CN105264198A - Engine system, and ship - Google Patents

Abstract

The engine system (100) reduces the opening area of the variable nozzle (32) when the amount of exhaust gas discharged from the engine body (10) decreases, thereby increasing the volume of the exhaust gas supplied to the supercharger (20). The ratio of the amount to the amount of exhaust gas discharged from the engine body (10), and when the amount of exhaust gas discharged from the engine body (10) increases, the opening area of the variable nozzle (32) is increased, thereby, The ratio of the amount of exhaust gas supplied to the supercharger (20) relative to the amount of exhaust gas discharged from the engine body (10) is reduced.

Description

Engine systems and ships

technical field

The present invention relates to engine systems that efficiently recover waste heat energy.

Background technique

In an engine system including both a supercharger and a power turbine driven by exhaust energy (for example, refer to Patent Document 1), a required amount of exhaust gas is preferentially supplied to the supercharger side and the remaining exhaust gas is supplied to the supercharger side. to the control of the power turbine side.

Also, in an engine system including both a supercharger and a power turbine, there are cases where control is performed by providing an on-off valve in the flow path of the exhaust gas supplied to the power turbine side, and closing the valve according to operating conditions. Open and close the valve to prevent exhaust gas from flowing into the power turbine side.

Prior art literature:

Patent documents:

Patent Document 1: Japanese Patent Application Laid-Open No. 10-169455.

Contents of the invention

Problems to be solved by the invention:

In an engine system that performs control such as preferentially supplying exhaust gas to the supercharger side, the power turbine is most affected by changes in the amount of exhaust gas discharged from the engine body, and the setting of the power turbine becomes a problem. For example, it is reasonable to set the power turbine at high efficiency during normal operation of the main body of the engine, but in this case, if more exhaust than normal operation is supplied, part of the exhaust is discarded to Avoid power turbine speed exceeding allowable value. Such use does not necessarily fully recover waste heat energy. In addition, the simplification of the system is naturally required for the engine system.

Also, as for the control not to let the exhaust gas flow into the power turbine side, even if the on-off valve is closed to prevent the exhaust gas from flowing into the power turbine, when the power turbine is connected to the engine body, the power turbine is still driven by the engine body. At this time, the power turbine operates like a blower to try to deliver gas, but the on-off valve is closed so that the gas does not flow. Therefore, a large force is required to drive the power turbine, resulting in a large load on the engine body.

The present invention was made in view of such circumstances, and an object of the present invention is to provide an engine system capable of efficiently recovering waste heat energy and achieving simplification of the system.

Also, an object of the present invention is to suppress excessive load on the engine main body when the power turbine is not driven by exhaust gas.

Means to solve the problem:

An engine system according to an aspect of the present invention includes: an engine main body; a supercharger driven by exhaust gas discharged from the engine main body; a power turbine driven by exhaust gas discharged from the engine main body; The exhaust gas discharged from the engine body is introduced into the supercharger inlet pipe of the supercharger; and the exhaust gas discharged from the exhaust engine body is introduced into the power turbine inlet pipe of the power turbine; the power turbine has a a variable nozzle on the inlet side; and formed into a structure that performs exhaust flow control that reduces the opening of the variable nozzle when the amount of exhaust gas discharged from the engine main body decreases area, thereby increasing the ratio of the amount of exhaust gas supplied to the supercharger to the amount of exhaust gas discharged from the engine body, and when the amount of exhaust gas discharged from the engine body increases , increasing an opening area of the variable nozzle, thereby reducing a ratio of an amount of exhaust gas supplied to the supercharger to an amount of exhaust gas discharged from the engine main body.

Typically, a variable nozzle is used to change its opening area to improve the efficiency of the turbine (power turbine in the above structure) according to the exhaust volume. According to the above configuration, by changing the opening area of the variable nozzle, the amount of exhaust gas supplied to the supercharger can also be adjusted at the same time. That is, according to the above-mentioned configuration, both control of efficiently recovering waste heat energy according to the exhaust gas amount and control of supplying an appropriate amount of exhaust gas to the supercharger can be performed by the variable nozzle. Therefore, according to the above-mentioned engine system, waste heat energy can be recovered efficiently and the system can be simplified.

In the above engine system, the power turbine inlet pipe may be formed to branch from the supercharger inlet pipe, and part of the exhaust gas in the supercharger inlet pipe may be introduced into the power turbine. structure.

Also, in the above engine system, the engine main body may have a scavenging pipe for containing fresh air boosted by the supercharger; when the pressure in the scavenging pipe is lower than a prescribed lower limit, the The opening degree of the variable nozzle is controlled, and the opening degree of the variable nozzle is increased when the pressure in the scavenging pipe is greater than a predetermined upper limit value, so as to control the exhaust flow rate. According to the above configuration, since the variable nozzle is opened and closed based on the pressure in the scavenging pipe, it is possible to more reliably and easily supply an appropriate amount of exhaust gas to the supercharger.

In addition, in the above engine system, the predetermined lower limit value and the predetermined upper limit value may be set to increase as the load on the engine main body increases. According to the above configuration, the upper limit value and the lower limit value of the pressure in the scavenging pipe can be appropriately set according to the engine load.

Furthermore, an engine system according to another aspect of the present invention includes: an engine main body; a supercharger driven by exhaust gas discharged from the engine main body; a supercharger driven by exhaust gas discharged from the engine main body; The power turbine connected to the crankshaft of the engine body; the exhaust gas discharged from the engine body is introduced into the supercharger inlet pipe of the supercharger; the exhaust gas discharged from the engine body is introduced into the power turbine the power turbine inlet pipe; the on-off valve that is installed in the power turbine inlet pipe and is opened and closed according to the operating conditions of the engine body; and the power turbine inlet pipe that is closer to the downstream side than the on-off valve an air extraction pipe that is partially connected and extracts gas from the power turbine inlet pipe; and an air extraction valve provided on the air extraction pipe; When the load is greater than the first condition of the specified switching load, the on-off valve is opened and the air extraction valve is closed; when the engine body is reversed or the load of the engine body is In the second condition, the on-off valve is closed or set to a smaller opening than that of the on-off valve in the first condition, and the air extraction valve is opened.

