JP2018168748A - Engine apparatus - Google Patents

Abstract

To prevent the freezing of a carburetor.SOLUTION: An engine apparatus 200 comprises: an engine 1; and a carburetor 101 vaporizing liquefied fuel gas from a fuel gas source 100, and causes a part of cooling water for the engine 1 to flow into the carburetor 101. The engine apparatus 200 further comprises: a water-cooled exhaust manifold 6 having a cooling water passage 82 for cooling an exhaust gas passage 81; a feed bypass pathway 96 connecting a water outlet 84 of the water-cooled exhaust manifold 6 to a water inlet 102 of the carburetor 101; a return bypass pathway 108 connecting a water outlet 103 of the carburetor 101 to a water inlet 83 of the water-cooled exhaust manifold 6; a circulation pump 109 provided in the bypass pathway 108; and a pathway switching mechanism for switching between a warming pathway 88 for connecting the carburetor 101 to a water outlet 85 for the carburetor of the engine 1 and a water inlet 86 for the carburetor of the engine 1 and a circulation pathway 90 returning from the carburetor 101 to the carburetor 101 again through the bypass pathways 96, 108, the circulation pump 109 and the water-cooled exhaust manifold 6.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an engine device that rotates an output shaft based on combustion by fuel gas.

  Conventionally, there has been provided a gas engine that is driven by igniting an air-fuel mixture of fuel gas and air with an ignition device (ignition plug) (see, for example, Patent Document 1). In the gas engine of Patent Literature 1, cooling water is circulated through a vaporizer that vaporizes liquefied gas from a liquefied gas source that stores liquefied fuel gas. Circulation of the cooling water to the vaporizer is performed by using a part of the cooling water heated through the inside of the engine in order to prevent the vaporizer from freezing and to stably vaporize the fuel.

JP-A-7-293345

  However, in the engine device described in the above prior art, the cooling water is cooled even when the engine is started at a low temperature start, and the vaporizer freezes due to a decrease in the temperature of the vaporizer body due to fuel vaporization heat, and the liquefied fuel gas is There was a problem that the engine could stall without being vaporized.

  This invention makes it a technical subject to provide the engine apparatus which examined and improved the above present condition.

  An engine apparatus according to the present invention is an engine apparatus that includes an engine and a vaporizer that vaporizes liquefied fuel gas from a fuel gas source that stores the liquefied fuel gas, and distributes a part of engine cooling water to the vaporizer. A water-cooled exhaust manifold having a cooling water passage for cooling the exhaust gas passage, a feed bypass passage for connecting a water outlet of the water-cooled exhaust manifold to a water inlet of the carburetor, and a water outlet of the carburetor for the water-cooled exhaust manifold A return bypass path connected to the water inlet of the engine, a circulation pump provided in the bypass path, a heating path connecting the vaporizer to the water outlet for the vaporizer of the engine and the water inlet for the vaporizer, and the vaporizer Path switching machine for switching from the bypass path, the circulation pump and the circulation path returning to the carburetor again through the water-cooled exhaust manifold It is one that is equipped with a.

  In the engine device of the present invention, for example, when the cooling water temperature and the intake air temperature of the engine are each equal to or less than a predetermined threshold value, the path switching mechanism forms the circulation path, while the circulation pump is driven to The cooling water may be circulated through the circulation path.

  In the engine device of the present invention, for example, when the air-fuel ratio of the mixture of fuel gas and air of the engine tends to be leaner than a predetermined threshold, the path switching mechanism forms the circulation path. On the other hand, the circulating pump may be driven to circulate cooling water through the circulation path.

  The engine device of the present invention has a heating path that connects the carburetor to the carburetor water outlet and the carburetor water inlet of the engine, and a circulation that returns from the carburetor to the carburetor through the bypass path, the circulation pump, and the water-cooled exhaust manifold. Since the cooling water is forced to circulate by the circulation pump in the above circulation path, the cooling in the water-cooled exhaust manifold is likely to become faster than the cooling water inside the engine after the engine is started. Water can be supplied directly to the vaporizer. Further, by controlling the discharge amount of the circulation pump, the cooling water that has passed through the water-cooled exhaust manifold can be reliably supplied to the vaporizer at a desired flow rate. Thereby, when freezing of the carburetor is predicted, such as at a low temperature start, the freezing of the carburetor can be suppressed, the engine stall caused by the freezing of the carburetor can be prevented, and the engine startability can be improved.

  In the engine device of the present invention, for example, when the cooling water temperature and the intake air temperature of the engine are each equal to or less than a predetermined threshold value, the path switching mechanism forms the circulation path, while the circulation pump is driven to If the cooling water is circulated in the circulation path, it is possible to predict the freezing of the carburetor using the existing cooling water temperature sensor, intake air temperature sensor, etc., and it is not necessary to provide a dedicated temperature sensor or the like in the carburetor. A more inexpensive configuration can be used to suppress an increase in the manufacturing cost of the engine device.

