JPH04255527A - Two cycle turbo compound engine - Google Patents

Abstract

PURPOSE:To properly improve both exchange of air and recovery efficiency of exhaust energy at the time of scavenging, in a two-cycle engine. CONSTITUTION:An exhaust port 5 is arranged above intake ports 34 provided on the lower side of a cylinder line 33, and a rotary valve 52 which opens only at the time of lowering a piston 2 is mounted in a flow passage from the exhaust port 5. A turbocharger 6 and a recovery turbine 7 are serially connected to the exhaust passage and a changeover valve 43 which is changed over to the recovery turbine 7 side, when intake boost pressure is more than a specified value according to the different pressure between the intake boost pressure of energy 1 and the exhaust gas pressure of the turbocharger 6 is mounted in the flow passage from the exhaust valve 4 provided at a cylinder head 31, so that the driving may be reinforced by supplying the exhaust air to the recovery turbine 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke turbo compound engine that recovers exhaust gas energy.

0002

[Prior Art] Conventional engines in which a piston moves reciprocatingly are roughly divided into 2-cycle and 4-cycle engines. In the 2-cycle engine, after the fuel explosion process, when the piston rises, exhaust gas is discharged and new air is taken in at the same time. It is being done. In a two-stroke engine, it is desired that the amount of air exchanged during the scavenging process be large and instantaneous.

For this reason, for example, a heat insulating material is placed between the cylinder head and cylinder liner of a two-stroke engine to cut off heat conduction from the high-temperature cylinder head, and a supercharger is connected to the intake port provided below the cylinder liner. 2 connected
A cycle adiabatic engine is shown in JP-A-1-182448.

[0004] In addition to preventing temperature increases in the intake port and cylinder liner, supercharging air is fed under pressure to increase air density, thereby increasing the amount of air exchange and speeding it up.

[0005]

[Problems to be Solved by the Invention] The above proposal aims to improve the efficiency of the scavenging process by improving the intake flow path, but the exhaust flow path remains the same. The present invention aims to provide a two-stroke turbo compound engine that improves the scavenging process and exhaust energy recovery.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a two-stroke turbo compound engine in which a turbocharger is disposed in the exhaust flow path of the two-stroke engine to recover exhaust energy. an exhaust valve provided at the head of the cylinder, an exhaust port that opens before the intake port when the piston descends, an on-off valve provided in the flow path from the exhaust port that opens when the piston descends, and the on-off valve. A turbocharger that is driven by exhaust gas from an exhaust port and pumps supercharging air to the engine, and a turbocharger that is driven by exhaust gas from the turbocharger and supplies air based on the differential pressure between the supercharging pressure and the exhaust gas pressure. and a recovery turbine driven by the exhaust flow through the exhaust valve.

[0007]

Embodiments Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a two-stroke turbo compound engine according to the present invention.

In the figure, reference numeral 1 denotes an engine, which is a so-called two-cycle engine in which one combustion cycle is performed during one reciprocation of a piston 2 that moves up and down.

Reference numeral 3 denotes a cylinder, and an exhaust valve 4 is disposed at an exhaust port 32 provided in the cylinder head 31.
A plurality of intake ports 34 are provided through the outer circumferential portion of the cylinder liner 33 corresponding to the bottom dead center position of the piston 2, and the exhaust valve 4 opens the intake port 34 in response to the movement of the piston 2. The valves are configured to open almost simultaneously.

Reference numeral 5 denotes an exhaust port, which is provided above the intake port 34 and opens before the intake port 34 when the piston 2 descends to discharge exhaust gas. A turbocharger 6 is connected through an exhaust pipe 51, and pressurized air generated by the operation of the turbocharger 6 is forced into the cylinder from an intake port 34 through an intake pipe 35. In addition, 52 is a rotary valve that is arranged in the discharge pipe 51 and serves as an opening/closing valve for the flow path, and is operated to open and close the flow path of the discharge pipe 51 by the operation of the actuator 53 corresponding to the reciprocating motion of the piston 2. It is controlled so that it is open when the valve 2 is going down and closed when it is going up.

Reference numeral 7 denotes an exhaust energy recovery turbine, which is connected to a connecting pipe 61 from the turbocharger 6 and driven by exhaust gas, and is equipped with, for example, a generator 71 to convert the exhaust gas energy into electric power. In the middle of 61, there is an inlet pipe 4 that guides exhaust gas using the exhaust pipe 41 as a flow path.
2 is attached to the inlet of the inlet pipe 42, and a switching valve 43 is installed at the inlet of the inlet pipe 42.
is located. Further, 44 is a valve switch that opens and closes the switching valve 43, and when the switching valve 43 closes the introduction pipe 42, the exhaust gas flowing through the exhaust pipe 41 is the exhaust gas from the recovery turbine 7. They merge and are released to the outside.

Note that 62 is an exhaust gas pressure sensor that detects the exhaust gas pressure of the turbocharger 6, and 36 is a boost pressure sensor that detects the supercharging pressure from the turbocharger 6. Detection signals from these sensors are sent to the controller 8. The differential pressure between the pressure values based on both signals is calculated.

