JPH09166103A - Hydraulic control circuit - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To rotate a load in a forward direction or a reverse direction by a hydraulic actuator and control supply of hydraulic pressure to the hydraulic actuator by using a three-way control valve provided on a meter-in side and a meter-out side. In the control device, hunting is prevented, smooth deceleration is possible, and deceleration characteristics can be set arbitrarily. SOLUTION: A reference flow rate Qs on the meter-in side is calculated from an operation amount St of an operation device 32, and a hydraulic actuator 102 is calculated.
When the deceleration is required, the meter-out side pressure command value Pcom (M / O) is determined based on the deviation between the reference flow rate Qs and the meter-in side identified flow rate Qid (M / I), and the meter-out The brake pressure control is performed so that the load pressure (brake pressure) on the side matches the pressure command value Pcom (M / O). At this time, the load pressure on the meter-in side is pressure controlled to a predetermined value that does not prevent deceleration of the hydraulic actuator 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hydraulic control device for controlling the flow of hydraulic oil supplied to a hydraulic actuator by means of control valves provided on the meter-in side and the meter-out side.

[0002]

2. Description of the Related Art An actuator, such as an upper car body of a power shovel, which is operated by hydraulic pressure supplied from a pump, turns a load in a forward or reverse direction, and supplies hydraulic pressure to this actuator by using a three-way control valve. A hydraulic control device for pressure control is proposed in, for example, Japanese Patent Application No. 5-23792 filed by the present applicant.

In this conventional apparatus, the flow rate is controlled by the three-way control valve on the meter-in side after the turning direction of the actuator is determined. In this flow rate control, the opening degree of the three-way control valve is controlled based on the deviation between the feedback load flow rate identified from the load pressure, the pump discharge pressure, and the opening area of the three-way control valve, and the flow rate command value.

On the other hand, on the meter-out side, pressure control for adjusting the opening of the three-way control valve on the meter-out side is performed so that the load pressure on the meter-in side is maintained at a predetermined target value.
That is, when the load pressure on the meter-in side is higher than the target value, for example, when a positive load is applied to the actuator during leaning and turning, the opening of the three-way control valve on the meter-out side is opened and the meter-in side is opened. Reduce the load pressure of. On the other hand, when the load in the negative direction is applied and the load pressure on the meter-in side becomes lower than the target value, the opening of the three-way control valve on the meter-out side is reduced to increase the load pressure on the meter-in side.

[0005]

By the way, in the pressure control on the meter-out side, the three-way control valve on the meter-out side performs the same function as the counter balance valve, and the pressure on the meter-in side is higher than the target value. If it goes down, the opening of the three-way control valve on the meter-out side is throttled, and if it goes above the target value, it opens and the opening is adjusted according to the deviation from the target value of the load pressure on the meter-in side. Since it does not have, there is a drawback that it tends to be an on-off movement. For this reason, brake pressure is generated on and off particularly when the actuator is decelerated, and hunting occurs, which prevents smooth deceleration, which impairs the operability of the actuator.

Further, since the load swung by the actuator often has a large inertia, when the actuator is stopped from the swung state, the pressure due to the inertia of the load remains on the meter-out side, and the swing-back phenomenon occurs. Had happened.

The present invention focuses on such problems,
In a hydraulic control device that controls the supply of hydraulic pressure to this actuator using a three-way control valve by rotating the load in the forward or reverse direction with an actuator that operates with the hydraulic pressure supplied from the pump, smooth hunting is prevented. An object of the present invention is to provide a hydraulic control device that enables deceleration and that can set the deceleration characteristic arbitrarily.

[0008]