According to the above configuration, when the power turbine is not driven by the exhaust gas, even if the power turbine is driven by the crankshaft of the engine body, the gas that has passed through the power turbine is sucked from the suction pipe, so it is possible to suppress excessive generation of exhaust gas to the engine body that drives the power turbine. load.

In addition, in the above engine system, the power turbine inlet pipe may be formed to branch from the supercharger inlet pipe, and part of the exhaust gas in the supercharger inlet pipe may be introduced into the power turbine inlet pipe. Turbine structure.

In addition, in the above-mentioned engine system, the switching load when the load on the engine main body increases, that is, the up switching load may be set to be lower than the switching load when the load on the engine main body decreases, that is, the down switching load. The load is heavy. According to the above configuration, it is possible to operate the engine system in consideration of the different characteristics when the load on the engine main body rises and when it falls. Therefore, more suitable operation of the engine system can be realized.

In addition, the engine system may be configured to close the exhaust valve and then open the on-off valve when the load on the engine body increases to exceed the increase switching load. According to the above-mentioned structure, the on-off valve is opened after closing the exhaust valve instead of opening the on-off valve at the same time as the exhaust valve is closed, so that the flow path with low resistance is not formed for a moment, and the supercharger can be stably exhaust supply.

Furthermore, the engine system may be configured to close the on-off valve and then open the exhaust valve when the load on the engine main body drops below the drop switching load. In this case, too, a flow path with low resistance is not formed for a moment, and the exhaust gas can be stably supplied to the supercharger.

In addition, the above-mentioned engine system may further include a power turbine outlet pipe that discharges exhaust gas that has passed through the power turbine; the suction pipe is connected to the power turbine outlet pipe, The gas extracted from the piping is discharged to the power turbine outlet piping. According to the above configuration, even if the power turbine is driven by the crankshaft of the engine body when the power turbine is not driven by the exhaust gas, the gas passing through the power turbine circulates in the circulation flow path including the suction pipe, so excessive generation of exhaust gas on the engine body can be suppressed. load.

In addition, the above-mentioned engine system may further include: the outlet pipe of the power turbine is connected between the portion connected to the suction pipe and the power turbine, and the external air can be introduced into the power turbine. an air introduction pipe of the outlet pipe; and an air introduction valve provided on the air introduction pipe; and a structure formed in which the air introduction valve is closed under the first condition and the air introduction valve is opened under the second condition. Introduce the valve. According to the above structure, since the gas in the circulation flow path is replaced, it is possible to suppress an excessive increase in the temperature of the gas in the circulation flow path.

In addition, in the above-mentioned engine system, a supercharger outlet pipe for discharging exhaust gas passing through the supercharger may be further provided; the suction pipe is connected to the supercharger outlet pipe, The gas extracted from the inlet pipe of the power turbine is discharged to the outlet pipe of the supercharger. According to the above structure, since the above-mentioned circulation flow path is not formed at all, the temperature of the gas in the circulation flow path does not rise excessively.

Furthermore, a ship according to an aspect of the present invention includes any one of the above-mentioned engine systems.

Invention effect:

As described above, according to the engine system of the above one aspect, waste heat energy can be recovered efficiently and the system can be simplified.

Also, according to another aspect of the engine system, when the power turbine is not driven by the exhaust gas, it is possible to suppress excessive load on the engine main body.

Description of drawings

FIG. 1 is an overall view of an engine system according to a first embodiment;

FIG. 2 is a block diagram of a control system of the above-mentioned engine system;

FIG. 3 is a flowchart showing control contents of the above-mentioned engine system;

Figure 4 is a graph showing the range of suitable scavenging air pressures;

5 is an overall view of an engine system according to a second embodiment;

Fig. 6 is an overall view of an engine system according to a third embodiment.

detailed description

Hereinafter, an engine system according to an embodiment will be described with reference to the drawings. Hereinafter, the same reference numerals are assigned to the same or corresponding elements throughout the drawings, and repeated descriptions will be omitted.

(first embodiment)

＜The overall structure of the engine system＞

First, the overall configuration of the engine system 100 according to the first embodiment will be described. FIG. 1 is an overall view of an engine system 100 according to the present embodiment. As shown in FIG. 1 , an engine system 100 according to this embodiment is a so-called main engine for navigating a ship 101, and includes an engine main body 10, a supercharger 20, a power turbine 30, various piping 41 to 45, and various valves. 51, 52. Hereinafter, this will be described in order.

The engine body 10 is a central device of the engine system 100 . The engine main body 10 of this embodiment is a so-called low-speed diesel engine. The engine main body 10 rotates the propeller shaft 103 on which the propeller 102 is attached at the tip, and can perform forward rotation for generating propulsion force in a direction to advance the ship 101 and reverse rotation for generation of propulsion force in a direction for the ship 101 to retreat. The propeller shaft 103 is connected to the crankshaft 11 , and the crankshaft 11 is connected to the plurality of pistons 12 . Each piston 12 reciprocates within the cylinder 13 as the fuel explodes, and the crankshaft 11 is rotated by the reciprocation of each piston 12 . In addition, an engine tachometer 14 for measuring the rotational speed of the crankshaft 11 , that is, the rotational speed of the engine main body 10 is provided in the engine main body 10 .

