CN119467124A - Engine piston, engine and engine control method - Google Patents
Engine piston, engine and engine control method Download PDFInfo
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- CN119467124A CN119467124A CN202510045813.0A CN202510045813A CN119467124A CN 119467124 A CN119467124 A CN 119467124A CN 202510045813 A CN202510045813 A CN 202510045813A CN 119467124 A CN119467124 A CN 119467124A
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Abstract
The invention belongs to the technical field of engines, and discloses an engine piston, an engine and an engine control method. The engine piston comprises a piston body, a central boss and a first annular boss are arranged at the top of the piston body, a lower combustion pit is formed between the central boss and the first annular boss, an upper combustion pit is formed on the outer periphery side of the first annular boss on the piston body, and a second annular boss is arranged on the side wall of the central boss in a protruding mode. The distance between the highest point of the first annular bulge and the lowest point of the lower combustion pit is a first distance h1 along the axial direction of the piston body, the distance between the first contour line and the lowest point of the lower combustion pit is a first distance h1, the distance between the bulge vertex of the second annular bulge and the lowest point of the lower combustion pit is a second distance h2, and h2 is smaller than h1. The engine can effectively improve the loading capacity of the engine when running under low load, and can effectively reduce the deterioration of the engine performance when running under high load.
Description
Technical Field
The invention relates to the technical field of diesel engines, in particular to an engine piston, an engine and an engine control method.
Background
The diesel generator set mainly comprises a diesel engine, a generator and the like, wherein the diesel engine is in transmission connection with the generator, the diesel engine converts heat energy generated by diesel combustion into mechanical energy to drive the generator to operate, the generator converts the mechanical energy into electric energy, a turbocharger is integrated on the diesel engine, tail exhaust gas of the diesel engine is introduced into the turbocharger to drive the turbocharger to operate, and the turbocharger is enabled to press air into a diesel engine cylinder body.
When the transient state is suddenly added, diesel oil can be instantaneously sprayed into the cylinder, but the turbocharger has hysteresis, and especially under the working conditions of starting and low-load operation of the diesel engine, the air inflow can be greatly delayed from the fuel inflow, so that the improvement of the transient state capability of the diesel engine is influenced, and how to improve the air utilization rate and the mixed combustion effect under the limited air condition, thereby improving the working capacity is one of the keys of the improvement of the transient state capability of the diesel engine.
At present, in the prior art, the purposes of improving the air utilization rate and improving the mixed combustion effect are generally achieved by adjusting the structural characteristics and/or specific spraying combustion methods of a combustion chamber of a diesel engine. Secondly, the diesel engine has less fuel injection quantity under the low-load operation condition and more fuel injection quantity under the high-load operation condition, so that the air utilization rate and the mixed combustion effect of the diesel engine under the low-load operation condition are optimized, and the performance of the diesel engine is often deteriorated under the high-load operation condition.
Disclosure of Invention
The present invention is directed to an engine piston, an engine and an engine control method, which solve the above problems in the prior art.
To achieve the purpose, the invention adopts the following technical scheme:
the engine piston comprises a piston body, wherein the top of the piston body is provided with a central boss and a first annular bulge, a lower combustion pit is formed between the central boss and the first annular bulge, and an upper combustion pit is formed on the outer periphery side of the first annular bulge on the piston body;
the side wall of the central boss is convexly provided with a second annular bulge;
The distance between the highest point of the first annular bulge and the lowest point of the lower combustion pit is a first distance h1 along the axial direction of the piston body, the distance between the first contour line and the lowest point of the lower combustion pit is a first distance h1, the first contour line is a connecting contour line far away from the lowest point of the lower combustion pit in the connecting contour lines of the second annular bulge and the central boss, the distance between the bulge vertex of the second annular bulge and the lowest point of the lower combustion pit is a second distance h2, and h2 is smaller than h1.
As a preferable scheme of the engine piston, when the piston body is positioned at the top dead center, a combustion chamber is formed between an engine cylinder cover and the top of the piston body, the distance from the top of the combustion chamber to the lowest point of the lower combustion pit along the axial direction of the piston body is the height h of the combustion chamber, and h1= (0.43-0.5) h.
As a preferable mode of the engine piston, the diameter of the piston body is D;
the diameter d1= (0.2-0.25) D of the first contour line;
and the diameter D2= (0.3-0.35) D of a second contour line, wherein the second contour line is a connecting contour line which is close to the lowest point of the lower combustion pit in the connecting contour lines of the second annular bulge and the central boss.
As a preferable mode of the engine piston, the diameter of the piston body is D;
along the radial direction of the piston body, the diameter d3= (0.45-0.6) D corresponding to the furthest end of the lower combustion pit far away from the central axis of the piston body.
As a preferable mode of the engine piston, a groove is arranged at the top of the piston body, the groove is positioned at the outer periphery side of the first annular bulge, and the groove forms the upper combustion pit;
The interval between the lowest point of the upper combustion pit and the lowest point of the lower combustion pit is a fourth interval h4, h4< h1 along the axial direction of the piston body, and the included angle between the connecting line between the lowest point of the upper combustion pit and the highest point of the first annular bulge and the plane vertical to the axial direction of the piston body is alpha, 0 degrees < alpha <15 degrees.
