JP2013238194A - Supercharging device of bi-fuel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily increase an output of a bi-fuel engine.SOLUTION: A supercharging device of a bi-fuel engine 10 includes a supercharger 31 using gas fuel and liquid fuel as fuel, and supercharging a large quantity of suction air to a combustion chamber of the engine 10 by driving a compressor 31A arranged in an intake passage 30 of the engine 10 by an output shaft of the engine 10 or an electric motor, performs supercharging by the compressor 31A of the supercharger 31 when using the gas fuel, and does not perform the supercharging by the compressor 31A of the supercharger 31 when using the liquid fuel.

Description

  The present invention relates to a supercharger for a bi-fuel engine.

  Conventionally, there are bi-fuel engines that use gaseous fuel such as CNG (natural gas) and liquid fuel such as gasoline as fuel.

  In a vehicle equipped with a bi-fuel engine, equipment such as a fuel cylinder, a fuel line, an injector, etc. for exclusive use of CNG are attached in addition to equipment for installing a normal gasoline engine and a diesel engine. As a result, in a vehicle equipped with a bi-fuel engine, the vehicle weight increases significantly, and the running performance (power performance) of the vehicle decreases.

  Therefore, as described in Patent Document 1, as a conventional bi-fuel engine, a turbine disposed in an exhaust passage of an engine is driven by a turbine disposed in an exhaust passage of the engine, and a large amount of intake air is introduced into a combustion chamber of the engine. Some have turbochargers that supercharge. The engine output is increased by supercharging by a turbocharger compressor to compensate for a decrease in running performance due to an increase in vehicle weight.

63-22342

  However, the conventional bi-fuel engine using a turbocharger has the following problems.

  (1) Both a gas fuel having a high octane number (for example, CNG has an octane number of 120) and a liquid fuel having a low octane number (for example, gasoline has an octane number of 90 to 100) are supercharged by a turbocharger compressor. In other words, not only when using gaseous fuel, but also when using liquid fuel, the turbocharger's compressor boost pressure corresponds to the fuel used in order to avoid inconveniences such as damage to engine parts and output reduction due to knocking. Therefore, it is necessary to control the turbocharger so that the turbocharger falls below the supercharging pressure limit value.

  (2) When the engine is cold started, the exhaust gas that has rotated the turbine of the turbocharger comes into contact with the turbine to lower the temperature, thereby delaying the temperature rise of the exhaust purification catalyst installed downstream thereof. Delaying the temperature rise of the exhaust purification catalyst causes a stagnation of its reducing ability, and deteriorates the exhaust purification performance.

An object of the present invention is to easily increase the output of a bi-fuel engine.
Another object of the present invention is to avoid delaying the temperature rise of the exhaust purification catalyst and improve the exhaust purification performance.

  The invention according to claim 1 uses gaseous fuel and liquid fuel as fuel, drives a compressor disposed in the intake passage of the engine by the output shaft of the engine or electric motor, and supplies a large amount of intake air to the combustion chamber of the engine. A supercharger for a bi-fuel engine with a supercharger that supercharges the fuel.When using gaseous fuel, the supercharger is supercharged, and when using liquid fuel, the supercharger is supercharged. This is not done.

  The invention according to claim 2 further provides an electromagnetic clutch between the output shaft of the engine or electric motor and the compressor of the supercharger in the invention according to claim 1, and connects the electromagnetic clutch when using gaseous fuel, The electromagnetic clutch is disengaged when using liquid fuel.

  According to a third aspect of the present invention, in the second aspect of the present invention, an intake bypass passage that bypasses the compressor of the supercharger and an intake bypass valve that opens and closes the intake bypass passage are provided. The valve is closed and the intake bypass valve is opened when liquid fuel is used.

  According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, an exhaust purification catalyst is provided in the exhaust passage of the engine.

