DE10255738A1 - Double-circuit hydraulic system for controlling consumers of mobile equipment such as track equipment comprises two circuits interconnected by an interconnecting valve arrangement having two valve devices - Google Patents

Abstract

Double-circuit hydraulic system for controlling consumers of mobile equipment such as track equipment comprises two circuits (2, 4) interconnected by an interconnecting valve arrangement (38) having two valve devices. Each valve device is assigned to one of the circuits and controls the connection to the other circuit as a function of load pressure and pump pressure. The connection of the line sections guiding the load pressure is designed so that the load pressure from the other circuit is not registered in the assigned circuit. Preferred Features: The interconnecting valve arrangement is housed in an intermediate plate (36) of a valve block.

Description

The invention relates to a hydraulic Dual circuit system for controlling consumers of a mobile device, in particular of a caterpillar device according to the preamble of claim 1.

In the US 6,170,261 B1 is a hydraulic. Two-circuit system of a mobile device, for example a chain or caterpillar device, is disclosed. In such caterpillar devices, the undercarriage has two chains, each of which can be controlled separately from one another via one of the hydraulic circuits. To the two hydraulic circuits of the chain device, a slewing gear and aggregates of the equipment, such as the boom, the dipper stick and the bucket are also connected. Each of the two hydraulic circuits is supplied with pressure medium by a variable displacement pump, which is controlled as a function of the highest load pressure of the consumers in the respective assigned circuit.

In the event that at least one consumer of the equipment is / should be operated in addition to the two chains, there is the possibility of interconnecting the two hydraulic circuits in order to avoid a supply of pressure medium. At the in the US 6,170,261 B1 disclosed solution, this interconnection of the two hydraulic circuits takes place via an interconnection valve, via which the pressure lines connected to the two pumps and the load pressure signaling lines of the two circuits are interconnected. The interconnection valve is controlled depending on the pressure medium supply to the additional consumer. In addition, the operator can intervene manually and interconnect the two circles.

The disadvantage of this solution is that, for example, when controlling a consumer connected to the hydraulic circuit with a high pressure medium requirement and low pressure and when controlling a consumer connected to the other circuit with a low quantity requirement and high pressure, both circuits are connected via the interconnection valve that the higher load pressure of the latter circle is also present in the first circle. Due to this higher load pressure, the pump of the first circuit is started up, so that both circuits are raised to the higher pressure level. The pressure in the first-mentioned hydraulic circuit must then be reduced accordingly to the required pressure level, which results in considerable energy losses. Another disadvantage is that the solution according to US 6,170,261 B1 A considerable amount of circuitry is required to tap the load pressure from the additional consumer and to control the interconnection valve.

In contrast, the invention is the Task to create a hydraulic dual-circuit system, which with a simple structure minimizes energy losses in the If the two circuits are interconnected.

This task is performed by a hydraulic two-circuit system solved with the features of claim 1.

According to the invention, the hydraulic two-circuit system an interconnection valve arrangement with two valve devices, which each prevent the interconnection of the two circles a higher load pressure acting in one of the circles with a low one Pressure medium requirement in the other circle with lower load pressure and high pressure medium requirements are reported. That is, in both circles the actual Load pressure corresponding to the requirements of the respective variable displacement pump reported, so in the case where in one of the circles a high If the pressure is low, the variable pump is not started up and thus the energy losses compared to solution mentioned at the beginning are significantly minimized. However, the solution according to the invention allows that in the In the case where there is high pressure in one of the circles with a high pressure medium requirement, this high load pressure is reported to the second circuit if there is a lower load pressure in this.

In a specific embodiment of the Invention, the interconnection valve arrangement has two pressure compensators, each of which is assigned to one of the circles. These pressure balances are each in the opening direction of the load pressure tapped in the respective circle and in the closing direction are acted upon by the respective pump pressure. Furthermore are Check valves in load pressure lines connected to the pressure compensators or the like provided that prevent when the pressure compensator is open, that a higher, from one connected circuit via the open pressure compensator into this assigned circle is reported. That is, the notification of this higher load pressure in the other circle is only possible if the circle with higher Pressure compensator assigned to load pressure opens.

