CN1130726A

CN1130726A - Line structure for preheating hydraulic circulation

Info

Publication number: CN1130726A
Application number: CN95118149A
Authority: CN
Inventors: 伯德·恩德尔
Original assignee: MAN Takraf Fordertechnik GmbH
Current assignee: Takraf GmbH
Priority date: 1994-11-04
Filing date: 1995-11-01
Publication date: 1996-09-11
Also published as: CA2161619A1; RU2140022C1; DE4439454A1; DE4439454C2

Abstract

The preheating of hydraulic systems is prior art. It is generally done by operating the system without load until the prescribed minimum temperature is attained. However, in the known types of preheating circuits the operating elements (hydraulic cylinders) are not included. The invention relates to an arrangement in which the operating elements are included in the heating circuit. Appropriate circuits are provided for the various operating states of the hydraulic cylinder, i.e. 'neutral', 'retract piston rod' and 'extend piston rod'. The provision of an additional passageway in the piston rod through which the hydraulic oil can pass into the hydraulic cylinder is an essential feature by means of which the oil can circulate without the pressure while the system is in the neutral operating state. By using the invention, it is possible to preheat hydraulic circuits in the neutral, non-operating state, thusavoiding damage to the operating elements, increasing the lifetime of the wear parts and guaranteeing reliable operation of the hydraulic system. The inventionis suitable in particular for use in conveyor systems operating in cold regions.

Description

Pre-thermohydraulic circuit line construction

The present invention relates to a kind of line construction, be used for the hydraulic pressure circulation that preheating comprises drive unit, with the reliability of assurance function and work.This line construction is particularly useful for the hydraulic equipment of working under low ambient temperature, for example the conveying equipment that uses at cold area.

Known hydraulic equipment of working under low ambient temperature by preheated liquid container or pipeline and the pipeline of purge in no pressures cycle, makes this equipment be in the preparation running state.By the method and apparatus of known a kind of heating of DD-PS 268044 or cooling hydraulic tubing, wherein, for preheating, by the circuit hot air, heating one section of pipe-line system in the two-chamber passage.At this moment, hydraulic fluid is crossed this pipe-line system by the hydraulic pressure pump pressure in circulation, and keeps operating temperature.For example in the zone before the oil hydraulic cylinder, be provided with a bypass valve in abutting connection with operation mechanism in the connecting pipe between input pipeline and reflux line, reflux by this bypass valve hydraulic oil.

For avoiding operation mechanism to be subjected to uncontrollable the influence, always adopt a stop valve that input is separated with reflux line and operation mechanism.Therefore the hydraulic fluid in operation mechanism is excluded outside heating circuit.So when operation mechanism moved, the hydraulic fluid of heating flowed in the cold operation mechanism, and cause functional fault or increase wearing and tearing.Under extreme case, even may produce thermal shock, this means to produce serious stress.Have only when the even heating of equipment finishes, the function that causes is therefrom disturbed died away.

More rare and operation mechanism of short-term operation just for those, owing under cold ambient temperature, can not or just seldom can reach even heating (heat penetration), so disadvantageous operating conditions is preponderated.

Therefore, the objective of the invention is to avoid these shortcomings.

By the present invention is that to reach the measure that this purpose takes be by the described feature of claim 1 characteristic, oil hydraulic cylinder to be included in the hydraulic equipment of wanting preheating in the circulation.

This special hydraulic pressure circulation is used for following three kinds of states:

-no pressures cycle;

The withdrawal of-piston rod; And

-piston rod stretches out, and these are disclosed in the claim 2,3,4.

Advantage of the present invention is, when cold area uses conveying equipment and instrument, and for guaranteeing functional reliability and reduce wear, can the whole hydraulic system of preheating, and therefore normal operating conditions is arranged all the time.

Represented embodiments of the invention in the accompanying drawings, and elaborated below.Wherein:

Schematically illustrating of the brackets with height-adjustable of Fig. 1 conveying equipment; And

Fig. 2 is used for the circuti diagram by simple Hydraulic for lifting load device shown in Figure 1.

Fig. 1 has represented a support 1, and it for example is used for excavator, bulldozer or similar machinery as the discharging support.This support 1 can be swung in the horizontal direction by a drive unit that does not further describe, and can turn round along short transverse by oil hydraulic cylinder 2.In this case, oil hydraulic cylinder 2 is subjected to pulling load.

