JP2002256995A - Fuel supplying device and fuel filtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supplying device capable of easily recovering a fuel system. SOLUTION: This device is characterized by comprising a fuel force feed pump which is disposed in a feed passage for feeding diesel fuel from a fuel tank to a fuel injection pump via a fuel filter and is capable of temporarily forcibly feeding the diesel fuel, a temperature operating valve which is disposed in a communicating passage for communicating a return passage for returning return fuel overflowing from the fuel injection pump to the fuel tank with the feed passage in front of the fuel filter and opens the communicating passage at the time of a low temperature when wax is deposited from at least the diesel fuel, a shut-off valve for shutting off the communicating passage when the fuel force feed pump is operated. Because the shut-off valve shuts off the communicating passage when the fuel force feed pump is operated, fuel mixed with air can be prevented from circulating in the fuel system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device or a fuel filtration device provided on a path for supplying diesel fuel to a fuel injection pump of a diesel engine.

[0002]

2. Description of the Related Art Diesel engine (diesel engine)
Has been attracting attention as an organization that excels in suppressing global warming because of its excellent fuel efficiency and low CO2 emissions. Diesel engines usually use diesel fuel or heavy oil, which is a fuel, to increase the pressure with a fuel injection pump, send it to an injection nozzle, spray it into high-temperature, high-pressure air compressed in a cylinder, and burn it to obtain output. . By the way, the fuel injection pumps and injection nozzles used for diesel engines are composed of extremely precise parts, so that the solid content such as dust and the moisture contained in the fuel (diesel fuel) are removed from the fuel filter in front of the fuel injection pump. After sufficient removal of the fuel, the fuel is supplied to those devices. Thus, mechanical abrasion, sticking, rusting, etc. of those devices are prevented.

[0003] However, diesel fuel contains paraffin having a relatively high melting point, and when the temperature becomes low, crystals (wax) of the paraffin precipitate and cause clogging of the fuel filter. If a large amount of such wax accumulates on the fuel filter (especially the element) and causes clogging, the fuel will not flow and the engine will stop. Therefore, it is necessary to prevent the deposition of the wax and ensure the fluidity of the fuel. Become. Therefore, various proposals regarding a fuel heating system have been made in order to prevent wax precipitation. For example, in Japanese Patent Publication No. 5-79823, a heated fuel (return fuel) that overflows and returns from a fuel injection pump via a bimetallic control valve is supplied to a fuel passage (transmission passage) in front of a fuel filter at a low temperature. ). Further, a check valve for preventing a backflow of fuel is provided between the control valve and the feed passage.

Here, the reason why the return fuel is relatively high is that the fuel is heated by frictional heat, compression heat, and the like in the fuel injection pump. Incidentally, although it is different from the above-mentioned object, there is a proposal to adjust the temperature of the fuel by using the heated return fuel to improve the accuracy of the fuel injection amount.
It is disclosed in JP-A-3-126431. However,
In these publications, when running out of fuel (out of gas) or replacing the fuel filter, a large amount of air mixed in the fuel passage is expelled, the fuel system is returned to a normal state, and the diesel engine can be restarted. There is no description of the fuel pump (priming pump) used. On the other hand, Japanese Patent Publication No. 4-31726 discloses a fuel heating apparatus in which the fuel pressure pump, the fuel filter, and the electric heater are integrally provided. The fuel heating device heats the fuel by supplying electricity to the electric heater at a low temperature, avoids wax deposition, and prevents clogging of the fuel filter. However, since an electric heater is used,
The cost is high, and the burden on the battery and the like during energization is large.

[0005]

Therefore, a fuel supply device as shown in FIG. 5 can be considered. This is based on the premise that a fuel pump is provided, and the return fuel from the fuel injection pump is guided to a feed passage before (upstream of) the fuel pump to raise the temperature of the fuel flowing into the fuel filter, thereby increasing the fuel by wax. This is to prevent clogging of the filter. The temperature-operated valve shown in FIG. 5 switches return fuel to a feed passage before the fuel pressure pump at a low temperature where wax is precipitated, while returning the entire amount of the return fuel to the fuel tank at a high temperature. This fuel supply device also includes a check valve for preventing fuel from flowing from the feed passage in front of the fuel pressure feed pump to the return passage.

