Calculation of hydraulic diagram of LPC excavator

Contents

Contents

Introduction

1 Drawing up of hydraulic diagram and its description

2 Determination of prime mover power

3 Determination of pump unit parameters

4 Determination of geometrical parameters of operating equipment

5 Determination of power consumption of operations and selection of power

hydraulic cylinders

5.1 Digging by turning the handle

5.2 Digging by bucket turning

5.3 Lifting of operating equipment

6 Calculation of turning mechanisms

Literature

Appendix 1: hydraulic diagram of excavator, f. And

Appendix 2: design diagram of the excavator, made on a scale of 1:40, f. And

Appendix 3: hydrokinematic diagram of the platform rotation mechanism, p. And

Introduction

The main type of machines for earthworks and cargo transportation are single-bucket excavators and hydraulic-driven cranes. Compared to the cable drive, they have a number of advantages of a structural, technological and economic nature.

From a constructive point of view, the hydraulic drive allows to realize large gear ratios from the leading link of the energy source to the working mechanisms and organs of the machines without using bulky and complex kinematics devices; provide simple conversion of rotational motion into translational motion; to have independent arrangement of power source and working mechanisms, as well as to carry out convenient and independent control of speeds of working movements in wide range.

From a technological point of view, the conditions for filling the ladle when digging at great depths are improved due to the ability to realize large digging forces, as well as due to the rotation of the ladle relative to the handle at the end of the digging process. This increases the productivity of the excavator.

Economic advantages are the result of structural and technological advantages, which ultimately increase the pace of construction and other types of work and reduce the cost of developing soil or moving cargo.

These advantages of the hydraulic drive have led to its widespread use in machines of various purposes, and primarily in earth-moving ones. Therefore, successful operation of such machines requires a sufficiently high level of training in hydraulic drives. This goal is served by the course work provided for in the curriculum for the design of the hydraulic system of a single-bucket excavator.

Initial data: q = 0.55m 3;

Operating equipment - reverse shovel

Selection of hydraulic circuit and its description

The schemes used are divided into single- and multithreaded. Single-flow schemes are used only on incomplete excavators with a ladle capacity of up to 0.3 m3.

In order to reduce the cycle length by combining work operations, we adopt a double-flow system.

The scheme provides for the possibility of working with a reverse shovel, loader and grapher. It includes two pumps, two hydraulic distribution units, hydraulic distributors for turning the grab and the tracking wheel turning system, hydraulic motors for turning the platform and moving the excavator, as well as hydraulic cylinders: handles, booms, a bucket of a reverse shovel, turning the grab and turning the wheels.

Main mechanisms are driven by two-section automatically controlled axial-piston pump. The second pump (gear, non-adjustable) is used to supply hydraulic cylinders for turning the grab and turning the wheels.

From sections A and B of pump working fluid is supplied by parallel flows to hydraulic distribution units respectively and from them to supply hydraulic motors. The exception is the working section P7, which is separate from all other power sections due to the use of the intermediate section.

Actuation of an excavator mechanism is performed by means of corresponding three-position spools. In the position shown in the figure, all spools are in neutral position. In this case, both pump sections feed the full flow to the hydraulic distribution unit. When any of the spools of the hydraulic distribution unit is switched on, liquid flows from sections A and B are disconnected and the unit is supplied only from pump B.

The full flow can also be supplied to the hydraulic cylinder of the handle when actuated from the hydraulic distribution section P7. However, if it is necessary to combine operations, it can be turned on through the spool of the SR section. In this case, the flows are disconnected and this makes it possible to combine the movement of the handle with the movement of the boom or the bucket of the reverse shovel.

When working with the grapher, the operating hydraulic lines of the reserve section P2 are used to control the hydraulic cylinder for lifting (lowering) the upper part of the composite boom, section P6 - for controlling the hydraulic cylinder of the grapher jaws, and the hydraulic distributor for turning the grapher - for controlling the hydraulic cylinder for turning the grapher.

Operating fluid is drained to the tank from all hydraulic motors through the slide valve. With this spool, the flow can be directed either to the cooler, if necessary, or bypassing it to the filters installed in parallel.

In case of their clogging, the flow can be bypassed through safety valves into the tank past the filters.

The number of filters installed in the drain line is determined by the need to provide minimal resistance to fluid flow.

Pressure hydraulic lines of both sections of pump 1 and pump 13 are protected against pressures exceeding permissible ones by means of safety valves. Besides, check valves are installed in pressure hydraulic lines of sections A and B of pump 1.

Safety and check valves are installed in operating hydraulic lines of motors, as well as hydraulic cylinders. The first of them serve to protect against permissible pressure. Through the second, make-up or bypass of working fluid from one hydraulic line to another can be carried out when the safety valve is actuated.

To control the setting of safety valves, a pressure gauge is installed in pressure hydraulic lines, which can be alternately connected to the pressure lines of sections A and B of pumps. In a drain line, the pressure can be controlled by a pressure gauge.

рсчетная схема экскаватора.dwg

схема поворота.dwg