DE60108695T2 - Hydraulic circuit for construction machinery - Google Patents

Description

TECHNICAL AREA

The The present invention relates to a hydraulic circuit, installed in a construction machine and a pressure balance flow divider valve includes.

BACKGROUND OF THE INVENTION

Like in the 3 In Japanese Patent Provisional Publication No. 2000-73409, there is disclosed a hydraulic circuit of a construction machine provided with a pressure compensating flow divider valve 8th which is located between a group of components to which a first pump 2 and a second pump 3 which are designed to be mounted on a hydraulic excavator-mounted engine 1 driven as well as another group of components to which a left-hand movement circle 5 , a legal circle 6 and an independent attachment circuit 7 belong is located.

The left movement circle 5 includes a left-hand control spool 11a a main control valve 11 which is designed to be that of the first pump 2 coming hydraulic fluid flow regulates. The legal circle 6 includes a right-hand control spool 12a a main control valve 12 which is designed to be that of the second pump 3 coming hydraulic fluid flow regulates. The thus regulated hydraulic fluid drives the hydraulic motors (not shown) of the left and right chain belt drive systems mounted on the hydraulic excavator.

The above-mentioned independent attachment circuit 7 includes an attachment control valve (not shown) for controlling the first pump 2 and the second pump 3 coming hydraulic fluid. With the aid of the hydraulic fluid controlled by the attachment control valve, the independent attachment circuit actuates an attachment such as a hydraulic breaker mounted at the front end of the excavator front work unit instead of the bucket.

If the drive of the hydraulic excavator and the actuation of its attachment run simultaneously, this is done by the pressure compensation flow divider valve 8th a compensation of the pressure of the first pump 2 discharged hydraulic fluid. This fluid is split so that it enters the left motion circle 5 and in the independent cultivation circuit 7 flows. In addition, the pressure compensating flow divider valve is similar 8th the pressure of the second pump 3 discharged hydraulic fluid, which is divided so that it is in the right motion circle 6 and in the independent cultivation circuit 7 flows. For this purpose, the pressure compensating flow divider valve 8th with a flow divider gate valve 13 , a pressure compensation valve 14 for the constant maintenance of the differential pressure between a port B1 and a port A1 of the flow dividing spool valve 13 (PB1 - PA1) at a certain level, a pressure balance valve 15 for the constant maintenance of the differential pressure between a port B2 and a port A2 of the flow pitch control valve 13 (PB2 - PA2) at a certain level as well as check valves 16 . 17 equipped, which are mounted in the output circuits, which of the two pressure compensation valves 14 . 15 to the independent attachment circuit 7 run.

The flow divider gate valve 13 is with internal oil channels 21 . 22 equipped whose opening characteristics are designed so that the flow rate of the first pump 2 promoted and to the left movement circle 5 branched hydraulic fluid is identical to the flow rate of that hydraulic fluid, the same time from the second pump 3 promoted and to the legal circle 6 is branched off. The flow divider gate valve 13 is moreover with internal oil channels 23 . 24 equipped whose opening characteristics are designed so that the flow rate of the first pump 2 subsidized and to the independent cultivation circuit 7 branched hydraulic fluid is identical to the flow rate of that hydraulic fluid, the same time from the second pump 3 promoted and to the independent cultivation circuit 7 is branched off.

In the configuration described above, when driving the hydraulic excavator and operating its attachment at the same time, the pressure compensating flow divider valve may 8th same flow rates hydraulic fluid to the left motion circle 5 and to the legal circle 6 regardless of the position of the flow divider gate valve 13 so that the excavator can maintain its straight ahead.

Generally speaking, each hydraulic pump installed in such a hydraulic excavator as described above has a threshold curve determined by the pump output and the discharge pressure determined by the engine output. A graph with such a threshold curve (hereinafter referred to as PQ diagram) is shown in FIG 2 shown. In other words, the hydraulic pump is designed so that the higher the relief pressure, the lower the pump capacity.