However, in this fuel supply device, if air is mixed in the fuel passage due to running out of fuel (out of gas) or replacement of a fuel filter element, if the temperature of the fuel is low,
No matter how much the fuel pump is operated to pump fuel,
The fuel mixed with air circulates in the fuel passage through the temperature-operated valve and the check valve, so that air does not escape from the fuel forever. This is because, as shown in FIG. 5, the temperature actuated valve is opened when the temperature is low, and the pressure in the feed passage before it becomes negative due to the operation of the fuel pressure pump, and the check valve is also opened. It is. The present invention has been made in view of such circumstances. In other words, even if air enters the fuel passage due to fuel filter element replacement or running out of fuel, the fuel system can be easily returned and stable fuel supply can be achieved by avoiding clogging of the fuel filter by wax. It is an object of the present invention to provide a fuel supply device or a fuel filtration device.

[0007]

In order to solve this problem, the present inventor has provided a fuel pump to prevent the deposition of wax by heating the fuel in front of the fuel filter using return fuel. On the premise, when the fuel pump is operated, the idea of shielding the return fuel passage led before the fuel filter was conceived, and the fuel supply device or the fuel filtration device of the present invention was developed. 1) That is, the fuel supply device of the present invention described in claim 1 is provided in a transmission passage for sending diesel fuel from a fuel tank to a fuel injection pump through a fuel filter, and is capable of temporarily pumping the diesel fuel. A fuel supply pump, a return passage for returning return fuel overflowing from the fuel injection pump to the fuel tank, and a fuel filter. A temperature-operated valve disposed in a communication passage communicating with the front delivery passage and opening the communication passage at a low temperature at which wax precipitates from the diesel fuel; and a communication passage when operating the fuel pressure delivery pump. And a shielding valve for shielding the air.

At a low temperature when the temperature-operated valve is opened, the return fuel heated by the fuel injection pump is guided to the feed passage before the fuel filter through the communication passage, and the temperature of the fuel is raised to clog the fuel filter with wax. Can be prevented as described above. By the way, in the present invention, when the fuel pump is operated, the communication path for guiding the return fuel from the return path to the supply path can be shielded by the shield valve. Therefore, even if the fuel pump is operated while air is mixed in the fuel passage due to element replacement of the fuel filter, running out of fuel, or the like, the return fuel containing air is not returned to the transfer passage again. Does not circulate in the fuel passage, so that the fuel system can be easily returned.

(2) The fuel filter according to the present invention is provided in a feed passage for sending diesel fuel from a fuel tank through a fuel filter to a fuel injection pump, and is provided in front of the fuel injection pump. A fuel filter that filters diesel fuel, a fuel pump that is disposed in the feed passage and that can temporarily pump the diesel fuel,
The communication passage is provided in a communication passage which communicates a return passage for returning return fuel overflowing from the fuel injection pump to the fuel tank and the transmission passage in front of the fuel filter, at least at a low temperature at which wax is precipitated from the diesel fuel. , A shut-off valve for shutting off the communication passage when the fuel pump is operated, a bottomed cylindrical lower housing provided with the fuel filter, the fuel pump and the temperature-operated valve And an upper housing provided in the opening of the lower housing, the upper housing having the shielding valve.

In the above-described fuel supply device, the fuel pump, the temperature-actuated valve, and the shut-off valve may be integrally formed or may be provided separately, or the fuel filter may be an essential component. Not. On the other hand, in this fuel filtering device, a fuel filter is provided in a lower housing, and a fuel pump, a temperature actuated valve, and a shutoff valve are integrally provided in an upper housing. With such a configuration, the size of the fuel filtration device can be reduced. Further, when the fuel filter accommodates the replaceable element in the lower housing, the element can be easily replaced by disassembling the lower housing and the upper housing. Further, it is more preferable that a sedimenter capable of separating water contained in the diesel fuel is provided at the bottom of the lower housing.

(3) In any of the above-described fuel supply device and fuel filter device, the following can be said. That is, it is preferable that the temperature-operated valve is a bimetal valve that closes the communication path at a higher temperature than at a low temperature. By using a bimetal valve as the temperature-operated valve, the temperature-operated valve can be configured with low cost and high accuracy. Further, since the communication passage is closed at a high temperature, almost all the heated return fuel returns to the fuel tank, and the return fuel does not circulate through the fuel injection pump. Therefore, since the fuel injection pump is cooled by the fuel sent from the fuel tank through the feed passage, overheating of the fuel injection pump is also prevented.

