The mainstream automatic start-stop method in the market is questioned because of the problem of service life and reliability. The setting of the Infiniti Q50 on-line steering system is a good testimony. Even with three sets of ECUs that are substitutes, the siege lions have a clutch between the steering column and the steering gear as the final card.
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However, in the automotive industry, there are always frequent events, and the odds are more common. There are always one or two that do not take the usual path.
For a general engine, the vehicle battery supplies power to the starter during starting, which drives the engine to rotate. For the automatic start-stop system, the engine is required to start faster. The most easy way to realize this is to use a larger torque and power starter and a more powerful battery. More complicated and reliable, it is fully automatic. The micro-mixing mode is stopped, and an additional motor and auxiliary battery are added.
But in fact, there are more articles to do during the engine start-up process. At the most basic, why does the engine need to be driven by the starter when starting? This is because the engine needs initial power, so that the piston of one of the cylinders can complete the intake and compression strokes, and then the ignition works. After that, the engine can start itself. The cycle no longer requires the power of the starter.
The reason why the starting process of the engine is slow is that the starting and compressing process cannot be lacked for each starting, and the other is because the starting machine and the engine also take time. Therefore, if the time of the two processes can be shortened or eliminated, the engine restart process time will be accelerated.
Mazda: The master of micro control
It seems that Mazda has been away from the mainstream automakers for a long time, both in terms of brand awareness and influence. However, this company with the name "Japan BMW" is a technical fanatic, like a rotor engine, and a second-generation Chuangchi blue sky engine that has to increase the compression ratio to 18.
The start-stop technology used on Mazda is called i-stop, and the i-stop technology is mainly for the first one mentioned above.
When the driver presses the brakes until the vehicle is completely stopped, the i-stop system automatically cuts off the oil supply and stops it completely, and precisely controls the position of the piston so that the piston of each cylinder is parked in the proper position as much as possible. Then select the most suitable cylinder according to the position of the piston and inject fuel. When the brake is released, the system directly ignites the cylinder that has been injected into the fuel, which is equivalent to igniting immediately after the brake is released. The starter is no longer required to provide initial power to the engine, and the vehicle battery only needs to provide ignition. Energy, without the need for a large current output, drives the starter.
Schematic diagram of the engine restart process
So, the problem came out. For the gasoline engine, the ignition can be carried out immediately, but for the diesel engine, it is compression-ignition. Can this method also be applied? It is impossible to stop the piston at the critical point of compression ignition. Right?
of course not. The i-stop system also precisely controls the position where the piston stops, but the diesel engine still needs a compression stroke, but the i-stop only needs one cycle to start the engine compared to the normal diesel engine's automatic start and stop requires two cycles.
According to Mazda's official data, the i-stop system restarts the gasoline engine for 0.35 seconds and the diesel engine for nearly 0.4 seconds. And it can be said that it is a seamless restart, so the process of restarting is smoother.
In order to ensure the service life and performance of the engine, the i-stop system can adjust the idle stop time for different driving conditions, and can detect the power status of the vehicle battery. When the voltage is found to be insufficient, the engine will be forced to start to charge the vehicle battery. .
In addition, the i-stop system is equipped with an electric hydraulic pump that assists the mechanical hydraulic pump when the engine is restarted. When the oil pressure returns to the working range, it stops working.
Toyota Denso: idling stop technology that can be installed later
Another Japanese car company Toyota chose the second route, the system was named idle-stop (idle stop system).
Most starters push the pinion of the front end out of engagement with the engine flywheel to start the engine. After the engine stops supplying oil, it is still in the running state until the engine is still running. If the engine is restarted at this time, the pinion of the starter will not be pushed out immediately, but it needs to wait for the engine to completely stop. Therefore, in the case where the idle time is too short, the engine restart process will be relatively slow.
In order to solve this problem, Toyota and Japan's auto parts supplier Denso have jointly developed a new type of starter - permanent mesh starter. As the name implies, the pinion of the starter is always in mesh with the flywheel of the engine, and a one-way clutch is added between the meshing gear and the engine. After starting, the clutch is disconnected and the engine runs by itself.
However, this solution also requires the addition of a clutch to the engine, which is based on a permanent-engaged starter. There are two solenoids in the TS starter, which independently control the push-out of the pinion and the operation of the starter.
That is to say, it is equivalent to adding a switch in the starter, one switch controls the push of the pinion, and the other switch controls the operation of the starter. When the engine is started for the first time, the starter pushes out the pinion and starts the starter at the same time. When the engine is driven, the switch that controls the starter is turned off, and the switch that controls the pinion is always closed; after the idle stop system starts working, The starter only needs to close the running switch to directly drive the engine without waiting for the engine to completely stop.
The TS starter does not need to be modified for the engine. It only needs to be replaced by the starter. Therefore, this technology can be retrofitted and can be enjoyed by the factory.
In addition, the department that introduces the pinion in the starter has added a spring to reduce the damage caused by the impact of the pinion and the engine end gear to increase the service life of the engine.
Compared with Mazda's i-stop, Toyota's idle stop system has advantages and disadvantages:
1. Mazda's i-stop system must be activated after the engine is completely stopped, and Toyota's idle stop system can restart the engine at any time, and with the technical blessing of Denso, the pre-installed and post-elected, and no brand limits;
2. From the implementation of the starting process, Toyota still uses the vehicle battery to supply power to the starter. The starter drives the engine in the same mode as the light automatic start and stop and semi-automatic start and stop mentioned above. Therefore, for the vehicle battery Life is still a test.
From the author's preference, the former is amazing, and the latter is amazing. Moreover, there are those siege lions with different brain circuits. In the future, there will be more wonderful and more subtle designs.
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