JP2015129501A - engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which a conventional premixing and compression ignition type engine generates a loud engine sound, and needs to be switched to another ignition mode to operate for large output and thereby has effects on high efficiency limited so as to have a narrow operable region on a large-output side.SOLUTION: There is provided a four-cycle, two-axial horizontally-opposed piston, opposed-cylinder engine, and a free piston 117 is provided in a combustion chamber, which is divided into two chambers 103, 109. When ignition is performed with an ignition plug 113 of one combustion chamber, the free piston 117 moves toward the other combustion chamber 103 through expansion, and a mixed gas in the other combustion chamber is compressed by the free piston 117 and exceeds an ignition temperature to be ignited. The ignition is performed at the point of time when a crank angle is 10°, and delay angle effect can be obtained. An exhaust emission of high temperature need not be mixed with the mixed gas, so a mixed air temperature at the start of compression is low and the delay angle effect is further added so as to efficiently convert momentary large output into motion.

Description

  Technical field related to engine compression ignition.

The premixed compression ignition (HCCI) engine is ignited and expanded at a high compression ratio because most of the air-fuel mixture reaches the ignition temperature simultaneously due to adiabatic compression and instantly ignites, resulting in less heat loss to the outside. Combustion efficiency is higher than that of a spark plug type (SI) engine, and practical use is also desired to suppress global warming due to depletion of fossil fuels and CO2 emissions. In the conventional HCCI method, the pressure and temperature in the combustion chamber are measured by a sensor, and the specific heat ratio is calculated so that the combustion exhaust gas is mixed into the optimal mixture amount supply air and the ignition temperature is reached at the top dead center. Was adjusting. It is also known that the intake angle can be retarded by lowering the intake air temperature.
Patent Document 1 discloses an opposed piston facing cylinder (OPOC) engine with a free piston. The free piston is mainly used in a power generation engine that generates power by rotating a generator by compressing or pressurizing a fluid.

  Japanese Patent No. 4901659

In the HCCI engine that has been proposed in the past, almost all of the air-fuel mixture explodes instantly at the top dead center of the piston, so the sound is loud and the engine is destroyed at high output. In order to increase the output, it is necessary to switch to another ignition mode for operation, and the range of high-efficiency operation is narrow, making it difficult to put it to practical use.
Moreover, since the OPOC engine with a free piston as in Patent Document 1 cannot be directly mechanically connected to the crank of the engine, it has been practically difficult for an automobile engine. Another document discloses an indirect connection via a flywheel in mechanical connection. However, when a flywheel is used, there is a problem of weight or a decrease in rotational speed due to friction. It was difficult to store in the engine room. Therefore, there is a demand for a highly silent HCCI engine that is mechanically synchronized with the crank and that can handle a large output.
The biggest problem for practical use is that the operable range in the HCCI mode is narrow, and in particular, it is necessary to widen the operable range to the high output side.

  In the first means, another combustion chamber (hereinafter referred to as “HCCI side combustion chamber”) connected to the combustion chamber provided with the ignition means (hereinafter referred to as “SI side combustion chamber”) is provided, and the connection portion is provided. Gas in both combustion chambers is isolated by a free piston that is slidable in the cylinder without being mechanically connected to the outside provided, and by plug ignition and expansion of the SI side combustion chamber toward the HCCI side combustion chamber of the free piston In an engine that compresses and ignites an air-fuel mixture in the HCCI side combustion chamber by moving, the pistons of both combustion chambers except the free piston are connected to each other by a mechanical mechanism.

  In this means, a plurality of combustion chambers are connected at the connecting portion, and a free piston for isolating the gas in each combustion chamber is provided at the connecting portion. At least one of the plurality of combustion chambers is provided with an SI combustion chamber that is ignited by an ignition plug. In the other combustion chambers, the combustion is compressed by the free piston at the connecting portion by the gas expanded by ignition by the ignition means of the SI combustion chamber. The HCCI combustion chamber mixture gas ignites. By delaying the SI side ignition timing, a retarding effect can be given to the ignition on the HCCI side, and a large output can be efficiently converted into kinetic energy.

  In the second means, a partition wall is provided between the piston of the SI side combustion chamber and the free piston, and an exhaust valve and ignition means are provided in a space between the free piston and the partition wall (hereinafter referred to as “combustion ignition chamber”). A space between the piston and the piston (hereinafter referred to as the “compression chamber”) is provided with an air supply valve, and a partition wall is provided with a hole connecting the combustion ignition chamber and the compression chamber so that the compression chamber pressure is higher than the combustion ignition chamber pressure. A valve is provided that opens and closes when it is low.

  In this means, the air-fuel mixture compressed in the compression chamber is temporarily stored in the combustion ignition chamber, and the SI-side air-fuel mixture is ignited by the spark plug at an arbitrary delay angle on the HCCI side, and the free piston is pushed. Let the side ignite compression. In this means, since the combustion ignition chamber volume can be made constant, misfire can be prevented and retarding control can be performed over a wide range.