Furthermore, the engine main body 10 includes a common scavenging pipe 15 located on the upstream side of each cylinder 13 and a common exhaust pipe 16 located on the downstream side of each cylinder 13 . The scavenging pipe 15 temporarily stores the air compressed by the supercharger 20 and supplies it to each cylinder 13 . A scavenging air gauge 17 for measuring the pressure in the scavenging air pipe 15 (hereinafter referred to as “scavenging air pressure”) is provided in the scavenging air pipe 15 . The exhaust pipe 16 temporarily stores the exhaust gas discharged from the cylinder 13 and supplies it to the supercharger 20 and the power turbine 30 . The engine main body 10 includes a scavenging pipe 15 and an exhaust pipe 16 so that pulsation caused by the combustion cycle of each cylinder 13 can be suppressed. In addition, as the load on the engine body 10 (hereinafter referred to as “engine load”) increases, the amount of exhaust gas discharged from the engine body 10 also increases.

The supercharger 20 is a device that compresses air introduced from the outside and supplies it to the engine main body 10 . The supercharger 20 has a turbine unit 21 and a compressor unit 22 . Exhaust gas discharged from the engine body 10 (exhaust pipe 16 ) is supplied to the turbine unit 21 . The turbine unit 21 is rotated by energy of exhaust gas supplied from the exhaust pipe 16 . The exhaust gas passing through the turbine unit 21 is introduced into the flue through the supercharger outlet pipe 46 . The compressor unit 22 is connected to the turbine unit 21 through a connecting shaft 23 . Therefore, as the turbine section 21 rotates, the compressor section 22 also rotates. The compressor part 22 compresses the air introduced from the outside, and supplies it to the scavenging air pipe 15 . In addition, when the engine load is small, the amount of exhaust gas discharged from the engine body 10 is smaller than the amount required by the supercharger 20, but as the engine load increases, the amount of exhaust gas discharged from the engine body 10 gradually increases and exceeds The amount required for the supercharger 20.

The power turbine 30 is a device that assists the operation of the engine main body 10 by using exhaust energy. The power turbine 30 has a turbine section 31 and a variable nozzle 32 . When the exhaust gas is supplied to the power turbine 30 , the turbine unit 31 is rotated by the energy of the supplied exhaust gas. The turbine unit 31 is connected to the crankshaft 11 of the engine body 10 through a speed reducer 33 , and the rotational power of the turbine unit 21 is transmitted to the crankshaft 11 through the speed reducer 33 . In addition, the rotation direction of the power turbine 30 when rotating by the exhaust gas remains constant, and the operation of the engine body 10 can be assisted only when the engine body 10 is rotating forward.

The variable nozzle 32 is provided on the inlet side of the power turbine 30 and is mainly composed of a plurality of movable blades arranged in an annular shape. By changing the angle of the movable vane, the opening area (opening degree) of the movable nozzle 32 can be adjusted. By adjusting the opening degree of the variable nozzle 32, the inflow speed to the turbine part 21 is changed, and the power turbine 30 is efficiently operated. That is, when the flow rate of the exhaust gas supplied to the power turbine 30 is large, the opening degree of the variable nozzle 32 is increased, and when the flow rate of the exhaust gas supplied to the power turbine 30 is small, the opening degree of the variable nozzle 32 is decreased. . On the other hand, since the opening area of the variable nozzle 32 can be changed, it also functions as a "throttling part". The function of the variable nozzle 32 as a throttle is very important in this embodiment. That is, in the present embodiment, the opening degree of the variable nozzle 32 is adjusted to not only efficiently rotate the power turbine 30 (turbine portion 31 ), but also to control the amount of exhaust gas supplied to the supercharger 20 (supplied to The ratio of the amount of exhaust gas from the supercharger 20 to the amount of exhaust gas discharged from the engine main body 10) (exhaust gas flow rate control).

The engine system 100 according to this embodiment includes a supercharger inlet pipe 41 , a power turbine inlet pipe 42 , a power turbine outlet pipe 43 , an air extraction pipe 44 , and an engine inlet pipe 45 . Among them, the supercharger inlet pipe 41 is a pipe that connects the exhaust pipe 16 and the turbine portion 21 of the supercharger 20 and introduces exhaust gas discharged from the engine main body 10 into the supercharger 20 . Moreover, the turbine inlet pipe 42 is a pipe that branches off from the supercharger inlet pipe 41 and extends toward the power turbine 30 , and introduces part of the exhaust gas in the supercharger inlet pipe 41 to the power turbine 30 . Moreover, the power turbine output pipe 43 is a pipe which is arranged on the downstream side of the power turbine 30 and introduces the exhaust gas passing through the power turbine 30 into the flue. In addition, the suction pipe 44 is a pipe that connects a portion of the power turbine inlet pipe 42 on the downstream side of an on-off valve 51 described below to the power turbine outlet pipe 43 . Also, the engine inlet pipe 45 is a pipe that connects the compressor unit 22 of the supercharger 20 and the scavenging pipe 15 , and introduces the air compressed by the supercharger 20 into the scavenging pipe 15 .

The on-off valve 51 is a valve provided in the power turbine inlet pipe 42 . The on-off valve 51 is closed when the engine main body 10 reverses (when the ship 101 goes astern) and when the engine load is small. When the engine body 10 reverses, the power turbine 30 and the engine body 10 (crankshaft 11 ) rotate in opposite directions, so the on-off valve 51 is closed to stop exhaust gas from flowing into the power turbine 30 , thereby preventing the power turbine 30 from driving. Also, when the engine load is small, the amount of exhaust gas discharged from the engine body 10 is small, so unless all the exhaust gas is supplied to the supercharger 20, the temperature of the combustion chamber components of the engine body 10 rises. Therefore, when the engine load is small, all the exhaust gas discharged from the engine main body 10 is supplied to the supercharger 20 by closing the on-off valve 51 . In addition, the on-off valve 51 of the present embodiment may be a valve capable of maintaining two states of "open" and "closed", but may be a valve whose opening degree can be adjusted.

