JPH0519015B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a turbo compound engine as a highly supercharged engine, and particularly to an engine braking force equal to or greater than that of a non-supercharged engine with the same output. Regarding the turbo compound engine.

[Prior Art] In general, an engine equipped with a supercharger has better fuel efficiency than a non-supercharged engine with a larger displacement, has the same or higher output performance, and is lightweight and compact. It has excellent advantages such as Highly supercharged engines and turbo compound engines take this advantage even further. The turbo compound engine is
As shown in Figure 8, exhaust gas from engine b is first recovered as supercharging work of turbocharger c, and then exhaust gas discharged from turbocharger c is recovered as power work of power turbine d. It was designed to do so. As a result, the output performance, fuel efficiency, and gain of engine b can be comprehensively improved. In order to further improve the overall performance of the turbo compound engine, it is necessary to increase the expansion ratio of the turbo supercharger c and the power turbine d. That is, the further the boost pressure is increased, the more useful the turbo compound engine can be.

As an earlier conventional example of this type,
There is an internal combustion engine described in Publication No. 157941.

As shown in FIG. 9, this internal combustion engine has an exhaust passage e between the turbocharger c ₁ and the power turbine d ₁ .
Bypass passage f that detours around the power turbine d ₁
and a switching valve h that closes the exhaust passage e and opens the bypass passage f depending on the amount of depression of an accelerator pedal that operates the engine (not shown). It is configured by providing.

[Problems to be solved by the invention] The internal combustion engine described above knows from the amount of depression of the accelerator pedal that the exhaust gas flow rate is small and the exhaust gas energy is small, and when the exhaust gas engine is small, the exhaust gas is routed to the bypass passage. This is an attempt to prevent a decrease in output performance by increasing the back pressure acting on the turbine of the turbocharger _c1 by bypassing it to f.

However, when adopting the above-mentioned internal combustion engine in a vehicle, securing engine braking force (exhaust braking force) commensurate with the increase in output performance remains an issue. As shown in Figure 7, this is the engine speed for non-supercharged engines and highly supercharged engines.
It can be known from the relationship between engine output Pme and engine braking force Pmf with respect to Ne.

In the figure, the solid line indicates output performance, and the broken line indicates engine braking force.

Here, 100% rated rotation speed as representative rotation speed
Looking at the relative braking force (engine braking force/engine output) at N100%, B _N /S _N >
It can be seen that there is a relationship of B _T /S _T.

However, B _N ...Engine braking force of a non-supercharged engine, S _N ...Engine output of a non-supercharged engine B _T ...Engine braking force of a highly supercharged engine S _T ...Engine output of a highly supercharged engine. By increasing the supply pressure value, the relative braking force becomes smaller. Securing engine braking force is an essential element not only for vehicle operability but also for safe driving, and is also an important issue for taking advantage of the advantages of turbo compound engines.

[Means for Solving the Problems] The present invention aims to solve the above problems. This invention relates to a power turbine interposed in an exhaust passage, a fluid passage having one end connected to an upstream side of the power turbine in the exhaust passage and the other end connected to a downstream side of the power turbine in the exhaust passage, and a crankshaft between the power turbine and the engine. A forward rotation gear train that connects the forward rotation gear train and is configured to return power from the power turbine to the engine crankshaft, and a forward rotation gear train that connects the forward rotation gear train with the
a first clutch that is switched to OFF, a gear train for reversing that connects the power turbine and the crankshaft and configured to reverse the rotational force of the crankshaft and transmit it to the power turbine; Turn on the gear train.
A second clutch that is switched OFF, and when the exhaust brake is activated and the first clutch is switched OFF and the second clutch is switched ON, the exhaust passage upstream of the fluid passage is closed and the fluid passage is opened. The apparatus is equipped with a flow path switching means configured as follows.

[Operation] During normal operation, the first clutch is switched on and the second clutch is switched off, so the power turbine collects the exhaust engine and transmits it to the engine crankshaft via the forward rotation gear train. .

When the exhaust brake is applied, the first clutch is OFF and the second clutch is OFF.
When the clutch is turned ON, the flow path switching means closes the exhaust passage on the upstream side of the fluid passage, and narrows and opens the exhaust passage and the fluid passage immediately upstream of the power turbine. As a result, the rotation of the crankshaft is reversed by the reversing gear train and transmitted to the power turbine, which is originally intended for energy recovery. For this reason, the power turbine performs negative work, that is, pump work, by taking in air from the exhaust passage downstream of the power turbine and pumping it into the fluid passage.
Therefore, during exhaust braking, a large engine braking force can be created by adding the engine motor friction, pump work (negative work), and exhaust braking force.

