EP1190178B1 - Switching device for a machine - Google Patents

Abstract

A switching device for a machine, especially a digger, has at least one supply connection and one useful connection in addition to at least one hydraulic accumulator. An on-off valve is arranged between the supply connection and the useful connection, and separates the supply connection at least partially from the useful connection in one of its switching positions, in addition to ensuring that the hydraulic accumulator is charged on the fluid side via the supply connection. In another switching position, the supply connection is connected to the useful connection. A substantial improvement relative to conventional switching devices is attained by being able to guarantee an emergency function before the machine is used to perform work.

Description

The invention relates to a switching device for a work machine with the features of the preamble of claim 1.

Related switching devices for working machines are in a variety of embodiments in the market freely available. The supply connection serves to connect a pump unit, for example in the form of a hydraulic pump to the hydraulic working group, the connected to the service port, with pressurized hydraulic oil to supply. The pertinent hydraulic circuits are in usually divided into a high pressure part and a low pressure part, wherein at the low pressure part, the actuating device for the working machine is connected, via an operator, such as the Excavator guide, the equipment of the high pressure circuit accordingly for working processes. The addressed hydraulic accumulator is used then, in the event of a supply failure within the hydraulic circuit to ensure the hydraulic supply for a certain period of time to avoid that the work equipment, for example in the form of a Excavator bucket, can fall down in the raised state or the like, which would pose a security risk.

In the known switching devices, it is now so that for the manufacture This safety function of the hydraulic accumulator must first be loaded, the later ensures the emergency supply, so that in known machines they can not start working immediately, but rather must first a defined actuation function by the excavator operator be executed, for example, by lifting the bucket to order Make sure that the memory in this process for the later emergency function loaded. In general, the pending operation is in described in the manual of the machine and must accordingly be done exactly.

From DE-A-30 34 467 a generic switching device for a work machine known to monitor a connection between a supply connection and a storage tank (tank T) on one side and a hydraulic accumulator on the other side, with a pilot valve whose valve member from the pressure in the hydraulic accumulator can be acted upon and with a controllable from the pilot valve switching valve, wherein the valve member of the pilot valve to the switching valve leading control line either to the supply terminal or the Reservoir (tank T) connects. With the known switching device is a safe switching on and off of the hydraulic accumulator allows. The valve member of the pilot valve does not assume a control position, i. the connection between the hydraulic pump and the hydraulic accumulator is either completely open or completely closed. The valve member performs Umsteuem from pump to accumulator pressure and vice versa a rapid switching movement and thus acts as a bistable flip-flop. This will a safe switching on and off of the hydraulic pump or the reservoir (Tank T) or the respective consumer. The realization of a Emergency supply in the sense outlined above is with this known switching device However, not possible, which ensures only a monitoring function.

Based on this prior art, the invention is therefore the Task on, the known switching devices continue to do so to improve that it is possible with them, even then an emergency function ensure before starting to work with the work machine becomes. A pertinent task solves a Schaltüngsvorrichtung with the Features of claim 1.

Characterized in that according to the characterizing part of claim 1 for the Switching the switching valve of the pending in the secondary line switching pressure essentially corresponds to the fluid-side accumulator pressure and that zwisehen arranged the supply connection of the switching valve and the secondary line, a pressure reducing valve is that within a hydraulic circuit a low pressure part separated by a high pressure part, both via the supply connection are supplied, is the high pressure circuit when switching the machine from the supply connection and thus from the supply circuit disconnected and with switching on the working machine is the hydraulic accumulator charged over the supply connection before working with the Work machine is started. Thus, immediately after switching on of the drive unit and thus the hydraulic pump the emergency supply to Available and the operator can immediately start working, without first having to think about the emergency function. This serves the Security and facilitates the operation of the machine and provides their immediate work assignment for sure. The separation of the supply connection From Nutzanschluß can completely in the sense of fluid shut-off be. Preferably, however, only a partial separation is provided, for example, by means of a throttle, the still such a partial supply of the high-pressure circuit for certain work functions, while the emergency care is guaranteed.

Furthermore, both the supply can be connected via only one supply connection the high-pressure part and the low-pressure part are ensured and in contrast to an optionally electrical control via a Electric solenoid for the switching valve is the operation of the same pressure-controlled and thus functionally reliable.

In a further preferred embodiment of the invention Switching device is between the secondary line and the hydraulic accumulator arranged in the direction of the hydraulic accumulator check valve, about the safe separation in case of power failure, in particular the Pump current, from low pressure part to high pressure part is ensured. Preferably, the hydraulic accumulator is with its fluid side to the low pressure part connected, via another valve, in particular a Slide valve, the control unit in particular provided with a joystick provided. The control unit as part of the operating device of the working machine is thus supplied via the fluid side of the hydraulic accumulator and can via appropriate control units, the low pressure part with the affect him connected work equipment.

In a further preferred embodiment of the invention Switching device opens the secondary line in another Nutzanschluß and on the low pressure side there is a third usable connection, the via a third valve, in particular in the form of another slide valve, can be locked. In this way, stand within the Switching device even more useful connections for Ansteuervorgänge the working machine available. In this case, preferably the slide valves as well as the pressure relief valves and the pressure reducing valve connected to a tank connection, which is substantially ambient pressure having.

