DE2303200A1 - EARTH CONSTRUCTION VEHICLE, IN PARTICULAR EXCAVATOR - Google Patents

Description

DR. BERG DIPL.-ING. STAPF

PATCHTAN WXLTIC • MUNICH «O. MAUERKLRCHEITSTR. 4 *

230320Q

Lawyer File 23 335

U Jan. 1973

KUBOTA TEKKO KABUSHIKI KAISHA Osaka / JAPAN

Earth-moving vehicles, in particular excavators

The invention relates to a lifting and conveying vehicle for earthworks and the like with a means of at least a hydraulic motor that can be raised and lowered and at least two hydraulic fluid supplying pumps. The invention particularly relates to such an excavator such as one Universal excavator or a backhoe. The invention also includes a corresponding crane. The invention is particularly suitable for excavators such as backhoe excavators, in which all tool movement is done by hydraulic motors, usually and preferably are designed as cylinder-piston assemblies.

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In hydraulic excavators such as backhoes, the volume of the boom raising and lowering is the volume Hydraulic cylinder particularly large. Accordingly, you need to lift the boom by means of the hydraulic cylinder A lot of hydraulic pressure fluid in a short time, as the lifting process takes place quickly target. For this purpose you can use the hydraulic motor to raise and lower the boom with hydraulic fluid feed from both pumps at the same time. Due to the correspondingly increased amount of liquid per unit of time the lifting and lowering speed is increased accordingly.

In this way, the heavy weight of the boom with the excavator bucket is taken into account when lifting it quickly carried. When lowering the boom, the weight of the boom and the weight of the bucket and the excavated soil in the same direction as the adjusting force exerted by the actuating motor, so down. The rapid application of the servomotor when lowering the boom with a large one However, the amount of hydraulic fluid poses a risk to the excavator operation due to the added force of gravity when lowering the boom, it is therefore desirable to use the force acting in the direction of lowering of the hydraulic motor to keep the lowering speed low not to let it get too high. Accordingly, it is sufficient if only when lowering

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a pump acts on the hydraulic motor

In this way, lifting can be done quickly while feeding the hydraulic motor from two pumps lowering while feeding the hydraulic motor with hydraulic fluid from just one pump is sufficient slowly happens.

In machines such as excavators, especially shovel excavators, where the boom is raised and lowered takes place by means of a winch, which is operated by a hydraulic motor, the invention also apply accordingly.

The invention can be implemented with a simple hydraulic switching arrangement. She lets herself too modify many times. For example, it is possible to use backhoe excavators that normally have three hydraulic cylinders for have the execution of all bucket movements, not just the lifting motor for the boom Cylinder according to the invention to act differently, but also one or both of the others Cylinder. The drive is then in each case so that for the implementation of the work movements, which against high resistance (gravity, but possibly also resistance of the ground), both Engines work on the corresponding cylinder,

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while with the movements made by gravity supported, only one motor works on the corresponding hydraulic cylinder. With appropriate training the device, it is also possible to partially, for example over the second, additional pump adjustable throttle elements to be switched on.

The invention can be implemented relatively easily by having the second pump via a corresponding one Control valve and a check valve with the feed line of the respective hydraulic motor connects which actuate the tool or the corresponding tool part against increased resistance Has. In this way, hydraulic fluid can only be fed into the inflow line for this actuation direction can be supplied by both pumps. When charged of the motor over the line for the opposite In the working direction, the motor is acted upon by only one pump. The outflowing hydraulic fluid can also only flow out through one line, as there is an outflow through both lines of the mentioned Check valve is prevented.

It will be understood that hydrostatic or volumetric pumps and motors are preferred in the invention be used.

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The invention makes it possible to achieve the following advantages:

I, while working the tool or tool part against increased loads, such as when lifting the boom, both pumps can work on the corresponding motor · This way the lifting speed elevated. Nevertheless, when lowering or working against reduced resistance, a undesirably strong acceleration of the tool or tool member, such as due to gravity, avoided. A quick lifting and a safe lowering become safe and easy in this way achieved.

II. When the control valve is in the blocking position for switching the second pump on and off, it is only possible to use a drive pump can be operated slowly. Accordingly, there is a choice between fast and slow working stroke possible.

III · If you use a valve to switch the second pump on and off, which is not only used for blocking, but is also suitable for reversing, so each of the two can of this control valve in the direction of the motor leading lines to operate another

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hydraulic motor can be used as for the return of the supplied by the second pump Liquid no separate return line is required.