[Embodiment] A preferred embodiment of the turbo compound engine of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is an engine, 2 is an intake manifold, and 3 is an exhaust manifold.

As illustrated, an exhaust passage 4 is connected to the exhaust manifold 3, and an intake passage 5 is connected to the intake manifold 2.

A turbine 10a of a turbocharger 10 is disposed in the exhaust passage 4, and a compressor 10b of the turbocharger 10 is disposed in the intake passage 5. A power turbine 12 is installed in the exhaust passage 4 on the downstream side of the turbocharger 10 to recover exhaust gas energy.

Incidentally, the purpose of the turbo compound engine of the present invention is to ensure engine braking force in accordance with the output performance of the engine 1. In order to increase the engine braking force, it is considered effective to directly or indirectly apply resistance to the crankshaft 15 to prevent its rotation, thereby causing the crankshaft 15 to perform large negative work.

Therefore, in the turbo compound engine of the present invention, the power turbine 12 is reversed when the exhaust brake is activated, thereby causing the power turbine 12 to perform large negative work.

First, a configuration for rotating the power turbine 12 forward and reverse will be explained.

As shown in FIG. 1, the output shaft 13 of the power turbine 12 is connected to the crankshaft 15 of the engine 1 via a plurality of rows of forward rotation gear trains 19. A fluid coupling 21 is provided. A forward rotation electromagnetic clutch 24a is interposed in the gear train 23 between the gear train 22 having the fluid coupling 21 and the row of the crankshaft 15. Therefore, when the forward rotation electromagnetic clutch (first clutch) 24a is "ON", rotation is transmitted from the power turbine 12 to the crankshaft 15.

Furthermore, the output shaft 13 of the power turbine 12
is connected to the crankshaft 15 by a reverse gear train 20 provided in parallel to the forward gear train 19, and this reverse gear train 20 is provided with a reverse gear train 26 in contrast to the forward gear train 19. It is being A reverse electromagnetic clutch (second clutch) 24b is interposed between the reverse gear train 26 and the crankshaft 15 train. When the reversing electromagnetic clutch 24b is "ON", rotation is reversed and transmitted from the crankshaft 15 to the power turbine 12. Here, when the forward rotation electromagnetic clutch 24a is "ON", the reverse rotation electromagnetic clutch 24b is configured to be "OFF", so that when one gear train is connected, the other gear train is disconnected. configured.

Power turbine 1 of each gear train 19, 20
A fluid coupling 21 is interposed in each gear train on the second side, and this fluid coupling 21 is connected between a pump car 21a on the input side (power turbine side) and a pump car 21b on the output side (crankshaft side). The pump car 21 on either the input or output side is used to circulate hydraulic oil.
a, 21b is activated, the other pump car 2
Hydraulic oil is supplied to 1a and 21b to transmit rotational output.

Generally, the shape of the impeller of the power turbine 12 is designed to work efficiently in the forward rotation direction, and when the power turbine 12 is rotated in the reverse direction, a large amount of force is generated relative to the crankshaft 15. In order to provide resistance, this embodiment is constructed as follows.

As shown in FIG. 2, one end is connected to the exhaust passage 4 between the power turbine 12 and the turbine 10a of the turbocharger 10, and the other end is connected to the exhaust passage 4 downstream from the power turbine 12. A connected fluid passage 25 is formed, and this fluid passage 2
A flow path switching means 30 is provided at a connection portion upstream of the power turbine 12 of No. 5.

In this embodiment, the flow path switching means 30 is the first
As shown in FIG. 2, the rotary valve 31 includes a rotary valve 31 provided at the connection portion, and a drive device 32 that operates the rotary valve 31. As shown in FIGS. 2 and 3, the rotary valve 31 houses a rotatable rotor 31b in a casing 31a, and has two first ports A and a second port B formed in the rotor 31b. configured. The port diameter d ₁ of one first port A is equal to the passage diameter d ₀ of the exhaust passage 4 , and the port diameter d ₂ of the other second port B is smaller than the passage diameter d ₃ of the fluid passage 25 . On the other hand, a port 31c, which becomes a part of the exhaust passage 4, is opened in the casing 31a. The rotational positional relationship between the first port A and the second port B is set such that when the exhaust passage 4 and the first port A are connected, the exhaust passage 4 and the fluid passage 25 are disconnected. .

The drive device 32 that switches and controls the rotary valve 31 is configured as follows.

