Steering. Device, species and principle of the steering mechanism Adjusting the worm steering mechanism

The steering mechanism is the basis of the steering where it performs the following functions:

• an increase in the effort attached to the steering wheel;
• transmission of force steering;
• spontaneous refund of the steering wheel into a neutral position when removing the load.

In essence, the steering mechanism is a mechanical transmission (gearbox), therefore its main parameter is the gear ratio. Depending on the type of mechanical transmission, the following types of steering mechanisms are distinguished: wheels, worm, helical.

Rack steering mechanism

The robes steering mechanism is the most common type of mechanism installed on passenger cars. The roll steering mechanism includes a gear and steering rack. The gear is installed on the steering wheel shaft and is in constant engagement with the steering (toothed) rail.

The operation of the rush steering mechanism is as follows. When the rack steering wheel is rotated to the right or left. When the rail movement moves the steering drive attached to it and rotate controlled wheels.

The robes steering mechanism distinguishes simplicity of design, respectively, high efficiency, as well as high rigidity. At the same time, this type of steering mechanism is sensitive to shock loads from road irregularities, prone to vibrations. By virtue of their constructive features, the roll steering mechanism is established on front-wheel drive vehicles with independent suspension controlled wheels.

Worm steering mechanism

The worm wheel mechanism consists of a global worm (worm with a variable diameter) connected to the steering shaft, and the roller. On the shaft of the roller outside the power of the steering mechanism, the lever is installed (tha) associated with the steering rods.

The rotation of the steering wheel ensures rolling through the worm roller, the swing swing and move the steering drive than the rotation of the controlled wheels is achieved.

The worm steering mechanism has less sensitivity to shock loads, provides large angles of rotation of controlled wheels and, accordingly, the best maneuverability of the car. On the other hand, the worm mechanism is complicated in the manufacture, so roads. Steering with such a mechanism has a large number of connections, so requires periodic adjustment.

Worm steering mechanism applied on passenger cars of high passability with dependent suspension controlled wheels, light trucks and buses. Previously, this type of steering mechanism was established on the domestic "classic".

Screw steering mechanism

The screw steering mechanism combines the following structural elements: screw on the steering wheel shaft; nut moving along the screw; Shooty rail, sliced \u200b\u200bon a nut; toothed sector connected to the rail; Steering tush, located on the shaft of the sector.

A feature of the screw steering mechanism is the connection of the screw and nut with the help of balls, which is achieved by smaller friction and pair wear.

The principal operation of the screw steering mechanism is similar to the work of the worm mechanism. The rotation of the steering wheel is accompanied by the rotation of the screw, which moves the nut on it. In this case, the circulation of balls occurs. Nut through a toothed rail moves the toothed sector and with it the steering tower.

The helical steering mechanism in comparison with the worm mechanism has a larger efficiency and implements great efforts. This type of steering mechanism is set on separate passenger cars of executive class, heavy trucks and buses.

The steering wheel includes a steering wheel, the shaft, enclosed in the steering column, and the steering gearbox associated with the steering wheel drive. The steering mechanism allows to reduce the effort applied by the driver to the steering wheel to overcome the resistance arising from rotating the driven wheels of the machine due to friction between tires and expensive, as well as ground deformations when moving along ground roads.

The steering gearbox is a mechanical transmission (for example, a toothed) installed in the housing (crankcase) and having a gear ratio of 15 - 30. The steering mechanism reduces the force applied by the driver to the steering wheel associated with the shaft with the gearbox, so many times. The greater the gear ratio of the steering gear, the easier it is to rotate the driven wheels to the driver. However, with an increase in the gear ratio of the steering gearbox for rotation to some angle of the controlled wheel associated with the drive parts with the output shaft of the gearbox, the driver must turn the steering wheel to the larger angle than at a small gear ratio. When TS moves at high speed, it is harder to make a sharp turn at a large angle, since the driver does not have time to turn the steering wheel.

Transmission ratio of the steering gear:

Up \u003d (AP / AC) \u003d (PC / PP)
where the AR and AC - the angles of rotation of the steering wheel and the output shaft of the gearbox; RR, RS - an effort attached to the driver to the steering wheel, and the effort on the outlet of the steering mechanism (compound).

