JP6907691B2 - Intake and exhaust structure of compressed natural gas engine - Google Patents

Description

The present invention relates to an intake / exhaust structure of a compressed natural gas engine.

Compressed natural gas vehicles use a three-way catalyst to purify nitrogen oxides, hydrocarbons, and carbon monoxide in the exhaust gas (see, for example, Patent Document 1).

JP-A-2017-002865

It is necessary to operate a compressed natural gas engine in the stoichiometric combustion operating region in order to purify nitrogen oxides, hydrocarbons and carbon monoxide in the exhaust using a three-way catalyst.

However, if the compressed natural gas engine is operated in the stoichiometric combustion operation region, the fuel efficiency deteriorates and the exhaust temperature becomes high, which may adversely affect the durability of the compressed natural gas engine.

Especially in the high load operation region, it is necessary to lower the exhaust temperature by using exhaust gas recirculation without using fuel enrichment that accompanies deterioration of fuel efficiency, but in compressed natural gas vehicles equipped with a supercharger. The exhaust pressure tends to be lower than the intake pressure, and it is difficult to increase the exhaust gas recirculation rate.

Also, unlike a diesel engine, a compressed natural gas engine needs to supply a large amount of air to the cylinder together with fuel in order to obtain a predetermined torque, so a compressed natural gas vehicle equipped with a supercharger has a small capacity. Transient responsiveness (starting responsiveness) is improved by using the prime mover of.

However, if a small-capacity prime mover equipped with a turbocharger is used, it will not be optimal in the entire area and a considerable loss will occur, and the exhaust pressure will be high in the high-speed, high-load operation area, so the exhaust temperature will rise. There is a risk of rising.

Therefore, the present invention has an intake / exhaust structure of a compressed natural gas engine that suppresses an increase in the exhaust temperature and does not adversely affect the durability of the compressed natural gas engine while reducing the loss of the turbocharger and reducing the deterioration of fuel efficiency. The purpose is to provide.

The present invention includes a turbocharger compressor installed in an intake passage, a first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake air on the intake upstream side of the compressor. A detour intake passage that communicates the passage with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. The prime mover of the machine, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and the intake passage. The exhaust gas recirculation pipe connected to the intake downstream end of the exhaust passage, the exhaust gas pipe connected to the exhaust upstream end of the exhaust passage, the exhaust gas recirculation passage connecting the exhaust gas pipe to the intake gas pipe, and the exhaust gas recirculation. comprising an exhaust recirculation valve which is installed in the circulation passage, and a control device for opening and closing said exhaust gas recirculation valve wherein the first diaphragm valves and said second diaphragm valves and the waste gate valve, the control device In the low rotation and low load operation region, the first throttle valve and the second throttle valve are opened and the exhaust relief valve and the exhaust gas recirculation valve are closed, so that the supercharging pressure rises. Provided is an intake / exhaust structure of a compressed natural gas engine that closes the second throttle valve.

Further, the compressor of the supercharger installed in the intake passage, the first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake passage on the intake upstream side of the compressor. A detour intake passage communicating with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. A prime mover, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and intake of the intake passage. An exhaust gas recirculation pipe connected to a downstream end, an exhaust gas recirculation pipe connected to an exhaust upstream end of the exhaust passage, an exhaust recirculation passage connecting the exhaust gas pipe to the intake gas pipe, and an exhaust gas recirculation passage. The exhaust gas recirculation valve is provided with a control device for opening and closing the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust recirculation valve. In the low rotation and high load operation region, the intake / exhaust structure of the compressed natural gas engine that opens the first throttle valve and the exhaust gas recirculation valve and closes the second throttle valve and the exhaust relief valve is provided. offer.

Further, the compressor of the supercharger installed in the intake passage, the first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake passage on the intake upstream side of the compressor. A detour intake passage communicating with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. A prime mover, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and intake of the intake passage. An intake gas recirculation pipe connected to the downstream end, an exhaust gas recirculation pipe connected to the exhaust upstream end of the exhaust passage, an exhaust gas recirculation passage connecting the exhaust gas pipe to the intake gas recirculation pipe, and an exhaust gas recirculation passage. The exhaust gas recirculation valve is provided with a control device for opening and closing the first air throttle valve, the second air throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve. Provided is an intake / exhaust structure of a compressed natural gas engine that opens the first throttle valve, the second throttle valve, and the exhaust gas recirculation valve and closes the exhaust relief valve in the medium-high rotation low load operation region. do.

Further, the compressor of the supercharger installed in the intake passage, the first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake passage on the intake upstream side of the compressor. A detour intake passage communicating with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. A prime mover, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and intake of the intake passage. An intake gas recirculation pipe connected to the downstream end, an exhaust gas recirculation pipe connected to the exhaust upstream end of the exhaust passage, an exhaust gas recirculation passage connecting the exhaust gas pipe to the intake gas recirculation pipe, and an exhaust gas recirculation passage. The exhaust gas recirculation valve is provided with a control device for opening and closing the first air throttle valve, the second air throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve. Provided is an intake / exhaust structure of a compressed natural gas engine that opens the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve in the low-medium-high rotation medium-load operation region. ..