  In the engine device of the present invention, for example, when the air-fuel ratio of the mixture of fuel gas and air of the engine tends to be leaner than a predetermined threshold, the path switching mechanism forms the circulation path. On the other hand, if the circulation pump is driven to circulate the cooling water in the circulation path, the liquefied fuel gas is less likely to vaporize if the vaporizer tends to freeze, and the air-fuel ratio tends to be lean. It is possible to predict the freezing of the vaporizer by using the characteristic that becomes. Therefore, there is no need to provide a dedicated temperature sensor or the like in the carburetor, so that it is possible to suppress the increase in the manufacturing cost of the engine device by using a cheaper configuration.

It is the schematic perspective view seen from the right front of the engine of one embodiment. It is the schematic perspective view which looked at the engine from the left rear. It is a schematic perspective view which expands and shows the same engine. It is a schematic perspective view which shows the engine apparatus of one Embodiment. It is a schematic sectional drawing of an exhaust manifold. It is a schematic block diagram which shows the cooling water system | strain of an engine apparatus. It is a flowchart which shows the vaporizer freezing prevention control of the same engine apparatus. It is a schematic block diagram which shows the cooling water system | strain of the engine apparatus of other embodiment. It is a flowchart which shows the vaporizer freezing prevention control of the same engine apparatus. It is a schematic block diagram which shows the cooling water system | strain of the engine apparatus of other embodiment. It is a schematic block diagram which shows the cooling water system | strain of the engine apparatus of other embodiment.

  Below, engine device 200 of one embodiment which materialized the present invention is explained based on a drawing. The engine device 200 includes an engine 1 including a gas engine and a vaporizer (vaporizer) 101. In the following description, when terms (for example, “left and right”, “up and down”, etc.) indicating a specific direction or position are used as necessary, the intake manifold 3 side of the engine 1 is set to the left side of the engine 1 and the engine 1 is set. The exhaust manifold 6 side is expressed as the right side of the engine 1, the flywheel housing 7 side is expressed as the front side of the engine 1, and the transmission belt 18 side is expressed as the rear side of the engine 1. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

  The engine 1 is driven by a premixed combustion method in which fuel gas such as natural gas is mixed with air and burned. As shown in FIGS. 1 to 3, an intake manifold 3 is provided on the left side surface of the cylinder head 2 located at the top of the engine 1. The cylinder head 2 is mounted on a cylinder block 5 containing an engine output shaft 4 (crankshaft) and a plurality of cylinders (not shown). An exhaust manifold 6 is provided on the right side surface of the cylinder head 2. The front and rear projecting ends of the engine output shaft 4 are projected from both front and rear side surfaces of the cylinder block 5.

  The engine 1 has a configuration in which a plurality of cylinders are arranged in series in a cylinder block 5. Each cylinder in the cylinder block 5 communicates with the intake manifold 3 on the left side of the cylinder head 2. Although not shown in detail, an air cleaner is connected to the intake manifold 3 through an intake throttle valve 11 to clean up and take in outside air. Further, an ignition device 12 for igniting the premixed gas in each cylinder is provided corresponding to each cylinder on the upper left portion (on the intake manifold 3 side) of the cylinder head 2. Each ignition device 12 generates a spark discharge in the cylinder by a high voltage, and burns the premixed gas in the cylinder. The piston in each cylinder reciprocates due to the combustion of the premixed gas, rotationally drives the engine output shaft 4, and the power of the engine 1 is generated.

  The intake manifold 3 fixed to the left side surface of the cylinder head 2 includes the same number of intake branch pipes 31 as the number of cylinders, and a gas injector 13 is inserted into each intake branch pipe 31. The same number of gas injectors 13 as the number of cylinders are connected to a fuel gas supply rail 14 extending forward and backward (parallel to the engine output shaft 4) above the intake manifold 3. The fuel gas supply rail 14 is fixedly fastened to the intake manifold 3 by bolts 21.

  As shown in FIG. 4, the gas inlet 28 of the fuel gas supply rail 14 is connected to the gas cylinder 100 via the vaporizer 101. Liquid fuel gas is stored in the gas cylinder 100, and after the fuel gas in the gas cylinder 100 is vaporized by the vaporizer 101, it is supplied to the gas injector 13 through the fuel gas supply rail 14. When the gas injector 13 injects fuel gas into the intake branch pipe 31, fresh air and fuel gas in the intake manifold 3 are mixed and stirred in the intake branch pipe 31, and each cylinder in the cylinder block 5 is mixed and stirred. Supplied to the intake port. Each cylinder in the cylinder block 5 communicates not only with the intake manifold 3 but also with an exhaust manifold 6 fixed to the right side of the cylinder head 2, and exhaust gas is supplied to the exhaust manifold 6 through an exhaust port in each cylinder. Exhausted.