Further, the communication passage communicates with a feed passage between the fuel filter and the fuel pressure feed pump disposed in front of the fuel filter.
It is preferable that the valve be a valve that closes the communication passage when the pressure of the inside of the delivery passage becomes positive due to the operation of the fuel pressure delivery pump (see FIG. 1). When the fuel pump is operated, the inside of the feed passage downstream therefrom becomes positive pressure. When the shield valve is configured by a valve that closes the communication passage at the time of the positive pressure, the shield valve can have a simple structure. For example, if the shut-off valve is
The communication path is lightly biased from the transmission path toward the return path, and the communication path can be closed by contacting a valve seat provided in the communication path. Note that the "lightly" bias means that during normal operation of the diesel engine (when the fuel pump is not operating), the shield valve is opened by the negative pressure acting on the feed passage downstream of the fuel pump. Things. However, providing such an urging force enables stable support of the valve. Although the fuel pump can be an electric pump, the use of the fuel pump is limited.For example, a simpler structure such as a manual pump using a diaphragm should be used. Is preferred.

FIG. 1 conceptually shows an example of such a fuel system system configuration according to the present invention. FIG. 1 shows a state in which the fuel pump is operated at a low temperature. Despite the temperature-operated valve being open, the discharge pressure (positive pressure) of the fuel pump acts on the shut-off valve, so that the shut-off valve closes the communication passage. For this reason, return fuel mixed with air is returned to the fuel tank without flowing into the feed passage. The fuel pump shown in FIG. 1 is a manual pump using a diaphragm, and has check valves at both the suction port and the discharge port. Although the above description has been made on the premise that the temperature operated valve and the shutoff valve are independent valves, it is also possible to configure those valves with one electromagnetic valve. For example, an electromagnetic valve that opens the communication passage at the time of the low temperature and closes the communication passage at the time of the high temperature to operate the fuel pressure pump may be closed regardless of the temperature of the diesel fuel.

[0014]

Next, the present invention will be described more specifically with reference to embodiments according to the present invention. FIG. 2 shows a fuel filtration device 100 according to a first embodiment of the present invention. The fuel filtering device 100 is a more specific example of the fuel supply device of the present invention. The fuel filtering device 100 includes a priming pump 110, a temperature switching valve 120, a fuel filter 130, and a segmenter 140. The priming pump 110 and the temperature switching valve 120 are housed in an upper housing 150, and the fuel filter 130 and the segmenter 140 It is housed in the lower housing 160. The priming pump 110 corresponds to the fuel pressure pump according to the present invention. When the diaphragm 111 is manually swung up and down by the knob 112, the diesel fuel is pumped from the suction port 113 to the discharge port (not shown). Things. In addition, the suction port 113 and the discharge port are provided with check valves that allow the intake and discharge of fuel, respectively.

The temperature switching valve 120 is a bimetal valve 1
21, a check valve 122 and a valve housing 123 for accommodating them.
And the check valve 122 correspond to the temperature-operated valve and the shut-off valve in the present invention, respectively. An enlarged view of the temperature switching valve 120 is shown in FIG. As can be seen from FIG. 3, the return fuel is provided in the center of the valve housing 123 in the return passage 12.
A communication path 124 is formed to guide the communication path 124 from the communication path 5 to the transmission path 126. A communication port 127 communicating with the communication path 124 is opened and closed by the bimetal valve 121.
Note that this opening / closing position may be used as the holding body 121a below the bimetal valve 121. This bimetal valve 1
Numeral 21 closes the communication port 127 at or above the cloud point of the return fuel (light oil). Since the cloud point of light oil differs depending on the grade of light oil, it is set according to the specifications of the diesel engine. Note that the cloud point of light oil is a temperature at which wax starts to precipitate from light oil. The reason why the opening / closing switching temperature of the bimetal valve 121 is set to be higher than the cloud point is as follows. What the bimetal valve 121 directly senses is the temperature of the return fuel, and there is a deviation from the temperature of the fuel sent to the fuel filter 130. By providing a margin for the operating temperature, hunting and the like of the check valve 122 can be prevented and stable operation can be performed. Thus, the bimetal valve 12
By providing a margin at the first operating point, clogging of the fuel filter 130 by wax can be stably avoided, and overheating of the fuel injection pump can be prevented.