According to the structure of the above be written and in the 3 represented conventional, independent cultivation circuit 7 the pressure compensating valves work 14 . 15 so that the hydraulic fluid in a flow rate to the independent attachment circuit 7 is transported, the opening degree of the internal oil passages 23 . 24 of the flow divider gate valve 13 corresponds, regardless of the pressure in the circuit. As a result, almost all of the amount of hydraulic fluid delivered by the pump flows into the independent attachment circuit 7 when the flow rate of the pump, as in the PQ curve of 2 is reduced, because the pressure in the attachment circuit has reached a level sufficient to be almost identical to the relief pressure, if the internal oil passages 23 . 24 of the flow divider gate valve 13 open wide. As a result, no further hydraulic fluid flows into the actuators on the main body of the machine, such as the actuators of the hydraulic traction motors, etc.

consequently becomes in the moment, in the course of the operation of the attachment in cooperation with the main assembly actuators, for example the hydraulic traction motors, the pressure in the independent mounted circuit the relief pressure approaches, the movement of the main body actuators extremely slow.

to solution The above problem is an object of the present invention in presenting the hydraulic circuit of a construction machine, the one Pressure compensation flow dividing valve includes and supplying the main assembly actuators with a required Ensures hydraulic fluid, even if during the simultaneous actuation the actuators of the attachment and the main body of pressure in Mounting circuit approaches the relief pressure, causing a drastic reduction the speed of Hauptaufbauaktuatoren is avoided.

DISCLOSURE OF THE INVENTION

The The invention claimed in claim 1 relates to a hydraulic circuit a construction machine comprising: main circuits for controlling one from a tank by means of pumps arranged on the construction machine up pumped hydraulic fluid, causing the hydraulic fluid on the construction machine is supplied to arranged main assembly actuators; an attachment circuit for controlling pumped up from the tank by means of the pumps Hydraulic fluid, whereby the hydraulic fluid on the construction machine supplied mounted attachment becomes; a pressure compensating flow divider valve, which is designed to control the pressure of the hydraulic fluid supplied by the pumps compensates and splits, leaving the fluid in the main circuits and the attachment circuit flows; an external channel for returning the from the pressure balance flow divider valve supplied to the attachment circuit Hydraulic fluids in the tank; and a selector valve that looks so designed is that it from a Kanalverschließenden position in a the Channel opening Position can be switched when the pressure in the mounting circuit in the course simultaneous actuation the actuators of the attachment and the main body raised to a level which is almost equal to the relief pressure.

If In the configuration described above, the pressure in the attachment circuit during the simultaneous operation of the actuators of the attachment and the main body approaches the relief pressure, flows from the pressure balance flow divider valve to the external channels branched priority hydraulic fluid through the selector valve into the tank and increases the flow rate of the pump so that the main assembly actuators a larger amount of hydraulic fluid is supplied. Consequently, the problem does not occur in the implementation of the invention more on that action of the main bodybuilders at the moment becomes extremely slow, during which during simultaneous operation the actuators of the attachment and the main body of pressure in Attachment circuit approximates the relief pressure.

The claimed in claim 2 invention relates to a hydraulic circuit according to claim 1, wherein to the pumps a first pump and a second Pump belongs; the main circuits include a first main circuit which a left-hand control spool for controlling a left-hand hydraulic motor contains the machine structure, and a second main circuit including a rightward movement spool for Controlling a right-hand hydraulic motor; and wherein the pressure compensating flow divider valve a single flow dividing gate valve contains which is designed to control the hydraulic fluid so that it from the first pump the first main circuit and the second Pump the second main circuit in the same flow rate supplied becomes.

In the above-described configuration, when driving movement of the hydraulic shovel and operation of its attachment are concurrently performed, the pressure compensating flow divider valve ensures that the hydraulic fluid is constantly supplied to the first main circuit and the second main circuit at the same flow rate. Since the flow rate of the hydraulic fluid delivered from the left-hand motion spool of the first main circuit to the left-hand motion motor always coincides with the flow rate of the right-hand spool of the second main gear circle is conveyed to the right motion motor hydraulic fluid is identical, can be prevented with the invention, a deviation of the construction machine from driving straight ahead.

SHORT DESCRIPTION THE DRAWINGS

1 Fig. 12 is a circuit diagram of the hydraulic circuit of a construction machine according to an embodiment of the present invention.

2 FIG. 4 is a PQ diagram showing the characteristics of the pumps representing the relationship between the discharge pressure of the pump and the delivery rate.