  A right upper surface of the cylinder head 2 is covered with a head cover 15, and a valve arm chamber (not shown) is formed in the head cover 15. A plurality of ignition devices 12 are inserted side by side on the left side portion of the upper surface of the cylinder head 2 that is not covered with the head cover 15 (the exposed portion of the upper surface of the cylinder head 2). In addition, an intake valve, an exhaust valve (not shown), and the like are covered with a head cover 15 on the right side of the upper surface of the cylinder head 2.

  A blow-by gas reduction device 16 that separates lubricating oil from blow-by gas leaking from the combustion chambers of the cylinders and the like to the upper surface side of the cylinder head 2 is configured at the rear portion of the head cover 15. The blow-by gas reduction device 16 communicates with the intake manifold 3 via a blow-by gas return pipe 17. When blow-by gas leaking from the combustion chambers configured in the cylinder head 2 and the cylinder block 5 is supplied to the intake manifold 3 through the blow-by gas reduction device 16 and the blow-by gas return pipe 17, the intake air is taken in via the intake throttle valve 11. The fresh air supplied to the manifold 3 joins. The blow-by gas that has joined the fresh air in the intake manifold 3 is retransmitted (reduced) to the combustion chamber, so that the blow-by gas is not released into the atmosphere.

  The engine 1 includes a cooling water pump 19 that circulates cooling water in the cylinder head 2 and the cylinder block 5, a radiator (not shown), and the like, and an alternator 20 that charges a battery (not shown). A cooling water pump 19 and an alternator 20 are connected to the left protruding end of the engine output shaft 4 via a transmission belt 18 and the like. The rotational power of the engine output shaft 4 is transmitted to the cooling water pump 19 via the transmission belt 18 to drive the cooling water pump 19, and the cooling water is circulated in the cylinder head 2 and the cylinder block 5, the radiator and the like. On the other hand, the rotational power of the engine output shaft 4 is transmitted to the alternator 20 via the transmission belt 18 to drive the alternator 20, and the battery (not shown) is charged by the electric power generated by the alternator 20. In the embodiment, the cooling water pump 19 is attached to the rear upper part of the engine 1, and the alternator 20 is attached to the rear right part of the engine 1.

  As shown in FIG. 5, the exhaust manifold 6 is a water-cooled exhaust manifold. That is, the exhaust manifold 6 includes an exhaust gas passage 81 that communicates with each cylinder in the cylinder block 5 via the cylinder head 2 and a cooling water passage 82 that cools the exhaust gas passage 81. Exhaust gas discharged from each cylinder of the engine 1 is discharged from the right side surface of the cylinder head 2. As indicated by broken line arrows, the exhaust gas is taken into the exhaust gas passage 81 of the exhaust manifold 6 and joined, and then discharged from the exhaust gas outlet at the front of the exhaust manifold 6. The exhaust gas discharged from the exhaust manifold 6 is discharged to the outside through an exhaust gas purification device (not shown).

  Cooling water is introduced into the upstream portion (front portion) of the cooling water passage 82 from a water inlet 83 provided at the lower front end portion of the exhaust manifold 6. The introduced cooling water flows in the cooling water passage 82 toward the rear of the engine 1 while being in contact with the outer wall of the exhaust gas passage 81 as indicated by solid arrows. The cooling water that has reached the downstream portion (rear portion) of the cooling water passage 82 flows out of the cooling water passage 82 from a water outlet 84 provided at the upper rear end portion of the exhaust manifold 6.

  As shown in FIG. 6, in this embodiment, the water inlet 83 of the exhaust manifold 6 is connected to a cooling water passage inside the cylinder block 5 via an upstream water passage 91. Further, the water outlet 84 of the exhaust manifold 6 is connected to the cooling water pump 19 via the downstream water path 92. By driving the cooling water pump 19, the cooling water is circulated through the cylinder head 2 (see FIG. 1 and the like) and the cooling water passages inside the cylinder block 5, thereby cooling the engine 1.

  A part of the cooling water flowing through the cooling water passage inside the cylinder block 5 is introduced into the cooling water passage 82 via the upstream water passage 91 and the water inlet 83 of the exhaust manifold 6, and passes through the exhaust gas passage 81. Cool the circulating exhaust gas. The cooling water that has passed through the cooling water passage 82 flows into the cooling water pump 19 through the water outlet 84 and the downstream water passage 92.

  As shown in FIGS. 4 and 6, the cooling water pump 19 of the engine 1 is provided with a vaporizer water outlet 85 and a vaporizer water inlet 86. The vaporizer water outlet 85 is connected to the water inlet 102 of the vaporizer 101 via a vaporizer water feed path 93. The vaporizer water inlet 86 is connected to the water outlet 103 of the vaporizer 101 through a vaporizer water return path 94. By driving the cooling water pump 19, a part of the cooling water that has passed through the engine 1 is circulated to the vaporizer 101. As a result, the vaporizer 101 is heated to prevent the vaporizer 101 from freezing, and the fuel vaporization in the vaporizer 101 is stabilized.

