Structure for reducing emission during cold start of engine and use method of structure

Abstract

The invention discloses a structure for reducing emission during cold start of an engine and a using method of the structure, and relates to the field of engine emission, the structure comprises a timing wheel and an adjusting shaft assembly, the adjusting shaft assembly is installed on one side of the timing wheel, the adjusting shaft assembly comprises an outer rotor fixedly installed on one side of the timing wheel, the interior of the outer rotor is divided into a plurality of cavities, and the cavities are communicated with the timing wheel. The inner rotor is fixedly installed on the cam shaft and provided with a plurality of blades, and the cavity of the outer rotor is matched with the blades of the inner rotor to form a plurality of oil pressure cavities. The outer rotor is connected with the inner rotor in a sliding mode, and the engine ECU controls inlet and outlet of engine oil in the oil pressure cavity to control the relative position of the timing wheel and the cam shaft, so that the phase position of the cam shaft is controlled, and the opening moment of an engine valve is further controlled. According to the structure for reducing emission during cold start of the engine and the using method of the structure, when the engine is started, a motor drives the engine to rotate, and before an oil injection system works, a catalyst is heated to about 200 DEG C or above through high-temperature gas generated through compression of the engine, the ignition time of the catalyst is greatly shortened after the engine works, and the emission reduction effect is greatly improved. And about 60% of starting emission can be reduced.

Description

Technical Field

[0001] The invention relates to an engine cold start technology, and in particular to a structure for reducing emissions during engine cold start and a method for using the structure. Background Art

[0002] Automobile emission regulations are becoming more and more stringent. Modern automobile engines have higher and higher thermal efficiency, more and more precise air-fuel ratio control, and lower and lower original engine emissions. During automobile operation, the three-way catalytic converter is at normal operating temperature, and the conversion efficiency of the three-way catalytic converter is very high. The emission of toxic gases in automobile exhaust is very low. When the engine is cold-started, when the temperature of the three-way catalytic converter is lower than the ignition temperature (250 to 350 degrees Celsius), the conversion efficiency of the three-way catalytic converter is very low, and the content of toxic gases in the exhaust gas is very high at this time. Reducing cold-start emissions is the main direction to meet the new regulations, and one of the main directions to reduce cold starts is to shorten the ignition time of the three-way catalytic converter and quickly reach the working temperature of the three-way catalytic converter.

[0003] Commonly used methods to shorten the ignition time of the three-way catalytic converter include engine start calibration, delaying the ignition angle, increasing the exhaust temperature and electric heating of the catalyst.

[0004] The working principle of electric heating of the catalyst is: add a heating wire at the inlet of the three-way catalytic converter. When the engine is started, no fuel is injected. The exhaust gas is heated by the heating wire and then enters the three-way catalytic converter to heat the catalyst. After the temperature of the catalyst reaches the ignition temperature, the engine injects fuel and ignites.

[0005] In the prior art, the engine start calibration delays the ignition angle, increases the exhaust temperature, and accelerates the ignition of the catalyst. Before the catalyst is started, the untreated exhaust gas contains a large amount of emissions.

[0006] Electric heating of the catalyst increases costs, increases the space requirements for wiring harness layout, increases the risk of electromagnetic interference, and increases the risk of leakage. Summary of the invention

[0007] The object of the present invention is to provide a structure for reducing emissions during cold start of an engine and a method for using the structure to solve the above-mentioned deficiencies in the prior art.

[0008] In order to achieve the above-mentioned object, the present invention provides the following technical solution: a structure for reducing emissions during cold start of an engine, comprising a camshaft, an exhaust cam assembly being mounted on the camshaft, the exhaust cam assembly being movable on the camshaft, the exhaust cam assembly comprising a common cam and a large wrap angle cam, the wrap angle of the common cam being about 160°, and the wrap angle of the large wrap angle cam being about 30°-40° greater than that of the common cam, i.e., about 200°;

[0009] The exhaust cam assembly is symmetrically provided with a shift groove on the outside, a cross frame is provided above the shift groove, and the cross frame is installed with a solenoid valve assembly:

[0010] The solenoid valve assembly comprises:

[0011] The solenoid valve body is installed below the cross frame, and the outer side of the solenoid valve body is fixedly connected to the cross frame through which it passes. A shift guide rod is installed at the bottom of the solenoid valve body. The shift guide rod can extend to the inner side of the shift groove to drive the displacement of the exhaust cam assembly under the drive of the solenoid valve body.

