Subaru Legacy/Outback

1999-2003 of release

Repair and operation of the car

Steering

Design and the principle of functioning of elements of the hydrostrengthened steering drive - the general information

The rotor operating valve

Design of the rotor managing director of the valve

The operating valve consists of the rotor rotating together with a steering in bulk, the leading gear wheel entered into gearing with a rotor by means of the torsion core and rotating together with a coupling gear wheel. The design of the valve is presented on an illustration.

The flutes of C and D forming channels through passage from V1 on V4 for a stream of hydraulic liquid are provided in a rotor and the coupling of valvate assembly.

The configuration of a gap of gearing of a gear wheel with a rotor provides possibility of the manual drive of a lath in case of refusal of system of hydrostrengthening.

When the torsion core is twisted under the influence of the torque enclosed to a steering wheel, the provision of a rotor concerning the coupling changes that is followed by change of the section through passage of V1 ÷ V4 channels. This mechanism allows to correlate a pressure of a working body of system to the size of the effort enclosed to a steering wheel.

When the steering wheel is released a rotor and the coupling keep in neutral situation, in the carburetor the V1, V2 and V3 channels formed by flutes of C and D keep identical sections through passage. Thus the stream of the liquid forced by the pump will be redirected back in the GUR tank, and the steering rack remains in a free state.

Turning of a steering wheel leads to the right to a priotkryvaniye of V1 and V3 channels while V2 and V4 channels are almost completely blocked. Thus pressure in the camera A of the power cylinder increases in proportion to decrease in a consumption of hydraulic liquid via V2 and V4 channels, on the other hand, pressure in the camera B decreases due to removal of liquid in the GUR tank on the V3 channel. the arising difference of pressure from the different parties of the piston leads to shift of a lath in the demanded direction (to the right). At rotation of a steering wheel to the left the picture changes specularly that leads to shift of a steering rack in the demanded direction.

Violation of serviceability of functioning of system of hydrostrengthening (for example, as a result of break of a driving belt) leads to refusal of increase of hydraulic pressure therefore the torque enclosed to a steering wheel starts being transferred mechanically from a rotor of the managing director of the valve directly to the leading gear wheel of the steering mechanism.

Design and principle of functioning of the steering pump

The drive of the shiberny steering pump is carried out from the engine by means of a wedge-shaped belt.

The tank of hydraulic liquid is installed on a body element of the car.

L models 2.0 and 2.5

The scheme of connection of the pump GUR to the steering mechanism is shown on an illustration.

The structure of the pump switched on three valves: valve of management of a liquid consumption and also sensitive to change of pressure and reducing valves.

The valve of management of a consumption of working liquid provides maintenance of a consumption of hydraulic liquid at the identical level regardless of engine turns.

The valve, sensitive to change of pressure, provides return of liquid to the GUR tank at the released steering wheel.

The reducing valve serves for protection of system against excessive increase of pressure, a cut could result, for example, from turning of a steering wheel at all length of the course of its rotation.

The basis of pump assembly is made placed in an eccentric ring by the rotor equipped with ten sliding blades (shiber). At rotation of a rotor freely put shiberny shovels under the influence of centrifugal force seek to move forward from the directing grooves in the radial direction, nestling thus on walls of the eccentric chamber having an oval form. The liquid which is soaked up through inlet ports in space between shovels in process of reduction of volume of a cavity compresses and under a pressure is pushed out through final ports to the working highway of system of hydrostrengthening.

The valve of management of a consumption of liquid consists of the cylindrical zolotnik which is wrung out to the right in process of increase of pressure of working liquid owing to increase in turns of the engine, - such push-up of a zolotnik is followed by narrowing of the section through passage of a throttle opening and, as a result, to reduction of a consumption of liquid.

The left end of pressure of the valve, sensitive to change, it is open towards release of the pump, and right it is connected to an exit of the valve of management of an expense.

At the released steering wheel the working liquid passed via the valve of management of an expense towards the power cylinder of the steering mechanism will be redirected in the GUR tank bypassing the rotor managing director of the valve that does not allow to raise to pressure on the right side of valvate assembly. Excess of pressure forced by the pump on the left side of the valve concerning pressure leads to shift of a zolotnik of the valve to the right and, as a result, to opening of the drain port locked by a zolotnik and the redirection to the liquid forced by the pump in the GUR tank and to the corresponding pressure decrease in pump assembly on the right.

