A four-valve double-channel structure diesel engine for improving combustion efficiency

Abstract

This invention discloses a four-valve dual-channel diesel engine with improved combustion efficiency, comprising an engine block, a crankcase mounted on the engine block, a cylinder head that mates with the crankcase, a flywheel fixedly connected to the crankshaft in the crankcase, and a cooling fan mounted on one side of the engine block. The cylinder head has intake and exhaust channels, which are connected to the valves. The cylinder head has a four-valve dual-channel structure, with two intake and two exhaust channels. The valves include intake valves and exhaust valves. This invention increases the total intake valve area by 30-40%, reducing pumping losses, especially at low speeds such as 1500 rpm, resulting in an 8-12% increase in torque. The air-fuel mixture quality is improved: high-pressure common rail injectors (e.g., 2500 bar) combined with dual-channel airflow reduce the average fuel soter diameter to below 10 μm. Thermodynamics is optimized: the differentiated airflow of the dual channels delays local knocking, allowing for higher compression ratios up to 20:1, and indicating a thermal efficiency exceeding 48%.

Description

Technical Field

[0001] This invention relates to the separate delivery of air and fuel to the cylinder, and more specifically to a four-valve dual-channel diesel engine with improved combustion efficiency. Background Technology

[0002] Diesel engines rely on high compression ratios to ignite diesel fuel, thus requiring extremely high airflow efficiency and air-fuel mixture quality. Four-valve dual-channel designs are common in mid-to-high-end diesel engines (such as commercial vehicles and construction machinery) to meet the demands for high power and low emissions. As the name suggests, the number of valves in an engine refers to the sum of the intake and exhaust valves in each cylinder. A four-valve design has two intake valves and two exhaust valves. With two intake valves and two exhaust valves, a single-cylinder four-valve engine has a larger intake and exhaust flow area, reducing flow resistance losses. The vertically positioned injector also results in higher intake efficiency, more complete combustion, and faster combustion speed, leading to lower fuel consumption. Simultaneously, the two intake valves facilitate airflow, reducing CO and HC emissions. The shorter combustion duration reduces the formation of nitrogen oxides in the exhaust, lowering aftertreatment system pressure and reducing the risk of aftertreatment malfunctions. Furthermore, reducing the mass of a single valve increases engine speed, resulting in at least a 10% increase in power and torque per unit volume compared to a single-cylinder two-valve engine. The four-valve structure has a higher charging coefficient, allowing for a reduction in exhaust valve diameter, thereby lowering operating temperature and improving reliability. However, combustion efficiency still needs improvement. Patent CN100501137C discloses a vertical single-cylinder diesel engine, comprising a crankcase with a bottom for holding lubricating oil, a cylinder head assembly that matches the crankcase, a cylinder assembly, a fuel system and a valve train that match the cylinder assembly. The crankcase contains a transmission mechanism and an external cooling device. The valve train has a valve cam assembly and a rocker arm assembly. The valve cam assembly is fixed in the gear chamber of the crankcase. The rocker arm assembly is supported on a rocker arm seat and fixed to the cylinder head assembly. The transmission mechanism includes a starter motor, a flywheel gear, and a crankshaft located in the crankcase, connected in sequence. The crankshaft has a transmission arm that connects to the piston in the cylinder assembly. One end of the crankshaft has a timing gear. The rocker arm shaft of the valve train has an oil inlet and an oil outlet that communicate with the inner cavity of the rocker arm shaft. The crankcase has a lubricating oil supply mechanism that matches the oil inlet. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects in the prior art and provide a four-valve dual-channel diesel engine with improved combustion efficiency. By adopting a four-valve dual-channel structure, the charging efficiency is optimized and the combustion efficiency is improved.