The controller 8 is composed of a microcomputer, and is equipped with a central control unit for performing arithmetic processing, various memories for storing arithmetic processing procedures and control procedures, input/output ports, etc. When the signal is input, a predetermined calculation is performed, and based on the stored procedure, for example, if the detection signal from the boost pressure sensor 36 is higher than the detection signal from the exhaust gas pressure sensor 62 by a predetermined value or more, the switching valve 43 The rotary valve 52 and the exhaust valve 4 are controlled to open and close according to the reciprocating movement of the piston 2.

Next, the operation of this embodiment configured as described above will be explained.

During the expansion stroke of the engine 1, the piston 2 is compressed, the exhaust port 5 is opened, and high-pressure gas is injected into the turbocharger 6 at once through the rotary valve 52 when the valve is opened, so that the cylinder internal pressure rapidly increases. descend. In this case, the turbocharger 6 and the recovery turbine 7 are connected to the exhaust flow path, and the exhaust pressure is high, but since the explosion pressure of the fuel is high, the turbocharger 6 and the recovery turbine 7
is driven and ejected.

[0017] Next, the piston 2 moves approximately 20° before the bottom dead center.
At this point, the rotary valve 52 is closed by the actuator 53, and exhaust from the exhaust port 5 ends. However, at this point, the intake port 34 and the upper exhaust valve 4 are opened almost simultaneously, so the turbocharger 6 is forced into the cylinder via the intake pipe 35 and intake port 34, and the residual gas is sent to the exhaust pipe 4 via the opened exhaust port 32.
1, and the inside of the cylinder is replaced with fresh air.

In this case, the differential pressure is calculated based on both detection signals from the boost pressure sensor 36 that detects supercharging pressure and the exhaust gas pressure sensor that detects the exhaust gas pressure of the turbocharger 6. When the supercharging pressure is high, the switching valve 43 provided in the middle of the exhaust pipe 41 is opened, and the residual gas discharged into the exhaust pipe 41 is transferred to the recovery turbine 7 via the introduction pipe 42. The exhaust energy is efficiently recovered by introducing the exhaust gas into the exhaust gas of the turbocharger 6 and energizing the recovery turbine 7.

FIG. 2 is an explanatory diagram of the intake/exhaust timing in this embodiment, in which the exhaust port, which opens before the intake port as the piston descends, is opened by opening the rotary valve to release exhaust gas. The cylinder head exhaust valve opens at approximately the same timing as the intake port opens to improve air supply, and the rotary valve closes the exhaust port when the piston rises. .

Although the present invention has been described using the above embodiments, various modifications can be made within the scope of the invention, and these modifications are not excluded from the scope of the invention.

[0021]

As explained in the above embodiments, according to the present invention, an exhaust port is provided which opens before the intake port when the piston descends in a two-stroke engine, and is opened only when the piston descends. The exhaust energy through the exhaust port drives a turbocharger to forcefully send supercharged air to the engine, and the exhaust gas from the turbocharger operates a recovery turbine, and further,
Since the exhaust gas through the exhaust valve at the cylinder head is supplied to the recovery turbine according to the pressure difference between the pressure of the supercharging air and the pressure of the exhaust gas of the turbocharger, the blow of high-pressure gas during the explosion stroke is The down energy is introduced into the turbocharger to efficiently drive the turbocharger and recovery turbine, and the exhaust gas generated by the scavenging air through the exhaust valve can also energize the rotation of the recovery turbine. The effect is that air exchange can be carried out well and that the exhaust energy recovery effect is improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing an embodiment of a two-stroke turbo compound engine according to the present invention.

FIG. 2 is an explanatory diagram of intake/exhaust timing in this embodiment.

[Explanation of symbols]

1...Engine 2...Piston 3...Cylinder 4...Exhaust valve 5...Exhaust port 6...Turbocharger 7...Recovery turbine 8...Controller 36...Boost pressure sensor 52...Rotary valve 62...Exhaust gas pressure sensor

Claims (2)

[Claims] Claim 1: In a two-stroke turbo compound engine in which a turbocharger is placed in the exhaust flow path of the two-stroke engine to recover exhaust energy, an exhaust valve installed at the head of the cylinder of the engine and an exhaust valve that precedes the intake port when the piston descends. an exhaust port that opens when the piston moves downward; an on-off valve that is installed in the flow path from the exhaust port and opens when the piston descends; and supercharged air is pumped to the engine through the on-off valve driven by exhaust gas from the exhaust port. a turbocharger that is driven by exhaust gas from the turbocharger, and a recovery turbine that is driven by the exhaust flow through the exhaust valve that is supplied based on the differential pressure between the boost pressure and the exhaust gas pressure. A 2-stroke turbo compound engine with the following features. 2. The two-stroke turbo compound engine according to claim 1, wherein a rotary valve is employed as the on-off valve.