher, these fuels tend to generate vapor within the injection system. In particular, the nozzle return that receives heat from the engine and the overflow that is pressurized by the pump become even hotter. For example, methanol has evaporation temperature characteristics as shown in Figure 9 and generates vapor even at relatively low temperatures.In a methanol diesel engine that uses this methanol as fuel for in-cylinder injection, when methanol fuel generates vapor, it is injected. It becomes impossible for the pump to pump fuel, and as a result, the engine becomes inoperable.

[Problems to be Solved by the Invention] Therefore, if an attempt is made to cool the fuel by circulating refrigerant using a compressor, auxiliary equipment loss will be caused by the work of the compressor.

In addition, in an alcohol reformed gas engine, gas fuel reformed from alcohol fuel is introduced into the inner pipe of the double pipe, and alcohol fuel is introduced between the inner pipe and the outer pipe, so that these gas fuels and alcohol fuel can be combined. A gas cooler that cools gas fuel by exchanging heat with the gas is proposed in Japanese Utility Model Application Publication No. 112070/1983. However, in this gas cooler, alcohol fuel is reformed into gas fuel in a reformer and then this gas fuel is cooled, so it is necessary to have both a reformer and a gas cooler, which increases the size of the device and reduces thermal efficiency. Also, since it has a double pipe structure, there is a problem that its maintenance is not easy.

Thus, the purpose of the present invention is to solve the above-mentioned conventional problems, to prevent the generation of fuel vapor in the injection system, to ensure stable operation of the engine, and to provide a fuel cooling system that is small and has good thermal efficiency. .

[Means for Solving the Problems] In order to achieve the above object, the fuel cooling system of the present invention cools the primary fuel supplied from the fuel tank to the injection pump by using the latent heat of vaporization of the secondary fuel. A cooling heat exchanger is provided, and the secondary fuel vaporized by the heat exchanger is guided to the intake manifold.

[Operation] By providing such a heat exchanger, the primary fuel is cooled and then supplied to the injection pump, and the vaporized secondary fuel is supplied to the engine via the intake manifold. Therefore, without providing both a reformer and a gas cooler as in the prior art, generation of fuel vapor within the injection system is prevented and ignition stability is improved.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a fuel cooling system according to a first embodiment of the present invention. The fuel tank 1 is connected to an injection pump 3 via a filter 2 by a fuel pipe, and the fuel pipe connecting the filter 2 and the injection pump 3 passes through the inside of the evaporator 4. Further, the nozzle 5 connected to the injection pump 3 is connected to the electromagnetic pump 8 via the receiver 7 together with the overflow pipe 6 of the injection pump 3, and the electromagnetic pump 8 is further connected to the evaporator 4 via the expansion valve 9. is connected to the body of the The other end of the body of the evaporator 4 is connected to an intake duct 10. Further, the fuel tank 1 and the receiver 7 are connected via an electromagnetic pump 11.

Next, the operation of this embodiment will be explained.

First, fuel _F1 is supplied from the fuel tank 1 to the injection pump 3 via the filter 2, but it is heated in the engine room and reaches a high temperature. Therefore, when the electromagnetic pump 8 is driven, fuel F ₂ due to overflow from the injection pump 3 and nozzle return from the nozzle 5 is guided into the body of the evaporator 4 via the receiver 7 and the expansion valve 9. This fuel F ₂ is vaporized in the evaporator 4 due to its own temperature and negative pressure in the intake duct 10 , and is supplied to the engine 13 via the intake manifold 12 . Fuel vaporized in this way
The fuel F ₁ flowing through the evaporator 4 is cooled by the latent heat of vaporization of F ₂ and is supplied to the injection pump 3 .

Note that by adjusting the excess or deficiency of fuel F ₂ serving as a refrigerant using the electromagnetic pump 11, a constant flow rate of refrigerant can be supplied into the body of the evaporator 4.

Moreover, as the evaporator 4, those having various structures can be used. For example, as shown in FIG.
Further, as shown in FIG. 3, a structure in which a heat dissipation plate 31 is also provided on the inner peripheral portion of the through pipe 23 may be used. In addition, as shown in FIGS. 4a and 4b, a structure in which a through pipe 41 is made to meander within the body 42 and a heat sink 43 is provided, and as shown in _FIG .
are branched, and a fifth
A structure may also be used in which heat dissipation fins 53 as shown in _FIG .

