JP5333424B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply device equipped to supply fuel in a fuel tank to an internal combustion engine, and more particularly, to an internal combustion engine having a fuel cooler for preventing high temperature of fuel recirculated from the internal combustion engine into the fuel tank. The present invention relates to a fuel supply apparatus.

In an internal combustion engine, for example, a diesel engine (hereinafter simply referred to as an engine), fuel in a fuel tank is supplied through a supply line, and surplus fuel that has not been consumed in the fuel injection device is returned to the fuel tank through a return line. A fuel supply device is provided.
By the way, an engine with a direct injection type common rail fuel injection device (DI common rail type diesel engine) usually has a higher return fuel temperature than an engine with a conventional sub chamber type fuel injection device (IDI diesel engine). It has been known. Furthermore, the temperature of the fuel supplied to the high-pressure fuel pump of the engine needs to be kept below the required fuel temperature of the high-pressure fuel pump. For this reason, the fuel is cooled by means such as mounting a fuel cooler on the return pipe (return fuel line).

  For example, in the conventional fuel supply device, as shown in FIG. 8, the fuel in the fuel tank 120 is supplied to the fuel injection device 110 provided in the engine 100 via the supply line 140 including the filter 130. The fuel injection device 100 here includes a high-pressure pump 150 that is driven in conjunction with engine driving, and a fuel injection valve 160 connected to the high-pressure pump 150 injects high-pressure fuel into a combustion chamber (not shown) in the engine body. Thus, the output of the engine 100 is generated.

  Excess fuel that has not been consumed by the fuel injection device 100 is returned to the fuel tank 120 via a return line 180 including a thermostat 190 and a fuel cooler 170. At this time, since the fuel cooler 170 in the return pipe line 180 cools the surplus fuel, the fuel that is once returned to the fuel tank and supplied to the engine side again is prevented from being excessively heated. For this reason, it can be suppressed below the required fuel temperature on the high-pressure fuel pump side, and in the case of a gasoline engine, it is possible to suppress the occurrence of vapor or the dilution of the air-fuel ratio due to the generation of vapor in the fuel due to fuel vaporization. Is prevented from falling.

  On the other hand, when the ambient temperature is low, the thermostat 190 between the high pressure pump 150 and the fuel cooler 170 is switched, whereby the fuel in the return line 180 upstream of the thermostat 190 passes through the bypass path 200 downstream of the thermostat 190. The fuel cooler 170 is bypassed and returned to the fuel tank 120. Here, excessive fuel (low-temperature light oil) can be prevented from being excessively cooled by the fuel cooler 170, and the excessive fuel is supercooled and falls below the wax precipitation temperature, or the fuel temperature in the fuel tank 120 is low. The melt temperature required to melt the wax deposited in the light oil cannot be secured, and the wax component contained in the fuel precipitates, resulting in a rapid increase in flow resistance, resulting in insufficient fuel supply to the engine. I try to prevent the occurrence of the situation.

An example of a fuel supply device in which surplus fuel from a fuel injection device of an engine is cooled by a fuel cooler provided in a return pipe and then returned to a fuel tank is disclosed in JP-A-2004-162538. Is disclosed.
Here, a thermostat for switching the flow path is provided at the upstream branch of the fuel cooler, and when the temperature of the surplus fuel is high, the fuel flows to the fuel cooler to suppress excessively high temperature of the fuel, and when the temperature is low Fuel is allowed to flow through the bypass pipe to prevent overcooling of the fuel, thereby preventing the precipitation of wax contained in the fuel and the occurrence of insufficient fuel supply to the engine.

  Further, the fuel supply device disclosed in the cited document 2 (Japanese Patent Laid-Open No. 2003-56344) includes an engine cooling device for a construction machine in which an engine radiator, an oil cooler, an intercooler, and a fuel cooler are integrally arranged. Is disclosed. Here, a thermo valve is provided on the return line of the fuel injection pump 17 on the upstream side of the fuel cooler. When the fuel from the fuel injection pump is at a low temperature, the thermo valve bypasses the fuel cooler and returns it to the fuel tank. Prevents overcooling.

JP 2004-162538 A JP 2003-56344 A

As described above, in the conventional DI common rail type diesel engine, when the ambient temperature is relatively high, for example, as shown in FIG. 8, the surplus fuel is cooled by the fuel cooler 170 and then returned to the fuel tank 120. The fuel supplied to the engine 100 again is prevented from being excessively heated, and is kept below the required fuel temperature on the high-pressure fuel pump side to prevent a decrease in engine output.
On the other hand, when the ambient temperature is low, for example, as shown in FIG. 8, the thermostat 190 upstream of the fuel cooler 170 detects a decrease in the fuel temperature, and in response to this, the fuel is caused to flow through the bypass passage 200 and the excess by the fuel cooler. Avoids cooling, prevents excessive fuel (low-temperature gas oil) from being cooled excessively, and suppresses the occurrence of insufficient fuel supply to the engine due to a rapid increase in flow resistance accompanying the precipitation of the wax component contained in the fuel. .

However, in the fuel supply devices shown in the above cited references 1 and 2 and FIG. 8, the temperature of the surplus fuel at the position before passing through the fuel cooler, which is the upstream position of the fuel cooler, is detected by the thermostat, Cooling prevention control is performed.
For this reason, in the conventional apparatus, switching is performed between flowing the surplus fuel to the fuel cooler according to the temperature of the surplus fuel that has reached the thermostat from the high-pressure pump or maintaining the heat retaining property by flowing to the bypass passage. It does not consider how much the later fuel temperature decreases due to the influence of the ambient temperature.

  That is, in the fuel supply devices shown in the cited documents 1 and 2 and FIG. 8, when traveling in a cold region, for example, the temperature of the surplus fuel when it reaches the thermostat from the high-pressure pump 1 switches to the bypass path. Even if it is not necessary, if the temperature of the surplus fuel after passing through the fuel cooler is excessively lowered by the outside air, the temperature becomes lower than the wax deposition temperature, or the fuel temperature in the fuel tank is lowered and the fuel is cooled. The melting temperature necessary for melting the wax precipitated therein cannot be ensured, and accordingly, it is impossible to prevent the occurrence of a situation in which insufficient fuel supply to the engine occurs due to a rapid increase in flow resistance.