As shown in FIG. 8, a first invention is a hydraulic actuator 102 which receives a hydraulic pressure from a pump 101 to drive a load, and a first circuit 1 side of the hydraulic actuator 102. A first three-way control valve 103 for switching and connecting the tank 100 side and the pump 101 side with respect to the hydraulic actuator 102, and the tank 100 with respect to the hydraulic actuator 102 provided on the second circuit 2 side of the hydraulic actuator 102. Side and pump 10
A second three-way control valve 104 for switching and connecting one side, and first and second load pressure detecting means 105 for detecting load pressure on the hydraulic actuator 102 side of the first and second three-way control valves 103, 104. , 106, supply pressure detection means 107 for detecting the supply pressure of the first and second three-way control valves 103, 104 on the pump 101 side, and the opening degrees of the first and second three-way control valves 103, 104. First and second to detect
Of the opening degree detection means 108 and 109, and the identification flow rate calculation means 1 for calculating the identification flow rate flowing through the meter-in side and the meter-out side of the hydraulic actuator 102 from these detection signals.
10 and operation amount detection means 11 for detecting the operation amount of the operation device
1, a turning direction determining means 112 for determining a turning direction of the hydraulic actuator 102, a reference flow rate calculating means 113 for setting a reference flow rate flowing on the meter-in side of the hydraulic actuator 102 based on the operation amount, and a hydraulic pressure from the operating device. The deceleration determination means 114 that determines that a deceleration request has been issued to the actuator 102, and the meter-out side of the hydraulic actuator 102 based on the deviation between the reference flow rate and the identified flow rate on the meter-in side of the hydraulic actuator 102 when decelerating the hydraulic actuator 102. The hydraulic actuator 1 while setting the pressure command value for the pressure of
02, the pressure command value calculating means 115 that sets a predetermined pressure command value that does not prevent deceleration of the hydraulic actuator 102, and the first and second three-way control valves based on the pressure command value. An opening degree command value calculating means 116 for setting an opening degree command value for the opening degrees of 103 and 104;
Based on this opening command value, the first and second three-way control valves 10
The first and second valve spool driving means 117 and 118 for driving the valve spools 3 and 104 are provided.

The second invention is a hydraulic actuator 102.
When the meter stops after decelerating, the opening degree of the three-way control valve 103 or 104 on the meter-out side is set so that the pressure value on the meter-out side does not cause reverse rotation of the hydraulic actuator, and the reference flow rate on the meter-in side and the meter-in side. The pressure is controlled so as to increase as the deviation of the identification flow rate on the side increases.

[0010]

In the first aspect of the invention, the operation amount detecting means 111 detects the operation amount of the operating device, and the turning direction determining means 11 is also provided.
The turning direction of the hydraulic actuator 102 is determined by 2 and, of the first and second three-way control valves 103 and 104,
It is determined which is the meter-in side and which is the meter-out side. Subsequently, the reference flow rate calculation means 11
By 3, the reference flow rate on the meter-in side corresponding to the operation amount of the operation device is set. Further, based on the first and second load pressure detecting means 105 and 106, the supply pressure detecting means 107, and the first and second opening degree detecting means 108 and 109, the identification flow rate calculating means 110 causes the meter-in side of the hydraulic actuator 102. Deceleration determination means 114
Determines whether a deceleration request for the hydraulic actuator has been issued based on the identified flow rate and the operation amount of the operating device. As a result, if it is determined that the deceleration request is issued to the hydraulic actuator 102, the pressure command value calculation means 115 causes the three-way control valve 104 on the meter-out side based on the deviation between the identified flow rate on the meter-in side and the reference flow rate. A pressure command value for 103 is set, and for the three-way control valve 103 or 104 on the meter-in side, a pressure command value that does not prevent deceleration of the hydraulic actuator 102 is set. Further, the opening degree command value calculation means 116
Thus, the opening command values corresponding to these pressure command values are set, and the first and second valve spool drive means 117, 118 set the first and second three-way control valves in accordance with the opening command values. Pressure control is performed to control the opening degrees of 103 and 104. At this time, the brake pressure generated on the meter-out side is determined based on the deviation between the reference flow rate on the meter-in side and the identified flow rate. The larger the deviation, the higher the brake pressure, and the smaller the deviation, the lower the brake pressure. As described above, the three-way control valve 103 or 104 on the meter-out side does not control the pressure on and off, and the hydraulic actuator 102 is gradually operated.
You can smoothly decelerate.

In the second aspect of the invention, the brake pressure is generated in accordance with the deviation between the reference flow rate on the meter-in side and the identified flow rate on the meter-in side for smooth deceleration control, while when the hydraulic actuator 102 stops after deceleration. , The three-way control valve 103 or 104 on the meter-out side is controlled to such an extent that the pressure value on the meter-out side does not cause reverse rotation of the hydraulic actuator 102, so that the pressure remaining on the meter-out side is released and the hydraulic actuator 102 It can prevent shaking back.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a hydraulic motor 10 is provided as a hydraulic actuator that operates by receiving hydraulic oil supplied from a pump P. The hydraulic motor 10 has a first circuit 1 and a second circuit 2. Are connected. In this hydraulic motor 10, the first circuit 1 is connected to the meter-in side and the second circuit 2 is connected.
To the right turn mode with the meter-out side as the second circuit 2
The left turn mode in which the first circuit 1 is on the meter-in side and the first circuit 1 is on the meter-out side can be set.