3 is a circuit diagram of a conventional hydraulic circuit of a construction machine.

PREFERRED Embodiment THE INVENTION

The following is with reference to the 1 and 2 an embodiment of the present invention is explained.

1 shows an example of a hydraulic circuit, wherein a pressure compensating flow divider valve 38 located between a group of components to which a first pump 32 and a second pump 33 which are designed to be mounted on a construction machine, that is in the case of the present invention on a hydraulic excavator engine 31 be driven, as well as a group of components, including a first main circuit 35 , a second main circuit 36 and an independent attachment circuit 37 which is independent of these main circuits. The first pump 32 and the second pump 33 serve to through the pressure compensating flow divider valve 38 that from a tank 39 pumped hydraulic fluid to the first main circuit 35 , to the second main circuit 36 and to the independent attachment circuit 37 to pump.

The first main circuit 35 includes a main regulator valve 41 for controlling the amount of hydraulic fluid supplied by the first pump 32 is fed while the second main circuit 36 a main control valve 42 to regulate the amount of hydraulic fluid that is supplied by the second pump 33 is supplied.

The main control valves 41 . 42 serve to supply the main assembly actuators with that hydraulic fluid coming from the pumps 32 . 33 through the pressure balance flow divider valve 38 to the main control valves 41 . 42 while controlling the directions and flow rates of the hydraulic fluids.

The Hauptaufbauaktuatoren consist of hydraulic motors, which on the undercarriage are mounted, that is, from the left chain driving left hydraulic motor and the right-hand drive hydraulic motor for driving the right chain, a hydraulic swivel motor for moving the upper carriage on the undercarriage, and actuators for driving the boom, the dipper stick and the spoon at the front working unit of the superstructure, that is, one Dipper hydraulic cylinders, a boom hydraulic cylinder and a bucket hydraulic cylinder.

The main control valve 41 of the first main circuit 35 includes a left-hand control spool for controlling the left-hand hydraulic motor, and the main control valve 42 of the second main circuit 36 includes a right-hand control spool for controlling the right-hand hydraulic motor.

In addition, either the main regulator valve 41 or the main regulator valve 42 equipped with swivel control slides for controlling the swing hydraulic motor, with boom controls for controlling the boom hydraulic cylinder (s), with dipper stick spindles for controlling the dipper stick hydraulic cylinder and with bucket spools for controlling the bucket hydraulic cylinder.

The above-mentioned attachment circuit 37 includes an attachment control valve (not shown) for controlling hydraulic fluid delivery from the first pump 32 and the second pump 33 , The independent hydraulic circuit actuated by the hydraulic fluid regulated by the slider of the mounting control valve 37 an attachment, for example a hydraulic breaker, which is mounted at the front end of the front working unit of the hydraulic excavator instead of the bucket.

If the drive of the hydraulic excavator and the actuation of its attachment run simultaneously, this is done by the pressure compensation flow divider valve 38 a compensation of the pressure of the first pump 32 discharged hydraulic fluid. This fluid is divided so that it is in the left-hand circle 35 and in the independent cultivation circuit 37 flows. In addition, the pressure compensating flow divider valve is similar 38 the pressure of the second pump 33 discharged hydraulic fluid, which is divided so that it in the second main circuit 36 and in the independent cultivation circuit 37 flows. For this purpose, the pressure compensating flow divider valve 38 with a flow divider gate valve 43 , a pressure compensation valve 44 for the constant maintenance of the differential pressure between a connection B1 and a port A1 of the flow divider gate valve 43 (PB1 - PA1) at a certain level, a pressure balance valve 45 for the constant maintenance of the differential pressure between a port B2 and a port A2 of the flow divider gate valve 43 (PB2 - PA2) at a certain level as well as check valves 46 . 47 equipped, which are mounted in the output circuits, which of the two pressure compensation valves 44 . 45 to the independent attachment circuit 37 run.