A nipple 125a is press-fitted into an inflow port of the return passage 125, and can be connected to a fuel injection pump (not shown) by an oil-resistant rubber hose. A nipple 125b is press-fitted also into a discharge port of the return passage 125, and can be connected to a fuel tank (not shown) by an oil-resistant rubber hose. It should be noted that the flow direction described above is also valid even if the flow direction is reversed. The check valve 122 is disposed downstream of the bimetal valve 121, and is urged from the downstream to the upstream by a coil spring 122a having a small spring constant with the holding body 121a of the bimetal valve 121 as a valve seat. The coil spring 122a is supported by a support 150b, and the support 150b is provided with a notch on the outer peripheral side so that fuel can flow from the communication passage 124 to the feed passage 126. The valve housing 123
Are oil-tightly fitted into a cylindrical recess of the upper housing 150 with an O-ring 128 interposed therebetween.

The fuel filter 130 has an element 131 formed of a bellows-like filter paper in a substantially cylindrical shape, which is accommodated in a lower housing 160 having a substantially bottomed cylindrical shape. Then, the diesel fuel sent from the feed passage 126 flows into the inside through the outer peripheral side and the bottom side of the element 131, and the filtered fuel is sent from the outlet port 132 provided on the upper side to the fuel injection pump. . At this time, the temperature switching valve 12
The zero operation prevents the wax from accumulating on the element 131 because the temperature of the fuel is above the cloud point of light oil.

The segmenter 140 is provided in the lower housing 1.
It is provided on the bottom side of 60 and sediments and separates water contained in diesel fuel. The segmenter 140 includes a float type water level sensor 141 and a drain cock 142. When the separated water exceeds a set height, the float type water level sensor 141 outputs an ON signal and turns on a warning light (not shown). Then, the driver or the like who recognizes the situation can remove moisture in the segmenter 140 by loosening the drain cock 142.

FIG. 2 shows the flow of fuel in the fuel filter 100.
Or, it will be described with reference to FIG. First, during normal operation, fuel flows from the fuel tank → the feed passage 116 → the priming pump 110 (flow →). Next, it flows from the priming pump 110 to the feed passage 126 through the back side in FIG. 2 (flow →). Next, the fuel flows through the fuel filter 130 to the fuel injection pump (flow →→). Thereafter, the fuel injection pump returns to the fuel tank through the return passage 125 (flow →). Here, when the temperature of the return fuel flowing through the return passage 125 is relatively low, the bimetal valve 121 is opened, and
The check valve 122 is also open because 26 is also in a negative pressure state. As a result, a part of the return fuel flows into the feed passage 126 through the communication passage 124 to increase the temperature of the fuel flowing in the feed passage 126, thereby preventing the deposition of wax.

When air enters the fuel passage due to replacement of the element 131 or lack of gas, the manual button of the priming pump 110 is pressed up and down a predetermined number of times. At this time, since the engine is stopped, that is, the feed pump of the fuel injection pump is stopped, the inside of the feed passage 126 has a positive pressure. Therefore, the check valve 122
, A force acts on the side that closes the communication port 127, and the check valve 122 blocks the flow of the return fuel through the communication passage 124. As a result, the entire amount of the fuel that has exited the fuel injection pump flows into the fuel tank through the return passage 125, and the fuel mixed with the air does not return to the feed passage 126 again. Therefore, by operating the priming pump 110 a predetermined number of times, the fuel mixed with air is returned to the fuel tank, and the fuel passages are filled with fuel mixed with no air.

Next, a fuel supply device according to another embodiment of the present invention will be described. The fuel supply device includes a priming pump 110, a fuel filter 130, and a temperature switching valve 120, as in the fuel filter device 100 described above.
Are not divided, but are appropriately divided.
FIG. 4 shows a temperature switching valve 220 as a main part thereof. The temperature switching valve 220 has the same basic configuration and function as the temperature switching valve 120 described above. That is, the bimetal valve 221, the check valve 222, the lower valve housing 260 that houses them, and the bimetal valve 2
21 comprises an upper valve housing 250 that sandwiches the lower valve housing 21 with the lower valve housing 260 to form a return passage 225 and a communication passage 224. Here, the bimetal valve 221 and the check valve 222 correspond to the temperature actuated valve and the shutoff valve, respectively, in the present invention.

