JP2006125249A - Cooling control device of gas fuel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling control device of a gas fuel engine which allows cooling of a desired cooled part. <P>SOLUTION: A cooling control device is equipped with at least a temperature sensor 6a for estimating temperature of an NSR catalyst 8 of a cooled part, a passage 82 for cooled part cooling which is arranged in the NSR catalyst 8, a cooling fuel line 3L which is branched from a low-pressure gas fuel line 32 connected to a delivery pipe 4, communicating with the delivery pipe 4 through the medium of the passage 82 for cooled part cooling and provided with check valves 3c, 3e for preventing back-flow, and a cutoff valve 3d for changing a flow rate distribution from the low pressure gas fuel line 32 to the cooling fuel line 3L. When the temperature obtained by the temperature sensor 6a exceeds the prescribed value, the cutoff valve 3d allows circulation of low-pressure gas fuel from the low-pressure gas fuel line 32 to the cooling fuel line 3L. When the obtained temperature is lower than the prescribed value, the cutoff valve 3d restricts the circulation of the low-pressure gas fuel to the cooling fuel line 3L. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling control device for a gas fuel engine including a low-pressure gas fuel line that decompresses high-pressure gas fuel in a fuel tank with a regulator and supplies the fuel gas to each injector via a delivery pipe.

Conventionally, from the viewpoint of environmental protection and the like, it has been required to reduce harmful gas components in exhaust gas from an internal combustion engine, for example, NOx, and in order to enable this, when the air-fuel ratio of the exhaust gas is lean the occluding NO _X in the exhaust gas, NOx occlusion-reduction catalyst for reducing NO _X which is occluded when the air-fuel ratio of the exhaust gas is lowered with respect thereto (hereinafter, referred to NSR catalyst.) in the exhaust passage Arrangement has been made. On the other hand, a so-called gas fuel engine that uses compressed natural gas (hereinafter referred to as CNG) or hydrogen gas as a fuel has been developed as an energy measure and an environmental measure. For example, a technique described in Patent Document 1 is disclosed in order to reduce NOx in exhaust gas by being disposed in the exhaust passage.

  The gas fuel internal combustion engine disclosed in Patent Document 1 is a gas fuel internal combustion engine in which the air-fuel ratio of an air-fuel mixture combusted in a combustion chamber is maintained at a lean air-fuel ratio. In order to temporarily switch the air-fuel ratio of the exhaust gas discharged from the combustion chamber to a target air-fuel ratio that is set richer than the lean air-fuel ratio, an injection valve is provided from the gas fuel injection valve in the combustion stroke or the exhaust stroke. Gas fuel is injected secondarily.

JP 2004-076686 A

  By the way, generally, the temperature of the NSR catalyst provided in the exhaust passage rises due to high-temperature exhaust gas, NOx occlusion reduction reaction, and the like. However, when the NSR catalyst reaches a high temperature of, for example, 550 ° C. or higher, the NOx purification rate decreases. Therefore, the gas-fuel internal combustion engine described in Patent Document 1 sometimes fails to perform lean combustion, and as a result, fuel efficiency is improved by lean combustion. There is a problem that it cannot be planned.

  On the other hand, since gas fuel is a gas, considering the charging efficiency of the intake air into the combustion chamber, it is desirable that it be directly injected into the combustion chamber during the compression stroke, and the output can be improved by increasing the intake air charging efficiency. It is. However, in comparison with gasoline, intake air charging efficiency is small because there is no decrease in intake air temperature due to latent heat of vaporization. Therefore, it is necessary to cool the intake air, but this is not possible with the gas fuel internal combustion engine described in Patent Document 1.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cooling control device for a gas fuel engine that solves the above-described problems and enables a desired cooled portion to be cooled, for example, to lower the temperature of the NSR catalyst and the intake air temperature.

  A cooling control device for a gas fuel engine according to a first embodiment of the present invention that achieves the above object is a low-pressure gas fuel line that depressurizes high-pressure gas fuel in a fuel tank by a regulator and supplies it to each injector via a delivery pipe. A cooling control device for a gas fuel engine comprising: a cooled part temperature acquisition means for detecting or estimating a temperature of a cooled part; a cooled part cooling passage disposed in the cooled part; and a downstream of the regulator A cooling fuel line that branches off from the low-pressure gas fuel line, communicates with the delivery pipe or a low-pressure gas fuel line upstream thereof via a passage for cooling the cooled portion, and has a check valve that prevents backflow; and low-pressure gas fuel The temperature acquired by the changing means for changing the flow rate distribution from the line to the cooling fuel line and the temperature to be cooled part acquiring means exceeds a predetermined value. The change means allows the flow from the low-pressure gas fuel line to the cooling fuel line, and when the acquired temperature is lower than the predetermined value, the change means controls to restrict the flow to the cooling fuel line. And a control means.

  In addition, the cooling control device for a gas fuel engine according to the second aspect of the present invention that achieves the above object is a low-pressure gas that depressurizes high-pressure gas fuel in a fuel tank by a regulator and supplies the injector to each injector via a delivery pipe. A cooling control device for a gas fuel engine including a fuel line, a cooled portion temperature acquisition means for detecting or estimating a temperature of a cooled portion, a cooled portion cooling passage disposed in the cooled portion, and a regulator Refrigerant is circulated through the heat exchanger arranged around the low-pressure gas fuel line downstream, the cooled part cooling passage and the heat exchanger, the refrigerant line where the circulation pump is arranged, and the cooled part temperature acquisition When the temperature acquired by the means exceeds a predetermined value, the circulation pump is operated, and when the acquired temperature is less than the predetermined value, the operation of the circulation pump is stopped. Characterized in that it comprises control means for the.

