JPH0437888B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is directed to stop control of a rotating body that automatically stops the rotating body at a predetermined position when the rotating body having a large inertia force is driven by a hydraulic motor. Regarding equipment.

[Background of the invention]

In a rotating body with a large inertial force, such as a hydraulic excavator, the upper rotating body, which is rotatably mounted on the traveling body, can rotate 360° with respect to the traveling body. Objects (e.g. earth and sand) can be transferred to other locations simply by pivoting the superstructure. Such a revolving body will be explained with reference to the drawings.

FIG. 3 is a top view of the upper revolving body of the hydraulic excavator. Reference numeral 1 indicates an upper revolving structure that is rotatably installed on a running body (not shown) of a hydraulic excavator;
is a front unit swingably attached to the upper revolving body 1. The front 2 is composed of a boom 3, an arm 4, and a bucket 5 that are swingably attached to each other. Reference numeral 6 denotes a hydraulic motor that drives the upper rotating body 1 to rotate relative to the traveling body. When the hydraulic motor 6 is driven in a certain direction, the revolving superstructure 1 rotates together with the front 2 on the traveling structure, for example, in the direction of arrow R, and when the hydraulic motor 6 stops, the revolving superstructure 1 also stops. Therefore,
Objects loaded on the bucket cart 5 can be transferred to a predetermined position, for example, the position indicated by the two-dot chain line in the figure.

FIG. 4 is a drive circuit diagram of the hydraulic motor. In the figure, 6 is the hydraulic motor shown in FIG. 3, 7 is a hydraulic pump that supplies pressure oil to the hydraulic motor 6, and 8 is the hydraulic motor 6 interposed between the hydraulic motor 6 and the hydraulic pump 7.
This is a directional control valve that controls the supply of pressure oil to.
A and B indicate the main circuit of the hydraulic motor 6. 9a, 9
b are relief valves connected between main circuits A and B, respectively.

Now, when the directional control valve 8 is switched to the left position in the figure, pressure oil from the hydraulic pump 7 is supplied to the hydraulic motor 6 via the main circuit A. This drives the hydraulic motor 6, and the oil from the hydraulic motor 6 is returned to the tank via the main circuit B. By driving this hydraulic motor 6, the upper revolving body 1 is rotated, for example, in the direction of the arrow in FIG. In this state, when the directional control valve 8 is returned to the neutral position as shown in the figure to stop the upper revolving structure 1, the pressure oil supply circuit from the hydraulic pump 7 and the return oil circuit from the hydraulic motor 6 to the tank are cut off. Then, the hydraulic motor 6 performs a pumping action due to the inertial force of the upper revolving structure 1, and the main circuit B becomes high pressure, and a braking force (stopping torque) corresponding to the pressure difference between the two main circuits A and B is generated. The rotating body 1 stops.

Incidentally, since the moment of inertia of the upper revolving structure 1 is extremely large, if the directional control valve 8 is set to the neutral position while the hydraulic motor 6 is being driven as described above, an abnormally high pressure will be generated in the main circuit B (the main circuit on the rotation direction side). occurs. For this reason, relief valves 9a and 9b are provided, and when the high pressure generated in the main circuit B exceeds the set pressure of the relief valve 9, the pressure oil in the main circuit B is discharged from the main circuit A.
He is forced to run to the side.

In such a hydraulic circuit, the upper revolving body 1
Even if the directional control valve 8 is switched to the neutral position in an attempt to stop the hydraulic motor 6, the hydraulic motor 6 rotates while the pressure oil is relieved from the relief valve 9a or the relief valve 9b, and the upper rotating body 1 is rotated by the amount of pressure oil relieved. flows and stops. This flow rate (flow angle) is determined by the moment of inertia, the stopping torque, and the speed of the upper revolving structure 1 when the directional control valve 8 is switched, as will be described later.