  The present invention has been made on the basis of the above problems, and the object is to melt the wax precipitated in the fuel in the tank when the return fuel is excessively cooled by the fuel cooler. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can reliably prevent the occurrence of a situation in which the engine cannot be supplied and the filter is clogged, resulting in insufficient fuel supply to the engine.

The invention of claim 1 of the present application is a supply line for supplying fuel from a fuel tank to a fuel injection device of an engine, and a return line for cooling surplus fuel from the fuel injection device by a fuel cooler and returning it to the fuel tank. Depending on the temperature of the fuel that passes through the junction, and a bypass path that causes the fuel flowing through the return pipe to flow around the fuel cooler by bypassing the fuel cooler to the downstream junction from the upstream branch of the fuel cooler Flow path switching means for communicating either the return pipe line or the bypass path with the fuel tank, wherein the flow path switching means is configured such that the temperature of the fuel passing through the junction is higher than the first temperature on the high temperature side. A thermostat for switching the fuel cooler and the fuel tank to communicate with each other when the temperature is high, and to switch the fuel passage between the bypass passage and the fuel tank when the fuel temperature is lower than the first temperature on the low temperature side. And a surplus fuel control means for controlling an amount of surplus fuel from the fuel injection device, wherein the surplus fuel control means is configured to control the surplus fuel control means when the fuel temperature falls below a low temperature side second temperature lower than the low temperature side first temperature. The amount of surplus fuel is increased .

The invention of claim 2 of the present application is the fuel supply device for an internal combustion engine according to claim 1 , wherein the bypass path is held in a storage box supported at the lower part of the vehicle body.

According to a third aspect of the present invention, in the fuel supply device for an internal combustion engine according to the second aspect , the bypass path is held in a storage box supported at a lower part of a vehicle body together with the fuel cooler.

According to a fourth aspect of the present invention, in the fuel supply apparatus for an internal combustion engine according to the third aspect , the storage box includes a shutter for guiding outside air to the fuel cooler, and the control means controls the shutter so that the fuel temperature is the high temperature. When it exceeds the first temperature on the side, it switches to the open state, and when it falls below the second temperature on the low temperature side, it switches to the closed state.

The invention of claim 5 of the present application is the internal combustion engine fuel supply apparatus according to any one of claims 1 to 4 , further comprising output control means for controlling an output generated by the internal combustion engine, wherein the output control means comprises: When the fuel temperature exceeds the high temperature side second temperature that is higher than the high temperature side first temperature, the generation of a high output exceeding the predetermined value from the internal combustion engine is limited.

According to the first aspect of the present invention, the return pipe and the bypass are switched according to the temperature of the fuel passing through the junction, that is, the actual temperature of the fuel returning to the fuel tank, and the temperature of the fuel in the fuel tank is more accurately controlled . At this time, by switching the thermostat, if the temperature of the fuel passing through the junction is higher than the first temperature on the high temperature side, the fuel is cooled by the fuel cooler, and it is suppressed from reaching the required fuel temperature on the high pressure fuel pump side. To prevent a decrease in engine output. On the other hand, when the temperature is lower than the first temperature on the low temperature side, the fuel is returned to the fuel tank from the bypass passage, and the wax is prevented from depositing in the fuel, and the filter of the filter due to the wax is suppressed. It is possible to reliably prevent a supply shortage from occurring. In particular, when the fuel temperature falls below the second temperature on the low temperature side, the amount of high-temperature surplus fuel returned to the fuel tank is increased, thereby preventing the fuel temperature in the fuel tank from being excessively cooled.

In the invention of claim 2 , since the bypass path is held in the storage box, the fuel temperature is a low temperature lower than the first temperature on the low temperature side, and when returning the fuel from the bypass path to the fuel tank, This prevents the fuel temperature from dropping and more reliably suppresses wax precipitation in the fuel due to overcooling of the fuel, keeping the fuel in the tank above the temperature necessary to melt the wax, and Clogging and insufficient fuel supply to the engine can be reliably prevented.

In the invention of claim 3 , since both the bypass passage and the fuel cooler are held in the storage box, in addition to the same effect as the fuel supply device for the internal combustion engine according to claim 2 , the bypass passage and the fuel cooler are provided. Both can prevent contact with foreign matter on the road surface side during traveling and ensure durability.

According to a fourth aspect of the present invention, in addition to the same effect as the fuel supply device for the internal combustion engine according to the third aspect , the shutter provided in the housing box is opened when the fuel temperature exceeds the first temperature on the high temperature side. Control the outside air to the fuel cooler and suppress excessive temperature rise of the fuel flowing into the fuel tank. Conversely, the fuel temperature is lower than the first temperature on the low temperature side and the flow path is switched to the bypass path side. However, when the temperature is still low, that is, when the temperature is lower than the second temperature on the low temperature side, the shutter is closed to suppress the cooling function of the fuel cooler, and overcooling of the fuel flowing into the fuel tank from the bypass path side can be prevented.

According to the fifth aspect of the present invention, when the fuel temperature is higher than the second temperature on the high temperature side, the engine temperature is controlled to suppress the fuel temperature of the surplus fuel and prevent the fuel temperature from excessively rising.

1 is an overall configuration diagram of a fuel supply device for an internal combustion engine as one embodiment of the present invention. FIG. 2 is an overall schematic diagram of the fuel supply device for the internal combustion engine of FIG. 1. FIG. 2 is a diagram showing fluctuation characteristics of fuel temperature at a plurality of locations in the fuel supply device for the internal combustion engine of FIG. 1. It is a whole block diagram of the fuel supply apparatus of the internal combustion engine which is other embodiment of this invention. 6 is a flowchart of a fuel flow path switching processing routine used in the fuel supply device for the internal combustion engine of FIG. 4. FIG. 6 is an enlarged partial cutaway front view of a return pipe used in a fuel supply device for an internal combustion engine according to another embodiment of the present invention, a fuel cooler around it, a bypass pipe, a three-way switching valve, and a fuel cooler shutter. It is a flowchart of the fuel flow-path switching process routine used with the fuel supply apparatus of the internal combustion engine of FIG. It is a whole schematic diagram of the fuel supply device of the internal combustion engine of the conventional device.

