JPH0225028B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fuel heating device for a diesel engine,
In particular, the present invention relates to a device for preheating fuel at low temperatures.

Background technology Light oil is used as a fuel in diesel engines, but light oil has the property of turning into wax at low temperatures.For example, JIS No. 2 light oil is -
It turns into wax at around 10℃. For this reason, there is a problem in that the waxy light oil adheres to the fuel filter at low temperatures, clogging the fuel filter and preventing the light oil from being supplied to the engine body.

Therefore, conventional fuel heating devices have been proposed in which a PTC heating element is installed in the fuel filter, or a nichrome wire is wound around the fuel pipe that supplies fuel to the fuel filter. A bimetal is used as a detector, and when the temperature of the fuel is below a predetermined temperature, the fuel can be heated by the action of the bimetal. Note that the object to be detected by the temperature detector is not limited to the temperature of the fuel filter having the PTC heating element, but may also be the fuel temperature near the filter element of the fuel filter, the cooling water temperature, or the atmospheric temperature. Further, in the conventional device, a manual switch is provided to operate the heating device, and the manual switch is turned on for a predetermined time based on the driver's judgment, thereby turning on the heating device, or A well-known timer is used to keep the heating device on for the time set by the timer.

As described above, according to the conventional device, when the temperature of the fuel is below a predetermined temperature, the fuel is heated, thereby heating the fuel and preventing the fuel from becoming waxy.

However, such conventional devices have the following problems. In other words, while heating the fuel heating device to a predetermined temperature, it heats the fuel flowing inside it, but since heating is usually done only from the outer periphery, it is not possible to sufficiently heat the fuel flowing inside. Ta. In order to solve this problem, if the set heating temperature is increased, the temperature of the outer circumferential portion becomes extremely high, and the fuel that comes into contact with this becomes hotter than a predetermined temperature. Furthermore, if the heating device is made large enough, the entire fuel can be heated, but this poses a problem in that a large space is required to house the heating device.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a fuel heating device for a diesel engine that can effectively heat the fuel flowing inside.

Structure of the Invention In order to achieve the above object, the present invention is a fuel heating device for a diesel engine that heats fuel from a fuel tank storing fuel supplied to the diesel engine, in which a heating element is fixed to the outer periphery. and a cylindrical heating frame having a fuel inlet at the bottom and a fuel outlet at the top; a hollow bottomed cylindrical body having a drain hole at the bottom and a plurality of fuel passage holes around the upper end; a guide frame that is arranged at a predetermined interval inside the cylindrical heating frame to partition and form a thin film-like fuel heating chamber between the guide frame and the inner circumferential surface of the cylindrical heating frame; In order to allow the fuel that has flowed into the heating frame to disperse and pass through the thin-film heating chamber, the bottom wall of the guide frame is disposed toward the fuel inlet of the heating frame, and the upper end of the heating frame is are arranged so as to surround the fuel outlet.

Embodiments Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

Next, FIG. 1 shows a cross section of a fuel heater according to a preferred embodiment of the present invention, and FIG. 2 shows a cross section of FIG. Accordingly, heating efficiency can be improved.

The fuel heater 20 has a fuel tank 12 at one end thereof.
It has an inlet pipe 38 that guides fuel from the
It has an outlet pipe 40 at the other end that supplies heated fuel to the fuel filter 18,
The fuel from the fuel tank 12 is supplied to the fuel heater 20 through the inlet pipe 38 as shown by arrow A, and after being subjected to a predetermined heating action in the fuel heater 20, the fuel is supplied to the fuel heater 20 as shown by arrow B. The fuel is supplied to the fuel filter 18 through the outlet pipe 40 so that the fuel is supplied to the fuel filter 18 through the outlet pipe 40. The fuel heater 20 includes a heating frame 44 having PTC heating elements 42-1 to 42-4 around it and transmitting heat from the PTC heating elements 42-1 to 42-4 to the fuel; A predetermined distance inside the
A heating chamber 48 is formed between the heating frame 44 and the guide frame 46, and a heating chamber 48 is formed between the heating frame 44 and the guide frame 46. Heating of the fuel will take place within 48. The heating frame 44 has a substantially rectangular column shape, and has four flat plates on its four sides.
The PTC heating elements 42-1 to 42-4 are in close contact with each other, and the heating frame 44 is made of a material with good thermal conductivity in order to improve fuel heating efficiency.