  Furthermore, the cooling control apparatus for a gas fuel engine according to the third aspect of the present invention that achieves the above object is a low-pressure gas that decompresses the high-pressure gas fuel in the fuel tank with a regulator and supplies it to each injector via a delivery pipe. A cooling control apparatus for a gas fuel engine including a fuel line, comprising: a cooled part temperature acquisition means for detecting or estimating a temperature of a cooled part; a cooled part cooling passage disposed in the cooled part; When the refrigerant is circulated through the cooling part cooling passage and the refrigerant passage arranged in the regulator, and the temperature obtained by the refrigerant line in which the circulation pump is arranged and the part to be cooled temperature acquisition means exceeds a predetermined value Comprises a control means for operating the circulation pump and controlling the operation of the circulation pump to be stopped when the acquired temperature is lower than a predetermined value. To.

  Here, the part to be cooled is preferably a NOx occlusion reduction type catalyst provided in the exhaust passage.

  Moreover, it is preferable that a site to be cooled is an intake passage.

  Furthermore, it is desirable that the control of the changing means by the control means when the part to be cooled is a NOx occlusion reduction type catalyst is executed only during lean combustion.

  Further, it is preferable that the control of the circulation pump by the control means when the site to be cooled is a NOx occlusion reduction type catalyst is executed only during lean combustion.

  According to the first aspect of the present invention, when the high-pressure gas fuel is depressurized by the regulator, the low-pressure gas fuel flowing downstream of the regulator is set to a low temperature, and when the temperature of the cooled portion exceeds a predetermined value, the low-pressure gas fuel It is possible to cool the cooled portion by flowing the fuel through the cooled portion cooling passage.

  Further, according to the second aspect of the present invention, when the high-pressure gas fuel is depressurized by the regulator, the low-pressure gas fuel flowing downstream of the regulator is lowered to a low temperature, and when the temperature of the cooled portion exceeds a predetermined value, It is possible to cool the cooled portion by circulating the refrigerant cooled by the low pressure gas fuel through the heat exchanger to the cooled portion cooling passage.

  Further, according to the third aspect of the present invention, the high-pressure gas fuel is decompressed by the regulator, and the low-pressure gas fuel that flows downstream of the regulator and the regulator that is a peripheral part through which the low-pressure gas fuel flows are cooled to a low temperature. When the temperature of the part exceeds a predetermined value, the cooled part can be cooled by circulating the low-pressure gas fuel or the refrigerant cooled by the regulator itself through the cooling part cooling passage.

  Here, according to the embodiment in which the portion to be cooled is the NSR catalyst provided in the exhaust passage, it is possible to cool the NSR catalyst to a temperature range where the NOx occlusion efficiency is high.

  Further, according to the form in which the part to be cooled is the intake passage, the intake passage is cooled by cooling the intake passage, and the intake charge efficiency into the combustion chamber can be increased.

  Furthermore, according to the embodiment in which the control of the changing means by the control means when the site to be cooled is the NOx occlusion reduction type catalyst is executed only during lean combustion, it becomes possible to store NOx accurately during lean combustion.

  Furthermore, according to the embodiment in which the control of the circulation pump by the control means when the cooled portion is a NOx storage reduction catalyst is executed only during lean combustion, it becomes possible to store NOx accurately during lean combustion. .

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  First, a first embodiment of a cooling control apparatus for a gas fuel engine according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram for explaining a cooling control apparatus 101 for a gas fuel engine according to the first embodiment, and FIG. 2 is a flowchart for controlling the cooling control apparatus 101 for the gas fuel engine in FIG. It is an example.

  The intake port of the engine 1 is connected to the intake manifold 2. On the other hand, the exhaust port of the engine 1 is connected to an exhaust manifold 5 and an exhaust pipe 6, and a three-way catalyst 7 and an NSR catalyst 8 are arranged in the exhaust pipe 6. Specifically, it is connected to the three-way catalyst 7 via the first exhaust pipe 61 and is connected to the NSR catalyst 8 via the second exhaust pipe 62, and the NSR catalyst 8 is further communicated with the third exhaust pipe 63. .

  The engine 1 shown in FIG. 1 includes a gas fuel supply system 3 that uses CNG as gas fuel. A delivery pipe 4 communicates with a CNG direct injection injector 41 as a direct injection injector. The delivery pipe 4 includes a gas fuel container mounted on the vehicle via a regulator 3a that decompresses the high pressure gas fuel in the low pressure gas fuel line 32 and the fuel tank 31 into the low pressure gas fuel in the gas fuel supply system 3. A fuel tank 31 is connected. A temperature sensor 3b for measuring the temperature of the low-pressure gas fuel is disposed in the low-pressure gas fuel line 32 downstream of the regulator 3a. In the engine 1, the piston cavity 12 adapted to the injection direction from the CNG direct injection injector 41 is formed offset to the intake port side. The gas fuel in the fuel tank 31 is referred to as high pressure gas fuel, and the gas fuel decompressed by the regulator 3a is referred to as low pressure gas fuel.