Hereinafter, the fuel supply device M1 for an internal combustion engine according to the first embodiment of the present invention will be described.
FIG. 1 shows an overall configuration of a fuel supply device M1 for an internal combustion engine according to the present invention, and FIG.
A fuel supply device M1 for the internal combustion engine includes a diesel engine (hereinafter referred to as an engine) 1 as an internal combustion engine, a fuel tank 2 for storing fuel supplied to the engine 1, and fuel from the fuel tank 2 for the engine 1. As shown in FIG. 2, the fuel supply path R1 is schematically shown as a supply line 4 for supplying the fuel injection apparatus 3 and a return line 5 for returning surplus fuel from the fuel injection apparatus 3 to the fuel tank 2. It is formed so as to form an annular shape.

Furthermore, the fuel supply device M1 for the internal combustion engine cools the fuel that is recirculated from the engine 1 to the fuel tank 2 and the fuel flowing through the return pipe 5 from the upstream branch 7 of the fuel cooler 6. A bypass pipe line 9 for bypassing the fuel cooler 6 to flow to the merging section 8 on the downstream side and a flow path switching means 11 provided in the merging section 8 are provided.
The flow path switching means 11 includes a thermostat 45 provided in the junction 8;
The temperature sensor 13 for detecting the temperature of the fuel passing through the junction 8 and the switching state of the thermostat 45 (the output of a limit switch (not shown)) are detected, and the radiator shutter, the fuel cooler shutter, the engine excess fuel increase / decrease control, the engine And control means 14 for controlling output limitation.

A fuel injection device 3 shown in FIG. 1 includes a high-pressure fuel pump 15 that is linked to the engine 1, a common rail 16 that is disposed along the longitudinal direction of the engine body 101 and that is supplied with high-pressure fuel from the high-pressure fuel pump 15, and is not illustrated. Each cylinder for injecting fuel into the combustion chamber of each cylinder and a fuel injection valve 17 arranged oppositely. The fuel in the fuel tank 2 supported on the vehicle body side 2 is directly sucked into the high-pressure fuel pump 15 supported by the engine body 101 via the supply line 4 including the filter 30.
Further, as shown by a two-dotted line in FIG. 1, in the case of the specification with the low-pressure fuel pump 18, the fuel is sucked from the electric low-pressure fuel pump 18 through the supply line 4 provided with the filter 30, It is sucked and supplied by the high-pressure fuel pump 15.

Here, the pressure of the fuel supplied by the pump operation of the high-pressure fuel pump 30 is increased, the high-pressure fuel is supplied to the fuel injection valve 17 of each cylinder via the common rail 16, and the pressure is increased by the fuel injection valve 17 controlled by the control means 14. Fuel is injected into each opposing combustion chamber. In addition, the code | symbol 181 in FIG. 1 shows the filter in a tank. Further, a reference numeral 19 indicated by a two-point difference line is a pressure regulating valve for adjusting the low pressure fuel pressure in the supply pipe line 4 to be a predetermined value used in the specification with the low pressure fuel pump 18.
A fuel pressure sensor 21 that detects fuel pressure is provided at one end of the common rail 16, and a fuel pressure adjustment valve 20 is provided at the other end. A return pipe that returns excess fuel from the common rail 16 to the fuel tank 2 is provided in the fuel pressure adjustment valve 20. Path 5 is connected. Here, in accordance with the fuel pressure signal of the fuel pressure sensor 21, the control means 14 controls the drive of the high-pressure fuel pump 15, the fuel pressure adjusting valve 20, and the surplus fuel amount so as to maintain the common rail pressure at a predetermined value.

  The return pipe 5 is a flow path for returning surplus fuel from the common rail 16 to the fuel tank 2, and in the middle thereof, the injection pump-side return pipe 22 that causes the leak fuels on the fuel injection valves 17 and the high-pressure fuel pump 15 to flow. And the surplus fuel flows to the downstream branching portion 7 side. The branch portion 7 of the return pipeline 5 is formed so that the upstream side of the bypass pipeline 9 branches and extends, and the junction 8 is formed so that the downstream side of the bypass pipeline 9 merges. A fuel cooler 6 is disposed between the branching portion 7 and the merging portion 8 of the return pipe 5, and a straight bypass pipe 9 is provided in parallel with the fuel cooler 6.

  The main part of the bypass line 9, the fuel cooler 6, and the thermostat 45 are all housed in a housing box 24 fastened to the floor plate 23 at the bottom of the vehicle body. The storage box 24 may be a reinforced plastic such as glass fiber reinforced plastic (FRP), and may be formed of a steel plate. By forming the attachment portion of the accommodation member on the inner wall of the accommodation box 24, the accommodation member can be easily attached and supported on the vehicle body side. Moreover, contact with foreign matter on the road surface side during traveling can be prevented, and durability can be ensured.

In particular, the fuel cooler 6 is disposed so as to face the air inlet 25 provided on the side wall of the storage box 24, and is formed so that the fuel can be easily radiated by the flow of traveling air from the air inlet toward the exhaust port (not shown). Is done. On the other hand, the bypass line 9 is provided in a shape part that does not interfere with the traveling wind from the air guide port 25 toward the exhaust port (not shown), for example, a part closest to the upper wall of the storage box 24. In this way, heat dissipation of the fuel flowing through the bypass pipe 9 is suppressed.
Here, the return pipe 5 has a configuration in which a bypass pipe 9 and a fuel cooler 6 pipe are arranged in parallel between the branch portion 7 and the return pipe 5, and in particular, a thermostat 45 is arranged in the junction 8. Take.