As a preferable mode of the engine piston, the diameter of the piston body is D;
along the radial direction of the piston body, the diameter D4= (0.76-0.83) D corresponding to the furthest end of the upper combustion pit far away from the central axis of the piston body.
The engine comprises a cylinder cover, an engine cylinder body, an oil injector, the engine piston, a piston body, a combustion chamber, the oil injector and the engine cylinder, wherein a cylinder chamber is formed between the cylinder cover and the engine cylinder body;
And when the piston body is positioned at the top dead center along the axial direction of the piston body, the distance between the collision wall point of the central oil beam, which is shot into the collision wall of the lower combustion pit, and the lowest point of the lower combustion pit is a third distance h3, wherein h3 is smaller than h2.
As a preferable embodiment of the engine, h3= (0.7 to 0.8) h1.
An engine control method for implementing the engine, the engine control method comprising:
when the engine runs under low load, determining whether the internal combustion oil can be completely injected in a preset oil injection duration according to the total oil injection quantity and the current rail pressure;
If the fuel oil can be completely injected within the preset oil injection duration, injecting oil into the combustion chamber according to a preset oil injection starting crank angle and the preset oil injection duration;
If the fuel cannot be injected within the preset fuel injection duration, adjusting the crank angle of the initial fuel injection and the current fuel injection duration according to the total fuel injection quantity, the current rail pressure and the preset fuel injection duration, adjusting the injection rate within the preset fuel injection duration when the current fuel injection is performed, and injecting fuel into the combustion chamber according to the adjusted crank angle of the initial fuel injection, the adjusted fuel injection duration and the adjusted injection rate.
As a preferable mode of the engine control method, a crank angle corresponding to when the central oil beam collides with the highest point of the throat of the lower combustion pit is k degrees CA;
the crank angle range corresponding to the preset oil injection duration is (-k+A) ° CA to |k|° CA;
the preset starting oil injection crank angle is (-k+A) CA;
Wherein A is a positive number.
As a preferable scheme of the engine control method, the step of adjusting the crank angle of the initial oil injection and the duration of the current oil injection according to the total oil injection quantity, the current rail pressure and the preset oil injection duration comprises the following steps:
calculating according to the total fuel injection quantity, the current rail pressure and the preset fuel injection duration to obtain the fuel quantity which cannot be injected in the preset fuel injection duration;
Preliminarily determining the crank angle of initial oil injection of the present time by using the fuel quantity which cannot be completely injected;
judging whether the initially determined crank angle of the initial oil injection is earlier than the limit oil injection advance angle corresponding to the explosion pressure limit value;
If the initially determined crank angle of the initial oil injection is earlier than the limit oil injection advance angle corresponding to the explosion pressure limit value, determining the limit oil injection advance angle corresponding to the crank angle=explosion pressure limit value of the initial oil injection, and determining the crank angle range corresponding to the duration of the oil injection as limit oil injection advance angles (CA) to (k) degrees corresponding to the explosion pressure limit value;
If the initially determined crank angle of the current start oil injection is behind the limit oil injection advance angle corresponding to the explosion pressure limit value, determining the crank angle of the current start oil injection as [ I k I+A+B ] CA, and determining the crank angle range corresponding to the duration of the current oil injection as [ I k I+A+B) CA to I k I CA;
wherein B is a positive number.
As a preferable scheme of the engine control method, the specific steps of adjusting the injection rate in the preset injection duration during the current injection include:
and adjusting the injection rate (the maximum injection rate C) in the preset injection duration during the current injection, wherein C is more than or equal to 0.5 and less than or equal to 1.
As a preferable scheme of the engine control method, when the engine runs at high load, whether the crank angle of starting oil injection at the present time is adjusted is determined according to the oil consumption of the engine and the exhaust smoke of the engine;
if the oil injection starting crank angle is not adjusted, oil is injected into the combustion chamber according to the preset oil injection starting crank angle;
and if the initial oil injection crank angle is adjusted, adjusting the initial oil injection crank angle according to the oil consumption of the engine and the exhaust smoke of the engine, and injecting oil into the combustion chamber according to the adjusted initial oil injection crank angle.
As a preferable scheme of the engine control method, the injection rate of each injection in the preset injection duration is adjusted to be less than or equal to (the maximum injection rate of each injection is equal to D) when the engine is operated under high load, wherein D is more than or equal to 0.5 and less than or equal to 1.
The invention has the beneficial effects that:
The invention provides an engine piston, an engine and an engine control method. The second annular bulge is arranged on the side wall of the center boss, h3 is smaller than h2 and h1, and the total fuel injection amount is relatively small when the engine runs under low load, so that for the low load running of the engine, most of fuel injected into the lower combustion pit can not diffuse to the center area of the combustion chamber along the side wall of the center boss, so that the fuel injected into the lower combustion pit can be atomized and diffused and combusted in the lower combustion pit as much as possible, the air utilization rate of air in the lower combustion pit can be effectively improved, the combustion effect of mixed combustion of the fuel and the air in the lower combustion pit can be effectively improved, the heat loss caused by the diffusion of the fuel to the center area of the combustion chamber can be effectively reduced, and the loading capacity of the engine can be improved.