A nipple 250a is formed integrally with the inflow port of the return passage 225, and can be connected to a fuel injection pump (not shown) by an oil-resistant rubber hose. A nipple 250b is formed integrally with the discharge port of the return passage 225 so that the nipple 250b can be connected to a fuel tank (not shown) with an oil-resistant rubber hose. The check valve 222 is a bimetal valve 221
, And is urged from the downstream side to the upstream side by a coil spring 222a having a small spring constant with the holding body 221a of the bimetal valve 221 as a valve seat. The coil spring 222a is supported by a support portion 260b of the lower valve housing 260. The support portion 260b of the lower valve housing 260 is provided with a notch on the outer peripheral side so that fuel can flow from the communication passage 224 to the transmission passage 226. It has become. The flow of the fuel is the same as in the case of the above-described fuel filtering device 100 shown in FIG. 3, and the flow direction and reference numerals are also shown in FIG. 4 corresponding to FIG.

[0023]

As described above, according to the fuel supply device or the fuel filtration device of the present invention, even when the fuel pump is operated in a state where air is mixed in the fuel passage due to replacement of the fuel filter or running out of fuel, etc. Since the shutoff valve shields the communication passage, the return fuel containing air does not return to the feed passage again, thereby preventing the fuel from circulating in the fuel system.

Further, the provision of the fuel pressure pump facilitates the return of the fuel system, and at the time of low temperature, returns the return fuel to the feed passage in front of the fuel filter, thereby preventing the fuel filter from being clogged by the wax. . Furthermore, in the fuel filtration device of the present invention, since the fuel filter and the like are integrally formed, the entire device can be made compact.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration example of a fuel system according to the present invention.

FIG. 2 is an overall view showing a fuel filtration device according to an embodiment of the present invention.

FIG. 3 is an enlarged view of a temperature switching valve according to the embodiment.

FIG. 4 is an enlarged view showing a temperature switching valve of the fuel supply device according to the embodiment of the present invention.

FIG. 5 is a diagram showing a system configuration of a fuel system studied during the development of the present invention.

[Explanation of symbols]

Reference Signs List 100 fuel filtering device 110 priming pump (fuel pressure pump) 120 temperature switching valve 121 bimetal valve (temperature operated valve) 122 check valve (shielding valve) 130 fuel filter 140 segmenter 150 upper housing 160 lower housing

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 55/00 F02M 55/00 B (72) Inventor Hiroshi Morishita 1-1-1 Showa-cho, Kariya-shi, Aichi Pref. F-term in DENSO (reference) 3G066 AA07 AB02 BA00 BA53 CB16 CC68S CD11 CD12 CE00

Claims (3)

[Claims] A fuel pump provided in a feed passage for sending diesel fuel from a fuel tank to a fuel injection pump through a fuel filter and capable of temporarily pumping the diesel fuel, and overflowing from the fuel injection pump. A temperature-operated valve disposed in a communication path connecting a return path for returning return fuel to the fuel tank and the transmission path in front of the fuel filter, and opening the communication path at least at a low temperature at which wax precipitates from the diesel fuel. And a shut-off valve for shutting off the communication passage when operating the fuel pump. 2. The communication passage communicates with a transmission passage between the fuel filter and the fuel pressure pump disposed in front of the fuel filter. 2. The fuel supply device according to claim 1, wherein the valve is a valve that closes the communication passage when the inside of the communication passage becomes a positive pressure by operating. 3. A fuel filter disposed in a passage for sending diesel fuel from a fuel tank through a fuel filter to a fuel injection pump for filtering the diesel fuel in front of the fuel injection pump; A fuel pump capable of temporarily pumping diesel fuel, a return passage for returning return fuel overflowing from the fuel injection pump to the fuel tank, and a communication passage communicating the transfer passage in front of the fuel filter. A temperature-operated valve provided to open the communication passage at a low temperature at which wax precipitates from at least the diesel fuel; a shut-off valve for shielding the communication passage when operating the fuel pump; and a bottom having the fuel filter. A cylindrical lower housing, the fuel pump, the temperature-operated valve, and the shut-off valve; Fuel filter and wherein the upper housing provided in the hole, in that it consists of.