JPH11131532A - Control circuit for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an interlocking property between a standard actuator and the actuator of an attachment in a construction machine. SOLUTION: The ratio between the flow rate of hydraulic oil that is supplied to a standard valve 41 and the flow rate of hydraulic oil that is supplied to an attachment valve 43 from a pump 31 is controlled by a flow rate distribution valve 45. The standard valve 41 controls hydraulic oil supplied to a standard actuator that is used for excavation of a hydraulic shovel. The attachment valve 43 controls hydraulic oil supplied to an attachment actuator that is used for application expanding work. On the basis of signals detected by a pump discharge pressure sensor 63 that detects the discharge pressure of the pump 31, a standard pressure sensor 64 that detects load pressure of the standard valve 41 and an attachment pressure sensor 65 that detects the load pressure of the attachment valve 43, an electromagnetic proportional valve 55 is controlled by a controller 75. The electromagnetic proportional valve 55 converts electrical signals outputted from the controller 75 to hydraulic signals and controls the flow rate distribution valve 45 by pilot pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a construction machine to which an attachment used for a task with an expanded use can be mounted.

[0002]

2. Description of the Related Art As shown in FIG. 2, a hydraulic excavator is provided with a lower traveling body 13 having a crawler belt 12 driven by a traveling motor 11 via a pivot bearing 15 driven by a pivot motor 14. An upper revolving unit 16 is provided so as to be freely rotatable. The upper revolving unit 16 is provided with a cab 17 provided with an operator's driver's seat and a front work machine 18 for excavation work.

[0003] A front work machine 18 is provided with a pin
The boom 20 is rotatably supported by 19, and this boom 20
A stick 22 is rotatably supported at the tip of the stick 22 by a pin 21, and a bucket 24 is
The boom 20 is rotated by a boom cylinder 25, the stick 22 is rotated by a stick cylinder 26, and the bucket 24 is rotated by a bucket cylinder 27 and a link mechanism 28.

[0004] The bucket 24 is detachable, and an attachment 29 such as a hydraulic hammer or a hydraulic crusher is attached in place of the bucket 24, and the hydraulic shovel is expanded to other uses other than the excavation work.

In such a hydraulic excavator, the traveling motor 11, the swing motor 14, the boom cylinder 25, the stick cylinder 26, and the bucket cylinder 27 are used as a standard excavator because they are used for the original excavation work of the hydraulic excavator.

On the other hand, a hydraulic cylinder or a hydraulic motor built in an attachment 29 such as a hydraulic hammer or a hydraulic crusher, which is mounted in place of the bucket 24 and expands applications other than excavation work, is used as an actuator of the attachment.

The hydraulic oil supplied from the pump 31 to various standard actuators is controlled by standard valves such as a traveling spool 32, a turning spool 33, a boom spool 34, a stick spool 35, and a bucket spool 36. Is done.

The hydraulic oil supplied from the pump 31 to the actuators of various attachments is controlled by attachment valves such as a first attachment spool 37, a second attachment spool 38, and a third attachment spool 39.

[0009]

Generally, attachments
Attachment actuators for driving the attachment actuators 29 are added as needed, and when the spools 32 to 39 are open centers, the standard valves (32 to 36 ) And the attachment valve (37-39) to share the discharge oil from the pump 31,
Hydraulic oil is supplied only to the standard actuator, or vice versa, and the interlock is lost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to secure interlocking between a standard actuator and an attachment actuator in a construction machine.

[0011]

The invention described in claim 1 controls a pump and hydraulic oil supplied from the pump to a standard actuator used for standard work (such as excavation) of a construction machine. A standard valve, an attachment valve that controls the hydraulic oil supplied from the pump to an attachment actuator used for versatile work, and a variable control of the ratio of the hydraulic oil flow supplied from the pump to the standard valve and the attachment valve. 3 is a control circuit of a construction machine including a flow distribution valve.

When the standard actuator and the attachment actuator are linked, the hydraulic oil flow supplied from the pump to the standard actuator via the standard valve and the hydraulic oil supplied to the attachment actuator via the attachment valve The ratio with the flow rate is variably adjusted by the flow distribution valve.

According to a second aspect of the present invention, in the control circuit for a construction machine according to the first aspect, a pump discharge pressure sensor for detecting a discharge pressure of a pump and a standard actuator pressure for detecting a load pressure of a standard actuator. A sensor, an attachment actuator pressure sensor for detecting a load pressure of the attachment actuator, and a controller for controlling the flow distribution valve based on detection signals detected by the pump discharge pressure sensor, the standard actuator pressure sensor, and the attachment actuator pressure sensor. This is a control circuit.

