JPH05240208A - Valve device - Google Patents

Abstract

PURPOSE: To make a plurality of hydraulic users not so different in speed by providing a valve which operates one or more priority users by distributing pressurized fluid in a valve device to control a plurality of hydraulic users mounted on construction equipment. CONSTITUTION: The valve device mounted on an excavator has a control spool valve 1 for a turning gear, and control spool valves 2, 3 for the boom and dipper, and is provided with controllers 4-6 for control of the control spool valves 1-3. The control conduits 7, 8 for the controller 4 have junction conduits 7a, 8b communicating with a shuttle valve 15, the outlet of the shuttle valve 15 being connected to the control junction of a two-way valve 17 via a control conduit 16. The outlet B of the two-way valve 17 is connected to a reservoir conduit 20 via a pressure control valve 18, while the inlet A is connected to a control conduit 10 provided with a check valve 23, a throttle 24 and a controller 5 via a control conduit 22. Operation of the boom and dipper is restricted by the operation of the two-way valve 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for supplying a pressure medium to a hydraulic control system for the purpose of controlling a plurality of simultaneously operated hydraulic consumers that are independent of load. A valve device of the type in which the partial flow ratio, once adjusted, remains unchanged in the event of an undersupply of pressure medium to the system.

[0002]

A valve device of this type is disclosed in DE-A-3634728.

Construction machines, in particular excavators, require the individual hydraulic consumers, such as rotating devices, booms, dippers and buckets, to be operated independently of each other and partially simultaneously. In independent operation of these hydraulic consumers independently of one another, the hydraulic consumer can be supplied with the maximum amount of pressure medium available as required. In parallel operation, i.e. where uniform speed of the pressure consumer is desired, the maximum pressure medium volume must be distributed evenly to the pressure consumer. In any of the operation types, it is desirable that the hydraulic consumer operates independently of the load.
For example, in excavator control, a high speed of each equipment, such as a boom or a dipper, is required during an individual operation, whereas it is desirable that the speed of the rotating device is set relatively low. In the case of parallel operation such as loading, it is desirable that the boom, the dipper, and the rotating device move at substantially the same speed. In order to simplify such operations, it is desirable that this is automatically ensured during maximum displacement of the controller.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve device in which the quantity distribution ratio during parallel operation of a plurality of hydraulic power consumption devices is changed at the time of insufficient supply to give priority to a specific hydraulic power consumption device. It is to be. For example, it is desirable that two hydraulic consumers, which are supplied with significantly different amounts during individual operation, move at substantially the same speed during parallel operation regardless of load. It is desirable that such a volume distribution ratio be maintained even when the pressure medium is insufficiently supplied.

Example: Excavator control Individual operation Boom 400 l / min; Dipper 400 l / min; Rotating device 200 l / min.

A high individual speed is desired for each piece of equipment, for which the amount of rotating equipment must be set relatively small.

A typical course of motion, such as occurs during loading, requires parallel operation of the boom, rotator and dipper.

In this case, in order to improve the controllability, it is desirable that the speeds of the three hydraulic consumers do not differ too much.

[0009]

In order to solve this problem, in the structure of the present invention, the control pressure for operating one or a plurality of control valves for the hydraulic consumer which is preferentially operated is different. Is designed to control the valve of
The distribution of the pressure medium flow is made so that one or more hydraulic consumers are preferentially operated.

[0010]

According to the present invention, when the amount of pressure medium required by the controller becomes larger than the maximum discharge amount of the control pump, the hydraulic consumer of the higher rank in the operation priority rank is required. Gained amount or speed, while
Lower-ranking hydraulic consumers can obtain only the maximum residual amount.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a control spool valve used for a rotating device, and reference numerals 2 and 3 indicate control spool valves used for a boom and a dipper. The control of the control spool valve is performed via the controllers 4, 5 and 6. These controllers are control conduits 7, 8, 9, 1
Control spool valves 1, 2, 3 via 0, 11, 12.