So, for the rotation of the bump 25 ° with the transfer of the steering gearbox, equal to 30, the steering wheel must be rotated by 750 °, and at Up \u003d 15 - at 375 °. With an effort on a steering wheel 200 H and with a gear ratio Up \u003d 30, the driver on the output link of the gearbox creates a force of 6 kN, and at Up \u003d 15 - 2 times less. It is advisable to have a variable gear ratio of the steering mechanism.

With small angles of rotation of the steering wheel (no more than 120 °), preferably a large gear ratio, providing easy and accurately controlled by car when driving at high speed. At low speeds, a small gear ratio allows for small angles of rotation of the steering wheel to obtain significant angles of rotation of controlled wheels, which ensures high maneuverability of the car.

Choosing the transfer ratio of the steering mechanism, proceed from the fact that the controlled wheels should be rotated from the neutral position to the maximum angle (35 ... 45 °) not more than 2.5 turnover of the steering wheel.

Steering mechanisms can be several types. The most common of them are the "worm-three-graby roller", "worm-gear" and "screw-ball-rack-rack-gear". The gear in the steering mechanism is made in the form of sectors.

The steering mechanism converts the rotational movement of the steering wheel into the angular movement of the steering tower mounted on the output shaft of the steering gearbox. The steering mechanism when moving the fully loaded car, as a rule, should ensure an effort on the rim of the steering wheel not more than 150 N.

The angle of free rotation of the steering wheel (backlog) for trucks should usually not exceed 25 ° (which corresponds to the length of the shower 120 mm, measured by the rod of the steering wheel) when the cargo car moves in a straight line. For cars of other types of backlash, the steering wheel is different. The backlash arises due to wear in the operation of the steering parts and the tag of the steering mechanism and the drive. To reduce friction losses and protect the parts of the steering gear from corrosion into its crankcase, fired on the car frame, poured special transmission oil.

When operating the vehicle, it is necessary to adjust the steering mechanism. Adjustable steering devices are designed to eliminate, firstly, the axial backlash of the steering shaft or the drive element of the gearbox, and secondly - the backlash between the leading and slave elements.

Consider the design of the steering mechanism of the type "global worm-three-gravy roller".

Fig. Steering mechanism of the type "Global Worm-three-grade roller":
1 - steering gearbox; 2 - shaft head of the steering tower; 3 - three-grade roller; 4 - adjusting gaskets; 5 - worm; 6 - steering shaft; 7 - axis; 8 - Bearing of the shaft shaft; 9 - lock washer; 10 - cap nut; 11 - adjusting screw; 12 - shaft of the bump; 13 - seal; 14 - steering bumps; 15 - Nut; 16 - Bronze bushing; h - adjustable roller engagement depth with worm

A global worm 5 is installed in a steering gear crankcase 1 on two conical roller bearings that are well perceived axial efforts that occur when the worm interacts with a three-grade roller 3. The worm pressed on the slots available at the end of the steering shaft 6 provides with a limited length of a good gearing rollers with a limited length. With cutting worm. Due to the fact that the operation of the load is dispersed in several ridges as a result of their contact with the worm, as well as replacing the sliding friction in the engagement of significantly smaller rolling friction, a high wear resistance of the mechanism and a fairly large efficiency is achieved.

The axis of the roller is fixed in the head 2 of the shaft 12 of the steering bump 14, and the roller itself is installed on needle bearings that reduce the loss when scrolling the roller relative to the axis 7. The roller tower shaft supports are, on the one hand, the roller bearing, and on the other - bronze bush 76. The sump is connected to the shaft with the help of small slots and is fastened with a washer and nut 15. To seal the shaft of the tower, an oil carrier is used.

The engagement of the worm with the ridges is carried out in such a way that with a position corresponding to the straight-line movement of the machine, the free course of the steering wheel is practically absent, and as an angle of rotation of the steering wheel increases, it increases.

