JPH04279722A - Direct-injection impact-diffusion previous-reaction tyre combustion engine and its combustion method - Google Patents

Abstract

PURPOSE:To reduce the ignition delay of combustion by providing a thermoelectrode for ignition near the striking part of a fuel jet in a cylinder head, and making the combustion reaction after the intermediate period into a flame transmission and a diffusive self-ignition, while making the initial combustion reaction in a flame transmission. CONSTITUTION:Inside a combustion chamber cavity 2 to which the upper surface of a piston is faced, a fuel impact member 3 is provided. And near the fuel impact member 3, a glow plug 4 is provided. Furthermore, the fuel jet injected from an injection nozzle 6 attached to a cylinder head 5 is diffused into the periphery in a disk form by the strinking operation to the fuel impact member 3. In other words, following the striking diffusion of the fuel, a previous reaction area 7 is generated at the part of the glow plug 4, and it is developed rapidly by a flame transmitting function. And in the other fuel group diffused in a disk form, the flame transmission, the diffusion flame, and the self-ignition condition are developed, and thereby, the reaction of the following fuel group is expedited.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is based on a fuel supply method in which a fuel jet collides with the central region of a combustion chamber and spreads the fuel inside the combustion chamber by the collision diffusion effect, and a heat source is provided near the collision part. This invention relates to an internal combustion engine characterized by forming a pre-reaction zone in a part of the diffused fuel, and its combustion method.

0002

[Prior Art] Compression ignition engines that use a high compression ratio are energy efficient due to their high thermal efficiency, and are superior to gasoline engines in terms of CO2, CO, and HC emissions, but on the other hand, they produce large amounts of noise and vibration. Moreover, it has the disadvantage of producing a large amount of NOx and particulates.

The cause of these drawbacks is that there is a physical and chemical ignition delay between the supply of fuel and ignition, and the fuel supplied during this ignition delay period forms a premixture, which causes multiple This is due to the fact that the initial combustion rate is large because the reaction occurs almost simultaneously in several places. That is, the higher the initial combustion rate, the more rapidly the pressure within the combustion chamber increases and the temperature also increases. This sudden rise in pressure and temperature causes combustion noise and
Vibration will increase, and NOx will also increase. As a countermeasure to prevent this, retarding the injection timing to compression top dead center causes problems such as a decrease in thermal efficiency and an increase in smoke and particulates.These problems can be solved even in compression ignition engines, which have an advantage in thermal efficiency. Currently, the technology that can do this has not yet been developed.

0004

[Problems to be Solved by the Invention] In the conventional combustion method that uses a multi-hole nozzle to match the diffusion supply of fuel with air swirl flow, the spray flow energy from high-pressure injection collides with the wall surface, causing atomization and air flow. Reactions occur at each location where mixing has progressed, and the flame spreads mainly through the combustion process from near the wall toward the center area.Therefore, air flow (swirl) is used as a means to shorten the reaction period and improve air utilization.
Consistency is considered to be an essential condition. Further, in this case, the additional heat source such as a glow plug, which is effective, must be installed near the wall surface where the fuel spray reaches from one nozzle hole in the cavity. Therefore, even if a heat source is installed in this position, the effect of shortening the ignition delay and combustion period is small.

Another reason is that in the conventional direct injection system, the time required for the fuel group injected from the multi-hole nozzle to reach the wall surface is proportional to the distance, and the fuel is supplied into the combustion chamber from multiple injection holes. The fuel component is a multiplier for each nozzle hole, and when these react almost simultaneously at the collision location under certain conditions, a rapid rate of pressure rise occurs. For this reason, in conventional direct injection systems, even if a high-temperature heat source is installed inside the combustion chamber, it is difficult to expect improvements in ignition delay or rapid pressure rise rate associated with initial combustion unless the conventional injection conditions are changed. ing.

[0006]

[Means for Solving the Problems] In the present invention, by colliding the fuel jet from a single-hole nozzle near the nozzle hole, a radial flow is created to form a disc-shaped mixture group starting from the collision point. Efforts are being made to spread fuel. Therefore, the fuel density distribution within the combustion chamber is necessarily dense in the central region, and forms a stratified distribution pattern in which the fuel density becomes thinner in the outer regions. For this reason, the present invention is characterized in that swirl is not required for the air flow as a means for promoting diffusive combustion, and squish flow and moving flow are utilized due to the correlation between compression action and the shape of the combustion chamber.

