SU1257144A1 - Hydraulic drive for power shovel working equipment - Google Patents

Description

12

The invention relates to earthmoving machines, namely their hydraulic actuators.

The aim of the invention is to ensure the reliability of the hydraulic actuator due to the continuous automatic adjustment of operating modes depending on the load on. earth moving body, simplifying control, eliminating stop modes in operation, overloads and pressure fluctuations in the hydraulic system.

FIG. 1 shows a basic hydraulic drive circuit; in fig. 2 - hydrokinatonic drive scheme; Fig. 3 is a diagram of the hydraulic drive of the working equipment with automatic and manual control; in fig. 4 - hydrokinematite-geska scheme of the working equipment of the excavator.

The hydraulic actuator includes a pump 1, hydraulic cylinders 2 and 3 of the boom and their connecting rod 4, hydraulic cylinder 5 of the handle, control throttles 6 and 7, check valves 85 hydraulic valves

lindra 9 buckets and distributors 10-16

four

LIQUID.

The speed and direction of movement of the cutting edge of the bucket depends on the magnitude and direction of the angular velocities of the boom QP and the arm QP 5 which, in turn, depend on the accelerating moments with i (9o) (0f)

Accelerating moments 5 respectively to the boom to the hilt, equal to

thirty

the ratio of the moments given to the corresponding links, due to the forces of resistance to digging and the forces of the hydraulic cylinders. Since the fluid pressure in the piston cavities of the hydraulic cylinders of the handle and the boom is the same, the piston movement will be greater than the hydraulic cylinder where the load on the rod is less.

Hydraulic drive cost equation is written

35

.. ,,, 4Y, .i,

(four)

The speed of the cutting edge of the bucket is equal to (Fig. 2)

, 4 |. RH go- xxo5i nao- A;

®p ° 8P5 r f «5S - A p and force is applied to the rod 4

 CRN-1P, ..- Kg,

Where

(ABOUT

(21

40

. C-VCA V ,,, (5),

Analysis of equations (1-5) implies that, due to an increase in the load on the rod of one of the hydraulic cylinders (booms or arms), the fluid consumption in this hydro-sian-V .- (x indre, but taking into account equation 4, with

constant pump power in another cylinder will increase fluid flow, i.e. the speed of the piston of the other cylinder will increase.

Thus, an increase or

reducing the load on the stock one

out of the hydraulic piston heads (arrows or arms), respectively, they lead me away (I

p .- momentum conditioned by forces to press the arrows to the bottom;

50

Mud, Mdr-moment reduced to the boom and the handle, respectively: енноенноенно С С С С С С С С С вес;

M-Mj - reduced moment of tangential and normal composition or reduction of the speed of other digging force; 55 ro hydraulic cylinders (respectively, static moments of resistance or arrows). But since the events are relative to the axis of rotation of the boom and arm;

the load on the hydraulic cylinder rod mainly depends on the resistance forces

s

0

2

M.g, Mj- is the reduced dynamic forces of inertia of the boom and arm;

 - the moment of rotation of the handle, due to the force of the hydraulic cylinder 5; PH - pump pressure;

Гп |, 1у |, п ,,. the areas of the piston and rod cavities of the respective hydraulic cylinders (Fig. 1) ;, Py, Pd, Pp — pressure in the respective I cavities of the hydraulic cylinders; Kg is the damping coefficient; Fjjj - resistance to piston movement.

 Taking into account that the dynamic moments of M: and Mjp are equal to zero, M ,, con5-t, MQO and Mor Mpr drive power are constant, we can assume that the accelerating moments

and

mainly depends on

the ratio of the moments given to the corresponding links, due to the forces of resistance to digging and the forces of the hydraulic cylinders. Since the fluid pressure in the piston cavities of the hydraulic cylinders of the handle and the boom is the same, the piston movement will be greater than the hydraulic cylinder where the load on the rod is less.

Hydraulic drive cost equation is written

35

.. ,,, 4Y, .i,

(four)

The speed of the cutting edge of the bucket is equal to (Fig. 2)

the load on the hydraulic cylinder rod mainly depends on the resistance forces

digging, the operating mode of the hydraulic mechanism of the excavator's working body will be determined through the process. A change in the manufacturing process affects the kinematic mode of operation and vice versa.

In automatic mode, the hydraulic actuator works as follows.

Example 1. The cutting edge does not touch the ground surface, i.e. RP О, Рц 0. The pressure in the hydraulic system in this case is minimal and due to the load from the forces of the weight of the working equipment. In this case, the magnitude of the reduced force of the weight to the rod of the hydraulic cylinder of the arm is less than the force of the rod of the cylinder of the boom. Therefore, the piston of the hydraulic cylinder 2 will fall down and the boom will rotate clockwise.

