JPS6363744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel heating device used in a fuel supply system of an engine or the like.

[Prior Art] For example, in the fuel supply system of a diesel engine vehicle, wax deposited from the fuel at low temperatures tends to clog the filter element of the fuel filter, causing a problem in which the fuel stops flowing. As a countermeasure for this problem, different types of light oil are supplied depending on the usage environment, but when the temperature exceeds the usage limit, clogging of the filter element is still unavoidable. Therefore, a device has been developed in which the fuel filter portion is provided with a heater for heating the fuel.

By the way, this type of fuel heating device includes one that uses a temperature sensing method and one that uses a differential pressure sensing method. That is, in the temperature sensing method, the temperature of the fuel passing through the filter element is sensed by a bimetal or the like to control the heater on and off. This device has the advantage of having a simple structure with a small number of parts, but on the other hand, if the fuel temperature falls below a set value, the heater is energized uniformly. ,
Since low-temperature fuel is used, power may be unnecessarily supplied to the heater even in a temperature range where there is no fear of filter element clogging, resulting in a problem that the battery charging and discharging balance deteriorates.

On the other hand, the differential pressure sensing method detects the pressure difference between the fuel before and after the filter element, and energizes the heater when the differential pressure exceeds a set value. However, in this case, the heater operates only when the flow path resistance of the filter element increases, so if there is no wax precipitation even though the temperature is quite low due to the use of low-temperature fuel, No current is applied to the energized heater. Therefore, the drawbacks of the temperature sensing method described above can be overcome. However, this differential pressure sensing type has a problem in that it is activated not only when wax deposits at low temperatures but also when the filter element is clogged with foreign matter.

By the way, there is also a prior art of this type of fuel heating device as disclosed in Japanese Utility Model Application Publication No. 59-131963. In other words, this sensor includes a cooling water temperature sensor that detects engine cooling water temperature, a temperature sensor that detects fuel temperature, a pressure sensor that detects the pressure of fuel supplied to the fuel filter, and an atmospheric temperature sensor that detects atmospheric temperature. Input the signals to the control device, and compare each detection signal with each predetermined setting value within this control device,
Electric power is supplied to the heater when the detection output of any of the sensors mentioned above exceeds the corresponding set value. In this case, the heater can be energized under many conditions under which it can be determined that wax has deposited, so that clogging of the filter element due to wax deposition can be effectively prevented. However, this prior art has the disadvantages of the temperature sensing method mentioned above,
This paper is not intended to eliminate the drawbacks of the differential pressure sensing method, nor is it intended to disclose or suggest any technique for doing so.

[Problems to be solved by the invention] The present invention solves the problems of the temperature sensing method,
In other words, since low-temperature fuel is used, the heater is energized even in a temperature range where there is no risk of wax deposition, and the differential pressure sensing method has the following problems: The purpose of this invention is to simultaneously solve the problem of erroneously supplying power to the heater even when the filter element is clogged due to dust or the like rather than wax deposition, with a simple configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a fuel heating device including a heater for heating fuel to be passed through a filter element of a fuel filter, and a first and a second heater. a switch mechanism that controls energization to the heater by connecting and separating contacts; a temperature-sensitive actuator that moves the first contact toward the second contact when the fuel temperature is low; and a difference in fuel before and after the filter element. A differential pressure actuator that moves the second contact toward the first contact as the pressure increases, and only when the fuel temperature is low and the differential pressure of the fuel before and after the filter element is large. The present invention is characterized in that the heater is configured to be energized.

[Function] With this configuration, power is supplied to the heater and the fuel is heated only when the fuel temperature shows a low value and the differential pressure of the fuel before and after the filter element increases abnormally. will be
Under other circumstances, the heater is not energized.

That is, if the fuel temperature is low and the first contact moves toward the second contact, but the differential pressure across the filter element does not exceed a certain value, the first
Since the contacts are retracted, the first and second contacts will not come into contact and energize the heater.

Furthermore, even if the differential pressure across the filter element exceeds a certain value and the second contact moves toward the first contact, if the fuel temperature has risen to a value at which wax precipitation cannot occur, Since the first contact is retracted, the first and second contacts do not come into contact and energize the heater.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a fuel filter 4 is interposed in the middle of a fuel path 3 that connects a fuel tank 1 for a diesel engine and a fuel injection pump 2. As shown in FIG.

