JPH09317471A - Diesel engine using low quality fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diesel engine, using low quality fuel, to improve fluidity of air and fuel by injecting low quality fuel, such as heavy oil, in a cylinder at the initial stage of a compression stroke and suppress the generation of NOx by generating uniform air-fuel mixture. SOLUTION: In a diesel engine, an auxiliary combustion chamber 2 is formed in a piston 5 and a main combustion chamber 1 consists of a combustion chamber structure 3 arranged in the cavity 9 of a cylinder head 7. A plurality of communication holes 15 radially formed and a fuel injection hole 13 in the shape of a flux are formed in the piston 5. Low quality fuel, such as heavy oil, is injected in a cylinder 8 through a fuel injection nozzle 6 at the initial stage of a compression stroke. The fuel is dispersed in a swirl present in the cylinder 8, uniform air-fuel mixture of fuel and air is generated in the cylinder 8, and fuel for ignition is reliably fed through the fuel injection nozzle 13 in the auxiliary combustion chamber 2 at the terminal stage of the compression stroke and ignited for combustion in the auxiliary combustion chamber 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine using a low quality fuel, which is applied to a cogeneration engine having a sub combustion chamber in a piston.

[0002]

2. Description of the Related Art In general, gasoline, light oil and heavy oil are used as fuels used in engines. Conventionally, in a diesel engine, light oil is burned in a combustion chamber as fuel. In addition, the cetane number of the fuel is as small as about 25 for heavy oil while that for light oil is 40 or more. In terms of fuel vaporization, gasoline is large, light oil is small,
Heavy oil has almost no volatility. Regarding the fuel price, for example, if gasoline is 100, light oil is 7
It is about 0 and heavy oil is about 15.

Conventionally, there have been many systems in which a generator is attached to an engine as a power generation device including a cogeneration engine. However, in power generation by a diesel engine, the diesel engine uses light oil as fuel, resulting in a high fuel cost, and a power company. The cost will be higher than the electric power supplied from, and there is a problem that it is not possible to secure superiority in terms of equipment depreciation. To get electricity from a gasoline engine, the cost is too high,
I can not cope. A cogeneration engine uses natural gas as a fuel because the fuel cost becomes high when gasoline or light oil is used as a fuel.

The present inventor has developed a diesel engine using fuel oil as a fuel and previously applied for it as Japanese Patent Application No. 8-46956. The diesel engine can ignite and burn heavy oil that has a high viscosity and is not vaporizable as a fuel without high-pressure injection, provides a main chamber and a sub chamber in the cylinder head, and injects fuel near the communication port. A fuel injection nozzle is provided, and immediately after the on-off valve provided at the communication port is opened, fuel is injected from the fuel injection nozzle toward the seat of the on-off valve, and the fuel is placed on the high-speed air flow passing through the communication port.
The fuel is dispersed in the air flow from the main chamber to the sub chamber, vaporized and dispersed, and then ignited and burned.

[0005]

The engine used for the cogeneration engine and the power generation system must have high thermal efficiency and clean exhaust gas. Many. However, light oil is often used as fuel for vehicles such as vehicles, and the supply-demand relationship for light oil is not necessarily good. Further, although a conventional cogeneration engine using natural gas is used, even with natural gas, the fuel cost is still high, and it is difficult to obtain the supply of natural gas in some regions. Therefore, it is desired to develop a diesel engine that uses a low-vaporization fuel such as heavy oil as a fuel without using light oil or natural gas as a fuel, but uses a low-vaporization fuel such as heavy oil as a fuel. Soot and NO _x when used
There are various problems such as the occurrence of fuel, and it is necessary to develop a fuel system that solves them by using a low vaporization fuel such as heavy oil as a fuel.

Further, in a diesel engine that uses low-quality fuel such as heavy oil as fuel, if the fuel is injected into the high temperature atmosphere in the combustion chamber of the heat shield structure, the air and fuel are not sufficiently mixed, resulting in a non-uniform mixture. As a result, a non-uniform flame is formed in the outer peripheral region of the fuel spray to form a local high temperature region, and NO _X
Occurs in large quantities. Further, in a diesel engine that uses a low-vaporizing fuel such as heavy oil as a fuel, the viscosity of the fuel is large, so an injection pump that requires high compression cannot be used, and it is difficult to create fuel spray at high pressure in the combustion chamber. Moreover, there is a problem that the mixing of air and fuel is deteriorated and a large amount of HC, soot, etc. are generated. In the case of heavy oil having a large viscosity, it is necessary to enlarge the fuel injection pump in order to increase the pressure of the heavy oil, but if a fuel injection pump with a large oil feed amount is used, it becomes an expensive pump.