Adjusting the tightening of the steering shaft bearings is carried out by changing the number of gaskets installed under the cover of the crankcase, its plane be resting in the end of the extreme conical roller bearing. Adjusting the engagement Worm with a roller is carried out by offsetting the shaft of the steering tower in the axial direction using the adjusting screw 11. This screw is installed in the side cover of the crankcase, the outside closed with a cap nut 10 and is fixed with a locking washer 9.

On heavy loading vehicles, steering mechanisms of type "Worm-side sector (gear)" or "screw-ball-rack-rack gear", having a large area of \u200b\u200bcontact of the elements and, as a result, small pressures between the surfaces of the gearbox pairs are used.

Steering mechanism of the "worm-side sector" type, the simplest according to the design, is used on some cars. In engagement with Worm 2 enters the side sector 3 in the form of a part of the gear with spiral teeth. The lateral sector is made as a single whole with a shaft of 1 bump. The sump is located on the shaft installed on needle bearings.

The gap in the engagement between the worm and the sector is inconsistent. The smallest gap corresponds to the average steering wheel. The gap in the engagement is regulated by changing the thickness of the washer located between the side surface of the sector and the cover of the steering gearbox.

The design of the steering mechanism of the type "Screw-ball nut-rail-sector" is shown in the picture. The steering wheel shaft by means of the cardan transmission is connected to the screw 4 interacting with the ball nut 5, fixed by the locking screw 15 in the piston rail 3. The thread of the screw and the nuts are made in the form of semicircular grooves filled with balls 7, circulating threads when rotating the screw. The extreme nuts of the nuts are connected by a gutter 6 with an outer tube that provides the circulation of balls. The friction of rolling these thies on the thread during the rotation of the screw is insignificant, which causes the high efficiency of such a mechanism.

Fig. Steering mechanism like "Worm-side Sector":
1 - Tree shaft; 2 - worm; 3 - lateral sector

Fig. Rule mechanism of the type "Screw-ball nut-rail-sector":
1 - cylinder cover; 2 - Carter; 3 - Rake piston; 4 - screw; 5 - Ball nut; 6 - chute; 7 - balls; 8 - intermediate cover; 9 - spool; 10 - control valve housing; 11 - Nut; 12 - upper cover; 13 - Spring Plunger; 14 - plunger; 15 - locking screw; 16 - gear sector (gear); 17 - shaft; 18 - Cup; 19 - side cover; 20 - stop ring; 21 - adjusting screw; 22 - ball finger

When the car is rotated, the driver with a steering wheel and shaft rotates the screw, relative to the axis of which the ball nut moves on the circulating balls. Together with the nut, the piston-rail moves, turning the toothed sector (gear) 16, made as a single whole with a shaft 17. The tower 18 is mounted on the shaft using the slots, and the shaft itself is placed on the bronze bushings in the 2 steering gear crankcase.

Steering

The steering control is called a set of devices that rotate the driven wheels of the car.

Fig. 2. Steering controls with independent (A) and dependent (b) controlled pendants:
1 - steering wheel; 2 - shaft; 3 - steering (mechanism); 4 and 12-pin;
5, 9, 11 and 14 - levers; 7 - Cup; 6, 8, 10, 13 and 15 - traction

Traumatic steering

In addition to the steering wheel with a recessed hub and two spokes, which significantly reduces the severity of the injured injuries when they hit, a special energy absorbing device is installed in the steering mechanism, and the steering shaft is made compound. All this ensures a slight movement of the steering shaft inside the car body with a frontal collision with an obstacle.

a - the folding steering shaft; b - bellows; in - perforated shaft; 1- bracket; 2 - cardan hinge; 3 - cylinder; 4- trumpet

In the trauma-safe steering controls of passenger cars, other energy absorbing devices are used, which connect the composite steering shafts: rubber couplings of a special design, a device such as a Japanese lantern, in the form of several longitudinal plates welded to the ends of the connected steering parts. In collisions, the rubber coupling is destroyed, and the connecting plates are deformed, reducing the movement of the steering shaft inside the body's cabin.