Because the total fuel injection quantity is relatively more during the high-load operation of the engine, the protrusion height of the second annular protrusion has smaller blocking effect on the diffusion of the fuel injected into the lower combustion pit to the central area of the combustion chamber along the side wall of the central boss for the high-load operation of the engine by setting h3< h2< h1, so that the phenomenon of performance deterioration during the high-load operation of the engine can be effectively reduced.
Therefore, the air utilization rate and the combustion effect can be effectively improved when the engine runs at low load, the loading capacity of the engine can be effectively improved, and the phenomenon of deterioration of the engine performance can be effectively reduced when the engine runs at high load. Therefore, the working performance of the engine can be effectively improved.
Drawings
FIG. 1 is a schematic view of a combustion chamber provided in accordance with an embodiment of the present invention;
FIG. 2 is a dimensional view of a combustion chamber provided by an embodiment of the present invention;
FIG. 3 is a fuel distribution diagram of a combustion chamber provided by an embodiment of the present invention;
FIG. 4 is a flowchart I of an engine control method provided by an embodiment of the present invention;
FIG. 5 is a second flowchart of an engine control method provided by an embodiment of the present invention;
FIG. 6 is a flowchart III of an engine control method provided by an embodiment of the present invention;
FIG. 7 is a flow chart diagram fourth of an engine control method provided by an embodiment of the present invention;
FIG. 8 is a graph comparing pressure curves before and after optimizing engine low load operation provided by an embodiment of the present invention;
FIG. 9 is a graph comparing instantaneous heat release rate curves before and after optimization during low load operation of an engine provided by an embodiment of the present invention;
FIG. 10 is a graph of the atomization spread of an optimized front center oil bundle in a lower combustion pocket at 0 CA provided by an embodiment of the present invention;
FIG. 11 is a graph of the atomization spread of an optimized center oil bundle in a lower combustion pocket at 0 CA provided by an embodiment of the present invention;
FIG. 12 is a graph of optimizing combustion in the front lower combustion pocket at 40 CA provided by an embodiment of the present invention;
FIG. 13 is a graph of the combustion effect in an optimized lower back combustion pocket at 40 CA provided by an embodiment of the present invention;
FIG. 14 is a graph comparing pressure curves before and after optimizing an engine high load operation provided by an embodiment of the present invention;
FIG. 15 is a graph comparing instantaneous heat release rate curves before and after optimization during high engine load operation provided by an embodiment of the present invention.
In the figure:
11. a central boss; 12, lower combustion pits, 13, upper combustion pits, 14, second annular protrusions;
2. A combustion chamber.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
In the description of the present invention, unless explicitly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may, for example, be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "right", etc. orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
The invention provides an engine piston, which comprises a piston body, wherein the top of the piston body is provided with a central boss 11 and a first annular bulge, a lower combustion pit 12 is formed between the central boss 11 and the first annular bulge, and an upper combustion pit 13 is formed on the outer periphery side of the first annular bulge on the piston body. The side wall of the central boss 11 is convexly provided with a second annular protrusion 14. The distance between the highest point of the first annular protrusion and the lowest point of the lower combustion pit 12 in the axial direction of the piston body is a first distance h1. The distance between the first contour line and the lowest point of the lower combustion pit 12 in the axial direction of the piston body is a first distance h1, and the first contour line is a connecting contour line far from the lowest point of the lower combustion pit 12 among connecting contour lines of the second annular protrusion 14 and the center boss 11. The spacing between the lobe apex of the second annular lobe 14 and the lowest point of the lower combustion pocket 12 is a second spacing h 2. h2< h1.
The invention also provides an engine, which comprises a cylinder cover, an engine cylinder body and an oil sprayer, wherein a cylinder chamber is formed between the cylinder cover and the engine cylinder body, and the engine also comprises the engine piston. The piston body is arranged in the cylinder chamber in a sliding manner. When the piston body is positioned at the top dead center, a combustion chamber 2 is formed between the cylinder cover and the top of the piston body. The injector is provided in the cylinder head for injecting fuel into the combustion chamber 2. Along the axial direction of the piston body, when the piston body is positioned at the top dead center, the interval between the collision wall point of the central oil beam, which is injected into the collision wall of the lower combustion pit 12, and the lowest point of the lower combustion pit 12 is a third interval h3, wherein h3 is smaller than h2. I.e. h3< h2< h1. It is understood that the sliding direction of the piston body is parallel to the central axis of the piston body.