Conventionally, when an operator rotates the upper revolving structure 1, the operator stops the upper revolving structure 1 at a predetermined position while controlling the flow rate using the directional control valve 8 in consideration of the upper flow rate. By the way, when the object (for example, earth and sand) loaded on the bucket 5 is transferred to a predetermined fixed position and such transfer is performed repeatedly, there is a desire to automate the operation of the upper revolving structure 1. However, as mentioned above, when the revolving upper structure 1 is stopped, a flow rate determined by the moment of inertia, stopping torque, and speed occurs, and since these values are constantly changing, the flow rate is not constant. In automatic operation, there was a problem in that it was extremely difficult to stop the revolving superstructure 1 at a predetermined position. In this way, in order to implement automatic operation of the revolving superstructure 1, it is necessary to either ignore the extremely poor accuracy of its stopping position, or to
Alternatively, the only way to compensate for the deterioration in the accuracy of the stopping position was to extremely reduce the turning speed.

However, such transfer often requires precision in the stopping position, and a reduction in the rotation speed has the problem of significantly deteriorating work efficiency.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a stop control device for a rotating body that can solve the above-mentioned conventional problems and automatically stop a rotating body accurately at a predetermined position. is to provide.

[Summary of the invention]

In order to achieve the above object, the present invention determines the turning speed, moment of inertia, and stopping torque of the rotating body while it is turning, calculates the flow rate of the rotating body from these values, and calculates the flow rate of the rotating body until it reaches a predetermined stopping position. When the interval becomes less than the above flow rate, control is performed to reduce the supply of pressure oil to the hydraulic motor, and after the start of the control, the ratio of the moment of inertia to the stop torque after the start of the control is maintained constant. That is, even if the moment of inertia changes, the amount of tilting of the hydraulic pump is controlled so as to change the stopping torque accordingly, and thereby the flow rate calculated at the start of the control is held constant. It is characterized by the following.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a system diagram of a stop control device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted. 10 is a flushing valve connected between main circuits A and B;
1 is a relief valve connected to the flushing valve 10, 12a and 12b are check valves, 13 is a charge pump that supplies pressure oil to the main circuits A and B via the check valves 12a and 12b, and 14 is a discharge side circuit of the charge pump 13. It is a relief valve connected to. Reference numeral 15 denotes a variable displacement double tilting hydraulic pump (hereinafter referred to as double tilting hydraulic pump), and 15a denotes a displacement displacement variable mechanism (hereinafter represented by a swash plate) of the double tilting hydraulic pump 15. These constitute a hydraulic closed circuit.

Reference numeral 16 indicates a tilting angle control device for controlling the tilting of the swash plate 15a, 17 indicates a pilot hydraulic pump, and 18 indicates a tilting angle control device 16 and a pilot hydraulic pump 17.
This is a control valve interposed between the 19 is the swash plate 15
a tilt angle sensor 20 for detecting a tilt angle of a;
a and 20b are pressure sensors that detect the pressures of the main circuits A and B, respectively; 21 is an angle sensor that detects the position of the upper revolving structure 1; and 22 is a stop position setting device that sets the stop position of the upper revolving structure 1. . 23 is a tilt angle sensor 19, pressure sensors 20a, 20b,
This is an arithmetic processing device that inputs signals from the angle sensor 21 and the stop position setting device 22 and performs necessary calculations and control, and is composed of a microcomputer.

Even in such a closed circuit, when the swash plate 15a of the double tilting hydraulic pump 15 is returned to the neutral position, the main circuit A is activated in the same manner as when the directional control valve 8 is returned to the neutral position in the hydraulic circuit shown in FIG. , B, and the pressure oil on the high pressure side is about to be relieved by either the relief valve 9a or the relief valve 9b, but in this embodiment, the swash plate is appropriately controlled. By doing so, it becomes possible to generate brake pressure without generating relief loss.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. 2 and the top view of the revolving upper structure shown in FIG. 3. In FIG. 3, S indicates a reference line for angles, and all angles in this embodiment are expressed as angles from the reference line S. This reference line may be set anywhere, but for example, the angle sensor 2
It is convenient to use the reference position of 1 (for example, the position of output 0) as the reference line. θ is the angle of the current position of the revolving upper structure 1, and θ ₀ is the angle of the position at which the revolving upper structure 1 is desired to be stopped. The angle θ is obtained from the angle sensor 21, and
The angle θ ₀ is output from the stop position setting device 22 .