The thermostat 45 constituting the main part of the flow path switching means 11 includes a casing 46 fixed to the inner wall of the storage box 24, a valve body 48 slidably supported in a valve sliding hole 47 in the casing 46, and a valve body A temperature sensing portion 49 forming a thermostat main body disposed between one end of 48 and the upper end portion of the storage box 24; and a return spring 51 disposed between the other end of the valve body 48 and the lower end portion of the storage box 24. With.
The storage box 24 is formed with a bypass port h1 that communicates with the bypass conduit 9, a cooler port h2 that communicates with the conduit of the fuel cooler 6, and an inflow port h3 that is disposed at a position facing these. The port h3 communicates with the fuel flow chamber 471 of the valve sliding hole 47 through the communication path rh. Further, the fuel flow chamber 471 communicates with the downstream return pipe 501 from a portion away from the communication path rh.

The valve sliding hole 47 is formed long in the vertical direction of the storage box 24, and the valve body 48 fitted therein is divided into two sections, upper and lower valve parts 481 and 482, and the outer cylinder of the temperature sensing part 49 is formed at the upper end. The member 491 is integrally coupled, and the inner cylinder member 492 fitted in the center of the outer cylinder member 491 is integrally coupled to the inner wall of the valve sliding hole 47.
In the temperature sensing portion 49, the outer cylinder member 491 expands and contracts with respect to the inner cylinder member 492 in accordance with the temperature of the fuel flowing in the fuel flow chamber 471, and the valve body 48 integrated with the outer cylinder member 491 returns accordingly. It slides up and down against the elastic force of the spring 51. Here, when the outer cylinder member 491 is reduced and displaced with respect to the inner cylinder member 492 and is held at the first position d1 at the upper end, the lower valve portion 482 communicates the bypass port h1 with the inflow port h3 and closes the cooler port h2. Keep state. On the other hand, when the outer cylinder member 491 is extended and displaced with respect to the inner cylinder member 492 and is held at the second position d2 at the lower end, the cooler port h2 is communicated with the inflow port h3 by the upper valve portion 481, and the bypass port h1 is closed. Hold.

Next, the operation of the fuel supply device M1 for the internal combustion engine as the first embodiment in which such a thermostat 45 is arranged in the junction 8 to constitute the flow path switching means 11 will be described.
Here, before the engine 1 warms up in the early stage of traveling of the vehicle, the temperature of the fuel is relatively low (low temperature side first temperature Tfc), and the thermostat 45 has a temperature sensing portion whose fuel temperature in the fuel flow chamber 471 is high. Since it is low, it contracts and is held at the first position d1 at the upper end, and the lower valve part 482 communicates the bypass port h1 and the inflow port h3, and guides fuel to the fuel tank 2 side from the bypass line 9 that maintains the heat-retaining state. .

  In this state, the temperature of the fuel is suppressed from being lowered, and an excessive decrease in the temperature of the fuel flowing into the fuel tank 2 is suppressed. For example, even when the vehicle is traveling in a cold region, the reference symbol L1 indicates the fuel temperature indicated by the symbol Lb1 in FIG. It can be displaced early to the temperature state on the temperature raising side indicated by. Thereby, the temperature of the fuel flowing into the fuel tank 2 is maintained at a relatively high temperature than the low temperature side second temperature (supercooling temperature) Tc, and precipitates such as wax can be suppressed and the precipitates can be melted. The clogging of the filters 181 and 30 and the malfunction of the low-pressure fuel pump 18 can be prevented, and the occurrence of insufficient fuel supply to the engine can be reliably prevented.

  On the other hand, assuming that the vehicle is in an environment range lower than the high temperature side first temperature Tf2 at the beginning of travel (for example, the temperature range of Ln), the thermostat 45 is held at the first position d1, and the lower valve portion 482 is connected to the bypass port h1 and the inflow port. It is assumed that h3 is communicated and the fuel is led from the bypass pipe 9 to the fuel tank 2 side. From this state, it is assumed that the vehicle enters a high temperature region and travels in an environmental region that exceeds the high temperature side first temperature Tf2. In this case, as the fuel temperature rises, the outer cylinder member 491 extends and displaces with respect to the inner cylinder member 492 of the temperature sensing section 49, and the mostat 45 switches from the first position d1 to the second position d2. Thereby, the cooler port h2 communicates with the inflow port h3 by the upper valve part 481, and the state which closes the bypass port h1 is hold | maintained.

In this state, the fuel is cooled by the fuel cooler 6 to suppress the temperature rise of the fuel and flow into the fuel tank 2. In this case, for example, even if the temperature fluctuation on the high temperature traveling region side indicated by the symbol Lh in FIG. 3 is originally performed, the fuel is reliably cooled by the fuel cooler 6 and guided to the fuel tank 2 side. The fuel temperature rise is suppressed, and the fuel temperature fluctuates to the temperature displacement side indicated by Lm in FIG.
As a result, even when traveling in a high-temperature region, the fuel temperature at the inlet of the high-pressure fuel pump 30 exceeds the required fuel temperature Tk of the high-pressure fuel pump, for example, 80 ° C. The control target of preventing can be achieved and the engine output can be prevented from lowering.

Next, a fuel supply device M2 for an internal combustion engine as a second embodiment of the present invention will be described.
In contrast to the first embodiment, the second embodiment has the same components except that the flow path switching means 11a is a three-way switching valve 12 provided in the merging section 8 and that this control section is added. In many cases, the same members are denoted by the same reference numerals, and redundant description is omitted.
As shown in FIG. 4, the flow path switching means 11a provided at the junction 8 here is arranged in the storage box 24a. The accommodation box 24 a is provided with a normally open air inlet 25 on the side wall thereof, and a fuel cooler 6 image is arranged on the inner side of the air inlet 25.
The three-way switching valve 12 disposed in the junction 8 has a first inflow port p1 that communicates with the fuel cooler 6, a second inflow port p2 that communicates with the bypass line 9, and an outflow port p3 that reaches the fuel tank 2 downstream. It communicates with the return line 501.

  Here, a temperature sensor 13 is provided in the vicinity of the outflow port p3 of the merging portion 8 so as to pass through the merging portion 8, that is, the fuel whose temperature drop is suppressed by the bypass pipe 9, or cooled by the fuel cooler 6. Each temperature of the detected fuel is detected and output to the control means 14.