  The liquefied fuel gas inlet 104 of the vaporizer 101 is connected to a gas cylinder 100 as an example of a fuel gas source via a liquefied fuel gas path 106 made of piping. Further, the fuel gas outlet 105 of the vaporizer 101 is connected to the gas inlet 28 of the engine 1 via a fuel gas path 107 made of piping. The liquefied fuel gas supplied from the gas cylinder 100 is introduced into the vaporizer 101 from the liquefied fuel gas inlet 104 via the liquefied fuel gas path 106 and is vaporized by the vaporizer 101. The fuel gas vaporized by the vaporizer 101 is sent from the fuel gas outlet 105 to the gas inlet 28 of the engine 1 through the fuel gas path 107.

  As shown in FIG. 6, a feed bypass path 96 is provided for connecting the water outlet 84 of the exhaust manifold 6 to the water inlet 102 of the vaporizer 101 without passing through the cooling water flow path inside the engine 1. One end (upstream end) of the feed bypass path 96 is connected to a midway part of the downstream water path 92 communicating with the water outlet 84 of the exhaust manifold 6 via a switching valve 95 made of, for example, a three-way valve. The other end (downstream end) of the feed bypass path 96 is connected to a midway portion of the water feed path 93 that communicates with the water inlet 102 of the vaporizer 101.

  In addition, a return bypass path 108 is provided for connecting the water outlet 103 of the vaporizer 101 to the water inlet 83 of the exhaust manifold 6 without passing through the cooling water flow path inside the engine 1. One end (upstream end) of the return bypass path 108 is connected to a midway portion of the water return path 94 communicating with the water outlet 103 of the vaporizer 101 via a switching valve 98 made of, for example, a three-way valve. The other end (downstream end) of the return bypass path 108 is connected to a midway portion of the upstream water path 91 communicating with the water inlet 83 of the exhaust manifold 6 via a switching valve 99 made of, for example, a three-way valve. . A circulation pump 109 is provided in the middle of the return bypass path 108. The circulation pump 109 is constituted by, for example, an electric liquid feed pump, sucks cooling water from the switching valve 98 side, and discharges cooling water toward the switching valve 99 side.

  In the engine device 200, a circulation path 90 that returns from the vaporizer 101 to the vaporizer 101 again through the return bypass path 108, the circulation pump 109, the water-cooled exhaust manifold 6, and the feed bypass path 96 by switching the switching valves 95, 98, and 99. It is formed. The switching valves 95, 98, and 99 constitute a path switching mechanism that switches between the heating path 89 that connects the vaporizer 101 to the vaporizer water outlet 85 and the vaporizer water inlet 86 of the engine 1 and the circulation path 90.

  The switching valves 95, 98, and 99 are, for example, electromagnetic valves or motor-operated valves, and are electrically connected to a control device 110 that includes an ECU (Engine Control Unit or Electronic Control Unit). The control device 110 controls the electrical auxiliary device of the engine 1 including the switching valves 95, 98, and 99 to control the operation of the engine 1. Although details are omitted, the control device 110 includes a CPU (Central Processing Unit) that executes various arithmetic processes and controls, a ROM (Read Only Memory) in which various data are fixedly stored in advance, a control program, and various data. EEPROM (Electrically Erasable ROM) for storing rewritable data, RAM (Random Access Memory) for temporarily storing control programs and various data, a timer for time measurement, an input / output interface, and the like.

  In this embodiment, in connection with the control of the switching valves 95, 98, 99 when switching between the heating path 89 and the circulation path 90, the oil temperature sensor 111, the intake air temperature sensor 112, and the The water temperature sensor 113 is electrically connected. The oil temperature sensor 111 detects the temperature of the lubricating oil in the engine 1 and is attached to the cylinder block 5 in this embodiment. The intake air temperature sensor 112 is constituted by, for example, an intake pressure sensor (T-MAPS: Temperature-Manifold Absolute Pressure Sensor) with a temperature measurement function, and detects an intake air temperature and an intake air pressure in the intake manifold 3. The water temperature sensor 113 detects the temperature of the cooling water flowing through the engine 1, and is attached to the cooling water pump 19 in this embodiment.

  Further, the switching valves 95, 98, 99 and the circulation pump 109 are electrically connected to the output side of the control device 110. Although not shown, various sensors and the like provided in the engine 1 are electrically connected to the input side of the control device 110, and various devices and the like provided in the engine 1 are electrically connected to the output side of the control device 110. Is done.