Further, the compressor of the supercharger installed in the intake passage, the first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake passage on the intake upstream side of the compressor. A detour intake passage communicating with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. A prime mover, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and intake of the intake passage. An exhaust gas recirculation pipe connected to a downstream end, an exhaust gas recirculation pipe connected to an exhaust upstream end of the exhaust passage, an exhaust recirculation passage connecting the exhaust gas pipe to the intake gas pipe, and an exhaust gas recirculation passage. The exhaust gas recirculation valve is provided with a control device for opening and closing the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust recirculation valve. In the medium-high rotation high load operation region, the first throttle valve, the second throttle valve, and the exhaust gas recirculation valve are opened and the exhaust gas recirculation valve is closed, and the intake pressure is adjusted to the accelerator opening and the engine rotation. Provided is an intake / exhaust structure of a compressed natural gas engine that opens the exhaust relief valve in order to bring the intake pressure to the target intake pressure when the target intake pressure corresponding to the number cannot be reached.

Further, the compressor of the supercharger installed in the intake passage, the first throttle valve installed in the intake passage on the intake downstream side of the compressor, and the intake passage on the intake upstream side of the compressor. A detour intake passage communicating with the intake passage between the compressor and the first throttle valve, a second throttle valve installed in the detour intake passage, and a supercharger installed in the exhaust passage. A prime mover, a detour exhaust passage that connects the exhaust passage on the exhaust upstream side of the prime mover to the exhaust passage on the exhaust downstream side of the prime mover, an exhaust relief valve installed in the detour exhaust passage, and intake of the intake passage. An exhaust gas recirculation pipe connected to a downstream end, an exhaust gas recirculation pipe connected to an exhaust upstream end of the exhaust passage, an exhaust recirculation passage connecting the exhaust gas pipe to the intake gas pipe, and an exhaust gas recirculation passage. The exhaust gas recirculation valve is provided with a control device for opening and closing the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust recirculation valve. In the medium-high rotation high-load operation region at low and high temperatures, the suction of the compressed natural gas engine that opens the first throttle valve, the second throttle valve, and the exhaust gas recirculation valve and closes the exhaust gas recirculation valve. Provides an exhaust structure.

It is desirable that the exhaust braking valve provided in the exhaust passage on the downstream side of the exhaust of the prime mover is further provided, and the control device also opens and closes the exhaust braking valve.

It is desirable that the control device opens the first throttle valve and the second throttle valve and closes the exhaust braking valve in the exhaust braking operation operation region.

INDUSTRIAL APPLICABILITY The present invention provides an intake / exhaust structure of a compressed natural gas engine that suppresses an increase in exhaust temperature and does not adversely affect the durability of the compressed natural gas engine while reducing the loss of the turbocharger and improving fuel efficiency. You can do things.

It is a figure explaining the intake / exhaust structure of the compressed natural gas engine which concerns on embodiment of this invention. It is a figure explaining the input / output relation of a control device. It is a figure explaining the operation area. It is a figure explaining the operation of the intake / exhaust structure in a low rotation low load operation region. It is the figure which summarized the control and the movement of a compressed natural gas engine in a low rotation low load operation region. It is a figure explaining the operation of the intake / exhaust structure in a low rotation high load operation region. It is the figure which summarized the control and the movement of a compressed natural gas engine in a low rotation high load operation region. It is a figure explaining the operation of the intake / exhaust structure in a medium-high rotation low load operation region. It is the figure which summarized the control and the movement of a compressed natural gas engine in a medium-high rotation low-load operation region. It is a figure explaining the operation of the intake / exhaust structure in a low medium high rotation medium load operation region. It is the figure which summarized the control and the movement of the compressed natural gas engine in the low medium high rotation medium load operation region. It is a figure explaining the operation of the intake / exhaust structure in a medium-high rotation high load operation region. It is the figure which summarized the control and the movement of the compressed natural gas engine in the medium-high rotation high load operation region. It is a figure explaining the operation of the intake / exhaust structure in a medium-high rotation high load operation region at a low high temperature. It is the figure which summarized the control and the movement of a compressed natural gas engine in a medium-high rotation high-load operation region at a low high temperature. It is a figure explaining the operation of the intake / exhaust structure in the exhaust braking operation operation area. It is the figure which summarized the control and the movement of the compressed natural gas engine in the exhaust braking operation operation area.