  By igniting when the piston is in the delayed position, it is possible to efficiently convert the sudden pressure rise of compression ignition into kinetic energy, and the sound is quiet and a wide range of output characteristics can be realized. In addition, since an in-cylinder sensor, a microcomputer, and an exhaust gas recirculation mechanism are not required for ignition, it is inexpensive and can avoid danger at the time of failure of the microcomputer, and has high reliability and safety. In addition, compared with a cylinder having the same combustion chamber volume with a single piston, the air-fuel mixture that can be regarded as one with a free piston is expanded by two pistons, so that a large retardation effect is obtained.

Side cross-sectional explanatory drawing explaining the HCCI engine Explanatory drawing explaining the stroke of HCCI engine Side cross-sectional explanatory drawing explaining another HCCI engine Side cross-sectional explanatory drawing explaining another HCCI engine

  A first embodiment of the present invention is shown in FIGS. FIG. 1 is a side sectional view for explaining an HCCI engine of the present invention. 101 is a cylinder, 102 is a piston ring, 103 is an HCCI combustion chamber, 104 is an air supply valve 1, 105 is a sliding restriction convex part, 106 is a stabilizer, 107 is a sliding restriction convex part, 108 is an air supply valve 2, 109 is an SI combustion chamber, 110 is a piston 2, 111 is a connecting rod, 112 is a piston ring, 113 is a spark plug, 114 is an exhaust valve 2, 115 is an oil-impregnated metal, 116 is a piston ring, 117 is a free piston, 118 is exhaust Valves 1 and 119 are guide grooves, 120 is a glass fiber, 121 is a piston 1 and 122 is a connecting rod. FIG. 2 is an explanatory diagram illustrating the stroke of the HCCI engine of the present invention.

  As shown in FIG. 1, a free piston (117) is provided in the combustion chamber of a four-cycle two-axis horizontal OPOC gasoline engine, and the opposing piston is connected to the crank with a phase difference. The process is shown in FIG. The ratio of the SI side bore / stroke product to the HCCI side bore / stroke product was 1: 2. The pistons in both combustion chambers have a structure in which two shafts are connected by a gear to transmit power to the rotating shaft. The SI-side ignition timing is performed at the retarded position of the HCCI-side piston. The intake start timing is performed at a crank angle at which the sum (S) of both the combustion chamber volumes on the SI side and the HCCI side is minimized. The exhaust start timing and the compression start timing are performed at a crank angle at which the sum (S) of both combustion chamber volumes is maximized.

Ｓ：両燃焼室ピストンの各クランク角におけるストローク和
（ＨＣＣＩ側ストロークを１としたときの値）
ａ：両燃焼室ピストンのストローク比で小さい方
ｂ：両燃焼室ピストンのストローク比で大きい方
θ：クランク角

S: Sum of strokes at each crank angle of both combustion chamber pistons
(Value when HCCI side stroke is 1)
a: Smaller stroke ratio of both combustion chamber pistons b: Larger stroke ratio of both combustion chamber pistons θ: Crank angle

For example, when the air-fuel mixture in the SI combustion chamber (109) is ignited by the SI-side ignition plug (113) at a crank angle of 10 °, it expands and pushes the free piston (117) toward the HCCI side, thereby causing the HCCI-side combustion chamber ( 103) The air-fuel mixture is compressed and ignited, and the piston with a large crank angle is pushed down by pushing the free piston (117) to SI again. The free piston (117) is provided with a piston ring (116) attached so that a stabilizing plate (106) sliding in the guide groove (119) intersects at a right angle. Furthermore, sliding of the free piston (117) is restricted by a sliding restriction convex part (105, 107) in front of the valve (104, 108, 118, 114). An oil impregnated metal (115) is provided on the sliding portion. An oil impregnated metal (115) can be used because only the force in the sliding direction is applied to the free piston and no force is applied in the direction of pushing the cylinder wall. The material is preferably a copper-based material with good heat transfer. Furthermore, the free piston (117) has a long shape in the direction of both combustion chambers (103, 109) so as not to reduce the compression ratio, and a glass fiber (120) is provided inside to reduce weight and improve responsiveness. Provided.
In the present invention, the air-fuel mixture that can be regarded as one across the free piston is expanded by the two pistons as compared with a cylinder having the same combustion chamber volume with a single piston, so that there is a 1.5 times retarding effect. Since it is not always necessary to mix the burned exhaust gas, when the exhaust gas is not mixed, a large retardation effect can be obtained because the mixture temperature at the start of compression is low. Furthermore, by adding to the mechanical retardation of the present invention, a larger retardation effect can be obtained, and the operable range can be greatly expanded on the large output side. Further, by changing the ignition timing, the retarding effect can be changed within a range where no misfire occurs.