[0012] Furthermore, it also includes:

[0013] A rocker arm, which is mounted on the bottom of the exhaust cam assembly;

[0014] The valve is installed on one side of the bottom of the rocker arm;

[0015] The tappet is installed on the other side of the bottom of the rocker arm;

[0016] The exhaust cam assembly can drive the rocker arm to drive the valve to move with the tappet as a fulcrum.

[0017] A method for reducing emissions during cold start of an engine, which is applicable to a structure for reducing emissions during cold start of an engine as claimed in any one of claims 1 to 2, comprises the following steps:

[0018] S1, the motor drives the engine to rotate, the injector and spark plug do not work, in the intake stroke, the piston moves downward, inhaling fresh air, in the compression stroke, the piston moves upward to compress the fresh air, and at the end of compression, the gas temperature in the cylinder can reach 700 degrees Celsius;

[0019] S2: The piston moves downward, the gas expands and does work on the piston, the temperature of the gas in the cylinder decreases, the exhaust valve opens in advance, the unexpanded high-temperature gas is discharged, and the outflowing high-temperature gas heats the catalyst;

[0020] S3. The exhaust VVT system intervenes to advance the timing of the ordinary cam in the exhaust cam assembly to its limit position, increase the average temperature of the exhaust gas, and heat the catalyst.

[0021] Furthermore, the step S3 can also be:

[0022] S31. When the engine is started, the solenoid valve body drives the shift guide rod to move downward to the inner side of the shift groove, pushing the exhaust cam assembly to move, so that the large wrap angle exhaust cam assembly is in the working position;

[0023] S32, the exhaust cam assembly is switched to a large wrap angle cam to increase the exhaust gas temperature and flow rate, shorten the catalyst heating time, and when the engine speed is about 1500rpm, the catalyst temperature can be increased to more than 200 degrees Celsius, and the ignition time is shortened by 60%-70%. Increasing the engine speed can further increase the exhaust temperature and thus shorten the ignition time;

[0024] S33. When the catalyst temperature rises to a stable value and no longer rises, the solenoid valve body drives the shift guide rod to move down to the inside of the shift groove, pushing the exhaust cam assembly to move, so that the ordinary cam is in the working position, the exhaust cam assembly switches to the ordinary cam, the injector and spark plug work, and the engine is started.

[0025] Furthermore, the step S3 can also be:

[0026] S311. A large wrap angle cam is arranged between two adjacent exhaust cam assemblies. The three cam surfaces correspond to the three rocker arms on the rocker shaft respectively. The lift of the large wrap angle cam is greater than that of the ordinary exhaust cam. When the engine is started, the piston of the rocker shaft in the hydraulically driven rocker shaft moves, so that the three rocker arms are connected as one. The large wrap angle cam in the middle drives the rocker arm to drive the valve to work, and the ordinary cams with smaller lift on both sides do not work, so that the high-temperature air compressed in the engine is discharged in advance to heat the catalyst. When the temperature of the catalyst rises to a stable value and no longer rises, the piston of the rocker shaft in the hydraulically driven rocker shaft moves, and the connection between the three rocker arms is disconnected. The rocker arms on both sides are driven by the ordinary cam to push the two exhaust valves respectively. At this time, the middle rocker arm performs invalid movement on the rocker shaft, and the engine starts.