  The invention according to claim 5 uses gaseous fuel and liquid fuel as fuel, and a turbine disposed in the exhaust passage of the engine drives a compressor disposed in the intake passage of the engine. A supercharger for a bi-fuel engine that has a turbocharger that supercharges intake air, which is supercharged by a turbocharger compressor when using gaseous fuel, and supercharged by a turbocharger compressor when using liquid fuel. The salary is not provided.

  The invention according to claim 6 is the invention according to claim 5, further comprising an exhaust bypass passage for bypassing the turbine of the turbocharger, an exhaust bypass valve for opening and closing the exhaust bypass passage, and a compressor for the turbocharger. An intake bypass passage that bypasses and an intake bypass valve that opens and closes the intake bypass passage are provided, and the exhaust bypass valve and the intake bypass valve are closed when using gaseous fuel, and the exhaust bypass valve and the intake bypass valve are opened when using liquid fuel. It is a thing.

(Claim 1)
(a) During normal operation of the engine (including normal cold start), a gaseous fuel having a high octane number (for example, CNG has an octane number of 120) is used. Then, the supercharging that can be supercharging pressure controlled to the high maximum supercharging pressure for the gaseous fuel, which is hard to cause such knocking, by the compressor of the supercharger driven by the output of the engine or electric motor. To implement. Accordingly, it is possible to draw out the high fuel efficiency of the engine without damaging the engine parts due to the occurrence of knocking or reducing the output, and increase the output of the engine.

  On the other hand, when using liquid fuel with a low octane number (for example, the octane number of gasoline is 90 to 100) during emergency operation of the engine (during cold start or when the gas fuel cylinder pressure drops, etc.) No supercharging with a compressor.

  The output of the bi-fuel engine is increased while simplifying that the supercharging pressure control by the supercharger is applied only to the gaseous fuel.

(Claim 2)
(b) An electromagnetic clutch is provided between the output shaft of the engine or electric motor and the compressor of the supercharger, the electromagnetic clutch is connected when using gaseous fuel, and the electromagnetic clutch is disconnected when using liquid fuel. Therefore, by performing on / off (connection / disconnection) of the electromagnetic clutch in accordance with switching between the use of gaseous fuel and liquid fuel, it is possible to easily switch between performing and not performing supercharging in the above (a).

(Claim 3)
(c) An intake bypass passage that bypasses the compressor of the supercharger and an intake bypass valve that opens and closes the intake bypass passage are provided. When the gaseous fuel is used, the intake bypass valve is closed, and when the liquid fuel is used, the intake bypass valve is opened. . Thus, when liquid fuel is used, intake air that is not supercharged by the compressor of the supercharger can be guided to the combustion chamber from the intake bypass passage that bypasses the compressor, and intake resistance by the compressor can be eliminated.

(Claim 4)
(d) When a gas fuel is used at the time of cold start of the engine and this gas fuel is supercharged by a supercharger compressor, the exhaust gas temperature is not lowered as in the case of using a turbocharger. That is, the temperature of the exhaust at the time of cold start does not appear to decrease in temperature due to contact with the turbine of the turbocharger, and as a result, the temperature of the exhaust purification catalyst on the downstream side of the exhaust is raised early by the exhaust heat. Thereby, the increase in the reduction capability of the exhaust purification catalyst can be promoted, and the exhaust purification performance can be improved.

(Claim 5)
(e) During normal operation of the engine (including normal cold start), a gaseous fuel having a high octane number (for example, CNG has an octane number of 120) is used. Then, the supercharging pressure can be controlled to a high maximum supercharging pressure for the gaseous fuel, which is difficult to cause such knocking, by a turbocharger compressor driven by the output of the engine or electric motor. To implement. Accordingly, it is possible to draw out the high fuel efficiency of the engine without damaging the engine parts due to the occurrence of knocking or reducing the output, and increase the output of the engine.

  On the other hand, when using liquid fuel with a low octane number (for example, the octane number of gasoline is 90 to 100) during emergency operation of the engine (during cold start or when the gas fuel cylinder pressure drops, etc.) No supercharging with a compressor.