[0004] To achieve the above objectives, the technical solution of this invention is to design a four-valve dual-channel diesel engine with improved combustion efficiency, comprising an engine block, a crankcase mounted on the engine block, a cylinder head that mates with the crankcase, a flywheel fixedly connected to the crankshaft of the crankcase, and a cooling fan mounted on one side of the engine block; the cylinder head is provided with an intake channel and an exhaust channel, which are connected to valves, and the cylinder head has a four-valve dual-channel structure, with two intake channels and two exhaust channels; the valves include an intake valve and an exhaust valve; the exhaust channels are a short exhaust channel and a long exhaust channel; there are two intake valves and two exhaust valves, wherein the two independent intake channels are connected to the intake manifold, and the ends of the two independent intake channels are respectively connected to the two intake valves via branch pipes; the two exhaust valves are respectively connected to a short exhaust channel and a long exhaust channel; both the long exhaust channel and the short exhaust channel are connected to the exhaust manifold, and the exhaust manifold is connected to the turbine; a fuel injector is installed on the top of the cylinder head.

[0005] A further technical solution is that one of the two intake channels is a spiral channel with an involute spiral shape along the axis of the intake channel, and the other is a tangential straight channel with a tangential direction relative to the cylinder centerline.

[0006] Design purpose: Channel A (spiral channel): generates strong vortices. Channel B (Tangential Channel): Ensures high flow rate The four-valve, dual-channel structure optimizes inflation efficiency. Dual-channel air intake: Two independent intake ducts (usually designed as helical + tangential) generate strong swirl and tumble in the intake, improving air utilization by 15-25%. At 2000 rpm, the volumetric efficiency can reach 98% (approximately 85% for two-valve models).

[0007] Four-valve layout: The total intake valve area is increased by 30-40%, reducing pumping losses, and especially increasing torque by 8-12% at low speeds (such as 1500 rpm).

[0008] Improved air-fuel mixture quality: Enhanced fuel atomization: High-pressure common rail injectors (e.g., 2500 bar) combined with dual-channel airflow can reduce fuel SMD to below 10 μm (compared to approximately 15 μm in conventional designs).

[0009] Thermodynamics is optimized: dual-channel differential airflow delays local knocking, allowing for higher compression ratios (18:1 to 20:1 for diesel engines), and indicating thermal efficiency (ITE) exceeding 48%.

[0010] Another technical solution is that the part of the cylinder head located between the intake valve and the exhaust valve is composed of several connecting strips, which are made of modified aluminum-silicon alloy containing cerium or scandium.

[0011] Under thermal shock, cylinder heads are prone to cracking between valves. Current technology generally employs appropriately increasing the valve spacing to improve the reliability of the cylinder head during low-cycle fatigue. Based on existing experience, the reliability of the cylinder head during low-cycle fatigue can be assessed by the ratio of the valve seat diameter to the valve spacing; the smaller the value, the better the reliability (see Li Qiang's paper "Design of a Four-Valve Cylinder Head for a Low-Fuel-Consumption Light-Duty Diesel Engine" published in the April 2019 issue of *Internal Combustion Engine*). The narrow "nose area" between the valve seats compresses against each other during thermal expansion and contracts under restricted conditions during cooling, generating lateral tensile stress (parallel to the cylinder head surface). This alternating stress is a major cause of fatigue cracking.

[0012] The existing smaller valve spacing is still used (which reduces the overall size of the diesel engine and meets the requirements of lightweight design), but the clearance is designed in advance so that there is a discontinuous space between the valve seats. In this way, the narrow "nose area" between the valve seats will squeeze each other when thermally expanded and have space to contract when cooled. The contraction is no longer restricted. Only the cylinder head part between the valve seats inside and outside the space uses high-cost modified aluminum-silicon alloys containing cerium (Ce) or scandium (Sc), and the cost increase is small.

[0013] Another technical solution is that the valve seats of the intake and exhaust valves on the cylinder head are made of modified aluminum-silicon alloy containing cerium or scandium; the part of the cylinder head located between the intake or exhaust valves consists of several spaced filling parts made of aluminum-silicon alloy and inflatable metal airbags between the filling parts.

