Made in Russia

In the bowels of the EUR

Preparation for serial production of electric power steering is nearing completion

for vazovskih cars

Alexander BUDKIN

WHY ELECTRO. Power steering on modern cars is a must. Both for the convenience and comfort of the driver, and for safety. But which of the amplifiers to prefer - hydraulic or electric? Oddly enough, until recently, engineers did not have much debate on this subject. It turned out to be easier to use the liquid in due time and, without having to wait, the hydraulic booster took a strong position in the car. But time passed, the views on the design of cars changed, and the old GUR ceased to suit many. It does not provide as flexible control as the engineers would like today, it does not always leave the driver normal feedback, and sometimes asks for service. In addition, his pump runs continuously, taking 5-7% of engine power. In general, the prospect loomed before GUR to go on a well-deserved rest. And since a holy place does not happen empty, the electric power steering manifested itself - the EUR.

An additional impetus for the development of electric amplifiers was given by the on-board electronics of the car. After all, such devices can be flexibly controlled, changing the gain depending on any factors, up to the crosswind speed, if it is known. Controlling the current is simpler than the performance of a pump mechanically coupled to the motor. But in order to take full advantage of the EUR, you have to conjure him.

“AVIAAGREGAT” - “NIVE”. It is gratifying that the technical fashion this time did not go around our country. A few years ago, the Makhachkala Aviaagregat plant, the Novocherkassk NPP Emetron and, in fact, AvtoVAZ took over the joint development of the EUR for the new Viva 2123 Niva (see also ZR, 2000, No. 2). The task of the first is to work out the design and prepare serial production, the second is to create the brain of an electric amplifier and calculate a super-unusual electric motor, and the third - of the customer - to give the first two tasks and evaluate what they get by periodically conducting tests. Today, three years later, we can already say: the electric amplifier for the new Niva is ready. The layout options for installing the EUR to the "top ten" and "Kalina" are being worked out, but this is a prospect - about it later. And now let's look into the bowels of an unusual device for us.

"KNOW-HOW." For compatibility with any type of steering gear, the EUR needs to be mounted in the steering column, which means it should fit inside the cabin. This limits its size, permissible noise level and electromagnetic interference. It must also be ensured that any theoretically possible short circuits or breakdowns are not detrimental. In other words, the device is inconceivable without constant self-diagnosis. Finally, there are two more requirements, the most stringent ones: good feedback (driver’s sense of road) and an impressive 35 N.m moment, which should be produced by an all-terrain vehicle amplifier.

Based on all this, the designers came to the decision: the electric motor of the EUR should be brushless. Otherwise, high torque (and, therefore, high current) will require a massive brush assembly with significant internal friction, and the driver will think that the invisible hand constantly holds the steering wheel, preventing it from turning and returning to “zero”. In addition, traditional windings on the rotor of an electric motor with a large current and small dimensions will inevitably lead to its overheating.

Unfortunately, the most common brushless motor - a valve motor with several permanent magnets on the rotor - is not suitable here. The selection of powerful magnets that can provide an uneven moment within 2% (such are the requirements of VAZ) is a difficult task in mass production. I had to dwell on a jet-induction engine - an ultramodern, but at the same time super complicated. In fact, it is a stepper motor: without a smart control unit, it can only rotate the rotor a small angle, and then … the computer must analyze the position of the rotor, change the “phase” in the stator windings and make the motor rotate one more step. Here, as you know, ensuring uniformity is even more difficult. True, this complexity is no longer technological, but design: complex phase rotation, cunning rotor geometry (clearly visible close), and a difficult control program. Engineers from Novocherkassk were able to cope with this today - they began work in this area one of the first, not only in the country, in the world.

The unusual know-how electric motor, which found a place in a small unit, is not limited to. Another achievement used in the EUR is an already technological one - a polished three-way involute worm. Only he, possessing a large gear ratio (18.3) and small dimensions, can provide an inherent resource of 180 thousand km and minimal friction losses in the worm pair. There was no technological equipment capable of processing such a worm in the country. Engineers of the Makhachkala Aviation Unit have adapted … a turning and backing machine for this, they say, not for the first time.

Now about the brain of an electric booster. It works not only to alternate phases on the motor windings in time. The built-in self-diagnosis system constantly monitors the condition of the unit, analyzing the signals of the sensors and monitoring the temperature of the electric motor. Feels that the device is malfunctioning - disconnects. When connected to the diagnostic tools at the workshop, the amplifier computer will be able to issue one of 32 (!) Trouble codes. In the standard mode of operation, the EUR control system asks the car for speed, engine speed and the signal from the ignition switch. It independently determines the force on the steering wheel and its position. Summing up the accumulated information, a smart electric power amplifier helps the driver to turn the steering wheel, accurately dosing the degree of its intervention.

FOR GOOD DAMAGE. To start mass production, of course, you need start-up capital. With great difficulty, the plant managed to accumulate it through the sale of other automotive products - pumps and jacks, which go to complete the VAZ cars. The proceeds from the first stage of production development will be enough. And then … the plant won a tender by the Russian government for investment in economically advantageous projects. Allocated 25 million rubles. it would be enough to create five thousand jobs in the first three years and bring about 300 million rubles to the budgets of all levels. But money did not reach the plant, as it happens today in Russia. Apparently, one of the officials decided to use the funds "for the good" of his native land, thereby ruthlessly robbing him. The plant, of course, will find a way out, but time, time …