CN106996346B - Automatic variable compression ratio engine piston - Google Patents
Automatic variable compression ratio engine piston Download PDFInfo
- Publication number
- CN106996346B CN106996346B CN201710009156.XA CN201710009156A CN106996346B CN 106996346 B CN106996346 B CN 106996346B CN 201710009156 A CN201710009156 A CN 201710009156A CN 106996346 B CN106996346 B CN 106996346B
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- piston
- compression ratio
- piston head
- skirt
- piston skirt
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/0015—Multi-part pistons
- F02F3/003—Multi-part pistons the parts being connected by casting, brazing, welding or clamping
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
- F02B75/044—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of an adjustable piston length
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/28—Other pistons with specially-shaped head
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
The invention discloses an automatic variable compression ratio engine piston, which is characterized in that: the piston comprises a piston head and a piston skirt, wherein the piston head and the piston skirt are movably connected through a limiting baffle, the relative displacement between the piston head and the piston skirt is limited through the limiting baffle, and a compression spring is arranged between the piston head and the piston skirt. The damping type variable compression ratio piston can automatically change the compression ratio, not only can improve the partial load thermal efficiency of the gasoline engine, but also can avoid knocking at full load, and effectively improves the reliability and the economical efficiency of the engine. The fuel consumption of the engine is reduced by 5-7% compared with that of an engine with a fixed compression ratio through simulation calculation in a fuel consumption test (NEDC) cycle of a passenger car; compared with variable compression ratio engines with other structures, the production cost is reduced by 30-80%.
Description
Technical Field
The invention belongs to the technical field of internal combustion engines, and particularly relates to an automatic variable compression ratio engine piston.
Background
The compression ratio of the existing gasoline engine is fixed, the partial load thermal efficiency can be improved by increasing the compression ratio, and the fuel consumption is reduced; but the risk of knocking in a high-load area exists when the compression ratio is improved, the invention automatically changes the compression ratio through the damping type variable compression ratio piston, can simultaneously meet the work of high load and low load of the gasoline engine, can improve the thermal efficiency of the gasoline engine and can also effectively prevent knocking. The compression ratio of the combustion chamber of a specific engine is variable but cannot be automatically changed, the structure is complex, the control is difficult, the cost is high, and the mass production is not realized.
Disclosure of Invention
The invention aims to provide a damping type variable compression ratio piston which can automatically change the compression ratio, improve the partial load thermal efficiency of a gasoline engine, avoid knocking at full load and effectively improve the reliability and the economical efficiency of an engine aiming at the defects of the existing gasoline engine with a fixed compression ratio.
In order to achieve the purpose, the invention adopts the following technical scheme:
an automatic variable compression ratio engine piston characterized by: the piston comprises a piston head and a piston skirt, wherein the piston head and the piston skirt are movably connected through a limiting baffle, the relative displacement between the piston head and the piston skirt is limited through the limiting baffle, and a compression spring is arranged between the piston head and the piston skirt; the compression ratio is automatically changed by the interaction of the compression pressure of the air in the compression stroke of the cylinder and the elastic force of the compression spring.
The working mode that the compression ratio is automatically variable is realized in the compression stroke; when the engine is in a low-load working condition, the air intake is less, the compression pressure of air in a compression stroke is smaller, the compression spring is in a smaller compression position, the compression height of the piston is larger, a high-compression-ratio working mode can be realized, and the heat efficiency is improved; when the engine is under a large load or full load working condition, the air inflow is large, the compression pressure of air in a compression stroke is large, the compression spring is located at a large compression position, the compression height of the piston is small, the working mode with a low compression ratio can be realized, and the engine can be prevented from knocking.
The piston comprises a piston skirt, a piston head and a compression spring, wherein the compression spring is arranged between the piston skirt and the piston head, the compression spring is multiple, the top surface of the piston skirt and the top of an inner cavity of the piston head are provided with a plurality of hollow annular bosses, and the compression spring is arranged between the piston skirt and the bosses of the piston head.
Preferably: the compression springs are cylindrical spiral compression springs, the number of the compression springs is 5, and the compression springs are uniformly distributed between the piston head and the piston skirt. The compression spring may also be a wave spring.