When the upper revolving body 1 turns in the direction of arrow R in FIG.
is input from the angle sensor 21, and the angle θ ₀ is input from the stop position setting device 22 (step S ₁ shown in FIG. 2).
Based on these values, calculate the angular velocity θ〓, the angular acceleration θ¨, and the remaining angle from the current position to the stop position (θ−
θ ₀ ) is calculated (step S ₂ ). The method of calculating the angular velocity θ〓 and the angular acceleration θ〓 is well known, so a description thereof will be omitted.
Next, it is determined whether the calculated angular acceleration θ is 0 or not (step S ₃ ). When the angular acceleration θ¨ is not 0, that is, when the rotating upper structure 1 is not rotating at a constant speed,
Signal P _i of pressure sensor 20a and pressure sensor 20
The signal P ₀ of signal b is input (step S ₄ ), and the absolute value P of the difference is calculated (step S ₅ ). Next, the stopping torque T and the moment of inertia I are calculated based on the absolute value of this difference (pressure difference) P and the previously calculated angular acceleration θ. (Step _S4 ).

Here, calculation of the stopping torque T and the moment of inertia I will be explained. Both pressure sensors 20a, 20
Assuming that the pressure difference of b is P as described above, and the capacity of the double tilting hydraulic motor 15 is Q, the stopping torque T can be calculated by the following equation.

T=P・Q/2π (1) Moreover, the moment of inertia I can be calculated by the following formula.

I=T/θ (2) In reality, these values are determined by taking motor efficiency etc. into consideration, but the details will be omitted. In this way, in step _S6 , the stopping torque T and the moment of inertia I are determined. Then, the ratio between the moment of inertia I and the stopping torque T at this time is determined and stored as W (step S ₇ ). This ratio is used in the control after the upper rotating body 1 starts its stopping operation, as will be described later. Then the established brake flag is
It is checked whether or not it is OFF (step S ₈ ), and if the brake flag is OFF, that is, when the stopping motion of the revolving superstructure 1 has not started, the flow rate θ ₂ is calculated (step S 8 ). _S9 ).

The flow rate θ ₂ can be calculated by the following equation based on the angular velocity at that point found in step S ₂ , the moment of inertia I and the stopping torque T at that point found in step S ₆ .

θ ₂ = 1/2・I/T・(θ〓) ² ………(3) In other words, if you try to stop the upper revolving structure 1 at that point, how long will it take for the upper revolving structure 1 to stop? The angle of flow will be calculated.

The flow rate θ ₂ calculated in this way is the remaining angle (θ − θ ₀ ) to the stop position calculated in step S ₂ .
(step S ₁₀ ), and if the angle (θ - θ ₀ ) is larger than the flow angle θ ₂ , the procedure determines whether the angular velocity at that time is 0 (whether the upper rotating body 1 is in a stopped state or not). After making the determination in _S11 , return to step _S1 again. on the other hand,
If it is determined in step S ₃ that the upper revolving structure 1 is rotating at a constant speed (θ¨=0), steps S ₄ to _{S 9} necessary for stop control operation are not performed, and the procedure is immediately executed.
Move on to processing _S10 . For the flow rate θ ₂ in step S ₁₀ in this case, the value determined in step S ₉ immediately before the upper rotating body 1 reaches a constant speed is used.

In step _S10 , when it is determined that the remaining angle (θ - θ ₀ ) has become less than the flow rate θ ₂ , the specified brake flag is turned on and the double tilting hydraulic pump 1 is turned on.
Return the swash plate 15a of No. 5 to the neutral direction (step _S12 ), and calculate the moment of inertia I and stopping torque T calculated in step _S7 .
The ratio W is stored as the value W ₀ at the time the brake flag changes to ON (step S ₁₃ ). As described above, the flow rate θ ₂ is the angle at which the upper rotating body 1 flows after the stop operation until the upper revolving structure 1 stops. This flow rate θ ₂
assumes that the above ratio W is constant. Therefore, after the stopping operation, the ratio W must always be maintained at the ratio W ₀ at the time of starting the stopping operation. The ratio W ₀ is used in the processing described later in this sense.