[0027] Compared with the prior art, the present invention provides a structure for reducing emissions during cold start of an engine and a method of using the same. Before the engine injection system works, the catalyst is heated to about 200 degrees Celsius or more, which greatly shortens the catalyst ignition time after the engine works, and can reduce startup emissions by 60%. Compared with the electric heating catalyst solution, the present invention avoids the electric heating system, saves costs and space for wiring harness layout, avoids electromagnetic interference and leakage risks, and achieves catalyst heating without adding an electric heating device, thereby increasing the catalyst temperature when the engine starts, greatly shortening the time from engine ignition to catalyst ignition, and reducing engine emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1A first schematic diagram of the overall structure provided in Embodiment 1 of the present invention;

[0030] Figure 2 A second schematic diagram of the overall structure provided in Embodiment 1 of the present invention;

[0031] Figure 3 A schematic diagram of the overall structure provided for the second embodiment of the present invention;

[0032] Figure 4 A partial cross-sectional structural schematic diagram provided for Embodiment 2 of the present invention;

[0033] Figure 5 This is a working principle diagram of the VVT ​​variable valve timing system according to an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of the overall structural principle of the cam switching system provided in an embodiment of the present invention.

[0035] Description of reference numerals:

[0036] 1. Timing wheel; 3. Exhaust cam assembly; 31. Ordinary cam; 32. Large wrap angle cam; 4. Camshaft; 5. Valve; 6. Rocker arm; 7. Tappet; 8. Rocker shaft; 81. Rocker shaft piston; 9. Cross frame; 10. Solenoid valve assembly; 101. Solenoid valve body; 102. Shift guide rod; 41. Shift groove. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] Embodiment 1:

[0039] See also Figure 1-Figure 4 A structure for reducing emissions during cold start of an engine and a method for using the same, wherein an exhaust cam assembly 3 is mounted on a camshaft 4, the exhaust cam assembly 3 is movable on the camshaft 4, the exhaust cam assembly 3 comprises a common cam 31 and a large wrap angle cam 32, the wrap angle of the common cam 31 is about 160°, and the wrap angle of the large wrap angle cam 32 is about 30°-40° greater than that of the common cam 31, i.e., about 200°;

[0040] A displacement groove 41 is symmetrically provided on the outer side of the exhaust cam assembly 3, a cross frame 9 is provided above the displacement groove 41, and a solenoid valve assembly 10 is installed on the cross frame 9:

[0041] The solenoid valve assembly 10 comprises:

[0042] The solenoid valve body 101 is installed below the cross frame 9. The outer side of the solenoid valve body 101 is fixedly connected to the cross frame 9 at the penetration point. A shift guide rod 102 is installed at the bottom of the solenoid valve body 101. The shift guide rod 102 can extend to the inner side of the shift groove 41 to drive the displacement of the exhaust cam assembly 3 under the drive of the solenoid valve body 101.

[0043] Also includes:

[0044] A rocker arm 6, which is mounted at the bottom of the exhaust cam assembly 3;

[0045] The valve 5 is mounted on one side of the bottom of the rocker arm 6;

[0046] A tappet 7, which is mounted on the other side of the bottom of the rocker arm 6;

[0047] The exhaust cam assembly 3 can drive the rocker arm 6 to move the valve 5 with the tappet 7 as a fulcrum.

[0048] The specific implementation is as follows: the solenoid valve body 101 is electrically connected to an external power supply and is controlled by the engine control unit ECU. The solenoid valve body 101 can drive the shift guide rod 102 to move to the inside of the shift groove 41, and drive the exhaust cam assembly 3 to shift when the camshaft 4 rotates, so as to switch between the ordinary cam 31 and the large wrap angle cam 32, thereby switching the advance angle and exhaust flow of the engine exhaust.

[0049] Embodiment 2:

[0050] See also Figure 5 This embodiment provides a technical solution based on the first embodiment: the VVT ​​control system includes an outer rotor and an inner rotor, the interior of the outer rotor is divided into a plurality of cavities, the inner rotor is fixedly mounted on the camshaft 4, the inner rotor has a plurality of blades, the outer rotor cavities and the inner rotor blades cooperate to form a plurality of oil pressure chambers, the outer rotor is slidably connected with the inner rotor, and the relative position of the timing wheel 1 and the camshaft 4 is controlled by the engine ECU to control the inflow and outflow of the oil in the aforementioned oil pressure chambers, thereby controlling the phase of the camshaft 4 and further controlling the opening time of the engine valve.