The solution with two pressure compensators and two check valves is extremely simply constructed, whereby only the pump pressures and the load pressures must be tapped.

It becomes special with this variant preferred if the pressure compensators in addition to the load pressure in the opening direction or acted upon by the force of a spring, the spring force less than the pump Δp is.

In the case in which the valve arrangements for controlling the consumers and the chassis of the mobile device, for example the caterpillar device, are assembled in a control block in plate construction, it is preferred that the two pressure compensators and the associated rear impact valves are combined in an intermediate plate, so that the connection to the two circles is extremely simple.

With the solution described above the interconnection of the two circles automatically depending of the pressures applied to the pressure compensators (pump pressure, load pressure). In the case, that arbitrary an advantageous further training is to be intervened the invention proposed that on the effective in the opening direction of the control surface Pressure compensating control pressure - for example the load pressure - via a directional valve tap off. The output connection of this directional valve connects for example, in a basic position, the one loaded with the load pressure Spring chamber of the assigned pressure compensator with the tank, so that this Pressure compensator always remains in the closed position and thus an interconnection of the two circles over this pressure compensator is not possible is. In a further switching position of the directional valve can be on this Spring chamber the higher of the two pump pressures be created. The respective pressure compensator is always in this switch position open, and both circles over connected this pressure compensator. In the third switch position lies on Spring space the load pressure on - the Interconnection valve arrangement then works as described above Automatic mode.

The directional control valve is preferred as an electrically operated 4/3-way valve designed, that arbitrarily by the operator in one of the three operating positions described above is switchable (automatic operation, locking of the circles and Interconnect the circles).

The hydraulic dual-circuit system according to the invention let yourself particularly advantageous to use in a caterpillar device in which the hydraulic motors to drive the two chains over one of the circles can be controlled.

Other advantageous further training the invention are the subject of further dependent claims.

The following is a most preferred embodiment the invention with reference to schematic drawings. Show it:

1 an extract of a circuit diagram of a control block for controlling a caterpillar device; a detailed representation of the circuit diagram 2 and

3 a directional control valve for controlling pressure compensators according to the circuit diagram 2 ,

This excavator control 1 is a two-circuit system with two hydraulic circuits 2 . 4 constructed, which are each supplied with pressure medium via a variable displacement pump, not shown. The one with the in 1 Control provided excavator has a chassis with two chains, the drives of which over the two circles 2 . 4 can be supplied with pressure medium independently of one another. In addition to the traction drive, other excavator consumers, such as a slewing gear, a stick, a bucket or a boom, are controlled via the dual-circuit system.

According to the excavator control 1 Realizing control block is made in disc construction, the two variable pumps, not shown, being connected to pressure connections P ₁ and P ₂ at the control block. This also has a tank connection T and work connections A ₁ , B ₁ and A ₃ , B ₃ , to which the drive of the right or left chain is connected. The other consumers of the excavator, such as the drive of the slewing gear, the hydraulic cylinders for actuating the stick, the bucket or the boom are connected to further connections A ₂ , B ₂ and A ₄ , B ₄ etc. In the exemplary embodiment shown, it is assumed that the boom is connected to the connections A ₂ , B ₂ and the bucket to the connections A ₄ , B ₄ .

The control block shown also has two load pressure connections, hereinafter referred to as LS ₁ and LS ₂ , via which the in the respective circuit 2 . 4 acting load pressure is tapped and led to the flow control valve (not shown) of the variable displacement pump, which is thus controlled as a function of this highest load pressure.

The control of the aforementioned consumers takes place in each case via a proportionally adjustable directional valve 6 , each with a pressure compensator 8th is connected downstream. The directional valve 6 has a variable measuring orifice forming a speed part and a directional part, the measuring orifice of the pressure compensator 8th is upstream and the directional part downstream of the pressure compensator 8th is arranged. Any pressure compensator 8th is in the closing direction of the load pressure and in the opening direction of the pressure downstream of the metering orifice of the directional valve 6 applied. The pressure compensator piston adjusts itself to a control position depending on the control pressures present, in which the pressure drop across the orifice of the proportionally adjustable directional control valve 6 is kept constant, so that a load pressure-independent volume flow control is made possible. Such LS controls are well known, so that a detailed description of the structure of the directional valve 6 and the downstream pressure compensator 8th can be dispensed with. The control of the directional valve 6 takes place via pilot valves 10 . 12 , via which a control pressure to the front control surfaces of a slide of the directional valve 6 is created. These pilot valves are actuated, for example, depending on the actuating movement of a joystick.