The fluid displaced from the rod end of the hydraulic cylinder 5 will flow into the rod cavity of the hydraulic cylinder 3. The body of the hydraulic cylinder 3 under the action of fluid pressure in the rod cavity and the weight of the equipment will move relative to the rod 4, displace the liquid from the piston cavity of the hydraulic cylinder 3, and rotate the boom clockwise, while providing the necessary compression of the body to the bottom. Consequently, the velocity vector V will be directed toward the side (Fig. Ab). The rod 4 moves relative to the cylinder body 2, depending on the magnitude of the reduced force b,. The speed of movement of the rod is regulated by the choke 6.

Example 2. When bucket encounters an insurmountable obstacle or in case of excessive burial

The resistance forces R and R will be equal to 1 rd, g, and RH, respectively. The speed of the piston of the hydraulic cylinder of the handle will become zero, therefore, the pressure P in the rod cavity will become equal to some fixed pressure.

The pressure in the discharge line of the pump will reach the value of n max. will increase (3) and the rod 4, overcoming the resistance of the drossel 6, will increase the speed of movement by increasing the volume of the rod cavity of the hydraulic cylinder 3. At the same time, the pressure of PSH-, in the rod cavity of the hydraulic cylinder 3 decreases, decreases and

s 12571444

power up your arrows. Under the action of the normal and tangential components of the resistance of the soil to) 0

20

th

25 30

the start of the work equipment will begin. With increased speed V,,. taking into account the hydraulic resistance of the throttle 7, there will be a pressure in the piston cavity of the hydraulic cylinder 3, and, consequently, an additional force,. . aimed at boom lift. As a result of the effect of the listed forces, the arrow, turning counterclockwise, will retract the cutting edge of the bucket from the bottom at a speed of US, (Fig.46) .. At the same time, under the action of the hydraulic cylinder of the handle, the cutting edge will to press against the face, to the obstacle with a certain effort. As can be seen from the velocity plan (Fig. 4b), the cutting edge of the bucket will tend to circumvent the obstacle without rubbing contact with it, or reduce the chip thickness. If the obstacle is bypassed or resistance is reduced to normal, the process of cutting the soil will continue.

Example 3 (working). Depending on the chosen mode, soil development, i.e. taking into account the strength of the soil, the height of the nomogram establishes the working pressure of the nom. After the bucket is led to the face, separate distributors are turned on to connect the hydraulic cylinders using a dual differential circuit. moving the handles will force the liquid out of the rod cavity under pressure and force it into the rod cavity of the hydraulic cylinder 3. In this case, the hydraulic cylinder

5 3 creates the necessary effort to press the working equipment to the face, i.e. bucket burial occurs.

With increasing chips will increase the resistance fip and, accordingly,

0 increase pressure R., in hydro5

0

system,

SR P

since g

When reaching th „P

ry thickness

five

- HOW chip increase will stop and normal digging will begin. In the event of a change in the load (change in chip thickness due to unevenness of the bottom, change in the strength of the soil, various inclusions), the hydraulic mechanisms

The NIZM will work this way (see, example 1 or 2) so that the specified load on the bucket edge does not change. By performing non-continuous automatic control of the cutting edge of the bucket, it is possible to provide a constant nominal or slightly different from the nominal pressure at the time of transition processes in the hydraulic system, to exclude stop modes, sharp fluctuations in pressure drops.

57144 "&

To operate the hydraulic drive in manual mode, all control valves are installed in position B. In this case, the fluid from pump 1 through hydraulic distributors, dividers 10, 15, 11, 12 and the control valve 13 is connected to a drain cavity, i.e. with the control valves not turned on, the pump is not loaded. K) The LD1 of setting in motion any working equipment link is necessary. Dimo enable the corresponding valve.

Wo

CSS

VCB

VCA

Editor N. Slobod Nick

Compiled by S. Fomin

Tehred M. Morgental Proofreader V, But ha

Order 4887/23 Circulation 641 Subscription

VNISHI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

HYDRAULIC DRIVE OF WORKING EQUIPMENT OF A SINGLE SHAFT EXCAVATOR, including a pump unit, boom, stick and bucket hydraulic motors with their hydraulic distributors and hydraulic lines / characterized in that, in order to increase the reliability of the hydraulic drive, the boom hydraulic cylinder is made in the form of two hydraulic cylinders the cavity of the first of which and the rod cavity of the second are connected to the drain each by means of a parallel-mounted adjustable throttle and check valve, while the rod cavity of the hydraulic motors tor arm communicates with the stem cavity of the first boom cylinder and a piston - piston cavity with the second boom cylinder.