A first three-way control valve 11 and a second three-way control valve 12 are provided in the first circuit 1 and the second circuit 2, respectively. These three-way control valves 11 and 12 take the valve positions a, b, c, and d according to the displacement of the spool 15 so that the C ports 3 and 4 communicating with the hydraulic motor 10 communicate with the tank T, respectively. T ports 5 and 6 or P ports 7 and 8 communicating with the pump P are switched and connected.

Since the three-way control valves 11 and 12 have exactly the same structure, only the three-way control valve 11 is shown in FIG. 2, and the three-way control valve 11 will be described below.

As shown in detail in FIG. 2, the valve position a
Is the valve position when the power is off, and at this valve position, C port 3, T port 5, and P port 7 are all blocked. Therefore, the flow of hydraulic oil through the three-way control valve 11 does not occur, and the load pressure of the C port 3 continues to be maintained.

Further, the valve position b is set to the hydraulic motor 10
This is the valve position of the three-way control valve 11 on the meter-out side during the driving of. At the valve position b, the C port 3 to the T port 5 are moved depending on the sliding position of the spool 15.
The communication opening area to the C port 3 is adjusted so that the pressure of the C port 3 can be controlled.

The valve position c is a valve position in the neutral state of the hydraulic motor 10, and is used when the hydraulic motor 10 is temporarily stopped although the power is not turned off. Here, the P port 5 is blocked, and at the same time, the check valve 13 is interposed between the C port 3 and the T port 5 to prevent the backflow of the hydraulic oil from the C port 3 to the T port 5. As a result, the load pressure is maintained,
The hydraulic motor 10 is kept stopped.

Further, the valve position d corresponds to the hydraulic motor 1.
This is the valve position of the three-way control valve 11 on the meter-in side when 0 is driven. In this valve position, the hydraulic oil from the P port 7 can spread the check valve 13 and flow into the C port 3. Also, from C port 3 to T
A bleed flow rate is also generated for the port 5 via the orifice 14.

A stepped portion 16 is provided at the left end of the spool 15.
Is formed, and the stepped portion 16 forms a small pressure-receiving area chamber 17
And a large pressure receiving area chamber 18 are defined. Small pressure receiving area chamber 17
While the discharge pressure from the pump P is directly transmitted to, the adjustment pressure obtained by adjusting the pump discharge pressure is transmitted from the pilot valve 21 or 22 to the large pressure receiving area chamber 18, and the force due to these pressures is transmitted. The spool 15 is displaced according to the balance with the force acting from the spring 19.

Now, the three-way control valve 1 thus constructed
The opening degree of 1 and 12 (stroke displacement of the spool 15) is
It is detected by the stroke sensors 23 and 24, respectively. Further, pressure sensors 25 and 26 are provided at the C ports 3 and 4 of the three-way control valves 11 and 12, respectively, and the load pressures of the first circuit 1 and the second circuit 2 are detected respectively. The pressure sensor 27 can also detect the discharge pressure of the pump P.

Based on these detection results, the controller 30 calculates the identified flow rate flowing through the C port 3 or 4. This identified flow rate is determined from the pressure difference between the C ports 3 and 4 of the three-way control valves 11 and 12 and the P ports 7 and 8 and the communication opening area between these ports from the C ports 3 and 4 to P
It is calculated by subtracting the pressure difference between the C ports 3 and 4 and the T ports 5 and 6 and the bleed flow rate obtained from the communication opening area between these ports from the flow rate of the hydraulic oil flowing to the ports 7 and 8. . The pressures of the T ports 5 and 6 may be calculated assuming that they are released to the atmospheric pressure.

An operation signal corresponding to the operation amount is input to the controller 30 from the operation device 32. In the pressure control, the controller 30 sets the three-way control valve 1 so that the pressure command value determined according to this operation signal matches the measured pressure of the C ports 3, 4 of the three-way control valves 11, 12.
The opening command value for 1 or 12 is determined. The opening command value is input from the controller 30 to the pilot valve drive circuit 33 or 34, and the pilot valve drive circuit 33 or 34 detects the opening command value and the three-way control valve 11 or 12 detected by the stroke sensor 23 or 24. Pilot valve 2 based on the deviation from the opening
1 or 22 is driven to control the opening degree of the three-way control valve 11 or 12. In this way, feedback control is performed to bring the detected pressure close to the pressure command value.