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

As shown in FIGS. 1 and 2, the intake / exhaust structure 100 of the compressed natural gas engine according to the embodiment of the present invention includes an intake passage 101, an exhaust passage 102, an intake multi-tube 103, and an exhaust multi-tube 104. The compressor 106 of the supercharger 105, the prime mover 107 of the supercharger 105, the first throttle valve 108, the detour intake passage 109, the second throttle valve 110, the detour exhaust passage 111, and the exhaust relief valve. The exhaust gas recirculation passage 113, the exhaust gas recirculation valve 114, the exhaust braking valve 115, and the control device 116 are provided.

The intake passage 101 is a so-called intake pipe, and supplies intake air to each of the plurality of cylinders 117. The exhaust passage 102 is a so-called exhaust pipe, and exhausts exhaust gas from each of the plurality of cylinders 117. The intake passage 101 and the exhaust passage 102 are arranged along various routes according to the vehicle type.

The intake multi-purpose pipe 103 is connected to the intake downstream end of the intake passage 101 and divides the intake air supplied to the compressed natural gas engine through the intake passage 101 into each of the plurality of cylinders 117. The exhaust multi-purpose pipe 104 is connected to the exhaust upstream end of the exhaust passage 102 and joins the exhaust discharged from each of the plurality of cylinders 117 into the exhaust passage 102.

The first pressure detector 118 is installed in the intake multi-tube 103. The first pressure detector 118 is a so-called MAP sensor, which is connected to the control device 116 and detects the absolute pressure of the intake multi-tube 103. In the present specification, the absolute pressure of the intake multi-tube 103 detected by the first pressure detector 118 is defined as "intake multi-tube pressure".

The supercharger 105 includes a compressor 106, a prime mover 107, and a rotating shaft 119. The supercharger 105 is a so-called exhaust turbine type supercharger, and a large amount is driven by using the kinetic energy of the exhaust to drive the prime mover 107 and using the kinetic energy of the prime mover 107 to drive the compressor 106. Air is compressed (supercharged) and supplied to each of a plurality of cylinders 117. The compressor 106 is a so-called compressor and is installed in the intake passage 101. The prime mover 107 is a so-called turbine and is installed in the exhaust passage 102. The rotating shaft 119 rotatably connects the compressor 106 and the prime mover 107 coaxially.

The three-way catalyst 120 is installed in the exhaust passage 102 on the downstream side of the exhaust of the prime mover 107. The three-way catalyst 120 purifies nitrogen oxides, hydrocarbons, and carbon monoxide in the exhaust gas.

The first throttle valve 108 is installed in the intake passage 101 on the downstream side of the intake of the compressor 106, and increases or decreases the amount of intake air supplied to the intake multi-tube 103 through the intake passage 101 according to the opening degree.

The intercooler 121 is installed in the intake passage 101 between the compressor 106 and the first throttle valve 108. The intercooler 121 is a so-called heat exchanger, and cools the air compressed and heated by the supercharger 105.

A second pressure detector 122 is installed in the intake passage 101 between the first throttle valve 108 and the intercooler 121. The second pressure detector 122 is a so-called MAP sensor, which is connected to the control device 116 and detects the absolute pressure of the intake passage 101 between the first throttle valve 108 and the intercooler 121. In the present specification, the absolute pressure of the intake passage 101 between the first throttle valve 108 and the intercooler 121 detected by the second pressure detector 122 is defined as "intake passage pressure".

The detour intake passage 109 is a so-called detour intake pipe, and the intake passage 101 on the intake upstream side of the compressor 106 is placed between the compressor 106 and the first throttle valve 108, specifically, the intercooler 121. It communicates with the intake passage 101 between the first throttle valve 108 and divides the intake air supplied to the intake multi-tube 103 through the intake passage 101 into two paths.

The second throttle valve 110 is installed in the detour intake passage 109 and increases or decreases the amount of intake air supplied to the intake multi-purpose pipe 103 through the detour intake passage 109 according to the opening degree. As a result, the second throttle valve 110 increases or decreases the amount of intake air supplied to the compressor 106 through the intake passage 101 according to the opening degree.

The detour exhaust passage 111 is a so-called detour exhaust pipe, and communicates the exhaust passage 102 on the exhaust upstream side of the prime mover 107 to the exhaust passage 102 on the exhaust downstream side of the prime mover 107 and exhausts two exhaust gases discharged through the exhaust passage 102. Divide into the route.

The exhaust relief valve 112 is installed in the bypass exhaust passage 111 and increases or decreases the amount of exhaust gas discharged through the bypass exhaust passage 111 according to the opening degree. As a result, the exhaust relief valve 112 increases or decreases the amount of exhaust gas supplied to the prime mover 107 through the exhaust passage 102 according to the opening degree.

The exhaust gas recirculation passage 113 is a so-called exhaust gas recirculation pipe, which communicates the exhaust gas recirculation pipe 104 with the intake gas recirculation pipe 103 and circulates a part of the exhaust gas to the intake air. An exhaust gas recirculation cooler 123 is installed in the exhaust gas recirculation passage 113. The exhaust gas recirculation cooler 123 is a so-called heat exchanger, and cools the exhaust gas recirculated to the intake air through the exhaust gas recirculation passage 113.