The directional valve connections 6 are via a pressure line 14 . 16 connected to the pressure port P ₁ or P ₂ . Furthermore, each directional valve has two working connections, each via a working line 18 respectively. 20 are connected to the assigned consumer connections A, B. An outlet connection of the directional valve is used to return the pressure medium from the consumer 6 over a tank line 22 connected to the tank port T of the control block.

To limit the maximum pressure supplied to the consumer, pressure relief valves are also provided in the working lines, the pressure relief valves limiting the pressure at the working connections A ₂ , B ₂ , B ₁ and B ₃ and A ₄ (not shown) being designed with a suction function, so that if the consumer runs ahead, pressure medium can be sucked in from the tank to avoid cavity appearances. One each to the load pressure connection LS of the two circuits 2 . 4 connected load pressure reporting line 28 . 30 is via an LS flow control valve 32 respectively. 34 with the common tank line 22 connected.

The pressure balances 8th are designed in such a way that, in their fully open end position, the pressure at their inlet (pressure downstream of the orifice plate) is fed into the load pressure line 28 respectively. 30 report so that it always has the highest load pressure in the respective circuit 2 or 4 lies.

The directional valves described above with the assigned pressure compensator 8th , the pilot valves 10 . 12 as well as the pressure relief valves 24 . 25 can each be accommodated in a disc or in a common control block. To connect the two hydraulic circuits 2 . 4 is in a washer 36 an interconnect valve assembly 3 - 8th provided, via which the pressure lines in certain operating states 14 . 16 of the two hydraulic circuits 2 . 4 can be interconnected so that the controlled consumers are supplied with pressure medium by both variable pumps.

The structure of the interconnection valve arrangement is shown on the basis of the enlarged illustration 2 explained.

The interconnect valve assembly 38 has two pressure compensators 40 . 42 each with a spring 44 are biased towards their open position. The spring force of the spring is designed so that it is slightly below the pump Δp. If this is, for example, about 20 bar, the spring force of the spring 44 are between 10 and 19 bar.

In the 2 upper pressure compensator 40 is the circle 2 and the lower pressure compensator 42 the circle 4 assigned. The one on the pressure line 14 The applied pressure (pump pressure) becomes a control surface of the pressure compensator that is effective in the closing direction 40 out and in the load pressure line 28 of the circle 2 applied maximum load pressure via a control line 46 tapped and to an effective control surface of the pressure compensator in the opening direction 40 guided. In the illustrated embodiment, the control line opens 46 in the spring space for the spring 44 on.

The pressure in the pressure line is correspondingly 16 of the second circle 4 to an effective control surface of the pressure compensator in the closing direction 42 and the pressure in the load pressure reporting line 30 via another control line 48 in the spring chamber of the pressure compensator 42 guided.

The two input connections P and LS of the pressure compensators 40 . 42 are with the assigned pressure lines 14 respectively. 16 and the load pressure reporting lines 28 respectively. 30 connected. Upstream of the LS connection of the pressure compensators 40 . 42 is a check valve each 50 . 52 provided that a pressure medium flow from the load pressure signaling line 14 respectively. 16 to the assigned LS connection, but blocked in the opposite direction.

The two output connections A, B are with the load pressure signaling lines 28 . 30 or the pressure lines 14 . 16 of the other circle 2 . 4 connected.

The function of this interconnection valve arrangement is based on two operating states the excavator control explained.