On the other hand, in the flow rate control, the controller 30 determines the flow rate command value according to the operation signal, and the three-way control valve 1 is determined based on the deviation between the flow rate command value and the identified flow rate.
The opening command value for 1 or 12 is determined, and the pilot valve drive circuit 33 or 34 is based on the deviation between this opening command value and the opening of the three-way control valve 11 or 12 detected by the stroke sensor 23 or 24. Feedback control for controlling the opening of the three-way control valve 11 or 12 via the pilot valve 21 or 22 to bring the identified flow rate close to the flow rate command value is performed.

In the present invention, the pressure of the C port 3 or 4 of the three-way control valve 11 or 12 on the meter-out side is changed to the C-port 4 or the C port 4 of the three-way control valve 12 or 11 on the meter-in side, especially when the hydraulic motor 10 is decelerated. 3 according to the identification flow rate flowing through the controller 3 and the operation amount of the operation device 32.
The pressure control (brake pressure control) is performed based on the deviation from the reference flow rate Qs set at 0.

The control procedure of the present invention will be described below with reference to the flow charts of FIGS. The processing in these flowcharts is performed by the controller 3
The value 0 is repeated every fixed period.

FIG. 3 is a flow chart showing the procedure for determining the turning direction of the hydraulic motor 10 (determination on the meter-in side and the meter-out side). It should be noted that this processing corresponds to the processing by the turning direction determination means 112 in FIG.

In step 1, the first (circuit 1 side)
Flow rate Qid flowing through the C port 3 of the three-way control valve 11
(A) and the identified flow rate Qid (B) flowing through the C port 4 of the second (circuit 2 side) three-way control valve 12 are calculated.

In step 2, the identified flow rates Qid (A) and Qid (B) calculated in step 1 are both substantially 0.
Is determined. Here, the identification flow rate Qid
If (A) and / or Qid (B) are not substantially 0, the actuator is already turning,
The right turn mode or the left turn mode may be maintained as it is.

On the other hand, the identification flow rates Qid (A), Qid
If both (B) are substantially 0, the operation device operation amount St is detected in step 3, and the operation status of the operation device 32 is confirmed.

Here, if the operation amount St of the operating device is St = 0, the routine proceeds to step 4, where the hydraulic motor 10 is set to the stopped mode.

If the operation amount St of the actuator is less than 0, the routine proceeds to step 5, where the hydraulic motor 10 is set to the left turning mode, and at step 6, the first three-way control valve 1
1 serves as a meter-out side valve, and the second three-way control valve 12 serves as a meter-in side valve.

On the other hand, if the actuator operation amount St> 0, the routine proceeds to step 7, the hydraulic motor 10 is set to the right turning mode, and at step 8, the first three-way control valve 1
1 is the meter-in side valve, and the second three-way control valve 12 is the meter-out side valve.

FIG. 4 is a flow chart showing the procedure of pressure control according to the present invention.

In step 11, the input signal input by the handle operation to the operating device 32 is taken into the controller 30 as the operating device operating amount St (FIG. 8).
Corresponding to the operation amount detection means 111).

In step 12, the required amount Rq is calculated by the function Rq = f ₁ (St) stored in advance in the controller 30 based on the operating device operation amount St.
Is required. The function f ₁ that determines the required amount Rq is
Specifically, as shown in FIG. 5, for example, the sign varies depending on the turning mode of the hydraulic motor 10, and the sign of the operation amount St of the operating device is reversed in the left turning mode. That is, in the right turn mode, the required amount Rq increases in proportion to the operation amount St of the actuator being moved in the + direction by the function indicated by the solid line in the figure.
In the left turn mode, the request amount Rq is determined by the function indicated by the broken line in the figure such that the request amount Rq increases in proportion to the operation device operation amount St being moved in the − direction.