As shown in FIGS. 1 and 2, the rotor 31
A lever member 35 having one end fixed thereto is connected to b, and the operating rod 33 of the actuator 34 is connected to the free end of the lever member 35 extending outward in the radial direction of the exhaust passage 4. be done.

Reference numeral 36 shown in FIG. 1 is a fluid supply device, and this fluid supply device 36 and the operating chamber 37 of the actuator 34 are connected by a fluid supply passage 39. A solenoid valve 40 is interposed therein, which brings the operating chamber 37 and fluid supply passage 39 into communication when energized. This solenoid valve 40 is energized when all switches of the engine 1, including a neutral sensor switch 41, a clutch operation switch 42, and an exhaust brake switch 43, are turned on. 45 is a DC power source such as a battery.

46 is an electromagnetic clutch switch for forward rotation, and 47 is an electromagnetic clutch switch for reverse rotation. The contact of the electromagnetic clutch switch 46 for forward rotation is a normally closed contact (b contact), and the electromagnetic clutch switch 47 for reverse rotation is a normally open contact (a contact).

Next, the operation of the turbo compound engine of the present invention will be explained based on the accompanying drawings.

As shown in FIG. 1, when the exhaust brake switch 43 is OFF, the solenoid valve 40 is OFF, so as shown in FIG. The side exhaust passage 4 is connected via the first port A. Exhaust gas from the engine 1 is sent to an exhaust manifold 3 and an exhaust passage 4 to a turbo supercharger 10
Exhaust gas energy is recovered by the turbine 10a. The turbine 10a rotationally drives the compressor 10b on the same axis, so that supercharged air is sent into the cylinders of the engine 1. Exhaust gas exiting the turbine 10a of the turbocharger 10 provides rotational driving force to the power turbine 12. That is, exhaust gas energy is recovered again in this power turbine 12. Here, since the forward rotation electromagnetic clutch switch 46 is "ON" at this time, the exhaust gas energy recovered by the power turbine 12 is transmitted to the crankshaft 15 via the forward rotation gear train 19 and the fluid coupling 21, and rotates. Used as energy.

Next, a description will be given of when the exhaust brake is activated.

When the exhaust brake is activated, the neutral sensor switch 41, clutch operation switch 42, and exhaust brake switch 43 are all ON, and at this time, the reverse electromagnetic clutch switch 47 is activated.
is “ON”, so the solenoid valve 40 is turned on at this time.
When turned ON, the working fluid is supplied from the fluid supply device 36 to the operating chamber 37 of the actuator 34. As a result, the operating rod 33 operates the rotary valve 31 via the lever member 35, closes the exhaust passage 4, and connects the exhaust passage 4 downstream of the rotary valve 31 and the fluid passage 25 via the second port B. communicate. Therefore, in a state where the power turbine 12 is no longer given rotational force by the exhaust gas, the reverse gear train 20 and the fluid coupling 21
The rotational force of the crankshaft 15 is transmitted to the power turbine 12 via. That is, the power turbine 12
As shown in FIG. 5, the compressor is reversed and becomes an inefficient compressor that sends air from the exhaust passage 4 downstream of the power turbine 12 to the connection part of the fluid passage 25. Further, the flow rate at which the gas sent to the fluid passage 25 is throttled by the second port B is increased. The air stirring work and compressor work of the power turbine 12 result in large negative work for the crankshaft 15. Therefore, when the exhaust brake is activated, a large engine braking force is created by adding this negative work, the negative work of the exhaust brake, and engine friction. The configuration as an exhaust brake is achieved by the operation of an exhaust brake valve (not shown) provided downstream of the exhaust manifold 3, and when this brake valve is fully closed, the exhaust resistance increases, that is, the pumping work is reduced. The increase becomes engine braking force by the exhaust brake valve.
Here, the diameter of the second port B is the power turbine 12
The relationship shown in FIG. 4 has been confirmed between port diameter d ₂ and engine braking force Pmf, that is, negative work.
That is, the port diameter d ₂ at which the engine braking force is maximized by the power turbine 12 (see Fig. 5).
can be obtained.

FIG. 6 shows the engine braking force performance of a base engine without the turbocharger 10 and power turbine 12 and a turbo compound engine equipped with them.

As shown in the figure, A shows the motor friction of the base engine, and C shows the motor friction of the turbo compound engine.

B shows the engine braking force performance for a turbo compound engine when the exhaust passage 4 between the turbo supercharger 10 and the power turbine 12 or downstream of the power turbine 12 is closed, and D shows the engine braking force performance when the exhaust brake is activated for the base engine. Indicates engine braking performance. Ho shows the engine braking force performance of a turbo compound engine when the exhaust brake is activated.