The exhaust gas recirculation valve 114 is installed in the exhaust recirculation passage 113 on the downstream side of the recirculation of the exhaust recirculation cooler 123, and increases or decreases the amount of exhaust gas recirculated to the intake air through the exhaust recirculation passage 113 according to the opening degree.

The exhaust braking valve 115 is installed in the exhaust passage 102 on the downstream side of the exhaust of the prime mover 107, and shuts off the exhaust gas discharged through the exhaust passage 102 when the exhaust brake is operated to increase the braking force.

The control device 116 is a so-called engine control unit, and opens and closes the first throttle valve 108, the second throttle valve 110, the exhaust relief valve 112, the exhaust recirculation valve 114, and the exhaust braking valve 115.

The accelerator opening degree and the engine speed are input to the control device 116. The accelerator opening degree is detected by the accelerator opening degree sensor 124. The engine speed is detected by the engine speed sensor 125.

In the present specification, an operating region having a low engine speed is defined as a "low rotation operating region", and an operating region having a high engine speed is defined as a "high rotation operating region". The operating region between the "low rotation operating region" and the "high rotation operating region" is defined as the "medium rotation operating region".

Similarly, an operating region with a low engine load is defined as a "low load operating region", and an operating region with a high engine load is defined as a "high load operating region". The operating area between the "low load operating area" and the "high load operating area" is defined as the "medium load operating area".

Since the boundary that divides each operating area changes according to the engine performance, the boundary that divides each operating area is not specified in this specification.

[Operation of intake / exhaust structure 100 in low rotation and low load operation region]
As shown in FIG. 3, in the low rotation low load operation region A, the control device 116 opens the first throttle valve 108 and the second throttle valve 110 as shown in FIGS. 4 and 5. The exhaust relief valve 112 and the exhaust gas recirculation valve 114 are closed, and the second throttle valve 110 is closed as the supercharging pressure rises. The exhaust braking valve 115 is naturally closed.

Specifically, when the driver depresses the accelerator slightly, the control device 116 reduces the first throttle valve 108 so that the intake multi-tube pressure detected by the first pressure detector 118 matches the target intake multi-tube pressure. open.

The target intake multi-purpose pipe pressure can be set according to the accelerator opening degree detected by the accelerator opening degree sensor 124 and the engine rotation speed detected by the engine rotation speed sensor 125.

When the first throttle valve 108 is opened small, only a small amount of intake air is supplied to each of the plurality of cylinders 117 and is burned as a mixture with fuel in each of the plurality of cylinders 117.

The control device 116 has a fuel injection pulse width and ignition timing according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. And is set and fuel is injected by the injector according to the set pulse width and ignited by the spark plug according to the set ignition timing.

However, since the load is low and the exhaust gas does not have sufficient kinetic energy to drive the prime mover 107, the compressor 106 may cause an intake throttle loss.

In the intake / exhaust structure 100, the control device 116 detours by opening the second throttle valve 110 according to the accelerator opening detected by the accelerator opening sensor 124 and the engine speed detected by the engine speed sensor 125. The intake air can be supplied to each of the plurality of cylinders 117 while bypassing the compressor 106 through the intake passage 109.

Since it is possible to suppress the compressor 106 from causing a throttle loss of the intake air, it is possible to quickly start the torque and give the exhaust enough kinetic energy to drive the prime mover 107.

Further, since the compressor 106 is bypassed through the detour intake passage 109 to supply intake air to each of the plurality of cylinders 117, the compressor 106 is unlikely to be a drive resistance to the prime mover 107, and the prime mover 107 (and thus the compressor 106). ) Is easy to increase, and the boost pressure is also easy to increase.

Further, since the exhaust relief valve 112 and the exhaust gas recirculation valve 114 are closed, the exhaust loss is small, the exhaust pressure is easily increased, and the boost pressure is also easily increased.

Further, since the second throttle valve 110 is closed as the boost pressure rises, the transient responsiveness (starting responsiveness) can be improved without using a small-capacity prime mover 107.

Therefore, in the intake / exhaust structure 100, the torque can be quickly increased while suppressing the deterioration of fuel efficiency.

[Operation of intake / exhaust structure 100 in low rotation and high load operation region]
As shown in FIG. 3, in the low rotation and high load operation region B, as shown in FIGS. 6 and 7, the control device 116 opens the first throttle valve 108 and the exhaust recirculation valve 114, and at the same time, the first throttle valve 108 and the exhaust gas recirculation valve 114 are opened. (Ii) Close the throttle valve 110 and the exhaust relief valve 112.