In step _S14 , the pressure difference P obtained in step _S5 when the brake flag changes to ON is stored as the target brake pressure P _B. Then, the arithmetic processing unit 23 sends the swash plate 1 to the control valve 18 so that the brake pressure in the circuit becomes the target brake pressure P _B.
A tilting command to tilt 5a is output. (procedure
_S15 ). After outputting this command, the process returns to step _S1 via step _S11 , and steps _S1 to _S8 are executed again. In this case, the brake flag has already been set in step S ₁₂ .
Since it is ON, the process starts from step _S8 .
Move to _S16 .

In step _S16 , the previously stored value _W0 is taken out and compared with the currently calculated value W. That is, since the moment of inertia I changes after the start of the stopping operation, a comparison is made to see how much the ratio with the stopping torque T has changed. Then, in step _S17 , a stopping torque for making the value W equal to the value _W0 is calculated, and a target brake pressure P _B for producing this stopping torque is calculated. Step S ₁₅
Then, a tilt command is output to tilt the swash plate 15a so that this target brake pressure P _B is obtained. By controlling the tilting of the swash plate 15a, the value of the stopping torque T changes in accordance with the change in the moment of inertia I, and the value I/T is always kept equal to the value _W0 . In this way, when the upper rotating body 1 stops at the set stop position (angle θ ₀ ), the procedure
In _S11 , it is determined that the process should be stopped, and the process ends.

In this way, in this embodiment, the flow rate is calculated based on the moment of inertia, stopping torque, and speed of the upper rotating body, and when the distance to the set stop position becomes less than the flow rate, the double tilting hydraulic pump The swash plate was returned to the neutral direction, and the tilting of the swash plate was then controlled to maintain a constant ratio of moment of inertia to stopping torque, making it possible to accurately stop the upper revolving structure at a predetermined position. can.

Note that the moment of inertia is not necessarily calculated using the calculation method using equation (2), but may be calculated using the method described below. That is, an angle meter is attached to each swinging part of the front, and the position of the center of gravity of each link is calculated. Also, the weight of the load inside the bucket is detected by the pressure difference in the boom cylinder, etc. In this way, when the gravity m _i of each unit and the distance l _i from the center of rotation to the center of gravity are obtained, the moment of inertia I can be obtained from the following equation.

I=Σm _i・l _i ² /g (4) However, in the above equation, g is the gravitational acceleration.

Furthermore, in the description of the above embodiments, the upper revolving structure of a hydraulic excavator was exemplified as the revolving structure, but the present invention is not limited to this, and it goes without saying that other revolving structures may be used.

〔Effect of the invention〕

As described above, in the present invention, the flow rate is determined based on the moment of inertia, stopping torque, and speed of the rotating body, and when the distance to the set stop position becomes less than the flow rate, the pressure oil is supplied to the hydraulic motor. The supply of water was reduced by controlling the tilting, and the swash plate valve of the double tilting hydraulic pump was then controlled to maintain a constant ratio of moment of inertia to stopping torque. It can be stopped automatically.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a stop control device for a rotating body according to an embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of the device shown in FIG. 1, and FIG. The top view and FIG. 4 are drive circuit diagrams of the hydraulic motor that drives the upper revolving body of the hydraulic excavator. DESCRIPTION OF SYMBOLS 1...Upper rotating body, 2...Front, 15...Variable capacity double tilting hydraulic pump, 15a...Swash plate, 16...Tilt angle control device, 18...Control valve, 20a, 20b...
Pressure sensor, 21... Angle sensor, 22... Stop position setting device, 23... Arithmetic processing device.

Claims (1)

[Claims] 1 In a system equipped with a rotating body having a large inertial force, a hydraulic motor that drives the rotating body, and a hydraulic pump that supplies pressure oil to the hydraulic motor,
a speed detecting means for detecting a turning speed of the rotating body; a stop position setting means for setting a position at which the rotating body should be stopped; a calculating means for calculating a stopping torque and a moment of inertia of the rotating body; stop means for stopping the supply of pressure oil from the hydraulic pump to the hydraulic motor based on the detected value of the means, the value set by the stop position setting means, and the calculated value of the production means; 1. A stop control device for a revolving superstructure, comprising: tilting control means for controlling tilting of the hydraulic pump so that the ratio of the stopping torque to the moment of inertia is constant.