[0051] Embodiment three:

[0052] See also Figure 1-Figure 6 This embodiment provides a technical solution based on the first and second embodiments: a method for reducing emissions during cold start of an engine, which is applicable to a structure for reducing emissions during cold start of an engine according to any one of claims 1 to 2, comprising the following steps:

[0053] S1, the motor drives the engine to rotate, the injector and spark plug do not work, in the intake stroke, the piston moves downward, inhaling fresh air, in the compression stroke, the piston moves upward to compress the fresh air, and at the end of compression, the gas temperature in the cylinder can reach 700 degrees Celsius;

[0054] S2, the piston moves downward, the gas expands and does work on the piston, the gas temperature in the cylinder decreases, the exhaust valve 5 opens in advance, the unexpanded high-temperature gas is discharged, and the outflowing high-temperature gas heats the catalyst;

[0055] S3. The exhaust VVT system intervenes to advance the timing of the ordinary cam 31 in the exhaust cam assembly 3 to its limit position, thereby increasing the average temperature of the exhaust gas and heating the catalyst.

[0056] Step S3 can also be:

[0057] S31, when the engine is started, the electromagnetic valve body 101 drives the shift guide rod 102 to move downward to the inner side of the shift groove 41, pushing the exhaust cam assembly 3 to move to the working position of the large wrap angle cam 32;

[0058] S32, the exhaust cam assembly 3 is switched to the large wrap angle cam 32, which increases the exhaust gas temperature and flow rate, shortens the catalyst heating time, and when the engine speed is about 1500rpm, the catalyst temperature can be increased to more than 200 degrees Celsius, and the ignition time is shortened by 60%-70%. Increasing the engine speed can further increase the exhaust temperature and thus shorten the ignition time;

[0059] S33, when the catalyst temperature rises to a stable value and no longer rises, the solenoid valve body 101 drives the shift guide rod 102 to move down to the inside of the shift groove 41, pushing the exhaust cam assembly 3 to move to the working position of the ordinary cam 31, the exhaust cam assembly 3 switches to the ordinary cam 31, the injector and the spark plug work, and the engine is started.

[0060] Step S3 can also be:

[0061] S311, the large wrap angle cam 32 is set between two adjacent exhaust ordinary cams 31, and the three cam surfaces correspond to the three rocker arms 6 on the rocker shaft 8 respectively. The lift of the large wrap angle cam 32 is greater than the lift of the ordinary cam 31. When the engine starts, the rocker shaft piston 81 in the hydraulic drive rocker shaft 8 moves, so that the three rocker arms 6 are connected as one, and the middle large wrap angle cam 32 drives the rocker arm 6 to drive the valve 5 to work, and the ordinary cams 31 on both sides with smaller lifts do not work, so that the high-temperature air compressed in the engine is discharged in advance to heat the catalyst. When the temperature of the catalyst rises to a stable value and no longer rises, the connection between the three rocker arms 6 is disconnected, and the rocker arms 6 on both sides are driven by the ordinary cam 31 to push the two exhaust valves 5 respectively. At this time, the middle rocker arm 6 performs invalid movement on the rocker shaft 8, and the engine starts.

[0062] The above description is only by way of illustration of certain exemplary embodiments of the present invention, and the principles of the present invention may also be implemented with other forms of valve drive mechanisms and cam switching systems. Needless to say, those skilled in the art may modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A structure for reducing emissions during cold start of an engine, comprising a camshaft (4), characterized in that: An exhaust cam assembly (3) is mounted on the camshaft (4), and the exhaust cam assembly (3) is movable on the camshaft (4). The exhaust cam assembly (3) comprises a common cam (31) and a large wrap angle cam (32). The wrap angle of the common cam (31) is about 160°, and the wrap angle of the large wrap angle cam (32) is about 30°-40° larger than that of the common cam (31), i.e., about 200°. The exhaust cam assembly (3) is symmetrically provided with a displacement groove (41), a cross frame (9) is arranged above the displacement groove (41), and the cross frame (9) is installed with a solenoid valve assembly (10): The solenoid valve assembly (10) comprises: The electromagnetic valve body (101) is installed below the cross frame (9), and the outer side of the electromagnetic valve body (101) is fixedly connected to the cross frame (9) at the penetration point. A shift guide rod (102) is installed at the bottom of the electromagnetic valve body (101). The shift guide rod (102) can extend to the inner side of the shift groove (41) under the drive of the electromagnetic valve body (101) to drive the displacement of the exhaust cam assembly (3).