The exhaust valve 52 is a valve provided on the exhaust piping 44 . When the on-off valve 51 is closed, the power turbine 30 is not driven by exhaust gas, but the power turbine 30 is connected to the crankshaft 11, so the power turbine 30 is driven by the crankshaft 11 (engine body 10) while the engine body 10 is rotating. . At this time, the power turbine 30 functions as a blower. In the present embodiment, when the on-off valve 51 is closed, the purge valve 52 is opened to form a circulation flow path through which gas circulates through the power turbine 30 (circulation flow path formation control). That is, when the on-off valve 51 is closed, the exhaust valve 52 is opened, so that the gas flows into the power turbine outlet pipe 43, the power turbine 30, and the power turbine inlet pipe sequentially no matter when the engine body 10 is rotating forward or reversely. 42. Air extraction pipe 44 and power turbine outlet pipe 43 form a counterclockwise circulation flow path in FIG. 1 .

Assuming that the air extraction pipe 44 and the air extraction valve 52 are not provided, and the circulation flow path cannot be formed when the on-off valve 51 is closed, the following problems arise in this case. The power turbine 30 tries to send the gas in the power turbine outlet pipe 43 into the power turbine inlet pipe 42 regardless of whether the engine body 10 is rotating forward or reverse. However, when the on-off valve 51 is closed, the pressure in the power turbine inlet pipe 42 gradually rises, and the pressure difference across the power turbine 30 increases. As a result, driving the power turbine 30 imposes a large load on the engine main body 10 . Therefore, in this embodiment, the circulation flow path is formed when the on-off valve 51 is closed, thereby avoiding the above-mentioned problems. In addition, in the case of the present embodiment, the exhaust valve 52 may be a valve capable of maintaining two states of "open" and "closed", but may be a valve whose opening degree can be adjusted.

Next, the setting of the engine system 100 will be described. As described above, when the on-off valve 51 is opened, the amount of exhaust gas supplied to the supercharger 20 is adjusted by the opening degree of the variable nozzle 32 . Here, the opening degree of the variable nozzle 32 for supplying an appropriate amount of exhaust gas to the supercharger 20 is referred to as "an appropriate amount supply opening degree". At this time, a predetermined amount of exhaust gas is supplied to the power turbine 30, and the opening degree of the variable nozzle 32 that enables the power turbine 30 to rotate at the highest efficiency when the exhaust gas flow into the power turbine 30 is called "maximum efficiency." opening". Thus, in the engine system 100 according to the present embodiment, the "proper amount supply opening" and the "maximum efficiency opening" are set to be approximately the same (for example, within 5%) under any engine load. That is, the engine system 100 is set so that the power turbine 30 must be efficiently rotated as long as the opening degree of the variable nozzle 32 is adjusted and an appropriate amount of exhaust gas is supplied to the supercharger 20 under any engine load. In addition, it can be performed by changing the combination of the turbine blades of the turbine part 31 of the power turbine 30 and the variable nozzle 32, or by changing the turbine nozzles, turbine blades, compressor impellers, compressor diffusers, etc. of the supercharger 20. above settings.

<Structure of control system>

Next, the configuration of the control system in the engine system 100 will be described. The engine system 100 includes a control device 60 that controls the entire engine system 100 . The control device 60 is constituted by CPU, ROM, RAM, and the like. FIG. 2 is a block diagram of a control system of the engine system 100 . As shown in FIG. 2, the control device 60 is connected with the steering operation panel 104 for operating the ship 101, the engine tachometer 14 for measuring the rotational speed of the engine main body 10, the fuel input amount indicator 18 for measuring the input amount of fuel into the cylinder 13, and the measurement unit. The scavenging pressure gauge 17 of the scavenging pressure is electrically connected. The control device 60 acquires various information such as the rotation direction of the engine main body 10, the engine speed, the fuel input amount, and the scavenging pressure based on input signals from these various devices.

In addition, the control device 60 executes various calculations and the like based on input signals from the various devices described above, and controls each unit of the engine system 100 . In the present embodiment, the control device 60 is electrically connected to the on-off valve 51, the air extraction valve 52, and the variable nozzle 32, and based on the results of calculations performed based on the respective input signals, 52 and the variable nozzle 32 send control signals.

In addition, a valve control unit 61 and a variable nozzle control unit 62 are provided as functional structures of the control device 60 . Among them, the valve control unit 61 is a part that controls the opening and closing of the on-off valve 51 and the purge valve 52 , and executes circulation channel formation control described later. On the other hand, the variable nozzle control part 62 is a part which determines the opening degree of the variable nozzle 32, and performs the exhaust flow rate control mentioned later. Hereinafter, the circulation flow path formation control and the exhaust gas flow rate control performed by the control device 60 will be described in order.

＜Circulation channel formation control＞

First, the circulation channel formation control will be described with reference to FIG. 3 . FIG. 3 is a flowchart showing control contents of the engine system 100 . While the engine system 100 is operating, the control device 60 repeats the loop of steps S1 to S16 in FIG. 3 . Steps S1 to S10 in FIG. 3 are related to the control of the circulation channel formation. As outlined above, the circulation flow path formation control is the control of opening the purge valve 52 when the on-off valve 51 is closed to form a circulation flow path of the gas passing through the power turbine 30 .

First, the control device 60 acquires various information (step S1). Specifically, the control device 60 acquires the rotation direction of the engine main body, the engine speed, the fuel input amount, and the scavenging air pressure based on input signals from each device.