The above-mentioned, in the pressure balance flow divider valve 38 Integrated single flow divider gate valve 43 is with internal oil channels 51 . 52 equipped by the first pump 32 depart, as well as with internal oil channels 53 . 54 that from the second pump 33 depart. The internal oil channel 51 serves to transport the hydraulic fluid to the first main circuit 35 branches off, and the internal oil passage 52 serves to transport the hydraulic fluid, which is the independent attachment circuit 37 branches. The internal oil channel 53 serves to transport the hydraulic fluid to the second main circuit 36 branches off, and the internal oil passage 54 serves to transport the hydraulic fluid, which is the independent attachment circuit 37 branches.

The internal oil channels 51 . 53 of the flow divider gate valve 43 have such opening characteristics that the flow rate of the hydraulic fluid coming from the first pump 32 promoted and to the first main circuit 35 is identical to the flow rate of that hydraulic fluid that is simultaneously from the second pump 33 promoted and to the second main circuit 36 is branched off. Meanwhile, the internal oil channels point 52 . 54 such opening characteristics that the flow rate of the hydraulic fluid from the first pump 32 promoted and to the independent cultivation circuit 37 is identical to the flow rate of that hydraulic fluid that is simultaneously from the second pump 33 promoted and to the independent cultivation circuit 37 is branched off.

In other words, the flow divider gate valve 43 controls the hydraulic fluid so that the hydraulic fluid from the first pump 32 to the first main circuit 35 and to the attachment circuit 37 is transported, with the same flow rate as the hydraulic fluid from the second pump 33 to the second main circuit 36 and to the independent attachment circuit 37 is transported.

The internal oil channels 52 . 54 for transporting the hydraulic fluid to the independent attachment circuit 37 are each with variable throttles 55 . 56 equipped, the opening areas can be changed according to the adjustment of the slide.

The flow divider gate valve 43 is designed so that at its one end the constant force of a spring 57 and at its other end, from a port Pi via a pilot pressure introduction passage 58 introduced pilot pressure, so that the displacement of the spool valve at the equilibrium point between the thrust force of the pilot pressure and the restoring force of the spring 57 is regulated.

More specifically, the lower the pilot pressure at port Pi, the denser the flow divider gate valve 43 at the position 61 , However, it is also true that the higher the pilot pressure at port Pi, the more dense the flow divider gate valve shifts 43 about the position 62 to the position 63 , so that the variable chokes 55 . 56 continue to open. A drainage oil channel 64 gets out of the flow divider gate valve 43 brought out and communicates with a tank.

A pressure sensor 66 is located in an independent cultivation management 65 , through the hydraulic fluid to the independent attachment circuit 37 is transported. An external channel 67 branches off from a priority channel that extends between the pressure balance valve 45 and the check valve 47 in the pressure compensating flow divider valve 38 located.

An electromagnetic selector valve serving as a selector valve 68 is located in the external channel 67 so that this via the electromagnetic selector valve 68 with the tank 39 connected is.

At the electromagnetic selector valve 68 it is a selector valve that is designed to switch from the energized solenoid from a channel closing position to a channel opening position when the pressure in the independent attachment circuit 37 that is, the attachment circuit pressure increases to a level approximately identical to the relief pressure in simultaneously operating the actuators of the attachment and the main assembly.

In the configuration described above, that of the pressure compensating flow divider valve 38 to the independent attachment circuit 37 transported hydraulic fluid through the external channel 67 in the tank 39 be returned because the electromagnetic selector valve 68 switched to the channel opening position.

The above-mentioned pressure sensor 66 is to an input terminal of a control unit 71 connected. The electromagnetic selector valve 68 is to an output terminal of the control unit 71 connected.

The control unit 71 is designed to match the position of the slider of the control valve of the independent attachment circuit 37 changed on the basis of output signals which correspond to lever signals from an attachment operating unit 72 be transmitted, which may be an electrical control lever or similar unit. In addition, the control unit shifts 71 based on output signals associated with lever signal inputs of a main body actuator operating unit 73 correspond, which may be an electrical control lever or similar unit, the above-mentioned slide the main control valves 41 . 42 which serve to control the main assembly actuators.

The control unit 71 is designed so that only when signals from the pressure sensor 66 to the control unit 71 as a result of a high pressure, which is close to the relief pressure in the independent cultivation line 65 with simultaneous operation of the add-on operating unit 72 and the main body actuator operating unit 73 causes the output of electrical signals from the two working units, so that these signals at the same time at the control unit 71 come in, the control unit 71 electrical switching signals to the solenoid of the electromagnetic selector valve 68 transmits, causing it to switch the electromagnetic selector valve 68 in a channel opening position comes, so that by the second pump 33 into a canal 76 flowing hydraulic fluid through the external channel 67 in the tank 39 flows.