The controller detects the load pressure of the standard actuator and the attachment actuator from each signal detected by the pump discharge pressure sensor, the standard actuator pressure sensor, and the attachment actuator pressure sensor, and detects the standard valve and the attachment valve. The flow distribution valve is automatically controlled by performing arithmetic processing so that an appropriate amount flows to both sides, or the flow distribution valve is automatically controlled by performing arithmetic processing so as to give priority to the movement of one of the preset valves. The distribution valve adjusts the ratio of the hydraulic oil flow supplied to the standard valve and the attachment valve.

According to a third aspect of the present invention, in the control circuit for a construction machine according to the second aspect, an electric signal output from the controller is converted into a hydraulic signal to control the flow distribution valve by pilot pressure. It is a control circuit provided with a valve.

The controller detects the load pressure of the standard actuator and the attachment actuator from each signal detected by the various sensors, performs arithmetic processing, and outputs an electric signal to the electromagnetic proportional valve. The electromagnetic proportional valve converts the electric signal into a hydraulic signal and outputs it, controls the flow distribution valve proportionally by pilot pressure, and adjusts the ratio of the hydraulic oil flow supplied to the standard valve and the attachment valve by the flow distribution valve. I do.

According to a fourth aspect of the present invention, there is provided the control circuit for a construction machine according to the second or third aspect, further comprising a manual switch connected to the controller for starting automatic control of the flow distribution valve.

Then, the operator operates a manual switch as needed to start automatic control of the flow distribution valve,
You can also stop.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. The same parts as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, an attachment oil passage 44 extending from a standard oil passage 42 connecting the main pump 31 and the standard valve 41 to an attachment valve 43 is branched.

Further, the standard valve 41 and the attachment valve
The ratio of the hydraulic oil flow supplied from the main pump 31 to the standard actuator and the attachment actuator via the standard valve 41 and the attachment valve 43 is variable from the standard oil passage 42 upstream of the 43 to the attachment oil passage 44. A controlling flow distribution valve 45 is provided.

The standard valve 41, the attachment valve 43, and the flow distribution valve 45 form a one-block main control valve 46.

The standard valve 41 includes a traveling spool 32, a turning spool 33, a boom spool 34, and a stick spool.
Main pump consisting of 35 and bucket spool 36
Actuators supplied from 31 to standard actuators used for standard work of construction machines such as excavation, for example, various standard actuators such as travel motor 11, swing motor 14, boom cylinder 25, stick cylinder 26 and bucket cylinder 27. Control the oil.

The attachment valve 43 includes a first attachment spool 37, a second attachment spool 38, and a third attachment spool 39.
It controls hydraulic oil supplied to various attachment actuators such as a hydraulic cylinder or a hydraulic motor built in an attachment 29 such as a hydraulic crusher.

The flow distribution valve 45 has a flow distribution spool 47, and a pilot pressure chamber 48 facing one end face of the flow distribution spool 47 and an external pilot pressure guided to a pilot pressure chamber 49 facing the other end face. The position of the flow distribution spool 47 is controlled by the balance with the biasing force of the spring 50 provided on each end face of the spool.

For example, in the flow distribution spool 47, at the position a, the standard oil passage 42 is fully closed and the attachment oil passage 44 is fully opened, and at the position b, the standard oil passage 42 is adjusted according to the amount of movement of the spool. At the throttle position As, the attachment oil passage 44 is fully opened, at the position c, the standard oil passage 42 and the attachment oil passage 44 are fully opened, and at the position d, the standard oil passage 42 is fully opened and the attachment oil passage is opened. At 44, the standard oil passage 42 is fully opened and the attachment oil passage 44 is fully closed at the e position.

A pilot pump 51 driven by an engine (not shown) is connected to the main pump 31. A primary line 52 drawn from the pilot pump 51 is incorporated in one solenoid valve block 53. The outlet ports of these proportional solenoid valves 54, 55 are connected to the pilot pressure chamber 48 at one end of the flow distribution valve 45 by respective secondary lines 56, 57. And a pilot pressure chamber 49 at the other end.

These electromagnetic proportional valves 54 and 55 are provided with solenoids.
Converts electric signals input to 58 and 59 to hydraulic signals and outputs them to secondary lines 56 and 57, and controls flow distribution valve 45 by pilot pressure proportional to electric signals input to solenoids 58 and 59. It is. The drain ports of these proportional solenoid valves 54 and 55 are connected to a tank 61 by a drain line 60.

The pump discharge oil passage 62 between the discharge port of the main pump 31 and the branch point where the attachment oil passage 44 branches from the standard oil passage 42 has a pump discharge pressure for detecting the discharge pressure of the main pump 31. A sensor 63 is provided.