[0014] By adopting a reverse approach, the tendency of small valve spacing to crack is utilized, and the cracked part is used as the expansion space of the inflatable metal airbag. The part of the cylinder head located between the intake or exhaust valves still uses the most commonly used aluminum-silicon alloys such as A319 and A356. On the one hand, this reduces costs, and on the other hand, it continues to take advantage of the problem of small valve spacing being prone to cracking. Instead, after cracking, the expansion of the inflatable metal airbag inhibits the shrinkage of the aluminum-silicon alloy filling part.

[0015] A further technical solution is that the inflatable metal airbag is spherical with a wall thickness of 0.3–1.0 mm. A helical spring is fixedly installed inside the spherical shell, and the spherical shell is filled with argon gas. The inflatable metal airbag is made of titanium alloy, and the inner wall of the spherical shell is plated with a pure nickel transition layer with a thickness of 50 μm.

[0016] The metal spherical / ellipsoidal shell has a wall thickness of 0.3–1.0 mm (laser-welded); it has an internal helical spring for auxiliary rebound (such as an Inconel 718 spring), and the spherical shell is filled with argon gas. Titanium alloy (such as TC4 / Ti-6Al-4V) is used as the shell material for the metal inflatable airbag, and the inner wall is plated with a pure nickel transition layer (50 μm thick) to block diffusion.

[0017] The advantages and beneficial effects of this invention are: the total area of ​​the intake valve is increased by 30-40%, pumping loss is reduced, and torque is increased by 8-12% especially in low-speed conditions (such as 1500 rpm).

[0018] Improved air-fuel mixture quality: Enhanced fuel atomization: High-pressure common rail injectors (e.g., 2500 bar) combined with dual-channel airflow can reduce fuel SMD to below 10 μm (compared to approximately 15 μm in conventional designs).

[0019] Thermodynamics is optimized: dual-channel differential airflow delays local knocking, allowing for higher compression ratios (18:1 to 20:1 for diesel engines), and indicating thermal efficiency (ITE) exceeding 48%.

[0020] The existing smaller valve spacing is still used (which reduces the overall size of the diesel engine and meets the requirements of lightweight design), but the clearance is designed in advance so that there is a discontinuous space between the valve seats. In this way, the narrow "nose area" between the valve seats will squeeze each other when thermally expanded and have space to contract when cooled. The contraction is no longer restricted. Only the cylinder head part between the valve seats inside and outside the space uses high-cost modified aluminum-silicon alloys containing cerium (Ce) or scandium (Sc), and the cost increase is small.

[0021] By adopting a reverse approach, the tendency of small valve spacing to crack is utilized, and the cracked part is used as the expansion space of the inflatable metal airbag. The part of the cylinder head located between the intake or exhaust valves still uses the most commonly used aluminum-silicon alloys such as A319 and A356. On the one hand, this reduces costs, and on the other hand, it continues to take advantage of the problem of small valve spacing being prone to cracking. Instead, after cracking, the expansion of the inflatable metal airbag inhibits the shrinkage of the aluminum-silicon alloy filling part. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a first embodiment of a four-valve dual-channel diesel engine with improved combustion efficiency according to the present invention; Figure 2 yes Figure 1 Top view; Figure 3 yes Figure 2 BB-direction sectional view; Figure 4 yes Figure 3 A partially enlarged schematic diagram of the markings on the cylinder head and its surrounding components; Figure 5 yes Figure 1 A magnified view of the upper right corner; Figure 6 This is a schematic diagram of the cylinder head in Embodiment 2 of the present invention; Figure 7 yes Figure 6 Top view; Figure 8 This is a schematic diagram of the cylinder head in Embodiment 3 of the present invention.