It is further characterized in that: damping parts are arranged between the piston skirt and the limiting baffle and between the limiting baffle and the piston head.
The damping part is one or the combination of two of an open annular damping part, a wave spring and a disc spring.
The damping part can also be an annular damping cavity which is formed by the outer wall of the piston skirt part, the inner wall of the piston head part and the upper end face of the limiting baffle.
Further: the piston is characterized in that the side wall of the upper part of the piston head is provided with a ring groove, the side wall of the lower part of the piston head is provided with guide surfaces at two sides, and weight-reducing gaps are arranged at two sides of each guide surface.
The piston skirt comprises a top step, a neck step and a lower step, the neck step is connected with the top step and the lower step, and the diameter of the neck step is smaller than that of the top step and the lower step; the side wall of the lower step is provided with two arc-shaped guide surfaces, two opposite planes are arranged on two sides of each arc-shaped guide surface, and pin holes are formed in the planes.
The limiting blocking pieces are two arc-shaped blocking pieces and are clamped on the neck step of the piston skirt portion after being fixedly connected with the bottom surface of the piston head portion, and the piston head portion and the limiting blocking pieces are limited to slide between the top surface of the lower step of the piston skirt portion and the bottom surface of the top step.
A rectangular clamping groove is formed in the inner wall of the inner cavity of the piston head, and a rectangular bulge is formed in the outer wall of the step at the upper part of the piston skirt; the rectangular clamping groove is matched with the rectangular protrusion to guide the relative displacement of the piston head and the piston skirt.
And oil holes are radially formed in the inner wall of the pin hole in the step at the lower part of the piston skirt part.
The relative displacement distance between the piston head and the piston skirt is 0-5 mm.
The damping type variable compression ratio piston can automatically change the compression ratio, not only can improve the partial load thermal efficiency of the gasoline engine, but also can avoid knocking at full load, and effectively improves the reliability and the economical efficiency of the engine. The fuel consumption of the engine is reduced by 5-7% compared with that of an engine with a fixed compression ratio through simulation calculation in a fuel consumption test (NEDC) cycle of a passenger car; compared with variable compression ratio engines with other structures, the production cost is reduced by 30-80%.
Drawings
FIG. 1 is a schematic view of the separation structure of the present invention.
Fig. 2 and 3 are schematic top views of the piston.
Fig. 4 and 5 are schematic views of the piston skirt.
Fig. 6 is a schematic view of a compression spring.
Fig. 7 is a schematic view of a limiting block sheet.
FIG. 8 is a schematic diagram of the piston at highest compression ratio.
Fig. 9 is a schematic view showing a state of lowest compression ratio of the piston.
Fig. 10 is a schematic view showing a state of lowest compression ratio of the piston.
FIG. 11 is a schematic view of the upper damping member installation.
Detailed Description
The engine piston shown in fig. 1 is designed into an upper part and a lower part which can slide relatively: a piston head 100 and a piston skirt 200. And 5 (the number can be adjusted according to specific conditions) compression springs 300 are uniformly distributed between the piston top 100 and the piston skirt 200 on the circumference and the circle center, and limit baffles 400 are welded on the compression springs. An upper damping member 500 and a lower damping member 600 are respectively disposed between the piston skirt 200 and the stopper 400, and between the stopper 400 and the piston head 100.
As shown in fig. 2 and 3, the piston head 100 includes 5 bosses 101 for mounting the compression spring 300, which can prevent the compression spring 300 from radially displacing, the bosses 101 are dug with small holes 103 for reducing the weight of the piston head 100, and the bosses 101 have a structure with a large bottom and a small upper portion, which is convenient for mounting the spring. The inner wall of the inner cavity of the piston head 100 is provided with a rectangular clamping groove 102, and as shown in fig. 4, the outer wall of the upper step of the piston skirt 200 is provided with a rectangular protrusion 203. The rectangular clamping groove 102 is a guide groove of the rectangular protrusion 203 of the skirt portion, and the rectangular clamping groove 102 of the piston head portion 100 and the rectangular protrusion 203 of the piston skirt portion 200 are matched with each other, so that good guiding of the piston head portion 100 and the piston skirt portion 200 can be achieved, and relative rotation of the piston head portion 100 and the piston skirt portion 200 can be prevented. The piston head 100 has a ring groove 108 on the upper side wall, the piston head 100 has a guide surface 106 on both sides of the lower side wall, and the guide surface 106 has a weight-reducing notch 105 on both sides to reduce the weight of the piston head 100. The guide surface 106 not only ensures good guidance of the piston during movement, but also effectively prevents the piston head 100 from rolling.