The control conduits 7, 8 of the controller 4 are shuttle valves 1
It has branch conduits 7a and 8a which communicate with 5. The outlet of this shuttle valve leads via a control line 16 to the control connection of a valve 17 which is designed as a two-way valve. Valve 1
The opposite side of 7 is loaded by an adjustable compression spring 19. The outlet B of the valve 17 leads to a tank conduit 20 via a pressure limiting valve 18. The inlet A of the valve 17 is a control conduit 22
To the check valve 23, the throttle 24 and the control conduit 10 with the controller 5. This controller 5 shifts the control spool valve 2 to the switching position a via the control branch conduit 25, so that the bottom surface of the boom cylinder is loaded at this switching position. Furthermore, the inlet A is provided with a throttle 28 via a check valve 26 and a control conduit 1 with a controller 6 for a dipper.
1 is connected to. In this case, the control pressure in this control conduit 11 shifts the control spool valve 3 to the switching position a,
The bottom surface of the dipper cylinder is loaded at this switching position. The outlet B of the valve 17 is connected to the inlet of the pressure limiting valve 18. In the illustrated switching position of the valve 17, both connections, i.e. the connection between the inlet A and the outlet B, are cut off and thus also the pressure limiting valve 18 and thus the tank conduit 20. The control pressure acting from the controller 4 for the control spool valve 1 for the rotating device is
When it propagates to the control side of the valve 17 via the shuttle valve 15 and exceeds a specified switching pressure that can be adjusted by the compression spring 19, the valve 17 is switched from the shut-off position shown to the flow-through position. There is. As a result, the control conduit 25 for the control spool valve 2 used on the underside of the boom and the control conduit 30 for the control spool valve 3 used on the dipper are of the extent defined by the pressure limiting valve 18. Only a large control pressure is created. Therefore, the pressure limiting valve 18 defines the maximum flow opening of the control spool valves 2, 3 for the bottom of the boom cylinder and the dipper cylinder, and thus the maximum withdrawal speed of these cylinders. When the valve 17 is in the shut-off position shown, the pressure limiting valve 18 does not act on the control liquid of the control spool valves 2 and 3. Therefore,
These control spool valves can be fully displaced by the controllers 5,6. The hydraulic fluid for the hydraulic consumer is supplied by a variable displacement pump 31. The hydraulic fluid supplied by the variable displacement pump 31 is supplied via pump conduits 32 to the individual control spool valves 1, 2 and 3 and to the control spool valves for the buckets and the traveling equipment.

In order to perform control independent of load, a pressure balance 33 having a switching valve 34 on each control spool valve is provided.
Are assigned. By means of the diverter valve 34, the individual pressure balances are in each case loaded on the spring side with the maximum load that occurs, so that when the overall control is under-fed, i.e. based on the position of the control spool valve, more than the pump can deliver. If a large amount of working fluid is required, the maximum pump delivery provided is distributed to the hydraulic consumer corresponding to each cross-section opening of the control spool valve.

Control conduits 10 for boom and dipper,
The throttles 24, 28 arranged at 11 are connected to the conduit section 2 behind the throttle when the pressure limiting valve 18 is open.
5 and 30 ensure that a limited pressure is produced, as regulated by the pressure limiting valve 18.

The mode of operation of the control shown in FIG. 1 will be described in detail with reference to FIG. The diagram shown in FIG.
The axis shows the control of the hydraulic consumer in chronological order. The Y-axis indicated by the symbol q shows the amount or speed of each hydraulic consumer.

In the loading process, the operator operates the controller to the end position for the purpose of simplifying the operation. In the individual operation, each hydraulic power consumption device reaches the maximum speed defined by the control valve cross-sectional area or the maximum pump discharge amount.
In this embodiment, it is assumed that the beam and the dipper, which are hydraulic power consumers, can reach the maximum speed of 300 l / min during the individual operation, and the rotary device that is preferentially operated can reach the maximum speed of 200 l / min. Since the maximum pump discharge rate is assumed to be 400 l / min, when parallel operation of the hydraulic consumers,
As soon as the overall speed exceeds 400 l / min, an undersupply occurs.

At time A shown in FIG. 2, the controller 5 for controlling the switching position a of the control spool valve 2 for the boom is operated to the end position. At this time, the control conduit 1
The control pressure in 0,25 reaches a maximum value, for example 30 bar, and the control spool valve for the boom is in the end position (10
Open up to 0%). The variable displacement pump 31 swivels well and the boom reaches a maximum speed of 300 l / min by time B.

At time point C, the controller 4 used in the control spool valve for the rotating device is operated to the end position. The control pressure in the control lines 7, 8 likewise reaches a value of 30 bar, so that the control spool valve 1 for the rotating device opens to the end position.

At the time point D, the variable discharge pump 31 is set to 4
It delivers a maximum delivery of 00 l / min, in which case the boom still maintains 300 l / min and the rotating device
Reach 001 / min.

In the known control system which does not have the priority control, the shortage supply control operates at this time point D, and the maximum pump discharge amount is distributed to the rotating device and the boom in equal proportions according to the nominal amount. Such quantity distribution is indicated by a dashed line.

In the configuration of the present invention, the priority control becomes effective at the time point D. In this case, the control pressure for the rotary device of the higher rank which is desired to be operated preferentially is also guided to the valve 17 via the shuttle valve 15. , The valve is switched to the open position when the regulated compression spring force, eg 19 bar, is exceeded. This reduces the control pressure of 30 bar for the boom to a low maximum control pressure of about 20 bar, which is regulated by a pressure limiting valve 18 arranged downstream of the valve 17 and consequently of the boom. The control spool valve 2 for is reduced to about 66% of its nominal cross-sectional area. This will allow the boom speed to range from 300 l / min
It is reduced to minutes. Maximum discharge of control pump is 400
Since it is l / min, the rotating device is provided with 200 l / min which is required for its maximum speed. Therefore,
The boom speed was reduced from 300 l / min to about 200 l / min, and the rotating device speed was reduced from 100 l / min to 20 l / min.
Climb to a maximum speed of 0 l / min. Due to the control pressure at the boom being limited to 20 bar, an undersupply to the hydraulic consumer does not yet occur. At time point E, the dipper is additionally operated to its end position, so that the control spool valve of the dipper is only loaded with a maximum control pressure of 20 bar corresponding to the adjustment in the pressure limiting valve 18 at 400 l / l. A maximum pump delivery of minutes is no longer sufficient to supply the hydraulic consumer with the required amount of working fluid. Therefore, the shortage supply control is activated at this time, and in this case, the control spool valve 1,
A pressure balance 33, which is associated with a few measuring shields and which is controlled in the closing direction by the maximum load pressure, takes over the distribution function in response to the opening of the control valve. Therefore, the maximum pump displacement is proportional to all three hydraulic consumers by pressure balance, that is, the rotating device, the boom and the dipper.
It is distributed according to the open cross-sectional area of the corresponding control spool valve.