In a low-speed marine diesel engine, the number of revolutions is sufficiently slow as 100 to 200 rpm or less, so that the mixing time of air and fuel is sufficient, and the high pressure spray is radially generated from the fuel injection nozzle to the periphery of the cylinder. When the fuel is generated and burned in a uniform mixture, the fuel consumption can be improved, but there is a problem that NO _X and smoke are often generated.

However, the diesel engine speed operation such as cogeneration engine, air and fuel mixed without time is short enough, the or occurred ignition miss intact, the generation of the NO _X and smoke increases, In view of this point, there is a problem of how to generate a favorable and uniform air-fuel mixture and burn it favorably to improve fuel efficiency, and particularly to reduce the generation of NO _X and smoke.

In order to improve the combustion, improve the thermal efficiency and purify the exhaust gas, it is necessary that the combustion period is short and the fuel and air are well mixed. In a diesel engine, when a heat-resistant material such as ceramics is used as a structural material of a combustion chamber, the temperature in the combustion chamber rises to 250 ° C. or more at the compression end, and a high-temperature atmosphere is created. When a low-vaporizing fuel such as heavy oil is injected into such a high-temperature atmosphere in a diesel engine, the air and fuel are not sufficiently mixed, and a non-uniform flame in the outer peripheral area of the fuel spray creates a localized high-temperature area. Therefore, there is a problem that a large amount of NO _X is generated. In diesel engines, N
O _X, to reduce the occurrence of soot, but want to lean air-fuel mixture, there is a problem that misfire occurs when the lean air-fuel mixture.

In a high speed diesel engine using a low quality fuel such as heavy oil, it is difficult to mix the fuel and air,
Performance is low, NO _X, contains harmful substances such as soot in the exhaust gas. In order to improve the performance and improve the mixing of fuel and air, it is necessary to effectively contact the fuel and air, but as a method of effectively mixing and burning low-quality fuel such as heavy oil with air. It is considered that the mixing time of the fuel and air is lengthened, the temperature of the air is increased, and the kinetic energy of the air is used to promote the mixing of the air and the fuel. By the way, in an engine in which the combustion chamber has a heat shield structure, the intake air receives heat from the wall surface of the combustion chamber and is heated, so that the vaporization property of the fuel is excellent. Therefore, if the combustion chamber has a heat shield structure and the fluidity of air and fuel in the combustion chamber is improved, low-quality fuel such as heavy oil can be satisfactorily combusted. Further, NO _X is a harmful substance in the exhaust gas, when the particulate fuel to burn in air tends to large amount of generated reacts with air surrounding the particles. However, when the combustion reaction occurs in a state where the fuel is dispersed in the air, the combustion is controlled by the temperature of the air outside the fuel, the temperature does not rise so much, and the generation of NO _X is suppressed.

[0011]

SUMMARY OF THE INVENTION In consideration of the above, an object of the present invention is to introduce a heat-resistant material such as ceramics as a structural material of the combustion chamber into the heat-shielding structure of the combustion chamber and to introduce the same into the combustion chamber. To increase the temperature of the intake air, allow sufficient time for the fuel and air to mix, and utilize the air flow,
A low-vaporizing fuel such as heavy oil, that is, a low-quality fuel is injected at a wide angle into the intake swirl in the region where the piston is on the bottom dead center side and the air pressure is small, and the wide-angle injected fuel is dispersed in the air flow in the cylinder to promote mixing. To produce a lean mixture,
As the piston rises, the air-fuel mixture flows into the auxiliary combustion chamber located in the center through the communication hole at a high speed to promote mixing and generate a uniform air-fuel mixture in the auxiliary combustion chamber. The low-quality fuel for ignition is injected through the fuel injection hole of the NOx so as to collect, and a rich air-fuel mixture which is easily ignited is generated in the auxiliary combustion chamber to be ignited and burned to generate NO _X.
It is an object of the present invention to provide a diesel engine that uses a low-quality fuel that suppresses the generation of smoke and smoke.