At the circuti diagram that is used for simple Hydraulic for lifting load device shown in Figure 2, the symbol that each functional element is used is necessary for this class circuit, and this line principle is disclosed to the professional workforce in this field work.Therefore, further specify these functional element and the mode of action in hydraulic system is unnecessary.

Also should remark additionally is characterized in, the superpressure that pressure-limit valve VD1 can not allow in being used for preventing to circulate, and the filter F that has bypass VR3 is used to clean the liquid of backflow, and throttle valve VDr1 is used to limit rate of descent.

In addition, what Special Significance was arranged also has, and the piston rod 4 of the oil hydraulic cylinder of representing with symbol M Y1 commonly used in the circuti diagram of Fig. 22 has a passage that extends longitudinally 6.

In no pressures cycle, pump P1 with oil 3 from fuel tank T through selector valve VW1; P → A is by piston rod 4 passages 6 of oil hydraulic cylinder MY1, input piston chamber 5.At this moment, safety check VR2 is open.The oil 3 that comes out at the joint A place of oil hydraulic cylinder MY1 is through the neutral position that selector valve VW2 opens; AB → T flows back to fuel tank T.

Under this situation, the hydraulic oil 3 of preheating is passed to clutch release slave cylinder MY1 with heat.In addition, the pressure of opening of safety check VR2 produces additional temperature, and this produces positive influence for whole working method.

" decline " function is by selector valve VW2 control.

For this reason, magnet a is encouraged by selector valve VW1, and forms connecting passage P → A; B → T.Meanwhile, the magnet a that has encouraged of selector valve VW1 closes no pressures cycle.

The oil 3 that comes out from selector valve VW2 flows into piston cavity 5, and this piston cavity 5 is sealed by safety check VR2 now.The pressure of being set up is opened safety check VR1 by pressure-limit valve VD2.At the oil 3 that the differential side of oil hydraulic cylinder MY1 is come out, can be through the connecting passage of selector valve VW2; B → T flows back to fuel tank T.Oil hydraulic cylinder MY1 stretches out.

When the electromagnet a of selector valve VW1 and VW2 outage, process finishes.Pilot pressure can descend by flow controller VDr2, and safety check VR1 pins oil hydraulic cylinder MY1.

" lifting, " function is by selector valve VW2 control.

For this reason, magnet 6 is encouraged by selector valve VW1, and forms connecting passage P → B, A → T.Meanwhile, the magnet a that has encouraged of selector valve VW1 closes no pressures cycle P-1, T-1.

Oil 3 comes out from the channel B of selector valve VW2, and flows into rod end chamber 7 through safety check VR1.The oil 3 that comes out from piston one side of oil hydraulic cylinder MY1 is through the connecting passage of selector valve VW2; A → T flows back to fuel tank.Oil hydraulic cylinder MY1 withdrawal.

Claims

1. preheating is at the conveying equipment hydraulic pressure circuit line construction of cold area use, and by the assurance of purge pipeline in no pressures cycle functional reliability, wherein can stipulate the container of pre-deep fat, it is characterized by: one or several oil hydraulic cylinder (2) is included in the warm-up cycle, for this reason, in piston rod (4), establish additional overflow ducts (6), piston cavity (5) additionally is communicated with pipe-line system through this passage (6), by some set for this reason valves, for the withdrawal of no pressures cycle and piston rod (4) with stretch out and connect independent circulation.

2. according to the described pre-thermohydraulic circuit line construction of claim 1, it is characterized by: when no pressures cycle, by the valve in the circulation loop, make oil (3) from the passage (6) of fuel tank (T) through piston rod (4), enter in the piston cavity (5) of oil hydraulic cylinder (MY1), return in the fuel tank (T).

3. according to the described pre-thermohydraulic circuit line construction of claim 1, it is characterized by: in order to stretch out piston rod (4); Oil pump pumps into oil (3) the piston cavity (5) of oil hydraulic cylinder (MY1) from fuel tank (T), and when (anliegend) pressure that requires, oil overflow (3) can flow back to fuel tank (T) from rod end chamber (7), and, make by closeall valve and to stretch out release.

4. according to the described pre-thermohydraulic circuit line construction of claim 1, it is characterized by: for the piston rod of withdrawing (4), by hydraulic oil (3) is introduced rod end chamber (7) from fuel tank (T), meanwhile hydraulic oil (3) extrudes from piston cavity (5) and enters fuel tank (T), and, finish the withdrawal action by closeall valve.