As schematically shown in FIG. 1, the fuel filter 4 has a filter cartridge 6 removably attached to the lower surface 5a of the head cover 5. The head cover 5 is block-shaped and has a fuel introduction path 7 and a fuel outlet path 8 inside thereof. The fuel introduction path 7 includes a starting end passage 9 having a check valve (not shown), a pump chamber 11 connected to the starting end passage 9 and provided at the upper end of the head cover 5, and a port 12 in the pump chamber 11. It is composed of a heater chamber 13 that communicates with the heater chamber 13 through the heater chamber 13, and a terminal end passage 14 that communicates with the heater chamber 13 through a check valve (not shown). An opening is provided on the lower surface of the protruding mounting shaft portion 15. And the heater chamber 13
A heater 16 for heating the fuel F passing through this fuel introduction path 7 is disposed. on the other hand,
The fuel outlet path 8 is connected to the lower surface 5 of the head cover 5.
An annular groove 17 is formed in a to surround the mounting shaft portion 15, and this annular groove 17 is connected to the outlet port 1.
It is opened to the outside through 8.

A switch mechanism 19 for controlling the supply of electricity to the heater 16 is provided within the head cover 5, as shown in principle in FIG. Specifically, the upper end electrode 16a of the heater 16 is connected to the partition wall 2 between the pump chamber 11 and the heater chamber 13, which also serves as an electrode plate.
1 to the (-) side terminal of a battery (not shown). Further, the lower end electrode 16b of the heater 16 is connected to an electrode plate 23 held by an insulating material 22, and this electrode plate 23 is connected to the switch mechanism 19.
It is connected to the (+) side terminal of the battery via. The switch mechanism 19 includes a first contact 25 which is constantly connected to the electrode plate 23 via a conductive spring 24.
and a second contact 26 arranged opposite to the first contact 25. And the first contact point 2
5 to the second contact 2 by the temperature-sensitive actuator 27.
The second contact 26 can be moved toward and away from the first contact 25 by a differential pressure actuator 28. That is, the temperature-sensitive actuator 27
is formed by fixing the first contact point 25 to the center of a dish-shaped bimetal 29. When the temperature of the fuel F is low, the first contact point 25 is moved downward in the figure, and the fuel F The structure is such that it can be moved upward in the figure when the temperature of the temperature increases. On the other hand, the differential pressure actuator 28 has its axis centered at the first contact point 25.
A piston 32 is slidably housed in a cylinder 31 formed to match the axis of the piston 32, and a second contact 26 is fixed to the tip of a piston rod 33 that projects from the upper end of the piston 32. The lower end of the cylinder 31 is communicated with the fuel introduction path 7 via a sensing port 34, and the upper end is communicated with the fuel outlet path 8 via a sensing port 35. Furthermore, a coil spring 36 for setting operating characteristics is interposed between the upper end of the cylinder 31 and the upper end of the piston and is wound around the piston rod 33. The spring constant of the coil spring 36 is such that, for example, when the differential pressure across the filter element (described later) is 200 mmHg, the piston 32 reaches the top dead center, and when the differential pressure is 100 mmHg, the piston 32 reaches the top dead center.
is set so that it descends to bottom dead center and stops. The operating characteristic of the bimetal 29 is that the differential pressure before and after the filter element is 200 mmHg.
Then, when the temperature of fuel F is -50℃, the first contact 25
is set so that it contacts the second contact 26.

On the other hand, the filter cartridge 6 houses a filter element 38 in a case 37 that is screwed onto the mounting shaft 15 of the head cover 5. The outlet side of the filter element 38 is connected to the annular groove 1 of the fuel outlet path 8 through an external space 42 and a port 43.
It is connected to 7.

Next, the operation of this embodiment will be explained.

First, the filter element 38 is not clogged, and the differential pressure between the fuel pressure in the fuel introduction path 7 and the fuel pressure in the fuel outlet path 8, that is, the differential pressure before and after the filter element, is small, for example, 100 mmHg or less. When the value is shown, the piston 32 is held at the bottom dead center by the pressing force of the spring 36. In this position, no matter how the temperature-sensitive actuator 27 operates, the first contact 25 and the second contact 26 do not come into contact with each other. When the flow path resistance in the filter element 38 portion increases due to wax deposition, dust, etc., and the aforementioned differential pressure increases, the piston 32 resists the biasing force of the spring 36 due to the differential pressure. Slide upward to connect the second contact 26 to the first contact 25.
It will move in the direction.