The guide frame 46 has a substantially rectangular column shape like the heating frame 44, and the distance between the guide frame 46 and the heating frame 44 is set to about 1 to 5 mm, thereby making the heating chamber 48 narrow. Moreover, since the fuel flowing in from the fuel inlet is guided by the bottom wall of the guide frame 46 and dispersed throughout the heating chamber 48, the heating efficiency of the fuel can be improved.
The guide frame 46 also has a drainage hole 4 at its lower end.
6a, and the water drain hole 46a can prevent water in the fuel from accumulating in the guide frame 46. Further, FIG. 4 shows the appearance of the guide frame 46, and the guide frame 46 has a substantially rectangular column shape as described above, and has fuel passage holes 50-1 to 50 on each of its four sides. -4,
The fuel heated in the heating chamber 48 passes through the passage hole 50-
It will be supplied to the outlet pipe 40 through ports 1 to 50-4.

Therefore, the fuel from the inlet pipe 38 is
As shown by arrows C and D, after being supplied to the heating chamber 48 and subjected to an efficient heating action in the heating chamber 48, the passage holes 50-1 to 50- of the guide frame 46 are supplied.
4 to the outlet pipe 40.

The heating frame 44 and the guide frame 46 are housed within an outer frame 52, and the outer frame 52 is made of a material with good heat resistance and heat insulation. and,
In order to improve the thermal conductivity from the PTC heating elements 42-1 to 42-4 to the heating frame 44, the side surfaces of the PTC heating elements 42-1 to 42-4 are each made of a material with good conductivity. plate 54
-1 to 54-4 are provided, and the plates 54-1
A retainer spring 56 is inserted and fixed between ~54-4 and the outer frame body 52. Therefore, due to the biasing force of the retainer spring 56,
The PTC heating elements 42-1 to 42-4 are connected to the heating frame 4
4, PTC heating elements 42-1 to 42
-4 is evenly adhered to the heating frame 44, so
Heat can be efficiently conducted from the PTC heating elements 42-1 to 42-4 to the heating frame 44, and thereby fuel can be heated efficiently.

In order to support and fix the PTC heating elements 42-1 to 42-4 in the vertical and horizontal directions, the PTC heating elements 42-1 to 42-4 are
Insulator plates 58 made of rubber with good insulation are provided on the upper, lower, left and right end surfaces of the heating elements 42-1 to 42-4. This insulator plate 58 is integrally molded into a substantially rectangular column shape so as to fit around the heating frame 44, and is located at the portions where the PTC heating elements 42-1 to 42-4 contact the heating frame 44. In the insulator plate 58, four holding holes are formed respectively, and the PTC heating elements 42-1 to 42-4 are
It is fitted into the holding hole of the insulator plate 58 and fixed. Therefore, the insulator plate 58 allows the PTC heating elements 42-1 to 42-4 to
2-4 can be reliably supported and fixed in the vertical and horizontal directions.
Heat can be reliably conducted from -1 to 42-4 to the heating frame 44.

A cover 60 is provided above the outer frame 52,
The outlet pipe 40 is fixed to the cover 60 by brazing. And cover 60
has a convex upper part, which allows the air in the fuel heater 20 to be collected at the upper part and escape, which prevents air from accumulating in the fuel heater 20 and having an adverse effect on the pressure sensor 24, etc. This situation can be prevented. Further, in order to attach the fuel heater 20 to the vehicle body, a stay 62 is welded and fixed to the upper part of the cover 60, and a bracket 64 is fixed to the stay 62 by a rivet 66. Note that when the fuel heater 20 is actually attached to a vehicle body, it is preferable to change the shape of the bracket 64 depending on the vehicle body.