The upper and lower parts of the damping member are preferably open-ended annular shock absorbing members as shown in fig. 10, in order to prevent the piston head 100 from rapidly axially sliding relative to the piston skirt 200 when the compression ratio is rapidly changed, and the limit stop piece 400 welded with the piston head 100 impacts the limit surface of the piston skirt 200 to generate noise, vibration and even damage to the mechanical structure. The upper damping member 500 is installed between the neck step 210 of the piston skirt 200 and the upper plane 402 of the stopper flap 400, and the lower damping member 600 is installed between the lower step 207 of the piston skirt 200 and the lower plane 403 of the stopper flap 400. The damping member may be a wave spring, a disc spring, or any other type of high temperature resistant elastomeric material or resilient structure. The upper damping part 500 is installed in an annular cavity 501 (as shown in fig. 11) formed by the piston head 100, the piston skirt 200 and the limiting baffle 400, and a nozzle can be used for injecting engine oil to replace an elastic structure for damping in the cavity to play a buffering role, and at the moment, an oil drainage hole is formed in the limiting baffle 400.
As shown in fig. 4 and 5, the piston skirt 200 includes 5 bosses 202 for mounting the compression springs 300, and the 5 bosses 202 of the piston skirt 200 are connected to the 5 bosses 101 of the piston head 100 through the compression springs 300. The middle small hole 201 is used for reducing the weight of the piston skirt 200, and the rectangular protrusion 203 is matched with the rectangular clamping groove 102 of the piston head 100 to prevent the piston head 100 and the piston skirt 200 from rotating relatively. The piston skirt 200 comprises a top step, a neck step 210 and a lower step 207, the neck step 210 connects the top step and the lower step 207, the neck step 210 is smaller in diameter than the top step and the lower step 207; the side wall of the lower step 207 is provided with two arc-shaped guide surfaces 204, two sides of each arc-shaped guide surface 204 are two opposite planes, and the planes are provided with pin hole reticulate patterns 205 to enhance the rigidity of the piston skirt portion 200 and reduce the weight. The plane has a pin hole 206 for fitting a small end of a connecting rod. The upper surface of the lower step 207 serves to limit the distance that the piston head 100 moves downward from the limit stop 400. An oil hole 208 is radially provided in an inner wall of the pin hole 206, and the oil hole 208 is used for lubrication between the piston pin and the hole. A concave hole 209 is formed above the oil hole 208, and the concave hole 209 is used for reducing the weight of the piston skirt portion 200.
The compression spring 300 is uniformly installed between the piston head 100 and the piston skirt 200, and preferably, a wave-shaped compression spring as shown in fig. 6 is used to reduce the height of the spring, and any other type of spring such as a disc spring, a helical coil spring, etc. may be used. The spring stiffness needs to be designed strictly, can resist the impact of the explosion pressure in the cylinder, and can be automatically compressed or extended according to the pressure change in the cylinder, so that the compression height of the piston is changed. The steel wire 301 of the compression spring 300 must have good thermal stability. When the compression spring 300 is installed between the piston head 100 and the piston skirt 200, there is a certain amount of pre-compression, which also needs to be strictly designed, and the top and bottom surfaces of the spring contacting the piston head 100 and the piston skirt 200 may be flat or curved.
As shown in fig. 1 and 7, the limit stop 400 is two arc-shaped stop plates, two semicircular limit stop plates 400 are welded by laser, and the whole limit stop plate is welded on the bottom surface 107 of the piston head 100 and clamped on the neck step 210 of the piston skirt to limit the piston head 100 and the limit stop plate 400 from sliding between the top surface of the lower step 210 and the bottom surface of the top step of the piston skirt 200. The piston head 100 is prevented from being separated from the piston skirt 200 in the movement process, the protruding part 401 at the edge of the limiting baffle 400 increases the strength and the limiting area of the limiting baffle 400, and the limiting baffle is prevented from being damaged in the operation process.
