Combustion chamber with continuously adjustable compression ratio and adjusting method

Abstract

The invention discloses a combustion chamber with a continuously adjustable compression ratio, which comprises a cylinder body, a piston, a piston rod and a piston rod, the piston is arranged in the cavity and can move along the cavity, and the outer edge, perpendicular to the moving direction, of the piston is sealed with the inner wall of the cavity; the first end of the piston rod is connected with the piston, and the second end of the piston rod extends out of the cavity; the first end of the adjusting rod is detachably connected with the second end of the piston rod; the first end of the driving rod is connected with the second end of the adjusting rod, and the connecting length of the driving rod and the adjusting rod is adjustable; and the end part, far away from the piston rod, of the cylinder body is sealed. The invention further discloses an adjusting method of the compression ratio. According to the invention, continuous adjustment of any compression ratio in a wide range is realized.

Description

Technical Field

[0001] This invention relates to the field of combustion power device technology, and in particular to a combustion chamber with continuously adjustable compression ratio and an adjustment method thereof. Background Technology

[0002] Fuel combustion is the primary mode of energy conversion in land, sea, air, and space propulsion systems. Various propulsion systems release the chemical energy of fuel and convert it into mechanical energy output through the combustion process, providing driving force for the engine. For land and sea equipment, reciprocating piston engines, or internal combustion engines, are the main power units for various vehicles and ships. Since its inception, the core of all theoretical and technological advancements in internal combustion engines has revolved around improving thermal efficiency, i.e., the chemical energy conversion rate. Whether it's a compression-ignition or spark-ignition engine, the compression ratio is the most important parameter determining thermal efficiency. The higher the compression ratio, the higher the thermal efficiency. However, increasing the compression ratio brings a series of problems to internal combustion engines. For spark-ignition internal combustion engines, a high compression ratio easily induces in-cylinder knock, causing structural damage. Knock is generally considered an abnormal combustion phenomenon caused by the spontaneous combustion of the end mixture, and it is extremely destructive. Therefore, the compression ratio of spark-ignition internal combustion engines cannot be designed to be very high due to the limitation of knock. For compression-ignition engines, although they are less affected by knock, the limited compression stroke, necessary combustion chamber space, and mechanical strength restrict further increases in the compression ratio. Therefore, it can be seen that the compression ratio is the key factor affecting the performance improvement of internal combustion engines. Studying the impact of compression ratio on the performance of internal combustion engines and finding the optimal compression ratio are the top priorities in the development of internal combustion engines today.

[0003] Compression ratio is defined as the ratio of the cylinder volume before compression to the combustion chamber volume after compression. An internal combustion engine typically corresponds to only one compression ratio. Therefore, testing compression ratio adjustment in a real internal combustion engine is extremely complex, requiring significant manpower, resources, and time. To address this issue, using a rapid compressor to study the impact of compression ratio on combustion is a widely accepted alternative. A rapid compressor is a test device that replicates the compression stroke of an internal combustion engine independently. Its principle is to create an ideal high-temperature, high-pressure environment for fuel combustion performance testing through adiabatic compression of the piston. Because a rapid compressor focuses only on a single compression process, its structural complexity is far lower than that of an internal combustion engine, and the compression ratio can be changed relatively easily, making it an excellent test platform for studying compression ratio. However, while the adjustment methods of rapid compressors at home and abroad differ, they share a common problem: they can only perform quantitative adjustments, i.e., discrete adjustments at a finite number of numerical points, and cannot perform large-scale continuous adjustments. Existing compression ratio adjustment methods mainly rely on changing the cylinder geometry, requiring frequent cylinder disassembly, which is inefficient. Furthermore, current technology calculates the compression ratio by measuring the combustion chamber length before and after compression, which is very inconvenient.

[0004] Therefore, those skilled in the art are dedicated to providing a combustion chamber with continuously adjustable compression ratio and an adjustment method, which enables continuous adjustment of any compression ratio over a wide range and improves the measurement efficiency of compression ratio. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is how to provide a combustion chamber and adjustment method that can achieve continuous adjustment of any compression ratio over a wide range.

[0006] To achieve the above objectives, the present invention provides a combustion chamber with continuously adjustable compression ratio, comprising: The cylinder block has an internal cavity; A piston is disposed within the cavity and is capable of moving along the cavity. The outer edge of the piston, perpendicular to the direction of movement, is sealed to the inner wall of the cavity. A piston rod, the first end of which is connected to the piston, and the second end of which extends out of the cavity; An adjusting rod, the first end of which is detachably connected to the second end of the piston rod; A drive rod, the first end of which is connected to the second end of the adjusting rod, wherein the connection length between the drive rod and the adjusting rod is adjustable; The end of the cylinder block away from the piston rod is sealed.