The second annular bulge 14 is arranged on the side wall of the center boss 11 in a protruding mode, h3 is smaller than h2 is smaller than h1, and the total fuel injection amount is relatively smaller when the engine runs under low load, so that for the low load running of the engine, most of fuel injected into the lower combustion pit 12 can be prevented from diffusing to the center area of the combustion chamber 2 along the side wall of the center boss 11, the fuel injected into the lower combustion pit 12 can be atomized, diffused and combusted in the lower combustion pit 12 as much as possible, the air utilization rate of air in the lower combustion pit 12 can be effectively improved, the combustion effect of mixed combustion of the fuel and the air in the lower combustion pit 12 can be effectively improved, and the heat loss caused by the diffusion of the fuel to the center area of the combustion chamber 2 can be effectively reduced, so that the loading capacity of the engine can be improved when the combustion effect is improved under low load running of the engine, and as can be understood that the exhaust energy of the engine can be synchronously lifted, the rotation speed of the turbine booster can be synchronously lifted, the engine can be synchronously lifted, and the loading capacity of the engine can be further lifted when the engine is in low load running of the engine.
Since the total fuel injection amount is relatively large during the high-load operation of the engine, the protrusion height of the second annular protrusion 14 has a small blocking effect on the diffusion of the fuel injected into the lower combustion pit 12 along the side wall of the central boss 11 to the central area of the combustion chamber 2 during the high-load operation of the engine by setting h3< h2< h1, so that the phenomenon of performance deterioration during the high-load operation of the engine can be effectively reduced.
Therefore, by adopting the engine piston, the air utilization rate and the combustion effect can be effectively improved when the engine runs at low load, the loading capacity of the engine can be effectively improved, and the phenomenon of engine performance deterioration can be effectively reduced when the engine runs at high load. Therefore, the working performance of the engine can be effectively improved.
Specifically, the loading capacity of an engine refers to the output power that the engine can achieve under prescribed conditions. Engine low load operation refers to an engine speed less than a rated speed and/or an engine operating power less than a set operating power split value. The high-load operation of the engine means that the engine speed is equal to the rated speed, and the operating power of the engine is greater than or equal to the set operating power demarcation value. Specifically, with the diesel generator, after the engine speed is increased to the rated speed, the engine speed is constant to the rated speed. The operating power demarcation value is set to be an empirical value obtained by a large number of tests in the earlier stage, or the operating power demarcation value is set to be a power demarcation value. In this embodiment, an exemplary setting sets the operating power split value to 25% of the rated power of the engine.
Preferably, as shown in fig. 2, the distance between the top of the combustion chamber 2 and the lowest point of the lower combustion pocket 12 is the combustion chamber height h in the axial direction of the piston body. h1 = (0.43 to 0.5) h. h3 = (0.7 to 0.8) h1. So set up for the degree of depth of lower burning pit 12 is darker, and makes the piston body be located the top dead center time central oil beam jet into the area that the lower burning pit 12 hits the wall and is located the lower burning pit 12 and is close to the uppermost in lower burning pit 12 to the fuel that makes into in the lower burning pit 12 can be better atomize the diffusion in lower burning pit 12, based on the barrier effect of second annular arch 14, thereby can further promote the effect that the fuel utilized the air in the lower burning pit 12, make the burning heat release in the lower burning pit 12 more concentrated, thereby can further promote the loading ability when engine low load operation.
It is further preferred that the lobe apex of the second annular lobe 14 is located at the same elevation as the most distal end of the lower combustion bowl 12 away from the central axis of the piston body, as shown in fig. 2. Compared to the position where the lobe apex of the second annular lobe 14 is lower than the most distal end of the lower combustion bowl 12 away from the central axis of the piston body, the second annular lobe 14 occupies as little as possible the concentrated area of the combustion heat release of the lower combustion bowl 12, as shown in fig. 3, the shadow in the lower combustion bowl 12 is a substantially concentrated distribution position of the fuel in the lower combustion bowl 12, and secondly, the second annular lobe 14 can be easily processed. In the present embodiment, the cross section of the second annular projection 14 is preferably circular arc-shaped. As an alternative, the lobe apex of the second annular lobe 14 is higher than the furthest end of the lower combustion bowl 12 away from the central axis of the piston body. It will be appreciated that the cross-section of the second annular protrusion 14 is arcuate, but not circular, when the protrusion apex of the second annular protrusion 14 is higher than the furthest end of the lower combustion pocket 12 from the central axis of the piston body.
Wherein, as shown in fig. 2, the diameter of the piston body is defined as D. The diameter of the first contour line is D1, and the first contour line is a connecting contour line of the second annular protrusion 14 and the center boss 11, which is far from the lowest point of the lower combustion pit 12. The diameter of the second contour line is D2, and the second contour line is a connecting contour line near the lowest point of the lower combustion pit 12 among the connecting contour lines of the second annular protrusion 14 and the center boss 11. The corresponding diameter D3 at the furthest end of the lower combustion pocket 12 from the central axis of the piston body, in the radial direction of the piston body. The corresponding diameter D4 at the furthest end of the upper combustion bowl 13 from the central axis of the piston body, in the radial direction of the piston body.
Preferably, as shown in fig. 2, d1= (0.2 to 0.25) D. D2 = (0.3 to 0.35) D. D3 = (0.45 to 0.6) D. By this arrangement, in combination with the first pitch h1 and the third pitch h3, when the engine is operated at a low load, the fuel injected into the lower combustion pit 12 can be atomized and spread and burned in the lower combustion pit 12 as much as possible on the basis that the fuel is prevented from being mostly spread toward the central region of the combustion chamber 2 along the side wall of the central boss 11.