[0007] In the present invention, compared to the conventional nozzle atomization system, the distance from the nozzle to the jet collision part is shortened, and the time required for attenuation of fuel flow energy due to collision action is shortened. Therefore, by arranging a high-temperature heat source near the center region in addition to this, it becomes possible to form a preliminary initial reaction region at a position near the center region of the combustion chamber. This forced ignition using a high-temperature heat source can shorten the ignition delay phenomenon and allow flame propagation from the center region and development of diffusive combustion to occur over a more average distance over the entire combustion chamber.

In this case, the flame spreads sequentially into the combustion chamber by the moving air flow from the squish region, and after top dead center, the reverse diffusion and mixing develops between the combustion chamber cavity and the squish region. As a result, injection lawful combustion with shortened ignition delay and combustion period is achieved.

In order to establish such conditions, first, a fuel collision part is arranged in the central region of the piston combustion chamber, a balanced fuel diffusion distribution pattern is created by the collision action of the fuel jets, and a fuel collision part protrudes into this cavity. A glow plug as a heat source that can be placed close to the nozzle is a requirement.

By increasing the glow plug temperature, a preliminary reaction zone is formed in response to the fuel reaching a part of the central region of the combustion chamber without depending on the compression effect. That is, of the collision-diffusion fuel group developed in a disk shape, the portion of the fuel that comes into contact with the glow plug is rapidly activated, and a reaction is generated in this region before other regions.

The present invention forcibly and proactively causes a part of the fuel to react in the early stage of fuel supply in the central region of the combustion chamber, increases the temperature and pressure in the combustion chamber through the preliminary flame propagation combustion reaction, and controls the initial combustion rate. It is something to do. Further, due to the ignition delay phenomenon, the fuel supplied into the combustion chamber simultaneously reacts in large quantities, thereby controlling the high rate of pressure rise that occurs. Therefore, the subsequent fuel group is supplied into an atmosphere where the temperature and pressure are sufficiently increased due to the preceding reaction, and the combustion reaction, which includes flame propagation and self-ignition diffusion combustion, proceeds sequentially and rapidly, and the combustion period This results in shorter and quieter operation.

0010

[Embodiment] An embodiment of the present invention will be explained with reference to the drawings. A fuel collision part (3) is configured inside the piston (1) cavity (2), and a glow plug (4) is located near the collision part (3).
is located. As shown in Figure 1, the fuel jet from the injection nozzle (6) attached to the cylinder head (5) is diffused into a disc shape around the circumference due to the collision effect, and of this, 360 ml of fuel jet reaches the glow plug (4). This is within the range of 〈θ in the range of 〈θ〉, and the diffusion rate of the arriving fuel is also suppressed by the collision effect, so the glow plug is not worn out by the contact effect, and since the amount is small, the plug temperature can be controlled by heat exchange. There is little deterioration, therefore, the factors that impair the durability of the glow plug are reduced.

[0011] As described above, the fuel that reaches or approaches the glow plug heat source section, which is maintained at a temperature corresponding to the ignitability of the supplied fuel, immediately starts to react.

[0012] That is, due to fuel collision and diffusion, a pre-emptive reaction region (7) is formed in the glow plug region earlier than in other regions. This pre-reaction zone is small at first but rapidly develops due to flame propagation effects. The temperature and pressure within the combustion chamber inevitably rise as the advance reaction zone is formed and expanded. Therefore, the flame propagation, diffusion flame, and self-ignition conditions of the other fuel groups diffusing in a disk shape also progress as the ambient temperature and pressure rise, and the reactions of the subsequent fuel groups are promoted.

Such a reaction process is a particularly effective means in the method of the present invention in which the fuel group diffuses in the central region of the combustion chamber. Methods in which the reactions are started simultaneously are less effective.

The examples were conducted using methanol (99.9%), which is considered to be less ignitable than diesel fuel with a high cetane number.

[Table 1] Indicates the specifications of the test engine

[0015]

Effects of the Invention: Immediately after fuel supply, the combustion method of the present invention forcibly and reliably constructs a local reaction zone in a part of the diffused fuel group in advance compared to the entire fuel supply period, compared to conventional compression ignition combustion. Unlike the conventional method, it is possible to distribute the combustion rate over the entire combustion period close to the injection law. Therefore, the heat generation pattern can be freely changed by controlling the injection system.

[0016] As a result, it has become possible to shorten the ignition delay phenomenon, which has traditionally been considered a drawback of high thermal efficiency compression ignition internal combustion engines, and to use many combustible substances and alternative fuels that were considered difficult to combust ignite. .