Steering gear

The steering is called the mechanism that converts the rotation of the steering wheel to the translational movement of the steering drive, which causes the rotation of the controlled wheels. It serves to increase the driver's effort attached to the steering wheel, and transfer it to the steering drive.

An increase in the force attached to the steering wheel is occurring due to the gear ratio of the steering mechanism. The transfer number of the steering mechanism is the ratio of the rotation of the steering wheel to the corner of the shaft of the steering tower. Depending on the type of car, it is 15 ... 20 in passenger cars and 20 ... 25 in trucks and buses. Such gear ratios for 1 ... 2 full turnover of the steering wheel provide rotate controlled wheels for maximum angles (35 ... 45 °).

Various types of steering mechanisms are used on cars.

a - worm-roller; b - vinatoroeh; in - wheels; 1 - worm; 2, 4 and 9 - shafts; 3 - roller; 5 - screw; 6 - nut; 7 - ball; 8 - sector; 10 - gear; 11 - Reika

Steering wheel drive

The steering wheel drive is called a system of thrust and levers that communicates the controlled wheels of the car with a steering mechanism. It serves to transmit effort from the steering mechanism to controlled wheels and ensure their correct turn.

On vehicles use different types of steering wheel drives.

The main part of the steering drive is steering trapezium

The steering trapezium can be anterior or rear depending on its location in front of the axis of the front controlled wheels (see Fig. 2, a) or for it (see Fig. 2, b). The use of a steering wheel with anterior or rear steering trapezium depends on the layout of the car and its steering. At the same time, the steering wheel can be with a continuous or incisional steering trapezium depending on the type of suspension.
The continuous steering trapezium has a solid transverse steering, connecting controlled wheels (see Fig. 2, b).
Such a trapezium is used with the dependent suspension of the front controlled wheels on trucks and buses.
A split steering trapezium has multiple transverse steering, connecting controlled wheels (see Fig. 2, a).
It is used with independent suspension of controlled wheels on passenger cars.

Steering amplifier

The steering amplifier is called a mechanism that creates under the pressure of liquid or compressed air an additional force on the steering wheel, which is necessary to rotate the driven wheels of the car.

1 - spool; 2, 3 and 11- oil carriers; 4- springs; 5-wheel; 6 and 9 - traction; 7 and 8- levers; 10 - piston; but...g. - cameras; A and B - cavity; B - tank; GG - HydroNesos; PM - steering mechanism; Gr - hydraulic distributor; Hz - hydraulic cylinder

Steering designs

Left, trauma-safe, without amplifier. The safety of the steering is provided by the design of the intermediate shaft of the steering wheel and the special fastening of the steering shaft to the car body.

1 and 3 - traction; 2 - Cup; 4 and 7 - levers; 5 - coupling; 6 - fist; 8 and 16 - brackets; 9 - Bearing; 10 - pipe; 11 and 13 - shafts; 12 - Carter; 14 - column; 15- steering track; 17 finger; 18 - case; 19 - tip; 20 - insert; 21 - Spring; 22 - plug

The steering mechanism of the passenger car VAZ of high patency:
1 - Cup; 2 and 13 - cuffs; 3- sleeve; 4 - Carter; 5 and 12 shafts; 6 - roller; 7-screw; 8-nut; 9- traffic; 10 and 16-covers; 11 - worm; 14 and 18 - bearings; 15- adjusting gaskets; 17-axis

1 - lever; 2 - hinge; 3 and 5 - thrust; 4th 34 - nuts; 6 finger; 7 and 13- covers; 8 - insert; 9 and 33 - springs; 10 and 20 - bolts; 11- bracket; 12 - support; 14 and 15 - plates; 16 and 17 - sleeves; 18-rail; 19- Carter; 21 - coupling; 22-quenching device, 23 - steering wheel; 24, 29 and 31 - bearings; 25 - shaft; 26-column; 27- bracket; 28 - Cap; 30- gear; 32- Emphasis

In the process of movement, the driver is experiencing a constant need for car control and expensive. Very often there is a need to change the mode of movement: check-in to parking or departure from it, changes in the direction of following (turn, reversal, rebuilding, advance, overtaking, levers from, movement by reverse, etc.), stopping or parking. The implementation of these actions ensures the steering of the car, which is one of the most important systems of any vehicle.