In the fuel heater 20, an O-ring 68 is interposed between the heating frame 44 and the cover 60 to seal the fuel side, and also seals the atmosphere side to prevent water and salt water from coming in from the atmosphere side. An upper gasket 70 is provided between the outer frame 52 and the cover 60, and a lower gasket 72 is provided between the heating frame 44 and the outer frame 52. . Therefore, PTC heating elements 42-1~
42-4, oxides and the like are not generated, and deterioration of electrical conductivity and thermal conductivity can be prevented.

In order to supply current to the PTC heating elements 42-1 to 42-4, the plate 54-1 is used as the + electrode of the PTC heating element 42-1, a harness is extended from the plate 54-1, and the heating frame is The terminal 74 below the PTC heating element 42-
1 - electrode, and the current is passed through the PTC heating element 42 - through the plate 54 - 1 and the terminal 74 .
1 will be supplied. Furthermore, terminal 7
4, a washer spring 76 is provided below the terminal 74, and the washer spring 76 presses the terminal 74 against the heating frame 44. Can be done. In addition, in this explanation,
Although the current supply to the PTC heating element 42-1 has been described, the current supply to the PTC heating elements 42-2 to 42-4 is also performed using a similar configuration. Further, as shown in FIG. 3, a ring-shaped insulating plate 78 is formed projecting above the guide frame 46, and this insulating plate 78 thinly enters the upper surface of the heating frame 44 to maintain an insulated state. Therefore, the heating frame 44 and cover 60 are not connected to the vehicle body.

It is understood that the fuel heater according to the embodiment has the above configuration and can efficiently heat the fuel within the heating chamber. That is, fuel from the inlet pipe 38 is supplied to the outlet pipe 40 through the heating chamber 48, and in this heating chamber 48,
The heat from PTC heating elements 42-1 to 42-4 is
The fuel is transmitted from the heating frame 44 made of a material with good thermal conductivity (for example, aluminum), and further, the fuel is transferred to the fuel by the guide frame 46 disposed inside the heating frame 44 with a predetermined distance between them. , flows on the inner surface of the heating frame 44, and therefore the fuel is heated efficiently.

As described above, according to the fuel heater according to the embodiment, fuel can be heated efficiently and heating current can be used effectively.

Furthermore, in the fuel heater of the embodiment, the PTC heating element 42-1 is used as a heating member for heating the fuel.
~42-4 is used, and the PTC heating element is
As the temperature rises, the resistance value increases, which reduces the current flowing through the PTC heating element and acts to keep the temperature from rising above a predetermined temperature, causing the fuel in the heating frame 44 to ignite due to heating. There is no danger.

In addition, in the fuel heater of the example, PTC
Four PTC heating elements 42-1 to 42
- divided into 4 PTC heating elements 42-1 to 44;
-4 in close contact with the periphery of the heating frame 44, the thermal efficiency can be improved, and since the guide frame 46 is placed inside the heating frame 44 with a predetermined distance between them, Improvement in thermal efficiency was obtained. Further, although the guide frame 46 is formed into a substantially rectangular column shape, it is sufficiently effective even if it is cylindrical. Further, in order to improve the efficiency of heat transfer from the heating frame 44 to the fuel, it is preferable to provide fins inside the heating frame 44. Further, in order to improve thermal efficiency, it is preferable that the portions of the guide frame 46 other than the insulating plate 78 be formed of a metal that has good thermal conductivity and is resistant to corrosion.

FIG. 4 shows a configuration example of a system to which a diesel engine fuel heating device according to an embodiment of the present invention is applied.

In FIG. 4, a fuel tank 12 is provided to store fuel to be supplied to the diesel engine 10, and the fuel from the fuel tank 12 is supplied to the diesel engine 10 through a fuel pipe 14. Excess fuel in engine 10 is returned to fuel tank 12 through fuel pipe 16. A fuel filter 18 with a fuel sedimentator is provided between the diesel engine 10 and the fuel tank 12, and the fuel filter 18 separates water in the fuel and removes impurities from the fuel. Can be removed by filtration. Furthermore, a fuel heater 20 is provided between the fuel tank 12 and the fuel filter 18, and the fuel heater 20 heats the fuel from the fuel tank 12, thereby preventing the fuel from becoming waxy. be able to.