According to the present invention, a cylinder head fixed to a cylinder block constituting a cylinder, a combustion chamber structure constituting a main combustion chamber of a heat shield structure provided in a cavity formed in the cylinder head, and the cylinder head are formed. A suction / exhaust valve for opening / closing an exhaust port, a piston in which a sub-combustion chamber having a heat shield structure reciprocating in the cylinder is formed, and the main combustion chamber formed in the piston and the sub-combustion chamber communicate with each other. A plurality of communication holes spaced in the circumferential direction, a fuel injection hole formed in a substantially central portion of the piston such that the passage cross-sectional area decreases from the piston top surface toward the auxiliary combustion chamber, and in the cylinder head. Low-quality fuel is injected into the arranged cylinder in a diffused state in the first half of the compression stroke, and is ignited into the auxiliary combustion chamber through the fuel injection hole in the second half of the compression stroke. A fuel injection nozzle for injecting fuel-,
The present invention relates to a diesel engine using a low quality fuel composed of

Further, on the wall surface of the fuel injection hole, Pt,
An ignition promoting catalyst layer of Ni, Cs or the like is arranged. Therefore, the fuel injected from the fuel injection nozzle through the fuel injection hole into the sub-combustion chamber mixes with the lean air-fuel mixture having a high temperature to generate a rich air-fuel mixture which is easy to ignite, and further, the ignition. It is possible to reliably ignite even when the temperature is low by coming into contact with the promoted catalyst layer.

The intake air introduced into the cylinder from the intake port forms a swirl in the cylinder.

Further, the fuel spray, in which 50% or more of the total injected fuel is injected from the fuel injection nozzle at the beginning of the compression stroke, is diffused and injected into the cylinder from the cylinder center to the periphery of the piston top surface, and is compressed. The remaining fuel spray for ignition injected near the end of the stroke is collected in the fuel injection hole, receives heat from the wall surface of the fuel injection hole, and is injected into the auxiliary combustion chamber.

Further, the diesel engine using this low quality fuel is applied to a stationary cogeneration engine. That is, in a stationary cogeneration engine, the engine rotation and load are almost constant,
It is easy to set the fuel injection timing to the main combustion chamber to be constant, and in particular, the generation of NO _X can be suppressed, and since a low vaporizing fuel such as heavy oil can be used as the fuel, fuel consumption can be reduced.

As described above, the diesel engine using this low-quality fuel injects the low-quality fuel in a diffused state from the fuel injection nozzle into the cylinder, and then, from the top surface of the piston to the sub-combustion chamber, at approximately the center of the piston. The low-quality fuel for ignition is injected into the sub-combustion chamber through the fuel injection hole whose passage cross-sectional area becomes smaller, and is ignited and burned in the sub-combustion chamber. At the same time, the air-fuel mixture enters the sub-combustion chamber through the communication hole and the fuel injection hole, promotes mixing in the sub-combustion chamber, and near the end of the compression stroke, the low-quality fuel for ignition is passed from the fuel injection nozzle through the fuel injection hole to the sub-combustion chamber. Is injected into the cylinder to ignite and burn, and NO
_{The amount of X} is small and ideal combustion can be performed. Further, in this diesel engine, since the fuel spray from the fuel injection nozzle is conically diffused and injected from the center of the cylinder toward the periphery of the cylinder in the first half of the compression stroke, the low-quality fuel is well dispersed in the air in the cylinder. , A uniform air-fuel mixture is generated in the cylinder.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a diesel engine using a low quality fuel according to the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing a state of a piston top dead center, which is an embodiment of a diesel engine using a low quality fuel according to the present invention, and FIG. 2 is a plan view showing an upper surface of the piston.
3 and FIG. 3 are cross-sectional views showing a state near the piston bottom dead center of the diesel engine using the low quality fuel of FIG.

The diesel engine of this embodiment is a combustion system capable of using a low vaporizing fuel such as heavy oil, that is, a low quality fuel. For example, the diesel engine is a preferable engine to be applied to a stationary cogeneration engine. It is operated by sequentially repeating four strokes, an expansion stroke and an exhaust stroke.