  Further, the gas fuel supply system 3 is branched from the low-pressure gas fuel supply line 32 at a branch point J downstream of the regulator 3a, more specifically downstream of the temperature sensor 3b, and then further joined to the low-pressure gas fuel supply line 32. Line 3L is provided. The cooling fuel line 3L includes a first cooling fuel line 33 and a second cooling fuel line 34 that are communicated with each other via a cooled portion cooling passage 82 described later. The first cooling fuel line 33 is provided with a check valve 3c that branches off from the low-pressure gas fuel line 32 and immediately prevents the backflow of the low-pressure gas fuel, and downstream from the low-pressure gas fuel line 32 to the cooling fuel line 3L. That is, a shut-off valve 3d as a changing means for changing the flow rate distribution of the low-pressure gas fuel to the first cooling fuel line 33 is arranged. The second cooling fuel line 34 is provided with a check valve 3e for preventing the back flow of the low pressure gas fuel near the junction C with the low pressure gas fuel line 32. The shut-off valve 3d is configured to change between a case where low-pressure gas fuel is supplied to the delivery pipe 4 via only the low-pressure gas fuel line 32 and a case where low-pressure gas fuel is supplied to the delivery pipe 4 also via the cooling fuel line 3L. The electromagnetic valve is controlled by the ECU 300. In the first embodiment, the cooling fuel line 3L is branched from the low-pressure gas fuel line 32 downstream of the regulator 3a, and communicates with the low-pressure gas fuel line 32 upstream of the delivery pipe 4 via the cooled portion cooling passage 82. However, it may be communicated with the delivery pipe 4 itself.

  The high-pressure gas fuel filled in the fuel tank 31 with a filling pressure (for example, 20 MPa) is decompressed to a certain high regulation pressure (for example, 5 MPa) by the regulator 3a, and the CNG direct injection injector with this high regulation pressure. 41 is injected into the combustion chamber 11 by, for example, a compression stroke. This high regulation pressure is a pressure at which in-cylinder injection is always possible in the compression stroke regardless of the operating state. The CNG direct injection injector 41 is controlled based on an output signal from the ECU 300 described later.

  The low-pressure gas fuel that is decompressed by the regulator 3a and flows to the low-pressure gas fuel supply line 32 and the cooling fuel line 3L is at a lower temperature than the high-pressure gas fuel. This is because the pressure reduction by the regulator 3a is performed in a state close to adiabatic expansion. As a result, the temperature of the low-pressure gas fuel and the regulator 3a, which is a peripheral part through which the low-pressure gas fuel flows, are lowered. In the first embodiment, by utilizing this phenomenon, specifically, the low-temperature gas fuel having a low temperature is used as a refrigerant, so that the NSR catalyst 8 that is a cooled portion can be cooled as described later. .

  On the other hand, as described above, the three-way catalyst 7 disposed in the exhaust pipe 6 is provided to purify mainly harmful three components HC, CO, and NOx from the exhaust gas. The NSR catalyst 8 disposed in the exhaust pipe 6 is also provided for purifying NOx contained in the exhaust gas by the three-way catalyst 7, so that when there is a large amount of NOx such as during lean combustion. When NOx is occluded and the air-fuel ratio of the exhaust gas is made rich, the occluded NOx is reduced. As shown in FIG. 1, the NSR catalyst 8 has a double structure, and the NSR catalyst 8 contains a catalyst, which should be the NSR catalyst itself, and a catalyst containing flow path 81 which is a flow path through which exhaust gas flows. And a cooled portion cooling passage 82 disposed around the catalyst containing flow path 81. The low-pressure gas fuel is allowed to flow through the cooled portion cooling passage 82 so that the NSR catalyst 8 that is the cooled portion can be cooled. In order to estimate the temperature of the NSR catalyst 8, a temperature sensor 6 a that is a temperature acquisition unit is provided in the exhaust pipe 62 that is upstream of the NSR catalyst 8. In order to estimate or detect the temperature of the NSR catalyst 8, a temperature sensor may be provided in each of the exhaust passages upstream and downstream of the NSR catalyst 8, or a temperature sensor is provided only in the exhaust passage on the downstream side of the NSR catalyst 8. Alternatively, the NSR catalyst 8 may be directly provided with a temperature sensor. Of course, the temperature sensor is not limited to a temperature sensor.

  The cooling control apparatus 101 for a gas fuel engine according to the present invention includes an electronic control unit (ECU) 300 that performs basic control such as control of the CNG direct injection injector 41 in addition to the shutoff valve 3d. The ECU 300 includes, for example, a microcomputer including a CPU, a memory for recording various programs and data, an input interface circuit, and an output interface circuit. The input interface circuit includes a temperature sensor 3b for detecting the temperature of the low-pressure gas fuel, a temperature sensor 6a for estimating the temperature of the NSR catalyst 8, an outside air temperature sensor 301 for detecting the outside air temperature, and an engine such as the engine speed and load. A load sensor 302, a rotation speed sensor 303, and the like, which are means for detecting the operating state, are connected via an electrical wiring. The output interface circuit of the ECU 300 is connected to a driving step motor SM that can open and close the shut-off valve 3d, and the opening and closing of the output interface circuit is based on the data obtained by the various sensors such as the temperature sensor 6a. It is made controllable.

  An example of the control of the gas fuel engine cooling control apparatus 101 having the above-described configuration, specifically, the control of the shut-off valve 3d in the gas fuel engine cooling control apparatus 101 will be described with reference to the flowchart of FIG. The control routine of FIG. 2 is a routine that is executed every predetermined time.