It is initially assumed that there is an operating state in which the consumer connected to the working connections A ₂ , B ₂ , for example the handle, requires a large amount of pressure medium and accordingly a comparatively low pump pressure in the hydraulic circuit 2 is applied. The to the work connections A ₄ , B _{4 of} the second circle 4 connected consumers, for example the boom, on the other hand, should only require a small amount of pressure medium at a comparatively high pump pressure. In this operating state, the second circuit 4 Δpp assigned pressure compensator 42 held in its closed position by the high pump pressure while the first circuit 2 assigned pressure compensator 40 due to the drop in pump pressure is brought into a control position in which the connections P, LS are connected to the connections A, B. This allows the second circle 4 assigned variable pump pressure medium to the to the first circuit 2 Promote connected stem (connections A ₂ , B ₂ ) so that the higher pressure medium requirement of this consumer is secured. The check valve 50 prevents the higher one in the load pressure signaling line 30 applied load pressure in the load pressure signaling line 28 of the first circle 2 is reported so that the pressure level in this circuit remains low and the energy losses described above do not occur. The pressure compensator throttles in its control position 50 the pressure medium flow from the higher, in the second circle 4 prevailing pressure level to that in the first circle 2 required pressure level.

It is now assumed that the crawler device is traveling straight and both chains are supplied with the full amount of pressure medium. Both variable pumps are fully raised and the pressure compensators are pressurized with the maximum pump pressure in the closing direction and are therefore closed and both circuits 2 . 4 separated from each other. Now is another consumption cher, for example the boom (connections A ₂ , B ₂ ) switched on, the pressure in the first circuit drops due to the pressure medium requirement of this consumer 2 from. Without interconnect valve arrangement 38 the left chain (connection A ₁ , B ₁ ) would then not be adequately supplied with pressure medium, so that the crawler device turns. This is through the interconnection device 30 but prevented in the following way.

Due to the pressure drop in the first circle 2 and the corresponding lowering of the pump pressure becomes the pressure compensator 40 brought into their regular position so that the two circles 2 . 4 are interconnected. By connecting these two circuits, the pump pressure in the second circuit also drops 4 from, so that the pressure compensator assigned to this circuit accordingly 42 opens so the two circles 2 . 4 over both pressure balances 40 . 42 are interconnected. In other words, a kind of LUDV single-circuit system is set up, which is operated in undersaturation - the crawler device remains in a straight line and the connected consumer (boom) is supplied with pressure medium.

In the embodiment described above, the interconnection valve arrangement operates 38 automatically and binds the two circles 2 . 4 in the event of one or both circles becoming under-saturated. It may now be necessary for the operator to arbitrarily interconnect both circuits in order, for example, to ensure optimal supply to one of the consumers. However, it may also be necessary to lock the two circles against each other in order to prevent interconnection.

These variants can be implemented in a comparatively simple manner by the two control lines 46 . 48 not directly to the control surface of the pressure compensators acting in the opening direction 40 . 42 (Spring chamber) are guided but each via a control valve 54 as it is in 3 is shown.

This in 3 shown control valve 54 is designed as a 4/3-way valve and has a pressure port P, a LS port LS and a tank port T and a control port S with the control line leading to the spring chamber 46 respectively. 48 connected is. The LS connection is to the load pressure signaling line 28 respectively. 30 of the respective circle 2 . 4 connected. The pressure port P is via a shuttle valve 56 with the two pressure lines 14 . 16 of the two hydraulic circuits 2 . 4 connectable. Via the shuttle valve 56 the higher of the two pump pressures is always led to the pressure port P. In the basic position shown ( 0 ) of the control valve 54 the pressure port P and LS port LS are shut off, and the control line 46 ( 48 ) connected to the tank connection T. In other words, the tank pressure acts in the spring chamber, so that the respective pressure compensator 40 . 42 is biased in the closed position by the respective acting pump pressure - the two pressure compensators 40 . 44 are closed and the two circles 2 . 4 locked against each other.

When switching the electrically operated control valve 54 in switch position (a) is in the respective circle 2 . 4 applied load pressure in the control line 46 ( 48 ) switched through - the interconnection valve arrangement 38 works in the same way as it does with the 1 and 2 was explained.

When switching the control valve 54 In the position marked with (b), the pressure port P is connected to the control port S, so that the higher of the two pump pressures and the associated pressure compensator are effective in the spring chamber 40 ( 42 ) by the force of the spring 44 is held in the open position. In other words, the system is then operated as a single-circuit system in which the consumers are supplied with pressure medium by both pumps.