When the engine is in a low-load working condition, the compression pressure of air in a compression stroke cylinder is smaller, the compression spring 300 is positioned at a smaller compression position, and the compression height of the piston is larger, so that high compression ratio can be realized, the heat efficiency is improved, and the fuel consumption rate is reduced; when the engine is under a large load or full load working condition, the compression pressure of air in the compression stroke cylinder is large, the compression spring 300 is located at a large compression position, the compression height of the piston is small, the low compression ratio can be realized, and the knocking is prevented. The relative displacement between the piston head 100 and the piston skirt 200 is 0 mm-5 mm.
The free state of the piston is shown in fig. 8, the piston is at the maximum compression height position, the relative displacement between the piston head 100 and the piston skirt 200 is 0mm, and the compression ratio of the gasoline engine is maximum at the moment; FIG. 8 is an intermediate state compression ratio state; the maximum compression state of the piston is shown in fig. 10, the piston is at the minimum compression height position, the relative displacement between the piston head 100 and the piston skirt 200 is 5mm, and the compression ratio of the gasoline engine is at the minimum.
When the gasoline engine runs at a lower load, the compression pressure of air in a compression stroke cylinder is smaller, the pre-compression force of the cylindrical spiral compression spring 300 can resist the compression pressure of the air in the cylinder without being further compressed, the piston is in a maximum compression height state, and as shown in fig. 8, a limiting baffle 400 welded on the piston head 100 is limited by the neck platform 210 of the piston skirt 200; along with the increase of the load of the gasoline engine, the compression pressure of air in the cylinder is gradually increased, the compression spring 300 is gradually compressed, at the moment, the limiting baffle 400 moves between the top surface of the lower step 210 and the bottom surface of the top step of the piston skirt 200, the compression height of the piston is reduced, and the compression ratio begins to be reduced; when the gasoline engine runs at a high load or a full load, the compression pressure of air in the cylinder reaches the maximum, the compression spring 300 is further compressed, the piston is in a minimum compression height state, and the occurrence of knocking of the gasoline engine is effectively prevented, as shown in fig. 9, the limiting baffle 400 welded on the piston head 100 is limited by the upper surface of the lower step 207 of the piston skirt 200.
Claims (9)
1. An automatic variable compression ratio engine piston characterized by: the method is characterized in that: the piston skirt part is guided, and a compression spring is arranged between the piston head part and the piston skirt part; the compression ratio is automatically changed through the interaction of the compression pressure of air in the compression stroke of the air cylinder and the elastic force of the compression spring; damping parts are arranged between the piston skirt part and the limiting baffle plate and between the limiting baffle plate and the piston head part; the piston skirt comprises a top step, a neck step and a lower step, the neck step is connected with the top step and the lower step, and the diameter of the neck step is smaller than that of the top step and the lower step; the side wall of the lower step is provided with two arc-shaped guide surfaces, two opposite planes are arranged on two sides of each arc-shaped guide surface, and pin holes are formed in the planes; the limiting blocking pieces are two arc-shaped blocking pieces and are clamped on the neck step of the piston skirt portion after being fixedly connected with the bottom surface of the piston head portion, and the piston head portion and the limiting blocking pieces are limited to slide between the top surface of the lower step of the piston skirt portion and the bottom surface of the top step.
2. The automatic variable compression ratio engine piston according to claim 1, characterized in that: the piston comprises a piston skirt, a piston head and a compression spring, wherein the compression spring is arranged between the piston skirt and the piston head, the compression spring is multiple, the top surface of the piston skirt and the top of an inner cavity of the piston head are provided with a plurality of hollow annular bosses, and the compression spring is arranged between the piston skirt and the bosses of the piston head.
3. The automatic variable compression ratio engine piston according to claim 2, characterized in that: the compression springs are cylindrical spiral compression springs or wave springs, the number of the compression springs is 5, and the compression springs are uniformly distributed between the piston head and the piston skirt.
4. The automatic variable compression ratio engine piston according to claim 1, characterized in that: the damping part is one or the combination of two of an open annular damping part, a wave spring and a disc spring.