  First, in step S201, it is determined whether or not the temperature of the low-pressure gas fuel is a temperature at which the NSR catalyst 8 that is the part to be cooled can be cooled. Specifically, it is determined whether or not the temperature of the low-pressure gas fuel detected by the temperature sensor 3b is lower than the outside air temperature detected by the outside air temperature sensor 301 and the difference is, for example, 10 ° C. or more. Here, if it is determined that the temperature is 10 ° C. lower than the outside temperature, the process proceeds to step S202.

  In step S202, it is determined whether lean combustion is being performed in order to check whether NOx storage should be actively performed by the NSR catalyst 8. Whether or not lean combustion is being performed is determined by comparing the operation state of the engine 1 with data stored in a pre-mapped manner. If it is determined that lean combustion is being performed, the process proceeds to step S203.

  In step S203, in order to check whether or not the temperature of the NSR catalyst 8 is a temperature within a temperature window capable of purifying NOx determined in advance by experiments, the temperature of the NSR catalyst 8 is set to the catalyst purification rate lowering temperature. It is determined whether or not an upper limit value of the temperature window to be called is exceeded. Specifically, the acquisition temperature of the NSR catalyst 8 estimated by receiving the output signal output from the temperature sensor 6a exceeds the catalyst purification rate lowering temperature which is set to 500 ° C. in the first embodiment, for example. It is determined by whether or not it exists. When it is determined that the temperature of the NSR catalyst 8 is 500 ° C. or higher, the process proceeds to step S204 to cool the NSR catalyst 8.

  In step S204, the shut-off valve 3d is opened, the low-pressure gas fuel is allowed to flow from the low-pressure gas fuel line 32 to the cooling fuel line 3L, and the low-pressure gas fuel is also flowed to the cooling fuel line 3L. As a result, not only the low-pressure gas fuel line 32 but also the low-pressure gas fuel is caused to flow from the low-pressure gas fuel line 32 to the first cooling fuel line 33, leading to the cooled portion cooling passage 82 around the catalyst housing passage 81. The NSR catalyst 8 is cooled by the low pressure gas fuel. The low pressure gas fuel used for cooling is joined to the low pressure gas fuel flowing through the low pressure gas fuel line 32 via the second cooling fuel line 34. Note that a separate shutoff valve may be provided in the low-pressure gas fuel line 32 to completely switch the line through which the low-pressure gas fuel flows.

  Once the shutoff valve 3d is opened, the temperature of the NSR catalyst 8 begins to drop. Then, step S205 is performed so that the cooling of the NSR catalyst 8 is finished when the temperature of the NSR catalyst 8 falls below the catalyst purification rate lowering temperature, that is, within the temperature window.

  In step S205, it is determined whether cooling can be terminated, that is, whether the temperature of the NSR catalyst 8 has been lowered to a temperature within a temperature window capable of purifying NOx. Specifically, it is determined whether or not the temperature of the NSR catalyst 8 has decreased by, for example, 20 ° C. below the catalyst purification rate lowering temperature set to 500 ° C., that is, to a temperature lower than 480 ° C. If it is determined that the temperature is 480 ° C. or higher, the process returns to step S204 again, the state where the shutoff valve 3d is opened in step S204 is maintained, and the process proceeds to step S205 again. As described above, Step S204 and Step S205 are repeated, and when it is determined in Step S205 that the temperature of the NSR catalyst 8 is less than 480 ° C., the process proceeds to Step S206, the shutoff valve 3d is closed, and the cooling fuel line 3L is entered. And the cooling of the NSR catalyst 8 is terminated.

  On the other hand, if it is determined in step S202 that the lean combustion is not being performed, the process proceeds to step S207, and in order to check whether the temperature of the NSR catalyst 8 has reached the temperature at which the NSR catalyst deteriorates, the temperature of the NSR catalyst 8 is set to the catalyst durability. It is determined whether or not the catalyst referred to as the property deterioration temperature exceeds the upper limit value of the temperature at which it is difficult for the catalyst to deteriorate. Specifically, whether the temperature of the NSR catalyst 8 estimated by receiving the output signal output from the temperature sensor 6a exceeds the catalyst durability deterioration temperature, which is 700 ° C. in the first embodiment, for example. It is determined by whether or not. When the temperature of the NSR catalyst 8 is 700 ° C. or higher, the process proceeds to step S208 to cool the NSR catalyst 8, and the shut-off valve 3d is opened.

  In step S209, in order to check whether the cooling can be completed, that is, whether the temperature of the NSR catalyst 8 is cooled to a temperature at which it is difficult to deteriorate, the temperature of the NSR catalyst 8 is, for example, 20 ° C. higher than the catalyst durability deterioration temperature. It is determined whether the temperature is lower than 680 ° C., which is a low temperature. Then, similarly to Step S204 and Step S205, Step S208 and Step S209 are repeated until the temperature of the NSR catalyst becomes lower than 680 ° C. As a result, when it is determined in step S209 that the temperature of the NSR catalyst 8 is less than 680 ° C., the process proceeds to step S206, the shutoff valve 3d is closed, and the cooling of the NSR catalyst 8 is finished.

  By repeatedly performing the control as described above, for example, the temperature of the NSR catalyst 8 is maintained at a temperature at which NOx occlusion and reduction can be appropriately performed without a cooling source other than the essential gas fuel. . In particular, since this is controlled to be performed during lean combustion, it becomes possible to occlude NOx accurately during lean combustion. Since NOx occlusion in the NSR catalyst 8 is particularly required during lean combustion, the control of the shut-off valve 3d is executed focusing on the lean combustion, but the present invention is not limited to this. .