Between the left-hander main control valve 41 and the right turn main regulator valve 42 there is a bypass channel 74 in which a bypass valve 75 is installed. The bypass valve 75 is designed so that only when the pressure in the independent cultivation management 65 near the relief pressure increases, while the attached operating unit 72 and the main body actuator operating unit 73 operated simultaneously, the solenoid of the bypass valve 75 electrical signals from the control unit 71 receives, so that the bypass valve 75 switches from the channel occluding position to a channel opening position, whereby the bypass channel 74 is opened.

Below is the function of in 1 illustrated embodiment with reference to the 2 explained.

If on the flow divider gate valve 43 acts an external force and thus exerts influence on its movement, the hydraulic fluid is constant to a port A11 and a port A22 of the pressure compensating valves 44 . 45 transported in a uniformly divided flow rate, as that of port P1 through the internal oil passage 52 to the port A1 running oil channel and the port P2 through the internal oil passage 54 to the port A2 extending oil channel always has the same opening properties.

With simultaneous movement of the hydraulic excavator and actuation of its attachment is by the pressure compensating flow divider valve 38 Ensures that the hydraulic fluid at the same flow rate is constant from the first pump 32 and the second pump 33 to the independent attachment circuit 37 flows, leaving the first main circuit 35 and the second main circuit 36 be supplied with hydraulic fluid same flow rate. Consequently, the vehicle does not deviate from its straight-ahead travel, because the flow rate of the hydraulic fluid from the left-hand control spool of the first main control valve 41 to the left movement motor is always identical with the flow rate of the hydraulic fluid, that of the right-motion spool of the second main control valve 42 flows to the right motion motor.

If the pressure in the independent attachment circuit 37 during simultaneous operation of the attachment operating unit 72 and the main body actuator operating unit 73 for the simultaneous actuation of the actuators of the attachment and the main body approaching the relief pressure, the pressure sensor detects 66 the pressure rise and emits corresponding signals to the control unit 71 ,

At the same time the control unit emits 71 Operating signals to the electromagnetic selector valve 68 so that it switches to a channel opening position when the external channel 67 with the tank 39 communicated. As a result, escapes from the priority channel in the external channel 67 branched hydraulic fluid through the electromagnetic selector valve 68 in the tank 39 and reduces the pump discharge pressure of the second pump 33 , The above-mentioned priority channel in the pressure balance flow divider valve 38 serves to receive the hydraulic fluid from the second pump 33 comes. As the pump relief pressure drops, the flow rate of the second pump increases 33 discharged fluids, and in the PQ diagram in 2 Flow rate shown shifts from point Pa to point Pb.

At the same time, the pressure drops in the canal 76 to a displacement of the pressure compensation valve 45 to the right, as in 1 shown, so that the supply of hydraulic fluid to the independent attachment circuit 37 decreases while simultaneously supplying hydraulic fluid to the main circuit 36 increases. Therefore, compared to a conventional type hydraulic circuit, a much larger amount of hydraulic fluid flows through the main regulator valve 42 into the main construction actuators. This is the moment of approach of the pressure in the independent mounting circuit 37 during the concurrent operation of the actuators of the attachment and the main body does not cause the problem of an extreme slowing down of the movement of the actuators.

The phrase "the pressure in the attachment circuit is approximately equal to the relief pressure" describes that the attachment approaches the state of stall due to overloading, and as a result, the amount of hydraulic fluid required to maintain the circuit pressure will be sufficient, even if that of the second pump 33 discharged hydraulic fluid into the tank 39 flows. Consequently, the configuration of the invention described above is appropriate.

If, referring to 1 As the pressure in the attachment circuit approaches the relief pressure, the flow of hydraulic fluid is directed toward the main regulator valve 42 the Hauptaufbauaktuatoren increased by an amount which is substantially higher than that of the conventional type. However, since the amount of the main regulator valve 41 flowing hydraulic fluid as in the conventional way remains low, it remains at a maintenance of the status described above, a difference in the amount of hydraulic fluid.