[0017] Since it has become possible to control the combustion rate by shortening the ignition delay period and forming a pre-reaction zone, combustion with the initial combustion rate suppressed greatly reduces the diesel knock phenomenon caused by the initial pressure rise rate, and further improves combustion. Since it is possible to freely control the maximum pressure, heat release rate, combustion period, etc., many features and effects have been demonstrated as shown below.

1. Combustion noise and NOx were reduced by reducing the rapid initial combustion pressure rise rate. 1. By setting the combustion ratio to the injection law, the heat release rate was idealized, the maximum combustion pressure was suppressed, high thermal efficiency was obtained, and CO2 and NOx were reduced. 1. The synergistic effect of shortening the combustion period according to injection rules and suppressing the rate of pressure rise maintains high thermal efficiency, achieves a quiet engine, and improves durability and reliability. 1. Stratified diffusion combustion centered on forced heat source ignition reduces unburned components in the exhaust gas. 1. Since no air swirl is required, the intake system resistance is low, and the specific output is improved by improving the volume ratio. 1. The pressure of the injection system does not need to be extremely high, and the use of a single hole nozzle is advantageous in terms of reliability and durability. 1. Longer plug life due to lower proportion of fuel reaching the glow plug and less impact energy. 1. Productivity is easy because there is no need to use ultra-high pressure, and there is no need to invest in equipment for this purpose, resulting in a reduction in production costs. 1. It is effective when applied to both 2-cycle and 4-cycle formulas.

[0019] The injection nozzle of the present invention has a single hole and a large nozzle hole area, which makes it possible to use pulverized fuel and gaseous fuel other than liquid fuel, which is considered to be the limit of conventional multi-nozzle systems. It will also be easier to design small direct injection engines, etc.
It has many effects and features.

[Brief explanation of the drawing]

The drawings illustrate the structure and operation of the present invention.

[Figure 1] Cross-sectional view near the center of the combustion chamber

[Figure 2] Example of configuration when the injection nozzle is tilted

[Figure 3]
Net thermal efficiency map of the test engine according to the present invention

[Figure 4] CO
concentration map

[Figure 5] Unburnt methanol concentration map

[Figure 6] NOx concentration map

[Figure 7] In-cylinder pressure and heat release rate waveform in each load range at 2500 rpm

[Figure 8] Cylinder pressure in each load range at 2500 rpm
Indicates heat release rate and pressure rise rate

[Figure 9] A diagram showing the influence of load at 2500 rpm, with the dotted line representing the range of intake throttle action.

[Explanation of symbols]

1 Piston 2 Combustion chamber cavity 3 Collision section 4 Electric heat source plug 5 Cylinder head section 6 Fuel nozzle 7 Preliminary reaction zone 8 Direction of air flow due to squish 9 Collision section support 10 Initial diffusion fuel group

Claims (5)

[Claims] Claim 1: An internal combustion engine having a structure in which a cylinder head part supports a fuel injection nozzle and a collision part for diffusing the fuel jet of the injection nozzle by collision action, in which a heating electrode for ignition is provided near the collision part. , the starting condition for the initial combustion reaction is flame propagation combustion due to a part of the diffused fuel coming into contact with the heating electrode, and the combustion reaction after the middle stage is characterized by a combustion method in which flame propagation and diffusive self-ignition are mixed. Hot surface ignition combustion method. 2. The cylinder head has a fuel injection nozzle and a fuel collision part for diffusing the fuel jet from the nozzle by jet collision action, and the collision part is electrically heated to evaporate and vaporize the supplied fuel. A direct-injection internal combustion engine that has enhanced accelerating action and is further characterized by the installation of a heating electrode for ignition near the collision area. 3. A thermal ignition electrode is provided near the collision part, and a combustion reaction region is formed in the vicinity of the ignition electrode prior to other regions by forming a fuel collision diffusion pattern and matching the injection timing. An internal combustion engine pre-ignition combustion method according to claim 1 of the previous patent. 4. The collision surface of the fuel jet collision part has a protrusion for enhancing the dispersion of the jet, the shape of the protrusion is conical or polygonal pyramid, and the apex of the cone is located at the center of the fuel jet. The internal combustion engine according to claim 1, characterized in that the combustion chamber is arranged in such a manner that the internal combustion engine has a combustion chamber configuration. 5. The internal combustion engine according to claim 1, wherein an electric heating device is built in the fuel collision part, and the temperature of the collision part is controlled by electrical control.