Rotation of a steering wheel in any direction leads to increase in pressure of the management of an expense missed via the valve to the piston of a steering rack of a stream of liquid. Thus the zolotnik of the valve pressure, sensitive to change, continues to be kept by the pressure of the liquid forced by the pump which is wrung out to the right for some time. At some point, when pressure on the left side of valvate assembly reaches critical value, the zolotnik is wrung out to the left, blocking drain port. As a result pressure in pump assembly increases that provides adequate increase of a pressure in a working chamber of the steering mechanism.

Basic element of the reducing valve is the control ball which is propped up by a spring. From the party opposite to a spring on a ball pressure developed by the expense passed via the valve of management and the liquid stream given to the steering mechanism makes impact. Excessive increase of hydraulic pressure leads to compression of a spring and push-up of a ball to the left therefore the drain channel created in a body of valvate assembly is slightly opened and excess of liquid is dumped in the GUR tank.

Models of 3.0 l

The scheme of functioning of the steering pump on models 3. 0 l it is shown on an illustration.

The consumption of hydraulic liquid in system of hydrostrengthening of a wheel of models of 3.0 l is regulated according to change of turns of the engine that guarantees the adequate resistance of a steering wheel to rotation at high speeds of the movement.

The basis of a design of pump assembly is made by the shiberny pump of variable productivity providing decrease in quantity of the system which is pushed out to the working highway for one turn of a rotor of hydraulic liquid at increase in turns of the engine. Pump assembly switched also on the managing director and reducing valves.

The design of the shiberny pump is presented on an illustration. The main distinctive feature of this design is mobile installation of an eccentric ring which can be displaced concerning a rotor. Such decision allows to carry out adjustment of productivity of the pump on one turn of a rotor.

The principle of functioning of the steering pump of variable productivity at small turns of the engine (sector In a curve on an illustration)

Owing to design features, the liquid forced by the pump moves on the operating valve along with two parties. Thus on the left side of valvate assembly liquid moves from unregulated final port of the pump while before giving on the right side of the valve it is passed previously through a throttle opening, providing a certain decrease in a pressure. Thus, pressure on the left side of the operating valve is always a little higher, than from the right.

During the work on low turns the pump is provided by a low pressure and the resulting difference of pressure from the different parties of the valve is small. Thus the valve under the influence of the effort developed by the spring remains wrung out to the left, and the liquid which is under atmospheric pressure from the GUR tank comes to the camera A of an external cavity of pump assembly. On the other hand, In liquid is in a chamber under pressure determined by resistance of a throttle opening of adjustable final port. As a result, the eccentric ring which is in addition drawn in on the right by a spring remains wrung out to the left and eccentricity of a rotor chamber (and, therefore, and pump productivity) is supported maximum.

The principle of functioning of the steering pump of variable productivity at averages and high turns of the engine (curve V-D sector on an illustration)

At averages and high turns of the engine productivity of the pump increases. Increase of pressure before a throttle opening brings to push-up of the managing director of the valve to the right and supply of liquid from unregulated final port of the pump into the camera A after a preliminary drosselirovaniye in the left inlet port of valvate assembly. The camera B at removal of the managing director of the valve connects to the GUR tank to the right. As a result of adjustable increase of pressure in the camera A push-up of an eccentric ring to the right at the demanded size with overcoming of the counteraction developed by a spring is provided. Shift of a ring leads to decrease in eccentricity to a rotor chamber and the corresponding reduction of productivity of the pump.

The principle of operation of the reducing valve of the steering pump at sharp increases of working pressure in system of GUR

When as a result of a reversing of a steering wheel the hydraulic contour of the steering mechanism is blocked, pressure in it can increase very much considerably. On reaching working pressure in system of a certain value there is a push-up of a control ball of the reducing valve which is built in directly in a zolotnik of the operating valve. As a result of opening of the channel connecting a rotor chamber to the GUR tank dumping of excessive pressure and maintenance of the pressure head characteristic of the pump at the set level is provided.

The steering mechanism with the variable transfer relation (VGR)