RU1813348C - Agricultural machine hydraulic system - Google Patents

Abstract

Usage: agricultural engineering, hydraulic systems of mobile machines, for example, agricultural, construction and road and forestry, which provide for the adjustment of the speed of operation of the working bodies with stabilization under variable loads. The purpose of the invention is the expansion of operational capabilities to increase the productivity and reliability of the hydraulic system. The hydraulic system includes a discharge line 1 with a main metering throttle 7 connected through a main spool distributor 2 to an actuating hydraulic motor 3, and a pump discharge device having a control line 16 connected to the drain through a shut-off valve 17 and connected to the discharge line 1 after the main metering throttle 7. In this case, the hydraulic system is equipped with an additional spool valve 4 to two lines 5, 6, the first of which coincides with the discharge line 1 in the section to the main distributor 2, with an additional metering choke 8 installed in the second line 6, and two check valves installed in the mentioned lines x 5, 6, while the main metering choke 7 is installed in the spool of the additional distributor 4, and the second line 6 is connected to the first line 5 after the non-return valve 9. 1 ill. ate with

Description

The invention relates to agricultural machinery, in particular to hydraulic systems for controlling the working bodies of technological equipment, for example, an agricultural combine with stabilization of the set speed mode, regardless of the load. The invention may find application in road construction and forestry machines,

The purpose of the invention is to expand the functionality of the hydraulic system.

An additional goal is to achieve the aforementioned goal with a high degree of unification with existing hydraulic equipment. As a result, prerequisites are emerging for lowering the cost of the hydraulic system and increasing its reliability.

This goal is achieved in that the hydraulic system is equipped with an additional spool valve in two lines, the first of which coincides with the discharge in the section to the main valve, with an additional metering throttle installed in the second

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the line, and two check valves installed in said lines, the main metering choke installed in the spool of the auxiliary valve and the second line connected to the first line after the check valve.

With this design, for the stepwise change of the speed mode of operation of the actuating hydraulic motor, practically the same hydraulic apparatus (additional distributor) is used as for performing the main function of distributing the flow of the pumped working fluid. With this expansion of functionality, a high degree of unification of the hydraulic equipment used in the hydraulic system is achieved.

The proposed hydraulic system is shown in the proposed drawing.

It includes a discharge line 1 connected through a distributor 2 with a closed center to the hydraulic actuator 3. In front of the main distributor 2, an additional spool distributor 4 is installed on two lines 5 and 6. In this case, the first line 5 in the area up to the main distributor 2 coincides with the discharge line 1 The hydraulic system has a main metering choke 7 installed in the spool of the additional distributor 4 in the discharge line 1, and an additional metering choke 8 installed in the second l lines 6 (the names of the metering chokes are primary and secondary. These chokes differ in conductivity values: for example, the conductivity of the main choke 7 is greater than the conductivity of the additional metering choke 8). The hydraulic system is also equipped with two check valves 9 and 10. The first check valve 9 is installed in the first line 5 after the main metering choke 7. The second check valve 10 is installed in the second line 6 before or after the additional metering choke 8. The second line 6 is connected to the first line 5 after check valve 9.

The control means for the movement of the spools of both the primary and secondary valves are not significant to the essence of the invention. They may be the same or may differ from each other. The diagram shows, by way of example, electro-hydraulic control in relation to the auxiliary valve 4. The control cavities 11 of this valve are connected to the discharge line 1 through identical chokes 12 and simultaneously communicate with the drain via shut-off valves 13.

The proposed hydraulic system is also equipped with a known coca unloading device. It is made in the form of an overflow valve 14 with a throttle 15 in the control line 16, connected with the drain through the shut-off valve 17. The control line 16 is connected to the first line 5 after the metering chokes 7 and 8.

The proposed hydraulic system operates as follows.

To obtain the minimum speed of the executive

5 hydraulic motor 3 supply voltage to

electromagnet of the lower valve 13. When

this lower cavity 11 additional

.. the distributor 4 communicates with the drain, and

fluid flows through the bottom

0 throttle 12. Due to the pressure drop arising on this throttle, the pressure in the lower control cavity 11 becomes lower than in the upper. The spool of the auxiliary distributor 4 is shifted downwards

5 and the top position is set. Simultaneously with the supply of electric voltage to the electromagnet of valve 13, means for controlling the movement of the spool of the main distributor 2 are activated, which is set to one of the operating positions, and the voltage is applied to the electromagnet of the shut-off valve 17 of the pump discharge device. Overflow of the entire pump supply to the drain through

5 overflow valve 14, which takes place at idle operation of the hydraulic system. Oil is pumped into one of the working cavities of the hydraulic motor 3 through an additional metering throttle 8, conductivity

0 which is less than that of the main metering throttle 7. The minimum speed mode of operation of the hydraulic motor 3 is established. At the same time, the non-return valve 9 prevents the liquid from flowing back.

5 through the main metering throttle 7. A pressure signal indicating an external load on the actuator hydraulic motor 3, through the control line 16 enters the spring-containing cavity

0 overflow valve 14, which maintains the constant differential pressure on the additional metering throttle 8, thereby stabilizing the set minimum speed mode of operation of the 5 hydraulic actuator.

The average flow rate mode is realized with the neutral position of the spool of the additional distributor 4. The remaining actions are similar. In this case, the working fluid is pumped into the hydraulic motor through the main metering throttle 7 installed in the spool of the distributor 4. Having received a load pressure signal, as described above, the overflow valve 14 allows to stabilize the flow of the working fluid, therefore, the speed of the hydraulic motor corresponding to the conductivity of the main metering throttle 7.

If it is necessary to obtain the maximum speed mode of operation of the hydraulic motor, an electric voltage is applied to the electromagnet of the upper valve 13. The remaining manipulations are similar to those described with respect to the case of the minimum speed mode. In this case, the lower position of the spool of the additional distributor 4 is set to the working position. The oil is pumped into one of the working cavities of the hydraulic motor 3 unhindered, bypassing the metering throttles. Since the pressure in both control cavities of the overflow valve 14 is equal, it completely closes under the action of its spring, and the entire pump flow rushes to the hydraulic motor. The non-return valve 10 prevents the discharge line from communicating with a drain through an additional metering throttle 8.

The invention allows to expand the functionality of the hydraulic system, providing multi-mode operation. As a result, the working conditions of the operator are improved, the productivity is increased, and the quality of the process is improved. The possibility of a high degree of unification creates prerequisites for increasing reliability and lowering the cost of the system.

Claims (1)

SUMMARY OF THE INVENTION A hydraulic system of an agricultural machine comprising a delivery line with a pump and a main metering throttle connected to a first line of a main spool three-position four-line distributor, a second line of which is connected to a drain, and a third and a fourth line are associated with corresponding cavities of the actuating hydraulic motor, and a pump unloading device comprising a control line connected to the discharge through the shutoff valve and connected to the discharge line mainly of the metering throttle, characterized in that in order to extend the operational capabilities, increasing the performance and reliability of the hydraulic system, it is provided two non-return valves, an additional metering throttle and an additional spool three-position four-way distributor, in the spool of which the main metering throttle is located, the first and second lines are connected to the first and second lines of the main spool three-position four-line distributor directly, and the third and fourth to the first line the latter through the first non-return valve and sequentially connected to the second non-return valve and an additional metering throttle, respectively, while in the first position of the additional spool three-position four-way distributor, the first line is connected to the fourth, and the second to the third, in the second position all lines are muted, and in the third position of the first line is connected to the third, and the second with the fourth.