  Next, the flow of the vaporizer freezing prevention control in the engine apparatus 200 will be described with reference to FIG. The controller 110 controls the switching valves 95, 98, 99 and the circulation pump 109 so that the cooling water circulates in the circulation path 90 when the vaporizer 101 is predicted to be frozen, for example, when the engine 1 is started at a low temperature. Control.

  When engine 1 is started (step S1: Yes), control device 110 determines whether or not the coolant temperature measured from the output of water temperature sensor 113 is lower than a predetermined water temperature threshold (step S2). . When the cooling water temperature is lower than the predetermined water temperature threshold (step S2: Yes), it is predicted that the engine 1 is cold started. At this time, control device 110 determines whether or not the intake air temperature measured from the output of intake air temperature sensor 112 is lower than a predetermined intake air temperature threshold value (step S3).

  When the intake air temperature is lower than the predetermined intake air temperature threshold (step S3: Yes), it is predicted that the ambient atmosphere of the engine device 200 is a low temperature. At this time, the control device 110 switches the switching valves 95, 98, and 99 to connect the vaporizer 101 to the circulation path 90 (step S4). In other words, the switching valve 95 connects the water outlet 84 of the exhaust manifold 6 to the feed bypass path 96 and blocks the water path between the water outlet 84 of the exhaust manifold 6 and the cooling water pump 19. The switching valve 98 connects the middle part of the water return path 94 to the return bypass path 108 and blocks the water path between the water outlet 103 of the vaporizer 101 and the vaporizer water inlet 86. Further, the switching valve 99 connects the middle part of the upstream water path 91 to the return bypass path 108 and blocks the water path between the water inlet 83 of the exhaust manifold 6 and the cylinder block 5. Thereby, the circulation path 90 is formed. The control device 110 energizes the circulation pump 109 to drive the circulation pump 109 with a desired discharge amount.

  When the circulation path 90 is formed and the circulation pump 109 is driven, the cooling water flowing out from the water outlet 103 of the vaporizer 101 to the water return path 94 is changed over to the switching valve 98, the return bypass path 108, the circulation pump 109, the switching valve 99, The refrigerant flows again into the vaporizer 101 from the water inlet 102 through the cooling water passage 82, the switching valve 95, the feed bypass passage 96 and the water feed passage 93 of the exhaust manifold 6.

  By forcibly circulating the cooling water by the circulation pump 109 in the circulation path 90, the cooling water in the exhaust manifold 6 that is likely to reach a higher temperature sooner than the cooling water in the engine 1 after the engine is started is circulated in the cooling water in the engine 1. It can be directly supplied to the vaporizer 101 without going through a route. Further, by controlling the discharge amount of the circulation pump 109, the cooling water that has passed through the cooling water passage 82 of the exhaust manifold 6 can be reliably supplied to the vaporizer 101 at a desired flow rate. Thereby, when freezing of vaporizer 101 is predicted, such as at the time of low temperature starting, freezing of vaporizer 101 can be suppressed, engine stall resulting from freezing of vaporizer 101 can be prevented, and engine startability can be improved.

  When the drive of the engine 1 is continued and the oil temperature measured from the output of the oil temperature sensor 111 exceeds a predetermined oil temperature threshold value (step S5: Yes), the control device 110 turns on the switching valves 95, 98, and 99. By switching, the coolant flow path to the vaporizer 101 is switched to the heating path 89. Further, the energization of the circulation pump 109 is cut off, and the circulation pump 109 is stopped (step S6). That is, the switching valve 95 connects the water outlet 84 of the exhaust manifold 6 to the cooling water pump 19 via the downstream water path 92. The switching valve 98 connects the water outlet 103 of the vaporizer 101 to the vaporizer water inlet 86 via a water return path 94. The switching valve 99 connects the water inlet 83 of the exhaust manifold 6 to the cooling water passage inside the cylinder block 5 via the upstream water passage 91. Thereby, the cooling water that has circulated through the engine 1 is circulated to the vaporizer 101 via the heating path 89. When the oil temperature exceeds the predetermined oil temperature threshold value, the cooling water in the engine 1 is sufficiently heated, so that the cooling water is sent from the exhaust manifold 6 and directly circulated to the vaporizer 101 via the bypass path 96. Even if it is not, freezing of the vaporizer 101 can be prevented by the cooling water flowing out from the vaporizer water outlet 86.

  Note that after the engine 1 is started (step S1: Yes), when the cooling water temperature is equal to or higher than a predetermined water temperature threshold (step S2: No), or when the intake air temperature is lower than the predetermined intake air temperature threshold (step S3). : Yes), the control device 110 controls the switching valves 95, 98, and 99 so that the cooling water flow path to the vaporizer 101 becomes the heating path 89 (step S6).