FIG. 6 shows the configuration of a fuel cooling system according to a second embodiment. This embodiment is based on the first
In this embodiment, a temperature sensor 61 for detecting the temperature T _{F of the fuel F 1 is provided immediately downstream of the evaporator 4 in the fuel pipe connected from the filter 2 to the injection pump 3 , and a temperature sensor 61 is provided to detect the temperature T F} of the fuel F ₁ . Suction blower 62 between
Further, the fuel temperature from the temperature sensor 61 is
A control section 63 is provided to control the driving of the suction blower 62 and the electromagnetic pump 8 based on T _F. As the electromagnetic pump 8, a variable displacement electromagnetic pump is used.

The operation of the control section 63 will be explained with reference to the flowchart of FIG. First, the fuel temperature T _F detected by the temperature sensor 61 is input (process 71), and it is determined whether this temperature T _F has become equal to or higher than a preset temperature T _FS (process 72). As a result of the determination, if T _F <T _FS , both the suction blower 62 and the electromagnetic pump 8 are turned off, and the evaporator 4 is turned off.
The supply of fuel _F2 , ie, refrigerant, into the body is stopped (process 73). On the other hand, when T _F ≧ T _FS , it is determined that the fuel F ₁ has become high temperature, and the suction blower 62 is driven (process 74), and as shown in _FIG. Electromagnetic pump 8
(processing 75), and driving the electromagnetic pump 8 with this duty ratio (processing 7).
6). In this way, refrigerant at a flow rate corresponding to the fuel temperature T _F is supplied into the body of the evaporator 4,
Fuel F ₁ is cooled.

With this configuration, the fuel, such as methanol, is cooled only when the temperature of the fuel increases to near the evaporation start temperature, resulting in energy savings.

Note that instead of the electromagnetic pump 8 of the variable capacity section, an electromagnetic valve controlled by the control section 63 and a fixed capacity electromagnetic pump may be used. Furthermore, a throttle valve may be provided on the intake duct side to generate negative pressure.

[Effects of the invention] As explained above, according to the present invention, the following excellent effects are achieved.

(1) The fuel in the injection system can be cooled, and as a result, vapor generation is prevented. Therefore, it is possible to prevent the sliding portion from being worn out due to a decrease in the viscosity of the fuel.

(2) Ignition stability is improved because vaporized fuel used as a refrigerant is supplied to the engine via the intake manifold.

(3) Since the heat exchanger cools the primary fuel and vaporizes the secondary fuel at the same time, it is possible to realize a compact cooling system with good thermal efficiency.

(4) No compressor is used for cooling, so there is no loss in auxiliary equipment.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a fuel cooling system according to a first embodiment of the present invention, FIGS. 2 to 5 are respective examples of the configuration of an evaporator, FIG. 6 is a configuration diagram of a second embodiment, and FIG. 8 and 8 are explanatory diagrams showing the operation of the second embodiment, and FIG. 9 is a diagram showing the evaporation temperature characteristics of methanol. In the figure, 1 is a fuel tank, 3 is an injection pump, 4 is an evaporator, 8 is an electromagnetic pump, 1
0 is an intake duct, 12 is an intake manifold, and 13 is an engine.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A heat exchanger is provided to cool the primary fuel supplied from the fuel tank to the injection pump using the latent heat of vaporization of the secondary fuel, and the heat exchanger is used to vaporize the primary fuel supplied from the fuel tank to the injection pump. A fuel cooling system characterized by being configured to guide secondary side fuel to an intake manifold. (2) The fuel cooling system according to claim 1, wherein the secondary fuel contains the overflow or nozzle return of the injection pump. (3) The scope of the utility model registration according to claim 1 or 2, wherein the supply of secondary fuel to the heat exchanger is controlled based on the temperature of the primary fuel discharged from the heat exchanger. Fuel cooling system. (4) The fuel cooling system according to any one of claims 1 to 3, wherein the primary fuel and the secondary fuel are methanol.