  Next, a second embodiment of the cooling control apparatus for a gas fuel engine according to the present invention will be described based on FIG. 3 and FIG. FIG. 3 is a schematic diagram for explaining the cooling control apparatus 102 for the gas fuel engine according to the second embodiment, and FIG. 4 is a flowchart for controlling the cooling control apparatus 102 for the gas fuel engine in FIG. It is an example. In order to facilitate understanding of the description, the same components as those in the first embodiment are denoted by the same reference numerals as much as possible to avoid redundant description.

  The second embodiment is different from the first embodiment in that there is no cooling fuel line 3L branched from the low-pressure gas fuel line 32 and joined again. Instead, in the second embodiment, the heat exchanger 9 is disposed around the low-pressure gas fuel line 32, and the circulation pump 10a circulates the refrigerant between the heat exchanger 9 and the cooled portion cooling passage 82. Is provided with a refrigerant line 10. Hereinafter, these points will be described in detail.

  The low-pressure gas fuel line 32 downstream of the regulator 3 a is connected to the delivery pipe 4 via a passage 91 in the heat exchanger 9. That is, the heat exchanger 9 is disposed around the low-pressure gas fuel line 32. On the other hand, the refrigerant line 10 similarly passes through a passage 92 in the heat exchanger 9 and is connected to a cooled portion cooling passage 82. In other words, the refrigerant line 10 forms a closed flow path by the passage 92 and the cooled portion cooling passage 82, and the low-pressure gas fuel line 32 and the refrigerant line 10 exchange heat with each other in the heat exchanger 9. Has been made possible. That is, the low-temperature low-pressure gas fuel flows through the low-pressure gas fuel line 32, and the refrigerant in the refrigerant line 10 is cooled in the heat exchanger 9. The refrigerant in the refrigerant line 10 is circulated by the circulation pump 10a, so that the NSR catalyst 8 can be cooled as in the first embodiment. Note that the output interface circuit of the ECU 300 is connected to the circulation pump 10a in order to control the circulation pump 10a. The operation can be controlled based on data obtained by the temperature sensor 6a, the temperature sensor 6b disposed in the third exhaust pipe 63 in the second embodiment, and the like.

  A flowchart of FIG. 4 shows an example of the control of the cooling control apparatus 102 for the gas fuel engine in the second embodiment having the above-described configuration, specifically, an example of the control of the circulation pump 10a. In the control example shown in the flowchart of FIG. 4, “open the shut-off valve 3d” in steps S204 and S208 of the flowchart of FIG. 2 in the first embodiment described above is described as “circulation pump 10a” in steps S404 and S408. The control example shown in the flowchart of FIG. 2 is the point that “closes the shut-off valve 3d” in step S206 becomes “turns off the circulation pump 10a” in step S406. Therefore, the description here is omitted with reference to the flowchart of the first embodiment of FIG. The difference between the first embodiment and the first embodiment is that the switching valve 3d is used to change whether or not the low-pressure gas fuel as the refrigerant is allowed to flow through the cooled portion cooling passage 82. In the second embodiment, the refrigerant is circulated by the circulation pump 10a. Further, steps S401 to S403, S405, S407, and S409 in the second embodiment correspond to steps S201 to S203, S205, S207, and S209 in the first embodiment.

  As described above, also in the second embodiment, as in the first embodiment, for example, the temperature of the NSR catalyst 8 is maintained at a temperature at which NOx occlusion and reduction can be appropriately performed. In particular, since this is controlled to be performed during lean combustion, it becomes possible to occlude NOx accurately during lean combustion.

  In addition, according to the second embodiment, since the low-pressure gas fuel supply line 32 is only extended to the heat exchanger 9, the flow of the low-pressure gas fuel flows as compared with the first embodiment. The road can be shortened.

  Next, a third embodiment of the cooling control apparatus for a gas fuel engine according to the present invention will be described with reference to FIGS. FIG. 5 is a schematic diagram for explaining the cooling control apparatus 103 for the gas fuel engine according to the third embodiment, and FIG. 6 is a flowchart for controlling the cooling control apparatus 103 for the gas fuel engine in FIG. It is an example. In order to facilitate the understanding of the description, the same reference numerals are given to the same components as those in the first embodiment and the second embodiment as much as possible, and a duplicate description is avoided.

  Similar to the second embodiment, the third embodiment differs from the first embodiment in that it does not have the cooling fuel line 3L branched from the low-pressure gas fuel line 32 and joined again. . Further, the third embodiment is different from the second embodiment in that the heat exchanger 9 is not provided. Instead, in the third embodiment, the circulation pump 11a is disposed so as to allow the refrigerant to circulate through the cooled portion cooling passage 82 and the refrigerant passage 3f disposed in the regulator 3a. The refrigerant line 11 is provided. Hereinafter, these points will be described in detail.

  As described above, the low-pressure gas fuel line 32 is arranged to flow the low-pressure gas fuel decompressed by the regulator 3a to the connected delivery pipe 4. On the other hand, the refrigerant line 11 is connected to a refrigerant passage 3f disposed in the regulator 3a so as to circulate in the regulator 3a. It is also connected to a cooled part cooling passage 82. In other words, the refrigerant line 11 forms a closed flow path by the refrigerant passage 3f and the cooled portion cooling passage 82, and for example, the low-pressure gas fuel line 32 and the refrigerant line 11 exchange heat with each other in the regulator 3a. Has been made possible. Specifically, when the high pressure gas fuel in the fuel tank 31 is changed to low pressure gas fuel by the regulator 3a, the refrigerant in the refrigerant line 11 is cooled by the low pressure gas fuel that has become low temperature or the regulator 3a that is cooled accordingly. To be cooled. The refrigerant in the refrigerant line 11 is circulated by the circulation pump 11a, so that the NSR catalyst 8 can be cooled as in the first embodiment and the second embodiment.