  The output of the bi-fuel engine is increased while simplifying the application of the supercharging pressure control by the turbocharger only to the gaseous fuel.

(Claim 6)
(f) An exhaust bypass passage that bypasses the turbine of the turbocharger, an exhaust bypass valve that opens and closes the exhaust bypass passage, and an intake bypass passage that bypasses the compressor of the turbocharger and opens and closes the intake bypass passage An intake bypass valve is provided, and the exhaust bypass valve and the intake bypass valve are closed when gaseous fuel is used, and the exhaust bypass valve and the intake bypass valve are opened when liquid fuel is used. Therefore, by performing on / off (close / open) of the exhaust bypass valve and the intake bypass valve in accordance with the switching between the use of gaseous fuel and liquid fuel, the above-described supercharging and non-performing can be easily performed. Can be switched.

FIG. 1 is a schematic diagram illustrating a supercharger for a bi-fuel engine according to a first embodiment. FIG. 2 is a schematic diagram illustrating a supercharger for a bi-fuel engine according to a second embodiment.

Example 1 (FIG. 1)
The bi-fuel engine 10 shown in FIG. 1 uses CNG (gaseous fuel) and gasoline (liquid fuel) as fuel.

  That is, the engine 10 includes a CNG injector 11 and a gasoline injector 21. CNG filled and pressurized in the CNG cylinder 12 is sent to the CNG injector 11 through the fuel line 12 </ b> A, and injected from the CNG injector 11 into the combustion chamber of the engine 10. This fuel line 12 </ b> A is provided with a shut valve 13 that shuts off CNG and a high-pressure CNG pressure sensor 14 that measures the pressure of the CNG cylinder 12. The remaining amount of the CNG cylinder 12 is monitored by the measured pressure of the high pressure CNG pressure sensor 14. The gasoline filled in the gasoline tank 22 is sent to the gasoline injector 21 through the fuel line 22 </ b> A, and injected from the gasoline injector 21 into the combustion chamber of the engine 10.

  A compressor 31 </ b> A of a supercharger 31 is provided in the intake passage 30 for introducing combustion air into the combustion chamber of the engine 10. An air cleaner 32 and an air flow meter 33 are provided upstream of the compressor 31 </ b> A in the intake passage 30. Dust or the like in the intake air taken into the intake passage 30 is filtered by the air cleaner 32, and the amount of the intake air taken in is measured by the air flow meter 33. The compressor 31 </ b> A of the supercharger 31 compresses (supercharges) the intake air taken in via the air cleaner 32 and the air flow meter 33. The intake air that has been pressurized by the compressor 31 </ b> A to a high temperature is cooled by the intercooler 34 provided on the downstream side of the compressor 31 </ b> A and supplied to the combustion chamber of the engine 10. The intake air is supercharged by the compressor 31 </ b> A and densified by the intercooler 34, the charging efficiency of the combustion chamber of the engine 10 is improved, and a large amount is supplied to the combustion chamber of the engine 10.

  The compressor 31 </ b> A of the supercharger 31 transmits the rotational force of the drive source 35 via the electromagnetic clutch 37 via the drive transmission unit 36. The drive source 35 is an output of the engine 10. A belt as the drive transmission unit 36 is wound around a drive pulley provided on the crankshaft (output shaft) of the engine 10 and a driven pulley provided on the input shaft of the electromagnetic clutch 37. The output shaft of the electromagnetic clutch 37 is coupled to the compressor 31A. When the electromagnetic clutch 37 is connected (turned on), the compressor 31 </ b> A is driven by the output of the engine 10.

  The compressor 31A of the supercharger 31 may be driven not by the output of the engine 10 but by the output of the electric motor.