Preferably, as shown in fig. 1-3, the top of the piston body is provided with a recess on the outer peripheral side of the first annular projection, the recess forming an upper combustion recess 13. The distance between the lowest point of the upper combustion pit 13 and the lowest point of the lower combustion pit 12 in the axial direction of the piston body is a fourth distance h4, h4< h1. The angle between the line between the lowest point of the upper combustion recess 13 and the highest point of the first annular projection and the plane perpendicular to the axial direction of the piston body is alpha, 0 deg. < alpha <15 deg.. It will be appreciated that the lowest point of the upper combustion pocket 13 is lower than the highest point of the first annular projection. The arrangement is that the fuel injected into the upper combustion pit 13 flows downwards to the bottom of the upper combustion pit 13 when entering the upper combustion pit 13, so that the fuel injected into the upper combustion pit 13 can be concentrated in the upper combustion pit 13, the spread of the fuel to the peripheral engine cylinder body is reduced, as shown in fig. 3, the shadow in the upper combustion pit 13 is the approximately concentrated distribution position of the fuel in the upper combustion pit 13, so that the fuel injected into the upper combustion pit 13 can be atomized and diffused and combusted in the upper combustion pit 13 as much as possible, the air utilization rate of the fuel for utilizing the air in the upper combustion pit 13 can be effectively improved, the combustion effect of the mixed combustion of the fuel and the air in the upper combustion pit 13 can be effectively improved, the combustion heat release in the upper combustion pit 13 is more concentrated, and the loading capacity of the engine can be further improved.
Specifically, the hatching in the lower combustion pit 12 in fig. 3 is a substantially concentrated distribution position of the fuel in the lower combustion pit 12, and the hatching in the upper combustion pit 13 in fig. 3 is a substantially concentrated distribution position of the fuel in the upper combustion pit 13. As can be seen from fig. 3, by providing the second annular protrusion 14, the fuel injected into the lower combustion pit 12 is substantially concentrated in the shadow region in the lower combustion pit 12 during low load operation of the engine, and the protrusion height of the second annular protrusion 14 has less effect of inhibiting the fuel injected into the lower combustion pit 12 from diffusing toward the central region of the combustion chamber 2 along the side wall of the central boss 11 during high load operation of the engine, and the fuel can diffuse toward the central region of the combustion chamber 2 along the side wall of the central boss 11. By setting h4< h1 and 0 ° < α <15 °, the fuel injected into the upper combustion pit 13 flows downward to the bottom of the upper combustion pit 13 when entering the upper combustion pit 13, so that the fuel injected into the upper combustion pit 13 is substantially concentrated in the shadow region in the upper combustion pit 13.
Preferably, as shown in fig. 2, d4= (0.76-0.83) D. By the arrangement, the diameter D4 corresponding to the most distal end part far away from the central axis of the piston body on the upper combustion pit 13 is larger, and air in a clearance space above the upper combustion pit 13 can be fully utilized when the engine runs under high load, so that the loading capacity of the engine during high load running can be effectively ensured. Wherein the clearance space refers to the clearance space between the cylinder head and above the upper combustion bowl 13.
Specifically, as shown in fig. 2, the interval between the most distal end of the upper combustion pit 13, which is away from the central axis of the piston body, and the lowest point of the lower combustion pit 12 in the axial direction of the piston body is a fifth interval h5, h1< h5< h.
It will be appreciated that, as shown in fig. 2, the injection angle of the central oil beam can be calculated according to the height h of the combustion chamber, the third interval h3, and the diameter D3 corresponding to the point where the central oil beam is injected into the wall of the lower combustion pit 12 when the piston body is located at the top dead center, so as to determine the cone angle range of the injection hole on the injector. Fuel is injected into the combustion chamber 2 from the nozzle holes of the fuel injector. The specific structure of the fuel injector belongs to the prior art, and is not described herein.
The invention also provides an engine control method for the engine.
The engine control method includes:
the preset start oil injection crank angle and the preset oil injection duration are determined in advance according to the crank angle when the central oil beam collides with the highest point of the throat of the lower combustion pit 12.
When the piston body is positioned at the top dead center, the corresponding crank angle is 0 CA when the central oil beam is injected into the wall of the lower combustion pit 12.
The crank angle corresponding to the highest point of the throat of the lower combustion pit 12 at which the central oil gallery hits the wall is k DEG CA. Where k is positive or negative. Specifically, the crank angle k corresponding to the case where the central oil bundle hits the wall at the highest point of the throat of the lower combustion pit 12 before the piston body reaches the top dead center is negative. After the piston body reaches the top dead center, the crank angle k corresponding to the case where the central oil bundle hits the wall at the highest point of the throat of the lower combustion pit 12 is positive. It will be appreciated that the value of k will be different for different engine specifications.
The crank angle range corresponding to the preset oil injection duration is (-k+A) ° CA to |k|CA.
The crank angle for starting oil injection is preset to be (-k+A) CA. Wherein A is a positive number. The term k refers to the absolute value of k. It will be appreciated that fuel injection begins before the piston body reaches top dead center.