  Next, another embodiment of the engine device will be described with reference to FIGS. 8 and 9. As shown in FIG. 8, the engine device 201 of this embodiment includes an air-fuel ratio sensor 114, and the control device 110 predicts freezing of the vaporizer 101 based on the output of the air-fuel ratio sensor 114. It is different from the engine device 200. Other configurations of the engine device 201 are the same as those of the engine device 200. Although not shown in FIG. 8, the engine device 201 is provided with various sensors in addition to the air-fuel ratio sensor 114. For example, an intake air temperature sensor 112, a water temperature sensor 113 (see FIG. 6), etc. It is attached.

  The air-fuel ratio sensor 114 detects the oxygen concentration in the exhaust gas, and is attached to the exhaust gas passage 81 of the exhaust manifold 6 in this embodiment. The air-fuel ratio sensor 114 is electrically connected to the control device 110. The control device 110 measures the air-fuel ratio of the air-fuel mixture of air and fuel gas supplied to each cylinder in the cylinder block 5 from the output of the air-fuel ratio sensor 114.

  With reference to FIG. 9, the flow of the antifreezing control of the vaporizer in the engine device 201 will be described. In the engine device 201 as well, similarly to the engine device 200 of the above embodiment, the control device 110 switches the switching valve 95, so as to forcibly circulate the cooling water in the circulation path 90 when freezing of the vaporizer 101 is predicted. 98 and 99 and the circulation pump 109 are controlled.

  When engine 1 is started (step S1: Yes), control device 110 causes the air-fuel ratio of the air-fuel mixture measured from the output of air-fuel ratio sensor 114 to become leaner (lean tendency) than the predetermined air-fuel ratio threshold. It is determined whether or not there is (step S11). When the air-fuel ratio of the air-fuel mixture is larger than the predetermined air-fuel ratio threshold value (has a lean tendency), it is predicted that the vaporizer 101 tends to freeze (Step S11: Yes). That is, when the vaporizer 101 has a tendency to freeze, the liquefied fuel gas is hardly vaporized, and the freezing of the vaporizer 101 is predicted using the characteristic that the air-fuel ratio tends to be lean. Then, the control device 110 switches the switching valves 95, 98, and 99 while driving the circulation pump 109 to circulate the cooling water in the circulation path 90 (step S4). The control in step S4 in the engine device 201 is the same as the control in step S4 (see FIG. 7) in the engine device 200 of the above embodiment.

  That is, the engine device 201 forcibly circulates the cooling water at a desired flow rate by the circulation pump 109 in the circulation path 90 when the vaporizer 101 is predicted to freeze in the same manner as the engine device 200 of the above embodiment. Thus, the cooling water in the exhaust manifold 6 that is likely to reach a higher temperature faster than the cooling water in the engine 1 after the engine is started is directly supplied to the vaporizer 101. Thereby, when freezing of vaporizer 101 is predicted, such as at the time of low temperature starting, freezing of vaporizer 101 can be suppressed, engine stall resulting from freezing of vaporizer 101 can be prevented, and engine startability can be improved.

  After the engine 1 is started (step S1: Yes), when the air-fuel ratio of the air-fuel mixture is equal to or lower than the predetermined air-fuel ratio threshold value (step S11: No), the vaporizer 101 does not tend to freeze and the fuel gas vaporization is normal. It is predicted that At this time, the control device 110 controls the switching valves 95, 98, 99 and the circulation pump 109 so that the cooling water flow path to the vaporizer 101 becomes the heating path 89 (step S12).

  The control device 110 monitors the air-fuel ratio of the air-fuel mixture until the oil temperature measured from the output of the oil temperature sensor 111 exceeds a predetermined oil temperature threshold value (step S5: No, step S11). When the driving of the engine 1 is continued and the oil temperature exceeds the predetermined oil temperature threshold (step S5: Yes), the control device 110 causes the cooling water flow path to the vaporizer 101 to become the heating path 89. The switching valves 95, 98, 99 and the circulation pump 109 are controlled (step S13). When the oil temperature exceeds the predetermined oil temperature threshold value (step S5: Yes), when the circulating pump 109 is driven and the cooling water is circulated in the circulation path 90, the control device 110 is switched. The valves 95, 98, and 99 are switched to switch the coolant flow path to the vaporizer 101 to the heating path 89. Further, the control device 110 stops the circulation pump 109. The path switching control at this time is the same as the control in step S6 (see FIG. 7) in the engine device 200 of the above embodiment.

  Next, still another embodiment of the engine device will be described with reference to FIG. The engine device 202 of this embodiment further includes a switching valve 97 as compared with the engine device 200 shown in FIG. Other configurations of the engine device 202 are the same as those of the engine device 200.