  An intake bypass passage 38 that bypasses the compressor 31A of the supercharger 31 communicates with an intermediate portion of the air flow meter 33 and the compressor 31A in the intake passage 30 and a downstream portion of the intercooler 34 (or an upstream portion of the intercooler 34). To be extended to. The intake bypass passage 38 is provided with an intake bypass valve (electromagnetic valve) 38A for opening and closing the intake bypass passage 38. The intake bypass valve 38A is opened when the supercharging pressure by the compressor 31A of the supercharger 31 is reduced or the compressor 31A is stopped.

A three-way catalyst 41 that purifies the exhaust gas is provided in the exhaust passage 40 that exhausts the exhaust gas from the combustion chamber of the engine 10. The three-way catalyst 41 oxidizes or reduces CO, HC and NOx in the exhaust to harmless CO ₂ , N ₂ and H ₂ O. An A / F sensor 42 is disposed upstream of the three-way catalyst 41 in the exhaust passage 40, and an O ₂ sensor 43 is disposed downstream. The A / F sensor 42 detects the difference in concentration between the amount of oxygen in the exhaust and the amount of oxygen in the atmosphere, and detects the air-fuel ratio (fuel / air ratio). The O ₂ sensor 43 detects the oxygen concentration in the exhaust gas. The detection results of the A / F sensor 42 and the O ₂ sensor 43 are sent to an ECU (genuine ECU 60).

The engine 10 is controlled by the CNG ECU 50 and the gasoline ECU 60.
In this embodiment, the detection signals of the A / F sensor 42 and the O ₂ sensor 43 are sent to the gasoline ECU 60 which is a genuine ECU, and the fact that the air-fuel ratio of the exhaust is controlled to a value necessary for the activation of the three-way catalyst 41 is confirmed. The gasoline ECU 60 performs A / F feedback control that detects the detection result of the A / F sensor 42 and detects that the oxidation or reduction process of the three-way catalyst 41 is appropriate based on the detection result of the O ₂ sensor 43. Do. Further, the A / F feedback control of the CNG ECU 50 is also performed using the A / F feedback control of the gasoline ECU 60.

  However, in this embodiment, the temperature of the cooling water of the engine 10 is detected by the water temperature sensor 10S provided in the engine 10. And the detection signal of the water temperature sensor 10S is sent to ECU59 for CNG and ECU60 for gasoline. The gasoline ECU 60 performs gasoline operation control using gasoline as the fuel used by the engine 10 at the time of extremely cold start (during emergency operation) where the temperature detected by the water temperature sensor 10S is extremely low. When the detected temperature of the water temperature sensor 10S is other than a very low temperature (during normal operation including normal cold start), the CNG ECU 50 performs CNG operation control in which the fuel used for the engine 10 is CNG.

  In this embodiment, the detection signal of the high pressure CNG pressure sensor 14 that measures the pressure of the CNG cylinder 12 is also sent to the CNG ECU 50 and the gasoline ECU 60. When the detected pressure of the high pressure CNG pressure sensor 14 falls below the reference value (during emergency operation), the CNG ECU 50 stops CNG operation control of the engine 10 and the gasoline ECU 60 starts gasoline operation control of the engine 10. Note that the driver can arbitrarily switch between CNG operation control of the engine 10 by the CNG ECU 50 and gasoline operation control of the engine 10 by the gasoline ECU 60.

Hereinafter, CNG operation control and gasoline operation control will be described.
(CNG operation control)
When CNG is used during normal operation of the engine 10, the engine 10 is controlled by the CNG ECU 50 based on information from each sensor and the gasoline ECU 60 as a genuine ECU. The output of the engine 10 is connected to the compressor 31A of the supercharger 31 by the electromagnetic clutch 37, and supercharging is performed by the compressor 31A. The best intake air supercharged by the compressor 31 </ b> A is supplied to the combustion chamber of the engine 10. Specifically, the air sucked from the air cleaner 32 in the intake passage 30 is measured by the air flow meter 33 and then compressed by the compressor 31A of the supercharger 31 and further cooled by the intercooler 34 and passed into the combustion chamber of the engine 10. Be paid.