  Next, an example of the control of the cooling control apparatus 103 for the gas fuel engine in the third embodiment, specifically, an example of the control of the circulation pump 11a is shown in the flowchart of FIG. The control example shown in the flowchart of FIG. 6 is different from the control example shown in the flowchart of FIG. 4 of the second embodiment only in that step S401 is not present. Omitted. Note that steps S601 to S608 in the third embodiment correspond to steps S402 to S409 in the second embodiment.

  As described above, also in the third embodiment, similarly to the first embodiment and the second embodiment, for example, the temperature of the NSR catalyst 8 is maintained at a temperature at which NOx occlusion and reduction can be appropriately performed. It will be. In particular, since this is controlled to be performed during lean combustion, it becomes possible to occlude NOx accurately during lean combustion.

  Further, according to the third embodiment, since the low-pressure gas fuel supply line 32 is not extended at all, the flow path through which the low-pressure gas fuel flows is further shortened as compared with the first and second embodiments. Is possible.

  Incidentally, in the first to third embodiments, the cooled portion is the NSR catalyst 8 provided in the exhaust passage 6, but the present invention is not limited to this. For example, an intake passage and It is also possible to do. Hereinafter, an embodiment of a cooling control apparatus for a gas fuel engine according to the present invention, in which the part to be cooled is an intake passage, will be described. However, in the fourth to sixth embodiments shown below, it is generally the first to the above-mentioned that the cooled portion cooling passage is disposed around the intake manifold as a cooled portion as an intake passage, more specifically, an intake manifold. Only the third embodiment is different from the third embodiment, and other configurations are substantially the same as the corresponding first to third embodiments. Therefore, in order to facilitate the understanding of the description, the same components as those in the first to third embodiments are denoted by the same reference numerals as much as possible to avoid redundant description.

  Accordingly, a fourth embodiment of the cooling control apparatus for a gas fuel engine according to the present invention will be described with reference to FIGS. FIG. 7 is a schematic diagram for explaining the cooling control apparatus 104 for the gas fuel engine according to the fourth embodiment, and FIG. 8 is a flowchart for controlling the cooling control apparatus 104 for the gas fuel engine in FIG. It is an example. The configuration is substantially the same as that of the first embodiment except that the cooled portion is an intake manifold and the cooled portion cooling passage is disposed around the intake manifold.

  In the fourth embodiment, a cooled portion cooling passage 21 is disposed around the intake manifold 2 in the vicinity of an intake pipe (not shown) connected to the intake manifold 2. That is, the intake manifold 2 has a double structure. The first cooling fuel line 33 and the second cooling fuel line 34 are connected to the cooled part cooling passage 21, and the low pressure gas fuel flowing into the cooled part cooling passage 21 from the first cooling fuel line 33 is It flows out to the second cooling fuel line 34. Of the intake passages that are cooled parts, only the intake manifold 2 has a double structure. However, any part of the intake passages up to the intake port has a double structure, and the cooling part cooling passages are arranged. It is good also to install.

  Further, an intake air temperature sensor 304 for detecting the intake air temperature and a water temperature sensor 305 for detecting the temperature of the engine coolant are provided, and these are connected to the input interface circuit of the ECU 300. Further, the ECU 300 is preliminarily obtained through experiments to estimate the temperature of the intake manifold 2 that is a part to be cooled from the intake air temperature detected by the intake air temperature sensor 304 and the temperature of engine cooling water detected by the water temperature sensor 305. Stored data is stored.

  An example of control of the cooling control device 104 for the gas fuel engine having the above-described configuration, specifically, control of the shut-off valve 3d in the cooling control device 104 for the gas fuel engine will be described with reference to the flowchart of FIG. The control routine of FIG. 8 is a routine that is executed every predetermined time.

  First, in step S801, whether or not the low-pressure gas fuel is at a temperature at which the intake manifold 2 that is a cooled portion can be cooled, specifically, the temperature of the low-pressure gas fuel detected by the temperature sensor 3b is an intake air temperature sensor. It is determined whether the intake air temperature is lower than that detected by 304 and the difference is, for example, 10 ° C. or more. If it is determined that the temperature is 10 ° C. or more lower than the intake air temperature, the process proceeds to step S802 to cool the portion to be cooled.

  Next, in step S802, in order to prevent the intake air from being excessively cooled and the mixing of the air-fuel mixture to be deteriorated to deteriorate the engine performance, it is determined whether or not the cooling is an unnecessary cooling condition in which the intake air is not cooled. . Specifically, the engine coolant temperature detected by the water temperature sensor 305 is more than 80 ° C., for example, in order to prompt the engine 1 to be warmed up to a state where the low-pressure gas fuel is combusted properly. Whether the engine is warming up is determined based on whether the engine is low. If it is determined that the cooling unnecessary condition is not satisfied, that is, the temperature of the engine cooling water is 80 ° C. or higher, the process proceeds to step S803. Here, the determination as to whether or not the temperature of the engine cooling water is lower than, for example, 80 ° C. is connected to the engine 1 because the intake air 2 is being cooled by cooling the intake manifold 2 that is the part to be cooled. This corresponds to whether or not the temperature of the intake manifold 2 is lower than a predetermined temperature. Therefore, in step S802, the control for changing the flow rate distribution of the low-pressure gas fuel from the low-pressure gas fuel line 32 to the cooling fuel line 3L based on the water temperature of the engine cooling water is performed based on the water temperature of the engine cooling water. This means that the control is performed based on the temperature of the intake manifold 2 that can be estimated, that is, whether the acquired temperature of the intake manifold 2 is equal to or higher than a predetermined value or lower than a predetermined value. In addition, it is good also as determining whether it is applicable to cooling unnecessary conditions by whether an intake air temperature is lower than 0 degreeC. In this case, it corresponds to determining whether the temperature of the intake manifold 2 is lower than a predetermined temperature from the intake air temperature and the engine coolant temperature.