Below is the invention in the form of a preferred one Embodiment described with reference to the schematic drawing.

Fig. 1 shows a side view of a hydraulic backhoe excavator according to the invention.

Fig. 2 shows the hydraulic circuit diagram of this excavator.

The undercarriage of the excavator shown has two crawlers 2 and 2 · driven by two hydraulic motors 1 and 1 * are driven. A hydraulic motor 3 is used to rotate the superstructure 4 A hydraulic cylinder 5 serves to lift and lower the boom 8 against the upper carriage 4 A hydraulic cylinder 6 is used to pivot the dipperstick 9 around the end of the boom. The bucket 10 is turned around the end of the dipperstick 9 is pivoted by means of a hydraulic cylinder 7.

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The more precise puncture of the invention is explained below with reference to FIG. There are also the motors 1, 1 ^f , 3 »5, 6 and 7 as well as the two pumps P-. and Pp and an oil reservoir T are shown. As can be seen from FIG. 2, one or two pumps feed _{one or more motors via one or two of the control valves V-, to V 7} , in that they supply hydraulic fluid sucked in from the container T under corresponding high pressure to the respective motor or motors from which the hydraulic fluid flows back into the container T via the corresponding control valve.

In the exemplary embodiment, all control valves V- to V _{7 have} three switching positions, namely a blocking position for the associated inlet and outlet line, which is indicated in the middle, an open position, which is indicated in the left part of the valves, and a reversing position, which is indicated in the right part.

The pump P- is connected to the control valves V- ,, Vp and V ^ by means of corresponding inlet lines. The control valves are connected to pump 1 in parallel with one another. The control valve V ₁ is used to act on the first traction motor 1. The control valve Vp is used

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the application of the bucket servomotor 7 and that Control valve V ^ the application of the boom lift motor 5 · A corresponding return line leads from each motor through the associated valve to the storage tank T.

The pump P _? supplies pressure oil via parallel lines to the control valves V., V _c and V, .. The control valve V. regulates the application of the second traction motor 1 *. The control valve V, - regulates the application of the hydraulic cylinder 6 for the dipperstick 9, while the control valve Vg regulates the application of the rotary motor for the superstructure. Here, too, a return line leads from each of the motors through the associated control valve back into the storage container T, as shown in the drawing. It can be seen from the drawing and the direction of the arrow in the symbolic representation of the valve that all motors can be reversed by optionally connecting one or the other of the lines from the control valve to the motor to the feed line coming from the associated pump.

In parallel with the control valves V., V ₁ - and V _g , a further control valve V ₇ of the same design is connected to the pump Pp. A line a leads from the two outlet connections of this valve V ₇

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Liquid only from the valve, but not to the valve .hin allowing check valve Vg to line c, which the control valve V, with the side of the hydraulic cylinder 5 connects, when they are applied, the piston is pushed out of the cylinder and thus the Boom 8 is raised.

The second outlet line b of the control valve V ₇ leads via a non-return valve corresponding to the valve Vo, which also prevents the return flow to the valve V ₇ , to the line d, which connects the control valve Vp with the chamber of the hydraulic cylinder 7 The cylinder is pushed in and the spoon is swiveled clockwise in the drawing.

From what has been described so far, it follows that the various motors are independent with the aid of the valves V .. to Vg hydraulic fluid can be applied to each other so that they each carry out the working movement in the desired direction. the The control valves can be operated manually or electromagnetically take place.

To raise the boom 8, both the valve V-. as well as the valve V ₇ in the forward position

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be brought, in which pressure fluid flows from the pump P ₁ via the line c in the left part of the hydraulic cylinder 5 in Fig. 2 and hydraulic fluid from the pump Pp via the line a and the check valve ^ also into the line c and thus the left Part of the hydraulic cylinder 5 is fed. The hydraulic cylinder 5 accordingly pushes its piston out quickly, since it receives practically twice the amount of pressure fluid. Thus, the boom 8 is swiveled quickly upwards.

The same pivoting movement of the boom 8 can, however, also be carried out if the control valve V _{7 is left} in the blocking position shown in the drawing. Then the lifting of the boom 8 takes place only slowly and exclusively by means of the pump P-.