And presetting the crank angle of the oil injection at the same time as the angle of the oil injection.
In the present embodiment, an exemplary setting a=7. The fuel does not directly hit the wall during initial injection, and the fuel starts to hit the wall after the crank angle is changed by about 7 CA. In the present embodiment, therefore, the start-injection crank angle= - (|k|+7) ° CA is preset. It will be appreciated that the value of a is different for different engine sizes. The value of A is related to the crank angle through which the fuel is ejected to the fuel impingement wall.
As shown in fig. 4 and 5, the engine control method further includes:
s100, acquiring the total fuel injection quantity and the current rail pressure.
And S200, determining whether the internal combustion oil can be completely injected within the preset injection duration according to the total injection quantity and the current rail pressure.
If the fuel can be injected within the preset injection duration, step S300 is performed.
S300, injecting oil into the combustion chamber 2 according to a preset starting oil injection crank angle and a preset oil injection duration.
It can be understood that the crank angle range corresponding to the preset oil injection duration is set to be (-k+A) CA to |k|CA, the preset oil injection start crank angle is set to be (-k+A) CA, when the piston body is positioned at the top dead center, the wall collision point of the central oil beam injected into the combustion chamber is positioned in the lower combustion pit 12, for the low-load operation of the engine, the oil injection is started in the process of moving the piston body to the top dead center, a small part of injected fuel is injected into the upper combustion pit 13, a large part of injected fuel is injected into the lower combustion pit 12, and the fuel is injected into the lower combustion pit 12 approximately all in the process of moving the piston body from the top dead center downwards, so that the main oil injection quantity is injected into the lower combustion pit 12, and a small part of injected into the upper combustion pit 13, thereby the effect of utilizing the air in the lower combustion pit 12 can be better improved, the combustion in the lower combustion pit 12 is more concentrated, and the load operation capability of the engine can be further improved.
Secondly, as h1= (0.43-0.5) h and h3= (0.7-0.8) h1, the depth of the lower combustion pit 12 is deeper, and the collision wall point of the central oil beam, which is injected into the collision wall of the lower combustion pit 12 when the piston body is positioned at the top dead center, is positioned in the lower combustion pit 12 and is close to the uppermost area in the lower combustion pit 12, for low-load operation of the engine, most of the fuel injected into the lower combustion pit 12 can be better atomized and diffused in the lower combustion pit 12, and the effect of the fuel on utilizing the air in the lower combustion pit 12 can be further improved based on the blocking effect of the second annular protrusion 14, so that the combustion heat release in the lower combustion pit 12 is more concentrated, and the loading capacity of the engine in low-load operation can be further improved.
Secondly, since h4< h1 and 0 ° < α <15 °, for engine low load operation, the fuel injected into the upper combustion pit 13 flows down to the bottom of the upper combustion pit 13 when entering into the upper combustion pit 13, so that the fuel injected into the upper combustion pit 13 can be concentrated into the upper combustion pit 13, and spread of the fuel to the peripheral engine cylinder is reduced, thereby improving the effect of the fuel on utilizing air in the upper combustion pit 13, and the heat release of combustion in the upper combustion pit 13 is more concentrated, thereby further improving the loading capability of the engine in low load operation.
If the fuel cannot be injected within the preset injection duration, step S400 is performed.
S400, adjusting the crank angle of the initial oil injection and the duration of the current oil injection according to the total oil injection quantity, the current rail pressure and the preset duration of the oil injection, adjusting the injection rate of the current oil injection within the preset duration of the oil injection, and injecting oil into the combustion chamber 2 according to the adjusted crank angle of the initial oil injection, the adjusted duration of the oil injection and the adjusted injection rate.
Specifically, as shown in fig. 4 and 5, the specific steps of adjusting the crank angle of the initial injection and the duration of the current injection according to the total injection quantity, the current rail pressure and the preset injection duration include:
And S410, calculating to obtain the fuel quantity which cannot be completely sprayed in the preset fuel injection duration according to the total fuel quantity, the current rail pressure and the preset fuel injection duration.
Specifically, the amount of fuel that can be injected within the preset fuel injection duration is calculated based on the current rail pressure and the preset fuel injection duration. And then calculating the difference between the total fuel injection quantity and the fuel quantity which can be injected within the preset fuel injection duration, namely the fuel quantity which can not be injected within the preset fuel injection duration. The specific calculation method for calculating the fuel quantity capable of being injected in the preset fuel injection duration according to the current rail pressure and the preset fuel injection duration belongs to the prior art, and therefore will not be described herein.
S420, preliminarily determining the crank angle of initial oil injection of the current time= - (|k|+A+B) ° CA according to the fuel quantity which cannot be completely injected.
Specifically, the value of B is checked from the first table according to the amount of fuel that cannot be completely injected. The first table is formed by fuel quantity which can not be sprayed and the value of B. The first table is an empirical table obtained from a number of previous trials. B is a positive number.