In this diesel engine, a cylinder head 7 is fixed to an upper portion of a cylinder block 14 through a gasket 23, and a cavity 9 formed in the cylinder head 7 constitutes a main combustion chamber 1 having a heat shield structure. Three
Is arranged. This diesel engine has a cylinder liner 32 and a cylinder liner 32 that form a cylinder 8 fitted in a hole 33 formed in the cylinder block 14.
And a piston 5 that reciprocates in a cylinder 8 formed by the combustion chamber structure 3. In the cylinder head 7,
A fuel injection nozzle 6 that injects fuel into the main combustion chamber 1 is arranged. In the combustion chamber structure 3, an expanded through hole 4 is formed substantially on the central axis of the main combustion chamber 1.

The piston 5 comprises a piston head 16 made of ceramics such as silicon nitride having excellent heat resistance to form the combustion chamber 1 having a heat shield structure together with the combustion chamber structure 3.
It is composed of a piston skirt 17 which is fixed to the piston head 16 with a coupling ring 24 by metal flow. The piston head 16 has a cavity 19 that forms the auxiliary combustion chamber 2. Piston head 16
Is a communication hole 1 that connects the main combustion chamber 1 and the auxiliary combustion chamber 2 to each other.
5, and a fuel injection hole 13 through which fuel can be injected into the auxiliary combustion chamber 2 is formed substantially at the center of the piston 5. As shown in FIG. 2, a plurality of communication holes 15 (eight in FIG. 2) are formed on the piston top surface 18 of the piston head 16 so as to be spaced apart in the circumferential direction and open. The fuel injection hole 13 is
From the piston upper surface 18 of the piston head 16 to the auxiliary combustion chamber 2
It is formed in a converging shape with a curved surface or a tapered surface so that the cross-sectional area of the passage becomes smaller toward.

In this diesel engine, the combustion chamber structure 3 has a liner upper portion 1 which constitutes a part of a cylinder 8.
2 is a head liner including a head lower surface portion 11. The lower surface 11 of the head has intake and exhaust ports 22.
(Only the intake port is shown) is formed. The intake port 22 communicates with an intake port 25 formed in the cylinder head 7, and although not shown, the exhaust port formed in the head lower surface portion 11 communicates with the exhaust port formed in the cylinder head 7. Intake valve 2 in intake port 22
1 is arranged, and an exhaust valve is arranged at the exhaust port. Between the cavity 9 of the cylinder head 7 and the outer surface of the combustion chamber structure 3, a gasket 30 is interposed and a heat shield air layer 26 is formed, so that the combustion chamber 1 has a heat shield structure. Further, a gasket 31 is interposed between the piston head 16 and the piston skirt 17, a heat shield air layer 27 is formed between the piston head 16 and the piston skirt 17, and a cavity 19 formed in the piston head 16 is formed. The sub-combustion chamber 2 composed of is constructed in a heat shield structure. The gaskets 30 and 31 can function as a seal and a heat shield.

In this diesel engine, the fuel injection nozzle 6 injects low-quality fuel such as heavy oil into the cylinder 8 and also injects ignition fuel into the auxiliary combustion chamber 2 through the fuel injection hole 13 so as to inject the fuel. It is provided in. In this diesel engine, the combustion chamber structure 3, which is the wall forming the main combustion chamber 1, the cylinder liner 32, and the piston head 16 are made of ceramics such as silicon nitride and silicon carbide having excellent heat resistance. Therefore,
Each component has sufficient heat resistance and high-temperature strength even if the gas temperature in the latter stage of combustion becomes high, and the emission of unburned hydrocarbons and the like is reduced, so that a highly efficient engine can be configured.