In step 13, the required amount Rq
Based on the above, the reference flow rate Qs is obtained by the function Qs = f ₂ (Rq) stored in advance in the controller 30 (corresponding to the reference flow rate calculating means 113 in FIG. 8).
This function f ₂ gives a reference as to how much the flow rate on the meter-in side is given in response to the operation of the operating device, and is determined according to the required deceleration characteristic, for example, as shown in FIG. It is what is done. In the function f _{2 of} FIG. 6, when the required amount Rq is a small value, the change in the reference flow rate Qs with respect to the change in the required amount Rq is made small, and the operation unit 32
Is possible, and when the required amount Rq becomes a large value, the change in the reference flow rate Qs with respect to the change in the required amount Rq is increased so that a sufficient flow rate can be obtained by an appropriate handle operation. It has become.

In step 14, the identified flow rate Qid (M / I) flowing through the C port 3 or 4 of the meter-in side three-way control valve 11 or 12 is calculated (identified flow rate calculation means 110 in FIG. 8).

In step 15, the controller 3
This identification flow rate Qid is determined by the deceleration request determination means within 0.
(M / I) is compared with the reference flow rate Qs. By this comparison, it is determined whether the hydraulic motor 10 is required to decelerate or accelerate (corresponding to the deceleration determination means 114 in FIG. 8). Here, acceleration is requested when the identified flow rate Qid (M / I) is smaller than the reference flow rate Qs, and at this time, the subsequent processing is not performed and the process returns to the upper processing. On the other hand, the deceleration request is issued when the identified flow rate Qid (M / I) is larger than the reference flow rate Qs. At this time, the deceleration operation from step 16 onward is performed.

In step 16, the pressure command value Pcom (M / I) for the C port 3 or 4 of the meter-in side three-way control valve 11 or 12 is set (corresponding to the pressure command value calculating means 115 in FIG. 8). . This pressure command value P
com (M / I) is a value that does not hinder the braking operation during the deceleration operation of the hydraulic motor 10, for example, Pcom.
Set (M / I) = 0 bar. However, the pressure command value Pcom (M / I) is set to a value of 0 bar or more so that the pressure on the meter-in side does not become a negative pressure during the deceleration operation.

In step 17, the pressure command value Pcom (M / O) of the C port 4 or 3 of the meter-out side three-way control valve 12 or 11 is set (corresponding to the pressure command value calculating means 115 in FIG. 8). . This pressure command value Pcom
(M / O) is the brake pressure of the hydraulic motor 10, and is stored in the controller 30 based on the difference (Qid (M / I) −Qs) between the identified flow rate Qid (M / I) and the reference flow rate Qs. Pre-stored function Pcom (M /
O) = f ₃ (Qid (M / I) −Qs). The function f ₃ is, for example, as shown in FIG. 7, a difference (Qid (M / I) between the identified flow rate Qid (M / I) and the reference flow rate Qs.
When I) -Qs) is small, the pressure command value Pcom
(M / O) is also set to a small value to prevent sudden braking operation.

In step 18, the opening instruction of the meter-in side three-way control valve 11 or 12 is performed, and the pressure control on the meter-in side is performed so that the pressure on the meter-in side matches the pressure command value Pcom (M / I) ( (Corresponding to the opening command value calculating means 116 in FIG. 8). The opening command value at this time is determined by the pressure command value Pcom (M / I) and the pressure sensor 2
It is performed by the control calculation means in the controller 30 based on the deviation from the pressure of the C port 3 or 4 of the meter-in side three-way control valve 11 or 12 detected by 5 or 26.

In step 19, the opening command of the three-way control valve 12 or 11 on the meter-out side is issued, and the pressure is controlled so that the pressure on the meter-out side matches the pressure command value Pcom (M / O) ( (Corresponding to the opening command value calculating means 116 in FIG. 8). The opening command value at this time is a deviation between the pressure command value Pcom (M / O) and the pressure of the C port 4 or 3 of the meter-out side three-way control valve 12 or 11 detected by the pressure sensor 26 or 25. It is decided based on.

Next, the operation will be described.

The hydraulic control system according to the present invention includes a hydraulic motor 10.
It is mounted on an industrial machine such as an upper car body of a power shovel driven by or a construction machine, and as the operator operates the operating device 32 of the hydraulic motor 10,
The supply of hydraulic pressure to the hydraulic motor 10 is controlled.