S430, judging whether the initially determined crank angle of the initial oil injection is earlier than the limit oil injection advance angle corresponding to the explosion pressure limit value. The limit oil injection advance angle corresponding to the explosion pressure limit value is an empirical value obtained by a large number of tests in the earlier stage. Under different loads, the limit oil injection advance angles corresponding to the explosion pressure limit value of the engine are different. The detonation pressure limiting value refers to a maximum detonation pressure value corresponding to the structural strength of the engine.
If the initially determined crank angle of the current start injection is earlier than the limit injection advance angle corresponding to the explosion pressure limit, step S440 is performed.
S440, determining a limit oil injection advance angle corresponding to the oil injection crank angle=explosion pressure limit value at the beginning time, and determining a crank angle range corresponding to the oil injection duration at the beginning time as limit oil injection advance angles |k||CA corresponding to the explosion pressure limit value.
If the initially determined crank angle for the start of injection is after the limit injection advance angle corresponding to the explosion pressure limit value, step S450 is executed.
S450, determining the crank angle of the current start oil injection= - (|k|+A+B) ° CA, and determining the crank angle range corresponding to the duration of the current oil injection as- (|k|+A+B) ° CA to |k|CA.
The specific steps of adjusting the injection rate in the preset injection duration during the current injection include:
and (3) adjusting the injection rate in the preset injection duration during the current injection to be more than or equal to (the maximum injection rate during the current injection is equal to C). Wherein, C is more than or equal to 0.5 and less than or equal to 1.
It can be understood that by adjusting the timing of starting the injection before and adjusting the injection rate in the preset injection duration to be larger during the current injection, the total injection amount can be injected as completely as possible during the current injection duration, and the fuel injected into the combustion chamber 2 can be further injected into the lower combustion pit 12 approximately uniformly, so that the combustion in the lower combustion pit 12 is more concentrated, and the loading capability of the engine can be further improved during the low-load operation of the engine.
In this embodiment, an exemplary setting is to adjust the injection rate in the preset injection duration during the current injection=the maximum injection rate during the current injection 0.5.
The single oil injection process of the oil injector comprises the steps that when the oil injector starts oil injection, the oil injection rate gradually increases from zero to the maximum oil injection rate and stabilizes to the maximum oil injection rate, and when the oil injector finishes oil injection, the oil injection rate gradually decreases from the maximum oil injection rate to zero.
As shown in fig. 6 and 7, the engine control method further includes:
s500, acquiring the oil consumption of the engine and the tail exhaust smoke degree of the engine.
Specifically, engine fuel consumption refers to the average of the total fuel consumed during engine operation.
Specifically, the exhaust smoke level of the engine is monitored by a smoke level sensor.
S600, determining whether to adjust the crank angle of the start oil injection at this time according to the oil consumption of the engine and the exhaust smoke of the tail gas of the engine.
Specifically, step S600 includes:
Judging whether the oil consumption of the engine is greater than or equal to the set oil consumption, and judging whether the exhaust smoke of the engine is greater than or equal to the set smoke value. The fuel consumption is set to be an empirical value obtained by a large number of tests in the early stage, and the smoke intensity is set to be an empirical value obtained by a large number of tests in the early stage.
If the engine oil consumption is smaller than the set oil consumption and the exhaust smoke level of the engine is smaller than the set smoke level value, the crank angle of the start of oil injection is not adjusted, and step S700 is executed.
S700, injecting fuel into the combustion chamber 2 according to the preset starting fuel injection crank angle.
If the fuel consumption of the engine is greater than or equal to the set fuel consumption and/or the exhaust smoke of the engine is greater than or equal to the set smoke value, the crank angle of the fuel injection started at this time is adjusted, and step S800 is executed.
S800, adjusting the crank angle of the initial oil injection according to the oil consumption of the engine and the exhaust smoke of the engine, and injecting oil into the combustion chamber 2 according to the adjusted crank angle of the initial oil injection.
Specifically, as shown in fig. 6 and 7, the specific steps of adjusting the crank angle of the initial fuel injection according to the fuel consumption of the engine and the exhaust smoke of the engine include:
And S810, preliminarily determining the crank angle of initial oil injection of the present time= - (|k|+A+E) ° CA according to the oil consumption of the engine and the exhaust smoke of the engine. The fuel injection time is adjusted before the fuel injection, so that the mixing effect of fuel and air is improved, the fuel consumption of the engine is reduced, and the tail exhaust smoke level of the engine is reduced.
Specifically, the value of E is checked from the second table according to the fuel consumption of the engine and the exhaust smoke level of the tail gas of the engine. The second table is formed by the engine fuel consumption, the exhaust smoke of the engine and the value of E. The second table is an empirical table obtained from a number of previous trials. E is a positive number.
S820, judging whether the initially determined crank angle of the initial oil injection is earlier than the limit oil injection advance angle corresponding to the explosion pressure limit value. The limit oil injection advance angle corresponding to the explosion pressure limit value is an empirical value obtained by a large number of tests in the earlier stage. Under different loads, the limit oil injection advance angles corresponding to the explosion pressure limit value of the engine are different. The detonation pressure limiting value refers to a maximum detonation pressure value corresponding to the structural strength of the engine.
If the initially determined crank angle of the current start fuel injection is earlier than the limit fuel injection advance angle corresponding to the explosion pressure limit, step S830 is executed.