[0007] Furthermore, the outer edge of the piston is provided with a sealing groove, a guide groove, and a clearance groove.

[0008] Preferably, the first end of the piston rod is a ball head, and a bushing is provided on the piston, with the ball head connected to the bushing.

[0009] Furthermore, the second end of the piston rod is threadedly connected to the first end of the adjusting rod, and the second end of the adjusting rod is threadedly connected to the first end of the drive rod.

[0010] Preferably, the adjusting rod is provided with a locking nut, which locks the adjusting rod and the driving rod.

[0011] Furthermore, the threaded section of the drive rod is provided with graduations.

[0012] Preferably, an extension rod is provided between the adjusting rod and the piston rod, and the extension rod is threadedly connected to the adjusting rod and the piston rod respectively.

[0013] Preferably, the cylinder block is equipped with a temperature sensor and a dynamic pressure sensor.

[0014] The present invention also provides a method for adjusting the compression ratio of a combustion chamber, the combustion chamber including the extension rod, wherein the compression ratio y is: y=(H+x) / x, Where x is the scale value of the thread on the drive rod, with the starting point near the piston rod as the 0 scale point; H is the theoretical compression stroke of the piston.

[0015] The present invention also provides another method for adjusting the compression ratio of a combustion chamber, wherein the combustion chamber does not include the extension rod, and the compression ratio y is: y = (H + L' + x) / (L' + x), Where x is the scale value of the thread on the drive rod, with the starting point near the piston rod as the 0 scale point; H is the theoretical compression stroke of the piston; L' is the remaining length of the compression chamber after the piston is fully compressed when the threaded end of the adjusting rod is placed at the 0 scale point of the drive rod.

[0016] The present invention has at least the following beneficial technical effects: The continuously adjustable compression ratio combustion chamber of this invention achieves continuous adjustment of the compression ratio by continuously adjusting the initial piston position through an adjusting rod and a driving rod. The adjusting rod for adjusting the length is located outside the cylinder block, where the temperature is close to room temperature and does not interfere with the combustion chamber, thus eliminating the need for cylinder disassembly and greatly improving adjustment efficiency. By setting an extension rod, the continuous adjustment range of the initial piston position is significantly increased, thereby expanding the range of continuous compression ratio adjustment. By setting a scale value on the driving rod, the compression ratio can be accurately calculated, and the connection position between the driving rod and the adjusting rod can be quickly determined by giving a compression ratio, greatly improving experimental efficiency.

[0017] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a combustion chamber structure with continuously adjustable compression ratio according to an embodiment of the present invention; Figure 2 This is a schematic diagram of compression ratio adjustment according to an embodiment of the present invention.

[0019] In the diagram, 1-drive rod, 2-locking nut, 3-adjusting rod, 4-extension rod, 5-piston rod, 6-bulb, 7-piston, 8-cylinder block, 9-temperature sensor, 10-cylinder head, 11-dynamic pressure sensor. Detailed Implementation

[0020] The preferred embodiments of the present invention are described below to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0021] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0022] This invention provides a combustion chamber with continuously adjustable compression ratio. By continuously adjusting the piston rod length, the initial piston position can be continuously adjusted, thereby achieving continuous adjustment of the compression ratio. Compared to existing discrete numerical adjustments that change the cylinder geometry, this invention achieves a leap from discrete to continuous, and from finite to infinite, in the compression ratio adjustment of a fast compressor.

[0023] like Figure 1 As shown, the combustion chamber with continuously adjustable compression ratio in this embodiment includes a cylinder block 8, a piston 7, a piston rod 5, an adjusting rod 3, and a drive rod 1.

[0024] The cylinder block 8 has an internal cavity to accommodate the piston 7; one end of it is provided with a cylinder head 10, which is sealed to the end of the cylinder block 8, so that a sealed compression chamber is formed between the piston 7 and the cylinder head 10, thereby realizing the compression of the gas in this area.

[0025] The piston 7 is located within the cavity of the cylinder block 8 and can move along the cavity. The outer edge of the piston 7, perpendicular to the direction of movement, forms a sealing structure with the inner wall of the cylinder block 8, thus creating a compression zone between the piston 7 and the cylinder head 10. The compression process is completed by the movement of the piston 7 within the cylinder block 8 towards the cylinder head 10.

[0026] The cylinder block 8 is typically a cylindrical structure, and correspondingly, the piston 7 is cylindrical. The inner diameter of the cylinder block 8 is 0.5-1mm larger than the outer diameter of the piston 7, and the wall thickness of the cylinder block 8 is 10-40mm, with the inner wall being ground. The outer diameter of the piston 7 is 50-100mm, and the material can be aluminum alloy.