  The three-way switching valve 12 here is an electromagnetic switching valve, and the first inflow port p1 communicates with the outflow port p3 in a fuel temperature state (Lh state) that receives an output exceeding a high temperature predetermined temperature (high temperature side first temperature Tf2). In the fuel temperature state in which the fuel in the fuel cooler 6 can flow to the fuel tank 2 and receives an output lower than the low temperature predetermined temperature (low temperature side first temperature Tf1), the second inflow port p2 communicates with the outflow port p3 to bypass The fuel in the conduit 9 can flow to the fuel tank 2.

The control means 14 is composed of a digital computer, and includes a ROM 142, a RAM 143, a CPU 144, an input port 145, and an output port 146 connected to each other via a bidirectional bus 141, and exhibits a switching control function described later. Here, the engine speed Ne, the intake air amount Qa, and the water temperature Tw, which are vehicle operation information, are input to the input port 145 from sensors (not shown), and further, the fuel pressure Pf from the fuel pressure sensor 21 and the temperature sensor 13 The fuel temperature Tfn in the vicinity of the outflow port p3 of the junction 8 is input.
The operation of the fuel supply device M2 for the internal combustion engine according to the second embodiment will be described with reference to the temperature fluctuation characteristic diagram of FIG. 3 and the flowchart of the fuel supply control routine of FIG.

The control means 14 performs drive control of the engine 1 in accordance with vehicle operation information in a main routine (not shown) when the vehicle is running, and in particular, controls the fuel injection device 3 and the fuel supply device M2 sequentially at respective control timings. Do. Here, in the fuel injection control, the common rail pressure, the injection amount, and the injection timing are calculated according to the operation information, and the high-pressure fuel pump 15 and the fuel injection valve 17 of each cylinder are driven according to the calculation result to generate a desired output. It is controlled as follows.
On the other hand, fuel supply control is performed according to the fuel supply control routine of FIG.
Here, when step s1 is reached, the fuel temperature of the latest junction 8 (shown schematically as the same position as the fuel cooler outlet in FIG. 3) is set as a return fuel temperature Tfn, which is an excess fuel temperature, by the temperature sensor 13. Detect and store.

In step s2, it is determined whether the vehicle is traveling in a normal temperature range, for example, a region where the first low temperature side temperature set in advance is a low temperature determination value Tf1 (20 ° C.) or higher, or a low temperature region lower than that. If it is determined that the vehicle is traveling in the normal temperature range, the process proceeds to step s3. If it is determined that the vehicle is traveling in the low temperature range, the process proceeds to step s4.
When step s4 is reached, an ON output is issued to the three-way switching valve 12, the fuel cooler 6 and the fuel tank 2 are shut off, and the bypass passage 9 and the fuel tank 2 are communicated.

  When traveling in the cold region is continued, the return fuel temperature Tfn is inherently excessively cooled by the outside air because of traveling in the cold region, and fluctuates to a low temperature side lower than the low temperature side second temperature (supercooling temperature) Tc. For example, as indicated by a two-point difference line indicated by a symbol Lb1 in FIG. 3, the fuel temperature is lowered and fluctuates from the symbol c1, and is pressurized and heated by the injection pump 15 to rise in temperature, but the injection pump 15 and the fuel injection valve 17 When the fuel is discharged from the common rail 16 as surplus fuel, it is cooled again by outside air. In particular, when the fuel passes through the fuel cooler 6 in this state, the fuel is excessively cooled, falls below the supercooling temperature Tc and flows into the fuel tank 2, and in this case, precipitates such as wax are generated due to the supercooling. In some cases, deposits in the fuel in the tank cannot be melted. When the fuel mixed with the wax is discharged again from the low-pressure fuel pump 18 and flows through the fuel supply path R1, the clogging of the pump 18 itself, the low-pressure fuel pump side filter 181 and the filter 30 proceeds, and the flow path resistance increases. However, there is a problem in securing a predetermined fuel supply amount.

However, in order to prevent the occurrence of such a situation, in the fuel supply control device M2, in step s4, the three-way switching valve 12 is turned on to switch the fuel to the bypass path 9 and return to the fuel tank 2. I have control.
For this reason, excessively low temperature is prevented by passing through the bypass 9, and the fuel whose temperature fluctuated originally along the symbol Lb <b> 1 (the state where the temperature c <b> 1 at the fuel tank inlet is lower than Tc) shown in FIG. 3 is The fuel cooler 6 can be held without being affected, and is displaced along the thin two-dot chain line La1 shown in FIG. 3 so that the temperature at the position reaching the fuel tank 2 inlet holds c2 and is lower than the supercooling temperature Tc. To be prevented.

Further, the fuel in this state rises in temperature along the two-dot chain line Lb2 and circulates, so that the temperature at the position where it reaches the inlet of the fuel tank 2 again maintains c3 and further exceeds the supercooling temperature Tc. Become. Eventually, the state of fluctuation L1 indicated by a solid line in FIG. 3 is reached, and a balance is maintained between heat radiation to the outside air and heating from the engine 1 side. In such a traveling state, even in a cold region, the fuel temperature is kept sufficiently higher than the supercooling temperature Tc, and precipitates such as wax are prevented from being generated in the fuel flowing into the fuel tank 2.
Furthermore, even if deposits such as wax are generated in the fuel tank 2, the wax can be melted in the tank by the rise in the temperature of the fuel flowing into the fuel tank 2. For this reason, even if the fuel in the tank again flows into the supply line 4, clogging of the filters 181 and 30 and malfunction of the low-pressure fuel pump 18 can be prevented, and an insufficient fuel supply of the engine occurs. It can be surely prevented.