In a particularly preferred embodiment of the invention Switching device, the hydraulic accumulator is a diaphragm accumulator, wherein the Hydraulic accumulator and all valves as screw-in parts, in particular in shape of Einschraubpatronen, are formed. Preferably, the Switching device formed in a block design, wherein the switching device block Outside peripheral side with the supply connection, the Nutzanschlüssen and the tank connection is provided as well as with connection points for receiving the screwed parts. Preferably, run in the Inside the switching device block between the connecting lines the connections and the connection points. In this way is one modular construction of the switching device concept realized, the compact constructive little space required within the machine. Furthermore, in case of failure of a component this is easy and inexpensive exchangeable for a spare part. The switching valve 12 and the Check valve RV are preferably designed as kits.

Preferably, the low pressure part has at least one working pressure of 20 bar and the high pressure part a working pressure of at least 200 bar.

In the following, the inventive switching device is based on a Embodiment-explained in more detail after the drawing.

Fig.1

einen hydraulischen Schaltplan betreffend die Schaltvorrichtung;

Fig.2

in der Art einer Explosionszeichnung die Schaltvorrichtung nach der Fig.1.

It shows in principle and not to scale representation of the

Fig.1

a hydraulic circuit diagram relating to the switching device;

Fig.2

in the manner of an exploded view, the switching device according to Fig.1.

The switching device according to the drawing is for a working machine, in particular for an excavator, provided and has a supply connection P and a user port P 'on. Furthermore, as a membrane memory trained hydraulic accumulator 10 available. Like the rest 1 shows is between the supply terminal P and the Nutzanschluß P 'serving as a switching valve switching valve 12 is arranged, the in the switching position shown in FIG. 1 the supply connection P from the service port P 'separates or throttles and the fluid-side charge the hydraulic accumulator 10 is ensured via the supply terminal P. The Gas side of the hydraulic accumulator 10 is connected to a working gas, in particular in Form of nitrogen, provided with a predeterminable pressure. In the other Switching position of the switching valve 12 would then be the supply terminal P. connected to the Nutzanschluß P 'fluid leading.

In its initial position shown in Figure 1 separates at least partially the switching valve 12 the supply port P from the user port P ' and for switching the switching valve 12 into its supply port P with the user port P 'connecting supply position is used in a secondary line 14 pending switching pressure, which is essentially the Fluid side accumulator pressure of the hydraulic accumulator 10 corresponds.

Between the mentioned switching valve 12 and the secondary line 14 is a pressure reducing valve DM arranged inside the hydraulic Working cycle a low pressure part 16 of a high pressure part 18th disconnects, both of which are powered by the supply terminal P. Between the secondary line 14 and the hydraulic accumulator 10 is in the direction of Hydraulic accumulator 10 opening check valve RV arranged. Furthermore is the hydraulic accumulator 10 with its fluid side to the low pressure part 16 connected, via another valve 20, in particular in the form a slide valve, a control unit not shown for actuating the work equipment, in particular with a joystick (not shown) provided for operation by an operator supplied. The pertinent connection is designated in Figure 1 with Azg.

In the secondary line 14 opens another useful connection branch, wherein on the low pressure side 16 a third useful terminal Ap is present, the via a third valve 22, in particular in the form of a further slide valve, can be locked. The two slide valves 20 and 22 are spring loaded held in their basic position shown in Figure 1 and are electrically via solenoids WK1, WK2 can be actuated. Thanks to the other two Useful connections Ap and branch can be further on the low pressure side Units of the work machine hydraulically connect to the switching device. Furthermore, the high pressure part 18 via a pressure relief valve DB3 and the low pressure part 16 via a pressure relief valve DB4 secured. The two slide valves 20,22 and the two Pressure relief valves DB3 and DB4 and the pressure reducing valve DM are to a tank connection T, which has substantially ambient pressure, connected to the fluid.

2, the hydraulic accumulator 10 is a diaphragm accumulator formed, wherein the hydraulic accumulator 10 and all valves 12,20,22, DM, RV, DB3 and DB4 as screw-in parts, in particular in the form of Einschraubpatronen, are formed. As further shown in Fig.2, the switching device is formed in block construction, wherein the Schaltvornchtungsblock 24 is formed in the manner of a cube or cuboid and the outer peripheral side of the supply terminal P, the Nutzanschlüsse P ', branch and Ap and the tank connection T. Furthermore, he has the terminal Azg on and corresponding connection points 26 for recording the screwed. Inside the switching device block 24 (not shown in detail) then make appropriate connection lines the connections between the addressed ports and the Connection points 26 ago.