The result: while the main control valve 42 As the actuators become faster, they remain the main control valve 41 belonging actuators slowly. If both main control valves 41 . 42 are equipped with an adjustable slide, there is a difference between the amount of hydraulic fluid in the right and left movement slide and thus to a deviation of the vehicle from the straight ahead.

However, according to the present invention, a departure from the straight travel can be prevented by the bypass valve 75 for forwarding through the right slide of the main control valve 42 flowing oil to the left movement slide of the main control valve 41 is used to achieve a balanced flow rate in this way. Since that in the main control valve 42 flowing oil through the bypass valve 75 also to other actuators of the main control valve 41 transported, the actuators can work faster than the conventional way.

Although the explanation given above refers to an example case where the external channel 67 Diverges from that priority channel, which is on the same side as the second pump 33 can be located between the pressure balance valve 44 and the check valve 46 on the side of the first pump 32 pulled an external channel and with the electromagnetic selector valve 68 get connected.

Corresponding The invention according to claim 1: When the pressure in the mounting circuit at a simultaneous operation of the actuators of the attachment and the The main structure approaches the relief pressure, flows from the pressure compensating flow divider valve to the external channel branched priority hydraulic fluid through the Selection valve in the tank and increases the flow rate of the pump, allowing a larger amount Hydraulic fluid flows to the main assembly actuators. Consequently, occurs in the Implementation of the invention does not solve the problem that the action of Main construction actuators becomes extremely slow in that moment in which at a simultaneous operation of the actuators of the attachment and the main construction of the pressure in the cultivation circuit the relief pressure approaches, so that with the help of the invention the working efficiency of the construction machine elevated can be.

Corresponding Claim 2 of the invention is a simultaneous movement the hydraulic excavator and an operation of its attachment by the Pressure compensation flow dividing valve Ensures that constant hydraulic fluid at the same flow rate transported in the first and in the second main circuit becomes. As a result, the flow rate of the left-hand movement spool of the first main circuit to the left-hand drive fluid hydraulic fluid always identical to the flow rate of the right-hand movement spool of the second main circuit to Right-hand drive motor flowing Hydraulic fluid is, can with the invention deviations of the construction machine from the straight ahead be avoided.

Claims (2)

Hydraulic circuit for a construction machine comprising: main circuits ( 35 . 36 ) for controlling a tank ( 39 ) by means of pumps arranged on the construction machine ( 32 . 33 ) pumped up hydraulic fluid, whereby the hydraulic fluid is supplied to the main body arranged on the construction machine main body actuators; a mounting circuit ( 37 ) for controlling with the pumps ( 32 . 33 ) from the tank ( 39 ) upwardly pumped hydraulic fluid, whereby the hydraulic fluid is supplied to a mounted on the construction machine attachment part; a pressure compensating flow divider valve ( 38 ), which is adapted to the pressure of the pump ( 32 . 33 ) hydraulic fluid to be compensated and divided, so that it in the main circuits ( 35 . 36 ) and the mounting circuit ( 37 ), characterized in that it further comprises an external channel ( 67 ) for returning the pressure equalizing flow dividing valve ( 38 ) the mounting circuit ( 37 ) supplied hydraulic fluid into the tank ( 39 ) and a selector valve ( 68 ) in the external channel adapted to switch from a channel closing position to a channel opening position when the mounting circuit pressure is raised to a level nearly equal to that in the course of operating the attachment together with the main body actuators a relief pressure is. Hydraulic circuit according to Claim 1, characterized in that the pumps are a first pump ( 32 ) and a second pump ( 33 ) contain; the main circuits have a first main circuit ( 35 ) including a left-hand reel for controlling a left-hand hydraulic motor of the machine body and a second main circuit (FIG. 36 ) including a right-hand motion coil for controlling a right-hand motion hydraulic motor of the machine body; and that the pressure compensating flow divider valve ( 38 ) a single flow dividing spool valve ( 43 ) which is adapted to control the hydraulic fluid so that the hydraulic fluid from the first pump ( 32 ) the first main circuit ( 35 ) and the second pump ( 33 ) the second main circuit ( 36 ) and the mounting circuit ( 37 ) is supplied at the same flow rate.