Further, when proceeding to steps s5 and s6, here, the latest return fuel temperature Tfn which is the temperature of the surplus fuel from the fuel injection device 3 is read, and it is determined whether this is below the supercooling temperature Tc. If the fuel exceeds the supercooling temperature Tc, the control of this cycle is returned. If the outside air temperature is relatively low, the process proceeds to step s8.
When step s8 is reached by traveling in the low temperature range, it is determined whether or not the return fuel temperature Tfn of the traveling fuel is a low temperature equal to or lower than the low temperature side second temperature (supercooling temperature) Tc for determining the supercooling state.
The temperature at which the fuel in the fuel tank 2 generates precipitates such as wax due to supercooling is set based on, for example, −2 ° C., where the low temperature judgment value Tf1 melts the precipitates such as wax in the fuel tank. In order to correct the fuel temperature and the variation, it is preset as 20 ° C. with a correction value.

If Yes in step s8, if the temperature of the fuel does not increase, the process proceeds to step s9 because the temperature is lowered. In step s9, the surplus fuel increase command signal S1 for increasing and correcting the return fuel, which is surplus fuel, is output to the main routine (not shown) of the control means 14, and the process returns to the main routine.
In step s8, if the temperature is higher than the supercooling temperature Tc, the process proceeds to the No side, the control of this time is terminated, and the process returns to the main routine.

  On the main routine side that has received the surplus fuel increase command signal S1 in step s9 from the fuel supply control routine, the discharge amount of the high-pressure fuel pump 15 is increased by a predetermined amount. Due to this increase correction control, the amount of heated surplus fuel that is returned from the common rail 16 to the fuel tank 2 via the return line 5 increases, and the fuel temperature in the fuel tank 2 rises. From the temperature displacement indicated by the symbol Lb1 in FIG. It is possible to accelerate the temperature displacement approaching the temperature rising side indicated by the symbol L1. As a result, the fuel at a relatively high temperature gradually increases, and precipitates such as wax previously flowing into the fuel tank 2 can be melted, and the filters 181 and 30 are clogged and the low-pressure fuel pump Therefore, it is possible to reliably prevent the engine from being insufficiently supplied with fuel.

On the other hand, when the fuel temperature Tfn reaches the low temperature determination value Tf1 (20 ° C.) or higher in step s2 and reaches step s3, it is determined whether or not the fuel temperature Tfn is equal to or higher than the predetermined high temperature determination value Tf2 (60 ° C.). In the following, the current state is maintained, this control is terminated, and the process returns to the main routine.
Note that the high temperature predetermined temperature (high temperature side first temperature Tf2: 60 ° C.) is controlled by reliably performing control to prevent the high pressure fuel pump side required fuel temperature Tk, for example, 80 ° C. from being exceeded. The predetermined high temperature (high temperature side first temperature Tf260 ° C.) is appropriately set with a margin, but instead, another temperature equal to or lower than the required fuel temperature Tk may be set.

In this way, when the fuel temperature Tfn is in the normal fuel temperature region not lower than the low temperature determination value Tf1 (20 ° C.) and not higher than the high temperature determination value Tf2 (60 ° C.), for example, it is in the steady normal temperature traveling region indicated by the symbol Ln in FIG. Here, since the outside air temperature is not excessively high, the fuel cooler 6 is cooled, and the temperature in the fuel tank 2 maintains the fluctuation state of the symbol Ln shown by the solid line, that is, the heat radiation action to the outside air and the engine 1. A balance with the heating action from the side is maintained.
On the other hand, when the fuel temperature at the junction 8 exceeds the high temperature judgment value Tf2, the routine reaches step s10, and a switching fuel temperature output is issued to the three-way switching valve 12, the bypass passage 9 and the fuel tank 2 are shut off, and the fuel cooler 6 The fuel tank 2 is connected.

In this case, for example, the fuel temperature particularly tends to be raised by heating on the engine side, pressurization of the injection pump, or heating action due to the high temperature traveling region indicated by the symbol Lh in FIG. As a result, the temperature of each member of the fuel supply system rises and, for example, the fuel temperature Tfn exceeds 60 ° C. on the fuel tank 2 side.
When reaching step s11, s12 from step s10 in such a high temperature traveling region, here, the latest return fuel temperature Tfn is read again, and it is determined whether this exceeds the high temperature determination value Tf2 (60 ° C.), If it is lower than this, the control in this control cycle is returned, the outside air temperature is relatively high, and the temperature of the fuel tends to further increase. When the high-pressure fuel pump side required fuel temperature Tk is reached, the process proceeds to step s13.

In step s13, the surplus fuel reduction command signal S2 for correcting the reduction of the return fuel as surplus fuel is output to the main routine (not shown) of the control means 14, and in step s14, the latest return fuel temperature Tfn is high. It is determined whether or not the fuel pump side required fuel temperature Tk (80 ° C.) is exceeded. In the following, the control of this association is terminated, and if it exceeds, the process proceeds to step s15.
When step s15 is reached, an output control command signal S3 for restricting the generation of a high output exceeding a certain value of the engine is output to the main routine (not shown), this control is terminated, and the process returns to the main routine.

  In step s13 of the fuel supply control routine, on the main routine side that has received the surplus fuel reduction command signal S2, the discharge amount of the high-pressure fuel pump 15 is reduced by a predetermined amount, whereby the fuel tank passes through the return line 5 from the common rail 16 side. The heated surplus fuel returned to 2 is reduced, the temperature rise of the fuel temperature in the fuel tank 2 is suppressed, and the temperature is changed from the temperature displacement indicated by Lh in FIG. 3 to the temperature displacement side indicated by Lm on the low temperature side.

  Further, in step s15 of the fuel supply control routine, the main routine that receives the output control command signal S3 enters control for restricting the generation of a high output exceeding a predetermined value of the engine, thereby suppressing the high output of the engine. The low temperature displacement surely progresses and eventually reaches the temperature displacement side indicated by the symbol Lm in FIG. 3, and the balance between the heat radiation action to the outside air and the heating action on the engine 1 side is maintained. A cooling action is also added, and the temperature in the fuel tank 2 is maintained in the fluctuation state of the symbol Lm shown by the solid line. In this case, the high-pressure fuel pump side required fuel temperature Tk, for example, 80 ° C. accompanying excessively high temperature is not exceeded, and a decrease in engine output can be prevented.