  At this time, the CNG ECU 50 sets the intake bypass valve 38A provided in the intake bypass passage 38 that bypasses the compressor 31A of the supercharger 31 to be fully closed or closed. The CNG ECU 50 controls the intake pressure of the CNG by the compressor 31A by opening and closing the intake bypass valve 38A based on the output value of the boost pressure sensor 31S provided in the intake passage 30 downstream of the compressor 31A. Control within the maximum critical boost pressure range.

(Gasoline operation control)
When gasoline is used during emergency operation of the engine 10, the engine 10 is controlled by the gasoline ECU 60 based on information from each sensor. And the connection of the output of the engine 10 with respect to the compressor 31A of the supercharger 31 is interrupted by the electromagnetic clutch 37, and the supercharging by the compressor 31A is stopped. Intake air that is not supercharged by the compressor 31 </ b> A is supplied to the combustion chamber of the engine 10. Specifically, the air sucked from the air cleaner 32 in the intake passage 30 is supplied to the combustion chamber of the engine 10 after the flow rate is measured by the air flow meter 33.

  At this time, the compressor 31A of the supercharger 31 that is not driven due to the disconnection of the electromagnetic clutch 37 becomes the intake resistance, so the CNG ECU 50 is provided with an intake bypass valve provided in the intake bypass passage 38 that bypasses the compressor 31A of the supercharger 31. 38A is fully opened. The intake air that has passed through the air flow meter 33 is supplied from the intake bypass passage 38 to the combustion chamber of the engine 10.

According to the present embodiment, the following operational effects can be obtained.
(a) During normal operation of the engine 10 (including normal cold start), gaseous fuel having a high octane number (for example, CNG has an octane number of 120) is used. Then, the supercharging pressure of the gaseous fuel is controlled by the compressor 31A of the supercharger 31 driven by the output of the engine 10 or the electric motor up to a high maximum supercharging pressure for the gaseous fuel that hardly causes such knocking. Carry out supercharging. As a result, the high fuel efficiency of the engine 10 without any damage to the engine parts or the output reduction due to the occurrence of knocking can be extracted, and the output of the engine 10 can be increased.

  On the other hand, when using liquid fuel with a low octane number (for example, the octane number of gasoline is 90 to 100) during emergency operation of the engine 10 (during cold start or when the gas fuel cylinder pressure drops, etc.), the supercharger No supercharging is performed by the 31 compressor 31A.

  The output of the bi-fuel engine 10 is increased while simplifying the application of the supercharging pressure control by the supercharger 31 only to the gaseous fuel.

  (b) An electromagnetic clutch 37 is provided between the output shaft of the engine 10 or the electric motor and the compressor 31A of the supercharger 31, and the electromagnetic clutch 37 is connected when using gaseous fuel, and the electromagnetic clutch 37 is used when using liquid fuel. Cut off. Therefore, by performing on / off (connection / disconnection) of the electromagnetic clutch 37 in accordance with switching between the use of gaseous fuel and liquid fuel, it is possible to easily switch between performing and not performing the supercharging described in (a) above.

  (c) An intake bypass passage 38 that bypasses the compressor 31A of the supercharger 31 and an intake bypass valve 38A that opens and closes the intake bypass passage 38 are provided. When the gaseous fuel is used, the intake bypass valve 38A is closed to use the liquid fuel. Sometimes the intake bypass valve 38A is opened. As a result, when liquid fuel is used, intake air that is not supercharged by the compressor 31A of the supercharger 31 can be guided to the combustion chamber from the intake bypass passage 38 that bypasses the compressor 31A, and intake resistance by the compressor 31A can be eliminated.

  (d) When a gas fuel is used at the time of cold start of the engine 10 and this gas fuel is supercharged by the compressor 31A of the supercharger 31, the exhaust gas temperature is reduced as in the case of using a turbocharger. Does not occur. That is, the temperature of the exhaust at the time of cold start does not appear to drop due to contact with the turbine of the turbocharger, and as a result, the temperature of the exhaust purification catalyst 41 on the downstream side of the exhaust is raised quickly by the exhaust heat. Thereby, the increase in the reduction capability of the exhaust purification catalyst 41 can be promoted, and the exhaust purification performance can be improved.