General device and principle of work

The total steering device, despite the large number of nodes and aggregates, is pretty simple and effective. The logistics and optimality of the design and functioning of the system is proved by at least the fact that the steering has not undergone global entrepreneurial changes for the long-term theory and the practice of automotive industry. Initially, it includes three main subsystems:

1. steering column designed to transmit rotational steering movement;
2. the steering mechanism is a device that converts rotational steering movements into progressive movement of the drive parts;
3. a steering wheel drive, which is able to bring control functions to rotary wheels.

In addition to the main subsystems, large-tonny trucks, route vehicles and many modern cars have a special power steering device, allowing the use of the generated effect facilitating its movement.

Thus, the steering circuit is quite simple and functional. The steering wheel, as the primary knot, well acquainted with each driver, under the influence of his thought and the effects of force makes rotational movements in the necessary direction. These movements through the steering shaft are transmitted to a special steering mechanism, where the torque conversion is performed into plane movements. The latter via the drive report the necessary angles of turnover by control wheels. In turn, pneumatic, hydraulic, electrical and other amplifiers (if available) facilitate the rotation of the steering wheel, making the process of controlling the vehicle more comfortable.
This is the basic principle for which the car steering works.

Steering column

The steering scheme necessarily includes a column that consists of the following parts and nodes:

• steering wheel (or steering wheel);
• shaft (or shafts) columns;
• casing (pipes) columns with bearings intended for rotation of the shaft (shafts);
• fastening elements to ensure fixedness and stability of the structure.

The scheme of the column is to apply a driver's effort on the steering wheel and the subsequent transmission of directionally rotational movements of the steering wheel with the entire system, if the driver wants to change the movement mode of the car.

Steering gear

The steering mechanism of any car is a way to transform the rotation of the column in the transit movements of the steering drive. In other words, the mechanism functions are reduced to ensure that the steering turns turn into the desired movement of the thrust and, in course, the scores, wheels.


The steering device is variable. Currently, it is represented by two basic principles - worm and rack, which differ in the methods of transforming torque.
The total worm-type steering device includes:

1. a couple of details of the "worm-roller";
2. carter of the specified pair;
3. steering tower.

Power steering

The steering of modern cars is equipped with a special additional option - amplifier. The steering amplifier is a subsystem consisting of a mechanism that allows you to significantly reduce the driver's effort when the steering wheel is rotated and driving.


The main types of steering amplifiers are:

1. pneumatic receivers (using compressed air);
2. hydraulic liner (based on changing the pressure of special fluid);
3. electric powerful (operating on the basis of an electric motor);
4. electrohydroSiller (applying a combined principle of operation);
5. mechanical amplifier (special mechanism having an enlarged gear ratio).

Initially, the amplification system was used on large-capacity and large-sized techniques. Here, the driver's muscle strength was clearly not enough to accomplish the conceived maneuver. In modern passenger cars, it is used as a means of ensuring comfort while driving.

Basics of operating management system

During the operation of the car, individual nodes and aggregates included in the steering system are gradually come into disrepair. Especially, it is aggravated in conditions of motion on poor-quality roads. Insufficient attention of the driver, licenses devoted to the prevention of faults, as well as the low quality of spare parts and components, contributes to the wear of the system. The low qualification of the servicemen who trusts the maintenance of his car is also plays far from the latter role.

The importance of the car management system is due to the requirements of the overall road safety. So, the norms of "basic provisions for the admission of vehicles to operation ..." and paragraph 2.3.1 of the traffic control panel categorically prohibit movement (even before the car service or parking space) on the vehicle in the presence of faults in the steering system. These faults include:

• excess of the permissible free stroke (backlash) of the steering wheel (10 degrees for passenger cars, 25 - for freight, 20 - for buses);
• move the details and nodes of the control system not provided by the manufacturer;
• availability of non-intricate in threaded compounds;
• inadequate functioning of the steering amplifier.