To lower the control valve V, in his right part shown reversing position brought at which pressure fluid is supplied to the right part of the hydraulic cylinder 5 in the drawing, so that the piston is retracted and thus the boom 8 is lowered. From the left in Fig. 2 space of the hydraulic cylinder 5 hydraulic fluid now flows through valve V-. back to the reservoir T. A backflow Via the valve Vq and the line a is in no way possible, since the valve Vo controls the flow

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locks in this direction. Thus, the lowering of the bar takes place exclusively by means of the pump P-,. Of the Backflow of hydraulic fluid from the emptying cylinder part only takes place when lowering one line and therefore slow. When lowering, of course, gravity also acts accordingly with. However, an acceleration of the movement by hydraulic fluid from the second pump P "is avoided.

In the invention, in parallel with the control valves Vj, V ₂ and V-. an eighth control valve of the same type as the control valve V ₇ can be cut. If this control valve, which is not shown in the drawing, is connected to the right part of the hydraulic cylinder 6 for the dipperstick 9 in FIG additional valve, not shown, the pump P-, also supplies pressure fluid into the cylinder 6 so that its piston is retracted.

The hydraulic cylinder 7 pushes its piston out during the shoveling work of the bucket 10 and pulls it when emptying the spoon. In both cases, the hydraulic cylinder 7 is acted upon by

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of the pump P-, through, corresponding position of the valve Vp. To swivel the spoon 10 clockwise, _{i.e. to empty it, the pump P 2 can also be switched} on via the valve V ₇ to the feed line d, which the piston in the cylinder 7 pushing pressure oil delivers »For this purpose, the valve V _{7 is brought} into the reverse position, in which the pump P _? incoming pressure oil line is connected to line b from valve V ₇ to line d. As a result, the spoon 10 is emptied very quickly.

Instead of connecting line b to line d, line b can also be connected to line d ^f , through which oil pushing out the piston of cylinder 7 is fed into the cylinder. With such a connection, the digging work of the excavator is carried out at increased speed.

In both cases, the hydraulic fluid flows out of the cylinder chamber, which is not acted upon by both pumps, only through one line, since the valve V _q prevents backflow.

The construction can be made so that the valve V ₇ inevitably cooperates in each case. she can

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but also be made so that the excavator operator can choose to switch on the valve V ₇ and thus the second pump or not.

The control valves V-, "to V ₇ can be slide valves with three switching positions or rotary valves.

The control valve V ₇ can be switched on its own. However, it is more advantageous if this valve is designed to be switchable at the same time as the valves Vp and V,.

A two-stage circuit is also possible for the boom lift. _{In the first stage only the control valve V 1} is actuated, so that the hydraulic cylinder 5 is only acted upon by the pump P 1. For the second working stage, the control valve V _{7 is} additionally actuated, so that the hydraulic cylinder 5 is acted upon by both pumps P. and P ".

The control valve V ₇ can also have more than just three switching positions or more outlet connections than two. This allows the control valve to be used to accelerate several hydraulic drive motors.

- patent claims -

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Claims (2)

230320Q Patent claims: ί 1. lifting and conveying vehicle for earthworks and the like, in particular excavators, with a tool that can be raised and lowered by means of at least one hydraulic motor, and at least two pumps delivering hydraulic fluid, characterized in that the hydraulic motor when working in one direction, in which the force of gravity acting on the tool acts in the same way, only one pump (P.,) is charged with hydraulic fluid that the second pump (P ₂ ) with the hydraulic motor (5) via a control valve (V ₇ ) and a check valve (Vn) preventing a backflow of liquid to the motor is hydraulically connected, and that the control valve (V ₇ ) also allows the second pump (Pp) to be connected to the hydraulic motor (5) when the latter is the tool in the Direction of gravity moves opposite direction. 2. Vehicle according to claim 1, characterized in that. that several hydraulic motors (1, 5, 7) driven by the first pump (P ₁ ) are provided, that at least one of these motors is connected to the second pump (P _{2 ) via the control valve (V 7} ), that the control valve ( V ₇ ) at least three switch positions - 15 3098 3 2/0446 230320Q has that in a first switching position of the control valve (V ₇ ) the pressure oil outlet of this valve (V ₇ ) is connected to the pressure oil feed line (c) of a hydraulic motor (5) driven by the first pump (P-) via the check valve (Vo) and that the second oil outlet connection of the control valve (V ₇ ) is connected to the pressure oil feed line (d) of a further hydraulic motor (7) driven by the first pump (P-) via a check valve (Vq). 309832 / 0U6 Emptied