Furthermore, a standard actuator pressure sensor (hereinafter referred to as a sensor) for detecting a load pressure of hydraulic oil supplied to a standard actuator via the standard valve 41 is provided in a standard oil passage 42 communicating the flow distribution valve 45 and the standard valve 41. , Simply referred to as “standard pressure sensor”) 64.

Similarly, the flow distribution valve 45 and the attachment valve
Attachment oil pressure sensor (hereinafter simply referred to as “attachment pressure sensor”) 65 for detecting the load pressure of the hydraulic oil supplied to the actuator of the attachment via the attachment valve 43 is provided in the attachment oil passage 44 communicating with the attachment valve 43. Have been.

A manual switch 67 for starting automatic control of the flow distribution valve 45 is provided at a distal end of a control lever 66 for an operator in the cab 17 to operate the front work machine 18 and the like.

Then, these pump discharge pressure sensors 63,
The standard pressure sensor 64, the attachment pressure sensor 65, and the manual switch 67 are connected to the input terminal of the controller 75 by respective signal lines 71, 72, 73, 74.

The controller 75 has a central processing unit (C
PU), read only memory (ROM), random access memory (RAM), etc., and an amplification circuit for amplifying and outputting a signal. The pump discharge pressure sensor 63, the standard pressure sensor 64, and the attachment Pressure sensor
The arithmetic processing is performed based on the various detection signals detected by 65, and the flow distribution valve 45 is controlled via the electromagnetic proportional valves 54 and 55.

That is, the output terminal of the controller 75 is connected to the solenoids 58, 59 of the electromagnetic proportional valves 54, 55 by drive signal lines 76, 77. Each solenoid proportional valve 54,
The 55 converts the electric signal output from the controller 75 into a hydraulic signal, and controls the flow distribution valve 45 with the pilot pressure.

Next, the operation of the embodiment shown in FIG. 1 will be described.

When the operator operates the manual switch 67, the controller 75 starts automatic control by the flow distribution valve 45.

In this case, the pump discharge pressure sensor 63
The discharge pressure Po of the main pump 31 is detected, and a standard pressure sensor 64 is detected.
As a result, each spool 32 to the standard valve 41 passes through the flow distribution valve 45.
The load pressure Ps of the hydraulic oil supplied to 36 is detected, and the load pressure PA of the hydraulic oil supplied to each of the spools 37 to 39 of the attachment valve 43 via the flow distribution valve 45 is detected by the attachment pressure sensor 65.

The controller 75 includes a pump discharge pressure sensor 6
3. From the signals detected by the standard pressure sensor 64 and the attachment pressure sensor 65, the standard valve 41 detects the load pressure of the standard actuator that has passed through the standard valve 41 and the load pressure of the actuator of the attachment that has passed through the attachment valve 43. In order to supply an appropriate amount to both the attachment valve 43 and the attachment valve 43, how to control the flow distribution valve 45 through the electromagnetic proportional valves 54 and 55 is calculated, and an electric signal is output to the electromagnetic proportional valves 54 and 55.

For example, when the load pressure PA of the attachment oil passage 44 detected by the attachment pressure sensor 65 is larger than the load pressure Ps of the standard oil passage 42 detected by the standard pressure sensor 64, the flow distribution spool 47 is set to b. The two oil passages 42 and 44 are controlled by restricting the standard oil passage 42
A pair of solenoid proportional valves 5
4 and 55 are controlled by the controller 75.

The load pressure PA of the attachment oil passage 44
Is smaller than the load pressure Ps of the standard oil passage 42, the flow distribution spool 47 is controlled to the position d, and the attachment oil passage
The controller 75 controls the pair of electromagnetic proportional valves 54 and 55 so as to balance the load pressures of the two oil passages 42 and 44 by restricting the 44.

At this time, the controller 75 calculates the relationship among the hydraulic pressure, the flow rate and the spool opening by the following equation.

Qs = C · As · (Po−Ps) ^1/2 QA = C · AA · (Po−PA) ^1/2 where Qs is the flow rate required in the standard oil passage 42 and QA is the attachment. The flow rate required in oil line 44, C is a constant,
As and AA are flow distribution spools determined by signals output from the controller 75 via the proportional solenoid valves 54 and 55.
The opening area of 47, (Po-Ps) is the differential pressure between the pump discharge oil passage 62 and the standard oil passage 42, and (Po-PA) is the differential pressure between the pump discharge oil passage 62 and the attachment oil passage 44. It is.

Since the sum of the flow rate Qs of the standard oil passage 42 and the flow rate QA of the attachment oil passage 44 is equal to the discharge flow rate Qo of the main pump 31, when the ratio (Qs: QA) is set in the controller 75, Their values are also determined.
The differential pressures (Po-Ps) and (Po-PA) are values measured by the sensors 63, 64 and 65.