Next, the control device 60 determines whether or not the engine main body 10 is rotating forward (step S2 ). When the engine main body 10 rotates forward ("Yes" in step S2), it proceeds to step S3, and when the engine main body 10 rotates backward ("No" in step S2), it proceeds to step S4. However, in step S4, the purge valve 52 is opened while the on-off valve 51 is closed, and the process returns to step S1. The purpose of closing the on-off valve 51 when the engine main body 10 reverses in this way is to avoid mutual cancellation of power between the power turbine 30 and the crankshaft 11 . In addition, opening the purge valve 52 when the on-off valve 51 is closed is for the purpose of reducing the load on the engine by forming a circulation flow path through which the gas passing through the power turbine 30 circulates as described above.

In step S3, it is determined whether the on-off valve 51 is currently closed and the exhaust valve 52 is open. That is, in step S3 , it is determined (confirmed) how the on-off valve 51 and the purge valve 52 were opened and closed in the previous cycle. In addition, at least at the time of determination in step S3, if the on-off valve 51 is opened, the exhaust valve 52 must be closed, and when the on-off valve 51 is closed, the exhaust valve 52 must be opened. When it is determined that the on-off valve 51 is closed and the exhaust valve 52 is open (YES in step S3 ), the control device 60 proceeds to step S5 . Also, when it is determined that the on-off valve 51 is open and the exhaust valve 52 is closed (NO in step S3 ), the process proceeds to step S6 .

In step S5, the engine load is calculated based on the rotation speed of the engine main body 10 and the fuel injection amount, and it is determined whether or not the engine load is equal to or greater than the rise switching load. If it is determined in step S3 that the on-off valve 51 is closed, the process proceeds to step S5 , so it can be considered that the control to close the on-off valve 51 was executed at least in the previous cycle. The on-off valve 51 is closed because the engine load is small and exhaust gas cannot be supplied to the power turbine 30 . Therefore, in step S5 , it is determined whether the engine load is so small that the exhaust gas cannot be supplied to the power turbine 30 , or whether the engine load has increased to such an extent that the exhaust gas can be supplied to the power turbine 30 . That is, the "up switching load" in step S5 refers to the engine load when the engine load is increased and exhaust gas can be supplied to the power turbine 30, and is set to 50% load in this embodiment, for example (when the 50% load when the maximum load is set to 100%).

In step S5, when the engine load is equal to or higher than the rising switching load ("Yes" in step S5), the exhaust gas can be supplied to the power turbine 30, so the on-off valve 51 is opened, and the extraction valve 52 is closed (step S7 ). However, in this embodiment, instead of closing the on-off valve 51 and opening the exhaust valve 52 at the same time, the on-off valve 51 is opened after a certain period of time after the exhaust valve 52 is closed. Assuming that the purge valve 52 is closed while the on-off valve 51 is opened, a state in which both the on-off valve 51 and the purge valve 52 are opened temporarily occurs, thereby causing the gas in the power turbine inlet pipe 42 to pass through without passing through the power turbine 30 . The bypass flow path where the suction pipe 44 discharges to the power turbine outlet pipe 43 . The flow path resistance is small, so more exhaust gas flows into the flow path, and as a result, the amount of exhaust gas passing through the supercharger inlet pipe 41 decreases. Due to this, the pressure of the air supplied from the supercharger 20 changes, and there is a possibility that the engine main body 10 becomes unstable. On the other hand, in the present embodiment, the on-off valve 51 is opened after the purge valve 52 is closed, thereby suppressing a sudden decrease in the amount of exhaust gas flowing into the supercharger 20 . Step S11 is performed after step S7.

In step S5, when the engine load is lower than the rising switching load ("No" in step S5), the exhaust gas cannot be continuously supplied to the power turbine 30, so the opening and closing valve 51 is kept closed and the extraction valve 52 is opened. status (step S8). Return to step S1 after step S8.

In step S6 , the engine load is calculated based on the engine speed and fuel input amount acquired in step S1 , and it is determined whether or not the engine load is equal to or greater than the down switching load. If it is determined in step S3 that the on-off valve 51 is opened, the process proceeds to step S6 , so it can be considered that the control to open the on-off valve 51 was executed at least in the previous cycle. The on-off valve 51 is opened because the engine load is high, and the exhaust gas can be supplied to the power turbine 30 . Based on this, in step S6 , it is determined whether the engine load is maintained so high that the exhaust gas can be supplied to the power turbine 30 , or whether the engine load is reduced to such an extent that the exhaust gas cannot be supplied to the power turbine 30 . That is, the "down switching load" in step S6 refers to the engine load when the engine load is reduced and the exhaust gas cannot be supplied to the power turbine 30, and in this embodiment, it is set to, for example, 45% load (the maximum load setting of the engine main body). 45% load at 100%). In addition, the difference in the values of the falling switching load and the rising switching load is caused by a so-called hysteresis phenomenon.

In step S6, when the engine load is equal to or greater than the drop switching load (YES in step S6), the state where the exhaust gas can be supplied to the engine main body 10 is maintained, so the on-off valve 51 is kept open and the exhaust valve 52 is kept closed. state (step S9). Step S11 is performed after step S9.

In step S6, when the engine load is lower than the drop switching load ("Yes" in step S6), it is when the exhaust gas cannot be supplied to the power turbine 30, so the on-off valve 51 is closed, and the extraction valve 52 is opened (step S10) . However, in the present embodiment, the closing of the on-off valve 51 and the opening of the purge valve 52 are not performed simultaneously, and the purge valve 52 is opened after a certain time elapses after the on-off valve 51 is closed. Thus, the reason for opening the purge valve 52 after closing the on-off valve 51 is the same as that explained in step S7 , and both are to suppress a sudden decrease in the amount of exhaust gas flowing into the supercharger 20 . Return to step S1 after step S10.