In the diesel engine using this low-quality fuel, the fuel injection nozzle 6 is formed, for example, as a single injection port, and the low-quality fuel is conically diffused and injected into the cylinder 8 toward the entire area of the piston top surface 18. Therefore, the low-quality fuel for ignition injected from the fuel injection nozzle 6 can be smoothly injected through the fuel injection hole 13,
A fuel injection hole 13 is formed in a substantially central portion of the piston 5 in a curved surface or a tapered surface so that the passage cross-sectional area decreases from the piston top surface 18 toward the auxiliary combustion chamber 2. Therefore, 50% of all injected fuel is injected from the fuel injection nozzle 6 at the beginning of the compression stroke.
The fuel spray F from which the above fuel is injected is diffused and injected into the cylinder 8 from the center of the cylinder to the periphery of the piston top surface 18, and then the remaining fuel spray for ignition injected near the end of the compression stroke is the fuel injection. The fuel is collected in the inlet holes 13 and receives heat from the wall surface of the fuel injection holes 13 and is injected into the auxiliary combustion chamber 2.

In this diesel engine of low vaporization fuel, as shown in FIG. 3, the intake air introduced into the cylinder 8 from the intake ports 22 and 25 by opening the intake valve 21 is in the cylinder 8 in the above structure. At a swirl or air flow S. Therefore,
In the first half of the compression stroke after the suction stroke is completed, the fuel spray F from the fuel injection nozzle 6 is the air flow S in the cylinder 8.
During the compression stroke, the fuel spray F from the fuel injection nozzle 6 is widely diffused in a conical shape from the vicinity of the piston bottom dead center at the beginning of the compression stroke, and is injected so that the low-quality fuel is dispersed in the air flow S. The piston 5 rises, the air in the cylinder is compressed and the temperature rises, the vaporization of the fuel is promoted, the fuel is dispersed almost uniformly during the air flow, and the air-fuel mixture is generated. A homogeneous mixture is produced. As the piston 5 moves upward in the compression stroke, the air-fuel mixture in the cylinder 8 enters the sub-combustion chamber 2 through the communication hole 15 and the fuel injection hole 13 to promote mixing in the sub-combustion chamber 2.

Next, at the end of the compression stroke, ignition fuel is injected from the fuel injection nozzle 6 through the fuel injection hole 13 to ignite and burn in the auxiliary combustion chamber 2. This time,
As shown in FIG. 1, the fuel injected from the fuel injection nozzle 6 is once diffused, but immediately gathers through the converging passage of the fuel injection hole 13 and receives heat from the wall surface so that the inside of the auxiliary combustion chamber 2 is received. Is injected into the air, and a rich mixture suitable for ignition is formed and the material is ignited and burned. The flame is propagated to the homogeneous mixture in the sub combustion chamber 2 and burns at once. Then, in the expansion stroke, the flame is ejected from the sub-combustion chamber 2 toward the periphery of the cylinder of the main combustion chamber 1 through the communication hole 15, and the lean air-fuel mixture in the main combustion chamber 1 is burned at once, and the secondary combustion is performed in a short time. It is completed and suppresses the generation of soot and NO _x and improves the thermal efficiency.

Next, another embodiment of the diesel engine using the low quality fuel according to the present invention will be described with reference to FIG. This embodiment is different from the above embodiment in that the piston 5
Since the fuel injection hole 13 formed in 1 has the same configuration and the same action except that the configuration is different, the same reference numerals are given to the same components, and duplicate description will be omitted. An ignition promoting catalyst layer 10 of platinum (Pt), nickel (Ni), cesium (Cs), or the like is arranged on the wall surface of the fuel injection hole 13 formed in the piston 5. Therefore, the low-quality fuel supplied to the sub-combustion chamber 2 in contact with the ignition promoting catalyst layer 10 on the wall surface of the fuel injection hole 13 is activated and easily ignites even at a low temperature such as partial load. It can be ignited and burned to prevent misfire.

[0028]