[0023] In the diagram: 1. Engine block; 2. Crankcase; 3. Cylinder head; 4. Crankshaft; 5. Flywheel; 6. Cooling fan; 7. Intake passage; 8. Exhaust passage; 9. Intake valve; 10. Exhaust valve; 11. Exhaust manifold; 12. Turbine; 13. Injector; 14. Connecting strip; 15. Valve seat; 16. Filler section; 17. Inflatable metal airbag. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0025] Example 1: As Figures 1 to 5 As shown, this invention is a four-valve dual-channel diesel engine with improved combustion efficiency, comprising an engine block 1, a crankcase 2 mounted on the engine block, a cylinder head 3 that mates with the crankcase, a flywheel 5 fixedly connected to the crankshaft 4 in the crankcase, and a cooling fan 6 mounted on one side of the engine block; the cylinder head is provided with an intake passage 7 and an exhaust passage 8, which are connected to valves, and the cylinder head has a four-valve dual-channel structure, with two intake passages and two exhaust passages each; the valves include an intake valve 9 and an exhaust valve 10; the exhaust passage consists of a short exhaust passage and a long exhaust passage; there are two intake valves and two exhaust valves, where the two independent intake passages are connected to the intake manifold, and the ends of the two independent intake passages are respectively connected to the two intake valves via branch pipes, and the two exhaust valves are respectively connected to a short exhaust passage and a long exhaust passage; the long exhaust passage and the short exhaust passage are both connected to an exhaust manifold 11, and the exhaust manifold is connected to a turbine 12; an injector 13 is provided on the top of the cylinder head.

[0026] The two intake channels are a spiral channel with an involute spiral shape along the axis of the intake channel, and a tangential straight channel with a tangential direction relative to the cylinder centerline.

[0027] The turbine is fixedly connected to the engine block via a bracket; it features a four-valve, dual-channel structure, with two independent intake channels supplying two sets of intake valves via branch pipes, and two exhaust channels collecting exhaust output in pulse-group configurations. The intake channels consist of one spiral channel (strong vortex) and one tangential channel (high flow rate); the exhaust channels feature a design with varying lengths of branches. Two independent main intake channels (channels A / B) branch from the main intake manifold, but their ends branch to supply the intake valves on the same side.

[0028] Design purpose: Channel A (spiral channel): generates strong vortices. Channel B (Tangential Channel): Ensures high flow rate The four-valve, dual-channel structure optimizes inflation efficiency. Dual-channel air intake: Two independent intake ducts (usually designed as helical + tangential) generate strong swirl and tumble in the intake, improving air utilization by 15-25%. At 2000 rpm, the volumetric efficiency can reach 98% (approximately 85% for two-valve models).

[0029] Four-valve layout: The total intake valve area is increased by 30-40%, reducing pumping losses, and especially increasing torque by 8-12% at low speeds (such as 1500 rpm).

[0030] Improved air-fuel mixture quality: Enhanced fuel atomization: High-pressure common rail injectors (e.g., 2500 bar) combined with dual-channel airflow can reduce fuel SMD to below 10 μm (compared to approximately 15 μm in conventional designs).

[0031] Thermodynamics is optimized: dual-channel differential airflow delays local knocking, allowing for higher compression ratios (18:1 to 20:1 for diesel engines), and indicating thermal efficiency (ITE) exceeding 48%.

[0032] Example 2: The difference from Example 1 is that, as shown in Example 2... Figure 6 , Figure 7 As shown (for ease of illustration), Figure 7 (Only some connecting strips are shown). The portion of the cylinder head 3 located between the intake valve 9 or the exhaust valve 10 is composed of several connecting strips 14, which are made of a modified aluminum-silicon alloy containing cerium or scandium.

[0033] Under thermal shock, the cylinder head is prone to cracking between valves. Current technology generally adopts the method of appropriately increasing the valve spacing to improve the reliability of the cylinder head in low-cycle fatigue. According to existing experience, the reliability of the cylinder head in low-cycle fatigue can be examined by the ratio of the seat diameter to the valve spacing. The smaller the value, the better the reliability (see Li Qiang's paper "Design of Four-Valve Cylinder Head for Low Fuel Consumption Light-Duty Diesel Engine" published in the April 2019 issue of "Internal Combustion Engine").

[0034] The narrow "bridge area" between the valve seats compresses against each other during thermal expansion and contracts under limited pressure during cooling, generating lateral tensile stress (parallel to the cylinder head surface). This alternating stress is a major cause of fatigue cracking.