As described above, the air inlet 25 provided on the side walls of the storage boxes 24 and 24a is normally open. However, in some cases, the third embodiment using the storage box 24b provided with the fuel cooler shutter 33 for opening and closing the air inlet 25 is used. A form may be configured. In this case, the cooling function of the fuel cooler 6 and the heat retaining function of the bypass pipe 9 can be enhanced.
This third embodiment is different from the second embodiment in that a fuel cooler shutter 33 and a radiator shutter 37 are provided, and these controls are added. Otherwise, for example, the flow path switching of the third embodiment is performed. The means adopts the same configuration as the flow path switching means 11a used in the second embodiment. Here, the same members are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 6, the storage box 24 b fastened to the floor plate 23 at the lower part of the vehicle body accommodates and supports the fuel cooler 6 and the bypass pipe 9 therein, and the air inlet 25 is provided on the side wall approaching the fuel cooler 6. It is formed. The air inlet 25 is formed to be openable and closable by a fuel cooler shutter 33.
The fuel cooler shutter 33 includes a rectangular frame member 331, a shutter plate 34 that is supported by the rectangular frame member 331 and arranged in parallel in the vertical direction, a link member 35 that opens and closes each shutter plate 34 about its rotation axis, and a link member And a motor 36 that opens and closes a plurality of shutter plates 34 arranged in parallel via 35, and the opening and closing drive control of the motor 36 is performed by the control means 14.

On the other hand, a radiator 40 for cooling the engine by guiding the cooling air to the radiator 40 side by driving the fan 42 is disposed at the front of the engine 1. A radiator shutter 37 that allows and blocks the flow of cooling air toward the radiator 40 is disposed at the front of the radiator 40.
The radiator shutter 37 includes a rectangular frame member 371, a shutter plate 38 that is supported by the rectangular frame member 371 and arranged in parallel in the vertical direction, a link member 39 that opens and closes each shutter plate 38 around its rotation axis, and a link member 39. And a motor 41 that opens and closes a plurality of shutter plates 38 arranged in parallel, and the opening and closing drive control of the motor 41 is performed by the control means 14.

The operation of the fuel supply device M3 for the internal combustion engine of the third embodiment will be described using the flowchart of the fuel supply control routine of FIG.
Here, each control step of the fuel supply control routine of FIG. 7 has many identical step configurations as compared with the fuel supply control routine of FIG.
In the fuel supply control routine of FIG. 7, the latest return fuel temperature Tfn of the junction 8 is detected in steps a1 and a2, and if this is equal to or higher than the low temperature determination value Tf1 (20 ° C.), the process proceeds to step a3 and travels in the low temperature range. If it judges, it will progress to step a4.
When step a4 is reached, an ON output is issued to the three-way switching valve 12 in cold districts to connect the bypass passage 9 and the fuel tank 2, and then the routine proceeds to step a5 where the return fuel temperature Tfn is detected.

Next, at step a6, it is determined again whether or not the return fuel temperature Tfn is equal to or higher than the low temperature determination value Tf1 (20 ° C.). If the return fuel temperature Tfn is higher than the low temperature determination value Tf1, the control at this time is terminated. If it falls below, the process proceeds to step a7. Here, it is a case where the temperature rise of the fuel does not advance, and the surplus fuel increase command signal S1 for correcting the increase of the return fuel is output.
On the main routine side that has received the surplus fuel increase command signal S1 in step a7, the discharge amount of the high-pressure fuel pump 15 is corrected by a predetermined amount, the heated surplus fuel is increased, and the temperature of the fuel tank 2 is increased. For example, the temperature is closer to the temperature rising side indicated by the symbol L1 than the temperature displacement indicated by the symbol Lb1 in FIG. Further, precipitates such as wax in the fuel in the fuel tank 2 can be melted, clogging of the filters 181 and 30 and malfunction of the low-pressure fuel pump 18 can be prevented, resulting in insufficient fuel supply to the engine. Can be surely prevented.

Next, the process proceeds to step a8, where the latest return fuel temperature Tfn of the junction 8 is detected. Then, when the process reaches step a9 and step a10, the latest return fuel temperature Tfn becomes the low temperature side second temperature (supercooling temperature) Tc. It is determined whether or not the temperature is the following, and if the temperature is higher than the supercooling temperature Tc, the control of this time is finished. On the other hand, when the temperature is kept low in the cold region, a shutter closing output is issued to the motor 41 of the radiator shutter 37 and a shutter closing output is issued to the motor 36 of the fuel cooler shutter 33.
As a result, the shutter plates 38 are closed to block the cooling air from the radiator 37 to increase the water temperature of the engine 1, thereby increasing the temperature of the fuel approaching the engine body. Further, each shutter plate 34 of the air guide port 25 of the storage box 24b is closed to block the flow of the traveling wind to the fuel cooler 6 and the bypass pipe 9 therein, and the fuel flowing from the bypass pipe 9 to the fuel tank 2 is blocked. Prevent cooling and keep warm.

On the other hand, when step a3 is reached from step a2 described above, here, if the fuel temperature Tfn is equal to or lower than a predetermined high temperature determination value Tf2 (60 ° C.), the current control is terminated to maintain the current state, and the main routine Return to
On the other hand, when the fuel temperature at the junction 8 exceeds the high temperature determination value Tf2 and reaches step a11, a switching fuel temperature output is issued to the three-way switching valve 12 so that the fuel cooler 6 and the fuel tank 2 communicate with each other. If it is a high-temperature traveling region indicated by reference numeral Lh, cooling by the fuel cooler 6 is attempted. Further, when the steps a12 and a13 are reached in such a high temperature traveling region, it is determined whether or not the latest return fuel temperature Tfn exceeds the high temperature judgment value Tf2 (60 ° C.). If the fuel temperature rises further, the process proceeds to step a14.

When the process proceeds to step a14, here, the cooling of the fuel does not proceed, and the surplus fuel reduction command signal S2 is output in order to correct the return fuel to be reduced.
On the main routine side that has received the surplus fuel reduction command signal S2, the discharge amount of the high-pressure fuel pump 15 is reduced by a predetermined amount, whereby the heated surplus fuel is reduced, and the increase in the fuel temperature of the fuel tank 2 is suppressed. The
In step a14, the surplus fuel reduction command signal S2 is output and the generation of a high output of the engine is suppressed, and as the temperature decreases, the temperature displacement eventually reaches the temperature displacement side indicated by the symbol Lm in FIG. .