[0027] The outer edge of the piston 7 is machined with a sealing groove, a guide groove, and a clearance groove. The sealing groove is used to seal the piston 7 with the inner wall of the cylinder block 8; the guide groove is used to guide the piston 7 when it moves inside the cylinder block 8, thereby reducing the probability of cylinder scoring; the clearance groove is used to absorb the boundary layer eddies in the combustion chamber and maintain the consistency of the flow field and temperature field in the combustion chamber.

[0028] The first end of the piston rod 5 is connected to the piston 7, and the second end of the piston rod 5 extends to the outside of the cylinder block 8 in a direction away from the cylinder head 10. The piston rod 5 drives the piston 7 to move inside the cylinder block 8.

[0029] In this embodiment, the first end of the piston rod 5 is a ball head, and the piston 7 is provided with a bushing 6. The ball head of the piston rod 5 is connected to the bushing 6. Through the ball head of the piston rod 5 and the bushing 6, the piston rod 5 can rotate freely relative to the piston 7. The bushing 6 can be made of brass and has an internal opening to mate with the ball head of the piston rod 5.

[0030] The first end of the adjusting rod 3 is detachably connected to the second end of the piston rod 5. The first end of the drive rod 1 is connected to the second end of the adjusting rod 3. The drive rod 1 is driven by an external drive device, and the motion is transmitted to the piston 7 via the adjusting rod 3 and the piston rod 5, thus enabling the piston 7 to move within the cylinder block 8. The connection length between the drive rod 1 and the adjusting rod 3 is adjustable and continuously adjustable. This allows for continuous adjustment of the initial position of the piston 7 within the cylinder block 8 while maintaining the connection position between the drive rod 1 and the external drive device, thereby adjusting the compression ratio of the cylinder block 8 continuously.

[0031] Specifically, the connection between the adjusting rod 3 and the piston rod 5 can be a threaded connection. An external thread is provided at the second end of the piston rod 5, and an internal thread is provided at the first end of the adjusting rod 3. The detachable connection between the adjusting rod 3 and the piston rod 5 is achieved through the meshing of the external thread and the internal thread.

[0032] The connection between the drive rod 1 and the adjusting rod 3 can also be a threaded connection. An external thread is provided at the second end of the adjusting rod 3, and an internal thread is provided at the first end of the drive rod 1. By meshing the external thread and the internal thread and changing the meshing length, the connection length between the drive rod 1 and the adjusting rod 3 can be adjusted.

[0033] To facilitate the adjustment of the thread engagement length between the drive rod 1 and the adjusting rod 3, a scale is provided on the threaded section of the drive rod 1. The starting point of the thread on the side of the drive rod 1 closest to the piston rod 5 is designated as the 0 mark, and the scale value gradually increases along the direction away from the piston rod 5. Thus, the thread engagement length between the adjusting rod 3 and the drive rod 1 can be directly read from the scale value. To facilitate observation of the position where the adjusting rod 3 engages with the drive rod 1, a rectangular opening is provided axially on the threaded section at the first end of the drive rod 1. The depth of the rectangular opening penetrates the wall of the drive rod 1. The scale value can be located on both sides of the rectangular opening, allowing direct reading after observing the end position of the adjusting rod 3 through the rectangular opening.

[0034] A locking nut 2 can be installed on the adjusting rod 3. After the adjusting rod 3 and the drive rod 1 are positioned, the drive rod 1 is locked by the locking nut 2, so that the adjusting rod 3 cannot rotate relative to the drive rod 1, thereby fixing the compression ratio.

[0035] An extension rod 4 can be added between the adjusting rod 3 and the piston rod 5. The extension rod 4 is also connected to the adjusting rod 3 and the piston rod 5 by a thread. By setting the extension rod 4, the initial position of the piston 7 can be significantly changed, expanding the range of continuous adjustment of the compression ratio.

[0036] In other embodiments, a temperature sensor 9 is embedded in the outer wall of the cylinder block 8 for measuring the initial temperature before compression; the temperature sensor 9 can be a K-type or PT-100 thermocouple with a diameter not exceeding 3mm. A dynamic pressure sensor 11 can be installed on the cylinder head 10 for measuring transient pressure changes in the compression chamber; the dynamic pressure sensor 11 is connected to the cylinder head 10 by threads, and its head is flush with the inner wall surface of the cylinder head 10.

[0037] like Figure 2 As shown, the compression ratio adjustment method of the continuously adjustable combustion chamber of the present invention is as follows.