By the time point F, the speed of the boom and the rotating device has been reduced from 200 l / min to about 133 l / min, respectively. On the other hand, the connected dipper is about 1
Since the speed is increased to 33 l / min, the boom, the rotating device and the dipper move at almost the same speed after the time point F is exceeded. By adjusting the pressure in the pressure limiting valve 18, it is also possible to adjust the speed of the upper-ranking hydraulic consumer to the speed of the lower-ranking hydraulic consumer which is preferentially operated in accordance with the parallel operation, to another prescribed ratio. ..

Naturally, the priority control can set the maximum speed of the boom or the dipper in the individual operation to a higher value (up to the maximum pump discharge rate of 400 l / min), and in this case, all the hydraulic pressures can be used in parallel operation. Equal speed on the consumer is not lost.

The description of FIG. 1 has been limited to the components that are important to an understanding of the present invention. Other hydraulic consumers, such as traveling equipment and buckets, are not critical to the understanding of the invention.

Instead of the valve 17 affecting the control pressure,
As described in claim 7, a three-way switching valve may be provided. This three-way directional valve has one inlet for the pump conduit 32 and two outlets for the upper and lower rank hydraulic consumers. In this case, the amount of partial flow is defined by the control pressure for the hydraulic consumer which is to be preferentially operated.

As an alternative to the three-way directional control valve provided in the pump conduit 32, a two-way directional control valve for lower rank hydraulic consumers can be incorporated. By this, it is only necessary to define the amount of partial flow for the lower-ranking hydraulic consumer. Further, as described in claim 5, the valve 17 and the pressure limiting valve 18 can be configured as a pressure proportional valve having both functions.

[Brief description of drawings]

FIG. 1 is a circuit diagram for controlling an excavator.

FIG. 2 is a diagram showing a quantity distribution with respect to a boom, a rotating device, and a dipper of an excavator as a function of speed and time.

[Explanation of symbols]

1, 2, 3 control spool valve, 4, 5, 6 controller,
7,8,9,10,11,12 control conduit, 7a,
8a branch conduit, 15 shuttle valve, 16 control conduit, 17 valve, 18 pressure limiting valve, 19 compression spring, 20 tank conduit, 22 control conduit, 23
Check valve, 24 throttle, 25 control branch conduit, 26
Check valve, 28 throttle, 30 control conduit, 31
Variable discharge pump, 32 pump conduits, 33 pressure balance, 34 switching valve

Claims (8)

[Claims] 1. A valve device for controlling a plurality of hydraulic consumers regardless of load, wherein a discharge amount of a pressure medium source configured as a control pump is a load pressure (L) of the hydraulic consumer.
The control valve (1, 2, 3), which is adjustable independently of S) and which is associated with the hydraulic consumer and is hydraulically controllable, is controlled by the controller (4, 5, 6) configured as a pressure control valve. In the controllable form, the control pressure for operating one or more control valves for the hydraulic consumer that is preferentially operated is such that another valve (17) is controlled. A valve device for distributing the pressure medium flow such that one or more hydraulic consumers are preferentially operated. 2. The valve (17) is loaded from the closed position in the opening direction by the control pressure to operate the control valve (1, 2, 3) of the hydraulic consumer of a lower rank in the operation priority rank. 2. The valve device according to claim 1, wherein the maximum attainable control pressure of the valve is switched to a lower value. 3. A pressure limiting valve (18) is arranged downstream of the valve (17) for delivering the control liquid.
Or the valve device according to 2. 4. The valve (17) is loaded in the closing direction by an adjustable compression spring (19).
Or the valve device according to 2. 5. The valve arrangement according to claim 1, wherein the valve (17) is a pressure proportional valve. 6. A relatively low control pressure level is adjusted for the lower-rank hydraulic consumer so that the speed of the lower-rank hydraulic consumer to be operated substantially matches the speed of the higher-rank hydraulic consumer. The valve device according to any one of claims 1 to 5, wherein: 7. The valve (17) is configured as a continuously adjustable three-way switching valve, which directs the pressure medium flow into a higher-rank flow and a lower-rank flow. 7. A valve device according to any one of claims 1 to 6, adapted to dispense. 8. A valve according to any one of claims 1 to 7, wherein the valve (17) is adapted to act as a two-way metering valve for supplying a partial flow for a lower-rank hydraulic consumer. The valve device according to item 1.