2. The structure for reducing emissions during cold start of an engine according to claim 1, characterized in that: Also includes: A rocker arm (6) mounted on the bottom of the exhaust cam assembly (3); A valve (5) mounted on one side of the bottom of the rocker arm (6); A tappet (7) mounted on the other side of the bottom of the rocker arm (6); The exhaust cam assembly (3) can drive the rocker arm (6) to drive the valve (5) to move with the tappet (7) as a fulcrum.

3. A method for reducing emissions during cold start of an engine, which is applicable to a structure for reducing emissions during cold start of an engine as claimed in any one of claims 1 to 2, characterized in that: The steps include: S1, the motor drives the engine to rotate, the injector and spark plug do not work, in the intake stroke, the piston moves downward, inhaling fresh air, in the compression stroke, the piston moves upward to compress the fresh air, and at the end of compression, the gas temperature in the cylinder can reach 700 degrees Celsius; S2, the piston moves downward, the gas expands and does work on the piston, the temperature of the gas in the cylinder decreases, the exhaust valve (5) opens in advance, the unexpanded high-temperature gas is discharged, and the outflowing high-temperature gas heats the catalyst; S3, the exhaust VVT variable valve timing system intervenes to advance the timing of the ordinary cam (31) in the exhaust cam assembly (3) to the limit position, thereby increasing the average temperature of the exhaust gas and heating the catalyst.

4. The method for reducing emissions during cold start of an engine according to claim 3, characterized in that: The step S3 comprises: S31, when the engine is started, the electromagnetic valve body (101) drives the shift guide rod (102) to move downward to the inner side of the shift groove (41), pushing the exhaust cam assembly (3) to move, so that the large wrap angle exhaust cam assembly (32) is in the working position; S32, the exhaust cam assembly (3) is switched to a large-wrapped-angle exhaust cam assembly (32), so as to increase the exhaust gas temperature and flow rate and shorten the catalyst heating time. When the engine speed is about 1500 rpm, the catalyst temperature can be increased to about 200 degrees Celsius or more, and the ignition time can be shortened by 60%-70%. Increasing the engine speed can further increase the exhaust temperature and thus shorten the ignition time. S33, when the catalyst temperature rises to a stable value and does not rise any more, the electromagnetic valve body (101) drives the shift guide rod (102) to move downward to the inner side of the shift groove (41), pushing the exhaust cam assembly (3) to move so that the ordinary cam (31) is in the working position, the exhaust cam assembly (3) switches to the ordinary cam (31), the VVT ​​adjusts the phase of the exhaust cam assembly to the normal position, the injector and the spark plug work, and the engine is started.

5. The structure for reducing emissions during cold start of an engine and the method for using the same according to claim 3, characterized in that: The step S3 comprises: S311, a large wrap angle cam (32) is arranged between two adjacent exhaust ordinary cams (31), and the three cam surfaces correspond to the three rocker arms (6) on the rocker shaft (8), and the lift of the large wrap angle cam is greater than the lift of the ordinary exhaust cam. When the engine is started, the rocker shaft piston (81) in the hydraulically driven rocker shaft (8) moves, so that the three rocker arms (6) are connected as one, and the middle large wrap angle cam (32) drives the rocker arm (6) to drive the valve (5) to work, and the ordinary cams (31) with smaller lift on both sides do not work, so that the high-temperature air compressed in the engine is discharged in advance to heat the catalyst. When the temperature of the catalyst rises to a stable value and does not rise any more, the rocker shaft piston (81) in the hydraulically driven rocker shaft (8) moves, so that the three rocker arms (6) are connected and disconnected, and the rocker arms (6) on both sides are driven by the ordinary cam (31) to push the two exhaust valves (5) respectively. At this time, the middle rocker arm (6) performs an invalid movement on the rocker shaft (8), and the engine starts.

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