To clarify the switching device described this is based on their function explained in more detail. With switching on the working machine, in particular in the form of an excavator, the drive unit runs, in particular Shape of a diesel engine, and drives a hydraulic pump (not shown) at. The hydraulic pump then delivers to the supply port P a Fluid working pressure, for example, at the rate of 230 bar. When starting the Working machine is the switching valve 12 in its in Fig.1 shown locked or throttled switching position and the fluid pressure of the high pressure part 18 is on the pressure reducing valve DM on the Working pressure of the low-pressure part 16 brought, for example by the Pressure reducing valve is set to a setting pressure of 45 bar. The Return valve RV is opened against its spring force and the supply connection P supplies the hydraulic accumulator 10 with reduced pressure on its fluid side.

The memory is now fluid side against the gas working pressure as long filled or charged until the pressure in the secondary line 14 is approximately the desired working pressure in the hydraulic accumulator 10, ie, for example 35 bar with a delivery volume of 6.6 l / min. Is in the low pressure part 16 a pressure equilibrium established between the fluid side of Hydraulic accumulator 10 and the upcoming pressure in the secondary line 14, wherein the closing force of the return spring of the check valve RV to include is, the switching valve 12 is in its fluid-conducting switching position brought and the supply terminal P with the user port P ' connected, so that then on the working equipment of the working machine, For example, in the form of hydraulic cylinders, the working pressure of High pressure part 18 of the switching device can be pending. Will the slide valves 20,22 connected via the electromagnet WK2 or WK1, is the pressure in the low-pressure part 16 at the terminals Azg and Ap, which are otherwise connected fluid leading to the tank side T out. About the Connections Azg and Ap can then be the one for the control unit for Supply working machine with low pressure or another hydraulic consumer the entire hydraulic circuit (not shown).

If it now comes to malfunctions, is an emergency function on the hydraulic accumulator 10 ensured, then over the check valve RV opposite the high pressure part 18 shut off an emergency supply via the respective connection Azg and / or Ap ensures. In this way can be, for example, a raised bucket in case of failure of the Keep the hydraulic supply in position or lower it in a defined way. One Another useful connection for another hydraulic consumer on the Low pressure side is given over the Nutzanschluß branch. With the invention Switching device is thus ensured that before the actual Start of work with the working machine of the emergency storage in the form of Hydraulic accumulator 10 is filled with a fluid reservoir under pressure, which then later can ensure an emergency supply in any case.

For a partial separation of the fluid supply for the high pressure circuit may be provided a throttle DR, so that the switching valve 12, such as 1, through a switching valve with throttle, as shown, can be replaced. In this way, the emergency care can be over ensure the hydraulic accumulator 10 and at the same time can be at least achieve a work function within the high pressure circuit.

Claims (8)

1. Switching means for a working machine, especially an excavator, with at least one supply and one utility connection (P, P'), and with at least one hydro store (10), whereby a switching valve (12) is located between the supply connection (P) and the utility connection (P'), which at least partly separates the supply connection (P) from the utility connection (P') in one of its switch positions and guarantees the fluid side charging of the hydro store (10) via the supply connection (P), whereby the supply connection (P) is connected with the utility connection (P') in another switch position, whereby the switching valve (12) in its starting position at least partially separates the supply connection (P) from the utility connection (P'), and serves for the switching of the switching valve (12) into its supply position connecting the supply connection (P) with the utility connection (P'), for a switching pressure supplied by an auxiliary line (14), characterised in that the switching pressure supplied by the auxiliary line (14) for the switching of the switching valve (12) is substantially equal to the fluid side store pressure, and in that a pressure reducing valve (DM) is located between the supply connection of the switching valve (12) and the auxiliary line (14), which separates a low pressure section (16) from a high pressure section (18) within a hydraulic circuit, both of which are supplied via the supply connection (P).
2. Switching means according to Claim 1, characterised in that a non-return valve (RV) opening in the direction of the hydro store (10) is located between the auxiliary line (14) and the hydro store (10).
3. Switching means according to Claim 2, characterised in that the hydro store (10) is connected with the low pressure section (16) with its fluid side, which supplies the control unit, especially with a joystick, via a further valve (20), especially a displacement valve.
4. Switching means according to one of the Claims 1 to 3, characterised in that auxiliary line (14) opens into a further utility connection (Ast), and in that a third utility connection (Ap) is provided on the low pressure side (16), which can be turned off via a third valve (22), especially in form of a further displacement valve.
5. Switching means according to Claim 4, characterised in that the high pressure section (18) and the low pressure section (16) are secured by means of pressure limiting valves (DB3, i.e. DB4).
6. Switching means according to Claim 5, characterised in that the displacement valves (20, 22) as well as the pressure limiting valves (DB3 and DB4) and the pressure reducing valve (DM) are connected with a tank connection (T).
7. Switching means according to Claim 6, characterised in that the hydro store (10) consists of a membrane store, and in that the hydro store (10) as well as all valves (12, 20, 22, RV, DM, DB3 and DB4) consist of threadable components, especially in the form of threadable cartridges.
8. Switching means according to Claim 7, characterised in that the same is designed as a block construction, in that the switching means block (24) is equipped with the supply connection (P), the utility connections (P', Azg, Ap, Ast), and the tank connection (T) around its outer circumference, as well as with connection points (26) for receiving the threaded components, and in that the connection lines between the utility connections and the connection points (26) extend inside the switching means block (24).

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