  In step S803, it is determined whether or not a high-load operation is being performed. Specifically, whether or not to supercharge for the purpose of increasing the output is determined by whether or not the load detected by the load sensor 302 or the like is a high load. If it is determined that the vehicle is operating at a high load, the process proceeds to step S804.

  In step S804, the shutoff valve 3d is opened to cool the intake manifold 2 by flowing low-pressure gas fuel through the cooling fuel line 3L. As a result, the low-pressure gas fuel also flows from the low-pressure gas fuel line 32 to the first cooling fuel line 33, and the intake manifold 2 is cooled by the low-pressure gas fuel that reaches the cooled portion cooling passage 21. As a result, the intake air is cooled and contracts in volume, and a larger amount of intake air is supercharged to the combustion chamber 11 to increase the intake charge efficiency. The low-pressure gas fuel used for cooling is joined to the low-pressure gas fuel flowing through the low-pressure gas fuel line 32 via the second cooling fuel line 34.

  If it is determined in step S801 that the temperature is not coolable, the cooling is not required in step S802, or the high load operation is not determined in step S803, the shutoff valve 3d is closed in step S805.

  By repeatedly performing the above control, the intake manifold 2 is cooled without any other cooling source other than the essential gas fuel, and as a result, the intake air is appropriately cooled.

  Next, a fifth embodiment of the cooling control apparatus for a gas fuel engine according to the present invention will be described based on FIG. 9 and FIG. FIG. 9 is a schematic view for explaining the gas fuel engine cooling control apparatus 105 of the fifth embodiment, and FIG. 10 is a flowchart for controlling the gas fuel engine cooling control apparatus 105 in FIG. It is an example.

  The fifth embodiment is different from the second embodiment in that the portion to be cooled is an intake manifold and a cooling portion cooling passage is disposed around the intake manifold. This embodiment is different from the embodiment in that the cooling fuel line 3L branched from the low-pressure gas fuel line 32 and joined again is not provided.

  The low-pressure gas fuel line 32 is connected to the delivery pipe 4 via a passage 91 in the heat exchanger 9. On the other hand, the refrigerant line 10 is connected to the cooled portion cooling passage 21 through the passage 92 in the heat exchanger 9 in the same manner. In other words, the refrigerant line 10 forms a closed flow path by the passage 92 and the cooled portion cooling passage 21, and the low-pressure gas fuel line 32 and the refrigerant line 10 exchange heat with each other in the heat exchanger 9. Has been made possible. The cooled refrigerant in the refrigerant line 10 is circulated by the circulation pump 10a, so that the intake manifold 2 can be cooled.

  Next, FIG. 10 shows an example of the control of the cooling control device 105 for the gas fuel engine having the above configuration, specifically, the control of the circulation pump 10a for the cooling control device 105 of the gas fuel engine. The flowchart of FIG. 10 is the same as the flowchart of FIG. 8 of the fourth embodiment, but “open the shut-off valve 3d” in step S804 and “close the shut-off valve 3d” in step S805 are the same as “circulation pump 10a in step S1004”. The only difference is that “turn ON” and “turn OFF circulation pump 10a” in step S1005, and the description thereof will be omitted. This difference is caused by the same reason as the difference in the control example of the first embodiment and the second embodiment. Steps S1001 to S1003 in the fifth embodiment correspond to steps S801 to S803 in the fourth embodiment.

  Next, a sixth embodiment of the cooling control apparatus for a gas fuel engine according to the present invention will be described with reference to FIGS. FIG. 11 is a schematic view for explaining the gas fuel engine cooling control device 106 according to the sixth embodiment, and FIG. 12 is a flowchart for controlling the gas fuel engine cooling control device 106 in FIG. It is an example.

  The sixth embodiment is different from the third embodiment in that the portion to be cooled is an intake manifold and a cooling portion cooling passage is disposed around the intake manifold. This embodiment is different from the above embodiment in that the cooling fuel line 3L branched from the low-pressure gas fuel line 32 and joined again is not provided. Furthermore, the fifth embodiment is different from the fifth embodiment in that the heat exchanger 9 is not provided.

  As described above, the low-pressure gas fuel line 32 is arranged to flow the low-pressure gas fuel decompressed by the regulator 3a to the connected delivery pipe 4. On the other hand, the refrigerant line 11 is connected to a refrigerant passage 3f disposed in the regulator 3a so as to circulate in the regulator 3a. It is also connected to a cooled part cooling passage 21. As a result, the refrigerant in the refrigerant line 11 is cooled in the regulator 3 a that uses the high-pressure gas fuel in the fuel tank 31 as the low-pressure gas fuel. Then, the refrigerant in the refrigerant line 11 is circulated by the circulation pump 11a, and the intake manifold 2 is cooled.