  A second embodiment of the present invention is shown in FIG. FIG. 3 is a side sectional view for explaining the HCCI engine of the present invention. 301 is a cylinder, 302 is an HCCI combustion chamber, 303 is an intake valve 1, 304 is a free piston, 305 is an exhaust valve 2, 306 is a combustion ignition chamber, 307 is an intake valve 2, 308 is a piston 2, 309 is a compression chamber , 310 is a partition wall, 311 is a check valve, 312 is a spark plug, 313 is an exhaust valve 1, and 314 is a piston 1.

  According to the present invention, a partition wall (310) is provided in a space between the free piston (304) and the piston 2 (308) in the engine of the first embodiment, and an exhaust valve 2 (305) is provided in the combustion ignition chamber (306). ) And a spark plug (312), and a check valve (311) that opens when the pressure in the compression chamber (309) is higher than the pressure in the combustion ignition chamber (306) and closes when the pressure is low is provided in the partition wall. The structure.

From the above structure, the piston 2 (308) is mechanically connected to the HCCI-side piston 1 (314), and compresses the air-fuel mixture from the air supply port. When the compressed air-fuel mixture pressure becomes larger than the pressure in the combustion ignition chamber (306), the check valve (311) is opened and the air-fuel mixture is supplied into the combustion ignition chamber (306). When the piston 2 (308) starts to descend, the pressure in the compression chamber (309) decreases, the check valve (311) closes, and the crank angle of the HCCI side piston 1 (314) starts from the top dead center (0 °). Is ignited by the ignition flag (312) at a larger crank angle. The pressure in the combustion ignition chamber (306) rises and pushes the free piston (304) to ignite the air-fuel mixture in the HCCI combustion chamber (302). The exhaust valve 2 (305) opens and closes in synchronization with the HCCI side exhaust valve 1 (313).
In the present invention, since the combustion ignition chamber (306) has a constant volume, it is possible to prevent misfiring of the combustion ignition chamber (306) at the time of a large delay angle, so that the ignition timing can be controlled in a relatively wide range.

  In the first and second embodiments, during the warm-up operation, ignition may be performed using a spark plug (not shown) on the HCCI side. The crank angle shown in FIG. 2 is a delay time from ignition to expansion, a delay time of pressure transmission by the free piston, an ignition timing advance angle at high speed rotation on the SI side, etc. Is not reflected in the crank angle. Furthermore, in the present invention, since a free piston and ignition means may be provided at a connecting portion connecting a plurality of combustion chambers, the horizontal OPOC type is not necessary, and an inverted V type, for example, may be used. In still another example, a parallel two-tube configuration as shown in FIG. 4 may be used. 401 is an exhaust valve, 402 is an intake valve, 403 is an HCCI combustion chamber, 404 is a free piston, 405 is a spark plug, 406 is an intake valve, 407 is an exhaust valve, 408 is a connecting rod, 409 is a connecting rod, 410 is a piston, 411 is a piston, and 412 is an SI combustion chamber.

  It can be applied to power engines used in automobiles, aircraft, ships, power generation, etc.

S Stroke sum a, b Stroke ratio θ Crank angle 101, 301 Cylinder 102, 112, 116 Piston ring 103, 302, 403 HCCI combustion chamber 104, 303 Air supply valve 1
105, 107 Sliding restriction convex portion 106 Stabilizing plate 108, 307 Air supply valve 2
109, 412 SI combustion chamber 110, 308 Piston 2
111, 122, 408 Connecting rod 113, 312, 405 Spark plug 114, 305 Exhaust valve 2
115 Oil impregnated metal 117, 304, 404 Free piston 118, 313 Exhaust valve 1
119 Guide groove 120 Glass fiber 121, 314 Piston 1
306 Combustion ignition chamber 309 Compression chamber 310 Partition 311 Check valve 401, 407 Exhaust valve 402, 406 Supply valve 410, 411 Piston

Claims (2)

  Another combustion chamber (hereinafter referred to as “HCCI side combustion chamber”) connected to the combustion chamber provided with the ignition means (hereinafter referred to as “SI side combustion chamber”) is provided, and mechanically provided outside the connection portion. Gas in both combustion chambers is isolated by a free piston that is slidable in the cylinder without being connected to the cylinder, and the HCCI side combustion is performed by moving the free piston toward the HCCI side combustion chamber by plug ignition and expansion of the SI side combustion chamber An engine for compressing and igniting an air-fuel mixture in a chamber, wherein the pistons of both combustion chambers excluding the free piston are connected to each other by a mechanical mechanism.   A partition is provided between the piston and free piston of the SI side combustion chamber, an exhaust valve and ignition means are provided in the space between the free piston and the partition (hereinafter referred to as “combustion ignition chamber”), and the space between the partition and the piston ( (Hereinafter referred to as “compression chamber”) is provided with an intake valve, and a partition wall is provided with a hole connecting the combustion ignition chamber and the compression chamber. The valve opens when the compression chamber pressure is higher than the combustion ignition chamber pressure and closes when the pressure is low. The engine according to claim 1, further comprising:

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