[0038] When extension rod 4 is set, the threaded end of adjustment rod 3 is placed at the 0 mark of drive rod 1. The length of compression chamber before compression is equal to the theoretical compression stroke H. At this time, the theoretical compression ratio is infinite. When adjustment rod 3 is engaged with drive rod 1 to mark x, the compression ratio y at this time is: y=(H+x) / x. Without the extension rod 4, under the same structural dimensions, due to the lack of the effective length L of the extension rod 4, when the threaded end of the adjusting rod 3 is placed at the 0 mark of the driving rod 1, the length of the compression chamber before compression is H+L, and the length of the compression chamber after compression is L, that is, the remaining length L' of the compression chamber = L; when the adjusting rod 3 is engaged with the driving rod 1 to mark x, the compression ratio y at this time is: y = (H+L+x) / (L+x). The effective length L of the extension rod 4, that is, the increased distance between the adjusting rod 3 and the driving rod 1 after the extension rod 4 is added, is not exactly equal to the length of the extension rod 4 itself, considering the thread engagement.

[0039] Based on the above relationship, by adjusting the connection length between the adjusting rod 3 and the driving rod 1, the x value can be changed, thereby changing the compression ratio y and realizing continuous adjustment of the compression ratio.

[0040] The continuously adjustable compression ratio combustion chamber of this invention achieves continuous adjustment of the piston initial position and thus continuous adjustment of the compression ratio through a meshing threaded mechanism for continuous adjustment of the piston rod length. The adjusting rod for length adjustment is located outside the cylinder block, where the temperature is close to room temperature and does not interfere with the combustion chamber, thus eliminating the need for cylinder disassembly and greatly improving adjustment efficiency. By setting an extension rod, the continuous adjustment range of the piston initial position is significantly increased, thereby expanding the range of continuous compression ratio adjustment. By setting a scale value on the drive rod, the compression ratio can be accurately calculated, and the connection position between the drive rod and the adjusting rod can be quickly determined by a given compression ratio, greatly improving experimental efficiency.

[0041] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A combustion chamber with continuously adjustable compression ratio, characterized in that, include: The cylinder block has an internal cavity; A piston is disposed within the cavity and is capable of moving along the cavity. The outer edge of the piston, perpendicular to the direction of movement, is sealed to the inner wall of the cavity. A piston rod, the first end of which is connected to the piston, and the second end of which extends out of the cavity; An adjusting rod, the first end of which is detachably connected to the second end of the piston rod; A drive rod, the first end of which is connected to the second end of the adjusting rod, wherein the connection length between the drive rod and the adjusting rod is adjustable; The end of the cylinder block away from the piston rod is sealed.

2. The combustion chamber with continuously adjustable compression ratio as described in claim 1, characterized in that, The piston has a sealing groove, a guide groove, and a clearance groove on its outer edge.

3. The combustion chamber with continuously adjustable compression ratio as described in claim 1, characterized in that, The first end of the piston rod is a ball head, and a bushing is provided on the piston, with the ball head connected to the bushing.

4. The combustion chamber with continuously adjustable compression ratio as described in claim 1, characterized in that, The second end of the piston rod is threadedly connected to the first end of the adjusting rod, and the second end of the adjusting rod is threadedly connected to the first end of the drive rod.

5. The combustion chamber with continuously adjustable compression ratio as described in claim 4, characterized in that, The adjusting rod is equipped with a locking nut, which locks the adjusting rod and the driving rod together.

6. The combustion chamber with continuously adjustable compression ratio as described in claim 4, characterized in that, The threaded section of the drive rod is provided with a scale.

7. The combustion chamber with continuously adjustable compression ratio as described in claim 6, characterized in that, An extension rod is provided between the adjusting rod and the piston rod, and the extension rod is threadedly connected to the adjusting rod and the piston rod respectively.

8. The combustion chamber with continuously adjustable compression ratio as described in claim 1, characterized in that, The cylinder block is equipped with a temperature sensor and a dynamic pressure sensor.

9. A method for adjusting the compression ratio, used for adjusting the compression ratio of a combustion chamber as described in claim 7, characterized in that, The compression ratio y is: y=(H+x) / x, Where x is the scale value of the thread on the drive rod, with the starting point near the piston rod as the 0 scale point; H is the theoretical compression stroke of the piston.

10. A method for adjusting the compression ratio, used for adjusting the compression ratio of a combustion chamber as described in claim 6, characterized in that, The compression ratio y is: y = (H + L' + x) / (L' + x), Where x is the scale value of the thread on the drive rod, with the starting point near the piston rod as the 0 scale point; H is the theoretical compression stroke of the piston; L' is the remaining length of the compression chamber after the piston is fully compressed when the threaded end of the adjusting rod is placed at the 0 scale point of the drive rod.

Images