  The switching valve 97 is, for example, a three-way valve, and is provided at the crossing position of the feed bypass path 96 and the water feed path 93 to switch the water inlet 102 of the vaporizer 101 to the feed bypass path 96 or the water outlet 85 for vaporizer. . In addition, the switching valve 97 is, for example, an electromagnetic valve or an electric valve, and is electrically connected to the control device 110. The switching valves 95, 97, 98, and 99 constitute a path switching mechanism that switches between the heating path 89 and the circulation path 90.

  When connecting the vaporizer 101 to the circulation path 90, the control device 110 switches to connect the water inlet 102 of the vaporizer 101 to the feed bypass path 96 in addition to the control in step S4 described with reference to FIG. The valve 97 is controlled. At this time, the switching valve 97 blocks the water path between the water inlet 102 of the vaporizer 101 and the vaporizer water outlet 85. Thereby, the circulation path 90 is configured as a closed path, and the circulation of the cooling water between the feed bypass path 96 and the vaporizer water outlet 85 is prevented. Therefore, the cooling water heated by the exhaust manifold 6 can be efficiently supplied to the vaporizer 101.

  When the vaporizer 101 is connected to the heating path 89, the controller 110 adds the water inlet 102 of the vaporizer 101 to the vaporizer water outlet 85 in addition to the control in step S6 described with reference to FIG. The switching valve 97 is controlled so as to be connected.

  Next, still another embodiment of the engine device will be described with reference to FIG. The engine device 203 of this embodiment includes opening / closing valves 115, 117, 118, and 119 in place of the switching valves 95, 97, 98, and 99, as compared with the engine device 202 shown in FIG. Other configurations of the engine device 203 are the same as those of the engine devices 200 and 202.

  The on-off valve 115 is provided in the downstream water passage 92 downstream of the branch position of the downstream water passage 92 and the feed bypass passage 96. The on-off valve 117 is provided in the water feed path 93 on the upstream side of the branch position between the water feed path 93 and the feed bypass path 96. The on-off valve 118 is provided in the water return path 94 downstream of the branch position of the water return path 94 and the return bypass path 108. The on-off valve 119 is provided in the upstream water path 91 upstream of the branch position of the upstream water path 91 and the return bypass path 108. The on-off valves 115, 117, 118, and 119 constitute a path switching mechanism that switches between the heating path 89 and the circulation path 90.

  When all the on-off valves 115, 117, 118, and 119 are in the open state, the cooling water flowing through the cooling water passage 82 of the exhaust manifold 6 passes through the water outlet 84, the downstream water passage 92, and the on-off valve 115. While flowing into the pump 19, cooling water flows from the vaporizer water outlet 85 into the water inlet 102 of the vaporizer 101 through the water feed path 93 and the on-off valve 117. On the other hand, when all of the on-off valves 115, 117, 118, and 119 are closed, the circulation path 90 is formed.

  The on-off valves 115, 117, 118, and 119 are electrically connected to the control device 110. The control device 110 switches the on-off valves 115, 117, 118, and 119 to circulate when the freezing of the vaporizer 101 is predicted in the same manner as the flow of the freeze prevention control of the vaporizer 101 described with reference to FIG. While the path 90 is formed, the circulation pump 109 is driven. As a result, when freezing of the vaporizer 101 is predicted, such as at a low temperature start, it is possible to directly supply the coolant in the exhaust manifold 6 to the vaporizer 101, which tends to reach a higher temperature sooner than the coolant in the engine 1 after the engine is started. And engine stall resulting from freezing of vaporizer 101 can be prevented, and engine startability can be improved.

  Note that the configuration further including the switching valve 97 (see FIG. 10) and the configuration including the on-off valves 115, 117, 118, and 119 (see FIG. 11) instead of the switching valves 95, 97, 98, and 99 are shown in FIG. Needless to say, the present invention is applicable to the engine apparatus 201 described with reference to FIG. Further, in the engine device 203 (see FIG. 11), the on-off valve 117 may not be provided. In this case, the circulation path 90 is formed by driving the circulation pump 109 after the on-off valves 115, 118, and 119 are closed. Further, in the engine device 200, 201, 202, a corresponding on-off valve 115, 117, 118 or 119 (see FIG. 11) is used instead of any one or more of the switching valves 95, 97, 98, 99. The structure to provide may be sufficient.

  The circulation pump 109 is provided in the return bypass path 108 in the above embodiment, but may be provided in the feed bypass path 96, for example. Further, the vaporizer water outlet 85 and the vaporizer water inlet 86 are provided in the cooling water pump 19 in the above embodiment, but are provided in other components of the engine 1 such as the cylinder head 2 and the cylinder block 5, for example. May be.