＜Exhaust flow control＞

Next, the exhaust flow rate control will be described. Steps S11 to S16 in FIG. 3 are related to exhaust flow control. The exhaust gas flow rate adjustment control is to control the power turbine 30 efficiently by supplying an appropriate amount of exhaust gas to the supercharger 20 by adjusting the opening degree of the variable nozzle 32 provided in the power turbine 30 . Exhaust flow control is performed after step S7 or step S9. That is, the exhaust flow rate control is performed only when the on-off valve 51 is opened. In addition, whether or not an appropriate amount of exhaust gas can be supplied to the supercharger 20 can be judged based on the scavenging air pressure. That is, when the scavenging pressure is higher than a predetermined value, it can be judged that the amount of exhaust gas supplied to the supercharger 20 is excessive, and when the scavenging pressure is lower than a predetermined value, it can be judged that the amount of exhaust gas supplied to the supercharger 20 is insufficient.

First, the control device 60 sets an appropriate range of scavenging air pressure (step S11 ). Here, FIG. 4 is a graph showing an appropriate range of scavenging air pressure. In FIG. 4 , the horizontal axis represents the engine load, and the vertical axis represents the scavenging air pressure. Among the two straight lines in the figure, the upper straight line represents the upper limit scavenging pressure, and the lower straight line represents the lower limit scavenging pressure. The portion sandwiched between these two straight lines is a range of appropriate scavenging air pressure. For example, as shown in FIG. 4 , when the engine load is L ₁ , the lower limit scavenging pressure is _PL and the upper limit scavenging pressure is P _H . The lower limit scavenging pressure and the upper limit scavenging pressure differ depending on the engine load, and are set to increase as the engine load increases. In actual step S11 , an appropriate range of scavenging air pressure is calculated using a mathematical expression representing a straight line in FIG. 4 .

Next, the control device 60 determines whether or not the actual scavenging air pressure acquired in step S1 is within an appropriate range (step S12 ). That is, it is determined whether or not the actual scavenging pressure is greater than the lower limit scavenging pressure set in step S11 and smaller than the upper limit scavenging pressure. When the scavenging air pressure is within the appropriate range (YES in step S12 ), the opening degree of the variable nozzle 32 is maintained (step S13 ), and the process returns to step S1 . This is because an appropriate amount of exhaust gas can be supplied to the supercharger 20 without changing the opening degree of the variable nozzle 32 . Also, as described above, when an appropriate amount of exhaust gas is supplied to the supercharger 20 by adjusting the opening degree of the variable nozzle 32 , the power turbine 30 must be efficiently driven.

On the other hand, if the scavenging air pressure is not within the appropriate range ("No" in step S12), it is determined whether or not the actual scavenging air pressure is greater than the appropriate range (step S14). That is, it is determined whether or not the actual scavenging air pressure is greater than the upper limit scavenging air pressure. When the scavenging air pressure is larger than the appropriate range (YES in step S14 ), the opening degree of the variable nozzle 32 is increased (step S15 ), and the process returns to step S1 . In this case, more than necessary exhaust gas flows into the supercharger 20 , so control is executed to decrease the amount of exhaust gas flowing into the supercharger 20 side by increasing the opening degree of the variable nozzle 32 . That is, the ratio of the amount of exhaust gas supplied to the supercharger 20 to the amount of exhaust gas discharged from the engine main body 10 is reduced. Moreover, if such control is performed, an appropriate amount of exhaust gas can be supplied to the supercharger 20, so the power turbine 30 must also be efficiently driven.

In step S14 , when it is determined that the actual scavenging air pressure is not greater than the appropriate range (NO in step S14 ), the opening of the variable nozzle 32 is decreased (step S16 ), and the process returns to step S1 . In this case, the actual scavenging air pressure is not greater than the appropriate range, so the actual scavenging air pressure is smaller than the appropriate range (less than the lower limit scavenging air pressure). Then, the amount of exhaust gas in the supercharger 20 is insufficient, so control is performed to increase the amount of exhaust gas flowing into the supercharger 20 side by reducing the opening degree of the variable nozzle 32 . That is, the ratio of the amount of exhaust gas supplied to the supercharger 20 to the amount of exhaust gas discharged from the engine main body 10 increases. Also, if the control is performed in this way, an appropriate amount of exhaust gas can be supplied to the supercharger 20, so the power turbine 30 must also be efficiently driven.

As described above, the engine system 100 according to the present embodiment is configured to include the air extraction pipe 44 and the air extraction valve 52, and when the on-off valve 51 is closed, the air extraction valve 52 is opened to form a circulation of the gas passing through the power turbine 30. flow path. Therefore, even if the power turbine 30 is driven by the crankshaft 11 when the on-off valve 51 is closed, the pressure difference across the power turbine 30 does not increase excessively, and excessive load on the engine main body 10 can be suppressed.

Furthermore, the engine system 100 according to the present embodiment can not only improve the efficiency of the power turbine 30 but also adjust the amount of exhaust gas supplied to the supercharger 20 by the variable nozzle 32 included in the power turbine 30 . Therefore, the overall control and configuration of the engine system 100 can be simplified.

(Modification of the first embodiment)

In the above, it has been described that the on-off valve 51 is opened when the engine main body 10 is rotating forward and the load on the engine main body 10 is greater than the predetermined switching load (hereinafter referred to as "first condition"), and when the engine main body 10 is rotating reversely, or when the engine main body 10 The on-off valve 51 is closed (fully closed) when the load is smaller than the switching load (hereinafter referred to as “second condition”). However, in the second condition, the on-off valve 51 may not be closed but may be set to a small opening. That is, the following control can also be performed: replace the "opening and closing valve closing" of steps S3 and S8 in the flow chart of Fig. "Closing valve" is replaced with "Set the opening and closing valve to a small opening".