Specifically, when the driver depresses the accelerator significantly, the control device 116 completes the first throttle valve 108 so that the intake multi-tube pressure detected by the first pressure detector 118 matches the target intake multi-tube pressure. Open to. Further, the control device 116 completely closes the second throttle valve 110 in order to increase the torque together with the boost pressure.

When the first throttle valve 108 is completely opened and the second throttle valve 110 is completely closed, the first throttle valve 108 does not cause a throttle loss of the intake air, the compressor 106 is driven, and a large amount of intake air is generated. Since it is supplied to each of the cylinders 117 and burned as an air-fuel mixture with the fuel in each of the plurality of cylinders 117, the rotation speed of the prime mover 107 (and thus the compressor 106) is increased and the supercharging pressure is also increased. Will be done.

The control device 116 has a fuel injection pulse width and ignition timing according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. And is set and fuel is injected according to the set pulse width and ignited according to the set ignition timing.

At the same time, the control device 116 closes the exhaust relief valve 112, so that the difference between the intake pressure and the exhaust pressure becomes smaller due to the increase in the exhaust pressure, and the calculation is based on the intake multi-tube pressure detected by the first pressure detector 118. Exhaust gas recirculation can be applied to the extent that knocking can be prevented by opening the exhaust gas recirculation valve 114 by the control device 116 according to the intake amount and the engine speed detected by the engine rotation speed sensor 125.

When the exhaust gas recirculation is applied, the knocking control device does not make a knocking determination, so that the ignition timing is not delayed and the ignition timing can be set to the optimum value. Furthermore, the exhaust temperature can be lowered by applying exhaust gas recirculation.

Therefore, in the intake / exhaust structure 100, there is no intake throttle loss, and the ignition timing can be set to the optimum value, so that the fuel consumption can be improved.

[Operation of intake / exhaust structure 100 in medium / high rotation / low load operation region]
As shown in FIG. 3, in the medium-high rotation low load operation region (and a part of the low rotation low load operation region) C, the control device 116 is the first throttle valve as shown in FIGS. 8 and 9. The 108, the second throttle valve 110, and the exhaust gas recirculation valve 114 are opened, and the exhaust relief valve 112 is closed.

Specifically, when the driver depresses the accelerator slightly, the control device 116 reduces the first throttle valve 108 so that the intake multi-tube pressure detected by the first pressure detector 118 matches the target intake multi-tube pressure. open.

When the first throttle valve 108 is opened small, only a small amount of intake air is supplied to each of the plurality of cylinders 117 and is burned as a mixture with fuel in each of the plurality of cylinders 117.

The control device 116 has a fuel injection pulse width and ignition timing according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. And is set and fuel is injected according to the set pulse width and ignited according to the set ignition timing.

However, since the load is low and the exhaust gas does not have sufficient kinetic energy to drive the prime mover 107, the compressor 106 may cause an intake throttle loss.

In the intake / exhaust structure 100, the control device 116 detours by opening the second throttle valve 110 according to the accelerator opening detected by the accelerator opening sensor 124 and the engine speed detected by the engine speed sensor 125. The intake air can be supplied to each of the plurality of cylinders 117 while bypassing the compressor 106 through the intake passage 109.

Since it is possible to suppress the compressor 106 from causing a throttle loss of the intake air, it is possible to quickly start the torque and give the exhaust enough kinetic energy to drive the prime mover 107.

Further, since the compressor 106 is bypassed through the detour intake passage 109 to supply intake air to each of the plurality of cylinders 117, the compressor 106 is unlikely to be a drive resistance to the prime mover 107, and the prime mover 107 (and thus the compressor 106). ) Is easy to increase, and the boost pressure is also easy to increase.

At the same time, the control device 116 opens the exhaust gas recirculation valve 114 according to the intake amount calculated based on the intake multi-pipe pressure detected by the first pressure detector 118 and the engine rotation speed detected by the engine rotation speed sensor 125. Since the opening degree of the one throttle valve 108 is small and the intake pressure is low, the difference between the intake pressure and the exhaust pressure is large, and a large amount of exhaust gas recirculation is applied. By applying a large amount of exhaust gas recirculation, pumping loss can be reduced and fuel efficiency can be improved.

Further, since the exhaust relief valve 112 is closed, the exhaust loss is small, the exhaust pressure is easily increased, and the boost pressure is also easily increased.

Therefore, in the intake / exhaust structure 100, the torque can be quickly increased while suppressing the deterioration of fuel efficiency.

[Operation of intake / exhaust structure 100 in low-medium-high-speed medium-load operation region]
As shown in FIG. 3, in the low-medium-high rotation medium-load operating region D, the control device 116 includes the first throttle valve 108, the second throttle valve 110, and the exhaust relief as shown in FIGS. 10 and 11. The valve 112 and the exhaust gas recirculation valve 114 are opened.

Specifically, when the driver depresses the accelerator to a medium level (accelerator opening of about 50%), the control device is designed to match the intake multi-tube pressure detected by the first pressure detector 118 with the target intake multi-tube pressure. 116 opens the first throttle valve 108 to a medium degree (opening of about 50%).