The operation amount St of the operation device 32 is the controller 3
It is taken into 0, and the reference flow rate Q for this manipulated variable St
s is set, but the three-way control valve 11 or 12 on the meter-in side is different depending on whether the hydraulic motor 10 is in the right turning mode or the left turning mode. Therefore, the hydraulic motor 10 is set in the right turning mode. Whether the vehicle is in the left turn mode or not is determined by the controller 30 in addition to the operation direction, and the flow rate on the meter-in side is controlled to the reference flow rate Qs according to the operation amount St of the operation device 32 by the operator. Pressure control is performed on the meter-out side.

In the following description, the hydraulic motor 10 is in the right turn mode, the first three-way control valve 11 on the first circuit 1 side is the meter-in side three-way control valve, and the second circuit 2
It is assumed that the second side three-way control valve 12 is a meter-out side three-way control valve. Therefore, when the hydraulic motor 10 is in the left turn mode, the circuit 1 side and the circuit 2 side are referred to in the following description.
The side (first and second) is completely replaced with the meter-out side and the meter-in side, and the same operation is performed.

By the way, the reference flow rate Qs corresponding to the operation of the operation device 32 thus determined is compared with the meter-in side identified flow rate calculated by the controller 30, and whether the operator makes a deceleration request, It is determined whether an acceleration request is being made. As a result, if a deceleration request is made, the brake pressure on the meter-out side is controlled so that the reference flow rate Qs matches the identified flow rate on the meter-in side.

The pressure command value Pcom (M / O) for the meter-out side brake pressure is determined based on the deviation between the reference flow rate Qs and the meter-in side identified flow rate. Further, from the deviation between the pressure command value Pcom (M / O) and the load pressure on the meter-out side (pressure of the C port 4) detected by the pressure sensor 25, the opening degree for the three-way control valve 12 on the meter-out side. The command value is determined.

The pilot valve drive circuit 34 and the pilot valve 22 feedback-control the opening of the three-way control valve 12 based on the deviation between the opening command value and the opening of the meter-out side three-way control valve 12.

At the time of deceleration, the three-way control valve 11 on the meter-in side has a pressure command value Pcom at a pressure (for example, 0 bar) that does not hinder the deceleration operation of the hydraulic motor 10.
(M / I), and pressure control is performed so that the pressure of the C port 3 is maintained at this pressure command value Pcom (M / I).

As described above, according to the present invention, the hydraulic motor 10
Is controlled by the brake pressure by the three-way control valve 12 on the meter-out side. Since this brake pressure is determined based on the deviation between the reference flow rate Qs on the meter-in side and the identified flow rate, sudden braking or meter-out The side three-way control valve 11 or 12 can be effectively prevented from moving on and off, and smooth deceleration without hunting or the like is possible.

That is, a large brake pressure is generated in the initial stage of deceleration with a large flow rate deviation, the rotational speed of the hydraulic motor 10 decreases, and the brake pressure also decreases as the deviation decreases. Smooth deceleration is performed.

Further, since the function for calculating the required amount Rq, the reference flow rate Qs, and the pressure command value Pcom (M / O) can be arbitrarily set in the controller 30, this deceleration characteristic can be freely changed. Therefore, appropriate deceleration characteristics can be easily obtained according to demand.

Further, even when the hydraulic motor 10 is stopped after this deceleration, according to the present invention, the opening degree of the three-way control valve 12 on the meter-out side can be adjusted by pressure control.

For example, as shown in FIG. 7, the operating device 32
Is set to a neutral state, and the operating device operation amount St, the required amount Rq, the reference flow rate Qs, and the deviation Qid (M / I) −Qs are all zero, that is, even if the rotation of the hydraulic motor 10 is temporarily stopped, By setting the pressure command value Pcom (M / O) to a predetermined small value, high pressure that causes reverse rotation of the hydraulic motor 10 is prevented from occurring on the meter-out side. Therefore, even when the vehicle is stopped after deceleration, the residual pressure on the meter-out side is appropriately released, and the swing-back phenomenon of the hydraulic motor 10 can be effectively prevented.

Therefore, the hydraulic motor 10 can be smoothly decelerated and stopped without the need for a skilled operator, so that the construction machine equipped with the hydraulic control device of the present invention is remarkably improved in operability.

[0058]

According to the first invention, when the deceleration request for the hydraulic actuator is issued, the deceleration of the hydraulic actuator is controlled by the brake pressure by the three-way control valve on the meter-out side. Since it is determined based on the deviation between the reference flow rate on the meter-in side and the identified flow rate, it can be effectively prevented that the brake is suddenly applied or the three-way control valve on the meter-out side makes an on-off movement.
Smooth deceleration without hunting is possible.