A hydraulic dual-circuit brake system is disclosed to control consumers of a mobile device, for example of a caterpillar device. The two hydraulic circuits can be connected via an interconnection valve can be interconnected, with a device, for example Check valves, it is ensured that when the circles are interconnected a higher one No load pressure with low pressure medium requirement in one of the circles is reported in the other circuit with lower load pressure. at The interconnection valve arrangement has a preferred variant two pressure compensators, each of the pump pressure and the load pressure in the assigned circuit and which check valves are upstream.

1

excavator control

2

first circle

4

second circle

6

way valve

8th

pressure compensator

10

pilot valve

12

pilot valve

14

pressure line

16

pressure line

18

performance

20

performance

22

tank line

24

Pressure relief valves

26

Pressure relief valves

28

Load pressure signaling line

30

Load pressure signaling line

32

LS flow control valve

34

LS flow control valve

36

washer

38

Interconnecting valve arrangement

40

pressure compensator

42

pressure compensator

44

feather

46

control line

48

control line

50

check valve

52

check valve

54

control valve

56

shuttle valve

Claims (8)

Hydraulic two-circuit system for controlling consumers of a mobile device, in particular a caterpillar device, with each hydraulic circuit ( 2 . 4 ) a variable displacement pump is assigned, via which the assigned consumers can be supplied with pressure medium, and the two circuits ( 2 . 4 ) via an interconnection valve arrangement ( 38 ) can be connected to each other in such a way that the variable displacement pump of one circuit ( 2 . 4 ) Pressure medium in the other circle ( 4 . 2 ) so that this circle ( 4 . 2 ) can be supplied with pressure medium via both variable displacement pumps, and the variable displacement pumps depending on the load pressure in the assigned circuit ( 2 . 4 ) are controlled, characterized in that the interconnection valve arrangement ( 38 ) two valve devices ( 40 . 42 ; 50 . 52 ), each one of the circles ( 2 . 4 ) is assigned and via which, depending on the load pressure and the pump pressure in the assigned circuit ( 2 . 4 ) the connection to the other circle ( 4 . 2 ) can be controlled, the connection of the line sections carrying the load pressure being designed such that the load pressure from the other circuit ( 4 . 2 ) not in the assigned circle ( 2 . 4 } can be reported. Dual circuit system according to claim 1, wherein the interconnection valve arrangement ( 38 ) two pressure compensators ( 40 . 42 ) has a pressure compensator ( 40 ) from one of the circles ( 2 ) acting pump pressure in the closing direction and the load pressure in the opening direction and the other pressure compensator ( 42 ) corresponding to the pump pressure and the load pressure in the other circuit ( 4 ) is acted upon, and via the pressure and LS lines ( 14 . 16 ; 28 . 30 ) of the two circles ( 2 . 4 ) can be connected, whereby in the LS lines ( 28 . 30 ) Check valves ( 50 . 52 ) are provided which control oil flow from the circuit ( 2 . 4 ) with the higher load pressure in the circuit ( 4 . 2 ) with the lower load pressure. Dual circuit system according to claim 1 or 2, wherein the pressure compensators ( 40 . 42 ) one spring each acting in the opening direction ( 44 ) whose spring force is less than the pressure drop across the pump. Dual circuit system according to one of the preceding claims, wherein the interconnection valve arrangement ( 38 ) in an intermediate plate ( 36 ) of a valve block. Dual circuit system according to one of the preceding claims, with a locking device ( 54 ) for locking the interconnection valve arrangement, so that either a two or single circuit system can be set. Dual circuit system according to claims 2 and 6, wherein the locking device is in each case a pressure compensator ( 40 . 42 ) assigned control valve ( 54 ) through which a spring chamber of the pressure compensator ( 40 . 42 ) optionally with the load pressure in the associated circuit ( 2 . 4 ), with the tank pressure or with the higher of the pump pressures. Dual circuit system according to claim ( 6 ), the control valve ( 54 ) is an electrically operated 4/3-way valve. Dual circuit system according to one of the preceding claims, wherein the consumer chassis drives for two chains of a caterpillar device as well further equipment units of the crawler device such as spoons, Stick, boom and a slewing gear are.