Further, in order to obtain the acceleration force, the control device 116 opens the second throttle valve 110 small according to the accelerator opening degree detected by the accelerator opening degree sensor 124 and the engine rotation speed detected by the engine rotation speed sensor 125.

When the first throttle valve 108 is opened moderately and the second throttle valve 110 is opened small, the compressor 106 is driven and intake air is supplied to each of the plurality of cylinders 117 and at each of the plurality of cylinders 117. Since it is burned as an air-fuel mixture with fuel, the rotation speed of the prime mover 107 (and thus the compressor 106) is increased, and the supercharging pressure is also increased.

The control device 116 has a fuel injection pulse width and ignition timing according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. And is set and fuel is injected according to the set pulse width and ignited according to the set ignition timing.

At the same time, the control device 116 opens the exhaust gas recirculation valve 114 according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. Further, the exhaust relief valve 112 is opened according to the accelerator opening degree detected by the accelerator opening degree sensor 124.

Exhaust gas recirculation is applied as the exhaust pressure rises, and even if the first throttle valve 108 is closed, the intake multi-pipe pressure becomes close to the positive pressure and the pumping loss becomes smaller, so fuel efficiency can be improved. ..

Further, the control device 116 sets the intake multi-tube pressure detected by the first pressure detector 118 and the intake passage pressure detected by the second pressure detector 122 in order to open the first throttle valve 108 as much as possible (completely). The opening degree of the second throttle valve 110 is adjusted so as to match.

That is, when the intake amount sent by the compressor 106 exceeds the required intake amount of the compressed natural gas engine, the first throttle valve 108 is closed, so that the intake throttle loss occurs, but the intake throttle loss is minimized. The opening degree of the second throttle valve 110 is adjusted so that the intake multi-tube pressure detected by the first pressure detector 118 and the intake passage pressure detected by the second pressure detector 122 are matched so as to eliminate the boost pressure. The resistance of the compressor 106 due to the excessive rise of the compressor 106 is reduced.

Therefore, in the intake / exhaust structure 100, the first throttle valve 108 that controls the torque is unlikely to cause a throttle loss of the intake air, and the fuel consumption can be improved.

[Operation of intake / exhaust structure 100 in medium-high rotation and high-load operation region]
As shown in FIG. 3, in the medium-high rotation high load operation region E, the control device 116 includes the first throttle valve 108, the second throttle valve 110, and the exhaust gas recirculation as shown in FIGS. 12 and 13. The valve 114 is opened and the exhaust relief valve 112 is closed, and the accelerator opening sensor 124 detects the intake pressure (intake multi-tube pressure detected by the first pressure detector 118) and the engine rotation speed sensor 125 detects it. When it is not possible to reach the target intake pressure according to the engine rotation speed, the exhaust relief valve 112 is opened so that the intake pressure reaches the target intake pressure.

Specifically, when the driver depresses the accelerator greatly (accelerator opening 70% or more), the control device 116 is designed to match the intake multi-tube pressure detected by the first pressure detector 118 with the target intake multi-tube pressure. Fully opens the first throttle valve 108.

Further, in order to obtain the acceleration force, the control device 116 opens the second throttle valve 110 small according to the accelerator opening degree detected by the accelerator opening degree sensor 124 and the engine rotation speed detected by the engine rotation speed sensor 125.

When the first throttle valve 108 is completely opened and the second throttle valve 110 is opened slightly, the compressor 106 is driven and intake air is supplied to each of the plurality of cylinders 117 and in each of the plurality of cylinders 117. Since it is burned as an air-fuel mixture with fuel, the rotation speed of the prime mover 107 (and thus the compressor 106) is increased, and the supercharging pressure is also increased. Further, the control device 116 closes the exhaust relief valve 112 to increase the exhaust pressure.

The control device 116 has a fuel injection pulse width and ignition timing according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. And is set and fuel is injected according to the set pulse width and ignited according to the set ignition timing.

At the same time, the control device 116 knocks by opening the exhaust gas recirculation valve 114 according to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine speed detected by the engine speed sensor 125. Exhaust gas recirculation can be applied to the extent that this can be prevented.

When the exhaust gas recirculation is applied, the knocking control device does not make a knocking determination and does not retard. In addition, since the exhaust gas recirculation is applied and the combustion speed is slowed down, the advance angle can be achieved, and the exhaust temperature does not rise even if the fuel is not enriched. That is, fuel consumption can be suppressed.

If the torque increases too much by completely opening the first throttle valve 108, the second throttle valve 110 is opened to release the pressure. Further, if the target torque is not reached even if the second throttle valve 110 is completely closed, the boost pressure is adjusted by adjusting the opening degree of the exhaust relief valve 112.