However, this list of faults is not exhaustive. In addition to them, there are other "popular" flaws of the system:

1. tight rotation or steering;
2. knock or beating that go into the steering wheel;
3. leakage of the system, etc.

Such malfunctions are considered permissible during the operation of the vehicle, if the shortcomings of the system have not been evaluated.

Summarize. The steering is one of the most important components of the design of the modern vehicle. It requires constant monitoring of its condition and the implementation of timely and high-quality service and maintenance.

It provides a rotation of controlled wheels with a small force on the steering wheel. This can be achieved by increasing the gear ratio of the steering mechanism. However, the gear ratio is limited by the number of revolutions of the steering wheel. If you select a gear ratio with the number of steering wheel speeds, more than 2-3, then the time required to turn the car is significantly incremented, and this is unacceptable by the conditions of movement. Therefore, the gear ratio in the steering mechanisms is limited in the range of 20-30, and to reduce the effort on the steering wheel in the steering mechanism or the drive embedding the amplifier.

The limitation of the gear ratio of the steering mechanism is also associated with the property of reversibility, i.e. the ability to transmit opposite rotation through the mechanism on the steering wheel. At high gear ratios, friction in the engagement of the mechanism increases, the properties of the reversibility disappears and the self-return of controlled wheels after rotation into the straight position is impossible.

Steering mechanisms depending on the type of steering gear are divided into:

worm

screw

gear.

The steering mechanism with the transmission of the Worm type - the roller has a worm as a leading link, fixed on the steering shaft, and the roller is mounted on the roller bearing on the same shaft with a compartment. To make a complete engagement with a large corner of the worm turn, the worm cutting on the circumference arc - the globade. Such a worm is called global.

In the screw mechanism, the rotation screw associated with the steering shaft is transmitted to the nut, which ends with a railway with the toothed sector, and the sector is installed on the same shaft with a compartment. Such a steering mechanism is formed by the steering transfer of the type of screw-nut-sector.

In the gear steering mechanisms, the steering transmission is formed by cylindrical or conical gears, they also include the transmission of the type of the Rake gear. In the latter, the cylindrical gear is associated with the steering shaft, and the rake, engaged with the gear teeth, acts as a transverse thrust. Worm-roller transmissions and transmission types are preferably used on passenger cars, as they provide a relatively small gear ratio. For trucks, steering gears type worm-sector and screw-nut-sector, equipped either built into the mechanism of amplifiers, or amplifiers deposited in the steering wheel drive.

3.2.Read drive.

The structures of the steering drive differ in the arrangement of the levers and the thrust of the steering trapezium in relation to the front axle. If the steering trapezium is ahead of the front axle, this design of the steering drive is called the front steering trapezium, at the rear arrangement - the back trapezium. The design of the front wheels suspension is a large influence on the design and steam of steering trapez.

With a dependent suspension (Fig. 2. (a)), the steering wheel has a simpler design, as it consists of a minimum of parts. The transverse steering traction in this case is made whole, and the tshaka swings in the plane parallel to the longitudinal axis of the car. You can make a drive and with a compass swallowing in a plane parallel to the front bridge. Then the longitudinal thrust will be absent, and the effort from the tower is transmitted directly into two transverse thrust associated with wheel pin.

With an independent front wheel suspension (Fig. 2. (b)), the steering diagram is constructively more complicated. In this case, additional drive details appear, which are not in the diagram with a dependent suspension wheels. The design of the transverse steering thrust changes. It is made of dismembered, consisting of three parts: the main transverse thrust and two side traction - left and right. For support, the main traction serves a pendulum lever, which in shape and sizes corresponds to the compliance. The connection of the side transverse tap with rotary levers of the TPEF and with the main transverse burden is made using hinges that allow independent movement of the wheels in the vertical plane. The considered steering actuator is used mainly on passenger cars.

The steering wheel drive, being part of the car steering, ensures not only the possibility of rotation of the controlled wheels, but also allows wheels to be fluctuated when they are driving on the road irregularities. In this case, the drive parts are obtained by relative movements in vertical and horizontal planes and the turns rotating wheels are transmitted on the turn. Compound of parts with any drive diagram is made using ball joints or cylindrical.