Example 2 (FIG. 2)
The second embodiment differs from the first embodiment in that a turbocharger 44 instead of the supercharger 31 is used as a means for supercharging a large amount of intake air into the combustion chamber of the engine 10 when using CNG. In the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The turbocharger 44 includes a compressor 44 </ b> A disposed on the intake passage 30 downstream of the air flow meter 33, and a turbine 44 </ b> B disposed on the exhaust passage 40 upstream of the three-way catalyst 41. The turbocharger 44 drives the compressor 44 </ b> A by a turbine 44 </ b> B that is rotated by the exhaust pressure of the engine 10, and supercharges a large amount of intake air into the combustion chamber of the engine 10.

  The turbocharger 44 is additionally provided with an intake bypass passage 45 that bypasses the compressor 44A and an intake bypass valve 45A that opens and closes the intake bypass passage 45. The intake bypass passage 45 extends so as to communicate an intermediate portion between the air flow meter 33 and the compressor 44A in the intake passage 30 and an upstream portion of the intercooler 34 (or a downstream portion of the intercooler 34).

  The turbocharger 44 is additionally provided with an exhaust bypass passage 46 that bypasses the turbine 44B and an exhaust bypass valve 46A that opens and closes the exhaust bypass passage 46. The exhaust bypass passage 46 extends so that the upstream portion of the turbine 44B in the exhaust passage 40 and the intermediate portion between the turbine 44B and the three-way catalyst 41 communicate with each other. The intake bypass valve 45A and the exhaust bypass valve 46A are opened when the supercharging pressure by the compressor 44A of the turbocharger 44 is reduced or the compressor 44A is stopped.

  Also in this embodiment, the engine 10 is controlled by the CNG ECU 50 and the gasoline ECU 60.

That is, in this embodiment, the detection signals of the A / F sensor 42 and the O ₂ sensor 43 are sent to the gasoline ECU 60, which is a genuine ECU, and the air-fuel ratio of the exhaust is controlled to a value necessary for the activation of the three-way catalyst 41. This is detected by the detection result of the A / F sensor 42 and the A / F feedback control for detecting that the oxidation or reduction treatment of the three-way catalyst 41 is appropriate based on the detection result of the O ₂ sensor 43 is for gasoline. This is performed in the ECU 60. Further, the A / F feedback control of the CNG ECU 50 is also performed using the A / F feedback control of the gasoline ECU 60.

  However, in this embodiment, the temperature of the cooling water of the engine 10 is detected by the water temperature sensor 10S provided in the engine 10. And the detection signal of the water temperature sensor 10S is sent to ECU50 for CNG and ECU60 for gasoline. The gasoline ECU 60 performs gasoline operation control using gasoline as the fuel used by the engine 10 at the time of extremely cold start (during emergency operation) where the temperature detected by the water temperature sensor 10S is extremely low. When the detected temperature of the water temperature sensor 10S is other than a very low temperature (during normal operation including normal cold start), the CNG ECU 50 performs CNG operation control in which the fuel used for the engine 10 is CNG.

  In this embodiment, the detection signal of the high pressure CNG pressure sensor 14 that measures the pressure of the CNG cylinder 12 is also sent to the CNG ECU 50 and the gasoline ECU 60. When the detected pressure of the high pressure CNG pressure sensor 14 falls below the reference value (during emergency operation), the CNG ECU 50 stops CNG operation control of the engine 10 and the gasoline ECU 60 starts gasoline operation control of the engine 10. Note that the driver can arbitrarily switch between CNG operation control of the engine 10 by the CNG ECU 50 and gasoline operation control of the engine 10 by the gasoline ECU 60.