As described above, the exhaust temperature becomes high in the medium-high rotation and high-load operation region, and it is necessary to increase the exhaust gas recirculation rate in order to lower the exhaust temperature. Since the exhaust gas recirculation is applied due to the difference between the exhaust gas and the exhaust gas recirculation, the exhaust gas recirculation is increased by closing the exhaust relief valve 112.

However, since the kinetic energy of the exhaust gas increases as the engine speed increases, the amount of intake air sent by the compressor 106 also increases when the kinetic energy of the exhaust gas is large, and the intake multi-pipe pressure rises, resulting in exhaust gas recirculation. Since it becomes difficult to apply the pressure, the optimum state can be obtained by opening the second throttle valve 110 and releasing the pressure.

[Operation of intake / exhaust structure 100 in medium-high rotation high-load operation region at low and high temperatures]
In the medium-high rotation high-load operation region at low and high temperatures, the control device 116 opens the first throttle valve 108, the second throttle valve 110, and the exhaust relief valve 112, as shown in FIGS. 14 and 15. At the same time, the exhaust gas recirculation valve 114 is closed.

Specifically, when the temperature of the cooling water is low or abnormally high, the exhaust gas recirculation device is likely to break down, so that the exhaust gas recirculation control is stopped and the exhaust gas recirculation valve 114 is completely closed. Therefore, when the driver depresses the accelerator greatly (accelerator opening 70% or more), the control device 116 first throttles the intake multi-tube pressure detected by the first pressure detector 118 to match the target intake multi-tube pressure. The air valve 108 is fully opened.

Further, in order to obtain the acceleration force, the intake multi-tube pressure detected by the first pressure detector 118 is determined according to the accelerator opening detected by the accelerator opening sensor 124 and the engine rotation speed detected by the engine rotation speed sensor 125. The control device 116 opens the second throttle valve 110 small in order to match the target intake multi-tube pressure for when the exhaust gas recirculation is stopped.

Further, when the intake multi-pipe pressure detected by the first pressure detector 118 does not reach the target intake multi-tube pressure for when the exhaust gas recirculation is stopped, the opening degree of the second throttle valve 110 is adjusted.

When the first throttle valve 108 is completely opened and the second throttle valve 110 is opened slightly, the compressor 106 is driven and intake air is supplied to each of the plurality of cylinders 117 and in each of the plurality of cylinders 117. Since it is burned as an air-fuel mixture with fuel, the rotation speed of the prime mover 107 (and thus the compressor 106) is increased, and the supercharging pressure is also increased.

When the exhaust gas recirculation of the fuel injection is stopped, the control device 116 corresponds to the intake amount calculated based on the intake multi-tube pressure detected by the first pressure detector 118 and the engine rotation speed detected by the engine rotation speed sensor 125. Set the pulse width and the ignition timing for exhaust gas recirculation stop, and inject fuel according to the set pulse width for exhaust gas recirculation stop and ignite according to the set ignition timing for exhaust gas recirculation stop. At this time, knocking does not occur because the boost pressure is lowered and the retarded ignition timing is used.

Since exhaust gas recirculation is not applied and torque is excessive even if the exhaust relief valve 112 is completely opened, pressure is applied so that the second throttle valve 110 is opened and the first throttle valve 108 does not cause intake throttle loss. Let go. At this time, since there is no exhaust gas recirculation, retarding is performed to avoid knocking. The amount of fuel is increased and the exhaust temperature is lowered so that the exhaust temperature does not rise too much due to the timing retard.

As described above, the exhaust gas recirculation cannot be applied due to the influence of coagulated water at low water temperature and the reliability problem of the exhaust gas recirculation cooler 123 at high water temperature. If the exhaust gas recirculation cannot be used, the output can be obtained with a small amount of intake air, so the amount of intake air is reduced by opening the exhaust relief valve 112 and the second throttle valve 110.

[Operation of intake / exhaust structure 100 in the exhaust braking operation operation region]
As shown in FIG. 3, in the exhaust braking operation operation region F, the control device 116 opens the first throttle valve 108 and the second throttle valve 110 and exhausts as shown in FIGS. 16 and 17. Close the braking valve 115.

Specifically, when the driver turns on the exhaust braking switch and releases the accelerator, the control device 116 cuts the fuel and matches the intake multi-tube pressure detected by the first pressure detector 118 with the target intake multi-tube pressure. Opens the first throttle valve 108 small and sends a small amount of intake air.

Further, the accelerator opening degree and the engine speed sensor 125 detected by the accelerator opening degree sensor 124 are detected in order to raise the exhaust pressure by closing the exhaust braking valve 115 by the control device 116 and bypass the non-rotating compressor 106. The control device 116 opens the second throttle valve 110 according to the engine speed. As described above, the air is compressed and the braking force is improved. When the temperature drops and the pressure drops, the braking force drops, so the first throttle valve 108 is opened while observing the pressure.