The "small opening degree" referred to here refers to an opening degree smaller than the opening degree of the on-off valve 51 under the first condition, and includes the first small opening degree and the second small opening degree. The first small opening degree refers to the opening degree of the on-off valve 51 when the exhaust gas that has passed through the on-off valve 51 is at the boundary between a state in which the power turbine 30 is transported and a state in which the power turbine 30 is driven. Also, the second small opening is smaller than the first small opening and the opening of the on-off valve 51 is in a state where a small amount of exhaust gas flows into the circulation flow path.

As mentioned above, when the on-off valve 51 is closed and the extraction valve 52 is opened, the gas passing through the power turbine 30 passes through the circulation flow path and then passes through the power turbine 30 again. Turbine 30 receives energy and there is a concern of over-boosting. On the other hand, in the second condition, if the on-off valve 51 is set to the first small opening degree or an opening degree close to the first small opening degree, the energy received by the gas in the circulation flow path from the power turbine 30 decreases. , it is possible to suppress an excessive rise in the temperature of the gas in the circulation flow path. Also, in the second condition, when the on-off valve 51 is set to the second small opening degree, a small amount of exhaust gas flows into the circulation flow path, and the gas in the circulation flow path is replaced, so the gas in the circulation flow path can be suppressed. temperature rises excessively.

(Second Embodiment)

Next, a second embodiment will be described with reference to FIG. 5 . Fig. 5 is an overall view of an engine system 200 according to a second embodiment. As shown in FIG. 5 , the engine system 200 according to the present embodiment is different from the engine system 100 according to the first embodiment in that it includes an air intake pipe 47 , an air intake valve 53 , and a power turbine outlet valve 54 . Other than that, its structure is basically the same as that of the engine system 100 according to the first embodiment.

The air introduction pipe 47 is formed to be connected between a part of the power turbine outlet pipe 43 connected with the suction pipe 44 and the power turbine 30 , so that outside air can be introduced into the power turbine outlet pipe 43 . Furthermore, the air introduction valve 53 is provided on the air introduction pipe 47 , and its opening and closing are controlled by the control device 60 . In addition, the power turbine outlet valve 54 is provided between the portion connected to the suction pipe 44 and the portion connected to the air intake pipe 47 in the power turbine outlet pipe 43 , and its opening and closing is controlled by the control device 60 .

Then, the circulation flow path formation control of the present embodiment is formed in such a structure that the air introduction valve 53 is closed when the on-off valve 51 is opened and the suction valve 52 is closed (in the first condition), and the on-off valve 51 is closed and the exhaust valve is opened. The air introduction valve 53 is opened when the exhaust valve 52 is used (in the second condition).

According to the engine system 200 of the present embodiment having the above configuration, even when the on-off valve 51 is closed and the exhaust valve 52 is opened to circulate the gas in the circulation flow path passing through the power turbine 30, the outside air can be passed through the air. Since the introduction pipe 47 is introduced into the power turbine outlet pipe 43 , the gas (air and exhaust gas) in the circulation flow path is replaced, and an excessive rise in temperature of the gas in the circulation flow path can be suppressed.

Also, the power turbine outlet valve 54 is opened when the on-off valve 51 is opened and the purge valve 52 is closed (the first condition), and is closed when the on-off valve 51 is closed and the purge valve 52 is opened (the second condition). By controlling in this way, when the external air is introduced into the power turbine outlet pipe 43 through the air introduction pipe 47 , exhaust gas can be prevented from being introduced from the flue along with this. With this, it is possible to further suppress an excessive rise in the temperature of the gas in the circulation flow path.

(third embodiment)

Next, a third embodiment will be described with reference to FIG. 6 . Fig. 6 is an overall view of an engine system 300 according to a third embodiment. As shown in FIG. 6 , the engine system 300 according to the present embodiment is different from the engine system 100 according to the first embodiment in connection positions of the intake pipe 44 and the power turbine outlet pipe 43 . Other configurations are basically the same as those of the engine system 100 according to the first embodiment.

In this embodiment, the power turbine outlet pipe 43 is connected to a supercharger outlet pipe 46 . Therefore, the exhaust gas passing through the power turbine 30 is introduced into the flue through the power turbine outlet pipe 43 and the supercharger outlet pipe 46 . The suction pipe 44 connects a part of the power turbine inlet pipe 42 downstream of the on-off valve 51 to a part of the supercharger outlet pipe 46 downstream of the part connected to the power turbine outlet pipe.

According to the engine system 300 of the present embodiment, which is configured as above, when the on-off valve 51 is closed and the extraction valve 52 is opened, the circulation flow path as in the first embodiment is not formed, and the gas extracted from the power turbine inlet pipe 42 is not formed. It is discharged to the supercharger outlet pipe 46 . Therefore, the gas passing through the power turbine 30 does not pass through the power turbine 30 again, and the temperature of the gas gradually rises due to the energy of the power turbine 30 to cause an excessive rise.

As mentioned above, although embodiment was demonstrated with reference to drawings, the concrete structure is not limited to these embodiment, and the change of design etc. within the range which does not deviate from the summary of this invention belongs to this invention.

In addition, there are also cases where the above-described operation of the engine system is not performed when an abnormality occurs, such as a part of the engine system is damaged, causing the supercharger and power turbine to reach a dangerous speed, or the scavenging pressure reaches a dangerous scavenging pressure, etc. action. However, it goes without saying that the engine system thereof is included in the present invention when the control according to the present invention is executed normally.

In the engine system according to the embodiment, the power turbine is always connected to the crankshaft through the speed reducer. However, even if, for example, a clutch is provided between the speed reducer and the crankshaft, and the connection between the power turbine and the crankshaft can be released, if If the power turbine is connected to the crankshaft, the problem that an excessive load is applied to the main body of the engine also occurs when the on-off valve is closed.