  Next, FIG. 12 shows an example of the control of the cooling control device 106 of the gas fuel engine having the above configuration, specifically, the control of the circulation pump 11a in the cooling control device 106 of the gas fuel engine. The flowchart of FIG. 12 is different from the flowchart of FIG. 10 of the fifth embodiment only in that step S1001 is not provided, and thus description of this control example is omitted. Note that steps S1201 to S1204 in the sixth embodiment correspond to steps S1002 to S1005 in the fifth embodiment.

  As mentioned above, although the cooling control apparatus of the gas fuel engine which concerns on this invention was demonstrated based on 6th embodiment from 1st embodiment, this invention is not limited to these. Specifically, in the cooling control device for one gas fuel engine, both the NSR catalyst provided in the exhaust passage and the intake passage may be cooled. In each step of the control of the first embodiment, the temperature that serves as a criterion for determination can be arbitrarily set. Furthermore, the passages 91 and 92 of the heat exchanger 9 and the refrigerant passage 3f of the regulator 3a may have an arbitrary mechanism as long as the refrigerant can be cooled with low-pressure gas fuel or the like, and may follow an arbitrary path. Technology can be used.

It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 1st embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG. It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 2nd embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG. It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 3rd embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG. It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 4th embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG. It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 5th embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG. It is the schematic for demonstrating the cooling control apparatus of the gas fuel engine of 6th embodiment. It is an example of the flowchart for controlling the cooling control apparatus of the gas fuel engine in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 11 Combustion chamber 12 Piston cavity 2 Intake manifold 21 Cooling part cooling passage 3 Gas fuel supply system 31 Fuel tank 32 Low pressure gas fuel line 33 First cooling fuel line 34 Second cooling fuel line 3L Cooling fuel line 3a Regulator 3b Temperature sensor 3c Check valve 3d Shut-off valve 3e Check valve 3f Refrigerant passage 4 Delivery pipe 41 CNG direct injection injector 5 Exhaust manifold 6 Exhaust pipe 61 First exhaust pipe 62 Second exhaust pipe 63 Third exhaust pipe 7 Three-way catalyst 8 NSR catalyst 81 Catalyst housing passage 82 Cooled part cooling passage 9 Heat exchanger 91 Passage 92 Passage 10 Refrigerant line 10a Circulating pump 11 Refrigerant line 11a Circulating pump 300 ECU

Claims (7)

A gas fuel engine cooling control device comprising a low-pressure gas fuel line that depressurizes high-pressure gas fuel in a fuel tank with a regulator and supplies the injectors to each injector via a delivery pipe,
A cooled part temperature acquisition means for detecting or estimating the temperature of the cooled part;
A passage for cooling a portion to be cooled disposed in the portion to be cooled;
Cooling fuel that is branched from the low-pressure gas fuel line downstream of the regulator, communicates with the delivery pipe or the low-pressure gas fuel line upstream thereof via the cooled portion cooling passage, and includes a check valve that prevents backflow Line,
Changing means for changing the flow distribution from the low-pressure gas fuel line to the cooling fuel line;
When the temperature acquired by the to-be-cooled part temperature acquisition unit exceeds a predetermined value, the change unit allows the flow from the low-pressure gas fuel line to the cooling fuel line, and the acquired temperature is less than the predetermined value. In this case, the control means for controlling the flow to the cooling fuel line by the changing means,
A cooling control device for a gas fuel engine, comprising: A gas fuel engine cooling control device comprising a low-pressure gas fuel line that depressurizes high-pressure gas fuel in a fuel tank with a regulator and supplies the injectors to each injector via a delivery pipe,
A cooled part temperature acquisition means for detecting or estimating the temperature of the cooled part;
A passage for cooling a portion to be cooled disposed in the portion to be cooled;
A heat exchanger disposed around a low pressure gas fuel line downstream of the regulator;
Refrigerant is circulated through the cooled part cooling passage and the heat exchanger, and a refrigerant line in which a circulation pump is disposed;
When the temperature acquired by the cooled part temperature acquisition means exceeds a predetermined value, the circulation pump is operated, and when the acquired temperature is less than the predetermined value, the operation of the circulation pump is stopped. Control means for controlling;
A cooling control device for a gas fuel engine, comprising: A gas fuel engine cooling control device comprising a low-pressure gas fuel line that depressurizes high-pressure gas fuel in a fuel tank with a regulator and supplies the injectors to each injector via a delivery pipe,
A cooled part temperature acquisition means for detecting or estimating the temperature of the cooled part;
A passage for cooling a portion to be cooled disposed in the portion to be cooled;
Refrigerant is circulated through the cooling portion cooling passage and the refrigerant passage disposed in the regulator, and a refrigerant line in which a circulation pump is disposed;
When the temperature acquired by the cooled part temperature acquisition means exceeds a predetermined value, the circulation pump is operated, and when the acquired temperature is less than the predetermined value, the operation of the circulation pump is stopped. Control means for controlling;
A cooling control device for a gas fuel engine, comprising:   4. The gas fuel engine cooling control apparatus according to claim 1, wherein the cooled portion is a NOx occlusion reduction type catalyst provided in an exhaust passage.   4. The cooling control apparatus for a gas fuel engine according to claim 1, wherein the portion to be cooled is an intake passage.   5. The cooling control apparatus for a gas fuel engine according to claim 4, wherein the control of the changing means by the control means is executed only during lean combustion.   5. The cooling control apparatus for a gas fuel engine according to claim 4, wherein the control of the circulation pump by the control means is executed only during lean combustion.

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