Thus, since the target opening area As or AA of the flow distribution spool 47 can be known, the electromagnetic proportional valve 54,
From 55, for the flow distribution spool 47, the opening areas As, A
A current value output from the controller 75 to the electromagnetic proportional valves 54 and 55 is calculated so that a predetermined pilot pressure signal corresponding to the stroke in which A is obtained is supplied.

Further, the controller 75 can send an intentional electric signal to the electromagnetic proportional valves 54 and 55 so as to give priority to the movement of either the standard valve 41 or the attachment valve 43 by setting in advance. it can.

In any case, the electromagnetic proportional valves 54 and 55 convert the electric signal from the controller 75 into a hydraulic signal and output the same, and control the flow distribution valve 45 proportionally with the pilot pressure. The ratio between the hydraulic oil flow Qs and the hydraulic oil flow QA supplied to the attachment valve 43 is determined by a flow distribution valve.
Automatically adjusted by 45.

As described above, the flow rate Qs of the working oil supplied from the main pump 31 to the standard valve 41 and the attachment valve
Flow rate distribution valve
By variably adjusting with 45, the linkage between the standard actuator and the attachment actuator is always ensured.

Finally, when the operator again operates the manual switch 67, the automatic control of the flow distribution valve 45 by the controller 75 is stopped. In this case, since the flow distribution valve 45 is maintained at the position c, the standard oil passage 42 and the attachment oil passage 44 are kept fully open, and the flow rate Q supplied to the standard valve 41 is reduced.
s and the flow rate QA supplied to the attachment valve 43 are determined by the load of the standard actuator and the actuator of the attachment, and a large amount flows toward the smaller load.

[0050]

According to the first aspect of the present invention, the ratio of the flow rate of hydraulic oil supplied from the pump to the standard valve and the attachment valve is variably controlled by the flow distribution valve.
Depending on the number of additional attachments and the size of the load,
Interlock between the standard actuator and the attachment actuator can be ensured.

According to the second aspect of the present invention, the controller determines each load pressure of the standard actuator and the attachment actuator from each signal detected by the pump discharge pressure sensor, the standard actuator pressure sensor, and the attachment actuator pressure sensor. Upon detection, the flow distribution valve can be automatically controlled, and the flow distribution valve can automatically adjust the ratio of the hydraulic oil flow supplied to the standard actuator and the attachment actuator via the standard valve and the attachment valve.

According to the third aspect of the present invention, since the electric signal output from the controller is converted to a hydraulic signal by the electromagnetic proportional valve and the flow distribution valve is controlled by the pilot pressure, a large flow is controlled by the flow distribution valve. The hydraulic oil flow required for the standard valve and the attachment valve can be secured.

According to the invention, the operator can easily start and stop the automatic control of the flow distribution valve by the controller only by operating the manual switch as needed.

[Brief description of the drawings]

FIG. 1 is an electric / hydraulic circuit diagram showing an embodiment of a control circuit for a construction machine according to the present invention.

FIG. 2 is a hydraulic circuit diagram showing a control circuit of a conventional hydraulic shovel.

[Explanation of symbols]

31 Pump 41 Standard valve 43 Attachment valve 45 Flow distribution valve 55 Proportional solenoid valve 63 Pump discharge pressure sensor 64 Standard actuator pressure sensor (standard pressure sensor) 65 Attachment actuator pressure sensor (attachment pressure sensor) 67 Manual switch 75 Controller

Claims (4)

[Claims] 1. A pump, a standard valve for controlling hydraulic oil supplied from a pump to a standard actuator used for a standard operation of a construction machine, and an actuator for an attachment used for a versatile operation from the pump. A control circuit for a construction machine, comprising: an attachment valve for controlling supplied hydraulic oil; and a flow distribution valve for variably controlling a ratio of a flow rate of hydraulic oil supplied from a pump to a standard valve and an attachment valve. 2. A pump discharge pressure sensor for detecting a discharge pressure of a pump, a standard actuator pressure sensor for detecting a load pressure of a standard actuator, an attachment actuator pressure sensor for detecting a load pressure of an attachment actuator, and a pump discharge. The control circuit for a construction machine according to claim 1, further comprising a controller that controls the flow distribution valve based on detection signals detected by the pressure sensor, the standard actuator pressure sensor, and the attachment actuator pressure sensor. 3. An electromagnetic proportional valve which converts an electric signal output from a controller into a hydraulic signal and controls the flow distribution valve by pilot pressure.
The control circuit of the construction machine according to the above. 4. The control circuit for a construction machine according to claim 2, further comprising a manual switch connected to the controller to start automatic control of the flow distribution valve.