Also, above, the case where the power turbine inlet pipe is branched from the supercharger inlet pipe has been described, but the power turbine inlet pipe and the supercharger inlet pipe may be formed independently so that each runs from the exhaust pipe to the supercharger or the supercharger. A structure that transports exhaust gas from the exhaust pipe to the power turbine.

In addition, in the above-mentioned embodiment, the case where the engine system is mounted on a ship was described, but even if it is an engine system used for a power generation facility, if it has the structure of this invention, it is a matter of course included in this invention.

Industrial applicability:

According to an engine system according to an aspect of the present invention, waste heat energy can be recovered efficiently, and system simplification can be achieved. Furthermore, according to the engine system of another aspect of the present invention, it is possible to suppress excessive load on the engine main body when the power turbine is not driven by the exhaust gas. Therefore, the engine system of the present invention is useful in the technical field of engine systems.

Symbol Description:

10 engine body;

11 crankshaft;

15 scavenging pipe;

20 booster;

30 power turbines;

32 variable nozzles;

41 Supercharger inlet piping;

42 Power turbine inlet piping;

43 power turbine outlet piping;

44 exhaust piping;

47 air introduction piping;

51 on-off valve;

52 exhaust valve;

53 air introduction valve;

100, 200, 300 engine systems;

101 ships.

Claims (13)

1. An engine system comprising: engine body; a supercharger driven by exhaust gas expelled from said engine block; a power turbine driven by exhaust gases expelled from said engine block; introducing exhaust gas discharged from the engine body into a supercharger inlet pipe of the supercharger; and a power turbine inlet pipe for introducing exhaust gas discharged from the exhaust engine body to the power turbine; The power turbine has a variable nozzle arranged on the inlet side; The engine system is formed into a structure that performs exhaust gas flow control as follows: When the amount of exhaust gas discharged from the engine body decreases, the opening area of the variable nozzle is reduced, thereby increasing the amount of exhaust gas supplied to the supercharger relative to the amount of exhaust gas discharged from the engine body. The proportion of the amount of exhaust gas, and when the amount of exhaust gas discharged from the engine body increases, the opening area of the variable nozzle is increased, thereby reducing the amount of exhaust gas supplied to the supercharger. The ratio of the amount relative to the amount of exhaust gas expelled from the engine block. 2. The engine system of claim 1, wherein: The power turbine inlet pipe is branched from the supercharger inlet pipe, and a part of the exhaust gas in the supercharger inlet pipe is introduced into the power turbine. 3. The engine system according to claim 1 or 2, characterized in that, The engine main body has a scavenging pipe for receiving fresh air boosted by the supercharger; Decrease the opening of the variable nozzle when the pressure in the scavenging pipe is lower than the specified lower limit, and increase the opening of the variable nozzle when the pressure in the scavenging pipe is greater than the specified upper limit The degree of opening is used to control the exhaust flow. 4. The engine system of claim 3, wherein: The predetermined lower limit value and the predetermined upper limit value are set to increase as the load on the engine body increases. 5. An engine system having: engine body; a supercharger driven by exhaust gas expelled from said engine block; a power turbine driven by exhaust gases expelled from the engine block and connected to the crankshaft of the engine block; introducing exhaust gas discharged from the engine body into a supercharger inlet pipe of the supercharger; a power turbine inlet pipe for introducing exhaust gas discharged from the engine main body to the power turbine; An on-off valve installed in the inlet pipe of the power turbine and opened and closed according to the operating conditions of the main body of the engine; an air suction pipe that is connected to a portion of the power turbine inlet pipe on the downstream side of the on-off valve and extracts gas from the power turbine inlet pipe; and an air extraction valve installed in the air extraction piping; The engine system is formed as follows: When the engine body is rotating forward and the load of the engine body is greater than the prescribed switching load, that is, the first condition, the on-off valve is opened and the air extraction valve is closed; When the engine main body is reversed or the load of the engine main body is lower than the predetermined switching load, that is, the second condition, the on-off valve is closed or set to be higher than the on-off valve in the first condition. The opening of the valve is small to a small opening, and the suction valve is opened. 6. The engine system of claim 5, wherein: The power turbine inlet pipe is branched from the supercharger inlet pipe, and a part of the exhaust gas in the supercharger inlet pipe is introduced into the power turbine. 7. An engine system according to claim 5 or 6, characterized in that, The switching load when the load on the engine main body is increasing, that is, an up switching load, is set to be larger than the switching load when the load on the engine main body is decreasing, that is, a down switching load. 8. The engine system of claim 7, wherein: When the load of the engine main body rises and exceeds the rise switching load, the opening and closing valve is opened after closing the exhaust valve. 9. An engine system according to claim 7 or 8, characterized in that, When the load on the engine main body drops below the drop switching load, the on-off valve is closed and then the purge valve is opened. 10. An engine system according to any one of claims 5 to 9, characterized in that, A power turbine outlet pipe for discharging exhaust gas passing through the power turbine is also provided; The suction pipe is connected to the power turbine outlet pipe, and discharges the gas extracted from the power turbine inlet pipe to the power turbine outlet pipe. 11. The engine system according to claim 10, further comprising: In the power turbine outlet pipe, an air introduction pipe capable of introducing outside air into the power turbine outlet pipe is connected between a portion connected to the suction pipe and the power turbine; and an air intake valve provided on the air intake piping; The engine system is formed as follows: The air introduction valve is closed under the first condition, and the air introduction valve is opened under the second condition. 12. An engine system according to any one of claims 5 to 9, characterized in that, A supercharger outlet pipe for discharging exhaust gas passing through the supercharger is also provided; The suction pipe is connected to the supercharger outlet pipe, and discharges the gas extracted from the power turbine inlet pipe to the supercharger outlet pipe. 13. A ship equipped with the engine system according to any one of claims 1 to 12.