Since the diesel engine using the low-quality fuel according to the present invention is configured as described above, at the stage where the pressure in the cylinder is low in the first half of the compression stroke, the diesel engine has a conical shape from the cylinder center side to the cylinder periphery. By spraying low-quality fuel such as heavy oil over a wide area into the air flow in the cylinder toward the entire top surface of the piston, low-vaporizing fuel such as heavy oil is uniformly dispersed and dispersed in the main combustion chamber. It is possible to generate a uniform mixture of fuel and air in the main combustion chamber, and then, in the compression stroke, enter the auxiliary combustion chamber from the main combustion chamber through the communication hole and the fuel injection hole, and further in the auxiliary combustion chamber. In the vicinity of the end of the compression stroke, the fuel for ignition is injected from the fuel injection nozzle into the auxiliary combustion chamber through the fuel injection hole, and is surely ignited and combusted to suppress NO _X generation and burn. Next, in the expansion stroke, since a uniform air-fuel mixture has already been generated in the main combustion chamber, the flame that is uniformly dispersed and ejected from the sub-combustion chamber to the main combustion chamber in the circumferential direction becomes a fire species and becomes the main combustion chamber. Does not generate a non-uniform flame, the combustion propagation in the main combustion chamber becomes faster, and therefore, a non-uniform flame on the outer periphery of the fuel spray does not generate a local high temperature region, and the air-fuel mixture burns at a high temperature. generation of the nO _X from no is suppressed, to complete the combustion in short.

As described above, the low-vaporization fuel diesel engine can operate at high speed even though it uses a low-vaporization fuel such as an inexpensive heavy oil, that is, a low-quality fuel, as a fuel. The generation of _X is suppressed, the exhaust gas is clean, and the thermal efficiency with excellent ignitability is improved. Therefore, it is extremely preferable when applied to a cogeneration engine used in a power generation system.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state of a piston top dead center in an embodiment of a low vaporization fuel diesel engine according to the present invention.

2 is a plan view showing an upper surface of a piston in the low-vaporization fuel diesel engine of FIG. 1. FIG.

FIG. 3 is a cross-sectional view showing a state near a piston bottom dead center of the diesel engine of the low vaporization fuel of FIG.

FIG. 4 is a cross-sectional view showing another embodiment of the low-vaporizing fuel diesel engine according to the present invention and showing the state of the piston top dead center.

[Explanation of symbols]

 1 Main Combustion Chamber 2 Sub Combustion Chamber 3 Combustion Chamber Structure 5 Piston 6 Fuel Injection Nozzle 7 Cylinder Head 8 Cylinder 9, 19 Cavity 10 Ignition Accelerating Catalyst Layer 13 Fuel Injection Hole 14 Cylinder Block 15 Communication Hole 21 Intake Valve 22, 25 Intake port

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location F02B 23/06 F02B 23/06 N F02F 1/24 F02F 1/24 DC C 3/26 3/26 A F02M 37 / 00 341 F02M 37/00 341A

Claims (5)

[Claims] 1. A cylinder head fixed to a cylinder block constituting a cylinder, a combustion chamber structure constituting a main combustion chamber of a heat shield structure provided in a cavity formed in the cylinder head, and an intake member formed in the cylinder head. An intake valve that opens and closes an exhaust port, an exhaust valve, a piston that forms a sub-combustion chamber having a heat-shielding structure that reciprocates in the cylinder, and the main combustion chamber and the sub-combustion chamber are separated from each other in the circumferential direction. A plurality of communication holes formed in the piston, a fuel injection hole formed in a substantially central portion of the piston so as to have a passage cross-sectional area decreasing from the piston top surface toward the auxiliary combustion chamber, and arranged in the cylinder head Injecting low-quality fuel into the cylinder in a diffused state in the first half of the compression stroke,
A diesel engine using a low-quality fuel, comprising a fuel injection nozzle for injecting a low-quality fuel for ignition into the auxiliary combustion chamber through the fuel injection hole in the latter half of the compression stroke. 2. The wall surface of the fuel injection hole has Pt, Ni,
The diesel engine using the low quality fuel according to claim 1, wherein an ignition promoting catalyst layer of Cs is arranged. 3. The diesel engine using low-quality fuel according to claim 1, wherein the intake air introduced into the cylinder from the intake port forms a swirl in the cylinder. 4. The fuel spray in which 50% or more of the total injected fuel is injected from the fuel injection nozzle at the beginning of the compression stroke is diffused and injected from the center of the cylinder to the periphery of the top surface of the piston and compressed. The remaining fuel spray for ignition injected near the end of the stroke is collected in the fuel injection hole, receives heat from the wall surface of the fuel injection hole, and is injected into the auxiliary combustion chamber. A diesel engine using the low-quality fuel according to any one of items. 5. The diesel engine using the low-quality fuel according to claim 1, which is applied to a stationary cogeneration engine.