[0035] The existing smaller valve spacing is still used (which reduces the overall size of the diesel engine and meets the requirements of lightweight design), but the clearance is designed in advance so that there is a discontinuous space between the valve seats. In this way, the narrow "nose area" between the valve seats will squeeze each other when thermally expanded and have space to contract when cooled. The contraction is no longer restricted. Only the cylinder head part between the valve seats inside and outside the space uses high-cost modified aluminum-silicon alloys containing cerium (Ce) or scandium (Sc), and the cost increase is small.

[0036] Example 3: The difference from Example 2 is that, as shown in Example 3... Figure 8 As shown, the valve seats 15 of the intake valve 9 and exhaust valve 10 on the cylinder head are both made of modified aluminum-silicon alloy containing cerium or scandium; the part of the cylinder head located between the intake valve or the exhaust valve consists of several spaced filling parts 16 made of aluminum-silicon alloy and inflatable metal airbags 17 between the filling parts.

[0037] By adopting a reverse approach, the tendency of small valve spacing to crack is utilized, and the cracked part is used as the expansion space of the inflatable metal airbag. The part of the cylinder head located between the intake or exhaust valves still uses the most commonly used aluminum-silicon alloys such as A319 and A356. On the one hand, this reduces costs, and on the other hand, it continues to take advantage of the problem of small valve spacing being prone to cracking. Instead, after cracking, the expansion of the inflatable metal airbag inhibits the shrinkage of the aluminum-silicon alloy filling part.

[0038] After the cylinder head is cast and T6 / T7 heat treatment is completed, the surface of the areas to be strengthened is cleaned. Then, nickel-based alloy powder is melted by a laser beam (power 1–3 kW) and deposited layer by layer in the target areas such as valve seats (thickness typically 0.5–2 mm).

[0039] The inflatable metal airbag is spherical with a wall thickness of 0.3–1.0 mm. A helical spring is fixed inside the spherical shell, which is filled with argon gas. The inflatable metal airbag is made of titanium alloy, and the inner wall of the spherical shell is plated with a pure nickel transition layer with a thickness of 50 μm.

[0040] The metal spherical / ellipsoidal shell has a wall thickness of 0.3–1.0 mm (laser-welded); it has an internal helical spring for auxiliary rebound (such as an Inconel 718 spring), and the spherical shell is filled with argon gas. Titanium alloy (such as TC4 / Ti-6Al-4V) is used as the shell material for the metal inflatable airbag, and the inner wall is plated with a pure nickel transition layer (50 μm thick) to block diffusion.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A four-valve dual passage structure diesel engine for improving combustion efficiency, characterized in that, The engine comprises a body, a crankcase installed on the body, a cylinder head matched with the crankcase, a flywheel fixedly connected to a crankshaft of the crankcase, and a cooling fan installed on one side of the body; the cylinder head is provided with an air inlet passage and an air outlet passage, the air inlet passage and the air outlet passage are communicated with valves, the cylinder head is a four-valve double passage structure, the air inlet passage and the air outlet passage are each provided with two passages; the valves include air inlet valves and air outlet valves; the air outlet passage is a short air outlet passage and a long air outlet passage; the air inlet valves and the air outlet valves are each provided with two valves, two independent air inlet passages are communicated with an air inlet manifold, and the two independent air inlet passages are respectively communicated with two air inlet valves through branch pipes; two air outlet valves are respectively communicated with a short air outlet passage and a long air outlet passage; the long air outlet passage and the short air outlet passage are communicated with an air outlet manifold, the air outlet manifold is communicated with a turbine; an oil injector is arranged on the top of the cylinder head; one of the two air inlet passages is a spiral passage with an involute spiral axis, and the other is a tangential straight passage with a tangential direction relative to the center line of the cylinder; the part of the cylinder head between the air inlet valves and between the air inlet valves and the air outlet valves is composed of a plurality of connecting strips, and the connecting strips are made of a modified aluminum-silicon alloy containing cerium or containing scandium.

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