When the exhaust braking is no longer necessary, the exhaust braking valve 115 is opened to return to normal control. That is, when the engine speed becomes less than the fuel return speed, the exhaust braking valve 115 is opened and fuel injection is restarted.

As described above, when the exhaust braking is activated, the compressor 106 causes a throttle loss of the intake air, and the intake air does not enter and the exhaust braking force becomes small. However, in the intake / exhaust structure 100, the second throttle valve 110 is opened. By doing so, it is possible to send in intake air and increase the exhaust braking force.

As described above, according to the present invention, while reducing the loss of the turbocharger and reducing the deterioration of fuel consumption, the compressed natural gas that suppresses the rise in the exhaust temperature and does not easily adversely affect the durability of the compressed natural gas engine. An engine intake / exhaust structure 100 can be provided.

100 Intake / exhaust structure 101 Intake passage 102 Exhaust passage 103 Intake multi-pipe 104 Exhaust multi-tube 105 Supercharger 106 Compressor 107 Motor 108 First throttle valve 109 Bypass intake passage 110 Second throttle valve 111 Bypass exhaust passage 112 Exhaust escape Valve 113 Exhaust gas recirculation passage 114 Exhaust gas recirculation valve 115 Exhaust braking valve 116 Control device 117 Cylinder 118 First pressure detector 119 Rotating shaft 120 Three-way catalyst 121 Intercooler 122 Second pressure detector 123 Exhaust recirculation cooler 124 Accelerator opening Sensor 125 Engine rotation speed sensor A Low rotation low load operation area B Low rotation high load operation area C Medium high rotation Low load operation area D Low medium high rotation Medium load operation area E Medium high rotation High load operation area F Exhaust braking operation operation area

Claims (8)

The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
Equipped with a,
In the low rotation and low load operation region, the control device opens the first throttle valve and the second throttle valve, closes the exhaust relief valve and the exhaust recirculation valve, and boosts the pressure. An intake / exhaust structure of a compressed natural gas engine characterized in that the second throttle valve is closed as the temperature rises. The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
With
The control device opens the first throttle valve and the exhaust gas recirculation valve and closes the second throttle valve and the exhaust relief valve in the low rotation and high load operation region.
The intake and exhaust structure of a compressed natural gas engine that is characterized by this. The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
With
The control device opens the first throttle valve, the second throttle valve, and the exhaust gas recirculation valve and closes the exhaust relief valve in the medium-high rotation low load operation region.
The intake and exhaust structure of a compressed natural gas engine that is characterized by this. The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
With
The control device opens the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust recirculation valve in the low-medium-high rotation medium-load operation region.
The intake and exhaust structure of a compressed natural gas engine that is characterized by this. The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
With
In the medium-high rotation and high-load operation region, the control device opens the first throttle valve, the second throttle valve, and the exhaust recirculation valve, closes the exhaust relief valve, and accelerates the intake pressure. When the target intake pressure according to the opening degree and the engine rotation speed cannot be reached, the exhaust relief valve is opened to bring the intake pressure to the target intake pressure.
The intake and exhaust structure of a compressed natural gas engine that is characterized by this. The compressor of the supercharger installed in the intake passage and
A first throttle valve installed in the intake passage on the downstream side of the intake of the compressor,
A detour intake passage that communicates the intake passage on the intake upstream side of the compressor with the intake passage between the compressor and the first throttle valve.
The second throttle valve installed in the detour intake passage and
The prime mover of the turbocharger installed in the exhaust passage and
A detour exhaust passage that communicates the exhaust passage on the exhaust upstream side of the prime mover with the exhaust passage on the exhaust downstream side of the prime mover.
The exhaust relief valve installed in the detour exhaust passage and
An intake multi-tube connected to the intake downstream end of the intake passage,
Exhaust multi-purpose pipe connected to the exhaust upstream end of the exhaust passage,
An exhaust gas recirculation passage that communicates the exhaust gas recirculation pipe with the intake air pipe,
The exhaust recirculation valve installed in the exhaust recirculation passage and
A control device that opens and closes the first throttle valve, the second throttle valve, the exhaust relief valve, and the exhaust gas recirculation valve.
With
The control device opens the first throttle valve, the second throttle valve, and the exhaust relief valve and closes the exhaust recirculation valve in the medium-high rotation high load operation region at low and high temperatures.
The intake and exhaust structure of a compressed natural gas engine that is characterized by this. Further provided with an exhaust braking valve installed in the exhaust passage on the downstream side of the exhaust of the prime mover.
The intake / exhaust structure of a compressed natural gas engine according to any one of claims 1 to 6 , wherein the control device also opens and closes the exhaust braking valve. The suction of the compressed natural gas engine according to claim 7 , wherein the control device opens the first throttle valve and the second throttle valve and closes the exhaust braking valve in the exhaust braking operation operating region. Exhaust structure.

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