Hereinafter, CNG operation control and gasoline operation control will be described.
(CNG operation control)
When CNG is used during normal operation of the engine 10, the engine 10 is controlled by the CNG ECU 50 based on information from each sensor and the gasoline ECU 60 as a genuine ECU. The CNG ECU 50 rotates the turbine 44B of the turbocharger 44 by the exhaust pressure of the engine 10 and supplies a large amount of intake air supercharged by the compressor 44A driven by the turbine 44B to the combustion chamber of the engine 10. Specifically, the air taken in from the air cleaner 32 in the intake passage 30 is measured by the air flow meter 33, then compressed by the compressor 44A of the turbocharger 44, further cooled by the intercooler 34, and supplied to the combustion chamber of the engine 10. To do.

  At this time, the CNG ECU 50 is provided in the intake bypass valve 45A provided in the intake bypass passage 45 that bypasses the compressor 44A of the turbocharger 44 and in the exhaust bypass passage 46 that bypasses the turbine 44B of the turbocharger 44. Both the exhaust bypass valves 46A are set to be fully closed or closed. The CNG ECU 50 controls opening and closing of the intake bypass valve 45A and the exhaust bypass valve 46A on the basis of the output value of the boost pressure sensor 44S provided on the downstream side of the compressor 44A in the intake passage 30, thereby the CNG of the compressor 44A. The supercharging pressure is controlled within the range of the maximum critical supercharging pressure for CNG.

(Gasoline operation control)
When gasoline is used during emergency operation of the engine 10, the engine 10 is controlled by the gasoline ECU 60 based on information from each sensor. At this time, the CNG ECU 50 fully opens both the intake bypass valve 45A and the exhaust bypass valve 46A, stops the rotation of the turbine 44B of the turbocharger 44 due to the exhaust pressure of the engine 10, and stops the supercharging by the compressor 44A. Intake air that is not supercharged by the compressor 44 </ b> A is supplied to the combustion chamber of the engine 10. Specifically, the air sucked from the air cleaner 32 in the intake passage 30 is supplied to the combustion chamber of the engine 10 through the intake bypass passage 45 after the flow rate is measured by the air flow meter 33.

According to the present embodiment, the following operational effects can be obtained.
(a) During normal operation of the engine 10 (including normal cold start), gaseous fuel having a high octane number (for example, CNG has an octane number of 120) is used. The turbocharger 44A driven by the output of the engine 10 or the electric motor is subjected to supercharging pressure control up to the high maximum supercharging pressure for gaseous fuel that is unlikely to cause such knocking. Carry out supercharging. As a result, the high fuel efficiency of the engine 10 without any damage to the engine parts or the output reduction due to the occurrence of knocking can be extracted, and the output of the engine 10 can be increased.

  On the other hand, when using the liquid fuel with a low octane number (for example, the octane number of gasoline is 90 to 100) during emergency operation of the engine 10 (during cold start or when the gas fuel cylinder pressure drops, etc.), the turbocharger No supercharging is performed by the 44 compressor 44A.

  The output of the bi-fuel engine 10 is increased while simplifying the application of the supercharging pressure control by the turbocharger 44 only to the gaseous fuel.

  (b) an exhaust bypass passage 46 that bypasses the turbine 44B of the turbocharger 44, an exhaust bypass valve 46A that opens and closes the exhaust bypass passage 46, and an intake bypass passage 45 that bypasses the compressor 44A of the turbocharger 44; An intake bypass valve 45A for opening and closing the intake bypass passage 45 is provided, and the exhaust bypass valve 46A and the intake bypass valve 45A are closed when the gaseous fuel is used, and the exhaust bypass valve 46A and the intake bypass valve 45A are opened when the liquid fuel is used. Accordingly, by turning on / off (closing / opening) the exhaust bypass valve 46A and the intake bypass valve 45A in accordance with switching between the use of gaseous fuel and liquid fuel, the supercharging in (a) is performed or not performed. Easy switching.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the gaseous fuel is not limited to CNG, and the liquid fuel is not limited to gasoline.