And S830, determining a limit oil injection advance angle corresponding to the current start oil injection crank angle=explosion pressure limit value.
If the initially determined crank angle for the initial injection is after the limit injection advance angle corresponding to the explosion pressure limit, step S840 is performed.
And S840, determining the crank angle of the current start oil injection= - (|k|+A+E) ° CA.
Preferably, the injection rate at each injection is adjusted to less than or equal to the predetermined injection duration (maximum injection rate at each injection D) at high engine load operation. Wherein D is more than or equal to 0.5 and less than or equal to 1. That is, in the process of executing steps S700 and S800, the injection rate at each injection is adjusted to be less than or equal to the injection rate at the preset injection duration (the injection rate at each injection is equal to D).
By the arrangement, when the engine runs under high load, the quantity of fuel injected into the lower combustion pit 12 in the preset fuel injection duration can be effectively reduced, the second annular protrusion 14 is arranged in combination with the lower combustion pit 12, the height of the second annular protrusion 14 has a small blocking effect on the diffusion of the fuel injected into the lower combustion pit 12 to the central area of the combustion chamber 2 along the side wall of the central boss 11, and the phenomena of overhigh fuel concentration in the lower combustion pit 12 and large tail exhaust smoke of the engine caused by excessive fuel injected into the lower combustion pit 12 in the preset fuel injection duration can be further avoided, so that the phenomenon of performance deterioration during the high load running of the engine can be further reduced.
Secondly, when the engine runs under high load, h4 is less than h1 and 0 degrees is less than alpha is less than 15 degrees by combining the structural characteristics of the upper combustion pit 13, so that the fuel injected into the upper combustion pit 13 before and after the preset fuel injection duration can fully utilize the air in the upper combustion pit 13, and the loading capacity of the engine during high load running can be further ensured.
Secondly, for high-load operation of the engine, as d4= (0.76-0.83) D, the diameter D4 corresponding to the most distal end of the upper combustion pit 13 far away from the central axis of the piston body is larger, so that the fuel oil can fully utilize the air in the clearance space above the upper combustion pit 13, and the loading capability of the engine during high-load operation can be further ensured.
In this embodiment, an exemplary setting is to adjust the injection rate for a preset injection duration for each injection at high engine load operation=the maximum injection rate for each injection 0.5.
Therefore, by adopting the engine control method, the air utilization rate and the combustion effect can be further improved when the engine runs at low load, the loading capacity of the engine can be further improved, the phenomenon of deterioration of the engine performance can be further reduced when the engine runs at high load, and the loading capacity of the engine is ensured when the engine runs at high load. Thereby further improving the working performance of the engine.
The method comprises the steps of judging whether the rotating speed of the engine is smaller than the set rotating speed in real time in the running process of the engine, and judging whether the power of the engine is larger than or equal to the set running power demarcation value in real time. And if the engine speed is equal to the set speed and the engine power is greater than or equal to the set running power demarcation value, determining that the engine runs under high load. And if the engine speed is smaller than the set speed and/or the engine power is smaller than the set running power demarcation value, determining that the engine runs under low load. Wherein the set rotational speed is a rated rotational speed of the engine.
Specifically, in the present embodiment, |k|=7 is exemplified as an example. The crank angle range corresponding to the preset oil injection duration is-14 degrees CA-7 degrees CA, and the crank angle for starting oil injection is-14 degrees CA.
As is evident from fig. 8, at low engine load operation, the in-cylinder pressure of the engine increases significantly after optimization after the crank angle is-6 ° CA. As is evident from fig. 9, at low engine load operation, the instantaneous heat release rate of fuel combustion increases significantly after optimization after a crank angle of-8 CA. Thereby effectively improving the loading capacity of the engine in low-load operation. The in-cylinder pressure of the engine refers to the cylinder pressure in a portion of the cylinder chamber of the engine that communicates with the combustion chamber 2.
As is evident from a comparison of fig. 10 and 11, at 0 ° CA, the atomization and diffusion effect of the optimized central bundle of oil in the lower combustion pocket 12 is significantly improved.
As is apparent from comparing fig. 12 and 13, at 40 ° CA, the combustion area in the lower combustion pit 12 is greatly expanded, so that the air utilization rate is effectively improved, and for low-load operation of the engine, the second annular protrusion 14 can effectively block the combustion area in the lower combustion pit 12 from further diffusing toward the central area of the combustion chamber 2.
Specifically, in the embodiment, when the engine runs under low load, the air utilization rate is improved by 14%, the loading capacity of the engine is enhanced by 9%, and the exhaust temperature of the engine is improved by 20-30 ℃.
As is apparent from fig. 14, at the time of high load operation of the engine, the in-cylinder pressure of the engine is kept substantially uniform before and after the optimization. As is apparent from fig. 15, the instantaneous heat release rate of the fuel combustion is kept substantially uniform before and after the optimization at the time of the high load operation of the engine. Thereby effectively reducing the performance deterioration phenomenon of the engine during high-load operation.
It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Various obvious changes, rearrangements and substitutions can be made by those skilled in the art without departing from the scope of the invention. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (14)
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