5. The automatic variable compression ratio engine piston according to any one of claims 1 to 3, characterized in that: and an annular damping cavity is defined by the outer wall of the piston skirt part, the inner wall of the piston head part and the upper end surface of the limiting baffle.
6. The automatic variable compression ratio engine piston according to claim 1, characterized in that: the piston is characterized in that the side wall of the upper part of the piston head is provided with a ring groove, the side wall of the lower part of the piston head is provided with guide surfaces at two sides, and weight-reducing gaps are arranged at two sides of each guide surface.
7. The automatic variable compression ratio engine piston according to claim 1, characterized in that: a rectangular clamping groove is formed in the inner wall of the inner cavity of the piston head, and a rectangular bulge is formed in the outer wall of the step at the upper part of the piston skirt; the rectangular clamping groove is matched with the rectangular protrusion, so that relative displacement of the piston head and the piston skirt is guided, and relative rotation between the piston head and the piston skirt is prevented.
8. The automatic variable compression ratio engine piston according to claim 1, characterized in that: and oil holes are radially formed in the inner wall of the pin hole in the step at the lower part of the piston skirt part.
9. The automatic variable compression ratio engine piston according to any one of claims 1 to 3, characterized in that: the relative displacement distance between the piston head and the piston skirt is 0-5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710009156.XA CN106996346B (en) | 2017-01-06 | 2017-01-06 | Automatic variable compression ratio engine piston |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710009156.XA CN106996346B (en) | 2017-01-06 | 2017-01-06 | Automatic variable compression ratio engine piston |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106996346A CN106996346A (en) | 2017-08-01 |
| CN106996346B true CN106996346B (en) | 2020-09-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201710009156.XA Active CN106996346B (en) | 2017-01-06 | 2017-01-06 | Automatic variable compression ratio engine piston |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110905763B (en) * | 2019-10-24 | 2021-07-20 | 浙江藤井空压机有限公司 | Air compressor machine of variable stroke |
| CN111425313A (en) * | 2020-03-20 | 2020-07-17 | 唐为民 | Combined piston with variable compression ratio |
| CN113982748B (en) * | 2021-11-17 | 2022-08-05 | 中国第一汽车股份有限公司 | Piston link assembly, engine and vehicle |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2431451A (en) * | 2005-10-20 | 2007-04-25 | George Frederic Galvin | Piston incorporating a disc spring made of a superelastic material |
| CN101387228A (en) * | 2008-09-02 | 2009-03-18 | 奇瑞汽车股份有限公司 | Engine with compression ratio variable piston |
| CN102364076A (en) * | 2011-11-11 | 2012-02-29 | 武汉理工大学 | Optimized variable compression ratio piston of internal-combustion engine |
| CN104179591A (en) * | 2014-08-12 | 2014-12-03 | 中南大学 | Piston structure capable of realizing variable compression ratio of engine |
| CN104500239A (en) * | 2014-10-20 | 2015-04-08 | 龙勇军 | Suspended type compression ratio variable device |
| CN105952547A (en) * | 2016-06-16 | 2016-09-21 | 徐州弦波引擎机械科技有限公司 | Length-variable engine piston |
-
2017
- 2017-01-06 CN CN201710009156.XA patent/CN106996346B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2431451A (en) * | 2005-10-20 | 2007-04-25 | George Frederic Galvin | Piston incorporating a disc spring made of a superelastic material |
| CN101387228A (en) * | 2008-09-02 | 2009-03-18 | 奇瑞汽车股份有限公司 | Engine with compression ratio variable piston |
| CN102364076A (en) * | 2011-11-11 | 2012-02-29 | 武汉理工大学 | Optimized variable compression ratio piston of internal-combustion engine |
| CN104179591A (en) * | 2014-08-12 | 2014-12-03 | 中南大学 | Piston structure capable of realizing variable compression ratio of engine |
| CN104500239A (en) * | 2014-10-20 | 2015-04-08 | 龙勇军 | Suspended type compression ratio variable device |
| CN105952547A (en) * | 2016-06-16 | 2016-09-21 | 徐州弦波引擎机械科技有限公司 | Length-variable engine piston |
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| CN106996346A (en) | 2017-08-01 |
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