From these results, it can be seen that engine braking force performance is superior in engine braking force, but the engine braking force is small for a turbo compound engine with high output performance. Therefore, in a turbo compound engine, the engine braking force performance when the exhaust passage 4 between the turbo supercharger 10 and the power turbine 12 is closed and the power turbine 12 performs the work of stirring air in the normal rotation direction is as follows. It can be seen that there is an improvement in Fig. 7 shows the case in which the power turbine 12 performs compression work in the normal rotation direction in Fig. 5, and it can be seen that a large engine braking force can be obtained. On the other hand, it can be seen that Q, which indicates the engine braking force performance of the turbo compound engine of the present invention, has a good start-up (responsiveness) and can obtain a larger engine braking force.

In the embodiment of the present invention, the exhaust passage 4 and the fluid passage 25 are switched by the rotary valve 31. However, the present invention is not limited to this. When a driving force in the direction is transmitted, an on-off valve that completely closes the exhaust passage 4 upstream of the connection part of the fluid passage 25 and a throttle valve that narrows the passage diameter of the fluid passage 25 to a predetermined opening are provided. They may be linked. Furthermore, the fluid passage 25 may be narrowed to a predetermined opening degree in advance, and the exhaust passage 4 upstream of the fluid passage 25 may be opened and closed.

[Effects of the Invention] As is clear from the above explanation, the turbo compound engine of the present invention can exhibit the following excellent effects.

(1) A power turbine that is normally rotated by exhaust gas and recovers gas energy is interposed in the exhaust passage, and a fluid passage that bypasses the turbine is connected to the exhaust passage upstream of the turbine, so that when the exhaust brake is activated, In addition, since the turbo compound engine is configured with a flow path switching means that closes the exhaust passage upstream of the fluid passage and opens the fluid passage when driving force in the reverse direction is transmitted from the crankshaft to the turbine, the exhaust gas During braking, a large engine braking force can be generated by adding engine friction, power turbine negative work, and exhaust braking force.

(2) Sufficient engine braking force can be secured to demonstrate the high performance of the turbo compound engine, greatly improving reliability.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing a preferred embodiment of the turbo compound engine of the present invention, Figures 2 and 3 are detailed views of the main parts of Figure 1, and Figure 4 is the diameter of the second port B of the rotary valve. Fig. 5 is a schematic diagram showing the gas flow of the power turbine, Fig. 6 is a graph showing the engine braking force performance, and Fig. 7 is a graph showing the relationship between non-supercharged engine and highly supercharged engine. Graphs showing a comparison of engine braking force performance with that of the engine, and FIGS. 8 and 9 are schematic diagrams showing conventional examples. In the figure, 1 is an engine, 4 is an exhaust passage, 12 is a power turbine, 25 is a fluid passage, 30 is a switching valve,
31 and a drive device 32.

Claims (1)

[Scope of Claims] 1. A power turbine interposed in an exhaust passage, a fluid passage whose one end is connected to an upstream side of the power turbine in the exhaust passage and the other end is connected to a downstream side of the power turbine in the exhaust passage, and the above-mentioned power turbine. A gear train that connects the engine crankshaft and is configured to return power from the power turbine to the engine crankshaft, and a first gear train that switches the forward rotation gear train ON/OFF.
A clutch, a reversing gear train that connects the power turbine and the crankshaft and is configured to reverse the rotational force of the crankshaft and transmit it to the power turbine, and turning on and off the reversing gear train. and a second clutch that is switched to close the exhaust passage upstream of the fluid passage and open the fluid passage when the exhaust brake is activated and the first clutch is switched OFF and the second clutch is switched ON. A turbo compound engine characterized by comprising a flow path switching means configured to. 2 The flow path switching means operates when the exhaust brake is activated, the first clutch is switched OFF, and the second clutch is turned OFF.
The invention of the above-mentioned patent claim comprises a switching valve that closes the exhaust passage and opens the fluid passage to a predetermined opening degree when the clutch is turned ON, and a drive device that drives the switching valve. Turbo compound engine according to scope 1. 3. The switching valve is a rotary valve having a first port having the same diameter as the exhaust passage and a second port smaller than the fluid passage, and when the exhaust brake is activated and the first clutch is switched OFF and the second clutch is The above patent claim comprises a rotary valve configured to be switched by the drive device to connect the second port and the fluid passage and disconnect the first port and the exhaust passage when turned ON. Turbo compound engine according to range 2.