A feature of this system is that it is equipped with a temperature sensor that detects the temperature of the fuel and a pressure sensor that detects clogging of the fuel filter by detecting the pressure of the fuel. The state of the fuel is accurately detected based on the pressure signal from the sensor and the fuel is heated. In the embodiment, a temperature sensor 22 is provided between the fuel filter 18 and the fuel heater 20, and a temperature sensor 22 is provided between the diesel engine 10 and the fuel filter 18. A pressure sensor 24 is provided that detects clogging of the fuel filter 18 by utilizing the fact that the pressure of the fuel from the fuel filter 18 is below a predetermined pressure.The temperature sensor 22 and the pressure sensor 24 are connected to a control circuit 26, and Control circuit 2
6 controls the fuel heater 20 based on the temperature signal 100 from the temperature sensor 22 and the pressure signal 102 from the pressure sensor 24.

A power source 28 is provided to supply current to the fuel heater 20 to heat the fuel, and a relay 30 is provided to the power source 28 to control on/off the current supply to the fuel heater 20. It is connected. The relay 30 is controlled by a control circuit 26, a key switch 32 is connected to the control circuit 26, and when the key switch 32 is turned on,
Relay 30 becomes ready for operation. Therefore, after turning on the key switch 32 and starting the engine, the relay 30 becomes ready for operation, and it becomes possible to heat the fuel after starting the engine.

In addition, manual switch 3 is connected in parallel with relay 30.
4 is connected and when the control circuit 26 fails or the driver wishes to heat the fuel,
By operating the manual switch 34, it becomes possible to heat the fuel. Further, an interface 36 is connected to the control circuit 26, and signals such as inputs for detecting engine rotation speed, engine water temperature, and running conditions are supplied to the control circuit 26 via the interface 36.

The system of this embodiment consists of the above configuration,
The following effects will be explained.

At low temperatures For example, when the fuel temperature is at low temperatures below 0° C., the key switch 32 is turned on to start the engine 10, and 1 to 3 minutes after the idle rotation becomes stable or at the start of driving, the temperature sensor 22 detects the temperature of the fuel. Detects the temperature signal 100 and sends it to the control circuit 2
Supply to 6. Note that driving is determined by detecting the gear shift position. Thereafter, the control circuit 26 supplies current to the fuel heater 20 to heat the fuel, and during idling, the fuel is heated for a predetermined time, and when the vehicle is in a running state, the pressure The sensor 24 detects clogging of the fuel filter 18 by detecting the fuel pressure from the fuel filter 18 and provides a pressure signal 102 to the control circuit 26, and the temperature sensor 22 receives the temperature signal 102.
00 to the control circuit 26, and the control circuit 26
controls the fuel heater 20 to properly heat the fuel, prevents the fuel from turning into wax, and prevents the fuel filter 18 from clogging. And for example,
If the engine water temperature is at an appropriate temperature above the warm-up temperature of about 60℃, even if the fuel temperature appears to be atmospheric temperature after restart, if the fuel temperature is above the predetermined temperature, the fuel will not be charged regardless of the timer action. heating is stopped, and the pressure of the fuel from the fuel filter 18 is -150 to -400.
The fuel will not be heated unless the temperature is below about mmHg.

Therefore, when the temperature of the fuel is higher than the predetermined temperature, the fuel will not be heated unless the pressure of the fuel from the fuel filter 18 falls below the predetermined pressure, thereby preventing unnecessary heating of the fuel. Can be done.

As described above, according to the system of this embodiment, the state of the fuel can be accurately detected using the temperature signal from the temperature sensor and the pressure signal from the pressure sensor.
Thereby, the fuel can be appropriately heated. Therefore, compared to the case where the fuel condition is detected using only a temperature sensor, the fuel condition can be detected more accurately and overheating or underheating can be prevented.