On the other hand, when the temperature of the fuel F is low, the bimetal 29 constituting the temperature-sensitive actuator 27 deforms into a flat shape and moves the first contact 25 downward, so that the second contact 26 rises to some extent. If so, both contacts 25 and 26 come into contact with each other.
As a result, electric power is supplied to the heater 16, and the fuel F flowing inside the heater chamber 13 is heated. As the temperature of the fuel F increases, the bimetal 29
The degree of curvature increases, and the first contact point 25 is moved upward. For example, if the fuel temperature exceeds -5°C, the first contact 25 will rise to the retracted position beyond the movable range of the second contact 26, and the first contact 25 and contact 26 are no longer able to come into contact with each other.

According to this device, power is supplied to the heater 16 only in area A shown in FIG.
will not be passed. That is, area B is
This is a region where the temperature of the fuel F is higher than the set value and the differential pressure across the filter element is lower than the set value, and the heater 16 is not energized in this region, as in the conventional case. Region C is generally a region where the temperature of fuel F is lower than the set value and the differential pressure is lower than the set value. This is a case where no wax is deposited even though the fuel temperature is low because low-temperature fuel is used, and the differential pressure across the filter element shows a small value. The conventional temperature detection method is
Even in such a state, energy is wasted because power is supplied to the heater, but in this device, such wasteful energization of the heater 16 is not performed. Region D is a region where the temperature of the fuel F exceeds the set value and the differential pressure across the filter element is higher than the set value. This shows a case where wax has not been deposited, but the filter element 38 has become clogged with dust or the like due to long-term use. In conventional differential pressure detection systems, power is supplied to the heater even in such a state, but such clogging cannot be resolved by heating the fuel, resulting in wasted energy. In this device, such wasteful energization of the heater 16 is not performed.

Note that the slope of the boundary line a in FIG. 3 can be arbitrarily set by changing the relationship between the temperature and the amount of displacement of the bimetal 29 and the characteristics of the coil spring 36. Further, the left and right positions of the boundary line b can be arbitrarily set by changing the locking position of the piston 32 of the differential pressure actuator 28 and the coil spring 36.

Therefore, if the configuration is like this,
The heater 16 can be energized only in the area A that really requires heating, and the drawbacks of the temperature sensing method and the differential pressure sensing method can be solved at the same time.
Therefore, it is possible to reasonably and effectively control the amount of power consumed, and it is possible to improve the battery charging and discharging balance.

Note that the temperature and differential pressure setting values shown in FIG. 3 are merely examples, and can be arbitrarily set by selecting the operating characteristics of the temperature-sensitive actuator and the differential pressure actuator, as described above.

Furthermore, it goes without saying that the configurations of the temperature-sensitive actuator and the differential pressure actuator are not limited to those of the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] Since the present invention has the above-described configuration, the fuel temperature is low but the differential pressure before and after the filter element is also small, so wax deposition is unlikely to occur in the operating region or differential pressure. It is possible to prevent power from being erroneously supplied to a heater in a region where the fuel temperature is large but wax deposition is unlikely to occur due to the high fuel temperature. Therefore, it is possible to limit the power supply to the heater to the minimum necessary area, effectively suppressing wasteful power consumption, and achieving the effect that battery charging and discharging balance can be improved easily and reliably. .

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which FIG. 1 is a schematic diagram for explaining a route, FIG. 2 is a diagram for explaining the principle, and FIG. 3 is an explanatory diagram for explaining control setting conditions. 4...Fuel filter, 7...Fuel introduction path, 8
...Fuel lead-out path, 25...First contact, 26...
...Second contact, 27...Temperature-sensitive actuator, 2
8... Differential pressure actuator, 38... Filter element.

Claims (1)

[Claims] 1 a heater for heating the fuel to be passed through the filter element of the fuel filter;
a switch mechanism that controls energization to the heater by connecting and separating contacts; a temperature-sensitive actuator that moves the first contact toward the second contact when the fuel temperature is low; and a difference in fuel before and after the filter element. and a differential pressure actuator that moves the second contact toward the first contact as the pressure increases, and the heater is activated only when the fuel temperature is low and the differential pressure of the fuel before and after the filter element is large. A fuel heating device characterized in that it is configured to be able to conduct electricity to.