According to the second aspect of the present invention, a large brake pressure is set at the initial stage of deceleration, the brake pressure is reduced as the deceleration progresses, and smooth deceleration control is realized. On the other hand, even after the deceleration, the meter continues to be stopped. By controlling the three-way control valve on the OUT side to such an extent that the pressure value on the meter-out side does not cause reverse rotation of the hydraulic actuator, the residual pressure on the meter-out side is appropriately released, and the swing-back phenomenon of the hydraulic actuator is effective. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a three-way control valve of the same.

FIG. 3 is a flowchart showing a procedure for determining a turning direction.

FIG. 4 is a flowchart showing a procedure of pressure control.

FIG. 5 is a characteristic diagram showing a relationship between an operation amount St of the operating device and a required amount Rq.

FIG. 6 is a characteristic diagram similarly showing a relationship between the required amount Rq and the reference flow rate Qs.

[Fig. 7] Similarly, the identified flow rate Qid (M /
It is a characteristic view which shows the relationship between I) and reference | standard flow volume Qs.

FIG. 8 is also a claim correspondence diagram.

[Explanation of symbols]

 1 1st circuit 2 2nd circuit 10 Hydraulic motor 11 First three-way control valve 12 Second three-way control valve 21 Pilot valve 22 Pilot valve 23 Stroke sensor 24 Stroke sensor 25 Pressure sensor 26 Pressure sensor 27 Pressure sensor 30 Controller 32 Manipulator 33 Pilot valve drive circuit 34 Pilot valve drive circuit 100 Tank 101 Pump 102 Hydraulic actuator 103 First three-way control valve 104 Second three-way control valve 105 First load pressure detection means 106 Second load pressure detection means 107 Supply pressure detecting means 108 First opening detecting means 109 Second opening detecting means 110 Identification flow rate calculating means 111 Manipulation amount detecting means 112 Turning direction determining means 113 Reference flow rate calculating means 114 Deceleration determining means 115 Pressure command value calculation Stage 116 opening command value calculating means 117 first valve spool driving means 118 second valve spool driving means

Claims (2)

[Claims] 1. A hydraulic actuator for receiving a hydraulic pressure from a pump to drive a load, and a first three-way device provided on the first circuit side of the hydraulic actuator for switching and connecting the tank side and the pump side to the hydraulic actuator. A control valve, a second three-way control valve provided on the second circuit side of the hydraulic actuator for switching and connecting the tank side and the pump side to the hydraulic actuator, and the hydraulic actuator for the first and second three-way control valves Side and second load pressure detecting means for detecting the side load pressure, supply pressure detecting means for detecting the pump side supply pressure of the first and second three-way control valves, and the first and second First and second opening degree detecting means for detecting the opening degree of the three-way control valve, and an identification flow rate flowing through the meter-in side and the meter-out side of the hydraulic actuator is calculated from these detection signals. Identification flow rate calculation means, operation amount detection means for detecting the operation amount of the operation device, swing direction determination means for determining the swing direction of the hydraulic actuator, and reference flow rate flowing on the meter-in side of the hydraulic actuator based on the operation amount. A reference flow rate calculation means for setting, a deceleration determination means for determining that a deceleration request for the hydraulic actuator is issued from the operating device, and a reference flow rate and an identified flow rate on the meter-in side of the hydraulic actuator during deceleration of the hydraulic actuator. Pressure command value calculation means for setting a pressure command value for the load pressure on the meter-out side of the hydraulic actuator from the deviation and for setting a predetermined pressure command value that does not prevent deceleration of the hydraulic actuator even for the load pressure on the meter-in side, Based on these pressure command values, the opening degree of the first and second three-way control valves is compared. Opening command value calculating means for setting the opening command value, and first and second valve spool driving means for driving the valve spools of the first and second three-way control valves based on the opening command value. A hydraulic control device comprising: 2. The opening of a three-way control valve on the meter-out side when the hydraulic actuator stops after deceleration, so that the pressure value on the meter-out side does not cause reverse rotation of the hydraulic actuator, and the reference on the meter-in side is set. The pressure is controlled so that the flow rate and the identified flow rate on the meter-in side increase as the deviation increases.
The hydraulic control device described in.