In addition, in the pressure detection method of the embodiment, on/off
It is preferable to set the off-state hysteresis to, for example, 50 to 200 mmHg, which allows the fuel to heat up a little longer if the outside air is very cold, which is especially useful in cold weather. be.

Furthermore, in conventional equipment that heats fuel using a manual switch, after the engine starts,
Although there is a drawback that the driver is not aware of the clogging of the fuel filter and the engine stops as a result, in the embodiment, after the engine is started, the temperature of the fuel is detected by a temperature sensor and the fuel is heated. Therefore, it is possible to prevent the fuel from becoming waxy and to prevent the fuel filter from clogging. Therefore, the fuel filter does not become clogged after the engine is started, so the vehicle can be driven safely. In the embodiment, the fuel temperature was detected at the time of engine startup, but it is also possible to detect the temperature of the present device, the temperature of the fuel filter, or the engine water temperature, which can be substituted for the fuel temperature.

Effects of the Invention As explained above, according to the fuel heating device for a diesel engine according to the present invention, since the bottom wall of the guide frame is disposed toward the fuel inlet of the heating frame, the fuel inflows from the inlet. The fuel collides with the bottom wall and is guided, and is effectively dispersed and distributed throughout the thin film-like fuel heating chamber formed around the outer periphery of the cylindrical guide frame. The upper part of this fuel heating chamber is
Since the guide frame is connected to the fuel outlet of the heating frame through the plurality of passage holes provided at the top of the guide frame, the fuel in the fuel heating chamber passes through the plurality of passage holes, making the flow uniform and flowing into the fuel chamber. The flow will not be biased to one side. Therefore, the fuel in the heating chamber flows in a dispersed state throughout the heating chamber, and no short-circuit flow occurs, and heat from the surrounding heating elements can be efficiently transferred to the fuel to heat it. In addition, the fuel that has passed through the multiple passage holes is discharged from the fuel outlet provided inside.
Only one outlet pipe needs to be connected to the heating frame, and although the flow of fuel in the heating chamber is rectified by a plurality of passage holes, the fuel piping does not become complicated. Furthermore, since a drainage hole is formed at the bottom of the guide frame, water that collects inside the guide frame is dispersed into the fuel from here.
Large amounts of water are not introduced into the engine at once.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a fuel heating device for a diesel engine according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. 1, FIG. 3 is an external perspective view of a guide frame, and FIG. FIG. 2 is an explanatory diagram of a system of a fuel heating device for a diesel engine. DESCRIPTION OF SYMBOLS 10... Diesel engine, 12... Fuel tank, 18... Fuel filter with fuel sedimentator, 20... Fuel heater, 22... Temperature sensor, 24... Pressure sensor, 26... Control circuit, 4
2-1 to 42-4...PTC heating element, 44...
Heating frame body, 46... Guide frame body, 48... Heating chamber, 50-1 to 50-4... Passing hole.

Claims (1)

[Scope of Claims] 1. A fuel heating device for a diesel engine that heats fuel from a fuel tank that stores fuel supplied to the diesel engine, comprising: a heating element fixed to the outer periphery, a fuel inlet at the bottom; A cylindrical heating frame with a fuel outlet formed at the top, a hollow bottomed cylindrical body with a water drain hole at the bottom and a plurality of fuel passage holes around the upper end, and an inner side of the cylindrical heating frame. a guide frame that partitions and forms a thin film-like fuel heating chamber between the guide frame and the inner circumferential surface of the cylindrical heating frame;
The bottom wall of the guide frame is disposed toward the fuel inlet of the heating frame, and the bottom wall of the guide frame is disposed toward the fuel inlet of the heating frame, so that the fuel flowing into the heating frame is dispersed and passed through the thin film heating chamber. A fuel heating device for a diesel engine, characterized in that an upper end of the fuel heating device is disposed so as to surround the fuel outlet. 2. In the device according to claim 1, the fuel heater has a heating frame having a PTC heating element around it, and a fuel passage hole arranged at a predetermined distance inside the heating frame. What is claimed is: 1. A fuel heating device for a diesel engine, comprising: a guide frame; the fuel is heated in a heating chamber formed between the heating frame and the guide frame;