As a result, even when traveling in a high-temperature region, the cooling action of the fuel cooler 6 is also added, and the temperature in the fuel tank 2 is maintained in the fluctuation state of the symbol Lm indicated by the solid line. In this case, the high-pressure fuel pump side required fuel temperature Tk, for example, 80 ° C. accompanying excessively high temperature is not exceeded, and a decrease in engine output can be prevented.
Next, the process proceeds to steps a15 and a16. Here, the latest return fuel temperature Tfn is taken, and it is determined whether or not it exceeds the required fuel temperature Tk (80 ° C) on the high-pressure fuel pump side due to excessive temperature rise, and if it is lower, control of this control cycle is returned. If the fuel temperature tends to further increase, the process proceeds to steps a17 and a18.

In step a17, the temperature of the fuel tends to increase. Here, each open state of the radiator shutter 37 and the fuel cooler shutter 33 is detected by a limit switch (not shown). In the open state, the process proceeds to step a19, and in the closed state. Proceed to step a18. Here, a shutter opening output is issued to the motor 41 of the radiator shutter 37, and a shutter opening output is issued to the motor 36 of the fuel cooler shutter 33.
As a result, the shutter plates 38 are opened and the cooling air is passed through the radiator 37 to cool the engine 1, thereby preventing the temperature of the fuel approaching the engine body from rising. Furthermore, each shutter plate 34 of the air guide port 25 of the storage box 24b is opened to introduce the traveling air to the fuel cooler 6 inside the shutter plate 34 to promote the cooling of the fuel toward the fuel tank 2.

Next, when proceeding to step a19, it is determined whether or not the latest return fuel temperature Tfn is higher than the high-pressure fuel pump side required fuel temperature Tk. When not progressing, it progresses to step a20.
When step a20 is reached, an output control command signal S3 for restricting the generation of a high output exceeding a certain value of the engine is output to the main routine (not shown), this control is terminated, and the process returns to the main routine.

  As described above, in step a14 of the fuel supply control routine, on the main routine side that has received the surplus fuel reduction command signal S2, the discharge amount of the high-pressure fuel pump 15 is reduced by a predetermined amount, and thereby the return line from the common rail 16 side. The amount of the heated surplus fuel that is returned to the fuel tank 2 through 5 is reduced, the temperature rise of the fuel temperature in the fuel tank 2 is suppressed, and the temperature displacement side indicated by reference numeral Lm on the lower temperature side than the temperature displacement indicated by reference numeral Lh in FIG. Fluctuates.

Furthermore, in step a20 of the fuel supply control routine, on the main routine side that has received the output control command signal S3, the control for restricting the generation of high output exceeding a certain value of the engine is entered, so that the high output generation of the engine is suppressed, The low temperature displacement surely progresses and eventually reaches the temperature displacement side indicated by the symbol Lm in FIG. 3, and the balance between the heat radiation action to the outside air and the heating action on the engine 1 side is maintained. A cooling action is also added, and the temperature in the fuel tank 2 is maintained in the fluctuation state of the symbol Lm shown by the solid line. In this case, the high-pressure fuel pump side required fuel temperature Tk (80 ° C.) due to excessive temperature rise is not exceeded, and engine output reduction can be prevented.
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1 Engine 2 Fuel tank 3 Fuel injection apparatus 4 Supply line 5 Return line 6 Fuel cooler 7 Branch part 8 Merge part 9 Bypass path 11 Flow path switching means 12 Three-way switching valve 13 Temperature sensor 14 Control means 45 Thermostat Tf1 Low temperature judgment value Tf2 High temperature judgment value Tfn Fuel temperature Tk High pressure fuel pump side required fuel temperature (high temperature side second temperature)
Tc Supercooling temperature (second temperature on the low temperature side)
M1, M2, M3 Fuel supply device for internal combustion engine

Claims (5)

A supply line for supplying fuel from the fuel tank to the fuel injection device of the engine, a return line for cooling surplus fuel from the fuel injection device to the fuel tank by cooling with a fuel cooler, and a flow through the return line A bypass path for flowing the fuel to bypass the fuel cooler to the downstream junction from the upstream branch of the fuel cooler, and the return pipe or the bypass depending on the temperature of the fuel passing through the junction Comprising flow path switching means for communicating either one of the paths and the fuel tank;
The flow path switching unit causes the fuel cooler and the fuel tank to communicate with each other when the temperature of the fuel passing through the junction is higher than the first temperature on the high temperature side, and the fuel temperature is a low temperature lower than the first temperature on the low temperature side. And a thermostat that switches the bypass path and the fuel tank to communicate with each other,
Comprising surplus fuel control means for controlling the surplus fuel amount from the fuel injection device;
The fuel supply device for an internal combustion engine, wherein the surplus fuel control means increases the surplus fuel amount when the fuel temperature falls below a low temperature side second temperature lower than the low temperature side first temperature . 2. The fuel supply device for an internal combustion engine according to claim 1 , wherein the bypass passage is held in a storage box supported at a lower portion of a vehicle body . The fuel supply device for an internal combustion engine according to claim 2 , wherein the bypass path is held in a storage box supported at a lower part of a vehicle body together with the fuel cooler . The storage box includes a shutter that guides outside air to the fuel cooler, and the control means switches the shutter to an open state when the fuel temperature exceeds the first temperature on the high temperature side, and closes when the temperature falls below the second temperature on the low temperature side. 4. The fuel supply device for an internal combustion engine according to claim 3 , wherein the fuel supply device is switched to a state . Comprising output control means for controlling the output generated by the internal combustion engine;
2. The output control means limits the generation of a high output exceeding a predetermined value from the internal combustion engine in the previous period when the fuel temperature exceeds a high temperature side second temperature higher than the high temperature side first temperature. the fuel supply apparatus for an internal combustion engine according to any one of to 4.

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