  The present invention uses gaseous fuel and liquid fuel as fuel, drives a compressor disposed in the intake passage of the engine by the output shaft of the engine or electric motor, and supercharges a large amount of intake air into the combustion chamber of the engine. A supercharger for a bi-fuel engine having a supercharger, which performs supercharging with a supercharger compressor when using gaseous fuel, and does not perform supercharging with a supercharger compressor when using liquid fuel. Thereby, the output of a bi-fuel engine can be increased easily.

  In the present invention, an exhaust purification catalyst is provided in the exhaust passage of the engine. As a result, it is possible to avoid a delay in the temperature rise of the exhaust purification catalyst and improve the exhaust purification performance.

  Further, the present invention uses gaseous fuel and liquid fuel as fuel, and a turbine disposed in the exhaust passage of the engine drives a compressor disposed in the intake passage of the engine so that a large amount of intake air is introduced into the engine combustion chamber. This is a supercharger for a bi-fuel engine that has a turbocharger that supercharges the turbocharger.When using gaseous fuel, it is supercharged by the turbocharger compressor, and when using liquid fuel, it is supercharged by the turbocharger compressor. Don't do it. Thereby, the output of a bi-fuel engine can be increased easily.

DESCRIPTION OF SYMBOLS 10 Bi-fuel engine 30 Intake passage 31 Supercharger 31A Compressor 37 Electromagnetic clutch 38 Intake bypass passage 38A Intake bypass valve 40 Exhaust passage 41 Three-way catalyst (exhaust purification catalyst)
44 Turbocharger 44A Compressor 44B Turbine 45 Intake bypass passage 45A Intake bypass valve 46 Exhaust bypass passage 46A Exhaust bypass valve 50 ECU for CNG
60 ECU for gasoline

Claims (6)

Use gaseous fuel and liquid fuel as fuel,
A supercharger for a bi-fuel engine having a supercharger that drives a compressor disposed in an intake passage of an engine by an output shaft of an engine or an electric motor and supercharges a large amount of intake air into a combustion chamber of the engine. There,
A supercharger for a bi-fuel engine that performs supercharging with a supercharger compressor when using gaseous fuel and does not perform supercharging with a supercharger compressor when using liquid fuel. An electromagnetic clutch is provided between the output shaft of the engine or electric motor and the compressor of the supercharger,
The supercharger for a bi-fuel engine according to claim 1, wherein an electromagnetic clutch is connected when gaseous fuel is used, and the electromagnetic clutch is disconnected when liquid fuel is used. An intake bypass passage that bypasses the compressor of the supercharger and an intake bypass valve that opens and closes the intake bypass passage;
The supercharger for a bi-fuel engine according to claim 2, wherein the intake bypass valve is closed when gaseous fuel is used, and the intake bypass valve is opened when liquid fuel is used.   The supercharger for a bi-fuel engine according to any one of claims 1 to 3, wherein an exhaust purification catalyst is provided in the exhaust passage of the engine. Use gaseous fuel and liquid fuel as fuel,
Supercharging of a bi-fuel engine having a turbocharger that drives a compressor disposed in the intake passage of the engine by a turbine disposed in the exhaust passage of the engine and supercharges a large amount of intake air into the combustion chamber of the engine A device,
A supercharger for a bi-fuel engine that performs supercharging with a turbocharger compressor when using gaseous fuel and does not perform supercharging with a turbocharger compressor when using liquid fuel. An exhaust bypass passage that bypasses the turbine of the turbocharger and an exhaust bypass valve that opens and closes the exhaust bypass passage are provided.
An intake bypass passage that bypasses the compressor of the turbocharger and an intake bypass valve that opens and closes the intake bypass passage are provided.
The supercharger for a bi-fuel engine according to claim 5, wherein the exhaust bypass valve and the intake bypass valve are closed when the gaseous fuel is used, and the exhaust bypass valve and the intake bypass valve are opened when the liquid fuel is used.

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