  As shown in FIGS. 1 to 6, 8, 10, and 11, the engine devices 200, 201, 202, and 203 vaporize liquefied fuel gas from the engine 1 and the gas cylinder 100 that stores liquefied fuel gas. A vaporizer 101 is provided to circulate a part of the cooling water of the engine 1 to the vaporizer 101, and includes an exhaust manifold 6 having a cooling water passage 82 for cooling the exhaust gas passage 81, and a water outlet 84 of the exhaust manifold 6. A feed bypass path 96 connected to the water inlet 102 of the vaporizer 101, a return bypass path 108 connecting the water outlet 103 of the vaporizer 101 to the water inlet 83 of the exhaust manifold 6, and a circulation pump 109 provided in the bypass path 96 or 108. A vaporizer water outlet 85 for the engine 1 and water for the vaporizer. Since there is a path switching mechanism for switching between the heating path 89 connected to the port 86 and the circulation path 90 from the vaporizer 101 through the bypass paths 96 and 108, the circulation pump 109 and the exhaust manifold 6 to return to the vaporizer 101 again. By forcibly circulating the cooling water in the circulation path 90 by the circulation pump 109, the cooling water in the exhaust manifold 6 that is likely to reach a higher temperature than the cooling water inside the engine 1 after the engine is started can be directly supplied to the vaporizer 101. Further, by controlling the discharge amount of the circulation pump 109, the cooling water that has passed through the exhaust manifold 6 can be reliably supplied to the vaporizer 101 at a desired flow rate. Thereby, when freezing of vaporizer 101 is predicted, such as at the time of low temperature starting, freezing of vaporizer 101 can be suppressed, engine stall resulting from freezing of vaporizer 101 can be prevented, and engine startability can be improved.

  As shown in FIGS. 6 and 7, when the cooling water temperature and the intake air temperature of the engine 1 are each equal to or lower than a predetermined threshold value, the engine device 200 includes switching valves 95, 98, and 99 serving as path switching mechanisms. On the other hand, the circulating pump 109 is driven to circulate the cooling water in the circulation path 90. The engine apparatus 200 can predict the freezing of the vaporizer 101 using the existing cooling water temperature sensor 113, the intake air temperature sensor 112, and the like, and it is not necessary to provide a dedicated temperature sensor or the like for the vaporizer 101. An increase in manufacturing cost of engine device 200 can be suppressed.

  As shown in FIGS. 8 and 9, the engine device 201 includes a switching valve as a path switching mechanism when the air-fuel ratio of the mixture of fuel gas and air in the engine 1 tends to be leaner than a predetermined threshold value. While 95, 98, and 99 form the circulation path 90, the circulation pump 109 is driven to circulate the cooling water in the circulation path 90. The engine device 201 can predict the freezing of the vaporizer 101 by using the characteristic that the liquefied fuel gas is less likely to be vaporized when the vaporizer 101 tends to freeze and the air-fuel ratio tends to be lean. Therefore, since the engine device 201 does not need to be provided with a dedicated temperature sensor or the like in the vaporizer 101, it is possible to reduce the manufacturing cost of the engine device 201 by using a lower cost configuration.

  The present invention is not limited to the above-described embodiment, and can be embodied in various forms. The configuration of each part is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 Engine 6 Exhaust manifold (Water-cooled exhaust manifold)
83 Water inlet (Water inlet of water-cooled exhaust manifold)
84 Water outlet (water outlet of water-cooled exhaust manifold)
85 Vaporizer water outlet 86 Vaporizer water inlet 89 Heating path 90 Circulation path 96 Feed bypass path 100 Gas cylinder (fuel gas source)
101 Vaporizer (vaporizer)
102 Water inlet (vaporizer water inlet)
103 Water outlet (vaporizer water outlet)
108 Return bypass path 109 Circulation pump 200, 201, 202, 203 Engine device

Claims (3)

In an engine device that includes an engine and a vaporizer that vaporizes a liquefied fuel gas from a fuel gas source that stores the liquefied fuel gas, and that circulates a part of the engine cooling water to the vaporizer,
A water-cooled exhaust manifold having a cooling water passage for cooling the exhaust gas passage, a feed bypass passage connecting a water outlet of the water-cooled exhaust manifold to a water inlet of the carburetor, and a water outlet of the carburetor connected to the water-cooled exhaust manifold. A return bypass path connected to the water inlet, and a circulation pump provided in the bypass path,
A heating path connecting the carburetor to a carburetor water outlet and a carburetor water inlet of the engine, and circulation returning from the carburetor to the carburetor again through the bypass path, the circulation pump, and the water-cooled exhaust manifold. An engine apparatus provided with a path switching mechanism for switching between paths.   When the engine cooling water temperature and the intake air temperature are each equal to or less than a predetermined threshold value, the path switching mechanism forms the circulation path, while the circulation pump is driven to circulate the cooling water in the circulation path. The engine device according to claim 1.   When the air-fuel ratio of the mixture of the fuel gas and air of the engine tends to be leaner than a predetermined threshold, the path switching mechanism forms the circulation path, while the circulation pump is driven to The engine device according to claim 1, wherein the cooling water is circulated in the circulation path.

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